d. Copper Matt Concentration Process.-The matt for concentrating in reverberatory furnaces contained on an average At Halsbrücke. 0.2509 lb. silver. 47'04 ,, copper. At Mulden. o'1974 lb. silver. 40'74 ,, copper. Five tons of copper matt for the mixture consisted of— One cwt. of copper matt consumed in the smelting process o'gr cwt. slate coal. I'13 cwt. slate coal. The smelting cost per 1 cwt. of copper matt was— The mixture produced, of slags which were thrown aside At Halsbrücke. 60.36 per cent. At Mulden. 62.29 per cent. The total smelting cost per I cwt. of matt was— e. 5'390d. for ores and flux ores. 0.489d.,, fluxes. 13'142d. fuel. 3.817d. labour. IS. 11:484d. Smelting of the Slags obtained by Concentrating Lead and Copper Matt.-Five tons of slags were smelted together with The total cost for ore and flux ores amounted to 38. 2'595d. 78. 4'136d. The metals, at the lead matt smelting, copper matt concentration process, and the slag smelting process, were contained in the mixture as follows: At Halsbrücke. 63.75 per cent in intermediate : At Mulden. Silver: products. 84.11 per cent in intermediate 36.25 in ore and lead ore. 15.89 in ore and lead ore. Desilverising Matt by Lead Products and Copper. The processes for this operation consist of smelting argentiferous copper matt with argentiferous black copper and lead products. The copper matt may be produced either from real copper ores by raw smelting, or by a repeated desilverising of cupriferous silver ores by means of lead. In these processes the liberated lead and the copper will together decompose the sulphide of silver contained in the matt. The extracted silver enters into combination with lead, and there. result a matt richer in copper and poorer in silver, and a raw lead richer in silver. The copper also partly decomposes the sulphide of lead contained in the matt.* When the black copper contains silver it is likewise extracted by the lead. When too much copper is added the whole will not enter into the matt, but part will combine with the lead; and if lead is not added in excess to the sulphide of silver, the copper will alloy with the silver, and also form argentiferous copper matt. If all the circumstances are suitable, these processes will effect a more perfect extraction of the silver, and a production of purer black copper than is possible by a simple liquation of black copper; but they are amongst the most complicated of metallurgical operations. The desilverised refined copper always retains a considerable amount of silver; for instance, copper of 5 ozs. retains about oz. of silver, equal to 10 per * KARSTEN'S Metallurgie, v., 476. ERDMANN'S Journal für pr. Chem., ii., 133. cent of the whole silver originally present, and there is also a considerable loss of lead and copper. On account of their disadvantages these processes are sometimes replaced by a process in the wet way (treatment of copper by sulphuric acid). Smelting with Black Copper.-This process was introduced into Upper Hungary, Nagybanya, by Schweitzer, in 1832, for the working of real auriferous silver ores, of argentiferous and auriferous pyrites, of argentiferous copper ores, and lead products containing a variable amount of gold and silver. Whether the application of this process is advantageous or not depends on the proportion of the matt to the black copper resulting from the smelting. If matt is present in excess, the extraction of the silver will be too incomplete; a deficiency of matt, on the other hand, will cause the copper to combine with the raw lead. Abdarr Process.-This is a liquation process combined with raw smelting and fusion with lead. It allows a more perfect extraction of the silver, causes less loss of copper, and the refined copper produced is of a better quality than that resulting from the common liquation process. It resembles the copper liquation process in treating argentiferous matt with lead products and black copper. This process is the most complicated of all metallurgical processes, and is only applicable to argentiferous copper ores, and not to cupriferous silver ores, which do not contain sufficient copper to collect the silver. The process is in use at Szalathna, in Siebenbürgen, and at Brixlegg,* in Tyrol, for the working of copper ores associated with baryta, quartz, and calc spar. 3. Lead Process with Argentiferous Speiss (Regulus). Argentiferous speiss resulting from lead, silver, and copper smelting processes, is desilverised by a fusion with lead, by amalgamation in the wet way, or by a treatment with solution of common salt or diluted sulphuric acid. At Freibergt lead and cupriferous speiss, resulting from * Oesterr. Ztschr., 1853, p. 221. + PLATTNER and RICHTER'S Vorlesungen, ii., 352. B. u. h. Ztg., 1864, p. 59. the different smeltings of lead ore, lead and copper matts, as well as from the concentration processes of lead and copper matt, containing 0'4 to 0'5 per cent of silver and 2'5 per cent of nickel and cobalt, is roasted and smelted together with 50 per cent of lead hearth ends, 150 per cent of baryta slags from the copper matt concentration (see Copper), and 10 per cent of sulphate of baryta, for the production of raw lead, copper matt, and speiss poor in silver, and containing 12 or 13 per cent of nickel and cobalt. The speiss is then without any re-roasting desilverised 2 or 3 times by a treatment with lead products, slag from the cupelling process, and 10 per cent of sulphate of baryta, till at last a speiss results containing o'03 lb. of silver, from 15 to 18 per cent of copper, and from 15 to 18 per cent of nickel. This speiss is further concentrated in a reverberatory furnace (see Nickel); efforts were made to desilverise the speiss after calcination in a reverberatory furnace by fusing and stirring it with 1 times. its weight of lead, when there resulted raw lead containing o'02 lb. of silver, copper matt, and a speiss containing matt and o‘02 lb. of silver. 4. Lead Process with Argentiferous Black Copper. In this process the two following cases must be taken into consideration: a. Copper Rich in Silver may be cupelled directly with 16 times the quantity of lead, but, according to Wehrle,* causing a loss of 12 per cent of lead and I per cent of silver, and therefore this mode is only applicable to copper rich in silver and in gold; it is also advisable to add the copper, in quantities not exceeding 6 per cent, to rich lead when cupelling it. The resulting litharge rich in copper, must be reduced, if possible, together with other argentiferous and cupriferous residues, and the resulting alloy liquated. This process is seldom used. b. Black Copper poor in Silver is submitted to the liquation process. If such a copper is smelted together with lead in a certain proportion, a mixture is formed after * Oester. Ztschr., 1857, p. 281. |