| 摘要 |
Gas from roasting containing SO2, As cpds. and opt. Sb and Pb cpds. is purified by direct cooling, condensation and absorption with circulating H2SO4 in which As2O3 is kept in suspension in excess of saturation content, so that As2O3 condensed and absorber from gas is precipitated on suspended As2O3 particles. Circulating acid is kept at 50-90, pref. 55-80 degrees C by adding water in an amt. corresponding to that removed as vapour with directly cooled and purified gas. In this way, purification is carried out under such conditions that incrustation and corrosion problems are avoided. H2SO4 concentration should be 1-50, pref. 3-35, esp. 5-30 wt. % and gas temp. 180-435 degrees C.
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