回转窑共处置砷的实验研究

CO-PROCESSING OF ARSENIC BY CEMENT ROTARY KILN

砷(As)是一种有毒致癌物质,也是致癌、致突变元素。实验将有机砷(C6H8AsNO3)添加到水泥生料中,模拟回转窑协同处理含砷污泥的过程。主要研究不同砷掺加量(0%、2%、5%、7%和10%),不同煅烧温度(1 250,1 350,1 450℃)对水泥熟料游离氧化钙(f-CaO)和砷浸出性的影响。采用扫描电子显微镜(SEM)和X-射线衍射仪(XRD)对样品的表面形貌和物相进行测试。同时对砷的固化率进行测试。实验结果表明:掺加C6H8AsNO3对水泥f-CaO影响明显,能有效降低烧成温度50~100℃。掺烧量的大幅度提高(2%~10%),对f-CaO影响不大。毒性浸出实验结果表明当烧成温度为1 450℃时,浸出结果远远低于GB 5085.3—2007允许的浸出值。SEM和XRD分析测试表明砷掺量2%对水泥矿物形貌和矿物相影响不大,砷的固化率为80.29%。

Arsenic( As) is a toxic and carcinogenic substances. The organic arsenic( C6H8AsNO3) was added to the raw material in cement rotary kiln to simulate the coordination process of sludge containing arsenic. The effects of the different arsenic content( 0%,2%,5%,7% and 10%) and the calcination temperature( 1 250 ℃,1 350 ℃ and 1 450 ℃) on free calcium oxide( f-CaO) and the leaching of arsenic were investigated. The sample surface morphology and phase were tested by Scanning Electron Microscopy( SEM) and X-ray Diffraction( XRD). Besides,the curing rate of arsenic was measured. The results showed that the addition of C6H8AsNO3 can effectively decrease the sintering temperature by 50 ~ 100 ℃. When the amount of C6H8AsNO3 varied from 2% ~ 10%,the values of f-CaO were little affected. When sintering temperature was1 450 ℃,leaching results were far below the limit of GB 5085. 3—2007. SEM and XRD analysis indicated that arsenic content of 2% had little influence on the morphology of cement,and the curing rate of arsenic was 80. 29% at 1 450 ℃.