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rp-4 gold shaker table sale

The RP-4 shaker table is the most widely used and most successful gold gravity shaking concentrating table worldwide, used by small and large mining operations and the hobbyist. The patented RP-4 is designed for separation of heavy mineral and gemstone concentrate. The RP-4 table can process up to 600 (typically 400) lbs. per hour of black sand magnetite or pulverised rock with little to no losses. The RP-4 uses a unique reverse polarity of rare earth magnets, which will cause the magnetite to rise and be washed off into the tails. This allows the micron gold to be released from the magnetite, letting the gold travelling to the catch. The RP-4 is compact and weighs 60 lbs. With a small generator and water tank, no location is too remote for its use. The RP-4 is a complete, ready to go gold recovery machine. THERE ARE NO SCREEN INCLUDED with the small shaking table. Use was reservoirsgreater than 250 gallon and recycle all your water. Only 400 Watt of power drawn by typical pump. The small RP4 gold shaking has a mini deck of 13wide x 36 long = 3.25 square feet of tabling area. The RP-4 is the best and longest selling small miner shaker table still on the market today. With many 1000s of units sold during the last 10 years! Review the RP-4 Operating Manual and Installation Guide lower on this page.

The RP-4 uses a unique reverse polarity of rare earth magnets which will cause the magnetite to rise and be washed off into the tails and allowing the micron gold to be released from the magnetite leaving the gold travelling to the catch.

When assembling the RP-4, it is very important to set it up correctly to get the best recovery. The unit needs to be bolted preferably to a concrete pad or bedrock when in the field. It can be weighted down with seven or eight large sandbags. Wooden stands will set up harmonics and vibrations in the unit. Vibrations will create a negative effect on the concentrating action of the deck and create a scattering effect on the gold. We would strongly advise getting the optional stand to mount it. See a detailed RP4 Shaker Table review.

Once you have the RP-4 mounted or weighted down, you will want to level it, place a level under the machine on the bar running attached to the two mounting legs. Use washers to get a precise level adjustment. Once mounted and leveled, use the adjustment screw to adjust the horizontal slope of the deck. It took me about 10 minutes of playing with the adjustment till you are satisfied the slope angle was where it needed to be. A general rule for good recovery is less grade for the table deck and as much water as possible without scouring off the fine gold particles.

When the table is set, wet down your black sand concentrates with water and a couple drops of Jet-Dry to help keep any fine gold from floating off the table. You are now ready to start feeding the RP-4.

DO NOT dump material into the feed tray. You want a nice steady feed without overloading the table. Use a scoop and feed it steadily. Watch the back where the small gold should concentrate. If you see fine gold towards the middle, adjust your table angle just a bit at a time till it is where it needs to be.

Run a few buckets of black sand tailings that already panned out just in case there might have been some gold left behind. Its a good thing, too, because I pulled almost three pennyweights of gold out of my waste materials. Thats a pennyweight per bucket!

You could run all of you concentrates over this awesome little RP-4 Gravity Shaker Table. Some ran bottles No. 1 and No. 2 over the table a second time and cleaned it up some more, getting out almost all of the sand in No. 1 and removing more than half the sand from No. 2. It was amazing to see a nice line of fine gold just dancin down the table into the bottle. And, to think you were was about to throw away all of that black sand that still had color in it! This machine is small enough for the prospector and small-scale miner who, like me, wants all of the gold for his or her hard work. The 911MPE-RP-4 Gravity Shaker Table is also big enough to clean up bucket after bucket of concentrates from a big operation! The RP4 people came up with the solution for getting all of the gold!

All RP4 shaker tables operate best when firmly secured to a dense solid mounting base. Wooden stands will set up harmonics and vibrations. Dense concrete or solid bedrock is preferred or a heavy braced steel table sitting on concrete. Mount shaker table to solid bed rock if possible when operating in the field. When that is not an option, six or seven sand bags may also be used if concrete or bedrock is not available for mounting.

Place a level on top of the steel bar that extends between the two bolts down mounting feet.Use flat washers installed under either end of the mounting feet for precise level adjustment in the long axis.

At no time should sand or slime be re-circulated back with mill water. Large, calm, surface areas are required to settle slimes. Buckets, barrels or any deep containers with turbulent water will not allow slimes to settle. Tailings should discharge into a tails pond or into a primary holding vessel before entering slime settling ponds. Surface area is more important than depth. A small 10 x 20 ft. settling pond can be installed in about 30 minutes. Shovel a 6 high retainer wall of earth and remove all gravel. Lay a soft bed of sand in the bottom. A small raised wall area (with the top approximately 2 blow water level) should be placed around the pump area. Roll out plastic liner and fill with water. Desert areas require a plastic cover to retard evaporation. Use a 24 wood across pond and lay plastic.

As with ponds, at no time should sand or slime be re-circulated back with mill water. A calm surface is needed in the final two barrels to settle slimes. (In lieu of the last two barrels, the discharge from barrel two may be directed to a settling pond as outlined above.)Turbulent water will not allow slimes to settle. Tailings are discharged into the first container.

A small compact tailings thickener introduces tailings feed at a controlled velocity in a horizontal feed design that eliminates the conventional free settling zone. The feed particles quickly contact previously formed agglomerates. This action promotes further agglomeration and compacting of the solids. Slowly rotating rakes aid in compacting the solids and moving them along to the discharge pipe, these solids are eventually discharged at the bottom of the unit. Under flow from the thickener 60-65% solids are processed through a vacuum filter and a90-95% solids is sent to the tailings area. Tailings thickeners are compact and will replace ponds. A 23 ft. diameter will process flow rates at 800 gpm or 50 tph.

Pine oils and vegetation oils regularly coat the surface of placer gold. Sometimes up to 50% of the smaller gold will float to the surface and into the tails. The pine oil flotation method for floating gold is still in use today. A good wetting agent will aid in the settling and recovery of oil coated gold.

Separation of concentrate from tails Minerals or substances that differ in specific gravity of2.5 or to an appreciable extent, can be separated on shaker tables with substantially complete recovery. A difference in the shape of particles will aid concentration in some instances and losses in others. Generally speaking, flat particles rise to the surface of the feed material while in the presence of rounded particles of the same specific gravity. Particles of the same specific gravity but varying in particle size, can be separated to a certain extent, varying in particle size, can be separated to a certain extent, removing the larger from the smaller, such as washing slime from granular products.

Mill practice has found it advantageous in having the concentrate particles smaller than the tailing product. Small heavy magnetite particles will crowd out larger particles of flat gold making a good concentrate almost impossible with standard gravity concentrating devices. The RP-4 table, using rare earth reverse polarity magnets, overcame this problem by lifting the magnetite out and above the concentrate material thus allowing the magnetite to be washed into the tails. This leaves the non-magnetics in place to separate normally.

No established mathematical relationship exists for the determination of the smallest size of concentrate particle and the largest size of tailing particle that can be treated together. Other factors, such as character of feed material, shape of particles, difference in specific gravity, slope or grade of table dock and volume of cross flow wash water will alter the final concentrate.

Size of feed material will determine the table settings. Pulverized rod mill pulps for gravity recovery tables should not exceed 65-minus to 100-minus 95% except where specific gravity, size, and shape will allow good recovery. Recovery of precious metals can be made when processing slime size particles down to 500-minus, if the accompanying gangue is not so coarse as to require excessive wash water or excessive grade to remove the gangue, (pronounced gang), to the tails. Wetting agents must be used for settling small micron sized gold particles. Once settled, 400-minus to 500 minus gold particles are readily moved and saved by the RP-4shaker table head motion. Oversized feed material will require excess grade to remove the large sized gangue,thus forcing large pieces of gold further down slope and into the middling. Too much grade and the fine gold will lift off the deck and wash into the tailings. Close screening of the concentrate into several sizes requires less grade to remove the gangue and will produce a cleaner product. A more economical method is to screen the head ore to window screen size (16-minus) or smaller and re-run the middling and cons to recover the larger gold. This concept can be used on the RP-4 shaker tables and will recover all the gold with no extra screens. A general rule for good recovery is less grade for the table deck and as much was water as possible without scouring off the fine gold. Re-processing on two tables will yield a clean concentrate without excess screening. Oversized gold that will not pass through window screen size mounted on RP-4 shaker tables, will be saved in the nugget trap. Bending a small 1/4 screen lip at the discharge end of the screen will trap and save the large gold on the screen for hand removal.

On the first run, at least one inch or more of the black concentrate line should be split out and saved into the #2 concentrate bin. This concentrate will be re-run and the clean gold saved into the #1 concentrate pocket. Argentite silver will be gray to dull black in color and many times this product would be lost in the middling if too close of a split is made.

The riffled portion of the RP-4 shaker table separates coarse non-sized feed material better than the un-riffled cleaning portion. Upon entering the non-riffled cleaning plane, small gangue material will crowd out and force the larger pieces of gold further down slope into the middling. Screen or to classify.

The largest feed particles should not exceed 1/16 in size. It is recommended that a 16-minus or smaller screen be used before concentrating on the RP-4 shaker table, eliminating the need for separate screening devices. Perfect screen sizing of feed material is un-economical, almost impossible, and is not recommended below 65-minus.

A classified feed is recommended for maximum recovery, (dredge concentrates, jig concentrates, etc.) The weight of mill opinion is overwhelmingly in favor of classified feed material for close work. Dredge concentrates are rough classified and limiting the upper size of table feed by means of a submerged deck screen or amechanical classifier is all that is necessary. A separate screen for the sand underflow is used for improved recovery when using tables.

Head feed capacity on the RP-4 tables will differ depending on the feed size, pulp mixture and other conditions. Generally speaking, more head feed material may be processed when feeding unclassified, larger screened sized material and correspondingly, less material may be processed when feeding smaller sized classified rod or ball mill pulps. Smaller classified feed material will yield a cleaner concentrate. Ultimately, the shape of the feed material particles and a quick trial test will determine the maximum upper size.

The width between the riffles of the RP-4 table is small and any particle over 1/8 may cause clogging of the bedding material. A few placer operators will pass 1/8 or larger feed material across the RP-4 table, without a screen, with the intent of making a rough concentrate for final clean up at a later date. This method will work, but excess horizontal slope/grade of the table deck must not be used as some losses of the precious metals will occur. Magnetite black sands feed material, passing a 16-minus screen (window screen size if 16-minus + or -) will separate without losses and make a good concentrate at approximately 500 to 600lbs feed per hour for the RP-4. Head feed material must flow onto the RP-4 screen, at a constant even feed rate. An excess of head feed material placed onthe table and screen at a given time will cause some gold to discharge into the tailings nugget trap. Head feed material should be fed at the end of the water bar into the pre-treatment feed sluice. Do not allow dry head feed material to form thick solids. The wash water will not wash and dilate the head feed material properly, thus allowing fine gold to wash into the tails.

Feed material should disperse quickly and wash down slope at a steady rate, covering all the riffles at the head end,washing and spilling over into the tails trough. A mechanical or wet slurry pump feeder (75% water slurry) is recommended for providing a good steady flow of feed material. This will relieve the mill operator of a tedious chore of a constantly changing concentrate line when hand feeding.

Eight gallons of water per minute is considered minimum for black sands separation/concentration on the RP-4 shaker table. 15 gallons of water per minute is consideredoptimum and will change according to feed material size, feed volume and table grade. A 1 inch hose will pass up to 15 gpm, for good recovery, wash water must completely cover the feed material 1/4 or more on the screen.

The PVC water distribution bar is pre-drilled with individual water volume outlets, supplying a precision water flow. Water volume adjustment can be accomplished by installing a 1 mechanical PVC ball valve for restricting the flow of water to the water distributing holes. Said valve may be attached between the garden hose attachment and water distributing bar.

