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

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 CaF2-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.

Research Progress of Coal Gangue Modification Method and Its Resource and Environment Utilisation

“…煤矸石主要由岩石、煤的残 余以及煤炭开采过程中引入的杂质组成, 这些成分的比 例根据采矿地点和方法的不同而有所变化 [4][5] . 煤矸石 的化学成分主要包括硅酸盐、 铝酸盐和少量的铁氧化物, 其中硅和铝的含量最高 [6][7][8][9] . 在微观结构上, 煤矸石呈多 孔状, 这使得它具有潜在的吸附能力 [10][11] .…”

Effects of a Cellulose Aerogel Template on the Preparation and Adsorption Properties of Coal Gangue-Based Multistage Porous ZSM−5

“…The research showed that with CG as the raw material, an environmentally friendly adsorbent calcium silicate hydrate could be prepared, effectively removing metals from aqueous solutions through different mechanisms. Kong et al [17] studied the extraction of iron and aluminum from CG. Liang et al [18] synthesized NaX zeolite from CG and explored its removal effect and mechanism of Cd 2+ and Cu 2+ .…”