president's address — SECTION B. 115 



pyrite furnace in this regard) ; the ascent of the gases of combustion, 

 and the transfer of their heat to the descending masses, thus the ad- 

 vantage of the retention of a body of heat which is now wholly lost ; 

 the immediate withdrawal of the slag and the white metal after they 

 are formed, and the possibility of a constant discharge of same ; finally, 

 an easy and continuous separation of these two products by gravity, 

 ■accompanied by a lower mechanically suspended matte tenor of the 

 slags. The enriched matte or white metal itself would remain available 

 for pneumatic conversion in the usual way, without remelting. In 

 fact, since the temperature in the pyrite furnace is higher than that 

 developed in the converter, there would be no obstacle in the way of 

 a direct transfer to the vessel, subject to a passable magnitude of the 

 scale of operations. 



The scheme thus outlined is nothing more than a suggestion to 

 utilise the pyrite-smelting principle on high-grade mattes, and to 

 carry it one point further than is now customary in matte-concentra- 

 tion by that principle, by making white metal of 70 per cent, to 75 per 

 cent, copper, instead of the current grades of matte to from 35 per cent, to 

 55 per cent. It would mean a considerable curtailment of the work now 

 being done in the converter, would solve the difficulty of the linings 

 by removing it practically altogether, and would reduce the size of the 

 converting plant for the same output of metal. There is nothing 

 insuperable in the proposal, and it adheres strictly to metallurgical 

 principles of husbandry and execution, which our present method 

 violates. 



Improvement hy Superficial Oxidation — Matte-cwpellalion. — The 

 last case, the projection of the blast on to the surface of the matte, and 

 the providing of a constantly new surface, takes us constructionally 

 into a direction which has had a strong attraction for the luminaries 

 of steel, when applying their wider vision to copper-converting, and 

 dissatisfied with its heavy production of slags. Howe early (1883) {j) 

 proposed the use of a Siemens-Martin regenerative furnace for the 

 oxidation of medium-grade mattes to white metal, under the influence 

 of a powerful heated blast directed on to the bath, and with the addi- 

 tion of silicious flux, also of rich oxidised ores and refinery slags, if 

 available. The slags that formed were to be skimmed as often as neces- 

 sary, and the final cuprous sulphide was to be brought to black copper 

 in the same furnace, with continued use of the blast. Von Ehrenwerth 

 later (1895) (k) suggested the use of a basic-lined, gas-fired, tilting 

 reverberatory furnace, arranged for the use of a blast and the intro- 

 duction of silicious substances, and provided with a slag-overflow for 

 intermittent or constant use. These suggestions are modern tran- 

 scripts of the old processes of cupelling, or blowing, of impure arsenical, 

 antimonial, and leady mattes (Steintreiben, Verblasen), or the purifica- 

 tion of dirty coppers (Spleissen), to modern steel-plant apparatus ; 

 but it is doubtful if they will find an entrance. The superficial oxida- 

 tion of a bath of matte, even under the most powerfully active con- 



(j) Eng. and Min. Jl., 1883, vol. XXXV. 

 (i) Official Report on Chicago Exposition of 1893, Vienna, 1895. 



