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为了实现稀土生产草沉废水的资源回用,对稀土草酸沉淀废水建立资源回收工艺,回收废水中的草酸和盐酸。研究包括草沉废水水质分析、草沉废水蒸馏分离工艺研究、蒸馏盐酸的回收利用、盐酸蒸发过程中的浓度变化趋势分析、草沉废水草酸回收研究以及工艺经济性分析。结果表明:草沉母液中TOC含量为4 661 mg/L,金属离子总体含量不高;通过常压实沸点蒸馏发现,草沉母液可回收5 mol/L盐酸330 m L/L或1 mol/L盐酸600 m L;蒸发后草酸产率超过16 g/L草沉废水;并且结晶草酸纯度≥99.5%,硫酸根未检出,灼烧残渣≤0.16%,重金属(以Pb计)≤0.000 01%,铁离子≤0.0045%,氯化物≤0.08%。通过上述研究,为草沉废水资源化处理技术的工业化应用提供了理论依据。
In order to realize the reuse of resources of rare earth grass straw wastewater, a resource recovery process was established for the rare earth oxalate precipitation wastewater to recover the oxalic acid and hydrochloric acid in the wastewater. The research includes the analysis of the quality of grass sediment wastewater, the research of distillation and separation technology of grass sediment wastewater, the recovery and utilization of distilled hydrochloric acid, the analysis of the change trend of concentration during the evaporation of hydrochloric acid, the recovery of oxalic acid from straw wastewater and the analysis of process economy. The results showed that the content of TOC was 4 661 mg / L and the total content of metal ions was not high. The concentration of metal ions was found to be 330 mol L / L or 1 mol / L hydrochloric acid 600 m L; the yield of oxalic acid after evaporation is over 16 g / L grass sediment wastewater; the purity of the crystalline oxalic acid is over 99.5%; the sulfate is not detected; the residue on ignition is less than 0.16%; the content of heavy metals on Pb is less than or equal to 0.0001 %, Iron ion ≤0.0045%, chloride≤0.08%. Through the above research, it provides a theoretical basis for the industrialized application of the grass-roots wastewater treatment technology.