what is a hydraulic cone crusher? - hongxing machinery
When the cone crusher works, the rotation of the motor is performed by a pulley or coupling, the cone crusher transmission shaft and the crusher cone under the force of an eccentric sleeve to make a swing motion around a fixed point. Therefore, the crushing wall of the crushing cone is sometimes close to and sometimes away from the surface of the mortar wall fixed on the adjusting sleeve, so that the ore is continuously impacted, crushed and bent in the crushing cavity to achieve the ore crushing.
The motor drives the eccentric sleeve to rotate through the bevel gear to make the crushing cone rotate, which accomplishes the crushing work when the crushing cone is sometimes near and away from the fixed cone.
The connection between the support sleeve and the frame is compressed by a spring so that when an unbreakable object such as a metal block falls into the crusher, the spring will compress and deform to evacuate these objects and achieve insurance to prevent the machine from damaging.
If the foreign matter is stuck in the ore discharge, it can be solved by expanding the discharging port and then the cone crusher is automatically reset by the spring to resume normal work.
This hydraulic system controls the movement of 3 basic circuits. One is the action of the fixed cone hydraulic locking hydraulic cylinder, the second is the hydraulic motor that adjusts the gap between the moving and fixed cone. The third is the way of the hydraulic cylinder when the iron is released and cleaned.
The lock cylinder is installed between the lock ring and the adjustment ring. It can support the lock ring located on the upper part of the adjustment ring to ensure that the fixed cone is located in the broken position in the adjustment ring when the hydraulic cylinder is pressurized during the crushing process.
When the gap between the moving and fixed cones needs to be adjusted, the pressure of the locking hydraulic cylinder is released, and the motor on the adjusting ring starts to start. The gear on the motor engages the driving ring with the adjusting cap to realize the automatic adjustment.
The iron release cylinder is connected to the lower part of the mainframe and is fixed with the adopt to overcome the normal braking force. Abnormal operation or excessive crushing force generated by the foreign object as it passes through the crusher cause the adjustment ring to rise. Once the overload disappears or iron passes through the crusher, the crusher returns to normal. Besides, to clean the crusher, the adjustment ring needs to be removed from the mainframe.
This hydraulic system uses a fixed displacement plunger pump as the power source, that is to say, it converts the mechanical energy supplied by the prime mover into the pressure energy of the working medium (hydraulic oil). During this period, each hydraulic valve controls and regulates the pressure, flow, and direction, to ensure that the execution part (each hydraulic cylinder and motor) to complete the predetermined law of movement. The maximum pressure of the electromagnetic relief valve adjustment system in this circuit is 20MPa.
The locking circuit is controlled by accumulator pressure and zero leakage solenoid valve. Because the lock cylinder is always in a pressure-maintaining state during the working process, the use of an accumulator to maintain pressure can prevent the plunger pump from starting and stopping frequently. The locking cylinder is a plunger cylinder so that the zero-leakage solenoid valve is reset by the weight of the support part after the pressure is released.
Adjust the motor circuit by using a shuttle valve to control the motor running and stopping. Due to the working nature of the host, the motor needs to have a brake function. Therefore, the shuttle valve is used to control the brake of the motor. Thus, the motor can realize the function of oil-braking and oil-cut braking.
Accumulators are used to absorbing shocks in the iron release and cleaning circuits. Due to abnormal operation or excessive crushing force generated by the crusher when the main machine is working, the adjustment ring rises upward. When the adjustment ring rises, the hydraulic oil in the upper cavity of the hydraulic cylinder will be squeezed into the accumulator, then the nitrogen in the accumulator is compressed.
After that, the compressed nitrogen forces the hydraulic oil to return to the hydraulic cylinder, and the piston rod of the hydraulic cylinder is retracted, and the adjustment ring is returned to the original position. This circuit uses an accumulator to absorb shocks easily, easily and reliably.
The most common types of hydraulic cone crushers are single-cylinder cone crusher, multi-cylinder cone crusher, and fully hydraulic crusher.SCseries single-cylinder hydraulic cone crusher is developed with advanced crushing technology, integrating mechanical, hydraulic, electrical, intelligent control, etc.Thesingle-cylinder hydraulic cone crusherhas a new crusher structure, optimized laminated crushing cavity type, and a fully intelligent automation control system. In general, itcan be widely used in medium crushing, fine crushing, and ultra-fine crushing operations.
Multi-cylinder hydraulic cone crusher is suitable for crushing various ores and rocks with medium or higher hardness, such as limestone, iron ore, cobblestone, non-ferrous metal oreand so on.Its high speed, high crushing capacity, and unique patented design make the crushed finished producta high-quality cube shape, and the easy maintenance feature can ensure its high stability operation.
The full-hydraulic cone crusher is a new cone crusher that combines advanced multi-cylinder hydraulic cone crusher and PSG cone crusher. This machineadopts advanced design concepts and is optimized and designed. The fine-grained content in the crushed product is higher, and the content of the granules smaller than the closed-side discharge can reach 80%, which can significantly improve the processing capacity of subsequent processes and reduce comprehensive energy consumption.
The successful combination of high-performance crushing cavity type and high crushing frequency has greatly improved the processing capacity of the machine. Due to the principle of lamination crushing, the crushed products are mostly cubic structures, which greatly reduces needle-shaped materials.
symons cone crusher
For finer crushing or reduction a Symonscone crusher the norm. Symons are commonly used for secondary, tertiary or quaternary crushing. They do this by a different chamber design which is flatter and by operating at about twice the rotational speed of a primary type gyratory crusher.
One of the first cone crushers had a direct drive vertical motor mounted above the spider with the drive shaft passing through the hollow bored main shaft. With relatively high speeds of 480 to 580 rpm and small eccentric throw, the machine produced a uniform produce with minimum fines.There are numerous Symonscone crusher manufacturers of modern crushers each promoting some unique aspect.
The Allis Chalmers Hydrocone selling point is its adjustability and tramp protection through a hydraulic support system for the headcentre. By merely adjusting the oil reservoir below the head centre the crusher setting can be changed while in full operation. Tramp metal causes a surge of pressure in this hydraulic system which is absorbed through relief valves and gas-bladder-filled accumulator bottles which allow the headcentre to momentarily drop and return to its normal operating position when the tramp has fallen through.
The Symons or Rexnord spring cone crusher is adjusted by spinning the bowl up or down manually or through hydraulic rams. A series of powerful springs give the necessary tramp protection. Several other manufacturers produce similar types and sizes of crushers but all follow the basic types described.
