Research Progress and Experimental Evaluation of Refining Process Technology for High-Impurity Crude Silver
YANG Shaobo
XU Jianying
WANG Xueshuang
DING Zhichao
WEN Yongkun
Abstract：To address the challenges in traditional electrolytic refining of crude silver containing high levels of impurities such as selenium,tellurium,and bismuth—including anode passivation,low-grade cathode silver powder,and the need for repeated electrolysis—this study systematically investigated three technical approaches:additive-based removal during casting,wet pretreatment,and electrolytic process optimization.Through experimental evaluation,the efficient removal of tellurium and selenium using a sodium carbonate-sodium nitrate composite additive(with a mass ratio of 1∶1-2∶1 and addition amount of 1.5%-2.0%)was confirmed.The contradictions of the"acid leaching-chlorination precipitation of silver-iron powder reduction"wet process—thorough impurity removal but complex procedures and low recovery rates—were revealed.Moreover,the feasibility of a novel electrolytic system characterized by"high acidity in the primary stage for lead dissolution and high acidity with low copper ion concentration in the secondary stage"was highlighted.This system increased the purity of cathode silver powder to above 99.996%and raised the tolerance limits for tellurium and selenium to 0.004 2%and 0.002 8%,respectively.Combined with the precise control of an automated casting system,this research provides an efficient and low-cost purification strategy centered on"additive pretreatment+electrolytic parameter optimization"for silver refineries with limited pyrometallurgical support.
Keywords：crude silver refininghigh impurity tolerancesodium carbonate-sodium nitrate additivewet pretreatmenthigh-acidity and low-copper ion electrolysisautomated casting
Publication Date：2025-10-20
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：3( 41-43 )