贵金属熔炼烟尘综合处理富集稀贵金属研究

Enrichment of Precious and Rare Metals by Comprehensive Treatment of Precious Metals Smelting Dust

以贵金属熔炼烟尘为原料,对其化学成分、物相组成和微观形貌进行了表征,采用湿法和火法联合工艺对其进行酸性浸出除杂和焙烧脱硒富集金银等贵金属。结果表明,该烟尘主要成分为Cl、Na、Ag、Hg和Se,银的主要物相为AgCl、Ag2Se,占比分别为71.97%、24.03%,硒的主要物相为单质硒、Ag2Se和HgSe,占比分别为49.25%、21.01%和13.50%,其微观结构为0.2μm左右的颗粒状;以硫酸为浸出剂,控制浸出终酸浓度24.74 g·L-1、液固质量比4∶1、温度85℃搅拌浸出2 h,优化放大实验浸出渣率为25.72%,主要杂质Na和Cl的浸出率分别为99.92%、94.49%,浸出渣中Au、Ag品位达到2.201%、23.77%,Se、Hg品位分别为20.49%、23.67%,Au、Ag、Se、Hg全部富集在浸出渣;浸出渣以H2SO4作为强化焙烧剂,在硫酸用量为渣重1. 4倍、700℃条件下焙烧3 h,烧成率为58.07%,主要杂质Se,Hg品位分别降至0.82%、0.36%,脱出率达到97.67%、99.11%,Au、Ag品位分别为3.628%、41.02%、较烟尘富集6.6倍。贵金属熔炼烟尘经过湿法-火法联合处理后,杂质得到有效脱出、贵金属得到高度富集,为后续精炼提供了良好条件。

The chemical composition,phase composition and micro-morphology of precious metal smelting dust were characterized.A new conception for comprehensive recovering precious and rare metals from precious metals smelting dust was investigated and applied to the acid leaching dust and sulfating roasting residue of dust. The results showed that the main components of dust were Cl,Na,Ag,Hg and Se,the main phases of silver were AgCl and Ag2 Se,the percentage were 71.97% and 24.03% respectively. The main phases of selenium were selenium,Ag2 Se and HgSe,accounting for 49.25%,21.01% and 13.50%,respectively,and the microstructure of the dust was particles which size was about 0.2 μm. The leaching efficiency in various conditions was investigated using sulfuric acid as agent,the results showed that the leaching efficiency of Na and Cl were 99.92% and 94.49% respectively,with the residue rate of 25.72%,and the grades of Au,Ag,Se,Hg were 2.201%,23.77%,20.49% and 23.67%,respectively,under the conditions of sulfuric acid concentration 24.74 g·L-1,mass ratio of liquid to solid 4∶1,temperature 80 ℃ and 2 h. The results showed that it was useful to sulfating roast residue using sulfuric acid as oxidant,the optimal effect was obtained when the H2 SO4 mass was 1.4 times of reaching residue and the time was 3 h at 700 ℃,the roasting efficiency of Se and Hg were 97.67% and 99.11% respectively with the residue rate of 58.07%,and the grades of Au,Ag,Se,Hg were 3.628%,41.02%,0.82% and 0.36% respectively. The impurities of precious metals smelting dust were effectively removed after the combined treatment of hydrometallury and thermometallurgy,and the precious metals were highly enriched,which provided good conditions for subsequent refining.