Abstract:

The release of heavy metals in the process of storage and utilization of red mud may cause environmental pollution. In order to further explore the release characteristics of heavy metals in red mud in different environments, the contents and occurrence forms of different heavy metals in red mud were first determined, and the effects of leaching agent pH, leaching time, solid-liquid ratio, raw material particle size and leaching temperature on the leaching characteristics of red mud heavy metals were investigated. Combined with risk assessment coding method (RAC) and secondary and primary comparison value method (RSP), the environmental pollution characteristics of different occurrence of heavy metals in red mud were evaluated. The results showed that the content of As, Cr, Cu, Mn, Ni and Pb in red mud was high, and the occurrence form of heavy metal elements was mainly residue state. The pH of the extraction agent had great influence on the leaching of Pb, Cr, Ni, Cu and Mn. With the increase of solid-liquid ratio and the extension of reaction time, the leaching amount of heavy metals in red mud increased. Reducing the size of red mud was beneficial to the leaching of heavy metals such as Cr. To a certain extent, the high reaction temperature will promote the leaching of heavy metals in the red mud, but when the reaction temperature exceeded 50℃, the leaching amount of heavy metals will decrease. Environmental pollution evaluation analysis showed that the biological availability of heavy metals in red mud was small, and it was not easy to be absorbed by organisms, but the heavy metals Cr and Cu in red mud had a greater risk of migration and transformation in the environment, and attention should be paid to strengthening the solidification of Cr and Cu during the storage and utilization of red mud.

Key words: red mud, heavy metals, leaching characteristics, occurrence form, environmental pollution

摘要：

赤泥在堆存和利用过程中重金属的释放可能会对环境造成污染。为了深入探究赤泥中重金属在不同环境中的释放特性，本文首先测定了赤泥中不同重金属的含量及其赋存形态，考察了浸提剂pH、浸出时间、固液比、原料粒径及浸出温度对赤泥重金属浸出特性的影响，并结合风险评价编码法（RAC）以及次生相和原生相比值法（RSP）评价了赤泥中不同赋存重金属对环境的污染特性。结果表明，赤泥中As、Cr、Cu、Mn、Ni、Pb含量较高，重金属元素的赋存形态主要为残渣态。浸提剂pH对重金属Pb、Cr、Ni、Cu和Mn等的浸出影响较大；随着固液比增大和反应时间延长，赤泥中重金属浸出量增大。减小赤泥粒径有利于Cr等重金属的浸出。一定程度上升高反应温度将促进赤泥中重金属的浸出，但当反应温度超过50℃时，反而会使重金属浸出量下降。环境污染性评价分析表明，赤泥中各重金属的生物有效性较小，不容易被生物体吸收，但是赤泥中重金属Cr和Cu在环境中的迁移转化风险较大，在赤泥堆存和利用过程中，要注意加强对Cr和Cu的固化。

关键词: 赤泥, 重金属, 浸出特性, 赋存形态, 环境污染性