Glycine has been intensively investigated as a “green” lixiviant for precious and base metals. Alkaline glycine solutions to extract Ni from sulfide resources has shown promising results. However, a considerable amount of Ni will be lost in the wash solutions when leaching residues are washed during solid-liquid separation of the leachates from their respective leach residues. In this context, this study explored Ni recovery from alkaline glycine-based wash solutions using a polyamide nanofiltration membrane. In the tests using synthetic single and multi-metal solutions, the membrane achieved >95% rejection of Ni in the selected ranges of glycine/Ni molar ratio (up to 5), pressure (15–30 bar), initial nickel concentration (0.5–1.5 g/L), sodium sulfate background concentration (∼30 g/L) and under the use of different pH modifiers (aqueous ammonia and caustic soda). When using a real solution, the concentrations of Ni and other major elements (Cu, S, Co, Mg, Zn) in the final retentate increased by about 5 times at 80 wt% permeate recovery, leaving <3 mg/L major elements in permeate. The permeate stream could be recycled in the washing stage, and the retentate stream could be combined with the pregnant leach solution (PLS) for metals recovery. The investigation demonstrates some of the technical optionality for nickel recovery from filter wash solutions utilising nanofiltration within the context of alkaline glycine-based leach technology and preliminarily demonstrates where it can be used in the structure of flowsheets to recover valuable base metals and reagents for recycle. However, the increased membrane resistance causing a low permeate flux should be concerned due to the considerable dissolved salts, precipitation of gypsum and the increasing feed concentration over time.

中文翻译：

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应用纳滤从聚酰胺膜从碱性甘氨酸溶液中回收甘氨酸镍：技术说明


甘氨酸作为贵金属和贱金属的“绿色”浸滤剂已被深入研究。从硫化物资源中提取镍的碱性甘氨酸溶液已显示出有希望的结果。然而，在将浸出液与其各自的浸出残渣进行固液分离的过程中，对浸出残渣进行洗涤时，大量的镍会损失在洗液中。在此背景下，本研究探索使用聚酰胺纳滤膜从碱性甘氨酸洗涤溶液中回收镍。在使用合成单金属和多金属溶液的测试中，在选定的甘氨酸/镍摩尔比（高达 5）、压力（15–30 bar）、初始镍浓度（0.5 –1.5 g/L)、硫酸钠背景浓度 (∼30 g/L) 并使用不同的 pH 调节剂（氨水和烧碱）。当使用真实溶液时，最终渗余物中 Ni 和其他主要元素（Cu、S、Co、Mg、Zn）的浓度在 80 wt% 渗透液回收率下增加了约 5 倍，留下 <3 mg/L 主要元素渗透。渗透物流可以在洗涤阶段循环利用，渗余物流可以与富浸出液（PLS）合并以回收金属。该研究展示了在碱性甘氨酸浸出技术背景下利用纳滤从过滤器清洗溶液中回收镍的一些技术可选性，并初步证明了它可以在流程结构中用于回收有价值的贱金属和试剂以进行回收。 然而，由于大量的溶解盐、石膏沉淀以及进料浓度随时间的增加，膜阻力增加导致渗透通量低，应引起关注。