More water at the head end and less water at the concentrate end is the general rule for precise water flow. More feed material will occupy the head end of the RP-4 shaker table deck in deep troughs and less material will occupy the concentrate end on the cleaning plane. A normal water flow will completely cover the feed material over the entire table and flow with no water turbulence.

A rubber wave cloth is installed to create a water interface and to smooth out all water turbulence. This cloth is installed with holes. Holes allow water to run underneath and over the top of the cloth and upon exiting will create a water interface smoothing out all the water turbulence. Bottom of water cloth must contact the deck.

Avoid excessive slope and shallow turbulent water.For new installations, all horizontal grade/slope adjustments should be calculated measuring from the concentrate end of the steel frame to the mounting base. For fine gold, the deck should be adjusted almost flat.

All head feed must be fed as a 75% water pulp. Clean classified sand size magnetite will feed without too much problem when fed dry. Ground rod or ball mill feed material 65-minus or smaller must be fed wet, (75% water slurry by weight or more) and evenly at a constant rate, spilling over into the tails drain troughat the head end of the table. Feed material without sufficient water will not dilute quickly andwill carry concentrate too far down slope or into the tails. A good wet pulp with a deflocculant and a wetting agent will aid the precious metals to sink and trap within the first riffles, thus moving onto the cleaning plane for film sizing. Round particles of gold will sink instantly and trap within the first riffles. The smaller flat gold particles will be carried further down slope to be trapped in the mid riffles. Potential losses of gold can occur if the table deck is overloaded by force feeding at a faster rate than the smaller flat gold can settle out. Under-feeding will result in the magnetites inability to wash out of the riffles, thus leaving a small amount of magnetiteconcentrated with the gold. A small addition of clean quartz sand added to a black sand concentrate will force the magnetite to the surface and will aid in its removal. Slimes require a separate table operation.

In flotation, surface active substances which have the active constituent in the positive ion. Used to flocculate and to collect minerals that are not flocculated by the reagents, such as oleic acid or soaps, in which the surface active ingredient is the negative ion. Reagents used are chiefly the quaternary ammonium compounds, for example, cetyl trimethyl ammonium bromide.

A substance composed of extremely small particles, ranging from 0.2 micron to 0.005 micron, which when mixed with a liquid will not gravity separate or settle, but remain permanently suspended in solution.

A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different composition can be differentiated. Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel ortangent solid surfaces, and apply sufficient force to bring the surfaces together togenerate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other. The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil. Querns and mortars are types of these crushing devices.

A basic alkali material, such as sodium carbonate or sodium silicate, used as an electrolyte to disperse and separate non-metallic or metallic particles. Added to Slip to increase fluidity. Used to aid in the beneficiation of ores, to convert into individual very fine particles, creating a state of colloidal suspension in which the individual particles of gold will separate from clay or other particles. This condition being maintained by the attraction of the particles for the dispersing medium, water, purchase at any chemical house.

Manner in which the intensity and direction of an electrical or magnetic field change as a function of time that results from the superposition of two alternating fields, (+/-) that differ in direction and in phase.

The smelting of metallic ores for the recovery of precious metals, requiring a furnace heat. Each milligram of recovered precious metal is gravimetric weighed and reported as one ounce pershort ton. Atomic Absorption (AA finish) is the preferred method for replacing the gravimetric weighing system.

A reagent added to a dispersion of solids in a liquid to bring together the fine particles to form flocs and which thereby promotes settling, especially in clays and soils. For example, lime alters the soil pH and acts as a flocculent in clay soils. Acid reagents and brine are also used as a flocculent.

The method of mineral separation in which a froth created in water with air and by a variety of reagents floats some finely crushed minerals, whereas other minerals sink. Separate concentrates are made possible by the use of suitable depressors and activators.

An igneous oxide of iron, with a specific gravity of 5.2 and having an iron content of 65-70% or more. Limonite crystals, sometimes mistaken for magnetite, occurs with the magnetite and sometimes may contain gold. Vinegar will remove gold locked in limonite coated magnetite.

In materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces at the grain size level. See also CRUSHER for mechanisms producing larger particles. Since the grinding process needs generally a lot of energy, an original experimental way to measure the energy used locally during milling with different machines was proposed recently.

A typical type of fine grinder is the ball mill. A slightly inclined or horizontal rotating cylinder is partially filled with balls, usually stone or metal, which grinds material to the necessary fineness by friction and impact with the tumbling balls. Ball mills normally operate with an approximate ball charge of 30%. Ball mills are characterized by their smaller (comparatively) diameter and longer length, and often have a length 1.5 to 2.5 times the diameter. The feed is at one end of the cylinder and the discharge is at the other. Ball mills are commonly used in the manufacture of Portland cement and finer grinding stages of mineral processing. Industrial ball mills can be as large as 8.5 m (28 ft) in diameter with a 22 MW motor, drawing approximately 0.0011% of the total worlds power. However, small versions of ball mills can be found in laboratories where they are used for grinding sample material for quality assurance.

A rotating drum causes friction and attrition between steel rods and ore particles. But note that the term rod mill is also used as a synonym for a slitting mill, which makes rods of iron or other metal. Rod mills are less common than ball mills for grinding minerals.

Screening is the separation of solid materials of different sizes by causing one component to remain on a surface provided with apertures through which the other component passes. Screen size is determined by the number of openings per running inch. Wire size will affect size of openings. -500=500 openings per inch is maximum for gravity operations due to having a solid disperse phase.

Long established in concentration of sands or finely crushed ores by gravity. Plane, rhombohedra deck is mounted horizontally and can be sloped about its axis by a tilting screw. Deck is molded of ABS plastic, and has longitudinal riffles dying a discharge end to a smooth cleaning area. An eccentric is used to create a gentle forward motion, compounded to full speed and a rapid return motion of table longitudinally. This instant reverse motion moves the sands along, while they are exposed to the sweeping and scouring action of a film of water flowingdown slope into a launder trough and concentrates are moved along to be discharged at the opposite end of the deck.

A material of extremely fine particle size encountered in ore treatment, containing valuable ore in particles so fine, as to be carried in suspension by water. De-slime in hydrocyclones before concentrating for maximum recovery of precious metals.

A mixture of finely divided, micron/colloidal particles in a liquid. The particles are so small that they do not settle, but are kept in suspension by the motion of molecules of the liquid. Not amenable to gravity separation. (Bureau of Mines)

Flotation process practiced on a shaking table. Pulverized ore is de-slimed, conditioned with flotation reagents and fed to table as a slurry. Air is introduced into the water system and floatable particles become glom rules, held together by minute air bubbles and positive charged edge adhesion. Generated froth can be discharged into the tailings launder trough or concentrates.

The parts, or a part of any incoherent or fluid material separated as refuse, or separately treated as inferior in quality or value. The gangue or valueless refuse material resulting from the washing, concentration or treatment of pulverized head ore. Tailings from metalliferous mines will appear as sandy soil and will contain no large rock, not to be confused with dumps.

A substance that lowers the surface tension of water and thus enables it to mix more readily with head ore. Foreign substances, such as natural occurring pine oils, vegetation oils and mill grease prevent surface wetting and cause gold to float. Addition agents, such as detergents, (dawn), wetting out is a preliminary step in deflocculating for retarding gold losses.

RP4 shaker table for sale mini gold shaker table RP4 shaker table instructions RP4 shaker table dimensions RP4 gold shaker table RP 4 gravity shaker table utech RP4 shaker table RP 4 gravity shaker table price used RP4 shaker table for sale

Global mining solutions warrants that all mining equipment manufactured will be as specified and will be free from defects in material and workmanship for a period of one year for the RP-4. Providing that the buyer heeds the cautions listed herein and does not alter, modify or disassemble the product, gms liability under this warranty shall be limited to the repair or replacement upon return to gms if found to be defective at any time during the warranty. In no event shall the warranty extend later than the date specified in the warranty from the date of shipment of product by GMS. Repair or replacement, less freight, shall be made by gms at the factory in Prineville, Oregon, USA.

All bearings are sealed and no grease maintenance is required. Do not use paint thinners, or ketones to clean your deck. A small amount of grease should be applied to the adjustable handle which is used for the changing the slope of the deck.

Do not allow the RP-4 to stand in direct sunlight without water. Always keep covered and out of the sun when not in use. Heat may cause the deck to warp. Do not lift or pull on the abs plastic top, always lift using the steel frame. Do not attach anything to the abs plastic top. Do not attach PVC pipe to concentrate discharge tubes, constant vibration from the excess weight will cause stress failure of the plastic.

wills' mineral processing technology | sciencedirect

Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery has been the definitive reference for the mineral processing industry for over thirty years. This industry standard reference provides practicing engineers and students of mineral processing, metallurgy, and mining with practical information on all the common techniques used in modern processing installations. Each chapter is dedicated to a major processing procedurefrom underlying principles and technologies to the latest developments in strategies and equipment for processing increasingly complex refractory ores. The eighth edition of this classic reference enhances coverage of practical applications via the inclusion of new material focused on meeting the pressing demand for ever greater operational efficiency, while addressing the pivotal challenges of waste disposal and environmental remediation. Advances in automated mineralogy and analysis and high-pressure grinding rolls are given dedicated coverage. The new edition also contains more detailed discussions of comminution efficiency, classification, modeling, flocculation, reagents, liquid-solid separations, and beneficiation of phosphate, and industrial materials. Finally, the addition of new examples and solved problems further facilitates the books pedagogical role in the classroom.

Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery has been the definitive reference for the mineral processing industry for over thirty years. This industry standard reference provides practicing engineers and students of mineral processing, metallurgy, and mining with practical information on all the common techniques used in modern processing installations.

Each chapter is dedicated to a major processing procedurefrom underlying principles and technologies to the latest developments in strategies and equipment for processing increasingly complex refractory ores. The eighth edition of this classic reference enhances coverage of practical applications via the inclusion of new material focused on meeting the pressing demand for ever greater operational efficiency, while addressing the pivotal challenges of waste disposal and environmental remediation.

Advances in automated mineralogy and analysis and high-pressure grinding rolls are given dedicated coverage. The new edition also contains more detailed discussions of comminution efficiency, classification, modeling, flocculation, reagents, liquid-solid separations, and beneficiation of phosphate, and industrial materials. Finally, the addition of new examples and solved problems further facilitates the books pedagogical role in the classroom.

Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery has been the definitive reference for the mineral processing industry for over thirty years. This industry standard reference provides practicing engineers and students of mineral processing, metallurgy, and mining with practical information on all the common techniques used in modern processing installations. Each chapter is dedicated to a major processing procedurefrom underlying principles and technologies to the latest developments in strategies and equipment for processing increasingly complex refractory ores. The eighth edition of this classic reference enhances coverage of practical applications via the inclusion of new material focused on meeting the pressing demand for ever greater operational efficiency, while addressing the pivotal challenges of waste disposal and environmental remediation. Advances in automated mineralogy and analysis and high-pressure grinding rolls are given dedicated coverage. The new edition also contains more detailed discussions of comminution efficiency, classification, modeling, flocculation, reagents, liquid-solid separations, and beneficiation of phosphate, and industrial materials. Finally, the addition of new examples and solved problems further facilitates the books pedagogical role in the classroom.

Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery has been the definitive reference for the mineral processing industry for over thirty years. This industry standard reference provides practicing engineers and students of mineral processing, metallurgy, and mining with practical information on all the common techniques used in modern processing installations.

Each chapter is dedicated to a major processing procedurefrom underlying principles and technologies to the latest developments in strategies and equipment for processing increasingly complex refractory ores. The eighth edition of this classic reference enhances coverage of practical applications via the inclusion of new material focused on meeting the pressing demand for ever greater operational efficiency, while addressing the pivotal challenges of waste disposal and environmental remediation.

