96 president's address — section b. 



36 l^in. tuyeres. It is fmnislied with the usual nose, but, in addition, 

 has a special trapped feed-opening, for the introduction of the siliceous 

 ore, near one end of the cylinder. It is also provided with an axially 

 situated overflow opening, for the molten pioducts, in the other end, 

 which opening is suitably sealed against the issue of the gases and dis- 

 charges into a special settler, or forehearth, for the separation of the 

 slag and the dragged-out matte. The apparatus thus is virtually a 

 continuously working cylindrical reverberatory furnace, in which the 

 heat is generated entirely on the pneumatic principle. The siliceous 

 or semisiliceous cupriferous ore fed in flows over a previously introduced 

 bath of low-grade matte, in which the Bessemerising action is effected 

 with its assistance, the lining of magnesite remaining indifferent. The 

 20ft. traversed are said to be enough to almost complete the assimila- 

 tion of the silica contained in the ore (only 50 per cent.), so that a liquid 

 slag issues from the overflow end. The sulphides in the siliceous ore 

 are liquated out, and such silica as happens not tc unite with iron floats 

 away in the form of honeycombed shells — a pcint which is interpreted 

 as a particular advantage, since it increases the acidity of the slag 

 beyond that which the internal work automatically creates, and to 

 this extent relieves and lightens the work of assimilation. This point, 

 however, does not quite commend itself to true metallurgical feeling. 

 The original copper tenor of the preliminary matte bath is 15 per cent., 

 and it is proposed to obtain this matte by the prior smelting of heavy 

 pyrite ores with coke. In the course of the converter treatment the 

 matte is enriched until it finally is high enough to justify blowing direct 

 to copper, which can at once be done in the same vessel. It cannot be 

 said that there is anything in this method, taken as a whole, to justify 

 great expectations and which cannot be achieved, with proper skill, in 

 a more rapidly working manner by means of pyrite smelting. This 

 statement holds true for the same aggregate quantities of the various 

 original ores, including that from which the 15 per cent, matte was 

 derived, as well as for a lower blast. The only noteworthy difference 

 lies in the greater acidity of the slag, since the pyrite furnace and the 

 ordinary acid-lined converter only reach about the same degree of 

 acidity. But the increment obtained in the crude, merely mechanical 

 way involved, i.e., as incidental to the liquation of the sulphides out 

 of the siliceous ore-matrix, is hardly distinctive enough to constitute 

 a metallurgical reform. The basic converter lining does not require 

 replacement, it is true, except at long intervals, when mechanically 

 worn out ; but, as a smelting apparatus, the vessel itself, doing its 

 chemical work as it does, at the top of the matte bath, in a frothy mixture 

 of matte, ere, and slag, falls far short of the perfection of a blast-furnace 

 in the spatial co-ordinatioii of the reacting bodies. To speak historically, 

 the method is only a modern replica of Hollway's treatment of pre- 

 molten pyrites in an ordinary Bessemer converter, when, feeding it 

 with charges of pyrites and quartz, he succeeded in blowing for M 

 hours without injuring the lining to destruction and enriched a 1.8 per 

 cent, ore int ' a 50 per cent, matte. Nevertheless, he concluded that 

 the converter apparatus was unsuitable for the work, and the blast- 

 furnace more rational. 



