Journal - South African Institute of Mining and Metallurgy . ugh the ore feed ,that which does not strike the heads or over the dies and lands on the bottom ofthe screen frames or chuck blocks, thereby causinga back-wash which has a tendency to keep backcrushing, by checking the free discharge. Water let in at the back of the box, level withthe top of the dies, as in trial No. VI., forces theuncrushed rock to bank up against the screens and causes the shoes to drop on ba rther, the watei inlets will frequentlywith small rock If water be let in through li\epipes, two at each
Journal - South African Institute of Mining and Metallurgy . ugh the ore feed ,that which does not strike the heads or over the dies and lands on the bottom ofthe screen frames or chuck blocks, thereby causinga back-wash which has a tendency to keep backcrushing, by checking the free discharge. Water let in at the back of the box, level withthe top of the dies, as in trial No. VI., forces theuncrushed rock to bank up against the screens and causes the shoes to drop on ba rther, the watei inlets will frequentlywith small rock If water be let in through li\epipes, two at each side of the fe< d chut indei the Feed chut deliver the hack plate vertically and strike theof the dies at an angle of about 50 iwn in Bketch, then the water striking the back plate,comes off on to the dies in astrong enough ? to the •-, while having sufficient foi ry all crush* iid -lime- to the helped out with the splash »ping of tlie -tamp-. This water strik an .it _ .11 follow | wn as it wears. This fact is ol especially where deep mortar I ~^M. - JP FIG : -SKETCH SHOWING VARIOUS METHODS OISUPPLYING WATER I advocate the style of water feed as in IIL. not only from resultexperiment-, hut from close observation of opera-tion on a large scale. By packing up the dies with false bottoms anddifferent sized chuck blocks (as the dieswear down) an even crushing throughout the lifeof the dies can be maintained. Another methodto attain the same end is to use Mr. Chews falsedies. But to change false dies and false bottoms 374 The Journal of The Chemical, Metallurgical and Mining Society of South Africa. June 1908 takes up time and c ppages and is costly in spares. I take it that all niillmen areendeavouring to crush a large quantity of rock,and to crush it cheaply in the shortest space oftime. I make the above fact my excuse forintroducing the following sketch of a shallowfront mortar box. With such a box the dies ranrn down to the flange which holds them inposition and
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Keywords: ., bookcentury1800, booksubjectmetall, booksubjectmineralindustries
