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

作　　者：Xian Zhou Zhengfu Zhang Hui Yang 

机构地区：[1]School of Materials Science and Engineering,Kunming University of Science and Technology,Kunming,650093,China [2]Kunming Metallurgical Research Institute Co.,Ltd.,Kunming,650031,China

出　　处：《Frontiers of Environmental Science & Engineering》2024年第5期43-55,共13页环境科学与工程前沿（英文）

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).

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.AsO_(3)^(3−) was oxidized into AsO_(4)^(3−),which may form Ca–As or Fe–As precipitates.Cr_(2)O_(7)^(2−)was converted to CrO_(4)^(2−)under alkaline environment and then combined with OH−to form Cr(OH)3 precipitates.Mn^(2+)may react directly with dissolved silicate to form Mn_(2)SiO_(4) and also form Mn(OH)_(2) precipitates.The unstable Mn(OH)_(2) can be further oxidized to MnO_(2).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.

关 键 词：Heavy metals Cementitious materials Tin tailings STABILIZATION/SOLIDIFICATION Redox 

分 类 号：TG14[一般工业技术—材料科学与工程]