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bal-tec - ball material selection

You need some balls just like the sample, but how do you find out what it is? Or you may need help in choosing the right ball material for a particular application. The safest place to start is with the application itself. What does the ball do?

"Bearing balls" is the general term for any hard steel ball that will function in a roller bearing application. Common materials are hard chrome steel 52100, C/S, 440C hard stainless steel and carbonized high carbon steel. High speed steel might be added to this list for severe and high temperature applications.

If it is a ball bearing application, the most likely material is chrome steel which is 52100 chrome alloy steel. This is a relatively inexpensive material. This material is very hard, at about 62 HRC (Hardness on the Rockwell "C" scale). It is highly magnetic. It is not corrosion resistant, it will rust easily. Chrome alloy steel balls comprise about 90% of all balls manufactured. This material is a high carbon (1.00%), chrome (1.36%) alloy steel that will harden into the 60 - 65 HRC range when oil quenched from a soaking temperature of 1475 F. The hardness usually ends up at 62 HRC. The stress relieving or drawing temperature is 325 F. This does not mean that this steel can be used up to this temperature. We have run repeated tests where we elevated the temperature to 325 F. In the first three cycles, the samples dropped one point of HRC each time they were treated. It begins to lose its hardness at temperatures above 300 F. It is a fine grade material that can be precision ground and lapped spherical within a few millionths of an inch with a sub micro inch surface quality. It is highly magnetic in the sense that it will be attracted by a magnet.

51100 steel is a very low alloy chrome steel that was widely used during WW II as a means of conserving chromium. It is more susceptible to stress cracking during the quenching cycle of heat treating than the more conventional 52100 chrome alloy steel. This material is highly magnetic. It will through harden in reasonable sections. It will harden to 60 to 65 HRC. With a 325 F draw, it will average 62 HRC.

The third possibility is that, it is a case hardened carbon steel, i.e. hard carbon steel. For the most part, these less expensive balls are used in cheap bearings for casters, conveyors, bicycles and toys.

This material is highly magnetic. It has a thin carbon rich layer, cooked into the surface, that is then hardened to the equivalent of 60 HRC. This material is extremely rust prone. These balls are manufactured from low carbon steel wire, i.e. type 1018 steel. The ball blanks are cold headed, flashed and ground. They are then heated to 1700 F in a very carbon-rich, gaseous environment to develop a high carbon case or shell in a rotary hearth furnace--carbon is literally cooked into the outer surface of the steel balls. After cooling, they are re-heated and oil or water quenched, depending on size. Next, they are tempered at 325 F to relieve the stresses and to reduce the hardness slightly so they won't be brittle. After carbonizing, this material may be heat treated to the equivalent of 60 HRC. Because of the thin hardened layer, a special micro hardness test must be used to evaluate the hardness. It should be remembered that the hard outer surface is only a thin case or shell. Finally, these balls are ground and polished.

Soft low carbon steel (type 1018; 0.18% Carbon, 0.8% Manganese, balance Fe - Iron) balls are produced commercially in most common fractional inch sizes, up to 1 inch ( 25.4 mm). These balls are ground round with a highly polished decorative finish.

We custom produce soft, low carbon steel balls in the entire size range from subminiature to 17 inches (432 mm). These custom made balls can be supplied as: precision machined only, precision ground, or precision ground and polished. This material can be easily drilled, threaded, and otherwise machined with conventional chip-making machines. Type 1018, soft, low carbon steel, balls are very weldable.

The last common bearing material is high-speed extremely high temperature alloy steel. This is only found in hot bearing applications. High speed steel balls are usually produced from type M50 or M10 steel. Many of the "T" type high speed steels are almost impossible to purchase today, High speed steel's main property is its very high temperature resistance. High speed steel will remain hard even at red temperatures. High speed steels are generally harder than the standard chrome steel. It is typically 65 HRC. This material is highly magnetic. We can usually grind this material with expensive cubic boron nitride abrasive. It can be drilled, threaded and otherwise machined using the EDM process (Electro Discharge Machine).

Precision balls can be produced from this material, but there is really no good reason to use it. The properties of this material have no advantage over the standard 52100 chrome alloy steel, which is less expensive and more readily available.

06 Tool Steel finds frequent use for the production of large and very precision balls. It is reasonably machinable. It is readily available in large diameter, cylindrical form. It will through harden, even in very large diameters. It can be ground and lapped to a very high quality.

Ball screws are very similar to ball bearings in that they generally use either chrome steel or type 440C hard stainless steel. A peculiarity of ball screws is that they typically have a load ball and the next ball is a .001-inch undersized spacer ball, and so on. One half of the balls are load balls and one half are spacer balls.

In exotic aerospace or life threatening situations, you should obviously not use home-grown tests to validate materials since sophisticated alloys like high-speed steel, Stellite or HASTELLOY may test similar to other common materials, but in fact have extremely different physical properties. The Stellite alloys most most frequently used for balls are Star J or number three. They are very hard and wear resistant. See our page, Radiations Hardened Kinematic Systems for more information on Stellite.

Another place where balls are widely used is in the plumbing of pneumatic and hydraulic systems. Ball check valves, flow control valves, pressure relief valves and pressure regulating valves all use ball and seat combinations to perform their functions.

In pure hydraulic oil systems, the most common ball material is chrome alloy 52100 steel. This ball will be very hard, and highly magnetic, but it is not corrosion resistant and will test positive in any of the corrosion tests. In the grinding spark test it will be orange in color with many side bursts, as the carbon burns with the oxygen in the atmosphere (incineration).

Some high-end hydraulic systems may use type 440C stainless steel. This material is highly magnetic, it is hard and it will not react to any of the corrosion tests. In the grinding spark test, it will have a short red spark with almost no side burst. In the plumbing for the food processing industry, HASTELLOY, Stellite and even Tungsten Carbide (TC) balls are often used.

is very hard. It is almost non magnetic. It is extremely corrosive resistant. When spark tested, it will give off almost no indication at all, outside of a few red tracers. HASTELLOY is tough but not very hard. A file will cut it with ease. It is an extremely corrosion-resistant material. The cylindrical bar stock to make these balls costs us $71.00 per pound in 2008. High quality balls of any size can be produced from this material.

Tungsten-carbide is very very heavy. Many times all you have to do is to heft it to distinguish its enormous mass. It will not react to any of the corrosion tests. It will emit no spark at all when ground with a conventional abrasive wheel. It is the hardest of all synthetic materials. If you look at this material critically, it is not a silvery metallic but is a dark gray in color. Tungsten-carbide is only slightly magnetic and is usually easy to distinguish from steel. See our shopping cart for available stock.

In tap water systems, brass balls are often used, although type 316 stainless steel will show up in high-end systems. The bright golden color of the brass gives it away. It is dead soft. It is entirely non-magnetic. The corrosion tests will only brighten the gold color.

Is the ball hard? Measuring the actual hardness of a precision ball is a complicated and difficult procedure. To make a shop test of hardness, first procure a brand-new, flat, fine toothed, mill bastard file. Hold the ball to be tested in the jaws of a set of clamping pliers like vise grips.

A good fast test of corrosion resistance is to immerse pre-cleaned test balls in a 5 percent solution of nitric-acid in alcohol. This "Nital" solution will turn all steels a light to dark gray in just 2 minutes. It won't change the color of corrosive-resistant materials.

An even better test is the copper-sulfate test. This solution consists of copper-sulfate crystals dissolved in a 6-percent solution of sulfuric-acid and water. A drop of this solution on the surface of a clean steel ball will immediately form a bright spot of copper-plating. This solution will not affect any of the corrosive resistant materials within a two-minute period, but may react to hard ferritic or Martensitic stainless-steel after a long period of exposure. See our picture gallery page.

Is the ball magnetic? Here we must be a little careful. Many materials that most people consider totally non-magnetic, like 300 series stainless steels, can become slightly magnetic when it is cold work-hardened. Remember that commercial balls are made by cold-heading the blanks from wire. Then they are rolled between two hard steel plates to remove the cold heading flash from them. Both of these processes generate strains in the balls that will make them at least slightly magnetic.

Use an ordinary pocket magnet to test for magnetism, not one of the very powerful rare earth magnets. If the magnet strongly attracts the ball, it is one of the steel materials. If it doesn't attract it at all, or if it only has a very slight attraction it is one of the corrosive resistant materials, or else a totally nonferrous (without iron) material.

It may sound obvious, but look at the sample ball. For many applications on board ships, it is not unusual to find brass, bronze, or aluminum-bronze balls. It is also common to find these materials in plumbing and valve applications. Clean the ball with a strong detergent; brassy materials will be a golden yellow color. Brass and bronze are totally non-magnetic while aluminum-bronze will be very slightly attracted by a magnet.

is a fairly common plastic ball material. It is heavier than most plastics and quickly sinks in water. It is very white in color. It will actually feel slippery to the touch. This material is the most corrosion-resistant plastic material. This material will operate at the highest and the lowest temperatures of any plastic ball material. This is one of the most expensive plastic materials. See our PTFE ball stock in our shopping cart.