When the Symons brothers Invented the cone crusher, they employed the principle wherein the length of the crushing stroke was related to the free fall of material by gravity. This permitted the material being crushed to fall vertically in the crushing chamber; and in effect, caused the particles to be crushed in a series of steps or stages as the particles got smaller due to the crushing action. This also helps to reduce the rate of wear of the liners since the sliding motion of the particles is minimized.
Recognizing that the Symons principle of crushing is the most efficient means of ore and aggregate reduction in hard rock applications, the engineers used this same principle in the design on the hydrocone.
Versatility in the form of having the ability to perform in a wide range of applications without the need for a change in major assemblies was another objective in the design. Ease of maintenance and remote setting capability also were part of the design parameters the market requires.
There is no startling revelation to the fact that the mining industry as a whole is generally moving toward the use of larger equipment to process ores in quantities far greater than what was even considered a decade ago. Trucks and shovels have led the way in extra large machines and many other manufacturers have followed suit in the development of so-called supers in their line of equipment.
In order to keep pace with the industry, crusher manufacturers have also enlarged the size of their equipment. There is now on the market, a Gyratory crusher capable of accepting a 72 diameter piece of ore. Primary jaw crushers have also increased in size. It is inevitable, therefore, that larger secondary cone crushers would also be required to complement the other equipment used to process these large quantities of ore. This super-size secondary cone crusher is the SYMONS 10 Ft. Cone Crusher.
Until 1973, the largest cone crusher built was the 7 Ft. Extra Heavy Duty crusher, which is currently used in the majority of the mining operations throughout the world. The 10 Ft. crusher, when compared to the 7 Ft. Extra Heavy Duty Crusher, is approximately 1 times larger in physical dimensions; three times heavier; will accept a maximum feed size which is approximately twice as large; and will crush at approximately 2 times the rate of the 7 Ft. machine at identical closed side settings. It will be the largest cone crusher built in the world.
The conclusions of this investigation were all positive the crusher could be built and at a cost that would be in line with its size and capacity and also with other size crushers. After that preliminary study, the project became dormant for several years.
The project was reactivated and this time general assembly drawings were made which incorporated many improvements in the crusher such as pneumatic cylinders in place of the conventional, springs for tramp iron release, a two-piece main frame a dynamically balanced design of the internal moving parts of the crusher, and an automatic clearing and adjusting mechanism for the crusher. At this stage of development we felt we were ready to build a 10 Ft. crusher for any mine that was willing to try one. Unfortunately, the conservative posture of the mining industry did not exactly coincide with our sales plans. This, added to the popularity of the autogenous mill concept at the time, led to another lull in the 10 Ft. development program.
The project was reactivated again in 1970, this time primarily at the request of one of the large Minnesota Iron Range mining companies. We then undertook a comprehensive market research study to determine if there was a need for this size crusher by the mining industry in general, rather than just the iron ore industry. We talked not only to the iron ore people but to the copper people and persons connected with the other metallic ores as well. The acceptability of this large crusher was also discussed with the aggregate industry. After interviews with many of the major mining companies, the decision was made to complete the entire engineering phase of the development program and to actively solicit a customer for this new crusher. We spent approximately $85,000 on engineering work and tests on the gamble that we could find a customer. I speak of a gamble because during our market research study we continually were told my company would be very interested in buying a 10 Ft. crusher, but only after we have seen one in operation.
The actual building and test of the first prototype unit without a firm commitment for a sale was an economic impossibility. We were now at the point where we needed to sell at least one unit in order to prove not only the mechanical reliability of the machine, but the economic justification for its purchase as well. Needless to say, when the order for two SYMONS 10 Ft. cone crushers was received, we felt we were now on the way toward completion of the development program.
Perhaps at this point it might be apropos to examine the crusher itself. It will stand 15-6 above its foundation, the overall height will be 19-4-. At its greatest diameter, in the area of the adjustment ring, it will be approximately 17-6. It will weigh approximately 550,000 lbs. Under normal crushing conditions, the crusher will be connected to a 700 HP motor. A 50 ton. overhead crane is required to perform routine maintenance on this crusher.
The main shaft assembly will weigh approximately 92,000 lbs. and the bowl assembly approximately 95,000 lbs. The mantle and bowl liner, cast from manganese steel, will weigh approximately 13,000 lbs. and 25,000 lbs. respectively.
The throughput capacity of the Standard will be approximately 1300 TPH at a 1 closed side setting and 3000 TPH at a 2- closed side setting. The throughput capacity of the SHORT HEAD will be approximately 800 TPH at closed side setting and 1450 TPH at a 9/16 closed side setting.
Persons familiar with the design of a conventional 7 Ft. SYMONS cone crusher will recognize that the design of the 10 Ft. is quite similar to it. As a matter of fact, we like to say that the design of the 10 Ft. is evolutionary rather than revolutionary, because all the reliable features of the SYMONS cone crusher were retained and the only changes that were made were those that added to the convenience of the operator, such as automatic clearing and automatic adjustment. From a mechanical point of view the stresses generated due to crushing loads are less in the 10 Ft. crusher than in the existing 7 Ft. Extra Heavy Duty cone.
One of our senior engineers who has long since retired told me that he had the occasion many years ago to make a presentation of a newly designed crusher to a prospective customer. He carefully prepared a rather detailed description of the crusher which included all the features that his new machine had when compared to the customers existing machine. The presentation itself took about one hour and after that period the customer leaned back in his chair and said, Thats all well and good, but will it crush rock? In effect, the customer was; saying that all the features in the world were of no use to him if the crusher did not perform its basic function to crush rock and ultimately make profits for the owner. Using todays financial terminology he was asking the engineer to economically cost justify the purchase of the crusher.
The working day of the contemporary manager or project engineer evolves around making decisions to economically justify a piece of equipment or a new operation. In our development program of the 10 Ft. cone crusher, we felt that the economic justification, from the customers point of view, was just as important to develop as the engineering aspects of the program. So we developed a three-part program to examine the economics of installing a 10 Ft. crusher. First we talked in wide generalities concerning the use of a 10 Ft. crusher. Secondly, we discussed the ramifications of using a 10 Ft. crusher versus 7 Ft. crushers in a completely new plant being considered for the future. Thirdly, we examined how a 10 Ft. crusher could be used to its best advantage in a plant that is being expanded.
