膜法回收稀土冶金过程中废酸的可行性研究

Feasibility Study of the Waste Acids Recovery by Membrane Techniques in Rare Earth Metallurgy

对用减压膜蒸馏法及扩散渗析法回收稀土冶金过程中的废酸(盐酸及硫酸)的可行性进行了研究.结果表明,减压膜蒸馏能回收稀土氯化物溶液中高达80%的游离盐酸,且由于对稀土离子的截留率一般大于98%,在减压侧能回收得到较纯的盐酸溶液;扩散渗析法也能有效回收硫酸稀土溶液中的硫酸,在实际操作时控制硫酸回收率为70%～80%,水料流量比在1左右较为合适:采用减压膜蒸馏与扩散渗析的集成膜法回收硫酸稀土溶液中的硫酸,对稀土离子的截留率基本无影响,但增大了回收液的硫酸浓度,大大减少了扩散渗析的处理量,而浓缩倍数越大效果越明显.

Feasibility study was done on recovering waste acid(Hydrochloric and sulfuric acid) by vacuum membrane distillation and diffusion dialysis in rare earth metallurgy.Results show that up to 80% of free hydrochloric acid can be recovered from rare earth(RE) chloride solutions by vacuum membrane distillation(VMD).Furthermore,more pure hydrochloric solution can be recovered in the permeate side,due to cut-off rate for rare earth ion usually above 98%.Sulfuric acid also can be recovered from RE sulphate solutions by diffusion dialysis(DD).The recovery rate of sulfuric acid can be controlled between 70%～80% in the actual practice, while the ratio of water to feed in the flow is approximate at 1.The experimental results showed that sulfuric acid recovered from RE sulphate solutions by the combination of VMD and DD has no influence on the cut-off rate of RE ion,but increased the concentration of recovered sulfuric acid,and greatly decreased amount to be treated by DD.