Study On Preparation And Properties Of Green Filling Cementitious Materials Based On Nonferrous Smelting Slag

All along,the exploitation and utilization of mineral resources play an irreplaceable role in the sustainable development of China's economy.However,in the mining process,a large number of mined-out areas and smelting slag left behind by beneficiation seriously destroyed the ecological balance of the mining area.According to the Annual Report on Comprehensive Utilization of Resources in China,at present,production of smelting slag in non-ferrous industry is large and the comprehensive utilization rate is low.At present,smelting slag is still mainly stored,which not only seriously damages the ecological environment,but also wastes a lot of land resources.Research on the preparation of cementitious materials for mine filling based on non-ferrous smelting slag will be an urgent need for the development of"waste control".This paper studies and develops the preparation technology of filling cementitious materials for goaf based on the smelting slag of Xinjiang Kelatongke Copper-Nickel Mine.It provides basic data for the preparation of filling materials and environmental protection by using solid waste near the goaf,and tries to improve the comprehensive utilization rate of the smelting slag resources of copper-nickel mine.The main research results are as follows:The chemical composition,composition content and mineral composition of the slag from Xinjiang Kelatongke Copper-Nickel Mine under natural gradation were studied.The main metal elements and their oxides in the slag were Fe₂O₃,CaO,Al₂O₃and MgO.The main non-metallic elements and their oxides were SiO₂.The contents of Fe₂O₃ and SiO₂ were obviously different under different gradation.The main mineral composition in the slag was iron olivine.Fayalite is an iron-bearing silicate mineral,which is consistent with the analysis of chemical composition of smelting slag.The effects of mechanical excitation and chemical excitation on the activation of smelting slag were studied.It is found that after mechanical activation,the hydrated slag specimens have a certain strength,but the strength is very low.Further chemical activation is needed to meet the strength requirements of cementitious materials for filling goaf in mines.Through the selection of four different chemical activators,sodium sulfate was selected as the best activator.After compound excitation with gypsum and considering the economic benefits,the original smelting slag was mixed into the cementitious material,and the compressive strength of the gellable composite material was 33.6 MPa,which met the national standards requirements of gellable composite materials.The comprehensive utilization ratio of smelting slag of copper and nickel deposits in the gellable composite material reached 85%.It provides a good basis for mass utilization of non-ferrous smelting slag in China.The addition of sodium sulfate provides the necessary chemical environment for slurry,thus providing conditions for the dispersion,dissolution and hydration of smelting slags of copper and nickel deposits.The synergistic action of gypsum and sodium sulfate promotes the activation of slag activity,which results in hydration reaction of filling body and further strength formation.The dissolution behavior of smelting slags of copper and nickel deposits and gellable composite materials to heavy metals Cu²⁺,Ni²⁺at different pH was studied.With the increase of pH,the dissolution of heavy metals from smelting slag and cementitious materials decreased accordingly.After pH>2,the dissolution rate of cementitious materials to heavy metals was lower,indicating that the prepared cementitious materials had certain solidification effect on heavy metals and were beneficial to control their dissolution.It can pollute groundwater.