Reduction of silica in coke with ash of increased basicity

Abstract

It is known that much of the silicon found in the hot metal originates from the ash of the coke which is rich in silica. The silica of the ash is reduced to volatile silicon monoxide corresponding to reactions SiO/sub 2/ + C = SiO + CO and 2 SiO/sub 2/ + SiC = 3 SiO + CO and the SiO is then transferred via the gas phase to the iron droplets descending in the furnace. At the tuyere level the iron phase may have silicon contents of several percents. Much of this silicon is oxidized again to silica by the slag in the hearth, but these reactions are sluggish and do not reach equilibrium. That is, the silicon content of the hot metal is higher than that at equilibrium with the slag, and depends considerably on the extent of the reactions of the coke ash.