覆岩隔离注浆充填浆液减水改性试验研究

Experimental study on water reduction and modification of filling slurry by isolated grouting in overlying

覆岩隔离注浆充填技术是实现煤矿减损开采与固废减排的绿色开采方法,而浆液流动性是影响注浆充填效率、效果与安全性的重要因素。高水灰比浆液流动性好,但其需水量大、脱水量高,易导致充填效率低、缺水矿区应用受限、构造复杂区影响安全生产等问题。试验研究了粉煤灰浆液、矸石粉浆液中添加木质素磺酸钠(21F4型)、聚羧酸(HLX型)、萘系(FDN-C型)减水剂后,对配置用水、压实泌水、浆液析水率及浆液絮凝结构的影响。结果表明:聚羧酸减水剂减水效果最为显著,当其添加量为1.2%时,粉煤灰、矸石粉浆液的配置用水分别减少25%和35%;压实泌水分别减少60%和40%。研究发现,浆液需水量大的原因是浆液中存在大量絮凝结构,该结构束缚了部分自由水,减水剂通过打破絮凝结构提高自由水占比进而提高浆液的流动性。提出的粉煤灰和矸石粉浆液减水改性方法,可提高覆岩隔离注浆充填效率、效果与安全性,为该方法在缺水矿区的应用提供重要支撑。

The isolated grouting and filling technology of overlying strata is a green mining method to re-alize the reduction of mining loss and emission reduction of solid waste in coal mines,and the fluidity of slurry is an important factor affecting the efficiency,effect and safety of grouting and filling.Although the slurry with high water-cement ratio has good fluidity,it needs a large amount of water and dehydration,which leads to problems such as low filling efficiency,limited application in water-deficient mining areas,and complex structure areas affecting safety production.The effects of sodium lignosulfonate(21F4 type),polycarboxylic acid(HLX type)and naphthalene series(FDN-C type)water reducers added to fly ash slurry and gangue powder slurry on water allocation and compaction bleeding were studied experimentally,and the effects of water reducers on water separation rate and flocculation structure of slurry were analyzed.The results show that the polycarboxylate superplasticizer has the most remarkable water-reducing effect.When the dosage is 1.2%,the preparation water of fly ash and gangue powder slurry is reduced by 25%and 35%respectively,and the compaction bleeding is reduced by 60%and 40%respectively.It is found that the reason for the large water demand of slurry is that there are a large number of flocculation structures in the slurry,which bind some free water.The superplasticizer improves the proportion of free water by breaking the flocculation structure,thus improving the fluidity of the slurry.The water-reducing modification method of fly ash and gangue powder slurry proposed in this paper improves the efficiency,effect and safety of isolated grouting flling in overlying strata,and provides an important way for the application of this method in water-deficient mining areas.