利用含重金属土壤制备烧结砖可行性及环境安全性研究

为探明利用含重金属土壤作为页岩替代原料制备烧结砖的可行性和环境安全性，选取某砖窑以70%的比例掺加该土壤替代页岩开展工业化试验，研究重金属在烟气中的排放情况及在成品砖中的浸出率和分配规律。结果显示：土壤中SiO₂、Al₂O₃和Fe₂O₃浓度与页岩原料相似，可以用作页岩原料的替代；烧制的成品砖力学性能符合产品质量标准。在以含重金属土壤为原料的砖块烧结过程中，烟气中常规污染物和重金属污染物排放均满足相关标准，环境风险可控；烧结砖中可浸出重金属浓度显著低于GB 30760—2014《水泥窑协同处置固体废物技术规范》浸出限值，砖块在使用过程中的重金属浸出风险较低；As、Cd、Cr、Mn、Ni、Pb和Cu在烧结过程中基本赋存在成品砖里，经烟气挥发和湿法脱硫压滤后留存于脱硫滤饼中的重金属含量极低。研究表明，利用含重金属土壤制备烧结砖从产品力学性能及环境安全性上均能满足现有标准，具有一定的资源化利用效益。

Feasibility and environmental safety investigation of making fired bricks by using heavy metals-contained soil

Soil heavy metal pollution in China is still relatively serious, and inappropriate disposal of heavy metal contaminated soil can lead to a serious damage to both the ecological environment and human health. However, soil normally contains a significant amount of SiO2, Al2O3 and Fe2O3, which makes it applicable to prepare sintered bricks. In order to ascertain the feasibility and environmental safety of making sintered bricks by using heavy metal contained soil, an industrialization experiment was carried out in a brick kiln, with a blending ratio of 70% soil to replace shale, to investigate the heavy metal emission in flue gas, and the leaching and distribution properties in fired brick. The results revealed that soil had a similar content of SiO2, Al2O3 and Fe2O3 compared to shale, and therefore, it could be used as a substitute for shale raw materials. The mechanical properties of the fired bricks met the product quality standards. During the sintering process with heavy metal soil as raw material, the emission of conventional flue gas pollutants and heavy metal pollutants met the relevant standards, and the environmental risk was controllable. The concentration of leachable heavy metals in sintered bricks was significantly lower than the leaching limit of Technical Specification for Cooperative Disposal of Solid Waste in Cement Kilns （GB 30760-2014 ）, and therefore, the leaching risk was low during using bricks. As, Cd, Cr, Mn, Ni, Pb and Cu basically stayed in fired bricks under sintering, and the contents of heavy metals remained in the desulfurization filter cake after flue gas volatilization and wet desulfurization filter pressing were extremely low. The research showed that using heavy metal-contained soil to make sintered brick could meet the existing standards from both mechanical and environmental safety aspects and had certain resource benefits.