Some deposits can be worked by screening, (sizing) alone with no or very little crushing required. Others are crushing intensive requiring much work starting with drilling and blasting of the stone in the quarry. Consequently, crushing equipment requirements can vary greatly from one location to the next even though the same finished products are being made for the same market. This is apparent locally with the Quartzite quarries around Sioux Falls S.D. versus the local sand and gravel deposits.
There are basically two different styles of crushers utilized in our industry: compression and impact crushers. As their names suggest, compression crushers, (jaws, cones and rolls) reduce the material by squeezing or compressing it until it breaks. Impactors, (HSI and VSI) break the material by either striking it with a fast moving blow bar or by throwing it into a stationary anvil where it breaks upon impact. The choice between compression and impact crushing involves some tradeoffs; either type has its plusses and minuses.
8:1 maximum reduction ratio for compression crushing, this is normally used as a primary crusher. Jaws perform well in many materials. Yields low wear cost per ton in hard abrasive deposits, minimal fines but produces little finished (under 1) product which places more load on the crushers downstream in the circuit. Many producers refer to jaws as breakers meaning that they break the rock down to a size manageable for the secondary crushers. The numbers used in referring to jaw crushers, such as 3042, refer to the opening size at the top of the jaw. The 30 is 30 left to right, the 42 is 42 across the jaw. Allowable top size is approximately 80 percent of the left-right dimension, or in this case, 24. The width of the jaw determines capacity. Jaw crusher output gradation is controlled by the closed side setting. This is the adjustable opening at the bottom of the jaw. With a 24 top size limit and an 8:1 reduction ration, the closed side setting should be no smaller than 3. A well designed jaw should be 80 to 85 percent efficient. This means that 80 to 85 tons out of every 100 tons through the jaw will be 3 or smaller, in this case. The balance of the material will be plus 3-6.
8:1 maximum reduction ratio for compression crushing and is normally used as a secondary or tertiary crusher. Lower wear cost than imp actors. Good capacity down to around . Production drops off dramatically when producing smaller materials. Even with the new high-speed, high-throw cones. Cones can vary from 60 percent to over 80 percent efficiency. Crusher efficiency has a huge influence on productivity. As an example, lets compare two cones with 300 tph capacity, one at 60 percent efficient and the other at 80 percent efficient.
At the end of an 8 hour shift, cone 2 has put 480 more tons of material on the ground. Assuming a $5.00 per ton value = $2,400 more saleable product in one day=$12,000 more a week=$48,000 more a month=$288,000 in six months
This is at $5/ton. Value could easily be doubled depending on what the finished product is. Crusher efficiency is not often discussed during the sales process which is too bad, as it is very important.
Some of the cone nomenclatures are 4, 4 1/4, 44, 45, 52, 54, and 66. These refer to cone diameter: the larger the cone, the higher the capacity. The foot numbers refer to Symons Machines, the inch designations are most commonly Telsmith and Cedarapids cones. Metso Hp300, Hp400, and Hp500 refer to the horse power connected to the cone. Cedarapids Mvp280, 380, 450 and 550 refer to the cone capacity at 1 closed side settings. It seems everyone does it a bit different.
The Crushing action of a cone comes from eccentric motion of the shaft or head. There are two basic cone types, bushing or bearing. The bearing cones run cooler and more efficient, thus putting more of the applied Hp to work crushing rock rather than creating heat. The bushing cones require more lubricating oil and larger, more active oil coolers, but are less expensive to build and rebuild. The debate as to which is better has been waged for decades with no end in sight.
The most often replaced components in a cone crusher are the wear liners. The moving portion is called the mantle. The stationary liner it crushes against is called the bowl. Both are made of manganese steel, as are jaw dies. Good quality manganese will harden to 500-550 Brinell hardness. Jaws and cones are somewhat related as a cone could be thought of a jaw tipped on its side and made round. Both derive their crushing action from eccentric motion.
As much as 24:1 reduction ratio and are often run as primary or secondary crushers, occasionally tertiary. Normally are used with soft to mild stone. If utilized in hard abrasive materials, the wear cost and associated downtime is normally not acceptable. Output graduation of typical Hsi primary application will have around 40 percent finished size (-1) material. Much more finished product than a jaw primary. Thusly, the circuit capacity is increased and the load on the crushing equipment downstream is minimized. Hsi crushers can produce and excess of fines in soft material, they can be dusty during operation. Hsi crushers are very popular in recycle applications as the can be run by themselves with no secondary crushers. They also offer far better iron liberation in concrete recycle work than do jaw crushers.
Hsi output gradation is controlled by rotor speed (rpm or tip speed in fpm). More speed results in a finer output. Apron or gap settings and the number of blow bars in the rotor also effect the output gradation, more bars equals a finer output. A smaller gap setting results in a finer output gradation as well. Rotor construction can be open or solid, cast or fabricated weldment. Blow bars are made from a variety of materials: manganese, low chrome, high chrome, and high chrome ceramic. The harder the bar, the longer the life, and the lower the wear cost will be. However, the harder the bar, the less shock load from tramp iron or excess top size it will tolerate. It is all about tradeoffs.
Typically used as a second, third or fourth stage crusher. Canica offers a model that will accept a 12 top size which allows it to be used as a primary in some applications. The Vsi is easily the most misunderstood and misapplied crusher in the marketplace. For approximately every 15 to 20 cones that are sold, one Vsi is sold. They are hard to sell due in large part to poorly configured installations in the past.
Vsi nomenclature used to loosely refer to the diameters are numbers like 66, 74, 80, 90, and so forth. Today the numbers like 2050, 2500 and such dont refer to anything as far as I can tell. Just a number selected by marketing that sounded racy.
The Vsi crushes material by throwing it against a hard steel anvil, which is where 95 percent of the crushing occurs. A Vsi (or Hsi) will give better product shape than a compression crusher, leaving a more cubical product like dice. Either impactor will also provide product beneficiation by crushing and deleterious in the deposit to dust, thereby leaving behind only the best, strongest stone in the stockpile. The Vsi will produce the best product shape of any of the crushers available today. It also has the best rate of production of the smaller sizes (- ) as it is the only crusher that does not close off the discharge side to make smaller product.
The challenge with the impactors is to control wear cost in hard abrasive material and to control excess fines production in soft stone. Both can be accomplished successfully more often than not. As with Hsi crushers, Vsi crushers move a lot of air and can be dust makers. They are a wonderful tool when properly applied. Gradation is controlled by table speed, number of shoes, shape of shoes, feed rate, and feed size.
3) If screen is 100 percent efficient and is removing all the smaller material then all of the stone will go back into the box. If only enough material goes back into the box to fill it the way, the screen is operating at 75 percent efficiency. Screens are the cash registers of the circuit. Having them operating at peak performance is critical. Screen speed, throw and angle can be adjusted on most screens. Consult the manufacturers manual for adjustment procedures. In general, screening large material requires a slower speed and higher throw. Fine screening requires more rpm and less throw.
3) Work material around by hand and place the oversize back into the box. If the box is 1/3 full, for example, the crusher is operating at 65 percent efficiency. Modern high-speed, high-throw cones should be around 80 percent efficient when properly adjusted and choke fed. A good starting point for impactors would be around 70 percent when producing typically sized aggregate products. Most new cones have a gauge to tell the operator what the closed side setting is. However, older cones do not. Neither do the jaws. Here is where the tinfoil comes in at.
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
Impact crushers reduce mineral materials such as concrete, asphalt and natural rock in size to produce a valuable commodity product. A fast spinning rotor throws the material against a solid stationary impact wall. The striking and impacting causes the material to shatter into smaller pieces. The result is a very homogenous and cubical product leaving the crusher box.
The horizontal shaft impactors are the most common impactor type that can be used in recycling, primary and secondary crushing applications. This type impactor will take reasonable size pieces and produce small output material.
The crusher box includes a rotor with hammers (also called blow bars). Depending on the rotor style you will have either 3 bars or 4 bars. Hammers are cast iron replaceable wear parts that are actually in contact with the material. They are designed to withstand the many impacts of the material. The impact wall (also called apron) has several crushing stages and is armoured by thick wear plates.
Once the hammer hits the big material entering the crusher box it is thrown against the wall and starts ricocheting between hammers, wall and other material particles. As soon as the material is small enough the fit in between the rotor and the lowest crushing stage of the impact wall it will leave the crusher box at the bottom.