Advances in automated mineralogy and analysis and high-pressure grinding rolls are given dedicated coverage. The new edition also contains more detailed discussions of comminution efficiency, classification, modeling, flocculation, reagents, liquid-solid separations, and beneficiation of phosphate, and industrial materials. Finally, the addition of new examples and solved problems further facilitates the books pedagogical role in the classroom.

flotation: the past, present and future of mineral processing? | e & mj

As we look to the future, the mining industry faces a myriad of challenges. While demand for metals like copper, cobalt, lithium and iron ore is projected to reach record highs by 2050, ore grades are decreasing, orebodies are becoming more complex, and fewer tier 1 deposits are being discovered.

As metal prices increase, lower-grade orebodies are becoming economically feasible. But, with lower grades come higher tonnages to sustain production. Processing these deposits requires ever finer grinding for mineral liberation and significant flotation residence times. Lower grades mean that quantities of tailings and mine waste generated are also increasing. And, for many operations, their management is now a significant liability.

In many countries, water scarcity is a big constraint, and specific energy consumption and carbon emissions are rising as grades decrease; points that are at growing odds with mining companies efforts in improving their environmental, social and governance (ESG).

Given this backdrop, its pertinent to ask whether traditional beneficiation techniques like flotation, which have been a staple part of mineral processing circuits for more than 100 years and can, in some instances, be water, energy and time intensive, still serve the industrys needs?

Its not just flotation; mineral processing as a whole faces increased challenges, said Paolo Donnini, principal process engineer at SNC-Lavalin. We need to be smarter in how we go about extracting metals and minerals using less energy, smaller equipment, lesser footprints, less concrete everything really, he said.

Dr. Chris Anderson, specialist process engineer, and Marc Richter, AEM regional director for minerals processing at Hatch, agreed. Sustainable and effective changes in mining practices are essential to enable progress in value chain efficiencies, while recognizing the obligations to other important factors such as climate change, Richter said.

At a macro-level, efficiency in flotation can be driven using holistic engineering approaches. For example, Hatch offers two solutions Mine to Mill and Grade Engineering that aim to increase the overall efficiency of mineral processing operations, inclusive of flotation.

Richter explained: Mine to Mill is a consolidated approach focusing on optimizing mining operations across the value chain with a specific focus on mining (run-of-mine fragmentation), comminution and separation. Optimizing each stage in isolation can result in sub-optimal performance of the overall operation and reduce profitability. To get the best results, each stage is optimized considering the preceding and subsequent stages.

This approach increases plant throughput, reduces energy consumption and operating costs, and improves process efficiency. It can be applied to greenfield projects or business improvement initiatives on existing assets. Typical projects see noticeable throughput benefits with a short payback time.

In December 2020, Hatch announced it would commercialize Grade Engineering, an integrated and methodical approach for assessing the viability and implementation of coarse separation options in preconcentration.

Grade Engineering is designed to reject low-value material early in the extraction value chain to provide high-quality feed, Richter said. By reducing uneconomical material early in the process and improving the quality of the processed ore, Grade Engineering improves overall metal production and reduces water and energy intensities, while minimizing wet tailings.

Anderson added: Through Grade Engineering, we have worked with several clients to develop coarse particle flotation (CPF) circuits aimed at reducing energy consumption in comminution, while ensuring liberation of the valuable metals in the deposit. These projects included evaluating options for the recovery of coarse valuable-bearing composites in the primary grinding circuit and early gangue rejection; and recovery of coarse value-bearing composites lost to conventional flotation tailings.

In the right applications, CPF can offer a reduction in energy demand in preceding comminution stages, increased production rates, and result in coarser tailings streams, which are easier to handle and more geotechnically stable.

The limitations of conventional flotation cells can be overcome through the use of fluidized-bed flotation machines, like Eriezs HydroFloat, which are specifically engineered for the selective recovery of feeds containing very coarse particles. However, the coarsest particle size that can be floated will depend on the liberation of the valuable mineral.

Were also currently implementing a project in North America to install Woodgrove Staged Flotation Reactors (SFR) in a cleaner-scalper application, and several projects looking at Eriez StackCells as a retrofit to either a pre-rougher or rougher application where the client is seeking additional residence time in a constrained footprint, Anderson said.

Conventional flotation cells are known to be relatively inefficient in terms of promoting particle-bubble contacting. However, the historical approach is to compensate by adding a scale-up factor to the residence time obtained through bench-scale tests. This approach is increasingly limited in circuits, which are fine grained, requiring long residence times and complex cleaning circuits to achieve the necessary grade.

Technologies such as the Jameson cell and column cell have been substantially improved over the past 20 to 30 years and are increasingly viewed as mature technologies. The Jameson cell in particular can be used to develop compact full-plant solutions, which offer some attractive advantages. Newer technologies such as the Woodgrove SFR and Direct Flotation Reactor (DFR) cell are also gaining interest in large-scale installations.

The Eriez HydroFloat cell is seeing significant interest in coarse particle rejection applications in copper and PGMs (more on this later). If successful, CPF may eventually become a standard in flotation applications where gangue can be liberated at coarse sizes (~500 microns). Other technologies such as the NovaCell are also gaining traction in this space.

Anderson explained: Our role is to help the client through the process development and bring newer technologies into consideration as early as possible, particularly in the conceptual and prefeasibility phases.

Columns and Jameson cells can be simulated using traditional batch flotation tests and HydroFloat performance can be inferred based on mineralogy and liberation information. Ultimately, pilot-scale test work must be performed. However, the information derived from early mineralogy and bench-scale tests can be used for trade-off studies to focus in on high-value alternatives.

I think low-footprint technologies such as Jameson cells and Woodgrove cells may prove disruptive as they allow substantial throughputs with a low footprint. In the long term, these technologies may find applications closer to the mining face, especially for underground applications.

Like Richter and Anderson, Donnini has noticed a growing interest in novel flotation technologies over the past five years and, more importantly, a willingness from mining companies to consider their applicability and economic feasibility.

Were starting to dissect flotation, he said. Rather than trying to create huge cells of 500 cubic meters (m3) or more, vendors like Woodgrove and Eriez are trying to get greater efficiencies from smaller cells. And theyre doing that by looking at the fundamentals of flotation. For example, Woodgroves SFR splits the flotation process into three stages contacting, separation, and then removal of the froth and tails. Rather than looking at flotation as a macro process, its being looked at more closely as a micro process.

Likewise, classically in flotation, we try to embrace the whole particle size distribution of the feed material. But with technologies like Eriezs HydroFloat, theyre suggesting that we narrow the particle-size distribution to create more efficiency. Its a much more elegant, accurate and precise approach to the process.

With CPF, you dont have to grind the ore to the fine endpoint thats required for conventional flotation technology, he explained. You can separate ore from gangue at a size that is roughly twice the size of conventional technology. Which means you dont have to over grind and you dont have to waste any energy, which is very expensive. Also, mines dont have to worry about storing tailings that are very fine and unstable the material can be easily dewatered and you can reduce conventional flotation capacity as well.

It depends upon the ore and its density but, for copper, which were really focusing on, you get an acceptable recovery in conventional flotation up to about 120 or 130 microns. Certainly, it drops off before 200 microns.

With CPF, you can usually take that up to 400 microns, which reduces the amount of grinding needed by half. In grinding, the amount of energy required increases disproportionately as the material becomes finer the finer the material being ground, the more energy is required which is why ultra-fine grinding mills use a lot of energy.

According to a new report from Weir Group, Mining Energy Consumption 2021, comminution accounts for 25% of final energy consumption at the average mine site. Across the hard-rock mining sector, this equates to around 1% of total global energy consumption every year. The report author, Marc Allen, stated that a 5% incremental improvement in energy efficiency across comminution could result in GHG emission reductions of more than 30 million metric tons (mt) of CO2e. To put that into perspective, New Zealands total emissions stand at around 35 million mt of CO2e.

CPF is not a new concept. However, what is new is its application at a commercial scale in base metals. Eriez has been applying CPF in phosphate and potash for 20 years and, in the past eight years, has been working to bring the benefits into base metals operations, particularly copper.

We did a lot of pilot work at Rio Tinto Kennecott Utah Copper in the U.S., Wasmund said. And we discovered that CPF really suits tails scavenging. When we started looking at the tails of conventional plants, we realized the material being lost to tails wasnt spread across the entire size distribution. It was actually very low in the size distribution where conventional flotation is effective, which makes sense.

Where we see a big drop-off is where the material is too coarse, or where its too fine. And we found that its very easy to develop a business case for reprocessing tails from a conventional plant using the HydroFloat. You can make money just by reprocessing and treating the material that conventional flotation isnt good at recovering.

Conventional flotation is not efficient for coarse particles, explained Wasmund. But what if we put [these new flotation technologies] right into the mill circuit and remove a coarse product before we overgrind it? Then youd get all the benefits of having a coarse tail, a reduction in energy requirements, and you can reduce the size of your plant. Thats what were calling coarse gangue rejection and its being worked on by a number of mining companies right now.

Its an ore sorting technology, except it sorts material at maybe half a millimeter, as opposed to conventional sensor-based ore sorting, which decides whether a 6-in. rock can be differentiated and disposed of before it goes through the plant, Wasmund explained.

This is ore sorting on a much finer scale, and the benefit is that it produces a much higher recovery rate. Sensor-based ore sorting uses blasts of air to shoot rocks containing a certain percentage of gangue off of a conveyor belt. The cut-off grade means that a certain amount of ore is lost along the way. Whereas in coarse gangue rejection, because the material is much finer, the margin of recovery is that much higher.

Anglo American is trialing the use of coarse particle recovery or rejection at Mogalakwena in South Africa as part of its FutureSmart Mining program. The company is also using it in tails scavenging applications at mines like Quellaveco in Peru and El Soldado in Chile, and to generate coarse tails that can be co-deposited with fine material in a dry facility, without a water impoundment.

In a previous interview (Copper processing: the quest for efficiency at scale, December 2020), a spokesperson for Anglo said CPF is a key technology in closing the loop on its water usage too an initial step toward the companys goal of dry processing.

We did a study with Capstone Mining based on their Cozamin site using coarse gangue rejection. And found that we could reduce the ball mill requirement by 30%-50%, convert 30% of the tails to a coarse size (instead of 200 microns, they were 600 microns) and reduce the amount of conventional flotation by 40%, said Wasmund, proudly. All of these benefits are site specific. But CPF, as a tool, can be used in so many different ways. There could be exciting applications that we dont even know about yet!

Another concept that Eriez and others like Woodgrove are working on is staged flotation. Again, the technology is not new Eriez has been running its StackCell in coal applications for 15 years but the company has recently redesigned it to handle base metals.

People have known about this for a long time, but still prefer to do everything in a single stirred tank, Wasmund said. If you break the flotation process down into two steps, as with the StackCell, then you can reduce the amount of working volume needed by a factor of four to five. Thats been validated at a number of sites.

The StackCell, which is much smaller than a traditional flotation cell, can shrink the size of a flotation plant by 50%. The knock-on effect is that it also requires less concrete (smaller carbon footprint), less piping to connect the units, and fewer electrical connections and cable trays and pipe racks, thus reducing CAPEX and engineering times too. This makes it ideal for use in plant expansions or at projects where a minimal footprint is important.

In metal mines, orebody characteristics can vary significantly throughout the life of mine. Initial and ongoing test work are crucial to optimizing the reagents used in flotation circuits. Donnini believes there is much to be learned from the industrial minerals market in this regard.

We just finished an expansion study for an open-pit mine, he explained. Theyre looking at the material theyre going to be mining for the next 10 years, and its very different to what they have been mining for the past 15.

The challenge that creates in flotation is that a lot of factors can interfere with the surface chemistry; Ive known of flotation plants that were upset for weeks due to something that was present in the parts-per-million range. Its a continuously changing environment, and often chemicals are an afterthought.

