| Large-scale solid wastes of metallurgy,ceramics,mining,chemical industry and other key industries have large varieties,large quantities,and heavy environmental pollution.It is very urgent to study the preparation technology of high-value mineral materials using related solid wastes.Aiming at the current situation of domestic waste electric porcelain widely used in landfilling,paving and other low-value decremental digestion utilization,as well as the outstanding problems of decreased refractory mineral raw material,high mining cost and heavy environmental pollution,the potential of high value utilization of waste electric porcelain was fully explored based on the characteristics of waste electric porcelain,such as block,graining,compactness,hardness and high temperature resistance.The preparation of high temperature resistant materials applied at around 1100-1300 °C using waste electrical porcelain as the main raw materials and the solution to the problem of harmful effect of high temperature liquid on the high temperature performance of waste electric porcelain were studied in this dissertation,which has positive significance to expand the way of high-value large-scale utilization of waste electric porcelain and save the resources of refractory raw materials.The main results of the dissertation are as follows:(1)Based on the characterization and analysis of raw materials for waste electric porcelain,the phase optimization of the components in the waste electric porcelain glaze at high temperature and the shielding effect of harmful components were studied.The results showed that the microstructure of the waste electric porcelain body was basically stable at 1250 °C.The component design of the pigment and glaze coating,as well as the new high temperature resistant phase generated during the reaction in the contact layer area between the liquid components of the pigment and glaze at high temperature and the coating were studied.It was found that the new phase had a better high temperature resistance,which had a good "shielding" effect on the harmful components in the color glaze,and weakened the effect of its deterioration high temperature performance.The total amount of waste electrical porcelain preparation research showed that when the ratio of coarse particles: medium particles: fine powder is 35:30:35,the comprehensive performance of the sample was the best after heat treatment at 1200 °C for 3 h,whose flexural strength and compressive strength were 33.2 MPa and 89.48 MPa,respectively.(2)The effects of adding alumina and bauxite clinker on the properties of high temperature resistant materials made from waste electric porcelain were studied.The results showed that the flexural strength and compressive strength at room temperature of the specimens with 20 % aluminum ash were 25.31 MPa and 67.48 MPa respectively,which were 59 % and 40 % higher than that of the samples prepared entirely by of waste electrical porcelain.The flexural strength and compressive strength of the samples with 25 % bauxite clinker powder were 28.15 MPa and 81.41 MPa respectively,which were 77 % and 69 % higher than that of the samples prepared entirely by of waste electrical porcelain.The analysis showed that the mullite fiber generated in-situ in the samples after adding the appropriate amount of aluminum ash produced a fiber bridging effect,which could increase the path of crack propagation inside the samples and synergistically toughened to improve the mechanical strength of the samples;the appropriate amount of bauxite clinker powder could promote the formation of mullite crystals in the high-temperature liquid phase reaction and kept the high temperature shape stability of the samples.(3)The synergistic contribution mechanism of different binders and silica sol to the strength of samples at different temperatures was studied.The results showed that the strength of silica sol binder at medium and low temperature mainly depended on the cementation of-Si-O-Si–.After adding aluminum dihydrogen phosphate,aluminum metaphosphate and its polymer would be formed at medium temperature,which could improve the medium temperature strength of the sample.Silica sol binder added with metakaolin could promote the formation of mullite and spinel crystal nuclei in the sample,which was beneficial to increase its high temperature strength.The dependence of the flexural strength on heat treatment temperature at different temperature regions of the waste electrical porcelain-based non-sintered materials prepared by metakaolin/silica sol was obtained,and the mechanism of enhanced thermal shock stability was revealed. |
PDF Full Text Request