president's address — SECTION B. Ill 



accurate account of all products except fluedust, for the deposi- 

 tion of which there were no adequate facilities, the deficiency was 

 11.26 per cent, of the copper. The ores were not argentiferous, hence 

 the silver question was not touched. More damaging to the pneumatic 

 method still are the results of recently made laboratory experiments 

 by Giinther, 1905, (A) conducted with suitable apparatus and with all 

 scientific care and precision. The quantities of matte used were 50 

 kilos to 90 kilos, divided into several smaller parcels, which were blown 

 under pressures ranging from 21bs. to Tibs, per square inch. After 

 slagging, the two products were poured, and the united white metal 

 was then blown to blister. The first period of blowing showed losses 

 of 1.77 per cent, copper and 2.78 per cent, silver : and a duplicate, 

 0.37 per cent, copper, 1.59 per cent, silver. The blowT.ng of the white 

 metal (71 per cent, to 77 per cent.), however, gave disastrous-looking 

 figures, viz., respectively, 20.14 per cent, and 21.11 per cent, loss in 

 copper, and 22.12 per cent, and 23.42 per cent, loss in silver. The 

 mattes were from Mansfield, where they are not specially impure — 

 chief impurity, 3.7 per cent, to 7.4 per cent. zinc. There is no doubt 

 that losses as grave as these are not characteristic of copper-converting 

 on a proper scale, for they far transcend even the aggregate losses 

 sustained at the present day in the whole smelting procedure from 

 rd,w ore into blister copper. 



It is obvious that, provided the operation is conducted on reason- 

 ably careful lines, the pneumatic treatment of mattes cannot lead to 

 any other losses than, first, that suffered through the non-condensation 

 of the volatile products, i.e., the chemically or mechanically entrained 

 elements in the fumes and gases ; and, second, that which is encountered 

 in the subsequent treatment of the slags, old linings, fluedust, vessel 

 refuse, and similar middle products, in the prefatory smelting process. 

 There need be no other source of leakage of a palpable nature. As far 

 a,s the entrainment of silver and gold is concerned, the decrement 

 incurred through non-condensible elements and compounds, which 

 cannot be recovered even with the most perfect condensing system, 

 must, however, be exceedingly slight. Again, the losses incident to 

 the passage of the middle-products through the antecedent operations, 

 etc., will be but inconsiderable when reckoned on the original contents 

 of the matte converted. 



The metallurgical records of Mount Lyell, which, it may be asserted, 

 are practically unique, for copper-smelting plants, in the painstaking 

 care and attention with which the metallic balance-sheet is kept, afford 

 a means of determining the copper and precious metal losses with 

 exemplary closeness, and for one period out of many, covering the 

 production of 4.000 tons of blister, are as follows. Crediting the full 

 contents of all the middle-products made by the converter in addition 

 to its direct metal output, the abstraction of copper through the channels 

 that cannot be further controlled amounts to 1.17 per cent, of the 

 copper in the matte. If the losses incident to the resmelting of the 

 middle-products in the ore blast-furnaces are added, then the total 

 {h) Metcdhtrgie, vol. II., No. 22. 



