Feasibility Study On Application Of Phosphorus Tailings Filling Material In Goaf Treatment

Since the mining of Xinpu Phosphate Mine in Lianyungang City,Jiangsu Province,a large-scale underground mined-out area has been formed.There have been multiple collapse on the surface.Moreover,a large amount of tailings generated during the mining process occupies land resources,causing problems such as dust pollution.In this paper,a feasibility study was carried out for the purpose of using grouting materials prepared by phosphor tailings to fill underground mined-out areas to eliminate hidden dangers of geological hazards and reduce geological environmental pollution.Firstly,the geological environment conditions and the distribution of the mined-out areas in the study area were analyzed by collecting the previous survey data.Secondly,the physical properties of the selected phosphorus tailings and fly ash were tested and theoretically analyzed.Then,selected different water-solid ratios and solid phases to test the slurry performance,and selected sodium silicate and polypropylene for optimization test.On this basis,a numerical simulation test of the filling effect of stones with different strengths was carried out.Finally,the grouting effect is verified through on-site grouting test,which provides reference and guidance for the treatment of goaf with phosphor tailings filling materials.The main results obtained by the paper are as follows:?1?Collected the previous engineering survey data of the research area,analyzed and sorted out the physical and geographical overview,stratigraphic lithology,hydrogeological conditions,geological structure,and mining conditions of the research area,and on the basis of this,the research area was partitioned;?2?Through laboratory tests on the physical and chemical properties of phosphorus tailings,the analysis shows that the Si O₂ and Al₂O₃ in the phosphorus tailings can react with the cement clinker hydration products to form hydrated calcium silicate and hydrated calcium aluminate gel materials,which provide strength for the slurry stone body.Phosphorus tailings have a larger particle size and can act as a skeleton in the slurry;The physical and chemical properties of fly ash were studied.The content of spherical vitreous Si O₂ and Al₂O₃ in the fly ash reached 76.15%,which can greatly improve the fluidity of the slurry and have a positive effect on the strength of the slurry;?3?The laboratory test results of the slurry with different water-solid ratio and solid ratio are analyzed,and it is found that the water-solid ratio is 1:1.2.In the slurry containing tailings,the performance of the slurry with the solid ratio of 3:5:2 is optimal.Under this condition,the water release rate is 29.82%,the slump expansion is 162cm,the initial setting time is 1060min,the final setting time is 1220min,the stone rate is 65.19%,14d unconfined compressive strength 0.71MPa,28d unconfined compressive strength 0.92MPa?4?In the case of water-solid ratio of 1:1.2,the experiment of adding polyacrylamide to the slurry of each solid phase was carried out.It was found that when the addition amount of polyacrylamide was 0.15%,the water ratio of the selected ratio slurry was reduced to within 5%,but the strength of the cement at this time was too low to meet the strength requirements of grouting reinforcement.?5?Experiments were carried out on the three solid phase slurry with water-solid ratio of 1:1.2 by adding 1%,2%and 3%water glass solution.The study shows that when the content of water glass is 2%,the slurry in the slurry containing tailings has the best performance of 3:5:2,Water drainage rate is 17.40%,slump is 28.5cm,slump expansion is 142cm,initial setting time is 845min,final setting time is 935min,stone rate is 80.04%,14d unconfined compressive strength is 0.58MPa,and 28d unconfined compressive strength is 0.83MPa.?6?According to the geological environment conditions in the study area,an engineering geological model is established to study the influence of the different strength calculi on the vertical stress of the pillar and the distribution of the plastic zone after filling the deep goaf with numerical simulation.It is determined that the deep goaf in the study area uses a water-solid ratio of 1:1.2,a solid-to-solid ratio of 3:5:2,and a water glass content of 2%slurry for filling treatment.?7?On-site grouting test was carried out in the mined-out area,and no pipe blockage occurred during the grouting process,which verified the pu MPable type of the phosphor tailings filling material.The uniaxial unconfined compressive strength test was carried out on the stones taken out by drilling,and the results met the requirements of filling treatment.The paper has 46 diagrams,24 tables and 70 references.