The spark test can be a very effective test procedure to help identify a material. Use an ordinary shop grinder for this test. Ideally use a course (40) grit grinding wheel. This test is more effective in an almost dark area. The grinding wheel should be dressed to remove any metal embedded in the surface. Hold the ball in the same vise grip pliers used for the file hardness test. Hold the ball lightly against the rotating grinding wheel and observe the sparks that result. Lets break the appearance of the sparks coming off the grinding wheel down into three categories: The color of the spark. Don't look at anything but the color. 440c and high-speed steel will give a very red spark. Chrome steel will give a bright orange spark. Hard carbon steel will give a nearly white spark. 300 series stainless, Monel K-Monel and HASTELLOY will give almost no spark at all. If you use a heavy pressure you may get a few tiny red darts. The length of the spark is the next characteristic to look at; 440c and high-speed steel will throw a short spark. Chrome steel will throw a medium long spark. Hard carbon steel will throw a much longer spark on the same wheel at the same pressure. The nature of the spark will vary with the different materials. The free carbon in the steel incinerates or burns in the oxygen of our atmosphere. This forms a burst or side spark that comes off the main spark at an angle. In high alloy steels the carbon is tied up in high temperature combinations of chrome, cobalt, molybdenum or tungsten, so there is very little burst, if any. This group includes type 440C stainless steel and the high-speed steels. In materials such as chrome steel, which only a small percent of alloy, the incineration or explosion of the spark is much more pronounced and occurs closer to the grinding wheel. There will be a lot of side sparks. High carbon steel basically has no alloy except extremely high carbon content, so there are lots of sparks up and down the streamers leaving the wheel. There will be almost no spark with many materials like 300 series stainless, HASTELLOY, Monels or Stellites. Synopsis The best possible aid to spark testing is to have balls of known materials to compare the sparks with. Break the spark into the three characteristics of color, length, and incineration (side sparks or bursts). Add the information regarding the hardness, magnetism and corrosion resistance and you will be able to nail down ninety five percent of the ball materials. Please give our office a call at (323) 582-7348 with any questions, or toll-free at 800-322-5832. Quality To the quest of determining the material, we must add that of determining the required quality. For bearings and ball screws with balls from 1/16" (.0625 inch, 1.59 mm) to 5/8" (.625 inch, 15.9 mm), A.F.B.M.A. grade-25 is a good commercial quality that is good enough for most commercial applications. Request a ball grade chart, printed on plastic, from our office to better understand the quality and grade specifications and one will be sent to you free of charge. It is available as a download from our web site. For larger and smaller balls, a lower quality grade may be used for economic reasons. Grade 50 or grade 100 are usually available as an economic alternative to grade 25. In valve and plumbing applications, much softer corrosive-resistant materials are often used. It is very expensive to produce the highest quality balls in these soft stainless steel and non-ferrous materials. The high quality balls in these materials are usually Grade 100 and good commercial quality balls are Grade 200. Call our office for technical assistance. Ball Materials 1018 Soft Mild Steel Type 1018 soft mild steel has a very low carbon content. This steel is not hard. It can be machined, drilled and tapped. This material is highly magnetic. It will be strongly attracted by a magnet. This is one of the most weldable steel alloys. Hardness is rated at 28 HRC. 17-4 PH 17-4 PH is one of the family of precipitation hardened nickel based alloys. It combines high strength and good corrosion resistance with moderate hardness. It is hardened by soaking at an elevated temperature for a period of time. The most common soaking temperature is 900 F. This heat treating is referred to as H-900. In the solution annealed condition, this material has moderately good machining properties. 15-5 PH is another of the common PH alloys. 300 Series Stainless Steel If the application isn't too severe, type 316 stainless steel may be used. The 300 series stainless steels are basically an alloy of 18% chromium and 8% nickel with the balance ferrite (iron). This material is dead soft at about 30 HRC (Hardness Rockwell "C" scale), and is almost non magnetic in the annealed condition. Pneumatic In pneumatic systems, there is usually water or water vapor present. To prevent rust, type 316 stainless steel is used. The spark test will yield only tiny red tracers. This material will not respond to any of the corrosion tests. It is almost non-magnetic. It is dead soft and the file test will put an immediate flat on the ball. 420 Stainless Steel Type 420 hard stainless steel is the material widely used in Europe. It is very similar to type 440C, which is more widely used in the United States. Type 420 is not quite as hard as the type 440C. One of the advantages of 420 over type 440C is that it has a higher magnetic permeability, so that it is attracted more strongly by a magnetic field. 440C Stainless Steel 440C Stainless Steel is one of the most amazing standard ball materials. It is a very high chromium, high carbon, martensitic stainless steel. Martensite is the very hard state of a high carbon steel. When heat treated from the spherodize annealed condition, it forms an extremely fine grain structure. For hardening, it must be raised to 1900 F. It will harden to 58 - 63 HRC. It is usually at the low end of this range, when tempered at 400 F If the bearing is used in a corrosive or wet environment, it may be a type 440C hard martensitic stainless steel. This material is very magnetic and it is hard, but it is not as hard as chrome steel. It is about 58 HRC (Hardness Rockwell "C" scale). This material is only mildly corrosive resistant and will only respond to corrosion tests with slight pitting. It will eventually corrode in tap water and will not stand up to sea water at all. It is widely used as a premium bearing material and it is the top material for use in gaging products. See our article, Stainless Steel Balls, Type 440C Hardened for more information. Aluminum Balls 1100 series aluminum is commercially pure aluminum. It is a very light weight material that is a silvery white color, one of the natural base elements, and very ductile. Balls made of 1100 series aluminum are often used as closures. They are squashed or upset to permanently close a hole (an inside diameter). It is difficult to locate this material in less than mill-run quantities. 2017 aluminum is a copper alloy of aluminum that was originally developed for the manufacture of rivets. Its number one quality is that it can be safely cold-headed, which makes it an excellent choice as a material for precision balls. This is the aluminum alloy specified by Mil-B-1083, the generally accepted military specification for precision balls. This alloy has also been chosen by the AFBMA (Anti Friction Bearing Manufacturers Association as a standard ball material. This material is usually heat treated to the "T4" condition. This is not a good choice if the ball is to be anodized. High quality balls can be produced from this alloy. Aluminum Alloy 2017 Manganese 0.7% Copper 4.0% Magnesium 0.5% Aluminum balance 2024 aluminum alloy is an aluminum copper alloy. It is a high strength material, widely used in aircraft. It can be cold headed. The tensile strength of this alloy can be improved by heat treating. This alloy is not a good choice for hard anodizing as the segregation of copper will form voids and can even cause incineration of the metal during the anodizing process. Aluminum balls of all type are often used as closures by compressing them to seal a close fitting hole. Aluminum Alloy 6061 6061 Aluminum alloy is a widely used, readily available, aluminum material. This material should never be cold headed--it can develop internal fissures that will lead to catastrophic failure. This alloy has much better machining qualities than 2017 alloy. This alloy is an excellent choice when the balls are to be hard anodized. The tensile strength of this alloy can be improved by heat treating. This aluminum alloy is relatively light at 0.098 lbs/ cu in. Aluminum Bronze It is very slightly magnetic. An aluminum bronze ball will roll towards a powerful magnet. This material is very resistant to sea water. Some alloys of this material can be heat treated to increase its hardness and tensile strength, but the hardening process reduces corrosive resistance. It is a very good electrical conductor. A286 Balls A286 is one of the exotic Space Age materials. It has good wear properties. It is corrosion resistant. This material must be heat treated to develop its best physical properties. This material is very expensive. Very high quality balls can be produced from this material. Black Oxide Balls Black Phosphate Balls High quality steel balls of both chrome steel and hard stainless steel can be treated chemically to color the surface black. This black iron phosphate actually penetrates the surface so that the original size and surface quality is not affected. The most common application for this surface treatment is to provide identity for these balls. In some bearing and ball screw applications, two different size balls are used in the same device. The larger diameter balls are load bearing balls, and the smaller diameter black balls are used as spacer balls. Brass Balls We manufacture and stock a large variety of brass balls. Brass balls are gold or bright yellow in color. The Standard alloy is 70-30, which is 70% copper and 30% zinc. The only major problem with the metallurgy of brass is segregation. This is due to the high melting point of copper (3000 F) and the low melting point of zinc (800 F). This material is quite ductile and very malleable. It is corrosive resistant to tap water, but does not stand up well in sea water. It is nonmagnetic, an excellent electrical conductor, and has excellent solder ability with soft solder, but may require chemical cleaning to remove an oxide layer. Brass has a hardness of less than 30 HRC, is very machinable, and it may be drilled and tapped easily. Brass is a relatively heavy material at .275 - .316 lbs/cu in (7.60 - 8.75 g / cc). Naval Brass or Naval Bronze Naval Brass or Naval Bronze is very similar to brass, but has an addition of 0.5% to 1.0% tin. This small addition gives to material good corrosive resistance to sea water.Naval brass or bronze is a relatively heavy material at .305 lbs/ cu in. We will custom manufacture special alloys if the material is commercially available. Brass balls are precision ground and polished. They can be produced to AFBMA standards when required. We produce brass balls in all sizes from the sub-miniature to very large diameters. Copper We manufacture copper balls in the entire range of sizes from sub-miniature to several inches in diameter. Pure copper, as well as the many copper alloys, can be used to produce highly accurate precision balls. Copper, usually oxygen free, has excellent electrical and heat conductivity, as well as good corrosion resistance in many harsh environments. It is nonmagnetic. It is sometimes annealed after all forming and machining is completed, to enhance its electrical properties. It is extremely malleable and ductile. It is very soft, but it is gummy and very difficult to machine, tending to gall easily. It is very solderable, and it is very corrosive resistant to sea water. Copper has a distinctly red color. Diamond-Impregnated Brass Balls Diamond-impregnated balls are used to lap the spherical radius in ball valves. They usually have a stem or handle attached to facilitate holding during the lapping process. See our Diamond Impregnated Ball Lap page for more information. Gold An obvious use for gold is for jewelry. The nobility of gold meaning its resistance to corrosion and its good electrical conductivity leads to use in electrical applications. Gold has a high level of x-ray opacity and good bio-compatibility, which leads to its use as x-ray markers in medical applications. As gold is such an expensive material, we do not maintain a stock of gold balls. Hevimet Hevimet is usually sintered from powdered tungsten and powdered copper. Its very heavy weight makes it an alternative to lead in some uses. It is machinable, and unlike lead it is biologically safe. Ball's made of this material are used as counter-weights, and to add mass to mechanical structures. High Speed Steel High speed steel such as M50 and M10 or T15 are usually reserved for hot end bearings and high temperature ball screw applications. These materials are not corrosive resistant and will react to any of the corrosive tests. These materials are very hard. They will test up to 65 HRC. They will be strongly attracted by a magnet. When spark tested, they will give short red tracers with almost no side bursts. These balls are often supplied in very high quality grades, up to A.F.B.M.A. Grade 10. Inconel X Balls 7-18 Inconel is of one the exotic space-age metals, a trademark of Special Metals Corp. Inconel 7-18 is truly an aerospace metal. Inconel is hard and strong. It will continue to perform at high temperatures. It will also perform at temperatures so cold that hydrogen is a liquid. These low temperatures are so cold that there is a special word for it, cryogenic. The highest quality is required for these aerospace oriented balls. In many cases, every single individual ball must have its own pedigree accompanying it. This will include the physical and chemical analysis of the individual bar of material, an ultrasonic examination, and the heat treating process that was performed on it. Along with this will be the diameter of the ball on three orthogonal axii and three polar charts of the roundness taken on three orthogonal axii. A rocket engine using inconel balls depends on the integrity of each individual ball, making them crucial parts of the rocket engine. In addition, Inconel is highly corrosive resistant. It is precipitation hardened. This metal alloy must be heat-treated to develop its good physical properties. Care should be exercised in specifying the desired heat treatment as the furnace time for some processes may be very long and therefore, very expensive. We manufactured Inconel balls for the Apollo and Space Shuttle programs. Inconel is a very expensive material, and may require considerable lead time just to procure the raw material. To see our stock of Inconel balls, click here. Monel There are a number of different Monel alloys, a trademark of Special Metals Corp.. The basic alloy has a minimum of 23% copper and minimum of 60% nickel with small amounts of iron and manganese. This material is very tough but not very hard. It is not heat treatable. Monel is used in very corrosive environments. It is excellent in salt water applications such as valves for sea water. It is also used in the food processing industry. We make Monel balls in a wide range of sizes. Due to its relatively soft nature, AFBMA grade 200 is the normal quality specification, although grade 100 can be achieved with some difficulty. It is relatively soft at about 38 HRC, and it is difficult to drill and tap. MP35N MP35N finds use for check valve applications where no other metal could ever survive. In down hole control valves where the chemistry of the environment would eat a stainless steel ball, balls made of this material will last indefinitely. This material is so tough that producing precision balls from it is a major problem. It cannot be cold headed at all. The forging temperatures are extreme. Like many of the exotic metals, MP35N can be lapped to a very high level of quality, once the spherical blank has been produced. The word expensive was coined to describe this material. Delivery is also a problem as the material has to be special ordered. MP35N Composition Ni, Nickel 35% Co, Cobalt 35% Cr, Chrome 20% Mo, Molybdenum 10% Niobium Niobium, a high density material, is very malleable and ductile. It is widely used in body jewelry. Platinum Platinum balls are widely used in high reliability electrical contacts. For this application, the platinum is alloyed with a small percentage of other elements. In the United States, it is usually alloyed with iridium; and in Europe, it is alloyed with nickel. These toughening and hardening metals have only a slight effect on the properties of the platinum. Platinum is the most noble of metals and is impervious to attack by most acids and bases. Platinum has one of the highest melting points of any metal (1768.3 C, 3214.9 F). As platinum is an expensive material, we do not maintain any platinum items in stock . Phenol Balls Bakelite Balls Phenol Formaldehyde Balls Unlike most other plastic balls, this material is a thermosetting plastic. This means that once this material has been heat cured in the mold, it will not melt again. You can raise the temperature of this plastic until it incinerates, but it will not melt. This material is much harder than any other commercially available plastic ball. It must be compression molded or catalyzed in a mold at high temperature, which makes it much more expensive than thermo plastics that can be injection molded. Ren 41 Ren 41 is an extremely tough high temperature nickel-chrome-molybdenum alloy. The machinability of this material is the very lowest of any commercially available alloy. But once the blank is machined, grinding and lapping are no problem. High quality balls can be produced from this material. Tantalum Balls / Tantalum Beads Tantalum balls or beads find frequent use as radiographic markers, because of their bio-compatibility. These balls can be implanted to form three dimensional markers for orthopedic evaluation after surgery. A ring of these radio graphically opaque markers are used at both ends of stints and shunts, providing a well defined address for the implanted devices. This material is used as an x-ray-opaque tracer in medical implants. An attached ball will define the position of a catheter. Tantalum is a very dense heavy metal (Ta) atomic weight is 180.947, density: 16.6g/cm^3. Unlike tungsten, it is very ductile and malleable. It will produce no reaction with either hydrochloric acid ( HCL) or nitric acid (HNO3). When Tantalum is implanted in a patient, it must be processed according to specification ASTM F560 (Medical Grade). See our sister site, www.tantalumbeads.com, for more information. See our shopping cart for available stock. Titanium Titanium Balls are made in two popular titanium materials. The first is basically pure titanium. This material, grade 2, is widely used in medical applications, where it is frequently used in body implants because it is very bio-compatible. The second, and by far the most frequently used alloy is 6AL4V (6 % Aluminum, 4% Vanadium) titanium. This alloy is available in a variety of wire and bar forms for easy processing into precision balls. Satin finished titanium balls are used as calibration devices for optical inspection devices. Titanium has an unusual hexagonal close-pack atomic structure, as contrasted with a face-centered or a body-centered cubic of most metallic elements. Tungsten Balls Tungsten has one of the highest melting points of any available metal. This is one of the heaviest metals. It is hard, tough, and non-magnetic. This metal is expensive and it is very difficult to machine, grind, or lap. Very high-quality balls can be produced from this material. Waspaloy Balls Waspaloy is one of the older exotic alloys used in high temperature applications. This material is very expensive and is only available in a limited number of shapes. Aluminum Oxide (Ceramic Ball) Aluminum Oxide is an almost white ceramic. Chemically it is Al2O3, also known as alumina balls or aloxite balls . This material is extremely hard. It has excellent electrical insulation properties. It is one of the least expensive and most widely used ceramic ball materials. It is very wear resistant, and it is very stiff with a young's modulus (YM) of elasticity of approximately 45,000,000 pounds per square inch. It can only be used in bearings at low speeds and very light loads. Star J and #3 are the alloys most frequently used for balls. They are very hard and wear-resistant. Silicon Nitride (Ceramic Ball) Silicon Nitride (Si3N4) ceramic has become the standard ceramic ball material for hybrid Ball Bearings. This material is very hard, over 2000 Knoop, and very wear resistant. The weight of silicon nitride balls is only 40% of steel at 3.2 grams per cm (cubic centimeter) . This material is hot isostatic pressed from 1 to 3 micro powder, has excellent fracture toughness even at elevated temperature, and ball quality as good as AFBMA grade-5 can be achieved on this material. Silicon nitride has excellent dielectric properties and extremely high resistivity (insulating properties). More Information For more information on engineering materials, see the site matweb.com .

The best possible aid to spark testing is to have balls of known materials to compare the sparks with. Break the spark into the three characteristics of color, length, and incineration (side sparks or bursts). Add the information regarding the hardness, magnetism and corrosion resistance and you will be able to nail down ninety five percent of the ball materials.

For bearings and ball screws with balls from 1/16" (.0625 inch, 1.59 mm) to 5/8" (.625 inch, 15.9 mm), A.F.B.M.A. grade-25 is a good commercial quality that is good enough for most commercial applications.

Request a ball grade chart, printed on plastic, from our office to better understand the quality and grade specifications and one will be sent to you free of charge. It is available as a download from our web site.

In valve and plumbing applications, much softer corrosive-resistant materials are often used. It is very expensive to produce the highest quality balls in these soft stainless steel and non-ferrous materials. The high quality balls in these materials are usually Grade 100 and good commercial quality balls are Grade 200. Call our office for technical assistance.

Type 1018 soft mild steel has a very low carbon content. This steel is not hard. It can be machined, drilled and tapped. This material is highly magnetic. It will be strongly attracted by a magnet. This is one of the most weldable steel alloys. Hardness is rated at 28 HRC.

17-4 PH is one of the family of precipitation hardened nickel based alloys. It combines high strength and good corrosion resistance with moderate hardness. It is hardened by soaking at an elevated temperature for a period of time.

The most common soaking temperature is 900 F. This heat treating is referred to as H-900. In the solution annealed condition, this material has moderately good machining properties. 15-5 PH is another of the common PH alloys.

If the application isn't too severe, type 316 stainless steel may be used. The 300 series stainless steels are basically an alloy of 18% chromium and 8% nickel with the balance ferrite (iron). This material is dead soft at about 30 HRC (Hardness Rockwell "C" scale), and is almost non magnetic in the annealed condition.

In pneumatic systems, there is usually water or water vapor present. To prevent rust, type 316 stainless steel is used. The spark test will yield only tiny red tracers. This material will not respond to any of the corrosion tests. It is almost non-magnetic. It is dead soft and the file test will put an immediate flat on the ball.

Type 420 hard stainless steel is the material widely used in Europe. It is very similar to type 440C, which is more widely used in the United States. Type 420 is not quite as hard as the type 440C. One of the advantages of 420 over type 440C is that it has a higher magnetic permeability, so that it is attracted more strongly by a magnetic field.

440C Stainless Steel is one of the most amazing standard ball materials. It is a very high chromium, high carbon, martensitic stainless steel. Martensite is the very hard state of a high carbon steel. When heat treated from the spherodize annealed condition, it forms an extremely fine grain structure. For hardening, it must be raised to 1900 F. It will harden to 58 - 63 HRC. It is usually at the low end of this range, when tempered at 400 F

If the bearing is used in a corrosive or wet environment, it may be a type 440C hard martensitic stainless steel. This material is very magnetic and it is hard, but it is not as hard as chrome steel. It is about 58 HRC (Hardness Rockwell "C" scale). This material is only mildly corrosive resistant and will only respond to corrosion tests with slight pitting. It will eventually corrode in tap water and will not stand up to sea water at all. It is widely used as a premium bearing material and it is the top material for use in gaging products. See our article, Stainless Steel Balls, Type 440C Hardened for more information.

1100 series aluminum is commercially pure aluminum. It is a very light weight material that is a silvery white color, one of the natural base elements, and very ductile. Balls made of 1100 series aluminum are often used as closures. They are squashed or upset to permanently close a hole (an inside diameter). It is difficult to locate this material in less than mill-run quantities.

2017 aluminum is a copper alloy of aluminum that was originally developed for the manufacture of rivets. Its number one quality is that it can be safely cold-headed, which makes it an excellent choice as a material for precision balls. This is the aluminum alloy specified by Mil-B-1083, the generally accepted military specification for precision balls. This alloy has also been chosen by the AFBMA (Anti Friction Bearing Manufacturers Association as a standard ball material. This material is usually heat treated to the "T4" condition. This is not a good choice if the ball is to be anodized. High quality balls can be produced from this alloy.

2024 aluminum alloy is an aluminum copper alloy. It is a high strength material, widely used in aircraft. It can be cold headed. The tensile strength of this alloy can be improved by heat treating. This alloy is not a good choice for hard anodizing as the segregation of copper will form voids and can even cause incineration of the metal during the anodizing process.

6061 Aluminum alloy is a widely used, readily available, aluminum material. This material should never be cold headed--it can develop internal fissures that will lead to catastrophic failure. This alloy has much better machining qualities than 2017 alloy. This alloy is an excellent choice when the balls are to be hard anodized. The tensile strength of this alloy can be improved by heat treating. This aluminum alloy is relatively light at 0.098 lbs/ cu in.

It is very slightly magnetic. An aluminum bronze ball will roll towards a powerful magnet. This material is very resistant to sea water. Some alloys of this material can be heat treated to increase its hardness and tensile strength, but the hardening process reduces corrosive resistance. It is a very good electrical conductor.

A286 is one of the exotic Space Age materials. It has good wear properties. It is corrosion resistant. This material must be heat treated to develop its best physical properties. This material is very expensive. Very high quality balls can be produced from this material.

High quality steel balls of both chrome steel and hard stainless steel can be treated chemically to color the surface black. This black iron phosphate actually penetrates the surface so that the original size and surface quality is not affected. The most common application for this surface treatment is to provide identity for these balls. In some bearing and ball screw applications, two different size balls are used in the same device. The larger diameter balls are load bearing balls, and the smaller diameter black balls are used as spacer balls.

We manufacture and stock a large variety of brass balls. Brass balls are gold or bright yellow in color. The Standard alloy is 70-30, which is 70% copper and 30% zinc. The only major problem with the metallurgy of brass is segregation. This is due to the high melting point of copper (3000 F) and the low melting point of zinc (800 F). This material is quite ductile and very malleable. It is corrosive resistant to tap water, but does not stand up well in sea water. It is nonmagnetic, an excellent electrical conductor, and has excellent solder ability with soft solder, but may require chemical cleaning to remove an oxide layer. Brass has a hardness of less than 30 HRC, is very machinable, and it may be drilled and tapped easily. Brass is a relatively heavy material at .275 - .316 lbs/cu in (7.60 - 8.75 g / cc).

Naval Brass or Naval Bronze is very similar to brass, but has an addition of 0.5% to 1.0% tin. This small addition gives to material good corrosive resistance to sea water.Naval brass or bronze is a relatively heavy material at .305 lbs/ cu in. We will custom manufacture special alloys if the material is commercially available. Brass balls are precision ground and polished. They can be produced to AFBMA standards when required. We produce brass balls in all sizes from the sub-miniature to very large diameters.

We manufacture copper balls in the entire range of sizes from sub-miniature to several inches in diameter. Pure copper, as well as the many copper alloys, can be used to produce highly accurate precision balls.

Copper, usually oxygen free, has excellent electrical and heat conductivity, as well as good corrosion resistance in many harsh environments. It is nonmagnetic. It is sometimes annealed after all forming and machining is completed, to enhance its electrical properties. It is extremely malleable and ductile. It is very soft, but it is gummy and very difficult to machine, tending to gall easily. It is very solderable, and it is very corrosive resistant to sea water. Copper has a distinctly red color.

Diamond-impregnated balls are used to lap the spherical radius in ball valves. They usually have a stem or handle attached to facilitate holding during the lapping process. See our Diamond Impregnated Ball Lap page for more information.

An obvious use for gold is for jewelry. The nobility of gold meaning its resistance to corrosion and its good electrical conductivity leads to use in electrical applications. Gold has a high level of x-ray opacity and good bio-compatibility, which leads to its use as x-ray markers in medical applications. As gold is such an expensive material, we do not maintain a stock of gold balls.

Hevimet is usually sintered from powdered tungsten and powdered copper. Its very heavy weight makes it an alternative to lead in some uses. It is machinable, and unlike lead it is biologically safe. Ball's made of this material are used as counter-weights, and to add mass to mechanical structures.

High speed steel such as M50 and M10 or T15 are usually reserved for hot end bearings and high temperature ball screw applications. These materials are not corrosive resistant and will react to any of the corrosive tests. These materials are very hard. They will test up to 65 HRC. They will be strongly attracted by a magnet.

Inconel 7-18 is truly an aerospace metal. Inconel is hard and strong. It will continue to perform at high temperatures. It will also perform at temperatures so cold that hydrogen is a liquid. These low temperatures are so cold that there is a special word for it, cryogenic.

The highest quality is required for these aerospace oriented balls. In many cases, every single individual ball must have its own pedigree accompanying it. This will include the physical and chemical analysis of the individual bar of material, an ultrasonic examination, and the heat treating process that was performed on it. Along with this will be the diameter of the ball on three orthogonal axii and three polar charts of the roundness taken on three orthogonal axii.

A rocket engine using inconel balls depends on the integrity of each individual ball, making them crucial parts of the rocket engine. In addition, Inconel is highly corrosive resistant. It is precipitation hardened. This metal alloy must be heat-treated to develop its good physical properties. Care should be exercised in specifying the desired heat treatment as the furnace time for some processes may be very long and therefore, very expensive.

There are a number of different Monel alloys, a trademark of Special Metals Corp.. The basic alloy has a minimum of 23% copper and minimum of 60% nickel with small amounts of iron and manganese. This material is very tough but not very hard. It is not heat treatable. Monel is used in very corrosive environments. It is excellent in salt water applications such as valves for sea water. It is also used in the food processing industry.

We make Monel balls in a wide range of sizes. Due to its relatively soft nature, AFBMA grade 200 is the normal quality specification, although grade 100 can be achieved with some difficulty. It is relatively soft at about 38 HRC, and it is difficult to drill and tap.

MP35N finds use for check valve applications where no other metal could ever survive. In down hole control valves where the chemistry of the environment would eat a stainless steel ball, balls made of this material will last indefinitely.

This material is so tough that producing precision balls from it is a major problem. It cannot be cold headed at all. The forging temperatures are extreme. Like many of the exotic metals, MP35N can be lapped to a very high level of quality, once the spherical blank has been produced.

Platinum balls are widely used in high reliability electrical contacts. For this application, the platinum is alloyed with a small percentage of other elements. In the United States, it is usually alloyed with iridium; and in Europe, it is alloyed with nickel. These toughening and hardening metals have only a slight effect on the properties of the platinum. Platinum is the most noble of metals and is impervious to attack by most acids and bases. Platinum has one of the highest melting points of any metal (1768.3 C, 3214.9 F).

Unlike most other plastic balls, this material is a thermosetting plastic. This means that once this material has been heat cured in the mold, it will not melt again. You can raise the temperature of this plastic until it incinerates, but it will not melt. This material is much harder than any other commercially available plastic ball.

Ren 41 is an extremely tough high temperature nickel-chrome-molybdenum alloy. The machinability of this material is the very lowest of any commercially available alloy. But once the blank is machined, grinding and lapping are no problem. High quality balls can be produced from this material.

Tantalum balls or beads find frequent use as radiographic markers, because of their bio-compatibility. These balls can be implanted to form three dimensional markers for orthopedic evaluation after surgery. A ring of these radio graphically opaque markers are used at both ends of stints and shunts, providing a well defined address for the implanted devices. This material is used as an x-ray-opaque tracer in medical implants. An attached ball will define the position of a catheter. Tantalum is a very dense heavy metal (Ta) atomic weight is 180.947, density: 16.6g/cm^3. Unlike tungsten, it is very ductile and malleable. It will produce no reaction with either hydrochloric acid ( HCL) or nitric acid (HNO3). When Tantalum is implanted in a patient, it must be processed according to specification ASTM F560 (Medical Grade).

