VIRIDIS provides robust and efficient machine that perform size reduction of solid particles which comply with clients’ requirements.
Particle size reduction machine includes:
(Click the equipment below to read respective working mechanisms.)
The ball mill is used for the grinding of a wide range of material, including coal, pigments and felspar for pottery, and it copes with feed up to about 50mm size. In its simplest form, the ball mill consists of a rotating hollow cylinder, partially filled with balls, with its axis either horizontal or at small angle to the horizontal. The material to be ground may be fed in through a hollow trunnion at one end and the product leaves through a similar trunnion at the other end. The efficiency of grinding increases with hold up in mill, until the voids between the balls are filled. Further increase in the quantity then lowers the efficiency.
Semi-autogenous Grinder (SAG) utilizes grinding balls like a ball mill. A SAG mill is usually a primary or first stage in the grinding process. SAG mills are characterized by their large diameter and short length as compared to ball mills. SAG mills are primarily used at gold, copper and platinum mines with applications also in the lead, zinc, silver, alumina and nickel industries. SAG uses lifting plates along the interior of the drum, which lift material throughout the rotations, causing them to fall onto one another to promote crushing.
Mining operations use crushers, commonly classified by the degree to which they fragment the starting material, with primary and secondary crushers handling coarse materials, and tertiary and quaternary crushers reducing ore particles to finer gradations. Each crusher is designed to work with a certain maximum size of raw material, and often delivers its output to a screening machine which sorts and directs the product for further processing. Typically, crushing stages are followed by milling stages if the materials need to be further reduced.
Typical commonly used crushers:
· Jaw Crusher
Jaw Crusher can be used in mining, metallurgical industry, construction, road and railway building, chemistry, etc. A jaw or toggle crusher consists of a set of vertical jaws, one jaw being fixed and the other being moved back and forth relative to it by a cam or pitman mechanism. The jaws are farther apart at the top than at the bottom, forming a tapered chute so that the material is crushed progressively smaller and smaller as it travels downward until it is small enough to escape from the bottom opening. In the Blake or jaw crusher the moveable jaw is pivoted at top. The greatest amount of motion is at the bottom which means it has the little tendency to choke.
· Cone Crusher
Cone crushers are commonly used for secondary, tertiary and quaternary crushing duties. Cone crusher consists of an inverted cone (the bowl or concave) that sits over a conical head (refer to figure). The feed inlet is at the apex of the crusher; the crushing chamber (or cavity) tapers from the feed inlet to the product discharge outlet. The head is seated on a vertical shaft that is driven by spiral bevel gears connected to a counter shaft. This causes the head to move in an elliptical path around the main shaft; viewed in cross-section the crushing action is similar to that of a jaw crusher.
· Gyratory Crusher
Gyratory crushers are similar to cone crushers; they are frequently used in large-throughput primary crushing roles. Typically, they have larger capacities (up to 8000 tph) compared to jaw crushers (up to 1500 tph). Gyratory operate at a slower speed than cone crushers, typically in the range 85 to 105 rpm. They do not require feed mechanisms and are usually fed direct from the back of a dump truck. The available feed opening area of a gyratory crusher is approximately three times greater than that of a jaw crusher of a similar gape; the gyratory has a higher capacity. The most commonly-used type is a supported-shaft gyratory crusher; the main shaft is suspended from an overhead spider. The angle of the mantle is steeper than that used in a cone crusher and this causes gyratory crushers to have a smaller throw. This affects the flow of material and improves the particle shape as material is struck more frequently in the crusher cavity.
2 rolls, one in adjustable bearings, rotate in opposite directions and the clearance between them can be adjusted according to the size of feed and the required size of product. Both rolls may be driven, or one directly and the other by friction with the solids. The crushing rolls, which may vary from a few cm up to about 1.2m in diameter, are suitable for effecting a small size reduction ratio, 4:1 in a single operation, and it is therefore common to employ a number of pairs of rolls in series, one above the other. The capacity is usually between one-tenth and one-third of that calculated on the assumption that a continuous ribbon of the material forms between the rolls.