218 THE ROYAL SOCIETY OF CANADA 



blast furnace smelting, is too costly for use; but the cost of smelting 

 these ores in electric furnaces is too high for satisfactory commercial 

 operation. The question naturally arises whether any improvement can 

 be made in the furnace whereby any considerable economy can be 

 effected. 



The possibility of increased economy can be studied from two 

 points of view. The first of these is the actual efficiency of the electric 

 furnace, and the second is the wider consideration of the whole prob- 

 lem of the reduction of iron ores. The electric smelting furnace is 

 wasteful, as regards fuel and electrical energy, because the gaseous 

 product of the reduction of the ore is largely carbon monoxide instead 

 of carbon dioxide. In the Swedish furnace, which is the most efficient 

 type, the carbon monoxide is utilized to some extent for the reduction 

 of the ore, but even in this furnace only one-fourth of this gas is util- 

 ized and the gas that still goes to waste contains as much potential 

 energy as the net heat requirements of the furnace, or about three- 

 fourths that of the electric power supply. It follows therefore that if 

 the carbon monoxide could be completely utilized, the consumption of 

 fuel and of electric energy would both be very materially reduced. 

 So far, however, no satisfactory way of doing this has been arrived at. 



The problem can be viewed, however, from a different and a wider 

 point of view. In smelting iron ores in the electric furnace, a large 

 amount of electric energy is needed — about 0-4 E.H.P. 3'ear per ton 

 of pig iron — and this is the most serious item of cost in the operation. 

 As the fusion of the pig iron and the slag only accounts for one-fourth 

 of this amount, it is clear that by far the largest item in electric 

 smelting is the energy requirement of the chemical reduction of the 

 ore. So long ago as 1872 Sir Lothian Bell showed that the reduction 

 of iron ores to the metallic state took place in the shaft of the blast 

 furnace at temperatures considerably below the fusion point of the 

 ore or the resulting iron or slag. This circumstance renders it prob- 

 able that it will be more economical to carry out the reduction of the 

 ore by means of fuel-heat, at moderate temperatures, and to leave for 

 the electric furnace the smaller but more appropriate task of melting 

 the metallic product and of reducing from the silica in the ore the 

 required amount of silicon. 



The smelting of iron ores in the blast furnace has been in operation 

 for hundreds of years, and iron ores have been reduced in the solid 

 condition to the so-called "iron sponge" for a number of years, but 

 we have not as yet in metallurgical literature any definite information 

 with regard to the speed and completeness with which iron ores can 

 be reduced to the metallic state at various temperatures and with 



