president's address — SECTION B. 117 



arsenical middle-products, with from 26 per cent, to 52 per cent, of 

 copper and 16 per cent, to 35 per cent, of lead, are subjected to a blast 

 of 12ozs. in a modernised side and bottom water-cooled reverberatory 

 furnace, of small dimensions (60 square feet hearth), and with a re- 

 movable roof and an acid bottom, which stands from 12 to 18 charges. 

 The exposure lasts 56 hours for 13 tons of speisse, and consists of 

 alternating calcinations and fusions, and yields a product of 90 per 

 cent, purity in copper, with a coal consumption of 28 per cent, to 30 

 per cent. At Brixlegg (n) a similar method is in vogue for arsenical 

 and antimonial copper material, carrying 46 per cent, copper and 

 29 per cent, lead, after liquation. A peat-burning, gas-fired rever- 

 beratory furnace is employed (75 square feet hearth), lined with mag- 

 nesite, and provided with an air blast. The latter is put on after 

 complete fusion and the first slamming, quartz sand being added to 

 slag the oxides formed, the slags assaying 20 per cent, to 50 per cent, 

 in copper. The duration is 44 hours, in which time 9 . 5 tons of speisse 

 are charged. The product is metal of 95 per cent, copper. As 

 remarked, these working schemes would seem to belong to an inferior 

 category of pneumatic work, but if, as is the case at Oker, they are 

 sufficiently perfect to have warranted the intentional production of 

 speissy lead-copper mattes for the purpose of purifying the ordinary 

 copper-work, they suggest the question whether they cannot be re- 

 placed by the proper converter process for the beneficiation of this 

 commonly exceedingly unwelcome material. 



Finally, the most recent rival of the converter process is a type 

 of proposal belonging to the superficial oxidation class, which is 

 ingenious and modern enough to harbor a certain amount of promise. 

 It consists of the projection of a mixture of compressed air, steam, 

 sand, and copper oxides, through numerous tuyeres, on to the surface 

 of a large bath of medium-grade matte in a reverberatory furnace. 

 This blast of materials causes a vivid oxidation at the point of impact, 

 supported by the oxides blown in, and accompanied by the (expected) 

 removal of volatile elements by the steam, in addition to the usual 

 scorification of the iron, &c., without corroding either the walls or the 

 bottom. An advantage is that the blast constantly impinges on a 

 clear surface, and that there is no mixing up of the furnace contents, 

 as in the converter. The supernatant layer of slag can be blown in 

 the direction of a continuous overflow. It is claimed that the treat- 

 ment is applicable to much larger quantities than are customary in 

 the converter, and that 50 tons of matte can be slagged in six hours. 

 The resulting white metal can be brought to copper in the same furnace, 

 with blast, if desired. The suggestion has an up-to-date pneumatic 

 ring about it, which will cause further developments along this line to 

 be watched with interest. (o) 



Bessemer Principle Applied to Ores. — So far, the theme of the treat- 

 ment of copper mattes. It yet remains to mention the important 

 topic of the application of the forced pneumatic principle to sulphide 



(n) Kroupa, Oesterr. Zeitschr. f. B. u. H., 1906, vol. LIV., Nos. 6 and 7. 

 (o) " Reacteur " process of Thofehrn and St. Seine, 1905-6. 