Titanium Balls are made in two popular titanium materials. The first is basically pure titanium. This material, grade 2, is widely used in medical applications, where it is frequently used in body implants because it is very bio-compatible. The second, and by far the most frequently used alloy is 6AL4V (6 % Aluminum, 4% Vanadium) titanium. This alloy is available in a variety of wire and bar forms for easy processing into precision balls. Satin finished titanium balls are used as calibration devices for optical inspection devices.

Tungsten has one of the highest melting points of any available metal. This is one of the heaviest metals. It is hard, tough, and non-magnetic. This metal is expensive and it is very difficult to machine, grind, or lap. Very high-quality balls can be produced from this material.

Aluminum Oxide is an almost white ceramic. Chemically it is Al2O3, also known as alumina balls or aloxite balls . This material is extremely hard. It has excellent electrical insulation properties. It is one of the least expensive and most widely used ceramic ball materials. It is very wear resistant, and it is very stiff with a young's modulus (YM) of elasticity of approximately 45,000,000 pounds per square inch. It can only be used in bearings at low speeds and very light loads. Star J and #3 are the alloys most frequently used for balls. They are very hard and wear-resistant.

Silicon Nitride (Si3N4) ceramic has become the standard ceramic ball material for hybrid Ball Bearings. This material is very hard, over 2000 Knoop, and very wear resistant. The weight of silicon nitride balls is only 40% of steel at 3.2 grams per cm (cubic centimeter) .

This material is hot isostatic pressed from 1 to 3 micro powder, has excellent fracture toughness even at elevated temperature, and ball quality as good as AFBMA grade-5 can be achieved on this material. Silicon nitride has excellent dielectric properties and extremely high resistivity (insulating properties).

ball mills

Ball Mills What Are These Machines and How Do They Work? Short flash video at bottom of page showing batch ball mill grinding in lab. May have to click on browser "Allow Active X blocked content" to play A Ball Mill grinds material by rotating a cylinder with steel grinding balls, causing the balls to fall back into the cylinder and onto the material to be ground. The rotation is usually between 4 to 20 revolutions per minute, depending upon the diameter of the mill. The larger the diameter, the slower the rotation. If the peripheral speed of the mill is too great, it begins to act like a centrifuge and the balls do not fall back, but stay on the perimeter of the mill. The point where the mill becomes a centrifuge is called the "Critical Speed", and ball mills usually operate at 65% to 75% of the critical speed. Ball Mills are generally used to grind material 1/4 inch and finer, down to the particle size of 20 to 75 microns. To achieve a reasonable efficiency with ball mills, they must be operated in a closed system, with oversize material continuously being recirculated back into the mill to be reduced. Various classifiers, such as screens, spiral classifiers, cyclones and air classifiers are used for classifying the discharge from ball mills. This formula calculates the critical speed of any ball mill. Most ball mills operate most efficiently between 65% and 75% of their critical speed. Photo of a 10 Ft diameter by 32 Ft long ball mill in a Cement Plant. Photo of a series of ball mills in a Copper Plant, grinding the ore for flotation. Image of cut away ball mill, showing material flow through typical ball mill. Flash viedo of Jar Drive and Batch Ball Mill grinding ore for testing Return To Crushing Info Page Contact Us Copyright 1994-2012 Mine-Engineer.Com All Rights Reserved

flsmidth global offices

FLSmidth provides sustainable productivity to the global mining and cement industries. We deliver market-leading engineering, equipment and service solutions that enable our customers to improve performance, drive down costs and reduce environmental impact. Our operations span the globe and we are close to 10,200 employees, present in more than 60 countries. In 2020, FLSmidth generated revenue of DKK 16.4 billion. MissionZero is our sustainability ambition towards zero emissions in mining and cement by 2030.

newmont corporation - operations & projects - global presence - north america - cripple creek & victor u.s

Location: 540 kilometers north west of Alice Springs, Northern Territory, Australia Metals Mined: Gold Mine Type: Underground Annual Gold Production*: 500 attributable Koz Date of First Production: 1983

Location: 16 kilometers from Boddington, Western AustraliaMetals Mined: Gold, copperMine Type: SurfaceAnnual Gold Production*: 703 attributable Koz2019 Annual Copper Production: 77 million attributable pounds35,000 attributable tonnesDate of First Production: 2009

The Ninga Mia Village, which houses around 100 aboriginal residents near our KCGM operation in Australia, was established in 1983 to provide more permanent accommodation for transient aboriginal people.

Newmont's Cripple Creek & Victor Mine (CC&V) is located in Teller County, Colorado, southwest of Pikes Peak. CC&V was formed as an operating company for mining operations in 1976, with mining in its Cresson Project starting in 1995.

CC&Vs modern, high-tech operations allow for responsible surface mining of various ore types. The majority of the ore is processed in a zero-discharge, valley-type, leach pad to recover gold and silver. In 2015 CC&V commissioned a rod, ball, and flotation mill which processes CC&Vs higher grade, non-oxidized ore.

The Cripple Creek gold deposits occur within a seven square mile (18 sq. km), 30 million year old, volcanic-intrusive complex that erupted and intruded through rocks that are over one billion years old.

Location: Near the towns of Cripple Creek and Victor Mine Type:4 surface operations Metals Mined: Gold and Silver Annual Gold Production*: 322 attributable Koz Date of First Production: 1976

The Cripple Creek Mining District was mined historically with underground operations until the 1960s. Mining activity then ceased for approximately a decade. Small-scale surface mining using the heap-leach gold recovery method began in 1971 followed by large-scale surface mining, which grew with the start of production at CC&Vs current mining operation, called the Cresson Project.

The Cresson is named for the historic underground mining operation of the same name. The Cresson is famous for the great gold find of the District, the Cresson Vug. A vug is a cavity in the rock, lined with crystals somewhat like a geode.

Engineering for the modern Cresson Mine began in 1993, and obtaining the various permits necessary to mine, ensuring compliance with applicable federal, State, and local requirements was completed in 1994.

For example, at CC&V, employees established an engagement program called SOS (See it, Own it, Solve it), which is a collaborative effort across all levels of the organization. The program encourages employees to improve our operations by speaking up when they see concerns, taking ownership of those concerns and helping identify solutions.

Newmont's success in building sustainable operations is based on our companys value of demonstrating leadership in safety, stewardship of the environment and social responsibility throughout all phases of the mining life-cycle.

Our employees devote countless hours to volunteerism in local communities. Broad-based community volunteer efforts contribute to projects such as community events, parks and recreation teams, volunteer fire departments and more.

We are particularly proud of our partnership with the Southern Teller County Focus Group to preserve historical sites throughout the mining district and provide safe public access to some of those areas. Five trails have been developed by the Focus Group on CC&V property. The Focus Group is responsible for maintenance of the trails and for signage that provides valuable information about the historical and modern mining in the area.

The intent of CC&Vs donation program is to support and contribute to the communities in which we live, play and work, and to provide visibility for the CC&V, our operations and our employees. Please see the Community Investment Program Guidelines for more information.

To apply for funding through Newmonts Community Investment Program, please complete the Community Investment Application. For questions or to submit a completed application, please contact Penny Riley at [emailprotected].

We use best practices to manage storm water, prevent pollution and protect wildlife. Careful monitoring of air, water quality and quantity, wildlife populations and habitat are key to protecting these resources. Monitoring reports are routinely and regularly submitted to various regulatory agencies.

Newmont's Cripple Creek and Victor (CC&V) sites, facilities and projects are subject to state and federal environmental regulations. Newmont has a staff of environmental professionals and technicians to manage these regulations appropriately and carry out the companys standards of environmental stewardship.

Colorados unique and varied natural landscape is an attribute that Newmont is committed to help protect for the enjoyment of future generations. In order to do this, planning for closure starts at the development stages of all projects. Additionally, concurrent reclamation is practiced throughout the mine life to revegetate and stabilize disturbed areas as soon as possible to provide habitat for wildlife and avoid erosion.

CC&V has organized noxious weed identification and management programs with local residents that raise awareness of weed problems in and around the city of Victor. The site has also worked for several years with the Cresson Elementary and Catamount Institute Young Environmental Stewards (YES) Clubs of the Pikes Peak Region to reclaim an abandoned gravel site now called Ceylon Beards in honor of the local resident who homesteaded there. The site has become an experiential learning station for local kids on planting ponderosa pine, building birdhouses and bat houses, creating small animal habitat, and studying macroinvertebrates.

Visitors are shuttled safely onto the mine site where they will see haul trucks, breathtaking vistas and industrial scale rock crushing equipment. This experience gives visitors an opportunity to witness socially and environmentally responsible mining activities at all stages of the mine lifecycle, from exploration, environmental monitoring and permitting, to production, ore processing and reclamation.

Public mine tours are offered twice daily from late May through September, except Thursdays. The charge is $8.50 per person, and all proceeds go to the Victor Lowell Thomas Museum to support annual activities. To learn more about making reservations, when to arrive and appropriate tour attire, visit www.VictorColorado.com or click the summer mine tour link on this page.

smart thermostat

Ideas to help educate and encourage customers to take simple steps to reduce their consumption. Learn more about: Manage My Account, My Energy Portal and SaveNow programs and rebates. Get Energy Tips and Peak Energy Day information. Learn about Smart Thermostats and Upcoming CPS Energy Events. Use our Energy Cost Calculator.

Enroll in our Budget Payment Plan, and well average your bills over the past year, add a small percentage to cover environmental factors and changing fuel costs, then charge you the resulting amount each month

Our Veterans Discount Program provides electric bill payment assistance to those who have significantly decreased abilities to regulate their core body temperatures due to severe burns received during combat

We offer help to those who provide emergency response for our country to include Firefighters and Police. Our First Responders with Burn Injuries Discount Program provides electric bill payment assistance to those who have significantly decreased abilities to regulate their core body temperatures due to severe burn injuries sustained in the course of providing first responder duties.

Now introducing the redesigned Construction Renovation web portal. The new portal is user-friendly and easy to navigate. Most importantly, it will allow most customers to create and manage their construction projects online, regardless of the project type.

The 2021 edition of CPS Energys Electric Service Standards presents for the convenience of Electrical Contractors, Architects, Engineers, and others, the current standards and requirements for electric service and meter installations. It supersedes all previous editions of the Electric Service Standards. These service standards are intended to supplement the City of San Antonio Electrical Code, National Electrical Code, and National Electrical Safety Code, and to establish certain requirements that are based on experience for maintaining safe and reliable service for CPS Energy Customers.

The Damage Prevention Bill for Texas (House Bill 2295) took effect October 1998, and is known as Utilities Code Title 5, Chapter 251. This law requires most facility owners to join a notification (or one call) center and requires excavators to call 48 hours prior to digging. It also requires any notification or one call center operating in Texas to share messages they receive between the notification centers. This provision is to ensure that excavators need only make one call to notify most buried facility owners. The Dig Safely program was introduced nationwide in June 1999. Its purpose is to help protect underground utility lines from damage by excavators, and protect excavators from the effects of damage to underground lines.

CPS Energy by way of its electric and natural gas service contract with the General Service Administration (GSA) in Washington D.C. is a federal contractor. Consequently, we are required to report our contracting activity with large, small, minority, service-disabled, veteran, historically underutilized, HUBZone, and woman-owned businesses.

CRU is dedicated to increasing community awareness of and enrollment in assistance programs, educating customers about energy efficiency and safety, and working directly with customers with unique needs.

Requests for a new streetlight in an unincorporated area or another incorporated city in the CPS Energy service delivery area should be made through the local homeowner association or municipal government office.

Our Corporate College Internship Program (CCIP), is designed to meet the industrys rapidly changing workforce needs by providing local San Antonio college students with public utility career experience.

This year marks our 75th anniversary of being owned by the city of San Antonio. Thats 75 years of providing safe, reliable, and affordable electric and gas services to the Greater San Antonio community.

A new substation, transmission line(s) and associated distribution lines, north of San Antonio near US 281 and FM 1863, will provide additional electric capacity and improve the reliability of electric services to homes and businesses in this area.

As the electric and natural gas utility in the Greater San Antonio area, we are committed to providing reliable power, so customers lights and natural gas turn on quickly, operate safely and remain affordable. As such, we are committed to improving infrastructure to ensure we provide the highest level of customer service and reliability to our community.

Ideas to help educate and encourage customers to take simple steps to reduce their consumption. Learn more about: Manage My Account, My Energy Portal and SaveNow programs and rebates. Get Energy Tips and Peak Energy Day information. Learn about Smart Thermostats and Upcoming CPS Energy Events. Use our Energy Cost Calculator.

Now introducing the redesigned Construction Renovation web portal. The new portal is user-friendly and easy to navigate. Most importantly, it will allow most customers to create and manage their construction projects online, regardless of the project type.

Our customers are learning about a variety of new ways to generate clean, efficient energy, including distributed generation, which is smaller-scale power production located where the power is consumed. CPS Energy can help you install a distributed generation (DG) system on your home or business.

