c. Cement Copper from m, n, o; this is used for precipitating the silver. d. Liquid free from Copper and Silver, in the basin (p) in which part of the iron contained in it separates as a basic salt. It is from time to time purified from its sulphate of soda by crystallisation, and then again used for lixiviation. The results of Augustin's process at Freiberg during the first six months of 1862 were as follows: By the process were treated— 1006 1 cwts. of copper matt, containing 02412 per cent of silver, and 64.98 per cent of copper. 215 cwts of cement copper, containing 0'5306 per cent of silver, and 61.48 per cent of copper. For the precipitation of silver were used— 15 cwt. of cement copper, containing 106 per cent of silver, and 86 per cent of copper. The lixiviation was effected in 84 days. In one day 11.97 cwts. of copper matt were worked. For the oxidising roasting of 5 tons of copper matt, residues, &c., were consumed 65'93 cwts. of slate coal, and 172 cubic feet of cinders. Causing an expense per cwt. of— In the desilverisation of the residues still containing silver, of such residues were worked 440 cwts. = 42.81 per cent. Five tons required for roasting 116 cwts. common salt, and 26.27 cwts. slate coal. Causing an expense per cwt. of— o'59d. for salt. 2'3d. for fuel. o'69d. for wages. Five tons consumed at the lixiviation 136 cwts. salt, and 7.78 cwts. slate coal. Costing per cwt.- o'69d. for salt. o'4d. for fuel. 1'5d. for wages. In the smelting of the residues there were worked up in For the modification smelting of raw copper slags were consumed 950 cwts. of slags. Five tons of slag and dross consumed— 30'5 cwts. of dross. 101 519 cwts. of slate coal. 1.825 cwts. of fluor spar. 31.269 cwts. of quartz. The resulting raw copper contained 0'04 per cent of silver, and 98'4 per cent of copper. The modified slag contained 3 per cent of copper. At the reducing and smelting of slags were consumed for every 5 tons of smelting mass 187.97 cwts. of slate coal. 3'44 cubic feet of cinders. 1.757 cwts. of fluor spar. Costing per cwt. A total of 3s. Iod. The total expense per I cwt. of the whole smelting mass amounted to 3s. 7d. at the extraction. o'08d. at the refining. IS. 7d. at the smelting. Yield of Metal. Of the silver contained in the mass under treatment were collected In fine silver, 79'491 per cent. In fume 1314 per cent. In cement copper o'951 per cent. products 4'980 per cent. In residues 3.976 per cent. Total loss of silver 9:288 per cent. The loss of silver in the first six months of 1862 amounted to 13'57 per cent. This amount was contained in the following proportions:-In raw copper 9.82 per cent. In copper matt 2.81 per cent. The copper was obtained from the substances under treatment as follows: In raw copper 72:37 per cent. In cement copper o'271 per cent. In copper matt 19.833 per cent. In smoke o 396 per cent. In marketable intermediate products 1'044 per cent. Loss of copper 3.23 per cent. Augustin's Process for the Treatment of Speiss. The treatment of speiss is generally very difficult, on account of antimony and arsenic contained in it, but it has occasionally given satisfactory results,-at the Stephanshütte, in Hungary, for instance. Ferientsik* extracted the silver completely, and 87 per cent of the copper from argentiferous speiss. The hot solution of common salt employed for lixiviating the silver contained some chloride of iron, and the residues contained 4 per cent of copper. A loss of about 4 per cent of silver took place when treating this speiss by the amalgamation process. The argentiferous speiss, containing 44 per cent of antimony, 27 per cent of copper, 20 per cent of iron, 3 per cent of sulphur, 2 per cent of arsenic, bismuth, cobalt, nickel, silver, and gold (only o'0032), is roasted at a low temperature in quantities of 9 cwts. for 5 hours on the upper hearth of a double roasting furnace, and afterwards on the lower hearth for the same time; it is then lixiviated. The residues are now roasted for about 5 hours in admixture with some iron pyrites or matt, and again lixiviated. The resulting residues rich in antimony, and containing from 2 to 4 per cent of copper, are smelted with from 30 to 50 per cent of pyrites for the production of copper matt and a speiss rich in antimony; if the copper matt contains about 7 per cent of copper it is added to the speiss while roasting. The extraction of copper will be imperfect if the speiss has only been once roasted. * Bericht üb. d. 2, Versammlung v. B. u. H. in Wien., 1862, pp. 25, 82. B. u. h. Ztg., 1864, p. 323. Augustin's Process for the Treatment of Black Copper. Black copper suitable for this treatment must be nearly free from lead, and must contain a little antimony, and not too much copper; black copper must also contain these substances to make it fit for the amalgamation process. When the copper contains much lead, it requires a purifying smelting, as well as a lixiviation of the chloride of lead which will be formed at the chlorinating roasting before the complete chlorination of the silver. These very expensive operations may be dispensed with if it is possible to mix plumbiferous black copper with a greater quantity of black copper free from lead; this is done at Tajova* when argentiferous copper ores are smelted with an addition of 80 per cent of lime. The mixture then contains 12 per cent of copper, and o'045 per cent of silver, and produces 24 per cent of matt, containing 45 per cent of copper, and o'14 per cent of silver, besides 3 or 4 per cent of antimonial speiss containing 80 per cent of copper and 0'25 per cent of silver. The matt is now roasted 11 or 12 times, and smelted in admixture with 10 or 12 per cent of raw speiss, producing from 40 to 43 per cent of black copper, containing from 80 to 85 per cent of copper and 0'25 to o 26 lb. of silver, besides 20 per cent of matt. An analysis of such black copper free from lead shows the following composition : B. u. h. Ztg., 1859. p. 286; 1861, p. 326; 1862, pp. 18, 39; 1864, p. These are mixed together in a proper proportion, causing the loss of silver at its extraction to amount to only 5 per cent, instead of the loss of 17 per cent occasioned when purifying the plumbiferous copper. In order to reduce the black copper to a fine state of division, it is melted, ladled out in a pasty state, and spread upon a cold cast-iron plate, where it is divided as much as possible by means of a wooden mallet, then pounded, ground, and sifted; 7 cwts. may be prepared in about 12 hours. The powdered black copper is next mixed in the proportion of 100 lbs. of plumbiferous copper to 300 lbs. of copper free from lead, and roasted in a double roasting furnace, with an addition of about 10 per cent of powdered salt. It is kept for about 5 hours on the upper hearth of the furnace at a red heat, during which time it is repeatedly turned. It is afterwards roasted for about two hours on the lower hearth, at a higher temperature, chiefly in order to decompose the antimonial salts. If the mass becomes darker at this roasting period, some coal or wood rubbish is added, raising the temperature so much that no new fuel need be put on the grate till within about 1 hours of the end of the operation. The length and the temperature of the roasting depend on the quality of the roasting material, and must be determined by minute observations of the roasting process, as well as by a combination of the results obtained by the roasting and extraction process. After cooling, the roasting mass is sifted, and the fine powder which passes through the sieve is submitted to the extraction process, while the powder remaining on the sieve is ground and roasted again. The roasting mass must be moistened to prevent any loss during sifting. The roasting mass is lixiviated in a similar apparatus, and in the same manner as adopted at Freiberg, described at page 368. The resulting residues must not contain more than o'009 per cent of silver; should they contain more they are kept for some time in a very warm place, where they will become more perfectly chlorinated by themselves, when they are to be again lixiviated. |