types of crushers
Impact Crushers: This division is represented chiefly by the various styles of hammermill; also by the cage type disintegrator.
Combination Impact and Sledging Crushers. In this class we have the single or double sledging roll crushers. An example of the former is the Fairmount crusher, of the latter, the Edison roll crusher.
Some further subdividing and qualification might be applied to these general classifications, but these, for the most part, are not of particular importance. Pressure crushers, for example, may be divided into two subclasses: the reciprocating, and the continuous-pressure, types. The gyratory and jaw crushers come under the first category, the crushing rolls under the second. Strictly speaking, the gyratory motion is not a reciprocating one, but it is so with respect to any vertical radial plane through the crushing chamber; therefore it is convenient to view it in that light. Some roll crushers, notably the light coal crushing type, have more of a tearing action, as contrasted to the heavy sledging performance of such machines as the Fairmount crusher.
During the same years wherein the industry was concerned with development of larger and still larger primary crushers,another member of the family was born: the single, sledging- roll crusher. The Allis-Chalmers Co. entered this field in 1911, building two sets of 36 dia. x 60 face single-roll crushers, flux limestone plant. Taking the name of its proving ground, this machine was christened the Fairmount crusher. The machine quickly achieved a high degree of popularity, and although its field of application is relatively limited, quite a number of them were in-stalled for primary crushing service. The line was expanded to include smaller sizes, as well as the big 60- x 84-in. machine.
Development of concentration and cyanidation in the mining industry called for finer crushing than was feasible in the gyratory or jaw crushers then available. This requirement was met for a number of years by the double smooth-face crushing rolls, originally known as Cornish rolls. As the mining industry during the period we are discussing was a very active one, the development in this type of crusher had reached a fairly high stage before the end of the century, and some excellent heavy-duty roils were available at that time. That this machine was not used to any considerable extent in the commercial crushing plants of that period was due simply to the fact that there was no demand for the smaller sizes of crushed stone, at least not any more than could be taken care of by the crushing methods then in vogue in such plants.
This brings us to the rather significant fact that, while all of the interesting and rather remarkable development we have outlined was going on, very little, if anything, was being done to develop special crushers for secondary and fine-reduction work, other than the work on crushing rolls just described.
a jaw, b cone, c mushroom, d hammer, e roller;
1 fixed cheek with the rotation axis; 2 a movable cheek; 3, 4 the eccentric shaft; 5 rod; 6 hinged rear bearing spacer cheeks; 7 spring; 8, 9 width adjustment mechanism of the discharge gap; 10 pull the lock device; 11 bed; 12 still cone; 13 cone moving; 14 traverse; 15 hinge suspension rolling cone; 16 cone of the shaft; 17 drive shaft; 18 eccentric; 19 amortization spring; 20 foot ring ;21 regulating ring; 22 thrust bearing cone; 23 rotor; 24 liner plates; 25 grate; 26 hammer; 27 main frame; 28 crushing rolls.
equipment you'll find at a typical surface mine - vector solutions
All of the terms, definitions, and images in this article come from our online MSHA Part 46 Typical Equipment in a Surface Mine training course. Weve included a short sample of that online mining safety course below.
Either track-mounted or tire-mounted, backhoes are a type of excavator equipped with a bucket that faces toward itself. The typical backhoe design incorporates an inward-facing bucket affixed to an articulated arm, or boom. Backhoes are often used for removing and loading overburden as well as scraping down high banks and digging ditches.
Bins and hoppers are containers with open tops for material to enter and an opening at the bottom for material to exit, typically over a conveyor or feeder. They are filled from the top by a loader or conveyor and discharge material at a continuous rate through the opening at the bottom for distribution to other processing and sorting operations.
Feeders transport material a short distance at a consistent rate using conveyor belts or screw conveyors. Feeders may also have an integrated breaker mechanism used to reduce material size as needed for the next processing stage.
Management offices, workshops, storage, refueling, and power generation may all be located on-site. In some cases, a control tower may also be constructed to offer a complete view of processing operations.
Some of the most common types of classifiers are spiral and rake classifiers. Both of these classifiers separate material by dragging the material along the bottom of an inclined surface in a settling chamber from the bottom (inlet) to the top (discharge).
Cone crushers are typically used in downstream crushing operations for medium-sized materials. Like the jaw crusher, the material is fed into the cone crusher from the top and discharged at the bottom. As the material enters the crusher, an eccentrically rotating cone forces the materials against a crushing plate. The shape and movement of the cone progressively reduces the size of material as it moves down through the crushing chamber to the sizing gap above the discharge opening. Resized material may be further sorted and transported to stockpiles or other processing operations.