CPS Energy's distribution system can facilitate the delivery of the variety of communication services offered today. With a streamlined pole attachment process, we're dedicated to partnering with companies to assist with speed-to-market processes for future technologies. CPS Energys Pole Attachment Services Office is the single point of contact for all who wish to attach infrastructure to our distribution poles.

The 2021 edition of CPS Energys Electric Service Standards presents for the convenience of Electrical Contractors, Architects, Engineers, and others, the current standards and requirements for electric service and meter installations. It supersedes all previous editions of the Electric Service Standards. These service standards are intended to supplement the City of San Antonio Electrical Code, National Electrical Code, and National Electrical Safety Code, and to establish certain requirements that are based on experience for maintaining safe and reliable service for CPS Energy Customers.

The Damage Prevention Bill for Texas (House Bill 2295) took effect October 1998, and is known as Utilities Code Title 5, Chapter 251. This law requires most facility owners to join a notification (or one call) center and requires excavators to call 48 hours prior to digging. It also requires any notification or one call center operating in Texas to share messages they receive between the notification centers. This provision is to ensure that excavators need only make one call to notify most buried facility owners. The Dig Safely program was introduced nationwide in June 1999. Its purpose is to help protect underground utility lines from damage by excavators, and protect excavators from the effects of damage to underground lines.

CPS Energy is the nations largest municipally owned energy utility providing both natural gas and electric service. We serve more than 840,750 electric customers and 352,585 natural gas customers in and around San Antonio, the nations seventh largest city.

To maintain the overall health of our infrastructure and utility system, we have to occasionally close roads to perform upgrades, maintenance and replacements. The road closures below are scheduled but on occasion, we are forced to close roads to make unscheduled repairs to our equipment.

We are proud to be a part of SA Climate Ready, working with UTSA and the City of San Antonio. This project is to develop a Climate Action and Adaptation Plan for the City of San Antonio - exploring both mitigation strategies, aiming to reduce or prevent the emission of GHGs, and adaptation strategies aming to prepare the community, municipal government operations, and other key sectors for the unavoidable impacts of climate change.

The RAC is made up of 21 members comprised of 11 appointees by the CPS Energy Board of Trustees, including Mayoral appointees and 10 City Council appointees. Members of the RAC will devote the necessary time and energy to learn about the utility business and the rate design function that allows utilities to recover their costs to provide service. This effort will help them understand and provide thoughtful input and perspectives regarding CPS Energys rate structure and rate design options.

We continue to fight to protect customers from excessive fuel and purchased power costs from the February 2021 Winter Storm Uri. Stay up to date by following us onFacebookandTwitter. More updates:NewsroomandStorm Updates.

We stand ready to help any customer in need. Our People First philosophy led us to suspend disconnects while our community bands together during this challenging time. If you are experiencing financial hardship, we urge you to contact us for help. Call us at 210-353-2222 or online at cpsenergy.com/assistance.

We encourage the use of a face-covering at any CPS Energy facility. Our customer service center hours are 7:45 am to 5:00 pm. Monday-Friday. If you have tested positive, or a family member has tested positive for COVID-19 in the last 14 days, please use our online tools or call 210-353-2222 for assistance. Please do not visit our customer service center if you have COVID-19 symptoms.

Through a Smart Thermostat, you agree to allow us to make adjustments to your thermostat during conservation events. This is when our system reaches peak demand. This will likely happen several times during the summer months and typically occurs between the hours of 3 p.m. and 7 p.m., Monday through Friday. During conservation events, you can opt out through your thermostat or smart phone app at any time and return to your normal settings. Conservation events dont occur very often, but they are crucial in managing the energy needs of our community.

how to operate a grinding circuit

How hard a ball mill operator has to work depends partly on himself, and partly on the kind of muck the mine sends over to the mill. In some plants, the ore may change two or three times a shift, and a ball mill operator has to keep on his toes.

Thats why it would be just as well for you, as a ball mill operator, to study out a few ways of doing your job easier and better, because there will be times, even in the best of mills, when youll run into a lot of trouble. Collected here you will find some practical suggestions, contributed by a number of good mill men, that might give you an idea or two that would help get around some of that trouble.

To be sure we understand each other, lets begin with the equipment. In a simple grinding circuit there will be a ball mill and a classifier. Some circuits, especially in large mills, have more units or two or three stages of grinding, but whatever is said here will apply to the complicated circuits as well as the simple ones.

The two types of ball mill in general use are the grate mill and the open-end mill. Most manufacturers make both kinds; the difference between them is that the grate mill has a steel grid clear across the discharge end, but the open-end mill has only an open trunnion at the discharge end, through which pulp flows freely. If you dont already know all about the inside of your ball mill and what it is supposed to do, it would be a good idea to ask the shift boss, the metallurgist, or the superintendent to tell you about it.

Mechanical classifiers make use of rakes, spirals, or a simple drag belt. For our purposes it doesnt matter which type you are working with, because you would handle them all in pretty much the same way.

In operation, you add water to the ball mill along with the ore. Flowing out of the ball mill, the ground ore pulp pours into the classifier pool, where the finished material is separated from the coarse sand. You do that by adding a lot more water to the pool, so that the finer sand overflows the weir and goes on to the next step (flotation perhaps), and the coarse sand settles to the classifier bottom and is raked back into the mill to be ground finer. You, the operator, aresupposed to control these actions in order to send on to the machines below you the right amount of ore, ground just fine enough, and with just the right amount of water with it.

To help you do this, and to make a. record of how things are going, you will have to take samples of the pulp regularly. Different mills have different ideas on sampling, but all of them take at least hourly samples of the classifier overflow. What it amounts to is weighing a certain volume of the pulp to determine its density. Higher density means thicker pulp and usually coarser sand. Lower density means thinner pulp and finer sand. The shift boss will tell you what the density ought to be, and it will be up to you to hold it there.

You may also have to take density samples of the ball mill discharge, which runs a lot thicker than the classifier overflow, and some mills also expect you to take measured samples of the ball-mill feed and weigh them.

Another sample you may take is one for pH, which is a term that takes a little explaining. You can find out exactly what pH means from a chemistry book if you want to; but for all practical purposes, it is enough to know that pH is a number that tells you how much acid or alkali there is in the pulp. A pH of 7 is alkaline.

If you add acid, the pH goes down below 7; if you add an alkali like lime, the pH will go up, say to 9 or 10, depending on how much lime you add. In any case, you can bank on it that if the brass hats want you to watch the pH at all, they have good reasons for wanting you to hold it steady.

You may also have the job of adding balls to the mill each shift. The shift boss tells you how many or what weight, and you put them in. Drop them into the scoop if you have a grate mill, or put them in through the discharge trunnion if it is an open-end mill.

The controls you will have to work with are given in Table I, and are also indicated in the drawing. As to which one of these controls is most important, mill men dont all agree. Probably it depends on what kind of ore you are grinding. Most good operators, though, say that the classifier water valve should be the first one to adjust, because it controls directly the kind of finished material you send on down the line to the next man.

The most important point is this: You cannot adjust any one of these controls without paying some attention to the other two. For example, if you change the feed rate, you will probably have to reset the two water valves. They all work together. In fact, the whole grinding circuit acts like a team of horses, and as thetime at first.

In Table II you will find some suggestions on what to look for to help you decide how to use these controls. In the column headed if you find, there are set down the things youll run into if something is wrong with the circuit. That is, if the ball-mill feed gets finer than it usuallyis, the top line tells you what to expect and what to do. But dont think you have to do all these things all the time. Do only as much as you are sure you have to do.

The classifier overflow is really the most important spot in the circuit, because whatever comes over that weir is out of your hands, and your work will be judged by how good a product it is. Most operators believe that if there is any change in setting to be made, the density of the classifier overflow is where you make it first. Remember, more water to the classifier means thinner pulp and finer overflow; less water means thicker pulp and coarser overflow.

The matter of feed to the ball mill brings up a point that is important in keeping you out of trouble. You can find out by asking the old- timers how each kind of ore is going to act when it hits the mill, and if youfor each change as it comes along.

For example, suppose you are working in a lead-zinc flotation mill where there are two kinds of ore one that is coarse and low grade, and another that is finer and higher grade. Keep the feed to the ball mill lower when the coarse stuff comes along, because it takes longer to grind and you dont want to overload the mill. Then when the fine muck shows up, increase the feed and also run the classifier density higher. That will throw the high grade over into the flotation cells where it belongs.

You see, the high-grade mineral is heavier than the low grade, and it takes a little higher density in the classifier to lift it out. If you carry a low density, too much lead and zinc mineral keeps going back into the ball mill, and eventually may be ground into slime and lost altogether. Doing extralittle things like this is what marks a really good operator, and you can learn these things only by study and asking questions.

Keep ahead of trouble is good advice for flotation operators, and it is just as good for bail-mill men. A good operator can take care of even big changes in muck so smoothly and easily that if you were watching him, youd never know anything was running differently.

On the other hand, consider Joe Blow, the Wonder Boy. Thats him down there sitting on the rail near the ball mill, swinging his heels and probably wondering whatever happened to that little blonde hasher over at the Greasy Spoon. Suddenly Joe looks up. He has heard a splashing sound that doesnt belong there. The ball mill is strangely quiet. Joe looks at the feed box, and finds pulp pouring out on the floor.

Joe can tell right away what has happened. The mill has been overloaded and the grate has plugged. Quick as a flash, Joe races around and shuts the feed off, then whips open the valve pouring water into the mill. Hes fast; he wants action.

He gets it. The mill comes unstuck with a vengeance and belches sand into the classifier like a tidal wave. Joe, the dope, flushes water into the classifier, too, and you can almost hear it groan as the rakes get buried. The flotation man down below is tearing his hair and spinning valves. What he says about Joe blisters the paint on the concentrate launders, but Joe cant hear him. Joe is up under the mill shovellingcleaned up before the shifter comes.

Watching the mill discharge (2) will tell you what goes on inside the mill. Some operators note how high on the side of the discharge flange the wave of pulp is carried when the mill is running right. Then if the wave runs higher or lower than that, they know something is wrong.

If the mill is low on muck, (3) it rattles and bangs like a boiler factory, and a lot of good steel goes to waste. But if the mill is too full of muck, you can hardly hear it. Keep your ear peeled for the sound of the mill that you know is right.

Many operators feel the classifier overflow (6) by nibbling their fingers together with their hands in the stream, and with a little experience, you can tell pretty accurately whether or not the overflow is fine enough.

The amp-meter (4) is really as good a guide to the condition of the mill as the sound or the discharge. It tells you how much power the mill drive motor is drawing, but remember that if you overload the mill, or if you underload it, it draws less power.

You check on the circulating load (7) by watching the height of the sand on the rakes or spiral flights as they push it back to the mill feed launder. The shift boss will tell you about how high the sand ought to come.

What was wrong? He shouldnt have let the mill plug in the first place. But suppose it plugged anyway, he should have cut off the feed all right, but he should also have shut down the classifier, and increased the head water only a little. Then he should have cut down on the classifier water and then increased it, little by little, when the mill opened up. He should have done his best to keep things balanced instead of slamming everything out of adjustment at once. Well, hell learn. He will, or the boss will murder him some dark night.

Now, just because all these things to look for and to do have been put down in a table, dont think you ought to walk your shift carrying this operating manual in one hand and a density sample can in the other. It is no use trying to run a mill out of a cookbook. But what we did want to do was to set these things down here so you could think about them, and keep thinking about them, while you are working.

Just go at the problem the way things are arranged in the table. When something in the circuit begins to change, make sure you know exactly what is happening; then ask yourself what is causing it. Then, when you have answered that question, decide what to do about it. Think out each thing you do, and dont do things in a rush or without knowing why you are doing them. Dont be a Joe Blow, in other words.

One thing more, and a very important thing: When you do make a change, allow a little time, say 15 or 20 minutes, for the effect to show up before you make another change. Dont over-control. For instance, if the density in the classifier is up a little and you add more water, dont expect the density to change right away, and dont go back and open the valve even wider just because nothing seems to have happened. It will; just wait a while. A superoperator who cant let well enough alone gets on everybodys nerves.

In starting the grinding circuit after anything but a very short shut spitars enough to clear the samepacked on the tank bottom, start the classifier overflow pump, then start the classifier, and after that, the ball mill. But dont throw in all these switches at once. Youll get the electricians down on you if you do. Keep the water fed to the circuit down low until the load builds up a little; then set the valve hand wheels at about thepoint they should be for normal operation. You can check on this setting by marking one spot on the rim of the wheel and counting turns, or by counting exposed threads on the valve stem. Dont forget to lower the classifier rakes again as the load builds up.

In shutting down the mill, cut off the feed a few minutes before the shutdown is due. That will give time to grind out some of the circulating load and will make starting easier. Then when you are ready to stop, shut down the mill, then the classifier (raise the rakes), then the pump for the classifier overflow, if there is one.

