COPPER 913 



it at their feet, whence it is removed and disposed of as may be subsequently re- 

 quired. 



The crushing-mill has of late years been brought to a great degree of perfection, 

 and is almost universally made use of for pulverising certain descriptions of ore. For 

 an account of this apparatus, see GRINDING AND CRUSHING APPARATUS. 



Stamping-mills are less frequently employed than crushers for the reduction of 

 copper ores. At the Devon Great Consols Mines, the concentration of the crushed 

 copper ores is effected in the following manner : From the crushing-mill the stuft' 

 is carried by a stream of water into a series of revolving separating sieves, where it is 

 divided into fragments of ith inch, ^th inch, and ^th inch diameter, besides the 

 coarser particles which escape at the lower end of the sieves. The slimes flow over 

 a small water-wheel called a separator, in the buckets of which the coarser portions 

 settle, and are from thence washed out by means of jets of water into a round buddle, 

 whilst the finer particles are retained in suspension, and are carried off into a series 

 of slime-pits, where they are allowed to settle. 



The work produced by the round buddle is of three sorts ; that nearest the circum- 

 ference is the least charged with iron pyrites, or any other heavy material, but still 

 contains a certain portion of ore ; this is again buddled, when a portion of its tail is 

 tlirown away, and after submitting the remainder to a buddling operation, and sepa- 

 rating the waste, it is jigged in a fine sieve, and rendered merchantable. 



The other portions of the first buddle are rebuddled, and after separating the waste, 

 the orey matters are introduced into sizing cisterns, from which the finer particles are 

 made to flow over into a buddle, from whence a considerable portion goes directly to 

 market. That which requires further manipulation is again buddled until thoroughly 

 cleansed. The coarser portions of the stuff introduced into the sizing cisterns pass 

 downward with a current of water into the tye, and after repeated projections against 

 the stream, the orey matter is separated, leaving a residue of mundic in a nearly 

 pure state. 



The stuff falling from the lower extremities of the separating sieves is received 

 into bins and subsequently cleansed ; each of the three sizes is jigged, and in propor- 

 tion as the worthless matters are separated, they are scraped off and removed. Those 

 portions of the stuff that require further treatment are taken from the sieves, washed 

 down from behind the hutches, and treated by tyes, until all the valuable portions 

 have been extracted. 



In this way vein-stuff that originally contained but 1^ per cent, of copper is so con- 

 centrated as to afford a metallic yield of 10 per cent., whilst by means of sizing-sieves, 

 dressing-wheels, jigging-machines, and round-buddies, &c., from 40 to 50 tons of stuff 

 are elaborated per day of 9 hours, at a cost of 12s. per ton of dressed ore. 



Captain Kichards, the agent of these mines, has also introduced considerable im- 

 provements in the slime-dressing department. The proper sizing of slime is as ne- 

 cessary as in the case of rougher work, and in order to effect this, he has arranged a 

 slime-pit, which answers this purpose exceedingly well. This pit has the form of an 

 inverted cone, and receives the slimes from the slime-separator, in an equally-divided 

 stream. The surface of this apparatus being perfectly level, and the water passing 

 through it at a very slow rate, all the valuable matters are deposited at the bottom. 

 If slime be valuable in the mass, it can evidently be more economically treated by a 

 direct subdivision into fine and coarser work; since a stream of water, acting on 

 a mixture of this kind, will necessarily carry off an undue proportion of the former in 

 freeing the latter from the waste with which it is contaminated. 



The ordinary slime-pit is of a rectangular form, with vertical sides, and flat 

 bottom. The water enters it at one of the ends by a narrow channel, and leaves it at 

 the other. A strong central current is thus produced through the pit, which not only 

 carries with it a portion of valuable slime, but also produces eddies and creates cur- 

 rents towards the edges of the pit, and thus retains matters which should have been 

 rejected. The slime-pits at Devon Consols are connected with sets of Brunton's 

 machines, which are thus kept regularly supplied by means of a launder from the 

 apex of the inverted cone, through which the flow is regulated by means of a plug- 

 valve and screw. 



A waggon cistern is placed under each frame for receiving the work, which is 

 removed when necessary, and placed in a packing-kieve. This is packed by ma- 

 chinery, sot in motion by a small water-wheel. The waste resulting from this 

 operation is either entirely rejected, or partially reworked on Brunton's machines, 

 whilst the orey matters contained in the kieve are removed by a waggon to the ore- 

 house where they are discharged. 



Cornwall being destitute of coal, the whole of the copper ore which it produces is 

 sent for smelting to South Wales. 



Welsh Capper-Smelting : Furnaces. The furnaces employed are of the reverberatory 



Vol.. I. 3 N 



