Experimental Study On Tailings Cemented Filling Material With High Concentrations

With the continuous exploitation of mines, a lot of tailings was emitted, not only taking up a lot of land, but also polluting the environment, at the same time mining goaf was formed, if mined-out area was not filled timely, which could cause a collapse in mined-out area and bring potential safety hazard to mining and ground building. In order to solve the above problems, research of taiings cemented filling material with high concentration provided a kind of way.Total tailings was used as aggregate, at first this paper studied the ratio and properties of cement tailings cemented filling material, cement-sand ratio was 1:10, solid concentration was 78%, orthogonal experiment was carried out, range analysis and variance analyses methods were employed to study the fluidity, shrinkage ratio of tailings cemented filling material and mechanical properties under the influence of gypsum total mass fraction, bassanites:dihydrate gypsum and lime fraction. The optimal mixing proportion of cement tailings cemented filling material was determined.Then it studied the ratio and properties of no cement tailings cemented filling material, single factor experiment was carried to study the fluidity, shrinkage ratio of tailings cemented filling material and mechanical properties under the influence of cement-sand ratio, solid concentration, fly ash proportion. On this basis, then studying mechanical properties and shrinkage ratio of tailings cemented filling material under the influence of dihydrate gypsum, bassanites and lime. The optimal mixing proportion of no cement tailings cemented filling material was determined. The main conclusions are as follows:(1) Cement tailings cemented filling material, The main factors that influencing fluidity loss was the proportion of lime and the ratio of bassanite and dihydrate gypsum.The most important factor that affected shrinkage ratio was the ratio of bassanite and dihydrate gypsum, the secondary factor was proportion of total gypsum. The most important factor that affected compressive strength of three days、seven days and twenty-eight days was the ratio of bassanite and dihydrate gypsum(2) The optimal formulation of experiment of cement tailings cemented filling material was that slag 60%, cement 15%, bassanites 10%, dihydrate gypsum 10% and lime 5%. The slump of an hour later still could meet the requirements of pumping The compressive of three days of tailings cemented filling material was 0.99 MPa, the compressive of twenty-eight days was 4.68MPa. Shrinkage ratio reached 3.5%, meeting the requirement of strength and tight filling.(3) No cement tailings cemented filling material, with the increase of solid concentration, shrinkage ratio decreased gradually. The increase of fly ash was beneficial to the increase of slurry slump,the reduction of the dosage of fly ash let shrinkage ratio of filling body decrease; the increase of cement-sand ratio contributed to improve slurry fluidity.(4) No cement tailings cemented filling material, dihydrate The increase of proportion of dihydrate FGD gypsum helped shrinkage ratio of filling body to be lower and the growth of the early strength of filling body; The increase of the proportion of phosphogypsum helped later strength to increase and decrease early strength; the increase of bassanites content let shrinkage ratio of filling body be lower, the appropriate dosage contributed to the improvement of early strength; A small amount of lime was beneficial to the improvement of the strength of filling body...