If we look at the work that Chinese phosphate manufacturers have done to develop reagent packages that are optimized for low-grade minerals they are developing the reagent package and then developing the flotation train based around that. The Phosphate Institute in Florida, which is largely supported by Mosaic, has done lots of work on this too.

I think one of the approaches that is necessary in the future is to identify the reagent package and how we want to use it in the process, and then build the flotation circuit around that package. Im sure others will say they do that already, but were not taking full advantage of the opportunity because most mines are using standard reagents.

I understand its expensive to do investigations and to invest in customized reagents. But at the same time, because of the challenges that are coming our way and theyre not coming, they are here already it makes total sense.

Dr. Kevin Brooks, APC global lead at Hatch, has pioneered the use of model predictive control (MPC) on flotation plants worldwide. Work with Anglo Platinum, FQML and Glencore has demonstrated that the combination of linear models derived from plant testing, and feedback from machine vision applications and/or online grade measurements yields significant benefits in grade, recovery and reagent usage.

Brooks explained: MPC is a technology developed in the oil refining industry more than 30 years ago. Its uptake in the minerals industry has been slow but has accelerated over the last five to 10 years. The technology slots right into the current thinking around Industry 4.0 and machine learning. The ability to optimize a unit in real-time yields paybacks in order of months leads to more consistent operation across shifts and allows plant operators to concentrate on the more manual areas of the unit.

Comminution is also an area where MPC yield benefits. Brooks sees a time when milling and flotation MPCs will be combined using a coordination model. This is the route to online control and optimization embracing the mine to mill concept, he said. Work is already being done to combine scheduling models with MPC to provide this wide scope of optimization and its associated benefits.

Donnini believes that, going forward, a more proactive approach is needed, one that encompasses prediction and automatic adjustment of plant parameters. Advanced process control and statistical process control will allow us to do a much better job of controlling the flotation process than we do today, he said.

In an operating environment, for a model to be useful, it must be able to accurately predict a reactive model is no use, Donnini said. That is a key element of the Industry 4.0 concept; mines need to be able to simulate their processes accurately enough so that they can predict whats going to happen in their processes, based on whats coming in.

Donnini believes advanced process control and neural networks offer a timely solution to predicting flotation performance today. The mathematical algorithms learn how a process operates and, using a certain number of inputs, take corrective action based upon experience.

To me, that is the solution to advanced process control in flotation, he said. I struggle to imagine somebody developing a model, being willing to spend the amount of money that it would take to collect all the data on factors that are likely to affect a flotation process. The alternative is that we learn (the machine learns). The more that machine is exposed to certain events, then the more accurately it can predict conditions.

Companies like Metso Outotec and FLSmidth have technologies that watch and measure froth properties, but I dont think anyone has closed the loop yet to allow those systems to initiate corrective action. Thats still left to the operator to do. But that will be an important step forward in controlling the flotation process.

Another important aspect, one that will be crucial to achieving all of the above, is continuous feed monitoring and particle size analysis. Today, this tends to be done in batches and the tests can take hours to return results. To install a laser scanner over a conveyor would provide a partial solution. However, the accuracy depends heavily on how a particle presents to the laser at a specific point in time.

Most particles are not spherical, but most models are created based on the assumption of spherical particles Again, in time, accurate, real time particle size analysis will improve our modelling capabilities as well.

What this article has shown is that flotation, as a technology, is not going anywhere. In fact, rather than being a limiting aspect of future flowsheets, one that could potentially be phased out over time, its going in quite the opposite direction.

Novel flotation technologies applied in new ways throughout flowsheets will prove invaluable in enabling ESG-conscious mining companies to meet future market demands while minding their resource consumption.

Anderson and Richter agreed. Flotation will remain a necessary portion of the flowsheet for the foreseeable future as a means of concentrating prior to roasting and leaching or even smelting, Anderson said. Dry technologies such as gravity, magnetic separation and electrostatic separation are unable to exploit the differences in surface characteristics which is a key separation method in mineral processing. However, its application may move closer to the mining face as time goes on.

Wasmund was pragmatic. Its important to put flotation into perspective with other extraction processes, he said. Its actually a very green technology, because it allows mines to separate valuable material from waste right after mining. If you compare that to other technologies

For instance, theres a big debate in the nickel market about where nickels going to come from for future electric vehicles. There are two main types of nickel resources: sulphides and laterites (oxides). Flotation can be used to concentrate sulphide nickels up to 30%, whereas laterites cannot be preconcentrated. The whole feed must be treated through high-pressure acid leaching (HPAL) or an electric arc furnace. And that increases the cost of production significantly, as well as the environmental footprint.

When were all driving electric vehicles and charging our cars at home with massive copper wires that connect up to our houses to get that copper and nickel were going to have to mine deposits that are much lower grade than those mined today. And the best way to do that is using more efficient forms of flotation.

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what are the differences between ball mill and rod mill? | fote machinery

Ball mill and rod mill are the common grinding equipment applied in the grinding process. They are similar in appearance and both of them are horizontal cylindrical structures. Their cylinders are equipped with grinding medium, feeder, gears, and transmission device.

The working principle of ball mill and rod mill machine is similar, too. That is, the cylinder drives the movement of the grinding medium (lifting the grinding medium to a certain height then dropping). Under the action of centrifugal force and friction, the material is impacted and ground to required size, so as to realize the operation of mineral grinding.

Grate discharge ball mill can discharge material through sieve plate, with the advantage of the low height of the discharge port which can make the material pass quickly so tha t to avoid over-grinding of material. Under the same condition, it has a higher capacity and can save more energy than other types of mills;

It is better to choose a grate discharge ball mill when the required discharge size is in the range of 0.2 to 0.3 mm. Grate discharge ball mill is usually applied in the first grinding system because it can discharge the qualified product immediately.

Overflow discharge ball mill can grind ores into the size under 0.2 mm, so it is very suitable for the second grinding system. The capacity of it is about 15% lower than grate discharge ball mill in the same specification, and the loaded grinding medium is also less than that one.

It can be divided into three types of rod mills according to the discharge methods, center and side discharge rod mill, end and side discharge rod mill and shaft neck overflow discharge rod mill.

It is fed through the shaft necks in the two ends of rod mill, and discharges ore pulp through the port in the center of the cylinder. Center and side discharge rod mill can grind ores coarsely because of its structure.

This kind of rod mill can be used for wet grinding and dry grinding. "A rod mill is recommended if we want to properly grind large grains, because the ball mill will not attack them as well as rod mills will."

It is fed through one end of the shaft neck, and with the help of several circular holes, the ore pulp is discharged to the next ring groove. The rod mill is mainly used for dry and wet grinding processes that require the production of medium-sized products.

The diameter of the shaft neck is larger than the diameter of the feeding port about 10 to 20 centimeters, so that the height difference can form a gradient for ore pulp flow. There is equipped with a spiral screen in the discharge shaft neck to remove the impurities.

It has high toughness, good manufacturability and low price. The surface layer of high manganese steel will harden rapidly under the action of great impact or contact. The harder index is five to seven times higher than other materials, and the wear resistance is greatly improved.

It has high toughness, good manufacturability and low price. The surface layer of high manganese steel will harden rapidly under the action of great impact or contact. The harder index is five to seven times higher than other materials, and the wear resistance is greatly improved.

It is made of several elements such as chromium and molybdenum, which has high hardness and good toughness. Under the same work condition, the service of this kind of ball is one time longer than the high manganese steel ball.

After the professional technology straightening and quenching processing process, a high carbon steel rod has high hardness, excellent performance, good wear resistance and outstanding quality.

The steel ball of ball mill and the mineral material are in point contact, so the finished product has a high degree of fineness, but it is also prone to over-grinding. Therefore, it is suitable for the production with high material fineness and is not suitable for the gravity beneficiation of metal ores.

The steel rod and the material are in line or surface contact, and most of the coarse particles are first crushed and then ground. Therefore, the finished product is uniform in quality, excellent in particle size, and high in qualification rate.

The cylinder shape of the rod mill and the ball mill is different: the cylinder of the rod mill is a long type, and the floor area is large. The ratio of the length to the diameter of the cylinder is generally 1.5 to 2.0;

The cylinder of the ball mill is a barrel or a cone. And the ratio of the length to the diameter of the cylinder is small, and in most cases the ratio is only slightly larger than 1, and the floor area is small, too.

The above is the main content of this article. The ball mill and the rod mill are the same type of machine on the appearance, but there are still great differences in the interior. It is very necessary to select a suitable machine for the production to optimize the product effect and maximize its efficiency.

As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.

Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.

grinding cylpebs

Our automatic production line for the grinding cylpebs is the unique. With stable quality, high production efficiency, high hardness, wear-resistant, the volumetric hardness of the grinding cylpebs is between 60-63HRC,the breakage is less than 0.5%. The organization of the grinding cylpebs is compact, the hardness is constant from the inner to the surface. Now has extensively used in the cement industry, the wear rate is about 30g-60g per Ton cement.

Grinding Cylpebs are made from low-alloy chilled cast iron. The molten metal leaves the furnace at approximately 1500 C and is transferred to a continuous casting machine where the selected size Cylpebs are created; by changing the moulds the full range of cylindrical media can be manufactured via one simple process. The Cylpebs are demoulded while still red hot and placed in a cooling section for several hours to relieve internal stress. Solidification takes place in seconds and is formed from the external surface inward to the centre of the media. It has been claimed that this manufacturing process contributes to the cost effectiveness of the media, by being more efficient and requiring less energy than the conventional forging method.

Because of their cylindrical geometry, Cylpebs have greater surface area and higher bulk density compared with balls of similar mass and size. Cylpebs of equal diameter and length have 14.5% greater surface area than balls of the same mass, and 9% higher bulk density than steel balls, or 12% higher than cast balls. As a result, for a given charge volume, about 25% more grinding media surface area is available for size reduction when charged with Cylpebs, but the mill would also draw more power.

ultrafine grinding - an overview | sciencedirect topics

UFG of pyrite concentrates for subsequent leaching is used in ores, where refractoriness to direct cyanidation arises from fine to ultrafine (<20, >0.02m) gold mineral inclusions in the pyrite and/or arsenopyrite. By grinding to 80% passing 10mm a significant fraction of the colloidal size (<0.5m) gold is also being exposed and rendered amenable to cyanidation. On the downside, the huge increase in surface area of pyrite that is created by UFG magnifies 10-fold any preg-borrowing effects, probably assisted by free cyanide, consumption by adsorption onto pyrite surfaces and the formation of thiocyanate (SCN). If there is carbonaceous matter in the UFG concentrate to be leached, it can contribute to significant losses, because of its relatively huge surface and the irreversible sorption of gold (preg-robbing). More details on this technique may be found in Chapter 17.

Ultrafine grinding (UFG) has continued to evolve in terms of equipment development. A number of specialist machines are commercially available including Xstrata's IsaMill, Metso's Vertimill, Outotec's High Intensity Grinding (HIG) mill, and the Metprotech mill. UFG equipment has been developed with installed powers of up to 5MW.

Compared with conventional ball or pebble milling, the specialist machines are significantly more energy efficient and can economically grind to 10m or lower, whereas the economical limit on conventional regrind mills was generally considered to be around 30m. Coupled with improvements in downstream flotation and oxidation processes, the rise of UFG has enabled treatment of more finely grained refractory ores due to a higher degree of liberation in the case of flotation or enhanced oxidation due to the generation of higher surface areas.

In 1993, the Salsigne Gold Mine was reopened. Salsigne treated a gold-bearing pyrite/arsenopyrite ore by flotation, with the flotation tails treated in a CIL circuit and the concentrate reground in a conventional mill to approximately 2530m. The oxygen demand for reground concentrate was high and the rate of oxidation was slow. The concentrate was initially oxidized for approximately 6h using oxygen injection via a Filblast aerator before cyanidation. Additional oxygen was added in in the second CIL stage and hydrogen peroxide was added into the fourth unit to maintain dissolved oxygen concentrations of >10ppm.

