水泥窑共处置含Cr废物中Cr在不同温度下的形态转化

Form Transformation of Cr during Co-Processing Waste Contained Cr in Cement Kiln at Different Temperatures

将Na2CrO4加入生料中模拟含Cr入窑物料[掺加比例为0．048％（以W计）]，以探索水泥窑共处置含Cr废物过程中Cr的形态转化．将含Cr入窑物料在不同温度条件下进行煅烧，消解煅烧样品以分析Cr在不同温度下的残留率并利用XANES（X射线吸收近边结构光谱）技术分析煅烧样品中Cr的存在形态．结果表明：对应900、1000、1100、1200、1300和1450℃煅烧条件下，熟料中Cr的残留率分别为88．2％、70．7％、73．7％、67．2％、69．5％和67．8％．由于窑尾温度为1050—1100℃，并且Cr的残留率在1100℃较高，因此从窑尾添加含Cr废物可以减少水泥窑共处置含Cr废物过程中的Cr逸放．在900～1450℃煅烧条件下，所有样品中的Cr主要以CrO3、Cr2O3和CaCrO4的形式存在．1000℃煅烧温度下存在K2Cr2O7，但不存在K7CrO4；900℃和1100～1300℃煅烧温度下有K2CrO4存在，但不存在K2Cr2O7．1100～1450℃煅烧温度下，Cr元素进入到水泥熟料的主要矿物中，并主要以CrO3和Cr2O3的形式与其他物质结合生成了较为复杂的Ca4A16O12CrO4、Ca6Al4Cr2O15等．

In orde to discover the form migration of Cr during co-processing hazardous wastes contained Cr,Na2CrO4 was added to the raw material simulation Cr-containing material into the kiln （the mixing ratio is 0. 048% （w））. The raw material mixing with Na2CrO4 was calcined at different temperatures. The residual rate of Cr was studied by digestion of samples calcined. The chemical forms of Cr were obtained by X-ray absorption near edge structure （XANES）. The results showed that, the conditions of Cr clinker residual rates were 88.2% , 70.7% , 73.7% , 67.2% , 69.5% and 67.8% at temperatures of 900-1450 ℃. The kiln tail of temperature was 1050-1100 0C and was closed to 1100 ℃ , at the temperature of 1100 ℃. Therefore, it redueed the disposal of Cr during co-processing waste in the cement kiln adding waste at the kiln tail. Cr mainly existed in the forms of CrO3 , Cr203 and CaCrO4 under the conditions of 900-1450 ℃. In addition, K2 C r207 was produced under the condition of 1000 ℃ and K2 CrQwas produced under the conditions of 900,1100,1200 and 1300 ℃. Cr entered into the main cement mineral combined with other substanees to generate more complex Cr-eontaining substances such as Ca4Al6Ol2CrO4 and this material was mainly in the form of CrO3 and Cr203under the ranges from 1100 ℃ to 1450 ℃.