The beauty of impact crushers is their versatility in terms of input material and output size. There are many different designs out there but generally speaking impact crushers can produce material from 3" down. The smaller the input material the harder it gets to crush. The output gradation can be adjusted through various settings.
On most crushers this works hydraulically. The aprons need to be adjusted when you want to produce a different output material or when you need to readjust your crusher settings to accomodate the wear progress.
RUBBLE MASTER impact crushers use a simple design to change the crusher setup easily, quickly and safely within minutes. The unique proprietary crushing chamber design allows operators with limited impact crushing experience to operate our machine efficiently from day one.
There are different types of stone crushers in mining industry such as jaw crusher, cone crusher, impact crusher, and sand making machine. This article will tell you how to maintain the 4 types of rock crushers and how to efficicently improve their performance.
Many stone crusher operators have a common coception that is "don't-fix-it-if-it-isn't-broke". They may want to save cost at the begining while the consequence is that they have to spend more money on repair and face interuption on production. That's why I always say that preventive and predictive is very important for all types of stone crusher.
Preventive means that by making regular checklist and inspections to keep crushers in good condition. Maintenance checklist is usually set up on a daily (8 hours), weekly (40 hours), monthly (200 hours), yearly (2,000 hours). Only doing that, can you prolong the machine's life span and maximize its value in crushing process.
Predictive refers to mornitoring the condition of crusher when it is running. By some maintenance tools such as lubricating oil temperature sensors, lubricating oil filter condition indicator, you can timely draw the machine data so that making a comparison between the real situation and normal state. Predictive can help you find problem early then timely removing thers issues before demage occuring.
Ractive means that even if your crushers have got problems, as long as you adopt correct solutions to respond, you still can get your machine back to normal. Next, I'll introduce important skills to maintain your equipment.
The cone crusher in the secondary or tertiary crushing proccess often fractures medium-hard or hard rocks like pebble, quartz, granite, etc. It is easy to get premature crusher failure, if operators cannot make a correct and timely inspection and maintenance.
Mantle in moveable cone and concave is fixed cone. Due to directly contacting with rock materials, the two wear parts need frequent maintenance and protection. So operators have to know the preparations and maintaining skills.
The working principle of impact crusher is that the spinning rotor under the driving of the motor can genetate strong impact force which make blow bars crush stone material into small pieces. Then the crushed material would be thrown by hammers towards, which makes another crushing process "stone to stone".
The sand making machine is also known as the vertical shaft impact crusher. Its working mode is that the material falls vertically from the upper part of the machine into the high-speed rotating impeller. The impeller is one of the important parts of the sand making machine, and it is also the most vulnerable part.
After the materials collide with each other, they will be pulverized and smashed between the impeller for multiple times and discharged from the lower part. The materials crushed by the device have an excellent particle size and are suitable for aggregate shaping, artificial sand making and highway construction.
In the face of such a dazzling market, how to choose the production equipment suitable for users' actual needs among the numerous equipment brands of many machinery manufacturers is a big problem for many large and small enterprises. Here we list top 4 world's construction equipment manufacturers for you to choose:
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.
Stone crushing can be classified into four stages depending on the degree to which the starting material is fragmented. These four stages are primary, secondary, tertiary and quaternary stages. Primary and secondary stages involve crushing of coarse materials while the tertiary and quaternary stages involve the reduction of ore particles to finer degrees. Activities at the primary stage will depend on gyratory, jaw or impact crushers. Cone crushers, roll crushers and impact crushers are mostly used at the secondary stages. The tertiary and quaternary stages mostly require the utilization of cone crushers, although some functions may require vertical-shift impact crusher. In order to control the size and quality of the product and at the same time reduce wastage, you must ensure that the reduction of aggregates is evenly spread over the four stages.
A gyratory crusher consists of a concave surface and a conical head constructed from heavy steel casting. It works by using a mantle that gyrates within a concave bowl. This rock crushing equipment uses compressive force to fracture the rock and this happens when the mantle makes contact with the bowl during gyration. Gyratory crushers are often built into a cavity in the ground and are mostly used to crush rocks that have high compressive strength.
A jaw crusher also uses compressive force and the materials are allowed into a gap at the top of the equipment between two jaws. One of the jaws is fixed while the other reciprocates by moving back and forth relative to the stationary one. The gap between the two jaws is known as the crushing chamber. The moving jaw exerts a compressive force against the stone in the chamber causing it to fracture and reduce. The rock remains in the jaws until is small enough to move down the chamber to the opening at the bottom. Jaw crushers can work on a range of stone from the softer ones like limestone to harder basalt or granite.
A cone crusher is similar to a gyratory crusher because it operates using a mantle that rotates within a bowl, but it has less steepness in the crushing chamber. It has a short spindle which is supported by a curved universal bearing located beneath the cone. They use compression force to break the rock between the gyrating spindle and the enclosing bowl liner. The rock becomes wedged and squeezed as it enters the top of this rock crushing equipment. The cone crusher breaks large pieces of ore once into smaller particles that fall to a lower position where they are broken again. The pieces are continually crushed until they are small enough to move through the narrow opening at the bottom of the crusher.
Roll crushers are a compression-type reduction crusher with two drums rotating about a shaft. The gap between the drums is adjustable. The particles are drawn into the crushing chamber by the rotating motions of the rolls and a friction angle is formed between the particles and the rolls. The stone fractures from the compression forces presented by the rolls as they rotate. The crushed particles are then forced between the rotating surfaces into the smaller gap area. Roll crushers are mostly used in smaller scale production to crush ores that are not too abrasive. This type of rock crushing equipment gives a very fine product size distribution with very little dust production.
Impact crushers do not use force to crush materials, instead, they use impact. The material is contained within a cage that has openings on the bottom or side to allow for the crushed materials to escape. Impact crushers can be classified into two categories: vertical shaft impact crushers (VSI) and horizontal shaft impact crushers (HSI).
VSI crushers use high-speed rotors with wear resistant tips that catch and throw the feed stone against anvils lining the crushing chamber. Rock is fractured along its natural fissures when its thrown against the anvils to produce materials with consistent cubical shapes.
The HSI crusher has a shaft that runs on a level plane through the crushing chamber. It works by impacting the rock with hammers that are fixed on a spinning rotor. It also works on the principle of throwing the stone to break the rock. Horizontal shaft impact crushers can be primary or secondary. They are better suited for softer, less abrasive stone in the primary stage and more abrasive and harder stone in the secondary stage.
Pilot Crushtec International (Pty) Ltd supplies a full range of cost-effective, heavy-duty, fit-for-purpose, horizontal shaft impact (HSI) crushers. These impact crushers are ideal for primary and secondary hard rock crushing applications in quarrying, mining, recycling, infrastructure and construction. Impact crushers from our range of mobile tracked and semi-mobile, skid-mounted equipment crush millions of tonnes of:
The Pilot Modular range consists of well-engineered, heavy-duty impact crushers mounted on skid-frames and designed for rapid installation and easy integration with the rest of our product range. They offer field-proven impact crusher technology, known for their high performance and simple maintenance, and can be easily adapted to most applications. The impact crushers feature a heavy-duty fixed hammer rotor, three high chrome heavy-duty blowbars, Hardox 400 Brinell liners and impact plates, and a feed chute with rubber curtains.
These mobile track mounted HSI crushers are ready to run, versatile impact crushers with instant set-up time, ensuring that customers generate income immediately. These solutions are diesel-driven and require no external power supply. The mobile impact crusher range consists of high-quality machines that provide a complete crushing solution without requiring any add-ons. They are cost-effective as they save installation costs and time and offer quick and easy reconfiguration of the plant for changing production demands.
Rubble Master, a world-leading range of compact recycling machines, fitted with high quality, powerful impact crushers that provide complete recycling solutions in versatile applications. They produce a high-quality, uniform, cubical shaped aggregate from construction debris, natural rock and asphalt. These high-performance compact crushers are ideal for contractors who require high mobility and are particularly suited for built up areas.
A range of tracked, diesel-driven, impact crushers provides an extensive mobile crushing solution, no matter the application. The efficiency of these machines has been proven throughout the world in a variety of conditions, providing customers solutions in quarrying, surface mining and construction applications.
To get up and running and start generating revenue quickly, add Pilot Crushtec Internationals horizontal shaft impact (HSI) crushers to your processing plant. Contact us for more detailed information.