Goldcorp have commenced operations at the Elenore Gold Project in Quebec, Canada. The mineralogy of the ore and hence the circuit selection show similarities to those at Salsigne. The main sulfides are arsenopyrite, pyrite, and pyrhottite. The ore is floated, with the flotation tails passing to a tails CIL circuit and the flotation concentrate reground before passing to the concentrate CIL circuit via preaeration tanks designed to achieve 18-h contact with oxygen. The main difference between the Salsigne and Elenore projects is that the Elenore concentrate is ground to 10m and oxidation of the sulfides is substantially complete before cyanidation.

Ultrafine grinding is used to liberate gold finely disseminated in metallic sulfides. KCGM is the first gold mine using ultrafine grinding followed by cyanidation (Ellis and Gao, 2002). The gold sulfide concentrate is grind with an IsaMill to a P80 of 1012m. In the first 3years of operation, high consumption of cyanide and high gold content in leach residues were experienced with difficulty overcoming these issues (Deschnes etal., 2005).

Eleonore Mine is the first commercial application of the IsaMill in Canada (Deschnes and Fulton, 2013). Ultrafine grinding is applied to liberate gold finally disseminated in sulfide minerals. The pyrrhotite concentrate produced by flotation was used to determine the leaching strategy at the laboratory scale. The concentrate grind at a P80 of 10m contained 65% gangue minerals, 23% pyrrhotite, 2.2% pyrite, 9.6% arsenopyrite, 75.5g/t Au, and 5.0g/t Ag. Gold was present as native gold and electrum. A test conducted at 2000ppm NaCN and pH 11.0 produced 97.0% extraction of gold in 72h. It was found that an efficient leaching required only 35ppm DO. However, the presence of reactive pyrrhotite resulted in a cyanide consumption of 31.5kg/t NaCN.

Three key features were identified to optimize the process: the use of a pretreatment, the addition of oxygen and the addition of lead nitrate. A 16-h duration was the optimum retention time for the pretreatment (Figure26.15). In the conditions below, the lowest consumption of cyanide (6.0kg/t NaCN) was associated with a high extraction of gold (97.5% Au; leach residue at 1.92g/t Au). The 8-h pretreatment did not passivate the sulfides as much as the 16-h one and the cyanide consumption increased to 6.6kg/t while the gold extraction slightly decreased to 96.9% (leach residue at 2.36g/t Au). A 24-h pretreatment decreased the gold extraction and increased the cyanide consumption.

Figure26.15. Effect of duration of pretreatment on gold extraction from the Eleonore flotation concentrates. Pretreatment: 0.25L/min/kg oxygen, pH 11.0; cyanidation: 2000ppm NaCN, pH 11.0, DO 35ppm, 20C, 35% pulp density (Deschnes and Fulton, 2013).

For the addition of oxygen in the pretreatment, it was found that increasing the flow rate of oxygen addition from 0.13L/min/kg to 0.25L/min/kg reduced the cyanide consumption from 6.4kg/t to 6.0kg/t (Figure26.16), as well as the gold content of the leach residue from 2.52 to 1.92g/t Au. When the oxygen addition was increased to 0.53L/min, the gold content of the leach residue increased to 2.46, while the cyanide consumption went to 5.5kg/t NaCN (Figure26.16).

Figure26.16. Effect of oxygen flow in the pretreatment on gold extraction from the Eleonore flotation concentrate. Pretreatment: 2.00kg/t lead nitrate, pH11.0, 16h; cyanidation: 2000ppm NaCN, pH 11.0, DO 35ppm, 20C, 35% pulp density (Deschnes and Fulton, 2013).

It was found that increasing the lead nitrate addition from 1.0kg/t to 6.0kg/t in the pretreatment resulted in a decrease in the consumption of cyanide from 7.2kg/t to 1.2kg/t (Figure26.17). At 6kg/t lead nitrate, the pyrrhotite passivation reached a point where the oxygen consumed by the concentrate was significantly reduced. While the DO was usually below 0.5ppm during the entire pretreatment, at 6kg/t lead nitrate, the DO increased beyond 4ppm after 2h. According to the trend, the gold extraction obtained with 23kg/t lead nitrate appears not to be biased and would probably have to be in the range of 2.2g/t Au. At dosages above 4kg/t lead nitrate, the gold content of the leach residue was observed to slightly increase; considering the 0.1g/t variation in fire assay. The gold extraction is not overly sensitive to lead nitrate beyond 2kg/t addition.

Figure26.17. Effect of lead nitrate in the pretreatment on gold extraction from the Eleonore flotation concentrate. Pretreatment: 0.25L/min/kg oxygen, pH 11.0, 16h; cyanidation: 2000ppm NaCN, pH 11.0, DO 35ppm, 20C, 35% pulp density (Deschnes and Fulton, 2013).

With the right conditions, free cyanide concentration in leaching can be significantly reduced, as shown in Figure26.18. A reduction of free cyanide from 2000ppm to 800ppm NaCN had a minor effect on the gold content of the leach residue (which varied by 0.2g/t). For this series, the gold extraction showed an average of 97.0%. A 6.8% decrease in gold extraction occurred when the cyanide concentration was reduced to 550ppm (gold extraction of 92.2%). This is expressed by a sharp increase of the gold content of the leach residue. The cyanide consumption was 1.2kg/t NaCN for the experiment, using a dosage of 800ppm NaCN.

Figure26.18. Effect of cyanide concentration on gold extraction from the Eleonore flotation concentrate. Pretreatment: 0.25L/min/kg oxygen, pH 11.0, 16h, 5.5kg/t lead nitrate; cyanidation: 0.5kg/t lead nitrate, pH 11.0, DO 35ppm, 20C, 35% pulp density (Deschnes and Fulton, 2013).

It is critical to be aware that lead nitrate plays a major role in the composition of the solution that will be processed for cyanide destruction. Figure26.19 shows the variation of solution composition in terms of thiocyanate, iron, copper, and cyanate concentrations as a function of lead nitrate added. The main contributor to cyanide consumption is the formation of thiocyanate, which decreased from 2877 to 843mg/L. The iron concentration also decreased significantly (from 156 to 27mg/L). Because the iron cyanide is a very strong complex, this becomes an issue when its concentration is too high in the barren solution. Difficulties will be encountered in striving to meet the criteria for total cyanide after destruction. The dispersion of thiocyanate concentration indicates some variation in the surface conditions of pyrrhotite prior to cyanidation. In this example, about 50% of the cyanide was unaccounted for. The unaccounted cyanide consumed is probably related to the precipitation of iron cyanide hydroxide species.

Figure26.19. Variation of CNS, Fe, Cu, and CNO concentrations as a function of lead nitrate addition during cyanidation of Eleonore flotation concentrate. Pretreatment: 0.25L/min/kg oxygen, pH 11.0, 16h; cyanidation: 2000ppm NaCN, pH 11.0, DO 35ppm, 20C, 35% pulp density (Deschnes and Fulton, 2013).

Optimization of the plant by the project owner continues after plant commissioning with the aim of maximizing plant throughput within the limitations of ore supply and the maximum capacity of the high capital cost unit processes. This is typically the comminution circuit or downstream concentrate treatment process (e.g.,POX or bio-oxidation plant) for refractory gold ores. Recovery and operating costs are other targets for optimization.

The Macraes Gold Project has treated sulfide ore, oxide ore (in campaigns) and retreated some tailings. The expansion in the throughput of the Macraes Gold Project since plant commissioning in 1990 is illustrated in Figure11.3. The periodic high treatment rates for oxide ore represent periods when the main grinding circuit was used to process oxide ore, during 1991, just prior to plant upgrade in 1999, and twice to process stockpiled oxide ore, in 2001 and 2003. The low rate of continuous treatment of oxide ore through a new mill can be seen post May2003.

In late 1994, the plant was expanded by the addition of flotation and fine grinding capacity. The primary grind size was increased and ultra-fine grinding of flotation concentrate installed to improve gold recovery from flotation concentrate in the subsequent CIL circuit.

In late 1999, a further expansion of the plant was undertaken with the addition of a ball mill (ML350) to reduce the primary grind size and allow a further increase in throughput. In addition, a POX plant was installed to improve refractory gold recovery through oxidation of the flotation concentrate.

In late 2001, a retreatment flotation circuit was installed to recover gold from old sulfide tailings and in mid-2003, a further single-stage SAG mill was installed to allow for the parallel treatment of oxide ore or additional sulfideore.

Each plant expansion was followed by a steady increase in plant throughput. The only element of the plant that became redundant over this period was the ultra-fine regrind facility that was shut down in 1995 due to higher-than-expected operating costs.

The term refractory ore is used to classify different gold ores that are not amenable to the traditional cyanidation processes. Gold in refractory sulfide ores occurs as fine inclusions or in solid solution typically within pyrite, marcasite, and arsenopyrite grains. In this type of ore, because the gold is encapsulated, the interaction with cyanide to form the soluble metal complex is inhibited (Marsden and House, 2006; La Brooy etal., 1994).

Grinding has been used to enhance gold liberation from the host sulfide-containing mineral or for particle-size optimization before oxidative pretreatments; however, when gold is encapsulated in a sulfide matrix, conventional grinding (P80=75m) without a pretreatment usually does not result in improved gold recoveries in the leaching process. Ultra-fine grinding (P8010m) has been proposed as an alternative to unlock gold from sulfidic refractory ores; however, the cost of size reduction to this level makes it applicable only for concentrates (Corrans and Angove, 1991; Gonzalez-Anaya etal., 2011), as is practiced at Kalgoorlie Consolidated Gold Mines, a joint venture between Barrick and Newmont.

Pressure oxidation is one of the main methods used in the industry to improve gold recovery from sulfidic ores. During the autoclaving process, iron sulfides present in the ore are oxidized to ferric sulfate or other oxidized solid compounds such as hematite, thus liberating the gold particles and making them available for leaching. Roasting is also widely used as an oxidative pretreatment for sulfidic refractory ores, in which iron sulfides are oxidized to hematite by oxygen at high temperatures; the porous characteristics of hematite allow for penetration of the cyanide leach solution. Another known method for gold liberation from the sulfide matrix is biological mineral oxidation. In this process, bacteria act as a catalyst for the conversion of iron sulfides in the ore to soluble ferric iron (Fraser etal., 1991). These refractory oxidation processes may be carried out on either a sulfide concentrate or whole-ore feed.

The presence of carbonaceous matter in the ore has also been identified as a cause for the refractory behavior of some gold ores. Like activated carbon, the carbonaceous matter can adsorb the gold cyanide complex, thus reducing the recovery of gold in a cyanide-based process. During the leaching step, once the gold-cyanide complex is formed, it is readily adsorbed by the carbonaceous matter in the ore, thus reporting to the tailings instead of the pregnant solution or activated carbon. The carbon components of the ore responsible for this preg-robbing effect have been identified mainly as native or organic carbon (or noncarbonate carbon), often referred to as total carbonaceous matter (TCM). Encapsulation of gold by carbonaceous ores has also been associated with lower gold recoveries from these types of ores (Dunne etal., 2013) (see also Chapter 49).

The use of adsorbent media such as activated carbon (in carbon-in-leach (CIL)) or resin (in resin-in-leach (RIL)), to compete with the TCM in the ore for gold adsorption from the cyanide leach solution, allows for acceptable gold recoveries from ores with mild preg-robbing characteristics. In the presence of ores with higher TCM content, surface modification or oxidative pretreatments are required (Afenya, 1991).

