锌粉置换渣中镓、锗的强化浸出试验研究

Experimental Study on the Enhanced Leaching of Gallium and Germanium from Zinc Powder Replacement Residues

针对锌粉置换渣提取Ga、Ge过程浸出效果不佳的问题,本研究首先开展了常压硫酸浸出试验,考察硫酸浓度、反应温度、液固比、反应时间对Ga、Ge浸出率的影响,并对浸出过程进行了动力学分析;而后分别尝试了还原浸出(先后以Na_(2)SO_(3)、SO_(2)为还原剂)、硫酸化焙烧-水浸两种工艺,对锌粉置换渣开展了Ga、Ge强化浸出试验。结果表明:常压硫酸浸出工艺在硫酸浓度150 g/L、反应温度90℃、液固体积质量比5 mL/g、反应时间4 h、搅拌转速400 r/min的适宜条件下,Ga、Ge浸出率分别为68.4%、61.7%;酸浸渣主要物相为PbSO_(4)和ZnAl_(2)O_(4),增加酸度可促使残留的黄钾铁矾、铅铝矾进一步溶出;Ga和Ge常压硫酸浸出过程主要受内扩散控制,反应表观活化能分别为18.06 kJ/mol和16.02kJ/mol。对一段常压硫酸浸出渣进行二段还原强化浸出,以Na_(2)SO_(3)为还原剂,在50 g/L H_(2)SO_(4)+3 g/L Na_(2)SO_(3)条件下,Ga、Ge浸出率达89.4%和70.1%;以SO_(2)为还原剂,在SO_(2)分压0.3 MPa、硫酸浓度50 g/L、反应温度110℃、、反应时间3 h条件下,Ga、Ge浸出率达88.9%和86.7%。硫酸化焙烧-水浸工艺对锌粉置换渣中Ga的浸出效果改善明显,但对Ge浸出不利,酸渣体积质量比宜为1/2.5 mL/g,并在焙烧温度300℃、焙烧时间3 h、水浸温度80℃、液固体积质量比5 mL/g、浸出时间2 h的条件下,Ga浸出率可提高到89.1%。

To solve the problem of poor leaching effeciency in the extraction process of gallium and germanium from zinc powder replacement residues,this study first conducted atmospheric sulfuric acid leaching tests,investigating the influence of sulfuric acid concentration,reaction temperature,liquid-to-solid ratio,and reaction time on the leaching rates of Ga and Ge,and carried out kinetic analysis of the leaching process.Then,the enhanced leaching tests of Ga and Ge from zinc powder replacement residues were conducted by reduction leaching(sequentially using Na_(2)SO_(3) and SO_(2) as reducing agents)and sulfation roasting-water leaching.The results show that under the optimum conditions of sulfuric acid concentration of 150 g/L,reaction temperature of 90℃,liquid-to-solid ratio of 5 mL/g,reaction time of 4 h,and stirring speed of 400 r/min,the leaching rates of Ga and Ge by atmospheric sulfuric acid leaching are 68.4%and 61.7%,respectively.The main phases in the acid leaching residue are PbSO_(4) and ZnAl_(2)O_(4),and increasing acidity can further dissolve the residual jarosite and lead aluminum sulfate.The atmospheric sulfuric acid leaching processes of Ga and Ge are mainly controlled by internal diffusion with the apparent activation energies of the reactions of 18.06 kJ/mol and 16.02 kJ/mol,respectively.The leaching residue from the first stage of atmospheric sulfuric acid leaching underwent a second-stage reduction enhanced leaching.Using Na_(2)SO_(3) as the reducing agent,Ga and Ge leaching rates reach 89.4%and 70.1%,respectively,under the conditions of 50 g/L H_(2)SO_(4) and 3 g/L Na_(2)SO_(3).And using SO_(2) as the reducing agent,Ga and Ge lea-ching rates reach 88.9%and 86.7%,respectively,under the conditions of SO_(2) partial pressure of 0.3 MPa,sulfuric acid concentration of 50 g/L,reaction temperature of 110℃,and reaction time of 3 h.The sulfation roasting-water leaching process significantly improves the Ga leaching efficiency from zinc powder replacement residues,while it is unfavorable to the leaching of Ge.Under the optimum conditions of acid residue volume-to-mass ratio of 1/2.5 mg/L,roasting temperature of 300℃,roasting time of 3 h,water leaching temperature of 80℃,liquid-to-solid ratio of 5 mg/L,and leaching time of 2 h,the leaching rate of Ga increases to 89.1%.