Pilot Crushtec International (Pty) Ltd is South Africas leading supplier of mobile and semi-mobile crushing, screening, recycling, sand washing, stockpiling, compacting and material handling solutions. Our product range includes jaw crushers, cone crushers, vertical shaft impact (VSI) crushers, impact crushers, screens and conveyors.
Starting from the base working principle that compression is the forcing of two surfaces towards one another to crush the material caught between them. Impact crushing can be of two variations: gravity and dynamic. An example of gravity impact would be dropping a rock onto a steel plate (similar to what goes on into an Autogenous Mill). Dynamic impact could be described as material dropping into a rapidly turning rotor where it receives a smashing blow from a hammer or impeller. Attrition crushing is the reduction of materials by rubbing; primarily a grinding method. Shear crushing is accomplished by breaking along or across lines of cleavage. It is possible, when required, for a crusherto use a combination of two or three of these principles.
Rapidly increasing operating costs for minerals beneficiating plants continue to be the biggest single problem in maximizing profitability from these operations. The average world inflation rate has been increasing over the last decade and shows little sign of easing. The threat of continued increases in the price of fuel oil will eventually increase the cost of electrical power, in direct proportion for most users. This will undoubtedly cause closure of some lower grade ore bodies unless energy utilization efficiencies, particularly in comminution, can be improved.
Most of the recent literature concerning comminution performance improvement has been directed at grinding mill performance. It can be expected that more refined control systems will improve the overall milling energy efficiency, which is normally the largest single cost component of production. However, published gains by such methods to date appear to be limited to something less than 10%.
The second largest cost for comminution processes is normally that for wear metal consumed in grinding operations. Allis-Chalmers has continuing -research programs into all forms of comminution processes involving crushing and grinding. Improved crushing technology shows the way to reducing both energy and wear metal consumption mainly by producing finer feed which will improve downstream grinding mill performance.
A new testing procedure for studying crushing phenomena, presently being perfected by Allis-Chalmers, is described for the first time. These bench scale laboratory tests will give more accurate prediction of both energy requirements and size distribution produced in commercial crushing processes. As a direct result, this machine will allow more accurate comparisons to be made in capital and operating cost expenditures for various combinations of crushing and milling processes.
These new testing procedures can be run on small samples including pieces of drill core material. They could be part of testing and feasibility studies for most new concentrators. The same methods can be used to determine likely yield of various sized crushed products and, therefore, benefit crushed stone producers.
The theoretical and practical phenomena concerning comminution processes have received considerable attention in the literature and are not discussed here in any detail. Instead, the breakage studies in this paper are based on an empirical treatment of the fundamental relationships between energy and the size distributions of processed particles that have been observed both in the laboratory and in large-scale, commercial cone-crushing operations.
Because of the bewildering number of variables encountered when studying comminution processes, most investigators have preferred to assume that the size distribution generated in milling and crushing processes bears some relatively fixed relationship such as those described by Gates-Gaudin-Schuhmann1 or Rosin-Rammler.
Fred Bond, in his Third Theory of Comminution, used the former, essentially assuming that size versus cumulative percent passing that size was represented by a straight line of assumed slope 0.5 below the 80% passing size. Based on this assumption, Bond derived his well-known relationship:
The Work Index for rod and ball mills can be determined from laboratory tests and, as demonstrated by Rowland, the relationship gives us a reasonably accurate tool for the design of rotary grinding mill circuits.
Bonds methods have been less successful in predicting fine crushing performance, however, primarily because the typical crusher feed and product distributions do not meet the assumed conditions necessary for the satisfactory application of his equation (see Fig. (1)).
It is most evident that the curved lines appearing on Fig. (1) do not represent a Gates-Gaudin-Schuhmann size distribution. It is therefore not surprising that Bonds procedures do not work well in this situation. The Rosin- Rammler distribution has also been found inadequate to generally describe crusher products.
Work during the early 60s led to the concept of comminution as a repetitive process, with each step consisting of two basic operations the selection of a particle for breakage and the subsequent breakage of this particle by the machine. In this approach, the process under investigation is modelled by combining the particle selection/breakage event with information on material flow in and out of the comminution device.
Most workers who have used this approach have considered size reduction to be the result of the mechanical operation of the comminution device. This mechanical operation consumes the energy, and size reduction is merely a result of this energy consumption. This viewpoint is reasonably valid for tumbling mills where energy input tends to be constant and the proportion of the energy that is usefully consumed in particle breakage is low (<10%). It does not appear to be valid in compression crushers, however, since breakage energy is a significant proportion (>50%) of the total energy input to the crusher and markedly different power rates (energy input per unit of crusher feed) can be obtained by varying ore feedrates and/or crusher parameters such as closed side setting. It will therefore be necessary to include energy information in any model of the crushing process before it will be possible to accurately predict crusher performance. The inclusion of this energy-size information will significantly increase the complexity of these models.
The single-particle breakage event has been the subject of several studies. Most of these have utilized only sufficient energy to break the particle and do not simulate commercial crushing operations where energy levels are such that catastrophic repetitive breakage usually takes place. This approach to the study of comminution processes does yield valuable information, however, and it is unfortunate that it has not received greater attention.
The Bond Impact Work Index method has been an industry standard for the determination of crusher power requirements but was originally developed to ensure, that sufficient power was connected to primary gyratory crushers. In this method, pieces of rock are fractured by trial and error in the test device shown in Fig. (2), until sufficient impact energy has been applied to break the rock.
Normally, the rock breaks in halves, and in most tests only two and seldom more than three large pieces are observed after fracture. No size distribution information is used in calculating the Bond Impact Work Index from the formula:
KWH/tonne). The procedure works quite well for this type of crusher but tends to understate power requirements in fine crushers where power rates are typically much higher (upwards from 0.25 KWH/tonne).
Because of this, a research program was instituted by Allis-Chalmers Comminution Task Force Committee to break rock in a manner more analogous to that observed within commercial fine crushers. A pendulum type test device similar in most respects to that developed by the United States Bureau of Mines and shown diagrammatically in Fig. (3), was built and has been used in an extensive test program to determine whether it would be possible to predict cone crusher performance.
The rock samples selected for crushing in this device are usually minus 38mm (1-), plus 19mm () in size. The sample rock is weighed and then placed between the platens. The end of the rebound platen is placed in contact with the rebound pendulum and the crushing pendulum is raised to a predetermined vertical height which depends on the size of the sample. The crushing pendulum is then released after striking the crushing platen and breaking the rock, the remaining energy is transferred via the rebound platen to the rebound pendulum. The horizontal distance that the rebound pendulum travels is recorded by displacement of a marker and is subsequently converted to a vertical height.
where Ec = crushing energy E1 = crushing pendulum potential energy (before release) KE = kinetic energy of the two platens E2 = rebound pendulum maximum potential energy (after crushing) EL = system energy loss (sound, heat, vibration)
The system energy loss, EL, is determined by plotting EL as a function of the initial height of the crushing pendulum with no rock present. The major portion of this loss is by vibration. It is felt that the difference between system energy losses with and without rock present in the system is minimal as long as enough initial energy is supplied to result in a small elevation of the rebound pendulum.
The fragments from several rock samples broken under identical conditions were combined for each of the size analyses reported in this paper. Bond Work Indices were also backcalculated from the data using the standard formula, i.e.
Confirmation of the ability of the procedure to provide information suitable for the prediction of crusher performance was obtained by taking feed samples from 31 commercial operations treating a wide range of rocks and ores. At the time of taking a feed sample for laboratory testing in the pendulum device, relevant performance data such as power, feed rate and size distributions for feed and product were taken on the operating crusher. Several thousand rocks have been broken during tests with the device over the past 3 years.
The first thing to notice from these graphs is that there is an extremely good family relationship within each set of size distribution curves. This is somewhat coincidental, since the pendulum curve is the product of a single particle-single impact breakage event and the typical crusher product curve results from multiple particle-multiple impact breakage, but is probably due to two facts:
In order to show that the pendulum product size distribution is sensitive to power rate, several tests have been run on the same feed material at different levels of pendulum input energy. Typical results are shown in Fig. (7) as Schuhmann size distribution (log-log) plots. It can be seen that increasing amounts of fine material are produced with increasing energy input. The same effect was previously demonstrated for an operating crusher in Fig. (1). We can, therefore, conclude from this
that net power rates will be the same in the pendulum and the crusher when the two distributions coincide (as they do in Figs. (4) thru (6). This permits us to determine the efficiency of power utilization in crushers and to predict the product size distribution which will arise from operating crushers at different power rates.
