水泥协同多固废固化铬铁渣充填材料的制备及性能研究

Study on Preparation and Properties of Cement Synergistic Multi-Solid Waste Solidified Ferrochrome Slag Filling Material

为解决铬铁渣堆存占地面积大、污染土壤与水体、资源化利用水平低的问题,以矿渣-石灰-脱硫石膏-水泥熟料协同激发制备四元体系新型充填材料,揭示料浆流变性能、力学性能的变化规律,结合扫描电镜阐述充填体水化机理,通过毒性浸出试验探明充填材料固化/稳定化机理。结果表明:料浆流变曲线符合Hershel-Bulkley模型,随着减水剂掺量的增加,料浆屈服应力显著降低,铬铁渣掺量是影响料浆屈服应力变化的非显著性因素。随着铬铁渣掺量的增加,充填体抗压强度呈降低趋势;减水剂掺量从0.1%增加至0.4%的过程中,抗压强度呈先上升后降低的趋势;随着脱硫石膏掺量的增加,早期强度呈上升趋势,后期强度呈先上升后降低的趋势;石灰掺量从5%增加至20%的过程中,抗压强度呈快速上升趋势,且掺量越大,上升幅度越明显。当铬铁渣∶矿渣∶石灰∶脱硫石膏∶水泥∶减水剂为30∶30∶20∶8∶12∶0.3,抗压强度达最优值。充填体微观结构形貌以柱状钙矾石和团聚状C-S-H凝胶为主,二者紧密黏结形成整体。水化28 d充填体毒害离子浸出浓度满足《污水综合排放标准》(GB 8978—1996)要求,对Cr^(3+)和Cr^(6+)具备显著的固化/稳定化效果。

In order to solve the problems of large storage area of chromite slag,pollution of soil and water,and low level of resource utilization,a new filling material of quaternary system was prepared by synergistic excitation of slag-lime-desulfurization gypsum-cement clinker,and the rheological properties and mechanical properties of slurry were revealed.Combined with scanning electron microscopy,the hydration mechanism of filling body was expounded,and the solidification/stabilization mechanism of filling material was proved by toxicity leaching test.The results show that the rheological curve of the slurry conforms to the Hershel-Bulkley model.With the increase of the content of water reducing agent,the yield stress of the slurry decreases significantly,and the content of ferrochrome slag is a non-significant factor affecting the yield stress of the slurry.With the increase of ferrochrome slag content,the compressive strength of filling body decreases.In the process of increasing the amount of water reducing agent from 0.1%to 0.4%,the compressive strength increases first and then decreases.With the increase of desulfurization gypsum content,the early strength shows an upward trend,and the later strength shows a trend of first increasing and then decreasing.When the lime content increases from 5%to 20%,the compressive strength shows a rapid upward trend,and the larger the lime content,the more obvious the increase degree.When the chromite slag:slag:lime:desulfurization gypsum:cement:water reducing agent is 30:30:20:8:12:0.3,the compressive strength reaches the optimal value.The microstructure of the filling body is dominated by columnar ettringite and agglomerated C-S-H gel,which are closely bonded to form a whole.The leaching concentration of toxic ions in the 28 d hydration filling body meets the requirements of Integrated Wastewater Discharge Standard(GB 8978-1996),and has a significant solidification/stabilization effect on Cr^(3+) and Cre^(6+).