Double Roll Crushers typically follow a primary or secondary crusher and are used for secondary and tertiary reduction of various minerals, such as ROM coal, clean coal, limestone, gypsum, trona, shale, bauxite, oil shale, coke, salt, lime, glass, kaolin, brick, shale and wet, sticky feeds.
Applications
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Double Roll Crushers are one of the most widely used crushers in the mining industry and have numerous advantages, such as high capacity, low headroom, low horsepower, the ability to handle wet, sticky feeds and the ability to produce a cubical product with minimum fines generation. Roll diameters and widths are dictated by the feed size, product size and capacity. The rule of thumb for the Double Roll Crusher’s ratio of reduction is 4:1.
The simplified design gives these units excellent reliability and requires very little maintenance. The crushers are designed with built-in tramp relief that allows for the passing of uncrushable objects while remaining in continuous operation and returning to the initial product setting. With a variety of roll surface designs, this crusher is capable of producing a much finer product. Since each machine is custom engineered, roll elements and tooth patterns are selected depending on each unique application.
Operating Double Roll Crushers is quite simple. Whether it is a single or dual drive arrangement, the rolls are powered by electric motors and V-belt drive configurations, resulting in reliable and quiet operation. If it is a single drive arrangement, power is transferred from the driven roll to the non-driven opposing roll by an interstage V-belt drive. If it is a dual drive configuration, each roll is powered independently through a motor and V-belt drive.
During normal operation, the material is fed between the crushing rolls. A combination of compression and shear forces created between the opposing rolls reduce the feed material to the desired product size while producing a cubicle product with minimum fines.
McLanahan’s mechanical tramp relief systems employ a spring-and-toggle mechanism that activates whenever an uncrushable object enters the crushing chamber. Once an excessive force is applied to the movable roll, the toggles break open to allow the uncrushable item to pass. The high torsion springs then close the toggles, returning the movable roll to the previous setting. The crusher continues to operate uninterrupted.
Optional features include hydraulic product adjustment, roll scrapers, automatic lubrication, wheeled support base and other custom solutions.
McLanahan Double Roll Crushers feature slower roll speeds and a larger surface area to add prolonged life to the crushing elements, resulting in less maintenance downtime and decreasing your cost per ton. Double Roll Crushers generate minimum fines while producing a cubical product.
McLanahan Double Roll Crushers are designed for safety and many years of rugged operation. Effective tramp protection against non-crushable material is provided by an automatic spring-and-toggle system. This allows a movable roll to open, pass the material and return to its original setting for continued operation. Hydraulic product size adjustment allows producers to adjust for changes in product size requirements or to compensate for roll wear.
When an uncrushable object, such as metal, roof bolts/timbers, etc., enters the crusher and the force necessary to crush this material is greater than the crushing forces of the crusher, the crusher allows the moveable roll to open and pass the tramp material and then return to its previous setting and remain in operation.
Depending on the customer’s desired product size and fines consideration, Mineral Sizers or Hammermills could be considered. The reasons people would consider a Roll Crusher over these alternative technologies include lower power requirements, less fines generation and costs.
Ratio of reduction is the ratio of the feed size to the desired product size. As an example, if the feed size is 12” and the desired product size is 3”, then the ratio of reduction is 4:1.
Black Diamond Double Roll Crushers are the most versatile and popular model of McLanahan Double Roll Crushers. Ideal for secondary and tertiary crushing applications where product requirements drop down to –¼” (6mm), Black Diamond Double Roll Crushers are most commonly used to crush clean coal or friable materials with little or no hard refuse. They are available with single or dual V-belt drive.
Heavy-Duty Double Roll Crushers are ideal for the primary, secondary and tertiary crushing of limestone, gypsum, ROM coal, etc. where higher compressive strength material is anticipated. Due to the V-belt drive design, a lower horsepower is required compared to other crushers designed for the same applications.
Shalemaster Double Roll Crushers are driven mechanically with V-belt drives and gear reducers. They offer the same durability as other McLanahan Double Roll Crushers but are designed to handle wet, sticky feeds such as soft shale, kaolin and clay. The Shalemaster’s special tooth design and differential roll speeds provide optimum performance against plugging and other problems often associated with handling sticky materials.
Double Roll Crushers have long been used in a variety of applications, including ROM feeds, clay, glass and other friable minerals.