Draglines, a type of specialized excavation equipment, operate by casting a heavy cable-hung bucket outward from a crane-like boom and dragging the bucket toward itself to remove large amounts of overburden, load ore, and manage stockpiles. Draglines can be equipped with buckets of specific design and weight to match the materials being mined.
Dredges are a type of excavation equipment used to remove material from underwater. They can be land-based or barge-mounted and may employ powerful suction or physical digging methods to bring material to the surface for removal or processing.
Front-end loaders, or simply loaders, are large, typically tire-mounted vehicles with a deep, wide bucket mounted at the front. Loaders are used to load mined material into haul trucks and feeders, push or dump overburden, and manage stockpile or refuse areas. In sand and gravel operations, loaders may also be used for excavation.
Surface mines require the constant operation of heavy equipment consuming large volumes of liquid fuel. Since much of this equipment is not designed to be driven on conventional roadways, refueling must be done on-site making fuel tanks and pumps a necessity. Tanks may be above or below ground and can range in size from 500 to many thousands of gallons.
Active mining operations are often spread across a large area, making walking to distant locations impractical and potentially dangerous. Miners, contractors, and supervisors often need to move quickly between work areas to do their jobs, perform maintenance, and address issues as they arise. A broad range of common passenger vehicles and pickup trucks may share haulage roads to transport people, tools, and small equipment where they are needed.
In-pit belt conveyors are used to move material within a large, active mining pit area or from the pit to loading areas for further distribution within the mine. In-pit conveyors may also move mined material to portable crushing systems that reduce the size of larger rocks or minerals for easier transport.
Jaw crushers are often used early in the production process to prepare material for processing. Raw mined material enters the top of the machine where a moveable jaw opens and closes repeatedly to break the material against a fixed stationary plate. When the material has been reduced to a size small enough to pass through the opening below the jaws, it exits the crusher and may be further sorted for stockpiling or downstream processing.
Most mines will have a maintenance and repair shop onsite to store replacement parts, supplies, tools, and other specialized machinery while providing sufficient space to maintain and repair equipment.
Overland belt conveyors are used on mine sites where there is the need for continuous movement of high volumes of material over long distances, in some cases, several miles. This type of bulk material handling conveyor may be used to transport material from the pit to processing areas or loading areas for rail or barge transport.
Scrapers are a type of earthmoving machine with an open, centrally mounted hopper or bowl with a blade-like leading edge that can be raised or lowered hydraulically to selectively remove and spread overburden over level or relatively level terrain.
Screw conveyors use a rotating, helical screw to move liquid or granular materials through a tube or trough. The screw is commonly referred to as a flighting and may either wrap in a spiral pattern around a central shaft or be shaftless.
Shovels, sometimes called power shovels, are versatile excavation machines, often track-mounted, with a large, outward-facing bucket at the end of a powerful, articulated boom that can rotate 360 degrees. Shovels are used primarily to dig out and remove overburden as well as selectively load material for transport.
Often tire-mounted, skid steers are quick, compact, highly maneuverable, and extremely versatile machines which perform a broad range of vital duties throughout the mine. They may be used in excavation work to carry, spread, and load loose material as well as serve an array of grading, site preparation, construction, demolition, and repair functions.
Track haulage involves the loading and management of specially designed railroad cars to transport enormous volumes of overburden or mined material to other areas of the mine or off-site to distant locations.
Since mining operations exist for the purpose of selling extracted and processed commodities, industrial truck scales are put in place to keep track of transported material volumes. Truck scales are normally situated on drive paths close to where over-the-road trucks exit the mine carrying processed material to customers.
Water reclamation systems remove fine sediments and return a high percentage of the used water back into the mining process. These systems may involve large settling tanks, mud presses, storm water discharge areas, and extensive piping and pumps to reduce runoff, manage environmental impact, and conserve resources.
Weve taken these terms and definitions and have put them together in a multimedia, interactive surface mining equipment glossary. Its cool, and theres even a way for you to download the interactive glossary for free. Go check it out.
Knowing the equipment at a surface mine will help you know whats what and get the job done. Especially if youre a brand new worker or a contractor whos been hired to work at a mine site. So we hope you found some value in this article.
Jeff Dalto, Senior Learning & Performance Improvement Manager
Jeff is a learning designer and performance improvement specialist with more than 20 years in learning and development, 15+ of which have been spent working in manufacturing, industrial, and architecture, engineering & construction training. Jeff has worked side-by-side with more than 50 companies as they implemented online training. Jeff is an advocate for using evidence-based training practices and is currently completing a Masters degree in Organizational Performance and Workplace Learning from Boise State University. He writes the Vector Solutions | Convergence Training blog and invites you to connect with him on LinkedIn.