If the power fails suddenly, shut off the water valves and raise the classifier rakes. And for goodness sake, dont forget to shut off any drip cans or siphon feeders of pine oil or other reagent you may have running somewhere in the circuit.

So far as mechanical trouble goes, there will probably be little of that if the equipment is reasonably good. Ball mills spring leaks from time to time because the bolts holding in the liner plates work loose. If a leak develops near the discharge end of the mill, shut down right away and fix it. This is especially true of an open-end mill. The point is that you dont want sand getting into theout in short order.

Now a word about safety, a subject that I am putting last because I want to leave it first in your minds. Whatever else you do, dont go poking aimlessly around the mill or the classifier, sticking your nose or your fingers in here and there to see how the machinery works. I wouldnt make that statement if I hadnt seen a man or two doing just that. Nor have I forgotten the time I was routed out of bed at two a.m. to help bandage a man whose right-hand fingers had just been taken off by the ball-mill scoop as effectively, though not as neatly, as a surgeon could have done it.He had been just poking around, too. Remember your company, and your country, need you on that ball-mill floor, and you wouldnt be happy holding down a hospital bed these days. So just be careful.

This Public DomainRobert Ramsey article is based in large part on experiences and opinions generously supplied by the following mill men: Clyde Simpson, Bagdad Copper Co., Hillside, Ariz.; E. J. Duggan and M. E. Kennedy, Climax Molybdenum Co., Climax, Colo.; John Palecek, Keystone Copper Corp., Copperopolis, Calif.; Frank M. McKinley, Bunker Hill & Sullivan M. & C. Co., Kellogg, Idaho; Malcolm Black, Wright-Hargreaves Mines, Ltd., Kirkland Lake, Ont.; and the concentrator staffs at Hudson Bay Mining & Smelting Co., Flin Flon, Manitoba, and Sherritt Gordon Mines, Ltd., Sherridon, Manitoba.https://archive.org/details/malozemoffmining00platrich

ball mill - an overview | sciencedirect topics

The ball mill accepts the SAG or AG mill product. Ball mills give a controlled final grind and produce flotation feed of a uniform size. Ball mills tumble iron or steel balls with the ore. The balls are initially 510 cm diameter but gradually wear away as grinding of the ore proceeds. The feed to ball mills (dry basis) is typically 75 vol.-% ore and 25% steel.

The ball mill is operated in closed circuit with a particle-size measurement device and size-control cyclones. The cyclones send correct-size material on to flotation and direct oversize material back to the ball mill for further grinding.

Grinding elements in ball mills travel at different velocities. Therefore, collision force, direction and kinetic energy between two or more elements vary greatly within the ball charge. Frictional wear or rubbing forces act on the particles, as well as collision energy. These forces are derived from the rotational motion of the balls and movement of particles within the mill and contact zones of colliding balls.

By rotation of the mill body, due to friction between mill wall and balls, the latter rise in the direction of rotation till a helix angle does not exceed the angle of repose, whereupon, the balls roll down. Increasing of rotation rate leads to growth of the centrifugal force and the helix angle increases, correspondingly, till the component of weight strength of balls become larger than the centrifugal force. From this moment the balls are beginning to fall down, describing during falling certain parabolic curves (Figure 2.7). With the further increase of rotation rate, the centrifugal force may become so large that balls will turn together with the mill body without falling down. The critical speed n (rpm) when the balls are attached to the wall due to centrifugation:

where Dm is the mill diameter in meters. The optimum rotational speed is usually set at 6580% of the critical speed. These data are approximate and may not be valid for metal particles that tend to agglomerate by welding.

The degree of filling the mill with balls also influences productivity of the mill and milling efficiency. With excessive filling, the rising balls collide with falling ones. Generally, filling the mill by balls must not exceed 3035% of its volume.

The mill productivity also depends on many other factors: physical-chemical properties of feed material, filling of the mill by balls and their sizes, armor surface shape, speed of rotation, milling fineness and timely moving off of ground product.

where b.ap is the apparent density of the balls; l is the degree of filling of the mill by balls; n is revolutions per minute; 1, and 2 are coefficients of efficiency of electric engine and drive, respectively.

A feature of ball mills is their high specific energy consumption; a mill filled with balls, working idle, consumes approximately as much energy as at full-scale capacity, i.e. during grinding of material. Therefore, it is most disadvantageous to use a ball mill at less than full capacity.

The ball mill is a tumbling mill that uses steel balls as the grinding media. The length of the cylindrical shell is usually 11.5 times the shell diameter (Figure 8.11). The feed can be dry, with less than 3% moisture to minimize ball coating, or slurry containing 2040% water by weight. Ball mills are employed in either primary or secondary grinding applications. In primary applications, they receive their feed from crushers, and in secondary applications, they receive their feed from rod mills, AG mills, or SAG mills.

Ball mills are filled up to 40% with steel balls (with 3080mm diameter), which effectively grind the ore. The material that is to be ground fills the voids between the balls. The tumbling balls capture the particles in ball/ball or ball/liner events and load them to the point of fracture.

When hard pebbles rather than steel balls are used for the grinding media, the mills are known as pebble mills. As mentioned earlier, pebble mills are widely used in the North American taconite iron ore operations. Since the weight of pebbles per unit volume is 3555% of that of steel balls, and as the power input is directly proportional to the volume weight of the grinding medium, the power input and capacity of pebble mills are correspondingly lower. Thus, in a given grinding circuit, for a certain feed rate, a pebble mill would be much larger than a ball mill, with correspondingly a higher capital cost. However, the increase in capital cost is justified economically by a reduction in operating cost attributed to the elimination of steel grinding media.

In general, ball mills can be operated either wet or dry and are capable of producing products in the order of 100m. This represents reduction ratios of as great as 100. Very large tonnages can be ground with these ball mills because they are very effective material handling devices. Ball mills are rated by power rather than capacity. Today, the largest ball mill in operation is 8.53m diameter and 13.41m long with a corresponding motor power of 22MW (Toromocho, private communications).

Planetary ball mills. A planetary ball mill consists of at least one grinding jar, which is arranged eccentrically on a so-called sun wheel. The direction of movement of the sun wheel is opposite to that of the grinding jars according to a fixed ratio. The grinding balls in the grinding jars are subjected to superimposed rotational movements. The jars are moved around their own axis and, in the opposite direction, around the axis of the sun wheel at uniform speed and uniform rotation ratios. The result is that the superimposition of the centrifugal forces changes constantly (Coriolis motion). The grinding balls describe a semicircular movement, separate from the inside wall, and collide with the opposite surface at high impact energy. The difference in speeds produces an interaction between frictional and impact forces, which releases high dynamic energies. The interplay between these forces produces the high and very effective degree of size reduction of the planetary ball mill. Planetary ball mills are smaller than common ball mills, and are mainly used in laboratories for grinding sample material down to very small sizes.

Vibration mill. Twin- and three-tube vibrating mills are driven by an unbalanced drive. The entire filling of the grinding cylinders, which comprises the grinding media and the feed material, constantly receives impulses from the circular vibrations in the body of the mill. The grinding action itself is produced by the rotation of the grinding media in the opposite direction to the driving rotation and by continuous head-on collisions of the grinding media. The residence time of the material contained in the grinding cylinders is determined by the quantity of the flowing material. The residence time can also be influenced by using damming devices. The sample passes through the grinding cylinders in a helical curve and slides down from the inflow to the outflow. The high degree of fineness achieved is the result of this long grinding procedure. Continuous feeding is carried out by vibrating feeders, rotary valves, or conveyor screws. The product is subsequently conveyed either pneumatically or mechanically. They are basically used to homogenize food and feed.

CryoGrinder. As small samples (100 mg or <20 ml) are difficult to recover from a standard mortar and pestle, the CryoGrinder serves as an alternative. The CryoGrinder is a miniature mortar shaped as a small well and a tightly fitting pestle. The CryoGrinder is prechilled, then samples are added to the well and ground by a handheld cordless screwdriver. The homogenization and collection of the sample is highly efficient. In environmental analysis, this system is used when very small samples are available, such as small organisms or organs (brains, hepatopancreas, etc.).

The vibratory ball mill is another kind of high-energy ball mill that is used mainly for preparing amorphous alloys. The vials capacities in the vibratory mills are smaller (about 10 ml in volume) compared to the previous types of mills. In this mill, the charge of the powder and milling tools are agitated in three perpendicular directions (Fig. 1.6) at very high speed, as high as 1200 rpm.

Another type of the vibratory ball mill, which is used at the van der Waals-Zeeman Laboratory, consists of a stainless steel vial with a hardened steel bottom, and a single hardened steel ball of 6 cm in diameter (Fig. 1.7).

The mill is evacuated during milling to a pressure of 106 Torr, in order to avoid reactions with a gas atmosphere.[44] Subsequently, this mill is suitable for mechanical alloying of some special systems that are highly reactive with the surrounding atmosphere, such as rare earth elements.

A ball mill is a relatively simple apparatus in which the motion of the reactor, or of a part of it, induces a series of collisions of balls with each other and with the reactor walls (Suryanarayana, 2001). At each collision, a fraction of the powder inside the reactor is trapped between the colliding surfaces of the milling tools and submitted to a mechanical load at relatively high strain rates (Suryanarayana, 2001). This load generates a local nonhydrostatic mechanical stress at every point of contact between any pair of powder particles. The specific features of the deformation processes induced by these stresses depend on the intensity of the mechanical stresses themselves, on the details of the powder particle arrangement, that is on the topology of the contact network, and on the physical and chemical properties of powders (Martin et al., 2003; Delogu, 2008a). At the end of any given collision event, the powder that has been trapped is remixed with the powder that has not undergone this process. Correspondingly, at any instant in the mechanical processing, the whole powder charge includes fractions of powder that have undergone a different number of collisions.

The individual reactive processes at the perturbed interface between metallic elements are expected to occur on timescales that are, at most, comparable with the collision duration (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b). Therefore, unless the ball mill is characterized by unusually high rates of powder mixing and frequency of collisions, reactive events initiated by local deformation processes at a given collision are not affected by a successive collision. Indeed, the time interval between successive collisions is significantly longer than the time period required by local structural perturbations for full relaxation (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b).

These few considerations suffice to point out the two fundamental features of powder processing by ball milling, which in turn govern the MA processes in ball mills. First, mechanical processing by ball milling is a discrete processing method. Second, it has statistical character. All of this has important consequences for the study of the kinetics of MA processes. The fact that local deformation events are connected to individual collisions suggests that absolute time is not an appropriate reference quantity to describe mechanically induced phase transformations. Such a description should rather be made as a function of the number of collisions (Delogu et al., 2004). A satisfactory description of the MA kinetics must also account for the intrinsic statistical character of powder processing by ball milling. The amount of powder trapped in any given collision, at the end of collision is indeed substantially remixed with the other powder in the reactor. It follows that the same amount, or a fraction of it, could at least in principle be trapped again in the successive collision.

This is undoubtedly a difficult aspect to take into account in a mathematical description of MA kinetics. There are at least two extreme cases to consider. On the one hand, it could be assumed that the powder trapped in a given collision cannot be trapped in the successive one. On the other, it could be assumed that powder mixing is ideal and that the amount of powder trapped at a given collision has the same probability of being processed in the successive collision. Both these cases allow the development of a mathematical model able to describe the relationship between apparent kinetics and individual collision events. However, the latter assumption seems to be more reliable than the former one, at least for commercial mills characterized by relatively complex displacement in the reactor (Manai et al., 2001, 2004).

A further obvious condition for the successful development of a mathematical description of MA processes is the one related to the uniformity of collision regimes. More specifically, it is highly desirable that the powders trapped at impact always experience the same conditions. This requires the control of the ball dynamics inside the reactor, which can be approximately obtained by using a single milling ball and an amount of powder large enough to assure inelastic impact conditions (Manai et al., 2001, 2004; Delogu et al., 2004). In fact, the use of a single milling ball avoids impacts between balls, which have a remarkable disordering effect on the ball dynamics, whereas inelastic impact conditions permit the establishment of regular and periodic ball dynamics (Manai et al., 2001, 2004; Delogu et al., 2004).

All of the above assumptions and observations represent the basis and guidelines for the development of the mathematical model briefly outlined in the following. It has been successfully applied to the case of a Spex Mixer/ Mill mod. 8000, but the same approach can, in principle, be used for other ball mills.

The Planetary ball mills are the most popular mills used in MM, MA, and MD scientific researches for synthesizing almost all of the materials presented in Figure 1.1. In this type of mill, the milling media have considerably high energy, because milling stock and balls come off the inner wall of the vial (milling bowl or vial) and the effective centrifugal force reaches up to 20 times gravitational acceleration.

