离子吸附型稀土矿在黑曲霉发酵液中的浸出效果及界面特性研究

Leaching Effect and Surface Characteristics of Ion−adsorbed Rare Earth Ores in Aspergillus Niger System

为了探究离子吸附型稀土矿生物浸出过程规律,指导高效溶浸剂的开发和浸出工艺优化,采用摇瓶振荡实验、接触角测量、开路电压、Tafel和电化学阻抗测试分析了离子吸附型稀土矿在黑曲霉发酵液中的浸出特性。结果表明:与温度相比,稀土浸出率受发酵液体积占比和时间影响更大,且随着发酵液体积占比和时间的增加而升高,当发酵液体积占比为75%、温度为25℃、时间为30 min时,La、Ce和Y的浸出率分别达到95.84%、94.44%和96.73%。矿石中铝硅酸盐矿物出现微弱溶解。矿石与发酵液的接触角随发酵液体积占比升高而降低,随时间增加而不断减小:液滴铺展5 s时纯水中接触角最小为12.53°,发酵液体积占比25%、50%、75%和100%时接触角分别为16.38°、33.52°、43.78°和46.58°。随发酵液体积占比的增加,开路电压和腐蚀电压升高,黏土矿物溶解的难度降低。离子吸附型稀土矿生物浸出受溶液中溶质扩散、固液界面双电子层电子传递和界面副产物三种阻力。

To investigate the law of bioleaching process of ion−adsorbed rare earth ores,and to guide the development of efficient solvent and optimization of leaching process.The leaching characteristics of ion−adsorbed rare earth ores in Aspergillus niger fermentation system were analyzed by shaking bottle experiment,contact angle measurement,open circuit voltage,Tafel,and electrochemical impedance test.The results showed that the leaching rate of rare earths was more affected by the volume percentage of fermentation liquor and time compared with the temperature,and increased with the increase volume percentage of fermentation liquor and time.The leaching rates of La,Ce,and Y reached 95.84%,94.44%,and 96.73%,respectively,when the volume percentage of fermentation liquor was 75%,the temperature was 25℃,and the time was 30 min.The aluminum silicate minerals in the ore showed weak dissolution.The contact angle between the ore and the solution decreased with increasing volume percentage of fermentation liquor and kept decreasing with increasing time.When the droplets spread out for five seconds,the contact angle was minimum 12.53°in pure water,and 16.38°,33.52°,43.78°,and 46.58°in 25%,50%,75%,and pure fermentation liquor,respectively.With the increase volume percentage of fermentation liquor,the open circuit voltage and corrosion voltage increase sequentially,and the difficulty of clay mineral dissolution decreases sequentially.The bioleaching of ion−adsorbed rare earth ores was subject to the triple resistance of diffusion of solutes in solution,electron transfer from the interfacial double electron layer,and interfacial by−products.