摘要：

采用钙矾石(AFt)化学沉淀法去除镁剂烟气脱硫废水中的SO₄^2-,探讨了废水浓度、pH、Al³⁺用量、搅拌速度、反应时间等因素对SO₄^2-去除率及Ca²⁺、Al³⁺残留量的影响。结果表明, 对经预处理后SO₄^2-质量浓度为2 086 mg/L的镁剂脱硫废水, 当pH=11,n(Al³⁺):n(SO₄^2-)=0.575,搅拌转速为300 r/min,反应时间为10 min时, SO₄^2-去除率可达到92.1%,Ca²⁺、Al³⁺残留质量浓度分别为187、4 mg/L.SEM/EDS测试结果表明, 沉淀产物为针状纳米钙矾石结晶, 其在混凝土膨胀剂和阻燃领域具有良好的应用前景。

关键词: 钙矾石, 硫酸盐废水, 化学沉淀

Abstract:

Ettringite(AFt) chemical precipitation process has been used for removing SO₄^2- from magnesium flue gas desulfurization(MFGD) wastewater. The effects of the factors, such as wastewater concentration, pH, Al³⁺ dosage, stirring speed, reaction time, etc. on the removing rate of SO₄^2- and the residual amount of Ca²⁺ and Al³⁺ are discussed. The results show that for the pretreated magnesium flue gas desulfurization wastewater whose mass concentration of SO₄^2- is 2 086 mg/L, under the following conditions:pH=11, n(Al³⁺):n(SO₄^2-)=0.575, stirring speed 300 r/min, and reaction time 10 min, the SO₄^2- removing rate can reach 92.1%, and the residual mass concentration of Ca²⁺ and Al³⁺ are 187 mg/L and 4 mg/L, respectively. SEM/EDS result shows that the precipitated product is a kind of needle-like nano ettringite crystal. It has pretty good application prospects in the fields of concrete swelling agent and flaming retarding.

Key words: ettringite, sulfate wastewater, chemical precipitation

中图分类号: 

• X703.1