The centrifugal forces caused by the rotation of the supporting disc and autonomous turning of the vial act on the milling charge (balls and powders). Since the turning directions of the supporting disc and the vial are opposite, the centrifugal forces alternately are synchronized and opposite. Therefore, the milling media and the charged powders alternatively roll on the inner wall of the vial, and are lifted and thrown off across the bowl at high speed, as schematically presented in Figure 2.17.

However, there are some companies in the world who manufacture and sell number of planetary-type ball mills; Fritsch GmbH (www.fritsch-milling.com) and Retsch (http://www.retsch.com) are considered to be the oldest and principal companies in this area.

Fritsch produces different types of planetary ball mills with different capacities and rotation speeds. Perhaps, Fritsch Pulverisette P5 (Figure 2.18(a)) and Fritsch Pulverisette P6 (Figure 2.18(b)) are the most popular models of Fritsch planetary ball mills. A variety of vials and balls made of different materials with different capacities, starting from 80ml up to 500ml, are available for the Fritsch Pulverisette planetary ball mills; these include tempered steel, stainless steel, tungsten carbide, agate, sintered corundum, silicon nitride, and zirconium oxide. Figure 2.19 presents 80ml-tempered steel vial (a) and 500ml-agate vials (b) together with their milling media that are made of the same materials.

Figure 2.18. Photographs of Fritsch planetary-type high-energy ball mill of (a) Pulverisette P5 and (b) Pulverisette P6. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.19. Photographs of the vials used for Fritsch planetary ball mills with capacity of (a) 80ml and (b) 500ml. The vials and the balls shown in (a) and (b) are made of tempered steel agate materials, respectively (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

More recently and in year 2011, Fritsch GmbH (http://www.fritsch-milling.com) introduced a new high-speed and versatile planetary ball mill called Planetary Micro Mill PULVERISETTE 7 (Figure 2.20). The company claims this new ball mill will be helpful to enable extreme high-energy ball milling at rotational speed reaching to 1,100rpm. This allows the new mill to achieve sensational centrifugal accelerations up to 95 times Earth gravity. They also mentioned that the energy application resulted from this new machine is about 150% greater than the classic planetary mills. Accordingly, it is expected that this new milling machine will enable the researchers to get their milled powders in short ball-milling time with fine powder particle sizes that can reach to be less than 1m in diameter. The vials available for this new type of mill have sizes of 20, 45, and 80ml. Both the vials and balls can be made of the same materials, which are used in the manufacture of large vials used for the classic Fritsch planetary ball mills, as shown in the previous text.

Retsch has also produced a number of capable high-energy planetary ball mills with different capacities (http://www.retsch.com/products/milling/planetary-ball-mills/); namely Planetary Ball Mill PM 100 (Figure 2.21(a)), Planetary Ball Mill PM 100 CM, Planetary Ball Mill PM 200, and Planetary Ball Mill PM 400 (Figure 2.21(b)). Like Fritsch, Retsch offers high-quality ball-milling vials with different capacities (12, 25, 50, 50, 125, 250, and 500ml) and balls of different diameters (540mm), as exemplified in Figure 2.22. These milling tools can be made of hardened steel as well as other different materials such as carbides, nitrides, and oxides.

Figure 2.21. Photographs of Retsch planetary-type high-energy ball mill of (a) PM 100 and (b) PM 400. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.22. Photographs of the vials used for Retsch planetary ball mills with capacity of (a) 80ml, (b) 250ml, and (c) 500ml. The vials and the balls shown are made of tempered steel (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

Both Fritsch and Retsch companies have offered special types of vials that allow monitoring and measure the gas pressure and temperature inside the vial during the high-energy planetary ball-milling process. Moreover, these vials allow milling the powders under inert (e.g., argon or helium) or reactive gas (e.g., hydrogen or nitrogen) with a maximum gas pressure of 500kPa (5bar). It is worth mentioning here that such a development made on the vials design allows the users and researchers to monitor the progress tackled during the MA and MD processes by following up the phase transformations and heat realizing upon RBM, where the interaction of the gas used with the freshly created surfaces of the powders during milling (adsorption, absorption, desorption, and decomposition) can be monitored. Furthermore, the data of the temperature and pressure driven upon using this system is very helpful when the ball mills are used for the formation of stable (e.g., intermetallic compounds) and metastable (e.g., amorphous and nanocrystalline materials) phases. In addition, measuring the vial temperature during blank (without samples) high-energy ball mill can be used as an indication to realize the effects of friction, impact, and conversion processes.

More recently, Evico-magnetics (www.evico-magnetics.de) has manufactured an extraordinary high-pressure milling vial with gas-temperature-monitoring (GTM) system. Likewise both system produced by Fritsch and Retsch, the developed system produced by Evico-magnetics, allowing RBM but at very high gas pressure that can reach to 15,000kPa (150bar). In addition, it allows in situ monitoring of temperature and of pressure by incorporating GTM. The vials, which can be used with any planetary mills, are made of hardened steel with capacity up to 220ml. The manufacturer offers also two-channel system for simultaneous use of two milling vials.

Using different ball mills as examples, it has been shown that, on the basis of the theory of glancing collision of rigid bodies, the theoretical calculation of tPT conditions and the kinetics of mechanochemical processes are possible for the reactors that are intended to perform different physicochemical processes during mechanical treatment of solids. According to the calculations, the physicochemical effect of mechanochemical reactors is due to short-time impulses of pressure (P = ~ 10101011 dyn cm2) with shift, and temperature T(x, t). The highest temperature impulse T ~ 103 K are caused by the dry friction phenomenon.

Typical spatial and time parameters of the impactfriction interaction of the particles with a size R ~ 104 cm are as follows: localization region, x ~ 106 cm; time, t ~ 108 s. On the basis of the obtained theoretical results, the effect of short-time contact fusion of particles treated in various comminuting devices can play a key role in the mechanism of activation and chemical reactions for wide range of mechanochemical processes. This role involves several aspects, that is, the very fact of contact fusion transforms the solid phase process onto another qualitative level, judging from the mass transfer coefficients. The spatial and time characteristics of the fused zone are such that quenching of non-equilibrium defects and intermediate products of chemical reactions occurs; solidification of the fused zone near the contact point results in the formation of a nanocrystal or nanoamor- phous state. The calculation models considered above and the kinetic equations obtained using them allow quantitative ab initio estimates of rate constants to be performed for any specific processes of mechanical activation and chemical transformation of the substances in ball mills.

There are two classes of ball mills: planetary and mixer (also called swing) mill. The terms high-speed vibration milling (HSVM), high-speed ball milling (HSBM), and planetary ball mill (PBM) are often used. The commercial apparatus are PBMs Fritsch P-5 and Fritsch Pulverisettes 6 and 7 classic line, the Retsch shaker (or mixer) mills ZM1, MM200, MM400, AS200, the Spex 8000, 6750 freezer/mill SPEX CertiPrep, and the SWH-0.4 vibrational ball mill. In some instances temperature controlled apparatus were used (58MI1); freezer/mills were used in some rare cases (13MOP1824).

The balls are made of stainless steel, agate (SiO2), zirconium oxide (ZrO2), or silicon nitride (Si3N). The use of stainless steel will contaminate the samples with steel particles and this is a problem both for solid-state NMR and for drug purity.

However, there are many types of ball mills (see Chapter 2 for more details), such as drum ball mills, jet ball mills, bead-mills, roller ball mills, vibration ball mills, and planetary ball mills, they can be grouped or classified into two types according to their rotation speed, as follows: (i) high-energy ball mills and (ii) low-energy ball mills. Table 3.1 presents characteristics and comparison between three types of ball mills (attritors, vibratory mills, planetary ball mills and roller mills) that are intensively used on MA, MD, and MM techniques.

In fact, choosing the right ball mill depends on the objectives of the process and the sort of materials (hard, brittle, ductile, etc.) that will be subjecting to the ball-milling process. For example, the characteristics and properties of those ball mills used for reduction in the particle size of the starting materials via top-down approach, or so-called mechanical milling (MM process), or for mechanically induced solid-state mixing for fabrications of composite and nanocomposite powders may differ widely from those mills used for achieving mechanically induced solid-state reaction (MISSR) between the starting reactant materials of elemental powders (MA process), or for tackling dramatic phase transformation changes on the structure of the starting materials (MD). Most of the ball mills in the market can be employed for different purposes and for preparing of wide range of new materials.

Martinez-Sanchez et al. [4] have pointed out that employing of high-energy ball mills not only contaminates the milled amorphous powders with significant volume fractions of impurities that come from milling media that move at high velocity, but it also affects the stability and crystallization properties of the formed amorphous phase. They have proved that the properties of the formed amorphous phase (Mo53Ni47) powder depends on the type of the ball-mill equipment (SPEX 8000D Mixer/Mill and Zoz Simoloter mill) used in their important investigations. This was indicated by the high contamination content of oxygen on the amorphous powders prepared by SPEX 8000D Mixer/Mill, when compared with the corresponding amorphous powders prepared by Zoz Simoloter mill. Accordingly, they have attributed the poor stabilities, indexed by the crystallization temperature of the amorphous phase formed by SPEX 8000D Mixer/Mill to the presence of foreign matter (impurities).

asarco milling

SAG mills use larger pieces of ore to break up the smaller pieces (autogenous does it by itself). The larger pieces break down as well. To help the process along, eight-inch-diameter steel balls are added to the rocks as they tumble inside the rotating mill (semi-autogenous gets some help from the steel balls). The two SAG mills in the Mission South Mill each have two 3,000 horsepower electric motors. They can rotate in either direction which helps even out the wear on the steel liners inside the mill.

When the rocks are about 3/8-inch or smaller, they are fed as a slurry into the two ball mills. Each ball mill is turned by a single 3,000 horsepower electric motor. These mills contain literally hundreds of thousands of three-inch diameter steel balls that pulverize the ore until it is like fine sand or face powder. Only then are the copper minerals broken free of the rest of the rock to be separated by flotation.

Air is blown into the tank and the mixture is vigorously agitated like a high-speed blender. Rising bubbles carry the copper minerals up and over the edge of the flotation tank. The bubbles break soon after they flow over the edge. The copper minerals are then ground up even finer and purified by another flotation process.

The dried copper concentrate of about 28 percent copper is shipped to the smelter. It represents less than one percent of the material removed from the mine. Concentrate is just a fine powder of the mineral chalcopyrite which is a naturally occurring compound of copper, iron, and sulfur.

The material that sinks in the first flotation cell goes on to two more flotation cells to recover as much copper as possible. What doesnt float is called tailings because it goes out the tail end of the flotation circuit. About 80 percent of the water used in the milling process is reclaimed and re-used. The rest is used to keep the tailings damp and to prevent wind-blown dust.

ball mill: operating principles, components, uses, advantages and

A ball mill also known as pebble mill or tumbling mill is a milling machine that consists of a hallow cylinder containing balls; mounted on a metallic frame such that it can be rotated along its longitudinal axis. The balls which could be of different diameter occupy 30 50 % of the mill volume and its size depends on the feed and mill size. The large balls tend to break down the coarse feed materials and the smaller balls help to form fine product by reducing void spaces between the balls. Ball mills grind material by impact and attrition.

Several types of ball mills exist. They differ to an extent in their operating principle. They also differ in their maximum capacity of the milling vessel, ranging from 0.010 liters for planetary ball mills, mixer mills, or vibration ball mills to several 100 liters for horizontal rolling ball mills.

