Property Distinguish of Gypsum Residues of Low-concentration SO₂ Flue Gas Purification Desulfurization of Typical Tin Smelting and Countermeasures on Environmental Management in Yunnan

Low-concentration SO₂ flue gas purification desulfurization residues of typical tin smelting processing contains toxic and harmful elements such as heavy metals.Due to the unknown solid waste properties,the desulfurization residues may cause unseen environmental risks when they were stored,transferred and disposed.Extraction toxicity and corrosively identification experiment of solid waste had been used to identify 31 samples of the desulfurization residues in Yunnan Province.The results showed that 93.5% of As content and 100% of Hg content in the extraction solution exceed the limits of toxicity identification standard and the pH value of three samples are greater than 12.5,which meant the desulfurization residues were toxic and corrosive.Therefore,the samples of typical desulfurization residues which generated from low-concentration SO₂ flue gas purification of tin smelting were hazardous waste.Countermeasures were put forward.