Investigation on the Effect of Roasting and Leaching Parameters on Recovery of Gallium from Solid Waste Coal Fly Ash

• Main Authors: Jing Huang, Yingbin Wang, Guanxuan Zhou, Yu Gu
• Format: Article
• Language: English
• Published: MDPI AG 2019-11-01
• Series: Metals
• Subjects: gallium; coal fly ash; solid waste; naf; recovery; alkali roasting; acid leaching
• Online Access: https://www.mdpi.com/2075-4701/9/12/1251

Coal fly ash (CFA) provides important resources of gallium, which is regarded as an irreplaceable material in many technologies. A prospective roasting reagent assisted acid leaching process was proposed for the purpose of extracting gallium. The extraction efficiency of gallium by NaF (sodium fluoride) roasting followed by HNO₃ (nitric acid) leaching process was demonstrated. The effect of roasting temperature, roasting time, the NaF-CFA mass ratio, acid leaching temperature, acid leaching time, and acid concentration were investigated. The results revealed that under optimal conditions (roasting temperature of 800 °C, roasting time of 10 min, acid leaching in 2 mol/L HNO₃ for 1 h, and the NaF-CFA mass ratio of 0.75:1), 94% of gallium was extracted. Compared to previous studies, the process is a cost-effective method which can greatly shorten reaction time. It can reduce environmental pollution as it requires fewer acid reagents with low concentration and additives. It is expected to provide a method for the extraction of gallium from CFA.