The Bond Work Index figures obtained by backcalculation from the pendulum data are compared with the Net Work Index values obtained from the plants in Fig. (8). The agreement is surprisingly good especially in view of the fact that the 80% passing values do not completely describe the total feed arid product size distributions. This agreement is probably due to the fact that the use of comparable energy levels in both machines gives rise to similar reduction ratios and product size distributions. Because of this, the pendulum test provides a good estimate of the Net Work Index when this is required for current design procedures.
The pendulum product distribution is a breakage function and can be used in models of the process to predict crusher product distributions for different operating conditions. As an example of this approach, Whitens model of the cone crusher, Fig. (9), has been used to simulate the situation given in Fig. (4). The result of this simulation is given in Fig. (10) where it can be seen that very good approximations of crusher performance can be obtained.
The writers are firmly of the opinion that results to date prove that the use of this pendulum device can give more energy-size reduction information in a form readily useable for crusher application. The data can be generated in less time and from a much smaller sample than is required for pilot plant testing. Our present pendulum tester is a research tool and is currently being modified for use in commercial testing of minerals and rocks. More details of this device will be given at a later date.
All that time it took to design and build postponed your ability to generate income. What if we told you we've got a library of pre-engineered plants ready to build, rapidly install and produce profit?
Superior replacement crusher parts are taken from the same warehouse used for our manufacturing operations. That means you get an equal part, with equal quality, thats designed exactly for your machine.
Feedmaterial quickly contacts a series of blow bars spinning rapidly on a rotor. These blow bars (hammers) violently toss the rocks against steel curtains (aprons). Eventually, newly shaped rock exits the opening at the bottom of the HSI.
Compared to compression crushers like jaws and cones, horizontal shaft impactors will accept larger feed sizes, process a higher tonnage and allow excellent control of particle shape and size by simply adjusting the spacing of its internal components.
We always have been and always will be a privately-owned company. That means we can add more employees to our customer service team without Wall Street breathing down our neck. Isnt that the way it should be?
In the quarry, crushing is handled in four potential stages: primary, secondary, tertiary and quaternary. The reduction of aggregate is spread over these stages to better control the product size and quality, while minimizing waste.
The primary stage was once viewed merely as a means to further reduce stone following the blast or excavation prior to secondary crushing. Today, primary crushing is viewed as more important within the balance of production and proper sizing needs. The size and type of the primary crusher should be coordinated with the type of stone, drilling and blasting patterns, and the size of the loading machine. Most operations will use a gyratory, jaw or impact crusher for primary crushing.
In the secondary and subsequent stages, the stone is further reduced and refined for proper size and shape, mostly based on specifications to produce concrete and asphalt. Between stages, screens with two or three decks separate the material that already is the proper size. Most secondary crushers are cone crushers or horizontal-shaft impact crushers. Tertiary and quaternary crushers are usually cone crushers, although some applications can call for vertical-shaft impact crushers in these stages.
A gyratory crusher uses a mantle that gyrates, or rotates, within a concave bowl. As the mantle makes contact with the bowl during gyration, it creates compressive force, which fractures the rock. The gyratory crusher is mainly used in rock that is abrasive and/or has high compressive strength. Gyratory crushers often are built into a cavity in the ground to aid in the loading process, as large haul trucks can access the hopper directly.
Jaw crushers are also compression crushers that allow stone into an opening at the top of the crusher, between two jaws. One jaw is stationary while the other is moveable. The gap between the jaws becomes narrower farther down into the crusher. As the moveable jaw pushes against the stone in the chamber, the stone is fractured and reduced, moving down the chamber to the opening at the bottom.
The reduction ratio for a jaw crusher is typically 6-to-1, although it can be as high as 8-to-1. Jaw crushers can process shot rock and gravel. They can work with a range of stone from softer rock, such as limestone, to harder granite or basalt.
As the name implies, the horizontal-shaft impact (HSI) crusher has a shaft that runs horizontally through the crushing chamber, with a rotor that turns hammers or blow bars. It uses the high-speed impacting force of the turning blow bars hitting and throwing the stone to break the rock. It also uses the secondary force of the stone hitting the aprons (liners) in the chamber, as well as stone hitting stone.
With impact crushing, the stone breaks along its natural cleavage lines, resulting in a more cubical product, which is desirable for many of todays specifications. HSI crushers can be primary or secondary crushers. In the primary stage, HSIs are better suited for softer rock, such as limestone, and less abrasive stone. In the secondary stage, the HSI can process more abrasive and harder stone.
Cone crushers are similar to gyratory crushers in that they have a mantle that rotates within a bowl, but the chamber is not as steep. They are compression crushers that generally provide reduction ratios of 6-to-1 to 4-to-1. Cone crushers are used in secondary, tertiary and quaternary stages.
With proper choke-feed, cone-speed and reduction-ratio settings, cone crushers will efficiently produce material that is high quality and cubical in nature. In secondary stages, a standard-head cone is usually specified. A short-head cone is typically used in tertiary and quaternary stages. Cone crushers can crush stone of medium to very hard compressive strength as well as abrasive stone.
The vertical shaft impact crusher (or VSI) has a rotating shaft that runs vertically through the crushing chamber. In a standard configuration, the VSIs shaft is outfitted with wear-resistant shoes that catch and throw the feed stone against anvils that line the outside of the crushing chamber. The force of the impact, from the stone striking the shoes and anvils, fractures it along its natural fault lines.
VSIs also can be configured to use the rotor as a means of throwing the rock against other rock lining the outside of the chamber through centrifugal force. Known as autogenous crushing, the action of stone striking stone fractures the material. In shoe-and-anvil configurations, VSIs are suitable for medium to very hard stone that is not very abrasive. Autogenous VSIs are suitable for stone of any hardness and abrasion factor.
Roll crushers are a compression-type reduction crusher with a long history of success in a broad range of applications. The crushing chamber is formed by massive drums, revolving toward one another. The gap between the drums is adjustable, and the outer surface of the drum is composed of heavy manganese steel castings known as roll shells that are available with either a smooth or corrugated crushing surface.
Double roll crushers offer up to a 3-to-1 reduction ratio in some applications depending on the characteristics of the material. Triple roll crushers offer up to a 6-to-1 reduction. As a compressive crusher, the roll crusher is well suited for extremely hard and abrasive materials. Automatic welders are available to maintain the roll shell surface and minimize labor expense and wear costs.
These are rugged, dependable crushers, but not as productive as cone crushers with respect to volume. However, roll crushers provide very close product distribution and are excellent for chip stone, particularly when avoiding fines.
Hammermills are similar to impact crushers in the upper chamber where the hammer impacts the in-feed of material. The difference is that the rotor of a hammermill carries a number of swing type or pivoting hammers. Hammermills also incorporate a grate circle in the lower chamber of the crusher. Grates are available in a variety of configurations. The product must pass through the grate circle as it exits the machine, insuring controlled product sizing.
Hammermills crush or pulverize materials that have low abrasion. The rotor speed, hammer type and grate configuration can be converted for different applications. They can be used in a variety of applications, including primary and secondary reduction of aggregates, as well as numerous industrial applications.
Virgin or natural stone processing uses a multi-stage crushing and screening process for producing defined aggregate sizes from large lumps of rock. Such classified final fractions are used as aggregates for concrete, asphalt base, binder and surface course layers in road construction, as well as in building construction. The rock is quarried by means of drilling and blasting. There are then two options for processing the bulk material after it has been reduced to feeding size of the crushing plant: mobile or stationary plants.
When stone is processed in mobile primary crushing plants, excavators or wheel loaders feed the rock into the crusher that is set up at the quarry face, gravel pit or in a recycling yard or demolition site. The crushed material is then either sent to the secondary/tertiary processing stage via stacking conveyors or transported by trucks. Some mobile crushers have an independent secondary screen mounted on the unit, effectively replacing a standalone screen.
The higher the compressive strength of rock, the higher also is its quality, which plays an important role particularly in road construction. A materials compressive strength is delineated into hard, medium-hard or soft rock, which also determines the crushing techniques used for processing to obtain the desired particle sizes.
