硫酸铵浸出离子型稀土矿对土壤和地下水污染的研究现状

我国的离子型稀土矿多采用硫酸铵原地浸出工艺富集,该工艺对土壤和地下水均会造成污染。根据硫酸铵原地浸出稀土矿的机理和工艺现状,分析了在浸出过程中对土壤和地下水环境所造成的氨氮污染、重金属污染、稀土元素污染及酸化等。总结了浸矿中所产生的NH_4~+、SO_4~(2-)、H~+、重金属离子、稀土离子等污染物在土壤和地下水中的迁移及转化路径。各污染物随浸出液通过渗透作用进入土壤和地下水,在此过程中,部分NH_4~+被氧化为NO_2~-、NO_3~-,SO_4~(2-)被还原为S~(2-)以及与Ca~(2+)反应生成CaSO_4。

Current status of research on soil and groundwater contamination by ammonium sulfate leaching of ionic rare earth ores

Most of the ionic rare earth ores in China are enriched by ammonium sulfate in-situ leaching process, which can cause pollution to both soil and groundwater. According to the mechanism and process status of ammonium sulfate in-situ leaching of rare earth ores, the ammonia-nitrogen pollution, heavy metal pollution, rare earth element pollution and acidification caused to the soil and groundwater environment during the leaching process were analyzed. The migration and transformation paths of NH4+, SO42-, H+, heavy metal ions, rare earth ions and other pollutants produced in the leaching ore in soil and groundwater were summarized. Each pollutant enters the soil and groundwater with the leachate through percolation, and in this process some NH4+ is oxidized to NO2- and NO3-, SO42- is reduced to S2- and reacts with Ca2+ to form CaSO4.