The first consideration was the economic generalities of installing the crusher, or more specifically, what questions regarding the installation are pertinent to every crushing plant. Usually, the initial comparison which is made between a 7 Ft. crusher and a 10 Ft. crusher is that of price versus capacity. Theoretically, the capacity of a 10 Ft. crusher is 2 times that of a 7 Ft. while the selling price is approximately 3 times that of the 7 Ft. On that basis alone, it would appear that the 10 Ft. could not be justified. However, this is an incomplete picture. Recent cost estimates show that considerable savings are realized when the entire physical plant structure is considered. Because fewer machines are required to crush an equivalent amount of ore, the size of the buildings can be reduced, thereby decreasing the capital investment of buildings and allied equipment used as auxiliaries for the crusher.
Total manpower requirements to operate and maintain the plant is another of the generalities which were considered. Fewer crushers normally require less personnel to operate and perform maintenance, Manpower requirements obviously play a large part in the profitability of a plant. Therefore, it follows that using a 10 Ft. in place of multiple 7 Ft. units should be more profitable from the standpoint of manpower. We should, however, clarify one point regarding normal maintenance of the 10 Ft. crusher which is commonly misunderstood; namely, the periodic changeout of manganese liners in the crusher. The normal time period between manganese changes would not be significantly different between the 7 Ft. and a 10 Ft. because the wear rate, that is, the pounds of liner worn away per ton of ore crushed, will remain the same. Consequently, if a set of liners in a 7 Ft. crusher, lasted six weeks, a 10 Ft. crusher in the same operation would also last approximately six weeks. However, since the total amount of ore crushed will be greater, the maintenance costs per liner changeout will be less on the 10 Ft. crusher.
Another point for consideration is that the 10 Ft., cone crusher is a secondary crusher and normally would be fed with the product of a gyratory crusher. Since the 10 Ft. can accept a larger feed than a 7 Ft. crusher, it is possible to increase the open side setting of a gyratory crusher, thereby, allowing a greater volume of feed to pass through the crusher. Because of this, it is conceivable that a smaller primary crusher could be used in order to obtain a given quantity of ore.
A good salesman could expound on a multitude of ideas for using 10 Ft. crushers in place of 7 Ft. crushers in a new plant, but in the final analysis, the deciding factor as to whether or not the 10 Ft. crushers should be used will be the anticipated over-all plant capacity. Several studies have indicated that as a general rule of thumb the break even point for using 10 Ft. crushers in place of 7 Ft. crushers is a plant which will have an overall ore treatment capacity of approximately 40,000 TPD or approximately 8,000,000 TPY. Anything less than that figure should indicate the use of conventional 7 Ft. crushers. Obviously a small four stage crushing plant in which the third stage crusher was a 7 Ft. Standard and the fourth stage consisted of two 7 Ft. SHORT HEAD cone crushers, would not improve economically by the use of one 10 Ft. Standard cone crusher and one 10 Ft. SHORT HEAD cone crusher in place of the 7 Ft. crushers.
A study was made which considered a plant to be built using three different approaches of a conventional crushing-grinding operation. The plant which was being considered would be crushing taconite similar to that found in the Iron Range. The end product of the crushing was 5/8 rod mill feed and in this example the plant capacity was to be approximately 13.5 million TPY of ore processed to eventually produce approximately 4 million TPY of iron ore pellets. The study arbitrarily chose a four-year period of operation so that operating costs would be included and also because a four-year period is the usual comparison basis for calculating return on investment. In this example the primary crusher as well as the fine crushing plant would be operated fourteen shifts per week.
In our economic analysis of the 10 Ft. crusher development program, we also studied how this crusher could be used to best advantage when planning expansion of an existing plant. Before delving into the actual dollars and cents of several variations of expansion plans, several preliminary questions must be answered in the affirmative:
Since each plant is unique, the relative merits of the 10 Ft. crusher must be examined on an individual plant basis. Again, as a general rule of thumb, it has been found that the most benefit can be achieved in those plants which presently contain a four-stage crushing plant in which the first two stages of crushing are gyratory crushers. Studies have shown that converting the second stage gyratory crusher to a 10 Ft. Standard crusher shows most potential because the major auxiliaries required for the crusher, such as crane, conveyors, etc., are already large enough to accommodate the increased capacity of the 10 Ft.
As one possible solution, we suggested that the two 30 x 70 secondary gyratory crushers be replaced by two 10 Ft. Standard cones. These crushers could then send approximately 3600 TPH of minus 3 material to the fine crushing plant. The two existing 7 Ft. Standard crushers could be converted easily to SHORT HEAD crushers and two new 7 Ft. SHORT HEAD crushers added to the existing vacant foundations.
In Summary, we feel that the Symons cone crusher has a very definite place in the future of the mining industry and we intend to move steadily ahead with its progress. However, we have learned a few lessons along the way.
Initially, the development of these super size machines is an extremely expensive proposition. We know that if our company alone, attempted to completely design, manufacture, erect, and test a machine in this size range, it would severely tax our financial resources.
We found that super size equipment also presents some problems for our manufacturing facilities. The manufacture of one of these units puts a large dent into the production schedule of many of the smaller conventional units. In our enthusiasm to build a bigger newer machine, we continually remind ourselves that the smaller conventional units are still our bread and butter units.
On the positive side, we found that our reputation as a crusher manufacturer was enhanced because of what our customers refer to as progressive thinking. We listened to the suggestions of the mining industry in attempting to give them what they wanted.
Perhaps you will allow me to close with a bit of philosophizing from a manufacturers point of view. The 10 Ft. crusher is here ready to go into operation. Where do we go from here? A 15 Ft. cone crusher? A 20 Ft. cone crusher? Who knows? We do know that we have reached the financial limit of a development program on a machine of this size. We also know that as the size of a machine grows larger, the developmental and manufacturing risks grow larger along with it and any allowable margin for error must be minimized. We, like you, are in business to make a profit. Since larger crushers usually mean a fewer number of crushers, we must examine the profit picture from aspects of the sale. I think I speak for other manufacturers as well when I say that bigness in machines reflects bigness in development costs as well. If the mining industry wants still larger equipment in the future, the industry should prepare itself to contribute to the development program of those machines.
A multi-cylinderHydraulic Cone Crusher, theHydrocone Cone Crushercan be used in either the second or third stage of crushing by merely changing liners and adaptors.It can produce the full product range that the combination of a comparable sized Standard and Short Head can produce. It makes the machine much more versatile. It allows for much more standardization. The value of this feature is one where spare parts investment in the form of major assemblies is minimized.