The materials quality is influenced significantly by particle shape. The more cubic-shaped the individual aggregate particles are, the better the resulting particle interlock. Final grains of pronounced cubic shape are achieved by using several crushing stages. A cubicity showing an edge ratio of better than 1-to-3 is typical of high-quality final aggregate.
As the earths natural resources are becoming ever more scarce, recycling is becoming ever more important. In the building industry, recycling and reuse of demolition concrete or reclaimed asphalt pavement help to reduce the requirements for primary raw materials. Mobile impact and jaw plants are uniquely positioned to produce high-quality reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA) for reuse in pavements, road bases, fill and foundations.
Use of RAP and RCA is growing dramatically as road agencies accept them more and more in their specs. But because RAP and RCA come from a variety of sources, to be specified for use by most departments of transportation they must be processed or fractionated and characterized into an engineered, value-added product. RCA or RAP are very commonly crushed and screened to usable sizes often by impact crushers and stored in blended stockpiles that can be characterized by lab testing for use in engineered applications.
Impact crushers are increasingly used for crushing recycling material. Impact crushers are capable of producing mineral aggregate mixes in one single crushing stage in a closed-cycle operation, making them particularly cost-effective. Different crusher units can alternatively be combined to process recycling material. A highly efficient method of processing recycling material combines crushing, screening and separation of metals. To produce an end product of even higher quality, the additional steps of washing to remove light materials such as plastics or paper by air classification and via electromagnetic metal separator are incorporated into the recycling process.
Mobile impact crushers with integrated secondary screens or without integrated screen used in conjunction with an independent mobile screen are ideal for producing large volumes of processed, fractionated RAP or RCA on a relatively small footprint in the plant. Mobile impactors are especially suited for RAP because they break up chunks of asphalt pavement or agglomerations of RAP, rather than downsize the aggregate gradation. Compression-type crushers such as jaws and cones can clog due to packing (caking) of RAP when the RAP is warm or wet.
Contaminants such as soil are part of processing demolition concrete. Mobile impact and jaw crushers when possessing integrated, independent prescreens removing dirt and fines before they ever enter the crushing circuit reduce equipment wear, save fuel, and with some customers, create a salable fill byproduct. A lined, heavy-duty vibrating feeder below the crusher can eliminate belt wear from rebar or dowel or tie bar damage. If present beneath the crusher, this deflector plate can keep tramp metal from degrading the conveyor belt. That way, the feeder below the crusher not the belt absorbs impact of rebar dropping through the crusher.
These mobile jaw and impact crushers may feature a diesel and electric-drive option. In this configuration, the crusher is directly diesel-driven, with the conveyor troughs, belts and prescreen electric-driven via power from the diesel generator. This concept not only reduces diesel fuel consumption, but also results in significantly reduced exhaust emissions and noise levels. This permits extremely efficient operation with low fuel consumption, allowing optimal loading of the crusher.
Jaw crushers operate according to the principle of pressure crushing. The raw feed is crushed in the wedge-shaped pit created between the fixed crusher jaw, and the crusher jaw articulated on an eccentric shaft. The feed material is crushed by the elliptic course of movement and transported downwards. This occurs until the material is smaller than the set crushing size.
Jaw crushers can be used in a wide range of applications. In the weight class up to 77 tons (70 metric tons), they can be used for both virgin stone and recycled concrete and asphalt aggregates processing as a classic primary crusher for natural stone with an active double-deck grizzly, or as a recycling crusher with vibrating discharge chute and the crusher outlet and magnetic separator.
Output for mobile jaw crushers ranges from 100 to 1,500 tph depending on the model size and consistency of the feed material. While larger mobile crushers produce more aggregate faster, transport weights and dimensions may limit how easily the crusher can be shipped long distances. Mobile jaw crushers can have either a vibratory feeder with integrated grizzly, or a vibrating feeder with an independent, double-deck, heavy-duty prescreen. Either way, wear in the system is reduced because medium and smaller gradations bypass the crusher, with an increase in end-product quality because a side-discharge conveyor removes fines. A bypass flap may provide easy diversion of the material flow, eliminating the need for a blind deck.
Jaw crusher units with extra-long, articulated crusher jaws prevent coarse material from blocking while moving all mounting elements of the crusher jaw from the wear area. A more even material flow may be affected if the transfer from the prescreen or the feeder trough is designed so material simply tilts into the crushing jaw.
Mobile jaw and impact crushers alike can be controlled by one operator using a handheld remote. The remote also can be used to move or relocate the crusher within a plant. In other words, the crusher can be run by one worker in the cab of an excavator or loader as he feeds material into the crusher. If he sees something deleterious going into the hopper, he can stop the crusher.
Impact crushing is totally different from pressure crushing. In impact crushing, feed material is picked up by a fast moving rotor, greatly accelerated and smashed against an impact plate (impact toggle). From there, it falls back within range of the rotor. The crushed material is broken again and again until it can pass through the gap between the rotor and impact toggle.
A correctly configured mobile jaw or impact crusher will enhance material flow through the plant and optimize productivity. New-design mobile jaw and impact crushers incorporate a highly efficient flow concept, which eliminates all restriction to the flow of the material throughout the entire plant. With this continuous-feed system, each step the material goes through in the plant is wider than the width of the one before it, eliminating choke or wear points.
For example, a grizzly feeder can be wider than the hopper, and the crusher inlet wider than the feeder. The discharge chute under the crusher is 4 inches wider than the inner width of the crusher, and the subsequent discharge belt is another 4 inches wider than the discharge chute. This configuration permits rapid flow of crushed material through the crusher. Also, performance can be significantly increased if the conveying frequencies of the feeder trough and the prescreen are adapted independently to the level of the crusher, permitting a more equal loading of the crushing area. This flow concept keeps a choke feed to the crusher, eliminating stops/starts of the feed system, which improves production, material shape and wear.
Users are focused on cost, the environment, availability, versatility and, above all, the quality of the end product. Simple crushing is a relatively easy process. But crushing material so that the particle size, distribution and cleanliness meet the high standards for concrete and asphalt requires effective primary screening, intelligent control for optimal loading, an adjustable crusher with high drive output, and a screening unit with oversize return feed.
This starts with continuous flow of material to the crusher through a variable-speed control feeder. Having hopper walls that hydraulically fold integrated into the chassis makes for quick erection of hopper sides on mobile units. If available, a fully independent prescreen for either jaw or impact models offers the ability to effectively prescreen material prior to crushing this allows for product to be sized prior to crushing, as opposed to using a conventional vibrating grizzly. This has the added value of increasing production, reducing wear costs and decreasing fuel consumption.
This independent double-deck vibrating screen affects primary screening of fines and contaminated material via a top-deck interchangeable punched sheet or grizzly, bottom-deck wire mesh or rubber blank. Discharged material might be conveyed either to the left or to the right for ease of positioning. The independent double-deck vibrating prescreen improves flow of material to the crusher, reducing blockages and feed surges.
Modern electrical systems will include effective guards against dust and moisture through double-protective housings, vibration isolation and an overpressure system in which higher air pressure in the electrical box keeps dust out. Simple and logical control of all functions via touch panel, simple error diagnostics by text indicator and remote maintenance system all are things to look for. For crushing demolition concrete, look for a high-performance electro- or permanent magnet with maximum discharge capacity, and hydraulic lifting and lowering function by means of radio remote control.
For impact crushers, a fully hydraulic crusher gap setting with automatic zero-point calculation can speed daily set-up. Featured only on certain mobile impact crushers, a fully hydraulic adjustment capability of the crushing gap permits greater plant uptime, while improving quality of end product.
Not only can the crushing gap be completely adjusted via the touch panel electronic control unit, but the zero point can be calculated while the rotor is running. This ability to accurately set the crusher aprons from the control panel with automatic detection of zero-point and target-value setting saves time, and improves the overall efficiency and handling of the crusher. On these mobile impact crushers, the zero point is the distance between the ledges of the rotor and the impact plates of the lower impact toggle, plus a defined safety distance. The desired crushing gap is approached from this zero point.
While the upper impact toggle is adjusted via simple hydraulic cylinders, the lower impact toggle has a hydraulic crushing gap adjustment device, which is secured electronically and mechanically against collision with the rotor. The crushing gap is set via the touch screen and approached hydraulically. Prior to setting of the crushing gap, the zero point is determined automatically.
