Stabilization/solidification mechanisms of tin tailings and fuming slag-based geopolymers for different heavy metals

作     者：Xian Zhou Zhengfu Zhang Hui Yang 

作者机构：School of Materials Science and EngineeringKunming University of Science and TechnologyKunming650093China Kunming Metallurgical Research Institute Co.Ltd.Kunming650031China 

出 版 物：《Frontiers of Environmental Science & Engineering》 (环境科学与工程前沿（英文）)

年 卷 期：2024年第18卷第5期

页      面：43-55页

核心收录：

学科分类：0830[工学-环境科学与工程（可授工学、理学、农学学位）] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 

基　　金：financially supported by the National Key R&D Program of China(No.2019YFC1904202) the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,Kunming(No.CNMRCUKF20) the Center for Analysis and Testing of Kunming University of Science and Technology(No.2020P20171130007). 

主　　题：Heavy metals Cementitious materials Tin tailings Stabilization/solidification Redox 

摘      要：Tin mine tailings(TMT)and fuming slag(FS)contain many heavy metals(As,Cr,Cu,Zn and Mn)that cause severe pollution to the environment.Herein,geopolymers were prepared using TMT,FS and flue gas desulfurization gypsum(FGDG)to immobilize heavy metals,and their compressive strength and heavy metal leaching toxicity were investigated.It was first determined that T4F5(TMT:FS=4:5)sample exhibited the highest compressive strength(7.83 MPa).T4F5 achieved 95%immobilization efficiency for As and Cr,and nearly 100%for Cu,Zn and Mn,showing good immobilization performance.A series of characterization analyses showed that heavy metal cations can balance the charge in the geopolymer and replace Al in the geopolymer structure to form covalent bonds.In addition,about 2%–20%of heavy metal Fe was immobilized in hydration products,heavy metal hydroxides and non-bridging Si–O and Al–O coordination with silica-aluminate matrices.AsO33−was oxidized into AsO43−,which may form Ca–As or Fe–As precipitates.Cr2O72−was converted to CrO42−under alkaline environment and then combined with OH−to form Cr(OH)3 precipitates.Mn2+may react directly with dissolved silicate to form Mn2SiO4 and also form Mn(OH)2 precipitates.The unstable Mn(OH)2 can be further oxidized to MnO2.The heavy metal cations were immobilized in the silicoaluminate lattice,while the anions tended to form insoluble precipitates.These results may benefit the industry and government for better handling of TMT,FS and solid wastes containing the abovementioned five heavy metals.