支撑液膜技术从碱性氰化液中分离Au(I)及其机理研究

Extraction of gold(I) from alkaline cyanide solution has become a hot topic in hydrometallurgy. However, the industrial application of Au(I) solvent extraction hasn't been performed so far mainly for two reasons: Firstly, the gold concentration in industrial heap leaching liquor is very low, only about 1 mg/L to 20 mg/L, which makes the solvent extraction process must be carried out at a high aqueous/organic phase ratio.Thus much organic solvent loss is unavoidable. Secondly, it is hard to strip gold from the loaded organic phase. In this program, we will combine the solvent extraction technology and membrane separation technology, to isolate Au(I) from alkaline cyanide solution using the technology of supported liquid membrane (SLM). SLM system in comparison to solvent extraction technology offers numerous advantages such as combine extraction and stripping into one single stage, high separation efficiency, excellent selectivity, low capital investment and operating cost, simple to operate and easy to scale up, which can overcome the extraction shortcoming of using a large amount of solvent,readily emulsion and organic phase loss.Optimal condition to separate Au(I) from alkaline cyanide solution will be selected in this program, which includes the selection of extractants, membrane materials and configuration of SLM system.The mechanism of this procedure will be be reviewed to enrich and develop the mechanism of extraction of gold. Beside its original value, the project has a significant theoretical meaning and significant practical value.

从碱性氰化液中萃取金是湿法冶金中的热点课题，但因矿石氰化液中金的浓度很低，即使采用适应W/O大相比的萃取设备，有机溶剂消耗仍然很大，且载金的有机相极难反萃，至今未见实践报道。本项目将溶剂萃取技术与膜分离技术相结合，开展支撑液膜(SLM)从碱性氰化液中分离Au(I)的研究。支撑液膜分离技术将萃取与反萃取过程合并为一步进行，能够克服液-液萃取过程中使用大量溶剂，易乳化，有机相损失大的缺点，并具有分离效率高、选择性好等优点。项目实施过程中将对支撑液膜（SLM）中使用的萃取剂载体、膜材料进行筛选，对支撑液膜分离金的工艺条件进行优化，研究出一种具有较好应用前景的新型工艺，并对支撑液膜从氰化液分离金的机理进行系统研究，提出金在支撑液膜中传递的数学模型，丰富和发展萃金理论。

本项目将溶剂萃取技术与膜分离技术相结合，开展了支撑液膜(SLM)从碱性氰化液中分离Au(I)的研究。（1）构建了一种新型高效的萃金协萃体系，突破了溶剂萃取技术在碱性条件下分离金的技术难题。成功合成了一系列新型亚砜类萃取剂，研究了胺/亚砜协萃体系对金(I)的萃取性能，优化出伯胺N1923/BESO为金(I)的最佳协萃体系。对影响金(I)萃取效率的各种因素进行了考察，优化出金(I)的最佳萃取工艺条件。对协萃体系萃取金的机理进行了详细研究，给出了N1923/BESO萃取金的萃合物模型。（2）在溶剂萃取金的基础上，以胺类/亚砜协萃剂为载体，PVDF膜为支撑材料，详细研究了支撑液膜对金(I)的分离性能。研究了萃取剂与膜材料的匹配，筛选出最佳的膜材料和萃取剂浓度，优化出最佳的支撑液膜分离金(I)的工艺条件。在最佳工艺条件下，对浓度为5.0 mg/L的氰化金溶液，可达到一次迁移率大于99%，传质系数P达到31.45×10-6 m/s。经过支撑液膜分离后，待萃室中金浓度小于0.1 mg/L，达到任务书要求的工艺指标。同时，研究了Au(I)在SLM中传输的机理，提出Au(I)在支撑液膜中传递的数学模型。（3）成功合成了基于离子液体的聚合物嵌合膜（PIM），研究了其对碱性氰化液中金的分离性能，结果表明PIM对金亦具有良好的分离性能，传质系数P可达到10.4×10-6 m/s。PIM具有比SLM更高的稳定性。综上所述，将溶剂萃取技术与膜分离技术相结合的SLM膜可将萃取与反萃取过程合并为一步进行，能够克服液-液萃取过程中使用大量溶剂，易乳化，有机相损失大的缺点，并具有分离效率高、选择性好等优点，具有良好的应用前景。