铬污染土壤制砖的工艺研究

Process Study on Soils Contaminated by Chromium for Brick Making

开展了铬污染土壤与无烟煤混合后烧结制砖的研究,着重探讨了温度对浸出液中总铬和六价铬含量的影响。铬污染土壤与煤粉、水混合均匀后,通过挤压、切条、切坯、干燥等工艺处理后,进入窑内进行烧结。试验过程中每隔3 h,在不同位置测定窑温。保温时间为3 h决定性的作用,当温度大于1000℃时,98%以上的六价铬在还原气氛下已转化为三价铬或被固定在砖体中。而当温度低于900℃时,样品全部不合格。建议在土壤修复施工过程中,严格控制窑温在1000℃以上。

This paper studied on brick making using chromium contaminated soils and anthracite.Hexavalent chromium and total chromium in leaching solution were evaluated under different sintering temperature.Chromium contaminated soil mixed with pulverized coal and water evenly,then treatment by extrusion,slicing,billet cutting and drying procedures,finally sintered in kiln.Kiln temperature was measured at different locations every 3 h during the test.Insulation time was 3 h.The leaching toxicity of brick products was detected by batch sampling after they were out of kiln.It is concluded that the toxicity removal effectiveness was depended on strongly the temperature.More than 98%hexavalent chromium were converted to trivalent chromium or be fixed in the brick demonstrates under the reducing atmosphere at the temperature higher than 1000℃.When the temperature was below 900℃,all the samples were not qualified.We suggested that the kiln temperature should be strictly controlled above 1000℃in soil rehabilitation project.