Inorganic Chemicals Industry ›› 2023, Vol. 55 ›› Issue (4): 76-83.doi: 10.19964/j.issn.1006-4990.2022-0386

• Environment·Health·Safety • Previous Articles     Next Articles

Preparation of poly-aluminum chloride from acid leaching liquor of red mud-coal gangue activated by sodium salt

WANG Lijuan1,2(), YAN Kezhou1(), GUO Zhiqiang1, ZHAO Zhonghe3, GUO Yanxia1,2, CHENG Fangqin1,2   

  1. 1. Institute of Resources and Environmental Engineering,State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Shanxi University,Taiyuan 030006,China
    2. College of Environmental;and Resource Sciences of Shanxi University,Taiyuan 030006,China
    3. Shanxi Dadi Environment;investment Holdings Company,Taiyuan 030032,China
  • Received:2022-06-24 Online:2023-04-10 Published:2023-04-13

Abstract:

Poly-aluminium chloride(PAC) was prepared from the acid leaching liquor of sodium activated red mud-coal gangue activated by sodium salt through evaporation crystallization and alkalization polymerization.Firstly,the effect of impurity ion concentrations in acid leaching liquor on the quality of PAC was studied,and the impurity ion was selectively removed through evaporation crystallization.Then the effects of polymerization conditions including temperature,time and adding rate of alkalizing agent on the basicity and Al2O3 content of PAC were evaluated.The results showed that the basicity and Al2O3 content of the prepared PAC were qualified according to national standard GB/T 22627—2022 when Na+ concentration was lower than 0.5 mol/L in the acid leaching liquor.Based on the solubility difference of NaCl,AlCl3,CaCl2 and FeCl3,sodium could be selectively removed by evaporation crystallization,and the concentration of Na+ in the acid leaching solution could be controlled below 0.5 mol/L.The PAC product meeting the quality requirements of GB/T 22627—2022 could be prepared by evaporating the crystallization mother liquor and then passing through the appropriate polymerization conditions(polymerization temperature was 80 °C,polymerization time was 120 min,and alkalizing agent addition rate was 8.0 mL/min).The flocculation performance of PAC obtained from the acid leaching liquor for domestic sewage treatment was better than that of commercial flocculant,and the removal efficiencies of COD,turbidity and UV254 were 85.62%,76.36% and 70.31%,respectively.

Key words: red mud, coal gangue, evaporation crystallization, PAC, flocculation performance

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