离子型稀土矿开采过程中氨氮吸附解吸行为研究

发布时间：2018-03-06 09:28

本文选题：离子型稀土　切入点：地下水污染　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：稀土可广泛用于军事、冶金、石油化工等各个方面,是具有重要战略意义的产品。我国南方离子型稀土矿现行开采工艺为原地浸矿开采法,生产中采用高浓度硫酸铵做浸矿剂使土壤吸附大量的铵态氮,因此开采过程中氨氮对环境造成的污染十分严重。为解决氨氮污染,需先了解氨氮的吸附机理及其在土壤中的赋存情况,在此基础上采取淋洗手段解吸土壤的铵态氮。论文采取室内实验方法,根据实际工况对采集到的原矿进行了土样对氨氮的吸附实验,研究了开采工况下氨氮吸附的机理,并对吸附饱和的土样进行了解吸附实验,确定了不同形态铵态氮所占的比例及含量。另外研究了不同淋洗方案的可行性,并通过柱实验对实际工况进行了模拟,应用Cl-浓度为250mg/l的KCl溶液淋洗方案,研究了实际可行性。主要的结论如下:1)动力学结果同颗粒内扩散模型和Elovich方程拟合均较好。土体对氨氮的吸附平衡时间为3小时,在开采工况下土体对氨氮的饱和吸附量约为770mg/kg。通过Langmuir Freundlich方程的参数得到土体对氨氮的理论最大饱和吸附量为970mg/kg。2)批实验中吸附饱和的土体所含的铵态氮中,能被去离子水解吸的部分约占总铵态氮的33%,1M的KCl溶液可解吸的部分占总铵态氮的60%,剩余存在矿物晶格中的部分约占6%。3)现行清水淋洗措施效率低且无法解吸交换态铵态氮,而Cl-浓度为250mg/l的KCl溶液可快速且有效地浸提土中残存铵态氮,适宜应用在实际生产中。4)模拟实际的柱实验中吸附平衡的土体中水溶态铵态氮比例上升至53%,交换态铵态氮所占比例降至47%,不存在固定态铵态氮或存在量极小。
[Abstract]:Rare earths can be widely used in military, metallurgical, petrochemical and other fields. High concentration ammonium sulfate is used as leaching agent to absorb a large amount of ammonium nitrogen in the soil in production, so the pollution caused by ammonia nitrogen during mining is very serious. In order to solve the pollution of ammonia nitrogen, It is necessary to understand the adsorption mechanism of ammonia nitrogen and its occurrence in soil, on the basis of which the leaching method is adopted to desorb the ammonium nitrogen in soil. According to the actual working conditions, the adsorption experiments of ammonia nitrogen were carried out on the soil samples, the mechanism of ammonia nitrogen adsorption under mining conditions was studied, and the adsorption experiments were carried out on the saturated soil samples. The proportion and content of different forms of ammonium nitrogen were determined. In addition, the feasibility of different elution schemes was studied, and the actual conditions were simulated by column experiments. The leaching scheme of KCl solution with Cl-concentration of 250 mg / l was used. The practical feasibility has been studied. The main conclusions are as follows: (1) the kinetic results fit well with the particle diffusion model and the Elovich equation. The adsorption equilibrium time of the soil for ammonia nitrogen is 3 hours. Under mining condition, the saturated adsorption capacity of ammonia nitrogen is about 770 mg / kg. The theoretical maximum saturated adsorption capacity of soil for ammonia nitrogen is 970 mg / kg 路2 through the parameters of Langmuir Freundlich equation. The part that can be desorbed by deionized water accounts for about 331M of total ammonium nitrogen. The desorbed part of KCl solution accounts for 60% of total ammonium nitrogen, and the remaining portion of mineral lattice is about 60.3.The current clean water elution measures are inefficient and cannot desorb exchangeable ammonium nitrogen. The KCl solution with a concentration of 250 mg / l can rapidly and effectively extract residual ammonium nitrogen from the soil. It is suitable for application in practical production .4) in the actual column experiment, the proportion of water-soluble ammonium nitrogen in the soil adsorbed in equilibrium rises to 53 and the proportion of exchangeable ammonium nitrogen decreases to 47, and there is no fixed ammonium nitrogen or minimal amount of ammonium nitrogen in the soil.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X753

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