Traditional methods for pretreatment of carbonaceous ores include flotation, the use of blinding agents, roasting, and chlorination. Flotation has been used to remove carbonaceous material from ores; however, this method is applicable if only most of the gold particles are not associated with the carbonaceous components (Dunne etal., 2013). Blinding is based on selective adsorption of certain chemicals on the carbon surface. Diesel oils, kerosene, paraffin wax, and different surfactants have been used to coat the carbon surface effectively, thus reducing the preg-robbing characteristics of the ore (Zhou etal., 2013). Successful examples of this practice include the Stawell gold mine in Australia (CIL) and the Penjom mine in Malaysia (RIL).

Roasting is the most suitable process to ensure the most complete oxidation of carbonaceous material; high temperature (500600C) and oxygen or air are used to convert carbon to carbon dioxide. Gaseous chlorine (Cl2), hypochlorite (OCl), and ozone (O3) may be used to deactivate the surface of the carbonaceous material in the ore. The mechanism of carbon deactivation is not well understood; it has been suggested that upon exposure to chlorine, the carbon surface is modified, forming carboxyl-type groups that passivate the adsorption sites or change the surface charge, thereby repelling the gold-cyanide ions (see Chapter 49).

Ores in which gold is associated with sulfides and with high carbonaceous matter content are considered double refractory. The northern Nevada region in the United States is a main area where this type of ore is found. Ores in the Carlin Trend District are characterized by the presence of submicroscopic gold (invisible gold) finely disseminated within a sulfide-rich matrix (mainly pyrite, arsenian pyrite, marcasite, and arsenopyrite) within carbonaceous material. Sulfide concentrations vary from 0.5% to 3.5% whereas the carbonaceous matter content can range from 0.5% to 4% total organic carbon (Zhou, 2013). Figure50.1 shows typical gold deportment of two double-refractory ores (a and b) compared with a nonrefractory oxide ore (c). The main gold carrier in the ore shown in Figure50.1(a) is pyrite; the ore has a total sulfide content of 1.43% and a TCM content of 0.94%. In the ore shown in Figure50.1(b), gold is present as native gold, associated with pyrite and arsenopyrite and also as surface gold or gold adsorbed onto the TCM surface. This ore has lower TCM content (0.58%); however, a larger portion of the gold is present as surface gold. This is just a small illustration of the variability of ore components and gold carriers, key factors on selecting the processing method for a given ore.

The elution or stripping properties of a resin is as important as its loading performance. The functional groups on resins have different properties, including the strength of the ionic bond; elution methods therefore have to be developed and optimized for each resin type.

Recognized methods of elution of strong-base resins use zinc cyanide, ammonium thiocyanate, or acidic thiourea. Although each method has advantages and disadvantages (Fleming and Cromberge, 1984), no single method seems to be appropriate for all cases. For example, Fleming (1989) used the zinc-cyanide method for a conventional strong-base resin (A161RIP) used at the Golden Jubilee RIP plant, while for a more selective resin such as Minix, the thiourea method is more effective. Advantages of this stripping procedure are that no regeneration of the resin is necessary and elution is faster, as illustrated in Figure32.2.

The most effective elution technique for Minix makes use of acidic thiourea after an acid wash (1M) to remove nickel, zinc, and some copper. The gold-selective adsorption characteristics of Minix, particularly its high selectivity against cobalt and iron, make it possible to use its advantages (fast kinetics and circuit simplicity) without fear of poisoning the resin (Fleming and Hancock, 1979), as is the case with other commercially available strong-base resins. Elution can be improved by an increase in the thiourea concentration, the acid concentration or the temperature. With an eluant containing 1M thiourea and 0.5MH2SO4 at 60C, elution efficiencies of more than 99.6% can be effected within four or five bed volumes of eluant. Using this elution strategy, the resin is easily stripped to below 100g/t of residual gold.

Electrowinning has proved to be an effective and simple method for recovering gold from the eluate. Electrowinning is done simultaneously with the elution. The barren eluate is recycled to the eluant tank and is recycled for the next elution after the reagents have been made up to their relevant concentrations. Two operating plants, namely Penjom Gold Mine and Barbrook Gold Mine, have now demonstrated the feasibility of this elution strategy for Minix with simultaneous electrowinning.

[Ed.: Caledonia Resources announced5 in January 2006 the commissioning of Barbrook Gold Mine plant expansion, including ultrafine grinding, oxidation, and RIL circuits, and in November 2006 was placed on care and maintenance as a result of damage caused by employees of a labor brokerage company during an illegal industrial action.6 Barbrook was sold7,8 to Vantage Goldfields in 2008.]

Elution of AM-2B resin is similar to that of Minix; but a longer elution time seems to be required (Bolinsky and Shirley, 1996). The process includes a series of elutions, contacting the loaded resin with different solutions. The elution flowsheet differs from plant to plant, and some of the steps described below are optional. Usually the following steps are carried out:

All of the stripping operations are carried out at 5560C and atmospheric pressure. The original design of the stripping section required up to 288h (12days) for elution before achieving gold recovery. In the 1980s, a new stripping technique was developed, which takes from 12 to 24h, a considerable improvement over the original design. Gold from the pregnant thiourea solution is recovered by transferring the solution from the elution section to holding tanks for an electrowinning section. During electrowinning, the solution is circulated between the holding tanks and electrowinning cells. Residual gold on the stripped resin is expected to be below 100g/t.

Combining the elution and electrowinning operations enables elution of AuRIX 100 to be achieved by continuous electroelution using an eluate solution based on 1M sodium hydroxide at 60C (Mackenzie, 1993). In this process, the eluate is passed through a bed of resin and is continually recycled through an electrowinning cell back to the resin bed. In some instances, an improvement to the elution rate can be obtained when the alkaline eluant contains a low concentration of alkali metal cyanide salt and an alkaline salt of a carboxylic acid such as sodium benzoate (Virnig, 1996).

The elution of AuRIX 100 resin was studied exhaustively in a pilot plant in Mexico (Fisher etal., 2000). Initially, resin elution was performed with an eluate composition of 40g/L NaOH, 70g/L sodium benzoate, and 100mg/L free CN. Total eluate volume in the circuit was 64L. Sodium benzoate was found, in bench-scale testing, to accelerate elution kinetics. Elution was carried out at 60C for 6h. At termination of elution, the difference between the gold concentration in the eluant entering and the eluate exiting the column was less than 1mg/L Au. Elution profiles (eluate exiting the column) typical of the sodium benzoate-containing eluate are shown in Figure32.3. Loaded and eluted resin analysis for a sample using this eluate is given in Table32.1.

Elutions were also carried out without sodium benzoate. Figure32.4 shows the effect of sodium benzoate in altering the elution profile. At the end of 6h, the same differential between the eluant entering and eluate exiting the column (less than 1mg/L Au) was obtained. Therefore, sodium benzoate was not a necessary addition for elution of AuRIX 100. Eluate produced by this type of resin is suitable for conventional gold electrowinning with single-pass efficiencies of 66.591.7% and overall gold recovery in electrowinning of 94.599.8%.

A conventional strong-base resin (Duolite A161L) was used at the Golden Jubilee Mine for the recovery of gold, primarily due to the fact that no gold-selective resin was commercially available in the western world at that stage. The zinccyanide elution process is suitable for all nonselective strong-base resins. It is a reversible reaction and therefore, in order for the reaction to proceed to completion, it is important that the concentration of gold in the eluate should be kept as low as possible. This can be done either by the use of a very large volume of eluant, which is pumped in a single pass through the elution column (this is clearly an impractical and expensive approach), or by the use of the electroelution method, in which eluate solution is recirculated continuously between an electrowinning cell and the elution column. The latter approach was adopted at Golden Jubilee (Fleming and Seymore, 1989) and made use of the Mintek-designed electrowinning cell.

In the Golden Jubilee elution, 1 bed-volume of solution containing approximately 0.6M Zn(CN)42 was recirculated from a surge tank through a heating box, elution column, and an electrowinning cell, back to the surge tank. After about 6h of elution at 60C, zinc oxide and sodium cyanide were added to the eluate to compensate for the zinc cyanide that had loaded onto the resin and to restore the concentration in solution to the starting value of 0.6M.

The major disadvantage of the zinccyanide electroelution process is that it is slow; for the first 6months, each elution cycle was continued for a period of 45days. However, since only one elution was necessary per week, the slow elution did not create a bottleneck in the process. Moreover, it was possible to systematically reduce the elution time over 12months of operation, mainly as a result of improvements to the efficiency of the electrowinning process, to attain an ultimate elution period of 48h.

After elution, the resin was washed with water to remove entrained zinc cyanide solution and the resin was then regenerated with 1M sulfuric acid solution. The spent regenerant solution, containing zinc sulfate saturated with hydrogen cyanide gas, was pumped directly into a stirred lime slurry. The zinc cyanide that was produced during this neutralization reaction could be recycled to elution.

Vitrokele is a generic name given to the specialist technology that has been developed for the recovery of cyanide from precious-metal plant process streams (Signet Engineering, 1996) and the recycling of cyanide within the circuit. The resin that has been developed for gold-processing applications, Vitrokele 912, is manufactured by Rohm & Haas in France [Ed.:now part of Dow Chemical Company]. It is understood that the technology was commercially applied at the Connemara plant in Zimbabwe for gold recovery by means of resin-in-solution (RIS) and that significant capital cost savings were realized by use of the resin in place of the conventional activated-carbon process. The flowsheet given for the process suggests that similar chemistry to that used at the Golden Jubilee plant (Fleming, 1989) was employed. Therefore, it is thought that the resin used was probably a strong-base anion exchanger similar to the A161L resin.

Saint-Gobain Zirpro has been instrumental in the development of ceramic media for ultra-fine grinding applications in stirred mills. The history and experience are long, dating back to the mid nineteen seventies. The company was in-fact established in 1971 to refine Zirconium Oxide to meet the Saint-Gobain Glass requirements for high performance refractories. The history of the Glass division is somewhat longer and it celebrated its three hundred and fiftieth anniversary last year.

Zirconia (Zirconium Oxide) and Zircon (Zirconium Silicate) turned out to be significant raw materials necessary to manufacture high quality ceramic beads. Initially beads were produced by a fusion process; the operation required high temperatures and the beads were formed in a molten state. The resulting product (ER120) was based on Zircon and had a density of 4.0g/cc. The beads were round and non-abrasive and were ideal to replace the glass and natural sand products used in the burgeoning stirred or bead mill applications. A comparative increase in density of over 50% was the important factor; greatly enhancing the productivity of the mills. Higher density media, such as steel (7.5g/cc) for example, were largely discounted due to increased abrasion rates and contamination. Therefore ceramic technology was readily adopted by major industries, including pigments, paints and agrochemicals. The products proved to be extremely successful and remained at the forefront of the technology for over twenty years. Increased demands on milling technology were however inevitable and eventually faster, finer, more precise targets were expected. The industry responded with the development of new mill designs which operated at higher speeds, with higher energy and higher throughput rates. A new type of bead was required which would be tough and could withstand the new operating conditions. The result was the evolution of sintered beads, initially based on the same chemistry and having the same density as the fused products. These beads required low temperature forming before densification (sintering) at high temperature. The products proved to be suitable in many of the new applications, providing tougher beads with extended bead lifetimes. Zirpro again developed a class leading product (RIMAX) which gave exemplary performance in many varied fields for example cosmetics, inks and automotive coatings. Today the evolution has continued with the general acceptance of high density (6.0g/cc) stabilized Zirconia beads as the media of choice (Hassall and Nonnet, 2007). The higher density provides the potential for superior and economic grinding and although initially expensive, the controlled wear provides an overall cost effective solution. Zirpro developed a premier product ZIRMIL now widely adopted and widely used in the processing of the most demanding applications, such as pharmaceuticals and ceramics.

Mill design has also evolved to meet the ever increasing demands for ever more specialized materials and applications. At the forefront of these developments are two extremely different projects; the first is nano grinding of electronic materials and the second the ultra-fine grinding of ore bodies in the mining industry. For nano grinding, beads sizes of approximately 100m are required and potentially bead densities increasing beyond of 10g/cc. For mining the environment is severe and beads must withstand high impacts from hard and large feed materials in dilute slurries.

