粉煤灰资源利用:无机矿物改良剂对CFA源蛋白石/沙粒团聚体形成的影响  

Coal fly ash resource utilization:Effects of inorganic minerals amendments on CFA-originated opal/sand aggregates formation

作　　者：李为轮 王一霖 朱锋 周秋生 刘桂华 彭志宏 齐天贵 申雷霆 李小斌 LI Wei-lun;WANG Yi-lin;ZHU Feng;ZHOU Qiu-sheng;LIU Gui-hua;PENG Zhi-hong;QI Tian-gui;SHEN Lei-ting;LI Xiao-bin(School of Metallurgy and Environment,Central South University,Changsha 410083,China)

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha 410083,China

出　　处：《Journal of Central South University》2024年第4期1248-1264,共17页中南大学学报（英文版）

基　　金：Project(2022JJ40616)supported by the Natural Science Foundation of Hunan Province,China;Project(2022YFC2904404)supported by the National Key Research and Development Program of China。

摘　　要：粉煤灰碱法提铝的副产物-蛋白石(SiO_(2)·nH_(2)O,非晶质二氧化硅)具有很强的吸附性,是土壤中的次生/黏土矿物。将蛋白石与沙粒复配形成团聚体应用于沙漠化土壤修复,是一种前景广阔的大规模生态化处置方式。然而,由于无机矿物质的缺乏,该团聚体与自然土壤团聚体仍有差距。本文通过短期土培实验,研究了石灰石(CaCO_(3))、脱硫石膏(CaSO_(4)·2H_(2)O)、磷酸钙(Ca_(3)(PO_(4))_(2))、赤铁矿(Fe_(2)O_(3))、三水铝石(Al(OH)_(3))等无机矿物改良剂对团聚体形成、稳定以及孔隙特征的影响,并阐述了其内在的吸附机理。结果表明,五种改良剂中,只有石膏可有效降低团聚体的pH,且石膏对提升团聚体的保水效果最为显著,但石膏会增大电导率。改良剂均能促进团聚体的形成,提高机械稳定性,石膏、CaCO_(3)、Fe_(2)O_(3)有利于提高团聚体的水稳性。XRD/SEM/FT-IR/XPS等分析表明,无机矿物与沙子/蛋白石发生吸附作用,团聚体表面形成了有利于团聚体生成的无机矿物界面层。与CK相比,改良后的大团聚体(>0.25 mm)以孔径<80μm的孔隙和边界孔隙为主,孔隙率增加、孔隙数量和平均孔隙直径(MPD)减少、孔隙结构更致密、孔隙间的连通性提高以及孔隙网络更复杂。特别是经脱硫石膏改良后,微团聚体(<0.25μm)的MPD和2~5 nm中孔的数量增加,总孔隙体积和0~2 nm微孔的数量降低;而Ca_(3)(PO_(4))_(2)和Al(OH)_(3)增加了>15 nm介孔的数量。总之,作为土壤“骨架”的无机矿物有效改善了蛋白石/沙粒团聚体的物理结构,加速了团聚体的形成。因此,脱硫石膏优化了大聚集体的形成和稳定性。经脱硫石膏改良的团聚体可作为类土壤基质,加速退化的沙漠化土壤的生态重建。Opal(amorphous silica,SiO_(2)·nH_(2)O),a solid waste byproduct of the alkaline extracting alumina from coal fly ash,exhibits strong adsorption properties and is a secondary/clay mineral in the soil.Combining opal with sand to construct opal/sand aggregates for desertification soil remediation holds the potential for large-scale ecological disposal.Unfortunately,the aggregate structure still gaps from natural soil aggregates resulting from inorganic mineral deficiencies.Herein,the effects of five inorganic mineral amendments,limestone(CaCO_(3)),desulphurization gypsum(CaSO_(4)·2H_(2)O),hematite(Fe_(2)O_(3)),tricalcium phosphate(Ca_(3)(PO_(4))_(2))and gibbsites(Al(OH)_(3)),on aggregate formation,stabilization,and pore characteristics without the organic matters were investigated in short-term cultivation experiments.Meanwhile,associated adsorption mechanisms were elucidated.Results indicated only gypsum effectively reduced the aggregate’s pH,most enhanced water-holding capacity,albeit increased electrical conductivity.All amendments facilitated aggregate formation and mechanical-stability,with gypsum,CaCO_(3),and Fe_(2)O_(3) improving water stability.Various analysis techniques,including XRD,SEM,nano-CT,FT-IR,and XPS,provided insights into the physisorption and chemisorption of minerals onto sand/opal,generating interfaces conducive to aggregation.Compared to CK(control check,without amendment addition),amended macroaggregates demonstrated increased porosity,reduced pore quantity and mean pore diameter(MPD),denser pore structure,improved interpore connectivity,and more complex pore networks,dominated by<80μm diameters and boundary pores.Notably,desulphurization gypsum elicited the most significant variations,increasing MPD of microaggregates and 2-5 nm mesopores,and decreasing total pore volume and 0-2 nm micropores,while Ca_(3)(PO_(4))_(2) and Al(OH)_(3) improved>15 nm mesopores.Overall,inorganic minerals,the“skeleton”of soil,effectively upgraded opal/sand aggregates’physical structure and accelerated a

关 键 词：无机矿物改良剂 蛋白石/沙粒团聚体 脱硫石膏 团聚体稳定性 孔隙特征 沙漠化土壤修复 

分 类 号：TQ1[化学工程]