All operator controls are conveniently mounted on a remote control console to eliminate the need for an operator to approach the crusher during operation.Over a period of years we have developed a unique engineering knowledge about the effects of cone crusher design parameters such as speed, throw and cavity design on crusher productivity.
Each Hydrocone Cone Crusher features dual function hydraulic cylinders that provide overload protection and a safe and fast way to clear a jammed cavity. Should the crusher become plugged, the operator merely pushes levers on the remote control console to clear the cavity.
It can produce the full product range that the combination of a comparable sized Standard and Short Head can produce. It makes the machine much more versatile. It allows for much more standardization. The value of this feature is one where spare parts investment in the form of major assemblies is minimized.
All operator controls are conveniently mounted on a remote control console to eliminate the need for an operator to approach the crusher during operation.Over a period of years we have developed a unique engineering knowledge about the effects of cone crusher design parameters such as speed, throw and cavity design on crusher productivity.
Each Hydrocone Cone Crusher features dual function hydraulic cylinders that provide overload protection and a safe and fast way to clear a jammed cavity. Should the crusher become plugged, the operator merely pushes levers on the remote control console to clear the cavity.
TheHydraulic Cone Crusheruses hydraulic tramp release cylinders and accumulators to hold the adjustment ring against the main frame seat. There is only one angular surface between the main frame and the adjustment ring which also has a radial contact point in the lowermost area. When a piece of tramp goes through the crusher, the oil is forced into the accumulators allowing the adjustment ring to raise and pass the tramp.
The tramp release cylinders are secured to the adjustment ring and the lower portion of the main frame through clevises. This allows the crushing forces to be transferred directly from the frame arm locations to the adjustment ring. This relieves the main frame shell and upper flange from carrying heavy loads.
The Hydraulic Cone Crusher is equipped with hydraulic clearing. The tramp release cylinders which hold the adjustment ring in place are double acting cylinders. These cylinders can be pressurized in the opposite direction, after the clamping pressure has been released, to raise the adjustment ring and bowl assembly for clearing; only the weight of the adjustment ring, clamp ring, and bowl assembly, plus any residual material in the bowl hopper raises.
cone crusher - tips of operation and regular maintenance | hxjq
During the using process, if the worker operates and maintains the crusher according to correct standards, it will have great significance in normal production, output, quality, service life, working efficiency and the prevention of accidents, etc.
At present, the common cone crushers are mainly the single toggle cone crusher and compound cone crusher (Symons cone crusher). Although both types of cone crushers are totally different, they have the same operation procedure.
The operation procedure of cone crusher can be divided into four stages: before the start, at start-up, at run time and turning-off time. All conditions should be paid attention in each stage, and the potential problems can be found and solved timely and the service time can be prolonged.
Turn on the lubricating oil pump to run for three to five minutes. After everything runs well, turn on the crusher as required. After the crusher idles for one to two minutes, confirm that all things are well, and feed the rocks or stones.
During the crushing process, there is a great impact on the concave which makes the filled zinc layer be out of shape. Therefore, the U-type bolt should be tightened frequently to make the concave fix and avoid concave from deformation.
The mantle is fixed by the upper bolt of the main shaft. The looseness of the bolt can make the mantle unstable, even the filled layer may fall off to cause downtime. Hence, the bolts should be often checked and fixed to avoid looseness.
The spherical bearing should be installed in the borehole of crusher closely. After a long period of working, the tightness of crusher' parts can be broken. The tightness of spherical bearing must be checked frequently, and the oil gallery of the spherical bearing should be kept clean.
Water seal is the equipment for preventing crusher from dust, which is very important to the normal operation of cone crusher. Therefore, daily maintenance and checking its integrality are very necessary.
Through the study of this article, you must have a deeper understanding of the operation and maintenance of the cone crusher. In the case of the above-mentioned failure of the crusher, the problem is analyzed and solved by referring to the method given in this article.
cone crushers for sale
The cone crusherwas designed primarily with a view to achieving top performance in the field of fine-reduction crushing. It has also been adapted to what is designated simply as fine crushing, which extends into a range below that ordinarily defined by the term fine-reduction. Although the eccentric speeds of the various sizes of this type are not quite so high as the speeds used for the Newhouse crusher, the Hydro-cone crusher definitely rates as a high-speed machine, its product comparing quite closely to that of the former type, for equal close-side settings.Probably the outstanding feature of the. Hydrocone crusher is the hydraulic support, from which its name is derived and which is clearly shown in the sectional view. This device makes it possible to adjust the crusher to any desired setting within its range in a matter of seconds;adjustments may be made while the crusher is running, although the feed must be shut off before operating the adjusting pump. An accumulator in the hydraulic system provides protection against tramp iron or packing.
Cone crushers are used in AG and SAG grinding circuits to increase tonnage by effectively dealing with any pebble (critical size) build-up problem. Normally, heavy-duty short-head crushers are employed to crush pebbles. Power and crusher cavity level are the key variables for monitoring and controlling the crusher operation. Crusher product size is adjusted by changing the closed side setting.
On the left is a diagram of the Hydro-cone crushing chamber. A comparison of this chamber with those previously discussed is interesting. It will be noted that the choke-point has been raised far above the discharge level, in fact, to a point not far below the nip-point for the recommended maximum one-way feed dimension. By virtue of the decided flare of the head, and the corresponding flare of the top shell bore, the line-of-mean-diameters slopes sharply away from the crusher centerline. For some, distance above the discharge point the angle between head and concave is very acute; in fact, at the open-side position of the head, this zone is almost parallel. For recommended operating conditions, i.e., for safe combinations of throw and setting, and with screened feed, this type of crushing chamber does not approach anything like a choke or near-choke condition. For the combination shown in the diagram the ratio of volume reduction is almost 1:1 from zone 0-1 to zone 2-3 at the choke-point; consequently, if the crusher is given a screened feed (as all fine-reduction crushers should be) the reduction in voids by the time the choke-point is reached cannot very well reach serious proportions. The diagram shows the standard chamber. With screened feed, these crushers will operate at closed-side discharge settings equal to the throw of the head at the discharge point (usually spoken of as eccentric-throw.)
The level in the crusher feed pocket is an important variable since it can indicate whether the feed is building up. A build-up could lead to a plugin the feed chute, a spill through the skirting on the crusher feed, or a crusher plug. None of these are desirable.
