DRESSING OF ORES 



91 



between a cricket-ball and bat ; the shock thus produced being compounded from the 

 aggregate speed of tho beaters, and the speed and weight of the material meeting 

 them The projectile impetus of the flying material is thereby arrested, and a fresh 

 impulse given it in an opposite direction, to meet the beaters of the third cage 

 travelling tho reverse way, and so on in like manner with the fourth ono, when, if the 

 material is of a friable and non-fibrous nature, it is shattered by these successive blows 

 into a fine granular state, usually like that of gunpowder. 



' Tho disintegrating wheels are made of various sizes, from 3 feet 6 inches to 6 feet 

 3 inches, the capacity of the latter being nearly double that of a 4 feet 6 inches 

 machine. For pulverizing ores and vein-stones a 6 feet 3 inches size, made extra 

 strong with steel bars, shafts, and stout wrought-iron disc plates, is recommended. At 

 a silver-mine in Norway a 6 feet 3 inches machine is found to reduce from seven to 

 eight tons of ore per hour, to a size varying from to 4 millimeters, seventy to eighty 

 per cent, of the quantity being suitable for jiggers, the remainder for slime tables. 

 As a general result, the cost of reduction is reported to be one-half less than thafc 

 incidental to pans and edge-runners. 



In the following tabular statement will be found particulars of stuff reduced and 

 horse -power required : 



Dingey's Pulveriser. In this machine, fig. 669, Mr. Dingey has produced an 

 apparatus for the reduction of hard vein-stone and ore to a fine state. 



The machine is on what may be called the slab and muller principle. The opera- 

 tive parts consist of four plates revolving within a pan that rotates in the opposite 

 direction. The pan is made of iron, 6 feet in diameter, with a vertical rim in which 

 are twelve openings, each 15 inches in length by 5 inches in depth, fitted with fine 

 perforated copper plates or wire gauze. The inner or grinding surface of the pan 

 is lined with a set of plates or shoes, made of the best white iron, which can be 

 detached and replaced readily when worn out. The pan revolves from right to left, 

 or in a direction contrary to the apparent motion of the sun, borne on four friction 

 rollers fixed on the four horizontal cross-arms of the foundation frame, and it derives 

 its rotatory movement from the first-motion shaft by spur pinion and gearing on the 

 exterior of the pan. 



The horizontal shaft also drives a central pair of bevel wheels actuating a central 

 spur-wheel taking into four pinions on the vertical shafts of the revolving plates, by 

 which these plates are rotated with the sun, in a direction contrary to the pan. The 

 plates are provided with white-iron shoes, each 30 inches in diameter, and are 

 driven at a speed of 200 revolutions per minute. Thus it will be seen that by the 

 combined motions the grinding surfaces are preserved in good order from wearing in 

 grooves. 



The material to be pulverised is fed into a hopper, and thence transferred by an 

 Archimedean screw-motion to a circular launder, wherein it is subjected to the action 

 of a stream of water, entering therewith in the centre of the pan, whence it is imme- 

 diately carried under the revolving plates, ground and rapidly passed through the 

 external gratings by the centrifugal force of the stream, and there received into a 

 launder that conveys it direct to the buddies. 



The whole machine is self-contained within four standards, with top, central, 

 and bed plates and framing, so that it can be bolted down on a suitable founda- 

 tion anywhere, for immediate work. It can be constructed in light parts, easily put 

 together. 



The motive power may be hydraulic or steam ; a 10-inch single cylinder engine is 

 sufficient for working it effectively. 



This pulveriser is suited for the reduction of rough stamps'- work, and the grinding 

 of gold and silvex ores, tin roughs, skimpings, colours, clays, or earthy substances. 