For automatic zero-point determination with the rotor running, the impact toggle moves slowly onto the rotor ledges until it makes contact, which is detected by a sensor. The impact toggle then retracts to the defined safe distance. During this procedure, a stop ring slides on the piston rod. When the zero point is reached, the locking chamber is locked hydraulically and the stop ring is thus fixed in position. The stop ring now serves as a mechanical detent for the piston rod. During the stop ring check, which is carried out for every crusher restart, the saved zero point is compared to the actual value via the electronic limit switch. If the value deviates, a zero-point determination is carried out once again.
These impact crushers may feature a new inlet geometry that allows even better penetration of the material into the range of the rotor. Also, the wear behavior of the new C-form impact ledges has been improved to such an extent that the edges remain sharper longer, leading to improved material shape.
The machines come equipped with an efficient direct drive that improves performance. A latest-generation diesel engine transmits its power almost loss-free directly to the crushers flywheel, via a fluid coupling and V-belts. This drive concept enables versatility, as the rotor speed can be adjusted in four stages to suit different processing applications.
Secondary impact crushers and cone crushers are used to further process primary-crushed aggregate, and can be operated with or without attached screening units. These crushers can be used as either secondary or tertiary crushers depending on the application. When interlinked to other mobile units such as a primary or screen, complicated technical processing can be achieved.
Mobile cone crushers have been on the market for many years. These machines can be specially designed for secondary and tertiary crushing in hard-stone applications. They are extraordinarily efficient, diverse in application and very economical to use. To meet the diverse requirements in processing technology, mobile cone crushing plants are available in different sizes and configurations. Whether its a solo cone crusher, one used in addition to a triple-deck screen for closed-loop operation, or various-size cone crushers with a double-deck screen and oversize return conveyor, a suitable plant will be available for almost every task.
Mobile cone crushers may be available with or without integrated screen units. With the latter, an extremely efficient triple-deck screen unit may be used, which allows for closed-loop operation and produces three final products. Here the screen areas must be large so material quantities can be screened efficiently and ensure that the cone crusher always has the correct fill level, which is particularly important for the quality of the end product.
Mobile, tracked crushers and screen plants are advancing into output ranges that were recently only possible using stationary plants. Previously, only stationary plants were used for complicated aggregate processing applications. But thanks to the advancements made in machine technology, it is becoming increasingly possible to employ mobile technology for traditional stationary applications.
Mobile crushers are used in quarries, in mining, on jobsites, and in the recycling industry. These plants are mounted on crawler tracks and can process rock and recycling material, producing mineral aggregate and recycled building materials respectively for the construction industry. A major advantage of mobile crushers is their flexibility to move from one location to the next. They are suitable for transport, but can also cover short distances within the boundaries of their operating site, whether in a quarry or on the jobsite. When operating in quarries, they usually follow the quarry face, processing the stone directly on site.
For transport over long distances to a new location or different quarry, mobile crushers are loaded on low trailers. No more than 20 minutes to an hour is needed for setting the plant up for operation. Their flexibility enables the mobile crushers to process even small quantities of material with economic efficiency.
Mobile plants allow the combination of prescreening that prepares the rock for the crushing process and grading, which precisely separates defined aggregate particle sizes into different end products to be integrated with the crushing unit into one single machine. In the first stage, the material is screened using an active prescreen. After prescreening, it is transferred to the crusher, from where it is either stockpiled via a discharge conveyor or forwarded to a final screen or a secondary crushing stage. Depending on the specified end product, particles are then either graded by screening units or transported to additional crushing stages by secondary or tertiary impact crushers or cone crushers. Further downstream screening units are used for grading the final aggregate fractions.
The process of prescreening, crushing and grading is a common operation in mobile materials processing and can be varied in a number of ways. Mobile crushers with up to three crushing stages are increasingly used in modern quarries. Different mobile crushing and screening plants can be combined for managing more complex crushing and screening jobs that would previously have required a stationary crushing and screening plant.
Interlinked mobile plants incorporate crushers and screens that work in conjunction with each other, and are coordinated in terms of performance and function. Mining permits are under time constraints and mobile plants provide faster setup times. They provide better resale value and reusability, as mobile plants can also be used individually. They also reduce operating costs in terms of fewer haul trucks and less personnel.
With a so-equipped mobile crusher, the feed operator can shut the machine down or change the size of the material, all using the remote control, or use it to walk the crusher from one part of the site to the other, or onto a flat bed trailer for relocation to a different quarry or recycling yard. This reduces personnel and hauling costs compared to a stationary plant. With the mobile jaw or impact primary crusher, the only additional personnel needed would be a skid-steer operator to remove scrap steel, and someone to move the stockpiles.
Thanks to better technology, mobile plants can achieve final aggregate fractions, which previously only were possible with stationary plants. Production availability is on par with stationary plants. Theyre applicable in all quarries, but can be used for small deposits if the owner has several quarries or various operation sites. For example, an operator of several stone quarries can use the plants in changing market situations at different excavation sites. In addition, they also can be used as individual machines. A further factor is that mobile plants, in general, require simpler and shorter licensing procedures.
The high cost of labor keeps going up. A stationary crusher might be able to produce multiple times the amount of product, but also would require about seven or eight workers. Aggregate producers can benefit when producing material with the minimized crew used for mobile jaw and impact crushers.
Using correct maintenance practices, mobile crushers will remain dependable throughout their working life. Crushing and processing material can result in excessive wear on certain components, excessive vibration throughout the plant, and excessive dust in the working environment. Some applications are more aggressive than others. A hard rock application is going to require more maintenance on top of standard maintenance, as there will be more vibration, more dust and more wear than from a softer aggregate.
Due to the nature of its purpose, from the moment a mobile crusher starts, the machine is wearing itself out and breaking itself down. Without routine, regular maintenance and repair, a mobile crusher will not be reliable nor provide the material customers demand.
The first area of wear on any machine is the feed system. Whether its a feeder with an integrated grizzly, or a feeder with an independent prescreen, how the machine is fed contributes to wear. When setting up and maintaining a machine, the machine must be level. A machine that is unlevel left to right will experience increased wear on all components, including the feeder, the screens, the crushing chambers and the conveyor belts. In addition, it reduces production and screening efficiency, as the whole area of the machine is not being effectively used. Also, having the machine sit high at the discharge end will have the effect of feeding the material uphill in the feeder and reducing its efficiency, thus reducing production.
Another area for consideration is the equipment used to feed the machine. The operator using a loader to feed the crusher will have no control over the feed size, as he cannot see whats in the bucket. Whereas with an excavator, the operator can see whats inside and has more control over the feed into the hopper. That is, the operator is not feeding so much material all at once and is controlling the size of the feed. This reduces wear in the feed hoppers impact zones and eliminates material blockages due to feed size being too large to enter the chamber.
Dust is a problem in its own right, especially for the power plant of the mobile crusher. In a very dusty application, it is easy to plug the radiator and have engine-overheating problems. High dust levels cause increased maintenance intervals on air filters, and if not controlled properly, can enter the diesel tank and cause problems with the fuel system. Also, dust that gets inside the crusher increases wear. But if systems are put in place to remove the dust, it should keep it from going into the machine in the first place.
Dust also is a hazard on walkways and a problem for conveyors. If maintained, side-skirting and sealing the conveyors keeps dust from spilling out, building up underneath the conveyor, or building up in rollers, pulleys, bearings, and causing wear on shafts. Its important to maintain the sealing rubbers on the conveyor belts to avoid those issues. Routine maintenance calls for removing accumulated dust from inside and under the machine.
Dust also is a problem for circuit boards and programmable controllers. Dust causes electrical switches to malfunction because it stops the contacts from correctly seating. Electrical systems under positive air pressure dont permit dust to penetrate the control system. In control panels with a correctly maintained positive pressure system, filters remove dust from air that is being pumped into the cabinets. If the filters are plugged, the system will not pull as much air through, allowing dust, moisture and heat to build in the cabinet.
There are also impact aprons against which the rock is thrown, which also see high wear. There are side plates or wear sheets on the sides of the machine. The highest wear area is around the impact crusher itself, around the circumference of the rotor. If not maintained, the wear items will wear through and compromise the structure of the crusher box.