Im grateful for the information about using a ball mill for pharmaceutical products as it produces very fine powder. My friend is working for a pharmaceutical company and this is a good article to share with her. Its good to know that ball mills are suitable for milling toxic materials since they can be used in a completely enclosed for. Thanks for the tips!

major mines & projects | cobre panama mine

The mineralised zones on the Cobre Panam property are examples of copper-gold-molybdenum porphyry deposits. Supergene mineralisation Oxidation of sulphides near the surface weathering profile has leached copper from the present-day saprolite. Copper has been weakly and irregularly re-precipitated in the upper zones of the deposits. Secondary sulphides are dominantly chalcocite with minor covellite and rare native copper. These secondary minerals occur as fracture infills, coatings on primary sulphide minerals and disseminations. Where these sulphides have been oxidised, malachite is the main copper oxide mineral.Notably absent across the majority of the Cobre Panam deposits is the presence of a significant zone of enrichment. It is interpreted that this is likely due to removal by erosion of a previously welldeveloped phyllic alteration zone which may have overlain these deposits. Phyllic alteration zones are suitable host rocks for re-precipitation of copper as they can sufficiently neutralise the acidic fluids required for leaching. A well-developed phyllic alteration zone is developed at Brazo, which accompanies a significant secondary copper sulphide mineralisation zone.Hypogene mineralisation Hypogene mineralisation within the granodiorite and various porphyry lithologies consists of disseminated sulphides, micro-veinlets, fracture fillings, veinlets and quartz-sulphide stockworks. Copper mineralisation occurs as chalcopyrite with lesser bornite. Throughout all deposits the proportion of bornite relative to chalcopyrite appears to increase with depth. Molybdenite is present in quartz B veinlets (Gustafson and Hunt, 1975). Pyrite is ubiquitous but the tenor increases in association with phyllic and chlorite-silica alteration compared to other alteration assemblages. Within the phyllic alteration zone, pyrite occurs as disseminations and within D veinlets (Gustafson and Hunt, 1975) with quartz. Minor specularite and magnetite mineralisation occurs as dissemination and veinlets in all deposits. Mineralisation on the contacts between the andesite and feldspar-hornblende-quartz porphyry can reach high copper tenor in zones of biotite hornfels. Chalcopyrite is the dominant sulphide with minor pyrite and rare bornite, occurring in veinlets, blebs and disseminations. This style of mineralisation is often cross-cut by quartz-sulphide veining. Botija The Botija deposit is located in the northeast area of the Cobre Panam concession. Botija is hosted in several feldspar-quartz-hornblende porphyry dykes (up to four) which range in thickness from 20 m to 200 m, and which have intruded the granodiorite and andesite host rocks. In general, the dip of the more distinct dykes is approximately 70 to the north. Two irregular, keel shaped andesite roof pendants of approximately 500 m in diameter have been identified at Botija (Rose et al, 2012), separated by approximately 300 m and reaching depths of between 200 m to 300 m. A smaller pendant, up to 250 m along strike and extending to a depth of 150 m sits to the north of the deposit. ColinaThe Colina deposit is focused on a 3.0 km long by 1.2 km wide feldspar-quartz-hornblende porphyry sill and dyke complex (lopolith) that trends east-southeast. The majority of the feldspar-quartz-hornblende porphyry comprises of 50 m to 200 m thick sills that dip shallowly to the north and are often interconnected by dykes. Valle GrandeThe Valle Grande deposit is located to the southeast of Colina and is 3.2 km long and 1 km wide, striking northwest-southeast . The deposit is focussed on an irregular feldspar-quartz-hornblende porphyry lopolith. BalboaMineralisation at Balboa is dominantly hosted by a feldspar-quartz-hornblende porphyry that intrudes the adjacent andesite at a low to moderate angle, emanating from the north-northwest. Mineralisation is best developed in the central portion of the porphyry but weakens towards the contacts with the andesite. The porphyry can locally be described as a crowded feldspar porphyry, with variable percentages of feldspar and lesser quartz phenocrysts which range in size from 1 mm to 4 mm. MedioMedio is located immediately east-northeast of the Colina deposit and 2 km northwest of the Botija deposit. Drilling has delineated a 1.3 km by 800 m area of low to moderate grade porphyry mineralisation. Mineralisation is associated with silicified and sericitised porphyritic intrusive rocks and brecciated andesite volcanics. Copper tenor appears to be strongly correlated to vein and fracture intensity. Botija AbajoBotija-Abajo is approximately 2.5 km southeast of Botija. Drilling, completed mainly by PTC identified two deposit areas, Botija Abajo East and Botija Abajo West. Mineralisation is primarily located within feldspar-quartz-porphyry with some mineralisation extending into the andesitic tuffs. BrazoThe Brazo deposit is located approximately 3 km south-southeast of Botija. Copper and gold mineralisation was identified in a feldspar-quartz porphyry with dominant sericite alteration. The Brazo deposit has an approximate area of 600 m by 700 m and remains open to the east, northeast and at depth.

Mining at Cobre Panama involves ultraclass scaled mining equipment and conventional open pit methods at up to approximately 83 Mbcm of ore and waste mined per annum. The multiple pits will be mined in an optimized sequence and in phases, with ore crushed in-pit and conveyed overland to the nearby processing plant. Each of the Cobre Panam deposits is amenable to large scale, conventional open pit mining methods comprising of typical drill and blast, shovel and haulage truck techniques.At the end of 2020, four rope shovels, three ultraclass loaders and thirty ultraclass trucks were operating in the Botija Pit. The Botija pit will be mined first, followed by the Colina and Media pits. Mining in the Valle Grande and BABR pits will commence towards the end of mining of the Colina pit, with the Balboa pit being mined last. The crusher feed is expected to ramps up to 85 Mtpa in 2021 and ultimately to 100 Mtpa in 2023 at which rate it remains until 2041 before dropping to 75Mtpa between 2042 and 2054. The overall life of mine strip ratio (tonnes) is 1:1.Building upon the technologies developed at other FQM operations, the Project features in-pit crushing and conveying (IPCC). Blasted ore will be hauled to IPCC installations strategically located within the open pits. These installations will be near surface at the outset, but will be moved deeper into the pits as mining proceeds over time. In-pit conveyors will be extended to suit and these will converge on surface at a central transfer station discharging to a permanent overland conveyor connecting to the plant site.Trolley-assisted haulageTrolley-assisted haulage is a concept that is being adopted during the early life of operations. The primary truck haulage fleet is being delivered trolley-assist ready (TA). Additional pit ramp width has been included in the detailed pit phase designs to allow for the physical placement of transformers and catenary wire poles . In places, these ramps could be extended onto the waste dumps.Waste dumping The planned waste dumps (referred to as waste rock storage facilities, WRSF) are located surrounding the various pits, wherever space dictates, and in areas that have been largely sterilised by exploratory drilling. The dump profiles have been designed with a 32 batter angle, a 30 m batter height, 26 m width berms, and minimum 55 m wide ramps at 1:10 gradient. The overall angle of each ultimate dump slope is approximately 22.Drilling and blastingNear-surface saprolite material is being mined essentially as free-dig. As and when required, bench development that requires blasting will be blasted on bench heights of between 5 and 10 m and using small diameter blast holes.Below this horizon, production drilling and blasting will take-place in rock conditions requiring a range of drilling/charging patterns and powder factors. Due to the mix of large and medium sized rotary drills there will be large and medium diameter holes used to blast ore and waste.High and medium grade ore is preferentially direct fed to the crushers. However, some of this tonnage must be mined and stockpiled and hence, high and medium grade ore stockpiles are considered to be active throughout the mine life.Long term low grade ore and saprock ore stockpiles are developed over the life of the mine and are not reclaimed until the final years of operations.

Mining is open-pit, using a fleet of ultraclass electric shovels and ultraclass haul trucks. Four in-pit semi-mobile primary crushers feed two overland conveyors to the secondary crushers and main processing complex. The three 28 megawatt SAG mills and four 16.5 megawatt ball mills installed at Cobre Panama are the largest installed anywhere in the world, except for Sentinel. Cobre Panamas eighth mill came on line in mid-December 2019, providing additional capacity on the third milling train. A series of small debottleneck projects were commissioned during 2020, targeting to an annualized throughput of 85 million tonnes for 2021. Mill throughput for the month of December 2019 was 6.6 million tonnes and during December 2020 was 6.2 million tonnes. The Cobre Panama Technical Report released in March 2019 includes the plan for expansion of Cobre Panama from 85 Mtpa to 100 Mtpa starting in 2023. Description (Technical Report, March 2019) The initial four primary gyratory crushers located in the Botija Pit are semi-mobile in-pit installations. The primary crushing circuit will comprise up to five semi-mobile, independent, gyratory crushers (3 x ThyssenKrupp KB 63 x 89 and 2 x ThyssenKrupp KB 63 x 130) operating in open circuit. Each crusher will be positioned in-pit and remote from the plant area, and crushed ore will be transported to the plant by an overland conveyor. Crushed ore will be conveyed out of the pit to a surface transfer point, and thence by dual overland conveyors to where it will discharge into either secondary crusher feed bins or bypass direct via apron feeders to a coarse ore stockpile at the concentrator. Two trains of six apron feeders feeders and conveyors will draw ore from below the coarse ore stockpile and feed two parallel wet-grinding lines, each consisting of a 28 MW semi-autogenous grinding (SAG) mill and two 16.5 MW ball mills, all equipped with gearless drives. A third train of six apron feeders and conveyors will feed to a third SAG mill linked to the other train of ball mills to maximise their usage and enable maintenance of the treatment rate whilst also being able to operate independently. The SAG mill circuits will be closed by a combination of trommel screens followed by washing screens; conveyors will deliver screen oversize to pebble crushers via metal removal systems. A dedicated system for the recycling of reject balls is provided. The pebble crushing circuits will include pebble bins, up to four cone crushers, and a bypass arrangement. Crushed pebbles will return to the SAG mills via the stockpile feed conveyors. The pebble crushing plant is located adjacent to the secondary crushers. A parallel pebble handling circuit provides for standby and direct return of pebbles to stockpile, so as to support crusher and bin maintenance. Discharge from each SAG mill will be cycloned to recover the finished product whilst unfinished product will be evenly split between two ball-mill circuits. The four ball-mill circuits will be closed by hydrocyclones. The finished product from all cyclones will gravitate to two surge tanks, via in-stream particle and chemical samples, prior to pumping to the flotation area. Linked to the ball mill circuits will be two gravity gold recovery plants. A proportion of the ball mill discharge will be pumped to the two gravity gold circuits comprising scalping screens and centrifugal gravity concentrators. The centrifugal gravity concentrators will recover the free gold and direct it to a gold plant for upgrading to bullion. Tails from the gravity concentrators will be returned to the milling circuit.

Ore from the several open pits will be treated in a conventional process plant to produce a copper concentrate which will be pumped to the port, filtered and then loaded onto ships destined for world markets. Additionally, a molybdenum concentrate will be produced which will be filtered and bagged in the process plant before containerisation for export.The processing plant design is based upon a conventional sulphide ore flotation circuit to an initial nameplate throughput capacity of 85 Mtpa, expandable to 100 Mtpa capacity.Aside from in-pit primary crushing, the processing plant will include conventional facilities, such as:- crushing (secondary and pebble) and grinding (SAG/ball) to liberate minerals from the ore-froth flotation to separate most of the copper and molybdenum minerals from minerals of no commercial worth- differential flotation to separate the copper and molybdenum minerals from each other- storage of tailings and provision of reclaim water for the process- removal of water from the productsThe process plant is designed to process ore at a head grade of up to 0.65% Cu and 0.023% Mo. These levels are higher than the highest sustained head grades of 0.46% Cu and 88.40 ppm Mo scheduled to be mined in 2023 and 2029, respectively, but the design provides the flexibility to accommodate a wide range of head grades over the Project life.FlotationGround slurry will be directed to a flotation circuit where a bulk sulphide concentrate, containing copper, molybdenum, gold and silver values, will be collected and concentrated in a rougher followed by cleaner flotation. A primary high grade concentrate from the first rougher cell will be collected and cleaned directly in columns to produce a final product. The balance of concentrate from the remainder of the rougher cells will be collected, fed into three regrind mills, and then cleaned in two stages of mechanical cells followed by a one column stage to produce a final bulk concentrate. The rougher and cleaner circuits will be installed to meet ultimate capacity, with no further additions required. The bulk concentrate will be thickened in conventional thickeners (with no flocculant) and pumped to a differential flotation plant, where copper minerals will be depressed, and molybdenite floated into a molybdenum concentrate.Concentrates Copper/gold concentrate piped from the plant site will be filtered, reclaimed using a mechanical reclaimer and loaded by closed conveyors on to bulk ore carriers. The filtrate water will be treated at the port in a water treatment plant or aternatively pumped through a return pipeline to the TMF. The concentrate will be filtered in automatic filter presses and when dry (8% to 9% moisture), will be stored in a covered building with a capacity of 140,000 t. The molybdenum concentrate will be filtered, dried, and packaged in containers for shipment to offshore roasters. Tailings from the molybdenum flotation circuit will constitute the copper concentrate, which will be thickened/pumped/piped approximately 25 km to a filter plant at the Punta Rincn port site. If the molybdenum head grade is unsuitable, the molybdenum separation plant can be readily bypassed.Tailings disposal and process water reclaim For the first approximate fourteen years of the operation, tailings containing silicate, iron sulphide and other minerals from the rougher and cleaning steps will be deposited into the TMF located north of the mine and plant. The TMF is of centre line/downstream construction.The plant is equipped with preparation facilities for all required liquid and solid reagents, including frother, collector, promoter and lime. In addition, a ball charging system is provided in the milling area for feeding balls into the respective mills.

Reserves at December 31, 2020: Mineral Reserve: The actual cut-off grade for the estimate varies due to variable processing recovery, but otherwise reflects a longerterm consensus copper price of $3.00/lb, a molybdenum price of $13.50/lb, a gold price of $1,200/oz and a silver price of $16.00/oz.Mineral Resource: 0.15% Cu cut-off grade.