Section III, 1922 [175] Trans. R.S.C. 



The Reduction of Iron Ores hy Carbon Monoxide 



By Alfred Stansfield, D.Sc, F. R.S.C, and Donald R. Harrison, 



M.Sc. 



(Read May Meeting, 1922) 



The research described in this paper^ is a preliminary study of 

 the rate at which hematite and magnetite ores can be reduced to the 

 metallic state by heating the crushed ore in a stream of carbon 

 monoxide to temperatures between 700°C. and 950°C. One ore 

 employed was a pure dense hematite from Lake Superior containing 

 68 per cent, of iron and 2.9 per cent, of silica and alumina. The 

 other was a magnetically concentrated magnetite from Hull, Que., 

 containing 57 per cent, of iron and 15.7 per cent, of insoluble matter. 

 Each ore was crushed and passed through a sieve of 30 meshes to the 

 linear inch, the finer particles passing through a sieve with 40 meshes 

 to the inch, were rejected. The ore particles employed were thus 

 nearly uniform in size and measured about 0.5 mm. in diameter. 

 The ore, spread out in a boat, was heated in a silica tube in an electric 

 tube-furnace, and a stream of carbon monoxide was passed steadily 

 over the ore. The quantity of ore used was 2 . 5 grams in most of the 

 experiments, this amount, which was needed for the chemical analyses, 

 formed a layer of 2 mm. or about 5 grains of ore in depth. 



When the furnace had been heated to the desired temperature 

 carbon monoxide was admitted to one end of the silica tube. The 

 gas leaving the other end of the tube was measured and analyzed for 

 carbon dioxide. The extent to which the ore had been reduced to the 

 metallic state was found by the loss of weight of the ore in the boat, 

 by analysis of the reduced ore and by the amount of carbon dioxide 

 formed. These independent methods were found to check very well 

 and it was therefore possible to calculate the amount of oxygen 

 remaining in the ore, at each stage, from the amount of carbon 

 dioxide formed up to that point. 



A chart was plotted for each experiment, showing on a time basis 

 the amount of oxygen in the ore and the amount of carbon dioxide in 

 the gas. As an example of these. Fig. 1 shows the reduction of the 

 hematite ore at 850°C. in a stream of 1500 c.c. per hour of carbon 

 monoxide. The "percentage reduction" referred to in the chart 

 represents the loss of oxygen from the ore expressed as a percentage of 

 the amount originally present. 



^The experiments were made by D. R. Harrison as thesis for his M.Sc. degree. 