Conduct a daily visual check of the machine. The jaw is simple; just stand up on the walkway and take a look down inside. A crushers jaw plate can be flipped so there are two sides of wear on them. Once half the jaw is worn out, flip it; once that side is worn, change it.
The impact crusher will have an inspection hatch to see inside. Check to see how much material is left on the blow bars and how much is left on the wear sheets on the side of the crusher box. If half the bar is worn out after one week, change the blow bars in another week.The frequency of changes depends entirely on the application and the rock that is being crushed.
They have to be user serviceable, user friendly, and able to be changed in a short time. The best way to change these parts is a service truck with a crane; some use excavators but thats not recommended by any means.
After initial blasting, breakers are used to break down aggregate that typically is not only too large to be hauled in dump trucks, but also too large for crushers that size rock to meet asphalt, drainage system, concrete and landscaping specifications. Breakers can be mounted to a mobile carrier, such as an excavator, or to stationary boom systems that can be attached to a crusher. The total number of hydraulic breakers can vary from site to site depending on production levels, the type of aggregate materials and the entire scope of the operation.
Without hydraulic breakers, workers rely on alternative practices that can quickly affect production rates. For instance, blasting mandates shutting down operations and moving workers to a safe location. And when you consider how many times oversize aggregate might need to be reduced, this can lead to a significant amount of downtime and substantially lower production rates.
Aggregate operations can use hydraulic breakers to attack oversize without having to clear the quarry. But with an ever-growing variety of manufacturers, sizes and models to choose from, narrowing the decision to one hydraulic breaker can be overwhelming with all of the stats and speculation. Thats why its important to know what factors to consider before investing in a new hydraulic breaker.
In most cases, heavy equipment dealers are very knowledgeable about quarry equipment, including breakers, so they are a good resource for finding the best model for a carrier, usually an excavator or stationary boom system. More than likely, they will have specifications and information about various breaker sizes to help gauge what model is best. But being familiar with what to look for in a breaker can streamline the selection process.
The best places to look for breaker information are in the manufacturers brochure, website, owners manual or catalogue. First, carefully review the carrier weight ranges. A breaker that is too big for the carrier can create unsafe working conditions and cause excessive wear to the carrier. An oversized breaker also transmits energy in two directions, toward the aggregate and through the equipment. This produces wasted energy and can damage the carrier. But using a breaker thats too small puts excessive force on the tool steel, which transmits percussive energy from the breaker to the material. Using breakers that are too small also can damage mounting adapters and internal components, which considerably decreases their life.
Once you find a breaker that meets the carriers capacity, check its output power, which is typically measured in foot-pounds. Foot-pound classes are generalizations and are not based on any physical test. Often the breakers output will be documented in one of two ways: as the manufacturers calculated foot-pound class or as an Association of Equipment Manufacturers measured foot-pound rating. Foot-pound class ratings can be deceiving since they are loosely based on the breakers service weight and not the result of any physical test. The AEM rating, on the other hand, measures the force a breaker exerts in a single blow through repeatable and certified testing methods. The AEM rating, which was developed by the Mounted Breaker Manufacturers Bureau, makes it easier to compare breaker models by reviewing true figures collected during an actual test procedure.
For instance, three breaker manufacturers might claim their breakers belong in a 1,000-lb. breaker class. But AEM testing standards could reveal all three actually have less foot-pound impact. You can tell if a breaker has been AEM tested if a manufacturer provides a disclosure statement or if the breaker is labeled with an AEM Tool Energy seal. If you cannot find this information, contact the manufacturer. In addition to output energy specifications, manufacturers often supply estimates for production rates on different types of aggregate material. Make sure to get the right measurements to make the best decision.
In addition to weight and output power, look at the breakers mounting package. Two things are crucial for mounting a breaker to a carrier: a hydraulic installation kit and mounting components. Breakers need hydraulic plumbing with unidirectional flow to move oil from the carrier to the breaker and back again. A one-way flow hydraulic kit is sufficient to power the breaker as long as the components are sized to properly handle the required flows and pressures. But, consider a bidirectional flow hydraulic kit if you plan to use the same carrier with other attachments that require two-way flow. Check with the dealer or breaker manufacturer to determine which hydraulic package best fits current and future needs.
Hydraulic flow and pressure specifications also need to be considered when pairing a breaker to a hydraulic system. If the carrier cannot provide enough flow at the right pressure, the breaker wont perform with maximum output, which lowers productivity and can damage the breaker. Additionally, a breaker receiving too much flow can wear quickly, which reduces its service life. For the best results, follow the hydraulic breaker specifications found in owners manuals, catalogs and brochures. Youll find out if a breaker has additional systems that might require additional servicing. For instance, some breakers feature nitrogen gas-assist systems that work with the hydraulic oil to accelerate the breakers piston. The nitrogen systems specifications need to be followed for consistent breaker power output.
Brackets or pin and bushing kits are commonly required to attach the breaker to the carrier. Typically they are bolted to the top of a breaker and are configured to match a specific carrier. Some manufacturers make universal mounting brackets that can accommodate two or three different sizes of carriers. With the adjustable pins, bushings or other components inside these universal brackets, the breaker can fit a range of carriers. However, varying distances between pin centers can complicate hookups to quick coupling systems. In addition, loose components, such as spacers, can become lost when the breaker is not in use and detached from the carrier.
Some carriers are equipped with quick-coupling systems, which require a breakers mounting interface to be configured like the carriers original attachment. Some manufacturers produce top-mount brackets that pair extremely well with couplers. This allows an operator to use the original bucket pins from the carrier to attach the breaker, and eliminates the need for new pins. This pairing also ensures a fast pickup with the quick coupler.
Its also a good idea to check which breaker tools are available through the dealer and manufacturer. The most common for aggregate mining are chisels and blunts. There are two kinds of chisels commonly used in aggregate mines: crosscut and inline. Both chisels resemble a flat head screwdriver, but the crosscut chisels are used when carrier operators want to direct force in a left-to-right concentration; whereas, inline chisels direct force fore and aft. With chisel tools, operators can concentrate a breakers energy to develop cracks, break open seams or define scribe lines.
If a chisel cant access or develop a crack or seam, a blunt can be used. Blunts have a flattened head that spreads the energy equally in all directions. This creates a shattering effect that promotes cracks and seam separation. Ask your dealer if the tools you are considering are suited for the application. Using non-original equipment manufacturer tool steel can damage the percussive piston in the breaker, seize into the wear bushings, or cause excessive wear.
Regular breaker maintenance is necessary, yet its one of the biggest challenges for aggregate operations. It not only extends the life of the breaker, but also can keep minor inconveniences from turning into expensive problems. Some manufacturers recommend operators inspect breakers daily to check grease levels and make sure there are no worn or damaged parts or hydraulic leaks.
Breakers need to be lubricated with adequate amounts of grease to keep the tool bushing area clear and reduce friction, but follow the manufacturers recommendations. For example, adding grease before properly positioning the breaker can lead to seal damage or even catastrophic failure. And too little grease could cause the bushings to overheat, seize and damage tools. Also, manufacturers advise using high-moly grease that withstands working temperatures greater than 500 degrees. Some breakers have automatic lube systems that manage grease levels, but those systems still need inspections to ensure there is adequate grease in their vessels. Shiny marks on the tool are a good indication the breaker is not properly lubricated.
Little has changed in basic crusher design over past decades, other than that of improvements in speed and chamber design. Rebuilding and keeping the same crusher in operation year after year has long been the typical approach. However, recent developments have brought about the advent of new hydraulic systems in modern crusher designs innovations stimulated by the need for greater productivity as well as a safer working environment. Importantly, the hydraulic systems in modern crusher designs are engineered to deliver greater plant uptime and eliminate the safety risks associated with manual intervention.
Indeed the crushing arena is a hazardous environment. Large material and debris can jam inside the crusher, damaging components and causing costly downtime. Importantly, manually digging out the crusher before repairs or restarts puts workers in extremely dangerous positions.
The Mine Safety and Health Administration has reported numerous injuries and fatalities incurred when climbing in or under the jaw to manually clear, repair or adjust the typical older-style jaw crusher. Consider that fatalities and injuries can occur even when the machine is locked out and tagged out. Recent examples include a foreman injured while attempting to dislodge a piece of steel caught in the primary jaw crusher. Another incident involved a fatality when a maintenance man was removing the toggle plate seat from the pitman on a jaw crusher. The worker was standing on a temporary platform when the bolts holding the toggle seat were removed, causing the pitman to move and strike him.
