Study On Preparation Of Based Geopolymer Of The High Alkali Coal Ash Slag

The liquid slagging technology has the advantages of high thermal efficiency,high gasification strength,and convenient sewage treatment.It has been widely used in the coal chemical industry and can be used as the main combustion and slagging process for high-alkali coal.With the over-exploitation of high-quality coal resources and the popularization of liquid slagging technology,a large amount of high-alkali coal ash slag will be produced.Therefore,there is an urgent need to carry out research on the resource utilization of high-alkali coal ash.As a new type of cementing material,geopolymer has significant advantages in the utilization of solid waste resources.Research have shown that fly ash and coal gangue,which are the same as high-alkali coal ash slag,are solid wastes of the coal industry.As a raw material for the preparation of geopolymers.Therefore,this paper aims at the utilization of high-alkali coal slag resources.Based on the principle of geopolymer preparation and characteristics of high-alkali coal ash,this paper develops the preparation process,curing method and resistance of high-alkali coal ash-based geopolymers.High temperature research.The main research contents are as follows:(1)The chemical composition,physical properties,reaction activity and other physical and chemical properties of high-alkali coal ash slag were analyzed,and fly ash was used as a control to comprehensively evaluate the alkali excitation activity of high-alkali coal ash slag.Results show that the properties of high-alkali coal ash slag and fly ash are similar,they are typical low-calcium raw materials,and the alkali leaching rate of SiO2 and Al2O3 is small,so the strength of geopolymer prepared from pure high-alkali coal ash slag is low,then through mixing mineral powder can achieve the purpose of " increase calcium content to increase strength".(2)The effects of high alkali coal ash residue content,water-cement ratio,water glass modulus,and alkali activator content on the properties of high alkali coal ash residue-based geopolymers were investigated through a single factor test method.Based on this,the decisive order of the four factors on the performance of high-alkali coal slag-based geopolymer was further determined by the orthogonal test method,and the optimal values of the four test factors were determined.Results show that the four factors that influence the performance of the preparation of geopolymers from high-alkali coal ash slag are as follows: the amount of high-alkali ash slag > water-cement ratio > water glass modulus > the amount of alkali activator;The optimal blending ratio of high-alkali coal slag base polymer is: 30% of high-alkali coal slag,0.31 of water-cement ratio,2.0M of water glass modulus,5% of alkali excitation,and 28 d compressive strength of optimal mixing ratio reaches 85 MPa.(3)Adjust the water-cement ratio on the basis of the optimal ratio to make the experimental group and the blank control group correspond to the consistency of the standard consistency.Processing method.Results show that the optimal curing system for high-alkali coal slag-based geopolymers is steam curing,and the 28 d compressive strength is 70.45 MPa.Increasing the grinding time of high-alkali coal ash slag is beneficial to increase the early compressive strength of high-alkali coal ash-based geopolymers;Adding silica fume and calcined kaolin can improve 28 d compressive strength of high-alkali coal ash slag-based geopolymer;When high-alkali coal ash slag is calcined at 800 ?,and high-alkali ash slag-based geopolymer 1d compressive strength can reach to 31.2 MPa.After calcining at 1200 ?,the high-alkali coal ash slag-based geopolymer has the highest 28 d compressive strength,which is 90.59 MPa.(4)By means of TG-DSC,XRD,FT-IR,etc.,the composition,structure and performance of high alkali coal ash slag-based geopolymers were studied under high temperature conditions,and the mechanism of high alkali coal ash slag on its high temperature resistance was clarified.The research results show that the high alkali coal ash slag contains spinel,which has a high crystal transition temperature and stable high temperature performance,so it can improve the high temperature resistance of geopolymers.