Experimental Research On Properties Of Tailings Filling Material Based On Alkali Activated Slag

With the reduction of ore mining boundary grade and development of technology of grinding and beneficiation,the fineness of tailings is decreasing and the content of fine particles is increasing.Fine-tailings has small particle size,large specific surface area and strong interaction between particles,which leads to dense dewatering and large conveying resistance.Therefore,fine tailings filled of slurry tends to have low concentration and high water content.However,the traditional ordinary Portland cement(OPC)has poor curing ability due to poor water binding capacity,resulting in slow curing speed,low early strength and poor applicability,which greatly hinders the application of fine tailings cementation filling.At the same time,due to the high price of opc,the cost of using it alone is high.In addition,the production of opc not only consumes a large amount of natural resources and energy,but also releases a large amount of greenhouse gases to pollute the environment.As a new type of low-carbon gelling material,had received extensive attention in the construction industry.Compared with opc,Alkaliactivated Slag has excellent performances such as low energy consumption,fast hardness,high fluidity,strong corrosion resistance and low hydration heat.It has great application potential in fine tailings cement filling.In view of this,this paper uses slag as raw material,sodium silicate/sodium hydroxide mixture as activator.We had combined macroscopic and microscopic tests to study fluidity and setting time of slurry,mechanical strength and sulfate resistance.A series of studies were carried out and the main results were as follows:(1)Through the spread and uniaxial compressive strength test,the influence of solid concentration,binder content,activator/slag,sodium silicate/sodium hydroxide,curing conditions(temperature,humidity)and curing time were obtained,which effected flow and strength of the alkali-activated slag filling material.Using electron microscope scanning and electrokinetic potential reveals the mechanism of action of different factors from the micro level.(2)The orthogonal test method was used to study the influence for the early(3d)and medium(28d)strength of the AAS-CPB under the slag fineness,the amount of activator and sodium silicate/sodium hydroxide ratio,revealing the sensitivity of different influencing factors to strength.After overall consideration of strength and cost indicators,preferably choosed proportioning parameters with early-strength and common-type alkali-activated slag.(3)The initial/final setting time,rheological test,uniaxial compressive strength and deformation evolution characteristics of filling materials were studied under different sulfate concentrations(0,5000,15000 and 25000 ppm)and different types of cementing materials.The analysis shows the variation of internal hydration and erosion product types and quantity in the filling body,revealing the mechanism of alkali-activated slag material against sulfate attack..