Phosphogypsum-slag Experimental Study Based New Gelling Material In The Second Area Of Jinchuan Mine

As a precious metal mine in China, Jinchuan mine has always been mined by usingthe method of a hierarchical approach to backfill mining. Mine with high cost of fillingmainly use the river sand as filling aggregate and use cement as gelling material every year.Thereby, with the deep mining, it’s corresponding to violent activities in deep pressure andthe pressure of mining sites increased. The requirement of filler strength becomes higherand higher (the strength of3days larger than1.5MPa, the strength of7days larger than2.5MPa, the strength of28days larger than4MPa). In order to ensure mine safety underthe premise of reducing the cost of filling, it is critical necessary to develop low-cost andhigh-strength new filling material. Development of new gelling materials not only reducescosts, but also can achieve resource utilization of solid waste, and then to realize the eco-mining.The Corporarion of WengFu in Gansu province, discharged a large number ofphosphorus gypsum waste in the process of production of phosphate fertilizer each year, isadjacent to Jinchuan mine. The phosphorus gypsum, as a kind of solid waste, dealt withaccumulation. It occupies a large amount of land and cost maintenance each year, andleads to dust pollution as well. Therefore, utilization of phosphorus gypsum is not onlyrelated to the phosphate fertilizer industry and society, but also the harmony betweenenvironment and sustainable development.In this paper, using river sand as a filler aggregate, phosphogypsum, slag powder andcomplex stimulator were choosen to develop phosphorus gypsum–slag based gellingmaterial, instead of the high price of cement in Jinchuan Mining.The experiment adopted orthogonal design with plastic sand ratio of1:4and slurryconcentration of78%. Firstly, according to the nearby principle, slag powder of Baotousteel was used to test, but the activity of slag powder can not satisfy the requirement of thesamples’ strength. Then active slag powder from the Tangshan steel, which was higher than Baotou steel slag, was used to test and obtain the original results. By means of XRDmethod to study the microstructure of gelling material deeply, it was verified that filler ofphosphogypsum-based hydration products were mainly ettringite and C-S-H gel. Throughthe experimental results using DPS data processing software for regression analysis andMatlab to establish the neural network model to optimize the decision, it could be obtainedthe influence of content of quick lime, phosphogypsum, sodium hydroxide and glauber’ssalt on curve of the strength of filling body and the phosphogypsum-based programs earlystrength gelling material filling, and then acquired the optimal plan of ratio. Undercondition of the optimal mixture ratio, phosphorus gypsum cementing filling material ofthe3d,7d and28d filling body uniaxial compressive strength were1.532MPa,3.099MPaand4.157MPa separately. All of that could satisfy the demand of strength in jinchuanmine.Lastly, the cost of new cementing material is far less than the cost of the cementthrough a market survey of the price with various factors. Thus, it is completely feasible tomine by using the new phosphorus gypsum–slag based gelling material to replace cementin jinchuan mining with filling method.