Abstract:

Selective leaching of arsenic and copper in copper smelting dust (referred to as “soot”) was investigated by Na₂S-NaOH leaching process with assistance of glow discharge plasma. Results showed that glow discharge plasma could enhance alkaline leaching capacity. The corresponding leaching ratios of arsenic and copper were reached to 92.52% and 7.76% at condition of 10 min discharge time, 500 W discharge power, 150 Pa discharge pressure, and 0.9 cm plate spacing. The leaching process reduced arsenic and copper content in soot from 7.11% to 0.45% and from 2.62% to 2.42%, respectively. XPS, XRD, and speciation analysis of heavy metals indicated that glow discharge plasma was able to oxidize As(Ⅲ) to As(Ⅴ) and Cu(Ⅰ) to Cu(Ⅱ), which As(Ⅴ) was more easily leached than As(Ⅲ) under alkaline condition. In conclusion, glow discharge plasma assisted Na₂S-NaOH leaching process proves to be an efficient way of removing both arsenic and copper from soot so the soot can be further utilized after toxic content reduction.

Key words: copper smelting dust, glow discharge plasma, leaching, selectivity, separation, arsenic and copper, oxidation

摘要：

采用辉光放电等离子体辅助Na₂S-NaOH浸取体系对铜冶炼烟灰（简称“烟灰”）进行研究，在放电时间10 min、放电功率500 W、放电压强150 Pa、极板间距0.9 cm的条件下，砷的浸出率为92.52%，铜的浸出率为7.76%，实现了砷和铜的有效分离。采用该方法处理后烟灰中的砷从7.11%降到0.45%，铜从2.62%变为2.42%，为烟灰的进一步利用创造了条件。XPS、XRD和重金属形态分析的综合分析结果表明，辉光能将As（Ⅲ）氧化为As（Ⅴ）、Cu（Ⅰ）氧化为Cu（Ⅱ），且在碱性条件下As（Ⅴ）比As（Ⅲ）更易浸出。因此，辉光放电预氧化有利于砷和铜在碱浸体系中选择性分离。

关键词: 铜冶炼烟灰, 辉光放电等离子体, 浸取, 选择性, 分离, 砷和铜, 氧化