76 president's address — section b. 



2. The production of black copper (of 95 per cent, copper) with 

 the apphcation of highly compressed air, though perfectly feasible, is 

 likely to be unprofitable, partly on account of a marked copper wastage 

 and partly on account of the formation of mere accretions of metallic 

 copper on the sides of the vessel {i.e., the copper thus forming scrap, 

 instead of collecting in a body). 



3. Notwithstanding the above, the suggestion of M. Semennikow 

 is deserving of the greatest attention, and may be of great utility in 

 practice if applied to the working up of a copper matte under the follow- 

 ing conditions :— 



a. Copper matte from the blast-furnace should be run into the 



Bessemer retort immediately after tapping, to save remelting ; 



h. The Bessemer operation should only be carried to the stage at 



which a product of from 73 per cent, to 80 per cent, of copper 



is produced, approximately expressed by the formula CugS 



+ 0.12FeS, up to pure CuoS. Owing to the circumstance 



that the formation of this product is accompanied by special 



external phenomena of a reliable and distinctive nature, 



there is no difficulty in conducting this particular method in a 



Bessemer vessel of any dimensions whatsoever. 



On the subject of the losses, the aiithors state that the copper 



waste, on the whole, is negligible, if the process is thus terminated at 



the white metal stage, and it is likely to be below 10 per cent., the slags 



themselves carrying but 0.5 to 2 per cent, copper, the balance being 



in suspended matte. And, provided the blowing is stopped soon after 



the appearance of the " green " flame, even the mechanical loss is not 



serious. They were aware that this entrainment was not a true loss, 



inasmuch as the converter slags are always available for return to the 



smelting operations which precede the pneumatic treatment. 



c. The white metal, or regulus, above referred to, the writers 

 recommend bringing up to black copper in the ordinary way 

 in a roaster furnace provided with a number of tuyeres for 

 the use of an air blast. 



The ordinary Bogoslowsk scheme of matte treatment was very 

 simple, and consisted only of three steps, i.e., calcination of the coarse 

 metal, roasting of same to 95 per cent, black copper, and refining of 

 this to 98 per cent, blister. The new scheme, however, would have 

 curtailed this still further, thus : enrichment of the matte in the con- 

 verter by means of an air blast, and bringing the product, white metal, 

 up to blister, &c., in one continuous operation in the reverberatory 

 furnace. 



On the economical side the advantages of the Bessemerising, in- 

 cluding the subsequent proposal for fining, which took one day, are 

 stated as follows : — 



1. A gain in time : at Bogoslowsk the concentration of 450 pud 

 {16,2001bs.) of matte (31.5 per cent, copper) into 95 per cent, black 

 copper required four and a half days ; the new method would bring 

 the same quantity of matte up to white metal in three blows of one 