In a normal feed situation, the level in the crusher cavity is kept fairly low, just enough to ensure that there is sufficient feed to keep the crusher working, but if the feed has to be suspended suddenly because of impending plugging, the crush-out wont take too long (10 seconds or less). Normal feed is usually used in standard crushers where the feed particle size is quite large, say greater than 65 mm.
Choke feed is when the crusher cavity is kept full, without spilling out through the skirting. Choke feeding is usually used in short-head crushers where the feed particle is smaller than that for a standard crusher.
This crusher is a modification of the standard machine, developed for fine-crushing duty. Mechanically, the machine is the same in every respect as the standard crusher of the same type, but for each developed size of machine a special top shell and the concave ring has been designed, with reduced receiving opening, reduced angularity between head and concave, and, consequently, superior characteristics at the finer settings. Medium crushing chambers may be operated at close-side settings of one-half the eccentric-throw, on screened feed; hence capacities at the finer settings are better than those of the standard type. Fine crushing chambers operate at one-fourth the eccentric throw. Inasmuch as the maximum feed size is smaller in the case of the fine chamber, the ratios of reduction are approximately the same for both machines.
There are two main types of cone crushers: standard and shorthead. They differ by the shape of the cavity. The standard crusher cavity is wider to accommodate larger feed-size material. The short head crusher is designed to crush finer material and to produce a finer product.
The closest approach between the mantle and the bowl liner is called the closed side setting. This is usually specified by the metallurgist to give the desired crusher product discharge size. It can be checked by running the crusher empty, hanging a lead plug into the crusher bowl, and then removing it to measure the gap. The gap is adjusted by rotating the bowl. Some crushers are equipped with a hydraulic jack mechanism on the crushing head assembly instead of having a bowl adjustment ring. The head can be raised or lowered to meet the operators needs. It can be very helpful in operation and process control.
The Symons Cone Crusher has come into almost universal use during the last few years for the final stage of crushing. It is a development of the secondary gyratory crusher, which is merely a small gyratory crusher designed to break the product of the primary machine down to about 1-in. size; but the main shaft of a cone crusher instead of being suspended from a spider is supported on a large socket bearing situated immediately under the crushing head and protected from grit and dust by a sealing assembly, this bearing taking the whole of the crushing load.
Fig. 8 gives a sectional view of the machine. The main shaft is carried in a long gear-driven eccentric, the rotation of which causes the gyration of the head in the usual way, but the center of gyration is at the apex of the crushing head instead of in the spider. At the top of the bowl, therefore, the lumps of ore entering the crushing zone are cracked by short powerful strokes; but at the bottom the head has a much longer but less powerful stroke, enabling the ore in the finishing stages to be rapidly crushed and quickly discharged without any tendency to choke, a condition which reduces over crushing to a minimum. This, together with the curved shape of the bowl, accounts for the large reduction ratio possible with this type of machine and makes it superior to other secondary crushers and coarse rolls.
It will be seen that the head and the bowl are parallel at the lower part of the crushing zone. The parallel space is deep enough, in conjunction with the speed of gyration, to ensure that no piece of ore can pass through it without being struck two or three times by the head before it falls clear. It follows that, unlike the jaw and gyratory crushers, the size of the product is determined by the distance apart of the bottom edges of the head and bowl in the position when they are closest together.
Coarse buttress threads on the outer circumference of the bowl fit into corresponding threads on the inner side of the adjusting ring, which is held down to the mainframe by a circle of long heavy springs, flexible enough to allow the whole assembly to rise should tramp iron or other uncrushable material enters the crushing zone. By means of a windlass and chain, the bowl can be rotated in the threads that support it in the adjusting ring while the machine is running, thus enabling the bowl liner to be adjusted for wear or the size of the product to be changed without stopping. The cone crusher is usually set to give a 3/8-in. or -in. product when discharging to ball mills.
Table 9 gives particulars of the different sizes of crushers. The capacity figures are based on material weighing 100 lb. per cubic foot and must be increased in direct proportions for heavier ores. It will be noted that each size of machine has two ranges of capacity; this is due to the fact that it can be fitted with a coarse or a fine crushing bowl according to the duty that is required of it. With either one, the range of reduction is greater than is economically possible with any other type of dry crushing machine.
A possible disadvantage of the cone crusher is that as a rule it cannot be choke-fed, but must be given an even feed of ore if it is to do efficient work. Should circumstances call for the installation of a machine that can be run if necessary with the ore piled up over the top of the head, a secondary gyratory crusher of the suspended shaft type will be required. The Traylor Reduction Crusher Type TZ, which is constructed on the principles of an ordinary gyratory crusher, but is fitted with a curved bowl liner similar to that of the Symons Cone Crusher, is designed to meet the case. Although the suspension of the shaft restricts the movement of the head to a smaller circle of gyration than that of the cone crusher, the ratio of reduction is still large enough to enable it to crush the product of the primary breaker to -in. size (-in. for the large machines), and it fulfills the condition that it can be choke-fed. Owing to the smaller movement of the head, however, the capacity for a given range is much less than that of the equivalent size of cone crusher, and the latter is therefore preferred when choke-feeding can be avoided.
The Symons Shorthead Cone Crusher, which is constructed on the same general principles as the larger machine, is designed to follow the latter, taking its product at 1-in. and reducing it to about -in. size. The strains imposed on the crushing members, however, would be very heavy if the machine were run with the discharge opening set to -in. or less. It is usual, therefore, to crush in closed circuit with a screen, the discharge opening of the bowl being set to 5/8 or in. Thus a circulating load is built up and a certain amount of choke-crushing takes place, but the method actually gives greater efficiency with a finer product than can be obtained in an open circuit, whatever the discharge setting of the bowl in the latter case.
In ordinary crushing practice, the grinding section is supplied with -in. or 3/8-in. material direct from Symons Cone Crushers. But the demand is for a finer feed and it seems likely that the Shorthead Cone Crusher will satisfy this demand to the exclusion of fine crushing rolls.
Symons Cone Crushers have been used extensively for secondary crushing in metallic, non-metallic, rock products, and industrial operations. The Symons Cone was developed to give large capacity, fine crushing. The combination of high speed and wide travel of the cone results in a series of rapid, hammer-like blows on the material as it passes through the crushing cavity and permits the free flow of material through the cavity.
