Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF2 Assistance and Process Optimization

Deshun Kong; Zihan Zhou; Shuojiang Song; Rongli Jiang

doi:10.3390/ma16020499

Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF₂ Assistance and Process Optimization

Materials (Basel). 2023 Jan 4;16(2):499. doi: 10.3390/ma16020499.

Authors

Deshun Kong^{1

2}, Zihan Zhou², Shuojiang Song^{1

2}, Rongli Jiang²

Affiliations

¹ Guizhou Provincial Key Laboratory of Coal Clean Utilization, School of Chemistry and Materials Engineering, Liupanshui Normal University, Liupanshui 553004, China.
² School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221016, China.

Abstract

To reveal how CaF₂ improves the dissolution ratios of aluminum and iron ions in coal gangue, CaF₂ and hydrochloric acid are used to extract Al³⁺ and Fe³⁺ from the coal gangue calcined powder. The leaching ratios of Al³⁺ and Fe³⁺ are measured, and the filter residues are analyzed by BET, XRD, and SEM. The results show that adding 3% CaF₂ could increase the extraction ratio of Al³⁺ from 62.96% to 92.10% under optimized conditions, and that of Fe³⁺ is increased from 85.12% to 95.73%. The mechanism of CaF₂ as an auxiliary to improve the leaching ratio of Fe³⁺ is that HF reacts with the thin layers of gangue calcined powder containing silica to form soluble SiF₄, thus forming pores that promote the diffusion of H⁺ and inner ions, improving the leaching ratios of Al³⁺ and Fe³⁺. Finally, the CaF_2-assisted acid leaching process is optimized. The results showed that it is efficient and feasible to extract Al³⁺ and Fe³⁺ with the assistance of CaF₂ and that HF has a catalytic effect in the reaction system. This work provides a reference for the next step of actual production.

Keywords: CaF2; acid leaching; coal gangue; extraction of aluminum and iron ions.

Abstract

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