DRESSING OF ORES 



125 



708 



According to experiments made in the Stamping House of Schemnitz, where 12 

 tons are stamped in 24 hours, the 1st cistern separated from the slimes 40 per cent, 

 of the ore ; the 2nd cistern, 22 per cent. ; the 3rd cistern, 20 per cent. ; the 4th cistern, 

 12 per cent. ; together, 94 per cent, leaving a loss of 6 per cent. 



From No. 1 box every cubic foot of water flowing through gave 16 pounds of sandy 

 matter. No. 2 afforded 13 pounds of finer stuff. No. 3, 16 pounds, and No. 4 yielded 

 12 pounds per cubic foot of water. It should be remarked that the outlet o is propor- 

 tioned to the dimensions of the machine. 



Cone Classifier, jig. 707. The ore and minerals, after passing through the 

 crushing apparatus, are introduced at A, and flow through the spaces B B, passing 

 into c c. At the bottom is a circular chamber E E, with a perforated cylindrical 

 plate F. Water under pressure is supplied by the pipe G, and regulated by the 

 cock H. 



It will be seen that this apparatus consists of an external and internal cone with 

 a space between them, and that a separation of the orey matter is effected by limiting 

 the power of the water between the density of the stuff to be retained, and that which 

 is to be discharged at j j into the shoot K. 



At L the larger and denser portion of the mineral which has fallen through the 

 ascending current of water, is conveyed either to a jigging machine or some other 

 enriching apparatus. 



Fig. 708 represents a wooden cistern A, 

 having an aperture B, at the bottom, 

 about an inch diameter, which is alter- 

 nately closed and opened by means of 

 an iron plate c, fitted upon the vertical 

 shaft, to which is also fixed an iron 

 paddle D, which revolving horizontally 

 keeps the ore and water in constant 

 agitation. The tails from the various 

 buddies, as well as the stuff from the 

 coffers at the end of the strips, flow in 

 at E, and pass through a perforated 

 sizing plate F, into the cistern. The 

 rougher and heavier portions escape 

 through the hole B into a strip where it 

 is continually stirred, in order that it 

 may be evenly deposited, and at the 

 same time freed from the lighter parti- 

 cles. The overflow containing fine ore 

 passes in the launder G into catch pits, 

 from which heads and middles are taken 

 to be elaborated by means of buddies or 

 other apparatus. When this separator 

 is employed in tin dressing, it is usual 

 to divide the stuff in the strip connected 

 with the bottom of the box, into heads 

 and tails. The first is taken direct to 

 the stamps, and again pulverised with rough tin stuff; but before the tails can be 

 so treated they are re-stripped in order to get rid of extraneous matter. A plan of the 

 iron plate covering the discharge hole is shown on fig. 709. c, plate; B, discharge 

 hole. 



Wilkin's Separator. This is a ' self-acting tossing machine, by which the rough 

 particles are separated from the fine, and prepared for the inclined tables. The orey 

 matter is carried into a small cistern by a stream of water which enters at the top 

 and passes out at the opposite side, bearing the finer particles with it, whilst the 

 rougher and heavier particles escape at the bottom through a rising jet of clean water, 



