IM president's address — SECTION B. 



bustion of the iron cannot be called complete until the formation of 

 the silicate has actually taken place, and if this formation is retarded 

 by any mechanical circumstance it follows, from the general law 

 covering the subject, that the temperature must be prejudicially 

 interfered with. The temperature reached depends on the rapidity 

 of combustion, and is a function of time, as well as of the spatial 

 concentration of the substances reacting on each other for combustion. 



Another feature of the converter vessel which militates against 

 the best effect is that the indifferent products of combustion of a solid 

 form, the slags, are ordinarily allowed to remain until the iron sulphide 

 is completely oxidised, i.e., the slag is not withdrawn the moment it 

 is formed, but it is tossed about with the body of matte, and doubtless 

 mechanically interferes with the mutual contact of oxygen, iron, and 

 silica, &c. It is held that its presence is an advantage, as conserving 

 the body of heat in the boiling mass, but the depressing effect of its 

 interference with the rapidity of oxidation may more than balance 

 this good. The point here raised, it is obvious, also applies to the 

 introduction of silicious material through the nose. Even though ore- 

 bearing, its specific gravity is much less than that of the bath of matte, 

 and generally less than that of the slag formed. It will, therefore, 

 necessarily occupy an uppermost position, notwithstanding all the 

 agitation in the vessel, and its chances for assimilation with iron in 

 the entangled maze of itself, the slag and the surface layers of the 

 matte, must be relatively slight. 



Improvement of Slagging Action. — Theoretically at least, the 

 present converter vessel thus is not a very efficient apparatus for the 

 slagging off of the iron. An apparatus embodying the principles of 

 the second case, i.e., percolation against the blast, would be a marked 

 improvement. This principle would most efficiently be realised by 

 allowing the molten matte to flow through a network, or honeycombed 

 mass of silica in lumps, with the blast passing through the same inter- 

 stices between them, in the opposite direction. In effect the arrange- 

 ment would be tantamount to that of the shaft furnace, and, in par- 

 ticular, of the pyrite furnace, in which, in fact, this very same juxta- 

 position of iron sulphide, silica, and blast is the precise physical equip- 

 ment which supports its action. There cannot be any practical 

 difficulty of moment of which the experience so far gained with pyrite- 

 smelting is incapable of suggesting a solution. Oxidation would be 

 done on the " counter-current principle," and it is obvious that the 

 contact of the three substances reacting would be vastly increased, 

 and brought as near perfection as the axiom — that no two bodies can 

 occupy the same space at the same time — permits of. Incidentally, 

 all the other physical features which render the shaft furnace the 

 most perfect present-day metallurgical apparatus in point of utilisa- 

 tion of the heat generated would tend to an improved conservation of 

 heat. Such are the concentration of the combustion to a small zone, 

 or nucleus, with consonant intensity of oxidation, &c., within same ; 

 the complete absorption or assimilation of the oxygen in the air by the 

 sulphides within that zone (as demonstrated by the action of the 