Reduction in size of any particle, with each impact of the head, is regulated by the opening between the head and bowl at that point. A threaded arrangement of the bowl affords a quick and easy method for changing the size of the product or to compensate for wear. This adjustment can be made while the crusher is operating. A parallel zone between the lower portion of the crushing members assures uniform sizing.
Frame, adjustment ring, and cone are made of cast steel; gears are made of specially treated steel and have cut teeth; all bearings are bronze; mantle and bowl liners are manganese steel. The head and shaft can be removed as a unit, and other parts such as the eccentric and thrust bearings can easily be lifted out after the head is removed. The countershaft assembly can also be removed as a complete unit.
The circle of heavy coil springs, which holds the bowl and adjustment ring down firmly onto the frame, provides automatic protection against damage due to tramp iron. These springs compress, allowing the bowl to rise the full movement of the head until non-crushable material passes through. The springs then automatically return to their normal position.
Symons Cone Crushers are made in Standard and Short Head types. They are of the same general construction but differ in the shape of the crushing cavity. The Standard cone is used for intermediate crushing. The Short Head cone is used for finer crushing. It has a steeper angle of the head, a shorter crushing cavity, and greater movement of the head at the top of the crushing cavity.
If you observe the illustrations you will notice that the center line of the main shaft is at an angle to the center line of the crusher. The center of the main shaft bisects the center line of the crusher at the opening of the crushing chamber. As the MANTLE revolves that point is the pivot point of the mantle. This means that both the top and the bottom of the crusher mantle have a circular gyrating motion.
Tramp iron had long been a source of worry to those engaged in fine crushing.Here is what one operator had to say.Shutdowns were frequent, costs were uncertain because of enforced delays due to excessive breakage. Plugged machines had to be freed continually with a torch tocut out frozen and wedged-in tramp iron.The cone crusher overcame these troubles,helped reduce and stabilize costs. The bestevidence of this statement is the universalacceptance of the cone as the outstandingcrusher in its field.
While tramp iron is not recommended as a regular diet for a Cone Crusher, its construction is such that damage will not result should any ordinary noncrushable material get into the crushing cavity. The band of heavy coil springs encircling the frame allows the bowl to lift from its seat with each movement of the head until Such non-crushable object passes off into the discharge. The tramp iron shown in the accompanying illustration passed the protective devices installed for its removal and would have resulted in expensive repairs and long shutdown periods for any crusher except the Symons Cone.
Cone crushers can have two types of heads, standard and short head types. The principle difference between the two is in the shape (size and volume) of the crushing cavities and feed plate arrangements. Standard head cone crushers have cavities that are designed to take a primary crushed feed ranging up to 300mm generating product sizes around 20mm to 40mm. For finer products, short head cone crushers are normally used. They have a steeper angle of the head and a more parallel crushing cavity than the standard machines. Due to the more compact chamber volume and shorter working crushing length, the much needed higher crushing forces/power can be imparted to the smaller-sized material being fed to the crusher. Cavities for the short head machine are designed to produce a crushed product ranging from 5mm to 20mm in a closed circuit.
At the discharge end of the cone crusher is a parallel crushing section, where all material passing through must receive at least one impact. This ensures that all particles, which pass through the cone crusher, will have a maximum size, in at least one dimension, no larger than the set of the crusher. For this reason, the set of a cone crusher can be specified as the minimum discharge opening, being commonly known as the closed side setting (CSS).
Here are facts about the conecrusher known as Hydrocone. This line of hydraulically adjusted gyratory crushers was developed in smaller sizes some fifteen years ago by Allis-Chalmers to meet a demand for improved secondary or tertiary crushing units. The line is now expanded to include sizes up to 84-in. diameter cones.
This modern crusher is the result of many years of experience in building all types of crushing equipment, when the first gyratory or cone crusher, the Gates, was put into operation. Overall these years AC has followed a continuing policy of improvement in crusher engineering, changes in design being based on operating experience of crushers in actual operation.
The Hydrocone cone crusher is the logical outgrowth, a crusher having a means of rapidly changing product size or compensating for wear on the crushing surfaces a crusher which produces a better, more cubical product than any comparable crusher and a crusher so designed that it can be operated and maintained with a minimum of expense.
The most important fact about the Hydrocone crusher is its hydraulic principle of operation. Hydraulic control makes possible quick, accurate product size adjustments fast unloading of the crushing chamber in case of power failure or other emergency protection against tramp iron or other uncrushable materials in the crushing chamber. Another important fact about this crusher is its simplicity of design and operation. The accompanying sketch shows the simplicity of the Hydrocone crushers principle of operation. The main shaft assembly, including the crushing cone, is supported on a hydraulic jack. When oil is pumped into or out of the jack the mainshaft assembly is raised or lowered, changing the crusher setting.
Since the crushing cone is supported on a hydraulic jack, its position with respect to the concave ring, and therefore the crusher setting, can be controlled by the amount of oil in the hydraulic jack.
Speed-Set control raises or lowers the crushing shaft assembly hydraulically, and permits quick adjustment to produce precise product specifications without stopping the crusher. Speed-Set control also provides a convenient way to compensate for wear on crushing surfaces.
On Hydrocone crushers in sizes up to 48-in., the Speed-Set device is a hand-driven gear pump; on the larger sizes a motor-driven gear pump operated by push-button. On all sizes the setting can be changed in a matter of minutes by one man without additional equipment, reducing downtime materially.
Protection against tramp iron or other uncrushable materials is afforded by an accumulator in the hydraulic system. This consists of a neoprene rubber oil-resistant bladder inside a steel shell. This bladder is inflated with nitrogen to a predetermined pressure higher than the average pressures encountered during normal crushing.
Ordinarily, the Automatic Reset remains inoperative, but if steel or some other foreign material should enter the crushing chamber, the oil pressure in the hydraulic jack will exceed the gas pressure in the accumulator. The bladder will then compress, allowing the oil to enter the steel shell. This permits the crushing cone to lower and discharge the uncrushable material without damage to the crusher.
After the crushing chamber is freed of the foreign material, the gas pressure in the accumulator will again exceed the oil pressure in the hydraulic system. Oil is then expelled from the accumulator shell and the crushing cone is returned to its original operating setting automatically.
A Hydrocone crusher will produce a cubical product with excellent size distribution and a minimum of flats and slivers. This is especially important in the crushed stone industry where a cubical stone is required to meet rigid product specifications. It is also of considerable significance in the mining industry where the elimination of large amounts of tramp oversize reduces circulating loads or makes open circuit crushing possible.