In the nano application Zirpro has launched a derivative of the ZIRMIL range. Advanced ceramic technology and process engineering have enabled the production of 100 and 200m beads in industrial quantities at economic price levels. The material is currently under evaluation in extended customer trials. For mining a composite material MINERAX has been developed and successfully launched into the industry (Fig. 1). It is a tough composite material with a classic density of 3.9g/cc and fully competent in all ultra-fine mining applications.

The Albion technology, schematized in Fig. 14, was developed by Xstrata Plc to treat concentrates produced from refractory base and precious metal ores. The technology is a sulfate based process employing ultrafine grinding (P80 of 1015m) at temperatures of around 8590C, atmospheric pressure to accelerate the kinetics and increase copper recovery level from chalcopyrite, in conventional agitated tanks with corrosion resistant alloy steel shells (Nazari et al., 2012a; Kowalczuk and Chmielewski, 2008; Ellis et al., 2008). The Albion process is an auto-thermal operation, i.e. the leach slurry temperature is set by the amount of heat released in the leaching reaction.

Both the Albion and ActivOx processes make use of ultrafine grinding to achieve sulfide dissolution (enhanced matrix attack) at lower temperature and pressures than required by conventional high pressure oxidation (Ellis et al., 2008). Note that fine grinding produces particles with P100 of <38m while ultrafine grinding produces particles sized within 1 and 20m range (La Brooy et al., 1994). Ultrafine grinding performs the same function as roasting, pressure oxidation, bio- and chemical oxidation which is to break down the sulfide matrix to liberate precious metals locked in silicates or other minerals (Flatman et al., 2010).

According to Hourn et al. (2005), ultrafine grinding of sulfide minerals to particle size of 80% passing 812m will eliminate mineral passivation by sulfur precipitates, as the leached mineral will disintegrate prior to the precipitate layer becoming thick enough to passivate it. The oxygen used for oxidation is injected into the base of the Albion leach reactor at supersonic velocity to achieve the required mass transfer and leaching rate. Chalcopyrite is acid leached through ferrous ion oxidation (Fe3+ being the main oxidizing agent) by oxygen according to the mechanism suggested by Hiroyoshi et al. (2001) in Eqs. (17) and (18). Ferrous oxidation by oxygen takes place as in Eq. (19).

Copper is extracted via SX-EW to produce copper cathodes (Kowalczuk and Chmielewski, 2008). Excess sulfide sulfur in chalcopyrite leaching is present in the residue as elemental sulfur. This makes precious metals recovery difficult as S0 can form a protective coating on the mineral particles. Once present, the coating may hinder the leaching process or even stop it completely. Jeffrey and Anderson (2003) and Lu et al. (2000) have suggested non-cyanide leaching methods such as sodium hydroxide to overcome elemental sulfur issues.

Oraby and Eksteen (2013) have shown that one can leach copper sulfides (including chalcopyrite), oxides and native copper effectively from a copper mineralprecious metal concentrate using an alkaline glycine solution at pH of 1011 with hydrogen peroxide as oxidant. The copper glycinate solution can be treated for copper recovery by a number of conventional technologies such as precipitation using NaSH or solvent extraction. Elemental sulfur formation is prevented by performing the oxidation in alkaline glycine solution.

Hourn et al. (2005) have reported that Albion leach process can operate under either acidic or alkaline conditions (see Fig. 14). In the first case (acid leach), base metals are extracted along with precious metals as by-product, while in the second case; precious metals encapsulated in pyrite, arsenopyrite, selenide or telluride ores are alkaline leached with no requirement of recovering base metals. The alkaline leach process of refractory precious metal bearing sulfides such as pyrite progresses through pyrite dissolution (Eq. (20)) to finally expose the precious metals for subsequent cyanidation.

The Albion process is commercially operational at two plants treating zinc sulfide concentrates that are located in Spain and Germany, while a third Albion process plant operating in the Dominican Republic is treating refractory gold/silver concentrates (Turner and Hourn, 2013).

Uwadiale (1990a) used selective oil agglomeration to upgrade Agbaja oolitic iron ore from a feed value of 45.6% Fe to a concentrate containing 65% Fe at 89.3% Fe recovery. The ore was very fine grained and ultrafine grinding (<5m) was required for liberation. The main iron mineral was goethite with minor hematite and maghemite. Reagent additions were 5mL of oleic acid, 5mL of 10% NaOH and 0.07g of sodium silicate added to the grinding charge of 50g. The pH of the ground pulp was adjusted to 9 and 7mL of kerosene added before agitating the charge in a blender. At the end of the agglomeration process the slurry was screened at 38m to separate the agglomerates from the siliceous gangue. At pH 11, no agglomerates were formed.

vertical stirred ball mills - crushers, ball mills and flotation cells for mining and mineral beneficiation

JM series stirred ball mill have adopted by the gold ore, copper ore, silver ore,molybdenum ore, lead zinc ore, manganese ore, iron ore, nickel ore, such ore dressing plant for fine grinding or regrinding operations.

JM series stirred ball mill is a kind of high efficiency ultrafine ore grinding equipment (also called tower mill or vertical spiral stirred ball mill), mainly adopted for the ultrafine grinding test research, also for the small scale industry grinding production, to provide reliable technical parameters for industrial production. JM series stirred ball mill have adopted by the gold ore, copper ore, silver ore,molybdenum ore, lead zinc ore, manganese ore, iron ore, nickel ore, such ore dressing plant for fine grinding or regrinding operations.

1.1, high ability of fine grinding, to grinding the material to be 1m or more fine 1.2, High efficiency and energy saving, more than 50% energy saving compared with horizontal ball mill, the working efficiency is 10 times than horizontal ball mill. 1.3, Product output size can be adjusted, could be working continuous operation, batch operation, recycling operation. 1.4, Simple structure, easy operation and maintenance, small footprint, the foundation cost is less than 1% of the machine cost.

2.1, Adopting The vertical spiral stirred mill to grinding the gold ore, and the same time leaching operation, can extract gold economically with low cost and high gold recovery. 2.2, Applied for the second stage ore grinding, the fine grinding of sulphide ore and the tailings recycling, could economically grind ore to -400 mesh more than 90%-95. 2.3, Ultra fine size grinding is available, could grinding the ore to the size less than -10m.

1.the components of the raw material, density 2.Feeding size (um) 3.The expecting size output (um) 4.Voltage and frequency 5.Open circuit or close circuit ? 6.Feeding pulp density %? 7.The max and lowest temperature of the mining site 8.other requirements

ZJH mainly focus on producing and supply crushers, ore grinding equipment, mineral Beneficiation equipment, laboratory and pilot scale ore dressing equipment for Mining and Mineral Processing Industry. Our aim is to work together with Mines, Mineral Beneficiation Plantsfor helping to reduce the operating cost ,to improve the operating efficiency.

screening media | mineral screening multotec

From wedge wire sieve bends and centrifuge baskets to completely optimised composite screen decks, Multotec is a leading screening media technology solutions provider for the global minerals processing industry.

We supply products covering the full range of screening applications, including sizing, dewatering, scalping and desliming. Refined over 45 years experience in mineral screening applications, Multotec manufactures one of the worlds largest ranges of rubber, polyurethane, wedge wire, steel and composite screening media.

Your local Multotec branch provides turnkey screening media solutions, with short lead times on screening media products, and engineering and field services to ensure your screening plant is optimised for your processing conditions, material and the output targets.

Multotec screening media has been developed in response to the worlds toughest mineral screening applications. We offer this global technology to the worlds mining and mineral processing houses through an established worldwide footprint that includes a complete network of branches and distributors in almost 100 countries on 6 continents.

Your local Multotec experts offer complete turnkey solutions for screening media installations, including design and engineering, installation and commissioning, and wear monitoring and field service support. Our teams will ensure the optimum screening media solution is supplied according to your specific plant and process parameters and requirements, such as feed tonnage required, the average particle size and the particle shape.

Multotec can design and build completely customised screening decks. Drawing on one of the worlds largest ranges of purpose-specific screen panels from materials including rubber, polyurethane, steel, woven-wire, ceramics, Hardox, fibreglass and combinations of these materials we can optimise each area of your screen deck to suit the conditions, your material and output targets.

A popular composite deck configuration is to place a set of panels with highly impact-resistant material at the feed end of the screen, where the impact of material from the feed box or chute is highest.

Weve supplied composite screen decks with over a dozen different types of panels, with each panel fulfilling a specific function. The apertures will be chosen according to the screens purpose and factors like the feed tonnage required, the average particle size and the particle shape. That way, we can ensure maximum mineral screening efficiency at the lowest overall cost.

Our monitoring software Hawkeye provides complete real time and historical intelligence of the condition of your screening media. Through accurately indicating screen media wear, Hawkeye helps optimise wear-related maintenance and reduces downtime, while ensuring your screening media reliably delivers the cut size your plant required.

By enabling plant operations and technical teams to systematically manage and analyse wear data from the screening deck, Hawkeye also provides a powerful planning system for on-going application improvement. By tracking the performance over time of the various panel types on each deck in operation, the screening requirements in each part of the deck can be constantly refined.

Multotec screen panels are manufactured standard with visual wear indicators. These wear indicators comprise four or five moulded cavities in the body of the panel, spaced at predetermined intervals below the upper wear surface. As the panel surface is worn away, so the individual cavities become visible, the final cavity of which indicates that a replacement must be conducted or planned shortly.

This simple but innovative system, patented by Multotec, not only indicates when replacement needs to take place, but can be used as a data source to measure the rate of wear so that a future replacement time can be predicted and planned.

Blinding occurs when dirt, minerals and other substances adhere and bridge across the apertures of your screening surface, creating a stubborn paste that blocks material from screening through. Pegging describes the presence of irregular material lodged in the screen apertures, and occurs when stones are about the same size as the holes.

Multotec, in partnership with universities across the globe, is constantly developing and testing new innovations and technologies to respond the challenges our customers face in processing minerals more efficiently, and at a lower cost. Our screening equipment of today reflects over 45 years of innovation and optimisation in the worlds largest mining and mineral processing operations.

Roy has been involved in mining and metallurgy since 1981, and has vast global experience in both the production and sales side of the industry, across Africa, Australia and South America. His commitment to product development, business development and customer satisfaction has made Roche one of the worlds leading experts in screening media solutions.

mushroom - super mario wiki, the mario encyclopedia

Mushrooms are recurring items in the Mario franchise. Their effect on the player character varies from game to game. In both the Mario Kart and Mario Party series, the Mushrooms share an appearance with the Super Mushrooms from the Super Mario series.

Mushrooms,[1] also known as Sub-space Mushrooms[2] or Subspace Mushrooms,[3] add an additional mark or heart to the life meter, up to four. Additionally, the Mushrooms also turn Mario, Luigi, Peach, and Toad back into their Super forms if they are in their Small forms in the same manner as a Super Mushroom or a small heart, and the health meter is refilled upon collection. Mushrooms are found only in specific Subspace locations within the stage.

In the Mario Kart games, a Mushroom (or Speed Mushroom[4]) is an item that grants the Kart a burst of speed and allows the player to drive through off-road surfaces without slowing down. Mushrooms can come in singles or triplets, the latter providing three Mushrooms to use in a row. In Mario Kart: Double Dash!!, a character holds these mushrooms in piles, but if the kart is hit by an item on the road, these mushrooms will fall off and the character will be left with just one. Normally this set appears as default power-ups in time trial mode (excluding Super Mario Kart) to use specially over shortcuts of a determined course, though in Mario Kart: Double Dash!!, the player is only given two to use rather than three, and in Mario Kart DS, the starting amount depends on the kart's Item stat. Another type of Mushroom is the Golden Mushroom, which can be used indefinitely in a restricted period of time.

