减水剂与粉煤灰对全尾砂胶结充填料浆流变性能的影响

全尾砂胶结充填料浆流变性能直接影响其工作性能。采用Brookfield RST-SST型流变仪定量分析了聚羧酸(PC)、萘系(PNS)和三聚氰胺系(PMS)3种类型高效减水剂与粉煤灰单掺和复掺时对料浆流变性能的影响。结果表明:无论减水剂类型,掺入料浆后均可降低其屈服应力和塑性黏度且减水剂掺量越高降低幅度越大,料浆流变性能改善效果越好。3种类型减水剂对料浆流变性能改善程度存在差异,其中PC作用效果最好。减水剂的改性效果随着胶结料的持续水化而出现缓慢退化;随粉煤灰掺量的增加,料浆的屈服应力和塑性黏度呈整体降低趋势,其作用机理主要源于"形态效应";减水剂与粉煤灰两者在改善料浆流变性能方面具有协同效应,复掺后可显著改善料浆的流变性能,效果明显优于单掺改性效果。

Effects of superplasticizers and fly ash on rheological properties of cemented tailings backfill

The workability of cemented tailings backfill (CTB) is significantly affected by its rheological properties. The influence of fly ash and superplasticizers (SPs) including polycarboxylate (PC), polynaphthalenesulfonate(PNS) and polymelaminesulfonate(PMS) on the rheological properties of CTB mixtures was quantitatively analyzed by using Brookfield RST-SST rheometer in this paper. The results show that regardless of SP type, the addition of superplasticizer will reduce the yield stress and plastic viscosity of CTBs, and the rheological properties are improved with increasing SP dosage. PC is found to be the most effective SP in improving the rheological properties of fresh CTB. However, as hydration time increases, the effect of SPs on the yield stress and plastic viscosity of CTB decreases. With the increase of fly ash content, the yield stress and plastic viscosity of CTBs also show a decreasing trend, due to "morphological effect" of fly ash. The mixture of SP and fly ash has a synergistic effect on the rheological properties of CTB, the modification effect of which is much better compared to that of single mix of SP or fly ash.