The reason why the Hydrocone crusher will produce such a uniform, cubical product is that it has a small eccentric throw with respect to the crusher setting. This means a smaller effective ratio of reduction during each crushing stroke, and therefore, the production of fewer fines and slivers. Likewise, a small eccentric throw means a small open side setting, which results in a smaller top size of the product. A large percentage of the product from a Hydrocone crusher will be of a size equal to or finer than the close side setting.
For fine crushing, or in installations where the feed to the crusher is irregular, the use of a wobble plate feeder is recommended. This feeder is installed in place of the spider cap and affords a means of controlling the feed to the crusher, as well as a means of distributing the feed evenly around the crushing chamber.
Essentially, the feeder consists of a plate that is oscillated by a shaft extending down into the crushers main shaft. The motion of the main shaft oscillates or wobbles the feeder plate. The plate is supported on a rubber mounting which permits its motion and, at the same time, positively seals the top of the spider bearing against the entry of dust. Maintenance is reduced by the use of self-lubricating bushings between the feeder plate shaft and the crusher main shaft.
Hydrocone crushers are mounted on rubber machinery mountings in order to reduce installation costs and make it possible to locate these machines on the upper floors of crushing plants. These mountings operate without maintenance, absorb the gyrating motion of the crusher, thereby eliminating the need for massive foundations. Rubber mountings also prolong the life of the eccentric bearing, since this bearing is not subjected to the severe pounding encountered when rigid mountings are used.
The exclusion of dust and dirt from the internal mechanism of the crusher is of extreme importance from a maintenance standpoint. To accomplish this, Hydrocone crushers are equipped with one of the most effective dust seals yet devised.
This seal consists of a self-lubricating, graphite impregnated plastic ring which is supported from the head center in such a way that it is free to rotate, or gyrate, independently of the head center.
The plastic ring surrounds the dust collar with only a very slight clearance between the two parts. With the plastic ring being free to move as it is, it accommodates the rotation, gyration, and vertical movement of the main shaft assembly, maintaining the seal around the dust collar at all times. Because of its lightweight and self-lubricating characteristics, wear on the plastic ring is negligible.
The ease with which any wearing part can be replaced is of the utmost importance to any crusher operator. With this in mind, the Hydrocone crusher has been designed so that any part can be replaced by disturbing only a minimum number of other parts.
For example, the Mantalloy crushing surfaces are exposed by simply removing the top shell from the crusher. This can be done easily by removing the nuts from the studs at the top and bottom shell joint. The eccentric and hydraulic support mechanisms are serviced from underneath the crusher without disturbing any of the feeding arrangements, or the upper part of the crusher.
Efficient lubrication of all wearing parts is one of the reasons why crushing costs are low with the Hydrocone crusher. On most sizes, lubrication is divided into three distinct systems, each functioning independently.
This bearing, whether of the ball and socket type as on the smaller sizes, or of the hourglass design (as shown) found on the larger Hydrocone crushers, is pool lubricated. On the 51, 60 and 84-inch sizes, provision is made for introducing the lubricant from outside the top shell through the spider arm. On the smaller crushers, oil is introduced through an oil inlet in the spider cap. On all sizes, oil is retained in the bearing by a garter-type oil seal located in the base of the spider bearing.
All Hydrocone crushers are provided with a compact external lubrication system consisting of an oil storage tank, an independently motor-driven oil pump, a pressure-type oil filter, and a condenser-type cooler.
Cool, clean oil is pumped into the crusher from the conditioning tank, lubricating first the three-piece step bearing assembly. The oil then travels up the inner surface of the eccentric, lubricating the eccentric bearing and main shaft.
At the top of the eccentric, the oil is split into two paths. Part of the oil flow passes through ports in the eccentric and down its outer surface, lubricating the bronze bottom shell bushing, driving gears and wearing ring. On the 48-in. and smaller crushers, the balance of the oil overflows the eccentric and returns over the gears to the bottom of the crusher where it flows by gravity back into the conditioning tank. On the 51-in. and larger Hydrocone crushers, any oil which overflows the top of the eccentric is returned directly to the conditioning system without coming into contact with the gears.
On all but the 36 and 48-in. Hydrocone crushers, the countershaft bearings are of the anti-friction type with separate pool lubrication. Both ends of the countershaft bearing housing are sealed by garter spring-type oil seals to prevent dirt or other contaminants from entering the system.
Rather than use one eccentric throw under all operating conditions, Hydrocone crushers are designed to operate most efficiently with a predetermined ratio of eccentric throw to the crusher setting. By operating with an eccentric throw specifically selected for a given application, the most desirable crushing conditions are attained the most economical use of Mantalloy crushing surfaces reduced crusher maintenance a more cubical product.
The eccentric throw is controlled by a replaceable bronze sleeve in the cast steel eccentric. This sleeve, being a wearing part, can be renewed readily in the field. Also, should operating conditions change, the throw or motion of the crushing head can be changed accordingly.
Because of the large choice of eccentric throws available and the variety of crushing chambers that may be obtained a Hydrocone crusher may be selected that will fulfill the requirements of almost any secondary or tertiary crushing operation.
They may be used in the crushed stone industries to produce a premium cubical product in the mining industries to produce a grinding mill feed having a minimum of oversize, thereby reducing circulating loads and making open circuit crushing possible. The Hydrocone crusher is used in the cement industry to reduce cement clinker prior to finish grinding.
One of three general types of crushing chambers can be furnished for any size Hydrocone crusher to suit your specific needs. The selection of the proper chamber for a given application is dependent upon the feed size, the tonnage to be handled and the product desired. A crusher already in use can be readily converted to meet changing requirements, making this machine highly flexible in operation.
The Coarse crushing chamber affords the maximum feed opening for a given size crusher. Crushers fitted with a Coarse chamber can be choke fed, provided that product size material in the feed is removed.
The Coarse chamber has a relatively short parallel zone and is designed to be operated at a close side setting equal to or greater than the eccentric throw. For example, a crusher with a 3/8-in. the eccentric throw should be operated at a 3/8-in. (or more) close side setting, and therefore a -in. open side setting. Optimum capacity and product will result when operated under these conditions, as well as most economical wear on the mantalloy crushing surfaces.
