Abstract: The offgas discharged during the preparation of acids from pyrite by contacting method contains generally 0.2%~0.5% (volume fraction,same below) SO₂ and 0.004%~0.008% acid mist.At present,‘one conversion and one absorption’ process or ‘two conversions and two absorptions’ process are commonly used in China to absorb sulphuric acid tail gas such that the SO₂ content thereof is as low as about 0.01%~0.1%.With the increase of sulphuric acid producti-vityor the capacity expansion of enterprises,however,the total emission of SO₂ still overpasses significantly the requirement of Environmental Protection Department.Technical improvement on treating sulphuric acid tail gas by three-stage amine absorption process was summarized,based on the practice carried out in the sulphuric acid workshop of Zhongdong Chemical Engineering Limited Corporation of Wuhan.

Key words:  , sulphuric acid, tail gas, three-stage amine absorption process, ammonium sulphite