Abstract
This hydrometallurgical iron powder process is a joint development by the Research Council of Alberta and Peace River Mining and Smelting, Ltd., in Canada, and Woodall-Duckham, Ltd., in England. A 5 tons/day pilot plant has been in operation for 2 years and work has started on a 50,000 tons/year commercial plant.
Essentially, the method consists of leaching an iron-bearing feedstock with hydrochloric acid, crystallizing the resultant liquor to pure ferrous chloride, reducing the chloride to sponge iron, and grinding the sponge to powder. The chemical properties of the product are controlled at the leaching and crystallization stages and the physical properties during reduction and grinding.
A wide range of raw materials has been tested, including pyrites, ilmenite, pickle liquor, scrap, and low-grade ores. Purification is good, and where applicable, a second product can be recovered, e.g. sulphur from pyrites and TiO2 from ilmenite. Alloy powders can be made with slight process modifications.
The variety of iron powders made by this method can meet the requirements for most applications, and the products are particularly suitable for powder rolling. High purity and good physical characteristics give excellent compressibility and green strength.
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