Direct Reduction of Iron ore to yield usable Steel

Abstract

A process of production steel directly from Indian iron ore has been investigated, with a view to its application on a cottage industry scale. In the process developed, crushed iron ore, dried and ground preferably finer than -70 mesh, is packed in a paper tube and embedded in solid charcoal in a sealed steel canister. The canister is heated to the reduction temperature and then raised to a sintering temperature of the order of 1100° c for several hours depending on the carbon content required in the steel. A fairly compact steel bar is obtained after reduction which lends itself readily to hot working. Optimum conditions for obtaining full reduction and the desired density in the compact were determined by passing carbon monoxide gas over pellets made from ground iron ore of different mesh sizes. Iron ores from different Indian localities were examined. It was observed that each ore possessed different characteristics in respect of shrinkages subsequent swelling, percentages loss in weight and reducibility. when the reduction was carried out with charcoal, and coarse and fine mesh sizes were together, the resultant density of the reduced product was higher when what obtained when coal/coarse or fine mesh size was individually treated in the former case, the product showed freedom from surface cracking. Variations in sintering conditions had pronounced effects on the density of the product obtained, for all ores. Reduction at 900° c. High sintering temperature such as 1200 ° c gave low density products. Addition of mill scale to the charge increased the density of the steel, particularly in the case of ores low in iron contents. The density of the sintered product obtained varied from 4 to 7. The compact could be hot worked by forging or swaging, with increase in density. The resultant material was amenable to heat treatment. It is believed that the process has useful potential applications on the cottage industry scale in this country for the production of small agricultural and other tools in rural areas where iron ore is available. The process involves very low capital outlay and operating labour charges.