Rapid conversion of alkaline bauxite residue through co-pyrolysis with waste biomass and its revegetation potential  

作　　者：Yujun Wu Yufei Zhang Qihou Li Jun Jiang Yifan Jiang Shengguo Xue 

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha 410083,China [2]Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution,Changsha 410083,China

出　　处：《Journal of Environmental Sciences》2023年第5期102-113,共12页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.42030711,42177391);the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20200177).

摘　　要：The extreme alkalinity of bauxite residue(BR)leads to difficulty with its reuse.Alkaline leachate and dust generation during the stacking process can pollute surrounding soil,air and water.In this work,co-pyrolysis of bauxite residue and sawdust was applied to rapidly produce a soil-like matrix that met the conditions for plant growth as demonstrated by ryegrass pot experiments.The present study aimed to characterize the detailed changes in physicochemical,mineral weathering,and microbial communities of the pyrolyzed BR with different ratios of saw dust after plant colonization for 2 months.With increasing sawdust addition during co-pyrolysis,the pH of BR decreased from 11.21 to 8.16,the fraction of macro-aggregates 0.25-2 mm in the water-stable agglomerates increased by 29.3%,and the organic carbon concentration increased from 12.5 to 320 mg/kg,whilst facilitating the degree of humification,which were all beneficial to its revegetation performance.The backscattered electron-scanning electron microscope-energy-dispersive X-ray spectrometry(BSE-SEM-EDS)results confirmed the occurrence of sodalite and calcite weathering on aggregate surfaces,and X-ray photoelectron spectroscopy(XPS)results of surface Al and Si compounds identified that some weathering products were clay minerals such as kaolinite.Furthermore,bacterial community composition and structure shifted towards typical soil taxonomic groups.These results demonstrate soil development of treated BR at an early stage.The technique is a combination of alkalinity regulation and agglomerate construction,which accelerates soil formation of BR,thus proving highly promising for potential application as an artificial soil substitute.

关 键 词：Bauxite residue Waste sawdust CO-PYROLYSIS Resource reuse Soil formation 

分 类 号：X171.4[环境科学与工程—环境科学] X753