GB775818A - A process for removing dust from gases - Google Patents

Abstract

Dust, particularly iron oxide dust, is removed from hot gases by contacting the dust-laden gases with hot slags or slag-forming materials which are capable of chemically incorporating the dust material to form relatively low-melting slags. Suitable slag-forming materials which may be used are silica, silicates, calcium oxide, alumina or aluminium compounds, calcium fluoride, phosphorous compounds, e.g. P2O5, boric acid and its compounds, and alkali compounds, e.g. sodium silicate or sodium carbonate, either alone or in the form of a combination of two or more components giving highly fluid slags. The fluidity of the slag may be increased or the melting temperature may be lowered by adding materials such as fluorspar, bauxite, low-fusing clays, fireclay, sodium carbonate, boric acid, or potassium or sodium glasses, alone or in a mixture containing several components. Slag-forming substances and/or fluxes may be periodically or continuously fed to the melt. If heat is required, other than that provided by the sensible heat of the hot gases, it may be provided by burning part or all of the CO contained in the gases. A suitable slag formed from quartz sand and lime with an addition of iron oxide contained e.g. 31 per cent SiO2, 49 per cent FeO and 20 per cent CaO and had a melting temperature of 1205 DEG C.