In recent Mario Kart games, Mushrooms can be used as well to knock over other karts or even steal an item from opponents by ramming them, as seen in Double Dash!!. In later games, this move cannot steal items, but it works to steal balloons, Shine Sprites, or coins from other players during a battle. In Mario Kart 64, using a Mushroom and ramming into other racers will cause them to spin out.

From Mario Kart Wii onwards, it can be used to avoid the Spiny Shell; however, it is difficult to obtain a Mushroom in first place. The Mushroom artwork from Mario Kart Wii is reused from the Super Mushroom artwork for New Super Mario Bros.

In Mario Kart 8 and Mario Kart 8 Deluxe, the Mushroom is slightly more powerful than it is in other games. It also receives a new visual effect; the boost will create a line of flames between the road and the wheels, and it causes the engine to rev louder and higher. When obtained as a set of three, they now revolve around the vehicle, in the same way as the Triple Shells, and other racers that drive into them will feel their effect immediately without causing one to disappear. Mushrooms also have a sponsor named after them, Mushroom Piston.

In addition to single mushrooms, Triple Mushrooms are also included in Mario Kart Tour as the special item of Toad, Toadette, Mario (Classic), Peach (Wedding), Mario (SNES) and Luigi (Lederhosen). Unlike most other games, the mushrooms are used up all at once, providing a similar speed boost for a longer period of time than a normal Mushroom. Additionally, single mushrooms are now automatically trailed behind the player's vehicle, meaning other racers that drive into it will feel its effect, similar to the Triple Mushrooms in Mario Kart 8 and Mario Kart 8 Deluxe.

In Mario Clash, defeating thirty target enemies will cause a Mushroom to spawn from the pipes. This item will initiate Fever Time, which allows Mario to defeat any enemy with a single throw and doubles all points. The effect ends if Mario loses a life or the shell and when he finishes the stage.

In Super Mario RPG: Legend of the Seven Stars, a basic Mushroom can be accumulated in the inventory and recovers 30 HP for one party member. This Mushroom has a red and white cap with an orange stem and no face. However, mushrooms that have faces are found in treasure boxes, and they automatically recover all HP and FP for Mario's entire party once uncovered. Most of these treasure boxes restock once the area is entered again. Other types of mushrooms exist, including two other increasingly expensive kinds used for basic recovery. The Mid Mushroom recovers 80 HP to one party member, and they have a green cap rather than a red one. The Max Mushroom is able to recover all HP to one party member and has a yellow cap. In the Japanese version, the Mid Mushroom and Max Mushroom are respectively known as Super Mushroom and Ultra Mushroom, which would become the terminology used in future RPGs.

There are mushrooms indistinguishable in appearance but instead cause negative effects on allies and adversaries alike. The Bad Mushroom, only found in Seaside Town, does not recover HP and is used only in battle. When used, they poison an enemy of choice, but some enemies are resistant. Another mushroom is sold by the Goombette Triplets at the shop in Monstro Town. These mushrooms, apart from restoring 30 HP, actually turn the user into a Mushroom (a status ailment also caused by certain enemy actions). While a mushroom, the character recovers health every turn, but is completely immobilized.

Mushrooms appear as items in the Mario Party series. The first time they appear is in Mario Party 2 (where they are Mario's favorite item), and they have reappeared in other Mario Party titles. In Mario Party 4, Mario Party DS, and Mario Party 8, the item is not present (although there are similar items, such as Mario Party 4's Mega Mushroom, and Mario Party 8's Twice Candy). They allow for two rolls of the Dice Block during one turn. If the two digits rolled are the same, the user will receive ten Coins. If the user happens to roll two 7's, they will receive twenty Coins. If players want to purchase this item, the price will usually be five Coins.

In Mario Party Advance, their effect is different. In this installment, Mushrooms allow the player to roll the Dice Block. Each turn, a Mushroom will be depleted from the stock. For players to win Mushrooms, they have to win minigames. Players will usually receive three Mushrooms when they win a minigame, although there are cases in which the award for winning a minigame will be six Mushrooms. The game ends when the player doesn't have any Mushrooms left.

While Mushrooms themselves do not appear in Mario Party: Island Tour, Mario Party: Star Rush, Mario Party: The Top 100, and Super Mario Party, a derivative referred to as a Dash Mushroom allows the player to add three spaces to the Dice Block total.

Mushrooms appear in the games Mario Tennis for the Nintendo 64, and Mario Power Tennis for the Nintendo GameCube and Wii. These staples can be used during an Item Battle match, which can be obtained when the player hits an Item Box with the ball over the net. In both games, Mushrooms make players run faster, but in the latter game, they can also grow players who have been shrunk by lightning back to normal size. In Mario Tennis Open for the Nintendo 3DS, tennis gear for Miis is designed based on a Mushroom. It is the emblem of the Mushroom Cup for all the previously mentioned games.

Mushrooms are the basic item for healing in Mario & Luigi: Superstar Saga. They are the cheapest item found in stores and the first item obtained. Their coloring is reversed in this game, with their caps being white with red spots; they also lack faces. Regular Mushrooms restore 25 HP, Super Mushrooms restore 50 HP, Ultra Mushrooms restore 120 HP, and Max Mushrooms restore all HP. Five special Golden Mushrooms can also be found in the game; the rare item restores all HP and BP. Shroom Badges and Shroom clothings that can be purchased at certain shops will increase Mario and Luigi's stats according to the number of Mushrooms in their inventory.

A unique mushroom called the Invincishroom (claimed to be a mix of 1-Up Mushrooms and Stars, but in the remake, it was actually a Poison Mushroom, as confirmed in the Minion Quest side mode) can be found only when the player has beaten the high score of a certain minigame. The player cannot use it, however, because Mario eats it as soon as he and Luigi win it, causing him to become very sick and slowly turn into a bean. Luigi cures Mario by giving him Crabbie Grass, which is found in Guffawha Ruins.

In Mario & Luigi: Superstar Saga + Bowser's Minions, regular Mushrooms heal 30 HP instead of 25 HP, Ultra Mushrooms heal 80 HP instead of 120 HP, and their designs are changed to be the standard design, as in the other Mario & Luigi games.

In Mario & Luigi: Partners in Time, Mushrooms act in the same manner as in Mario & Luigi: Superstar Saga; they restore HP for one member. While the Max Mushroom is still the same, the regular, Super, and Ultra Mushrooms heal 20 HP, 40 HP, and 80 HP, respectively. There are also items called Mushroom Drops, which will heal every single member on the team, very much like the Nuts in Mario and Luigi: Superstar Saga. Unlike Max Mushroom and Max Nuts, however, there is nothing more powerful than Ultra Drops. Shroom Badges make a return, but with a different effect: they now increase the healing effects of a Mushroom.

Mushrooms return in Mario & Luigi: Bowser's Inside Story and its remake, but Mushroom Drops are replaced in favor of the original Mario & Luigi series Nuts. Mushrooms act in the same manner as in the two preceding games. Mushrooms in this game heal 30 HP, Super Mushrooms heal 60 HP, Ultra Mushrooms 120 HP, and Max Mushrooms heal 240 HP instead of all HP like in the previous installments.

Bowser does not eat mushrooms unless a Goomba/Bob-omb from a Jailgoon or the Broque Monsieur "fight", a Trashure or Dark Trashure, or a Naplock gives him one, or he uses Refreshrooms, which recover half of his Health Meter (only when he is Giant Bowser).

Mushrooms return in Mario & Luigi: Dream Team. Regular Mushrooms heal 30 HP, Super Mushrooms heal 60 HP, Ultra Mushrooms heal 100 HP, and Max Mushrooms heal 160 HP. If Shroom EXP is used, then the value of the HP healed from using Mushrooms during battle will be converted to EXP at the end, but with a 50% bonus. Regular Mushrooms add 45 EXP, Super Mushrooms add 90, Ultra Mushrooms add 150, and Max Mushrooms add 240.

In Paper Mario, Mushrooms act as healing items, as in other Mario RPGs. In this game, they heal 5 HP when used. Several variations of Mushrooms could be found, such as Volt Shrooms and Life Shrooms. Recipes can also be made for other types of Mushrooms by combining certain ingredients together by Tayce T.

Mushrooms return in Paper Mario: The Thousand-Year Door. They heal in the same manner as in the previous game, with the addition that - now that Mario's partners have HP - mushrooms can restore a partner's HP also.

The many variations of Mushrooms from the previous game return, with the addition of Slow Shrooms. Small creatures named Punies commonly eat Mushrooms, shown by brother and sister Punio and Petuni. At the end of the game, Punio and Petuni give both Mario & Peach a Mushroom to enjoy on their boat ride home.

Unlike in the preceding games, Mushrooms cannot be bought in shops in Super Paper Mario. Instead, they are found out of ? Blocks and heal ten HP upon contact. They also give the player 1000 points. Their carry-on equivalent is the Shroom Shake.

In the fourth game of the Paper Mario series, Paper Mario: Sticker Star, Mushrooms appear, much like every other item, as stickers. They restore 20 HP, but if the button is pressed with good timing, the effect can be increased to 30. Two stronger Mushroom stickers also exist: the Shiny Mushroom, which acts like a Super Shroom, which restores 40 or 60 HP, and the Flashy Mushroom, which acts like an Ultra Shroom, which restores 80 or 99 HP. Big 1UP and Big Shiny 1UP stickers also appear, restoring 10 or 15 HP for 10 turns, respectively, as do Poison Mushrooms, which poison Mario, but enemies also get poisoned if they touch him.

In Paper Mario: Color Splash, Mushrooms appear as cards. They use up red paint when colored in, restore a small amount of HP when used, and cost 20 coins at Prisma Cardware. In addition to regular Mushrooms, Big Mushroom and Mega Mushroom cards also appear, which cost 70 and 150 coins respectively and restore more HP.

Mushrooms reprise their roles in Paper Mario: The Origami King, with their Shiny and Flashy variants returning from Sticker Star. This time, however, they don't appear as stickers, but in a physical, papercraft form. The regular mushroom is the most common and heals 50 HP, while the Shiny version heals 100 HP. When used in battle, they will occupy one of Mario's attack slots. All three variants can be found in ? Blocks throughout the game, and after one is found in the world, it then becomes available at Toad Town's item shop. They can also be bought at Overlook Tower and Big Sho' Theater. Mario can hold up to 99 Mushrooms, and unlike in the previous two games, they can be used outside of battle in almost any area. However, they are banned from Scuffle Island, cannot be used while riding down Eddy River, and will be burned by a Fire Vellumental statue when fighting the Paper Macho Shy Guys in the Fire Vellumental Cave. The Mushroom 3-Pack and Mushroom 6-Pack (which have Shiny variants of their own) are bulk items that can be bought in stores for a cheaper price than buying Mushrooms individually.

Mushrooms appear in the Nintendo DS version of Mario & Sonic at the Olympic Games, where they are once again referred to as Dash Mushrooms. They appear in the Dream Race event, where they give the player a short speed boost when used. In the Wii version, Dash Mushrooms appear as items in Dream Platform, where they give the character a five second speed boost when used.

Mushrooms appear as items in the Supersonic Downhill Dream Event in the Nintendo DS version of Mario & Sonic at the Olympic Winter Games. They appear randomly scattered throughout the course, and allow the player to perform a Mushroom Dash by pressing the B Button, which gives them a boost of speed. The player can store up to five Mushrooms at once.

Mushrooms appear in Mario Golf: World Tour as usable item shots. They make the ball roll much farther when they hit the ground. They are also seen as tee markers on the Toad Highlands golf course. Trophies for Castle Club tournaments, and the lampposts of the building's exterior, have models of Mushrooms. The Mushrooms are red on regional tournament trophies and their spots are the trophy's color, while on world tournament trophies, the Mushrooms have crowns on them and are completely colored like the rest of the trophy.