A rock grappler is a claw shaped device used for picking up boulders. The grasping mechanism of a grappler is generally activated by a pneumatic or hydraulic cylinder, as shown in Figure 17. The cylinder is connected to each half of the claw and when activated forces the claw shut. Grapplers are used to remove … Read more
The rock hammering method of boulder breaking is a process of hammering the boulder by either a hydraulic or pneumatic hammer until the boulder breaks. The hammer is usually mounted on a boom. The motor, hydraulic pump, and oil reservoir are usually located near the boom. Figure 14 shows a typical hammer installation. The advantages … Read more
Boulders can be broken up using either explosives or mechanical methods which can be implemented in many ways. Handling boulders hung up in crushers is inherently inefficient for the overall operation, and the techniques in handling them each have their own advantages and disadvantages. Table 4 shows a comparison of explosive boulder breaking techniques. When … Read more
Several products have come on the market in recent years that improve the safety of secondary blasting operations. The most significant of these are binary explosives, exploding bridgewire electric blasting caps, and nonelectric systems. Binary Explosives Binary explosives are two nonexplosive materials that become cap sensitive, high energy explosives when mixed. One part can be … Read more
In mining and quarryinq, the mineral commodity as present in the ground may be composed of rock blocks that must be reduced in size, to suit market requirements. The rock in place will be blasted, loosened, and then hauled away to the first processing step-size reduction. As delivered from the blasting area the rocks will … Read more
The flotation section starts with a bulk concentrate float for lead and copper using four rows of eleven cells each as roughers and scavengers. The froth taken off the roughers is then pumped to a two stage cleaner circuit. Scavenger froth and cleaner tails are returned back to the head of the rougher circuit. Froth … Read more
The trend in the design of fine crushing plants is in the direction of the horizontal arrangement with all crushers on a single floor. Conveyors from the coarse ore bin or stockpile, feed the scalping screens which are usually double decked. When the feed to the fine crushing plant contains less than 15 percent passing … Read more
Comprehensive underground hard rock mining studies pointed out that significant reductions in ore handling costs could be attained if portable, low headroom, hard rock crushers were available to permit economical belt haulage from temporary locations close to production sites. Prompted by these reports a specific “Application Study of Portable Jaw Crusher” was initiated to quantify … Read more
Increasing capacity of bulk material handling systems creates difficult problems for accurate in-line material weight measurements. At the same time increasing system complexity and growing user demands call for more measurements. Precision in-line weight measurements for bulk materials are usually accomplished by application of conveyor belt scales. Belt scale accuracies listed by scale vendors are … Read more
The crushing plant simulator was utilized to evaluate the influence of major variables on the following responses: plant reduction ratio , weight % of -½ inch material in screen undersize, circulating load ratio and secondary screen efficiency. Variables manipulated were: weight % of +1 inch material in secondary crusher feed (73.3 to 92.9%), secondary crusher … Read more