Aggregate Crushing plant,Aggregate Crushing Equipment for Sale

Crushing is the critical first step in the production process, the industry is moving toward larger primary crushers as production capacity objectives increase.

The proper selection of the primary crushers in an aggregate plant is extremely important. After the original reduction of material in the quarry shot, the primary crushing stage is the most economical segment of the aggregate plant in which to make material reduction. While for years the primary was merely looked upon as a preparation for further crushing, today the primary machine is considered for its contribution to the overall production of various sizes, as well as the product quality created.

The two basic types of primary crushers are compression-type machines; in this case, a primary jaw crusher or gyratory crusher, and the impact type, such as the Andreas style or the single-impeller impact breakers. A jaw crusher being a compression-type crusher, reduces material as it advances downward into the crushing chamber and is compressed and fractured. Each particle or rock is crushed an average of two to two and one-half times as it passes through the jaw with a reduction ratio of approximately six to one. Normally fines are scalped out in the feed, via a grizzly feeder or screen, prior to entering the jaw. With a gyratory crusher we do not remove the fines and allow some material on material reduction in the long primary chamber. Gyratory installations are taller and heavier and not suitable for any type of mobile operation.

Generally, the jaw crusher in shot limestone will accept a maximum feed size of 80 percent to 90 percent of the tip-to-tip dimension on the jaw. In an impact crusher, the feed opening is no more than a cut out in the housing with a chain curtain permitting the rock to enter high above the rotating impeller bars for sound impacting.

Unlike jaw, impact-crusher manufacturers have different designations for sizes. It is not as easy to know the size of one machine versus the other. Focusing on width of the machine, the feed opening (height and width), and rotor diameter is the best way to compare one machine to another. In impact crushers, the maximum recommended feed size would be approximately 80 percent to 90 percent of the narrowest dimension into the chamber, be it vertical or width-wise.