Study On High Efficiency Extraction Of Indium By Microfluidic Technology

Indium is a kind of dissipated metal with excellent physical and chemical properties, it has being more and more widely used in various fields in recent years. The demand of Indium metal materials is growing rapidly, and it has become increasingly important in the national economy. Wet method is the most common way in Indium smelting production, while solvent extraction (SX) is one of the most important unit operations. But there are some drawbacks in the traditional SX methods, such as co-extracting of impurities, low extraction efficiency in single stage, large consumption of extractant, emulsification generation and hidden fire risks. Microfluidic technique has been developed for a wide range of applications as an efficient way for process intensification because of many advantages, such as high mass transfer efficiency, low energy consumption, and it provides a closed and safe system.In this paper, the application of Microfluidic technique in SX has been proposed. The extraction and separation efficiency of In3+from sulfate solution containing Fe3+by D2EHPA has been studied.Firstly, the dedicated microfluidic chips have been designed and the online liquid-liquid extraction and separation was achieved. The mechanism of liquid-liquid two-phase flow in microchannels has been studied. The calculation method of two-phase contact time and mass transfer rate of extracting indium have been discussed. In channel size of200microns or less, reaction of In3+extraction reached equilibrium in only7seconds, while Fe3+extraction percentage was2.75%.Then, microfluidic extraction was carried out in a Slit Interdigital Mico Mixer and the influences of process parameters on the extraction process and index have been studied by using response surface methodology for optimization and analysis. The effects of three preparation variables:the single flow rate, extract concentration and pH value were investigated, The optimum extraction and separation of In3+and Fe3+was obtained by using single flow rate of7.5mL/min, extract concentration of25%and pH value of0.4, the extraction percentage of In3+and Fe3+were99.96%and3.11%respectively. Excellent separation effect of indium and iron was obtained by one stage of microfluidic extraction reaction.In conclusion, utilizing the new microfluidic SX technology in hydrometallurgical solvent extraction process, which intends to make full use of the merit of micro-meter scale dispersion, mixing and transfer of microfluidic to realize the goal of "environmentally benign, efficient, safe and energy-saving" SX process.