One way dimension (slot size) of the feed to a crusher fitted with a Coarse chamber should not exceed two-thirds to 70 percent of the feed opening. The maximum feed size to an 848 Hydrocone crusher would therefore be about 5-in. one way dimension.
The use of a wobble plate feeder, furnished as optional equipment, is recommended if the feed size is relatively large, if the crusher is to be operated in closed circuit, or if the feed to the crusher is irregular.
If the Hydrocone crusher is operated with a Coarse crushing chamber, the product will average about 60% passing a square mesh testing sieve equal to the close side setting of the crusher. On certain materials which break very slabby, this percentage will be somewhat lower, and on cubically breaking material the percentage will be somewhat higher. As an average, approximately 90% of the product will pass a square mesh testing sieve corresponding to the open side setting, although this percentage frequently runs higher.
The Intermediate crushing chamber has a feed opening somewhat less than a coarse crushing chamber, but because of its longer parallel zone, is designed to be operated at a close side setting equal to or greater than half the eccentric throw. For example, with a -in. eccentric throw, the minimum close side setting would be 3/8-in.
Crushers fitted with this type of chamber can be choke fed, provided that product size material in the feed be removed ahead of the crusher. The one-way dimension or slot size of the feed to a crusher should not exceed approximately half the receiving opening. A 436 Hydrocone crusher with a 5/8-in. the eccentric throw could be operated at 5/16-in. close side setting and feed size should not exceed 2-in. one-way dimension.
The wobble plate feeder, although not required under most circumstances, is recommended if the feed is irregular, or if the crusher is operated as a re-crusher, at a relatively close setting, or in a closed circuit.
Because of the longer parallel zone in this crushing chamber, a somewhat greater percentage of the product will pass a square mesh testing sieve equal to the close side setting. This will usually average about 65 to 70%, with this percentage varying, depending on the material being crushed. Very frequently, 100% of the product will pass a square mesh testing sieve equal to the open side setting of the crusher.
The Fine crushing chamber has the longest parallel zone and therefore the smallest feed opening for any given size crusher. It can be operated at ratios of eccentric throw to close side setting of up to 4 to 1. With a -in. throw, for example, a 236 Hydro-cone crusher could be operated at 3/16-in. on the close side.
Because of their design, crushers with Fine crushing chambers cannot be choke fed but must be equipped with the wobble plate feeder. The maximum one-way dimension of the feed approaches the crusher feed opening. A 348 Hydrocone crusher can be fed with material up to 3-in. one-way dimension.
The Fine crushing chamber will give the highest percentage passing the close side setting of any of the chambers discussed here. The product will average approximately 75% passing a square mesh testing sieve equal to the close side setting. Because of the long parallel zone, the top size of the product will be only slightly larger than the close side setting of the crusher.
In addition to the three general types of crushing chambers described here, special chambers can be designed to meet varying operating requirements, giving the crusher even greater flexibility than can be obtained with these three main types.
For example, a special concave ring can be used in a 636 Hydro-cone crusher which will reduce the feed opening to 5 inches and permits a two to one ratio of eccentric throw to close side setting. Thus, the crusher can be furnished to fit the exact requirements of any application.
The following capacity table gives a complete range of all Hydrocone cone crusher capacities with varying crushing chambers and eccentric throws. This table shows the minimum recommended setting for any given eccentric throw, the recommended maximum one-way (slot size) dimension of the feed, and the maximum recommended horsepower for any eccentric throw.
Capacities given are based on crushing dry feed from which the product size material has been removed. The material must readily enter the feed opening and be evenly distributed around the crushing chamber. The table is based on material weighing 100 lb per cubic foot crushed. Any variation from this must be accounted for.
The curves on the following page can be used to approximate the screen analysis of the product from any given Hydrocone crusher. These curves are only approximations since the actual screen analysis of the product of a Hydrocone crusher will depend upon the nature of the material being crushed, the feed size and a number of other considerations which could not be taken into account in these curves. Within these limits, the curves should give fairly accurate estimates.
Note that the Coarse crushing chamber is represented as giving a product of which 60 percent will pass the close side setting, the Intermediate chamber 67 percent and the Fine chamber 75 percent passing the close side setting. These percentages are the averages of a large number of tests and some variations from these must be expected. If material breaks slabby the percentage with a coarse crushing chamber may be as low as 50 percent; if it breaks very cubically it might be as high as 70 percent, or even higher.
These curves have been prepared so that they can be used for any crushing chamber. To estimate the product of any Hydrocone crusher, it is necessary to know the type of crushing chamber used (Coarse, Intermediate or Fine), the close side setting and the eccentric throw.
If the crusher is a 636 Hydrocone crusher with a 3/8-in. throw and a 3/8-in. close side setting, the approximate screen analysis would be the curve that would pass through the 3/8-in. horizontal line and the vertical line representing the close side setting for the Coarse crushing chamber, which is the 60 percent passing line. If no curve passes through the precise point of intersection between the horizontal and vertical lines, an approximate curve can be sketched in which parallels the other curves. The same procedure can be used for approximating the products from any other crushing chamber.
Barite..170 Basalt.100 Cement Clinker.95 Coal..40-60 Coke.23-32 Glass..95 Granite100 Gravel.100 Gypsum..85 Iron Ore.125-150 Limestone..95-100 Magnesite.100 Perlite..95 Porphyry.100 Quartz..95 Sandstone..85 Slag..80 Taconite125 Talc..95 Trap Rock100
We canprovide testing to solve the most difficult crushing problems. Laboratory equipment makes it possible to measure the crushing strengths and characteristics of rock or ore samples accurately, and this data is used in the selection of a crusher of proper size and type.
Impact and batch tests are frequently sufficient to indicate the type and size crusher that will be the most economical for a particular application. However, batch testing is often followed by pilot plant tests to provide additional information about large-scale operations, or to observe rock or ore reduction under actual plant operating conditions.
Pilot plant tests duplicate a continuous crushing operation provide a practical demonstration of the commercial potential of the process on a pilot scale. Such tests are useful because they may disclose factors that affect the full-scale operation, favorably or otherwise, but which remain hidden in tests on limited samples.
All Laboratory tests are guided by modern scientific knowledge of crushing fundamentals and by ourinvaluable backlog of experience in engineering and building all types of crushing equipment for any crushing application.
In addition to the facilities for crushing tests, the Laboratory maintains complete batch and pilot mill facilities for use in investigating an entire process. Tests in grinding, sizing, concentrating, thickening, filtering, drying, and pyro- processing can be made.