Exploitation of banded hematite quartzite and Jhama coal for the production of higher grade ferro-silicon

Abstract

Ferro-alloy industries are backbones of steel industries because of its wider application such as an alloying element and in some cases as deoxidizer. In the Pidgeon process for production of magnesium from dolomite ferrosilicon is used. Ferrosilicon is used as inoculants which accelerate graphitization during the production of cast iron. In arc welding, ferrosilicon is used in electrode coatings. Recently, Indian ferro-alloys industries are passing through one of its worst periods by the process of economic liberalization. With the recent reductions in custom duties, the exports are becoming cheaper. It has been hit hard rather than being helped in its growth through additional investment. Thus the production of ferro-alloys in our country is coming down mainly due to inadequate industries demand, non-availability of exports, high power cost and non-availability of low ash coking coal. In view of the above challenges, the present investigation has been taken up with a process development for the production of ferrosilicon using lean grade Banded Hematite quartzite (BHQ) and unutilized low reactive coals such as Jhama coal as a reducing agent. In the present study, ferrosilicon has been successfully produced at a pilot scale of 500 kVA Submerged Arc Furnace and process parameters were optimized for the production of graded ferrosilicon using different combinations of (i) BHQ, and Jhama coal (ii) BHQ, quartzite and Jhama coal (iii) BHQ, quartzite, Jhama coal with petroleum coke and (iv) BHQ, quartzite and petroleum coke. A maximum grade of 65% Fe-Si could be economically produced with these combinations. The present invention is particularly relates to a process for smelting reduction of Banded Hematite Quartzite (BHQ) in a submerged arc using low reactive Jhama Coal for producing ferrosilicon. The invention is useful to recover values from low grade materials such as Banded Hematite Quartzite (BHQ) and low reactive coal, which are not being currently used for any of the production processes in iron and steel sector or alloy steelmaking, and therefore important from the view point of environmental protection and waste resource utilization. In other words the present investigation focused on the production of high grade ferrosilicon using easily and cheaply available raw materials to minimize the production cost.