细粒级铁尾矿粉的性能与改性机理研究

Research on the Performance and Modification Mechanism of Fine-grained Iron Tailings Powder

本文选取细粒级铁尾矿粉,并加入改性剂对其进行改性,研究改性铁尾矿粉的化学及矿物成分、细度、烧失量、需水量比及活性指数等相关性能,并与Ⅱ级粉煤灰性能进行比较,探究改性剂对铁尾矿粉的改性效果和改性机理。研究结果表明:细粒级铁尾矿粉的化学与矿物组成与粉煤灰相近,细粒级铁尾矿粉>45μm的颗粒含量为17.7%、烧失量为6.5%、改性后需水量比为97.2%,均满足国家Ⅱ级粉煤灰相关标准。碱类复合改性剂改性效果最好,改性铁尾矿粉3 d、7 d和28 d活性指数分别为95.6%、95.7%和89.3%,均高于Ⅱ级粉煤灰。随着改性铁尾矿粉比表面积增加,净浆抗压强度提高。铁尾矿粉经过改性处理后,界面处的SiO_(2)中的硅氧键会出现重组现象,发生重聚反应,宏观表现为抗压强度的提高。且铁尾矿粉颗粒粒径越小,这种重聚反应越显著,抗压强度的提升越明显。

In this paper,fine-grained iron tailings fines were selected and modified with modifiers.The chemical and mineral composition,fineness,burn-off,water demand ratio and activity index of the modified iron tailings powder were studied.The properties are compared with those of Class II fly ash to investigate the modification effect and modification mechanism of the modifier on the iron tailing powder.The results of the study show that the chemical and mineral composition of fine-grained iron tailings fines is similar to that of fly ash.The fine-grained iron tailings fines have a particle content of>45μm of 17.7%and a burn-off of 6.5%.The water demand ratio after modification was 97.2%,all of which met the relevant national standards for Class II fly ash.The best modification effect was achieved by the alkali composite modifier,with the activity index of modified iron tailing powder being 95.6%,95.7%and 89.3%at 3 d,7 d and 28 d respectively,all of which were higher than that of Class II fly ash.As the specific surface area of modified iron tailing powder increased,the compressive strength of net slurry increased.After the modified iron tailing powder is treated,the silica-oxygen bonds in SiO_(2) at the interface will be reorganised and reunification reaction will occur,which is macroscopically manifested as an increase in compressive strength.The smaller the particle size of iron tailing powder,the more significant this reunification reaction is,and the more obvious the increase of compressive strength.