Crushed stone is one of the most accessible natural resources and a major basic raw material. It is used in construction, agriculture, and other industries using complex chemical and metallurgical processes. Despite the low value of its basic products, the crushed stone industry is a major contributor to and an indicator of the economic well being of the nation.
Crushed Stone Production Process
Processing activities include conveying, screening, secondary and tertiary crushing, and sizing. Screening is the single most important part of the processing cycle of crushed stone particles. A wide variety of screen types exist, and their selection is a function of the material processed and the final product required. Inclined vibratory screens are most commonly used in stationary installations, while horizontal screens are used extensively in portable plants. Large sizes of crushed stone, grizzly bars, rod decks, and heavy punched steel or plastic plates are used for screening. Woven wire, welded wire cloth, rubber, or plastic screens are used for smaller sizes. Stone is left by processing the crushed material across sizing screens where it is saturated with water, in order to remove unwanted material.
Crushing Machine for Crushed Stone
There are four common types of crushers: jaw crusher, Horizontal impact crusher, cone crusher and vertical shaft impact crusher.
A Jaw Crusher consists of a pair of jaws, which are usually made with hardened steel. During crushing, one jaw is fixed and the other is moved back and forth, driven by an eccentric wheel. The top opening of the jaws is larger than the bottom opening, which forms a tapered chute. During crushing, rock fragments are loaded via the top opening of the jaws and crushed into small fragments. Once fragments are reduced to sizes smaller than the bottom opening, they escape the bottom opening of the jaws by gravity.
Horizontal shaft impact crusher consists of hammers that are fixed to the spinning rotor. Hammers are utilized for the breaking of these rocks. Normally horizontal shaft impactor crusher is used for soft materials and materials like gypsum, phosphate, limestone and weathered shales.
The cone crusher consists of a fixed concave surface and a movable conical head. The inner cone gyrates within the fixed concave. When ores flow from top to bottom between the two surfaces, they are crushed until small enough to fall out through the gap.
In Vertival shaft impact crusher, the motor drives bearing to move, and the spindle and rotor start rotate at high speed, so the materials had entered into impeller will be jetted into crushing chamber, and then they are mutually impacted and ground with the interlining materials in the crushing chamber.