WANG W , RUI D H, LI M P,et al.Experimental study on dealkalization of red mud by freeze-thaw and washing[J].Journal of Henan Polytechnic University(Natural Science) ,2023,42(5):169-175.

doi:10.16186/j.cnki.1673-9787.2021110097

Received:2021/11/23

Revised:2021/12/31

Published:2023/09/25

Experimental study on dealkalization of red mud by freeze-thaw and washing

WANG Wei1, RUI Dahu1, LI Mingpu1, ZHANG Haiyang2, WANG Shuren1

1.School of Civil Engineering，Henan Polytechnic University，Jiaozuo  454000，Henan，China;2.No.2 Institute，Geological & Mineral Resources Survey of Henan，Zhengzhou  450001，Henan，China

Abstract:The comprehensive utilization of red mud in many fields is limited because of its strong alkalinity. Taking the red mud provided by a Bayer alumina plant in Henan Province as the research object，this paper put forward the dealkalization scheme of freeze-thaw combined with chemical washing.That is，the original structure of soil particles was repeatedly frozen and thawed， and the combined alkali crystal structure was destroyed to further release the structural alkali wrapped in the red mud，which can increase the contact area. Freeze-thaw and washing experiment was carried out and the effects of freeze-thaw on the structure of red mud and the effects of oxalic acid concentration and freeze-thaw times on the dealkalization rate of red mud were investigated. At the same time，the mechanism of freeze-thaw and washing dealkalization was analyzed from the micro level by XRD phase analysis，particle size analysis and electron microscope scanning. The results showed that freeze-thaw could destroy the crystal structure of bound alkali in red mud particles，which was conducive to the contact reaction between leaching solution and bound alkali，so as to improve the dealkalization rate.Under the condition of oxalic acid concentration of 0.5 mol/L and twice freeze-thaw and washing，the dealkalization rate of red mud could reach 94.96%，which was 14.26% higher than that under normal temperature. This study provided a new idea for the dealkalization of red mud in the alternating phenomenon of freezing and thawing in seasonal frozen soil area in the future.

Key words:red mud;freeze-thaw;chemical washing;dealkalization

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