Use of spent Potlining from the Aluminium Electrolytic cell as an additive to Arc Furnace Steel Melting and Cupola iron Melting in Steel industries

Abstract

Use of arc furnace steel melting is increasing very fast due to certain advantages offered by it. It is carried out with industrial coke (nut coke and petro coke) as an additive for composition adjustment and carbon pick up by the steel, while in cupola iron melting this coke is used mainly as fuel. Low quality coke can also be used for these purposes. The cost of production increases to a considerable extent due to use of the industrial coke. Efforts are going on to replace the same without affecting the properties of the product. Spent potlinings or SPL (waste cathode lining material from aluminium smelters) may be one of such material. It has 45- 50% of carbon in addition to other impurities as calcium oxide (CaO), iron oxide (FeO), silica (SiO2), alumina (A12O3), sodium fluoride (NaF), sodium cyanide (NaCN) etc. The toxic nature of spent potlining due to presence of cyanide and fluoride requires safe disposal. One way of disposing this is to use it in arc furnace steel melting and cupola iron melting in iron and steel industries. Western countries use this material in arc furnace steel melting for composition adjustment and as supplementary fuel in cupola iron melting, thus reduce the pollution hazards which may occur due to the storage of this material. Quality wise it resembles the low grade coke used in steel industries for different purposes. Financially it is found much cheaper as compared with conventionally used coke. There is an urgent need to assess the same material under Indian context. The requirements of the iron and steel making process and the characteristics of the SPL material are considered in this paper with a view to explore the possibility of its use in the steel industries.