FE314 Finnish expert report on best available techniques in ferrochromium production
Marja Riekkola-Vanhanen, 1999.
The Finnish Environment 314, p. 49. URN:ISBN 9521105046. The publication is available also in printed form (ISBN 952-11-0504-6).
Abstract
The aim of this BAT report is to identify available techniques for the reduction of emissions and energy use in the primary ferrochromium production in Finland. The process used consists of a steel belt sintering plant and two preheating and smelting furnaces. In the sintering plant, chromite concentrate is pelletised. The thermal energy is obtained by combustion of coke dust added to the pellets, while carbon monoxide produced by the smelting process is employed as an additional fuel. The smelting charge is preheated, which saves electricity and increases the capacity of the smelting furnaces by 20 %. A considerable part of the molten ferrochromium is transferred to the adjacent steel melting shop.
The total dust emissions to air are 80-120 g/tonne of ferrochromium. They come from coke drying, sintering, dosing, preheating, slag granulation and product handling processes. Correspondingly, the CO emissions are 500-700 kg/t FeCr without the use of CO-gas in stainless steel production, the NO2 emissions are 0.8-1.2 kg/t FeCr and those of SO2, 0.3-0.5 kg/t FeCr.
The energy provided by the carbon monoxide corresponds to 45,000-50,000 tonnes of oil a year, which results in considerable savings. Combustion of the sulphur free carbon monoxide is also important from the point of view of environmental protection.
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