Abstract:

In view of the high content of free sulfuric acid in the copper leaching solution in hydrometallurgical process, neutralization treatment is required before copper extraction, which not only consumes large alkaline reagents and high operating cost, but also causes metal ion loss. In this paper, a solvent extraction process for sulfuric acid recovery was proposed and the mass transfer mechanism of the selective extraction process of trioctylamine (TOA) -n-octanol system was studied. The results showed that the third phase would be produced by hydration during TOA extraction of sulfuric acid. After adding n-octanol, the third phase can be avoided due to the formation of hydrophobic complexation \overline{({\mathrm{R}}_{\mathrm{3}}{\mathrm{N}\mathrm{H})}_{\mathrm{2}}{(\mathrm{A})}_{\mathrm{0.3}}({\mathrm{H}}_{\mathrm{2}}{\mathrm{O})}_{\mathrm{1.7}}\mathrm{S}{\mathrm{O}}_{\mathrm{4}}}. Under the conditions that the organic phase composition was 45% TOA+10% n-octanol +45% 260^# solvent oil, the ratio of O∶A (ratio of organic phase to aqueous phase) was 1∶1, the temperature was 25℃, the oscillation speed was 200r/min and the reaction time was 10min, the single-stage extraction rate of sulfuric acid reached 90.21% and the three-stage countercurrent extraction rate can achieve more than 99%. The extraction rates of Cu²⁺, Fe²⁺ and Zn²⁺ were less than 2.7%, 2.2% and 2.3%, respectively. The extraction process was an exothermic reaction and the calculated ∆H of the extraction reaction was -14.9kJ/mol.

Key words: extraction, separation, comprehensive recovery, copper hydrometallurgy, trioctylamine

摘要：

针对湿法炼铜浸出液中游离硫酸含量高的问题，提取铜前需进行中和处理，不仅碱性试剂消耗量大、作业成本高，还会造成金属离子损失的问题。本文提出采用溶剂萃取回收硫酸的工艺，研究了三辛胺（TOA）-正辛醇体系选择性萃取分离硫酸过程的传质机理。结果表明，TOA萃取硫酸的过程中会发生水化作用而产生第三相，加入正辛醇后，因形成疏水性络合体\overline{({\mathrm{R}}_{\mathrm{3}}{\mathrm{N}\mathrm{H})}_{\mathrm{2}}{(\mathrm{A})}_{\mathrm{0.3}}({\mathrm{H}}_{\mathrm{2}}{\mathrm{O})}_{\mathrm{1.7}}\mathrm{S}{\mathrm{O}}_{\mathrm{4}}}，避免了第三相的形成；在有机相构成为45% TOA+10%正辛醇+45% 260^#溶剂油、相比O∶A（有机相与水相之比）为1∶1、温度25℃、震荡速度200r/min、反应时间10min的条件下，硫酸单级萃取率达90.21%，三级逆流萃取率达99%以上，杂质离子Cu²⁺、Fe²⁺、Zn²⁺的萃取率分别小于2.7%、2.2%、2.3%；萃取过程为放热反应，通过计算得萃取反应的∆H为-14.9kJ/mol。

关键词: 萃取, 分离, 综合回收, 湿法炼铜, 三辛胺