The hydraulic systems on modern crusher designs eliminate the need for workers to place themselves in or under the crusher. An overview of hydraulic system technology points to these three key elements:
A hydraulic chamber-clearing system that automatically opens the crusher to a safe position, allowing materials to pass. A hydraulic overload relief that protects parts and components against overload damage. A hydraulic adjustment that eliminates the maintenance downtime associated with manual crusher adjustments, and maintains safe, consistent crusher output without the need for worker intervention.
Whether a crusher is jammed by large material, tramp iron or uncrushable debris; or is stalled by a power failure the chamber must be cleared before restarting. Manual clearing is a lengthy and risky task, especially since material can be wedged inside the crusher with tremendous pressure, and dislodging poses much danger to workers placed in harms way inside the crusher.
Unlike that of the older-style jaw, the modern jaw will clear itself automatically with hydraulics that open the crusher to a safe position, and allow materials to pass again, without the need for manual intervention. If a feeder or deflector plate is installed under the crusher, uncrushable material will transfer smoothly onto the conveyor without slicing the belt.
To prevent crusher damage, downtime and difficult maintenance procedures, the hydraulic overload relief system opens the crusher when internal forces become too high, protecting the unit against costly component failure. After relief, the system automatically returns the crusher to the previous setting for continued crushing.
The modern crusher is engineered with oversized hydraulic cylinders and a traveling toggle beam to achieve reliable overload protection and simple crusher adjustment. All closed-side setting adjustments are made with push-button controls, with no shims being needed at any time (to shim is the act of inserting a timber or other materials under equipment). This is a key development as many accidents and injuries have occurred during shim adjustment, a process which has no less than 15 steps as described in the primary crusher shim adjustment training program offered by MSHA.
According to leading aggregate producers, repairs and maintenance labor average 30 to 35 percent of direct operating costs, says Erik Schmidt, ResourceDevelopment Manager, Johnson Crushers International, Inc. Thats a pretty large factor towards the overhead of that equipment.
There are three approaches to maintenance: reactive, preventative and predictive. Reactive is repairing something that has failed. Preventative maintenance is often viewed as unnecessary but minimizes downtime because the machine is getting repaired before failure. Predictive means using historical service life data to determine when a machine will likely breakdown and then taking the necessary steps to address the problem before failure occurs.
According to Schmidt: 75 percent of companies are operating in the run until its broke mentality. Maintenance is sacrificed. As a result of that, the costs are high when you have unplanned down time due to equipment failure, he says. It can lead to loss of production, ancillary or consequential damages, expedited freight costs for parts, loss of production, and even low morale.
According to Schmidt, daily visual inspections will catch a vast majority of impending failures that could be costing operations in unnecessary and preventable down time. That is why it is number one on my list of tips for crusher maintenance, says Schmidt.
The lack of daily inspections is going on a lot more than people would like to admit, says Schmidt. If you get into the crushing chamber every day and look for blockage, material build up and wear, you can prevent failures from occurring by identifying future problems today. And, if you are operating in really wet, sticky, or clay material, you might find that you need to get in there more than once a day.
Visual inspections are crucial. In the scenario where the conveyor underneath a cone crusher stalls, the material will build up inside the crushing chamber and eventually stall the crusher. Material can stay stuck inside that cannot be seen.
No one crawls inside there to see that it is still blocked inside the cone, says Schmit. Then, once they get the discharge conveyor going again, they start the crusher. Thats the absolute wrong thing to do. Lock out and tag out, then get in there and look, because material can easily block off chambers, causing excessive wear and even sub-sequential damage to the anti-spin mechanism or related internal components.
In cone crushers, one common form of abuse is bowl float. Also called ring bounce or upper frame movement. It is the machines relief system that is designed to allow uncrushables to pass through the machine, but if youre continually overcoming relief pressures due to the application, that is going to cause damage at the seat and other internal components. Its a sign of abuse and the end result is expensive down time and repairs, says Schmidt.
To avoid bowl float, Schmidt recommends you check the feed material going into the crusher but keep the crusher choke fed. You might have too many fines going into the crusher, which means you have a screening problemnot a crushing problem, he says. Also, you want to choke feed the crusher to get maximum production rates and a 360-degree crush. Dont trickle feed the crusher; that will lead to uneven component wear, more irregular product sizes and less production. An inexperienced operator will often reduce the feed rate rather than to simply open the close side setting.
For HSI, Schmidt recommends providing well-graded input feed to the crusher, because this will maximize production while minimizing costs, and to properly prep the feed when crushing recycled concrete with steel, because this will reduce plugging in the chamber and blow bar breakage. Failure to take certain precautions when using equipment is abusive.
Always use the fluids prescribed by the manufacturer and check with their guidelines if you plan on using something other than what is specified. Be careful when changing viscosities of oil. Doing so will also change the extreme pressure (EP) rating of the oil, and may not perform the same in your machine, says Schmidt.
Contaminants such as dirt and water can also get into fuel, either while in storage or when filling the machine. Gone are the days of the open bucket, says Schmidt. Now, all fluids need to be kept clean, and a lot more caution is taken to avoid contamination.
Tier 3 and Tier 4 engines use a high-pressure injection system and, if any dirt gets into the system, and youve wiped it out. You will end up replacing the machines injection pumps and possibly all other fuel-rail components in the system, says Schmidt.
According to Schmidt, misapplication leads to a lot of repairs and failures. Look at whats going in and what youre expecting out of it. What is the top-sized feed material going into the machine and the machines closed side setting? That gives you the machines reduction ratio, explains Schmidt.
If you exceed what an HSI or cone crusher is designed to do within its configuration, you can expect to decrease the lifespan of certain components, because you are putting stresses on parts of the machine that werent designed to bear that stress.
Misapplication can lead to uneven liner wear. If the crusher is wearing low in the chamber or high in the chamber, you are going to get pockets or a hook, and its going to cause overload, either high amp draw or bowl floating. This will have a negative effect on performance and cause long-term damage to componentry.
Knowing a machines normal or average operating conditions is integral to monitoringmachine health. After all, you cant know when a machine is working outside of normal or average operating conditions unless you know what those conditions are.
If you keep a log book, long-term operating performance data will create a trend and any data that is an outlier to that trend could be an indicator that something is wrong, says Schmidt. You may be able to predict when a machine is going to fail.
Once you have logged enough data, you will be able to see trends in the data. Once you become aware of the trends, actions can be taken to make sure they dont create unplanned down time. What is your machines coast down times? asks Schmidt. How long does it take before the crusher comes to a stop after you push the stop button? Normally, it takes 72 seconds, for example; today it took 20 seconds. Whats that telling you?
By monitoring these and other potential indicators of machine health, you can identify problems earlier, before the equipment fails while in production, and the servicing can be scheduled for a time that will cost you little downtime. Benchmarking is key in executing predictive maintenance.
(select country) United States Afghanistan land Islands Albania Algeria American Samoa Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia Bonaire Bosnia and Herzegovina Botswana British Indian Ocean Territory Brazil Brunei Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos Islands Colombia Comoros Congo Cook Islands Costa Rica Croatia Cuba Curaao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guam Guatemala Guernsey Guinea Guinea - Bissau Guyana Haiti Heard Island Honduras Hong Kong Hungary Iceland India Indonesia Iran Iraq Ireland Isle of Man Israel Italy Ivory Coast Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati North Korea South Korea Kosovo Kuwait Kyrgyzstan Laos Latvia Lebanon Lesotho Liberia Libya Liechtenstein Lithuania Luxembourg Macau Macedonia Madagascar Malawi Malaysia Maldives Mali Malta Marshall Islands Martinique Mauritania Mauritius Mayotte Mexico Micronesia Moldova Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Northern Marianas Norway Oman Pakistan Palau Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Puerto Rico Qatar Romania Russia Rwanda Runion Saint Barthelemy Saint Helena Saint Kitts and Nevis Saint Lucia Saint Martin (French) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa Saint Pierre and Miquelon San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard Swaziland Sweden Switzerland Syria Taiwan Tajikistan Tanzania Thailand Timor - Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Minor Outlying Islands Uruguay Uzbekistan Vanuatu Vatican City Venezuela Vietnam British Virgin Islands US Virgin Islands Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe