Separation process and mechanism of lithium and gallium by microwave enhanced leaching of high-alumina coal ash.pdf

SHENYONG LI, Hebei University of Engineering
Qian Wang, Hebei University of Engineering
Shuai Kang, Hebei University of Engineering
Wei Pang, Hebei University of Engineering

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Separation process and mechanism of lithium and gallium by microwave enhanced leaching of high-alumina coal ash Authors Dr. SHENYONG LI - China - Hebei University of Engineering Ms. Qian Wang - China - Hebei University of Engineering Mr. Shuai Kang - China - Hebei University of Engineering Ms. Wei Pang - China - Hebei University of Engineering Mr. Longlong Hao - China - Hebei University of Engineering Prof. Shenjun Qin - China - Hebei University of Engineering Abstract With the increasing demand and supply shortage of rare metals, fly ash may become an ideal alternative source for strategic key metals such as lithium and gallium. In this study, the nature and elemental distribution of high-alumina fly ash were investigated, and the separation method of lithium and gallium via high-efficiency roasting, microwave leaching and precipitation treatment was proposed. The transformation and migration mechanism of elements during roasting were studied by thermodynamic simulation, and the kinetic behavior of leaching process of lithium and gallium was studied in detail, The co-precipitation separation process was discussed. It provides theoretical basis and technical support for multi-element collaborative extraction and high value-added utilization of fly ash.The main conclusions are as follows. (1) The mineral composition of power plant fly ash is mainly mullite and quartz, followed by corundum, and lithium and gallium elements tend to exist in fine-grained fly ash, and are relatively enriched in non-magnetic components; the step-by-step chemical extraction study shows that lithium and gallium in fly ash are mainly in the glassy phase and mullite-quartz phase. (2) The leaching rates of lithium and gallium were lower in direct water bath and direct microwave acid leaching. After roasting, the leaching rates of lithium and gallium reached 96% and 94% at 80℃ and 3 mol•L-1 hydrochloric acid for 60min. While microwave digestion only took 10min for the same leaching rate. (3) The acid leaching process of roasted fly ash conforms to the shrinkage unreacted kernel model. Within 2~10 min, the leaching process is controlled by chemical reaction, and by diffusion in 20~60 min. (4) The co-precipitation conditions were molar ratio of 7, pH of 7, reaction at room temperature for 10 minutes, the precipitation rates of aluminum and lithium reached 99% and 92%, respectively, and the product was confirmed as LiC1•2A1(OH)3•xH2O by characterization.

 
May 15th, 10:30 AM May 15th, 11:00 AM

Separation process and mechanism of lithium and gallium by microwave enhanced leaching of high-alumina coal ash.pdf

Grand Rapids, Michigan

Separation process and mechanism of lithium and gallium by microwave enhanced leaching of high-alumina coal ash Authors Dr. SHENYONG LI - China - Hebei University of Engineering Ms. Qian Wang - China - Hebei University of Engineering Mr. Shuai Kang - China - Hebei University of Engineering Ms. Wei Pang - China - Hebei University of Engineering Mr. Longlong Hao - China - Hebei University of Engineering Prof. Shenjun Qin - China - Hebei University of Engineering Abstract With the increasing demand and supply shortage of rare metals, fly ash may become an ideal alternative source for strategic key metals such as lithium and gallium. In this study, the nature and elemental distribution of high-alumina fly ash were investigated, and the separation method of lithium and gallium via high-efficiency roasting, microwave leaching and precipitation treatment was proposed. The transformation and migration mechanism of elements during roasting were studied by thermodynamic simulation, and the kinetic behavior of leaching process of lithium and gallium was studied in detail, The co-precipitation separation process was discussed. It provides theoretical basis and technical support for multi-element collaborative extraction and high value-added utilization of fly ash.The main conclusions are as follows. (1) The mineral composition of power plant fly ash is mainly mullite and quartz, followed by corundum, and lithium and gallium elements tend to exist in fine-grained fly ash, and are relatively enriched in non-magnetic components; the step-by-step chemical extraction study shows that lithium and gallium in fly ash are mainly in the glassy phase and mullite-quartz phase. (2) The leaching rates of lithium and gallium were lower in direct water bath and direct microwave acid leaching. After roasting, the leaching rates of lithium and gallium reached 96% and 94% at 80℃ and 3 mol•L-1 hydrochloric acid for 60min. While microwave digestion only took 10min for the same leaching rate. (3) The acid leaching process of roasted fly ash conforms to the shrinkage unreacted kernel model. Within 2~10 min, the leaching process is controlled by chemical reaction, and by diffusion in 20~60 min. (4) The co-precipitation conditions were molar ratio of 7, pH of 7, reaction at room temperature for 10 minutes, the precipitation rates of aluminum and lithium reached 99% and 92%, respectively, and the product was confirmed as LiC1•2A1(OH)3•xH2O by characterization.