Cost-Effective Quality Refractories for Ferro-Alloy Smelting Furnaces

Abstract

Ferro-alloy smelting furnaces are electrothermic in nature where various alloys are produced. Lining of these furnaces with cost-effective quality refractories is an important factor for attaining longer campaigns, better productivity and lower cost as well. Selection of refractories for the lining of these furnaces is based on the methodology of smelting practice, the characteristics of slag and alloy compositions. The development of these refractories for lining of ferro-alloy smelting furnaces has been rather very sluggish as compared to blast furnaces and steel making vessels. Most of the ferro-alloy smelting furnaces use conventional refractory lining used about three to four decades ago. The main reason with respect to this is that furnace loads were relatively low as compared to the dimensions of the furnace. At present, the need for increased furnace availability has forced the refractory manufacturers to develop cost-effective quality refractories. In this paper, an attempt has been made to highlight the R&D work carried out at NML regarding high alumina refractories and carbon bricks from indigenous raw materials. Super duty fire clay bricks or high alumina and alusite bricks are presently used in the side lining which is prone to alkali attack and carbon monoxide disintegration . The hearth bottom, hearth walls are invariably lined with carbon bricks and blocks, due to their properties suiting the operation of the furnace. The refracton,sub-hearth which is below the bottom hearth and plays a very important role in the campaign life of the furnace is lined with 80-90% alumina bricks. Refractories for lining tap hole, runner and plug for smooth production offerro alloys have also been described in this paper.