To address the technical bottleneck of deep removal of key impurities such as Cu, Pb, As and Bi in the hydrometallurgical extraction of antimony, a process for producing low-impurity cathode antimony by diaphragm electrowinning in alkaline system was investigated. The effects of single-factor conditions, including current density, electrolysis temperature, electrolyte circulation rate, and electrode spacing, on the purity of cathode antimony and typical impurity content, surface morphology of the cathode deposit, cell voltage, current efficiency, and DC power consumption during the diaphragm electrowinning process in Na2S-NaOH alkaline system were systematically analyzed. The results show that pre-electrolysis can significantly reduce and effectively control metal impurities with electrode potentials close to or more positive than that of antimony in the electrolyte. The appropriate pre-electrolysis pretreatment technology combined with the optimal alkaline diaphragm electrowinning process can achieve effective control of difficult-to-remove impurities such as Cu, Pb, As, and Bi in cathode antimony. Under the optimal process conditions, a dense, bright cathode antimony with excellent morphology and a purity of 98.61% can be obtained, with an average cell voltage of 2.3 V, a cathode current efficiency of 90.93%, and a DC power consumption of 1 667.2 kWh/t. The impurity As content meets the single impurity content requirement of 5N-grade high-purity antimony Sb-05 specified in the national standard "High Purity Antimony" (GB/T 10117—2021), and the removal rates of Cu, Pb, and Bi reach 66.41%, 99.62%, and 98.56%, respectively, which can provide stable raw materials for the subsequent low-cost preparation of high-purity antimony.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |