Preparation Of Foamed Ceramics From Granite Scrap And Regulation Of Pore Structure

Granite scrap is the cutting waste generated during the processing of granite stone,causing serious issues such as the occupation of arable land as well as water and soil pollution.The key to resolving the environmental caused by granite scrap is to maximize its value-added utilization.In this project,granite scrap was used as the basic raw material to prepare foamed ceramics,expanding the way for the resource utilization of granite scrap and the development of foamed ceramic,as well as contributing to the goal of"double carbon".Current research on the use of solid waste to prepare foamed ceramics has made significant progress,but due to the complex chemical components of solid waste materials,there are still the problems of low solid waste utilization and nouniform pore structure.Focusing on these issues,this study systematically investigates the influence of chemical components of raw materials,foaming agents,and sintering systems on the pore structure of foamed ceramics,reveals the principle of regulation of the pore structure of foamed ceramics,and guides the optimisation of the pore structure of foamed ceramics to improve its physical properties;And guides the selection of solid waste raw materials as fluxes for the preparation of foamed ceramics in collaboration with granite scrap according to the influence of the chemical composition of blanks on the pore structure and properties of foamed ceramics,improving the utilization rate of solid waste.The main conclusions are as follows:（1）The influence of the main component and the flux component on the pore structure and properties of foamed ceramics was investigated.The experimental results show that SiO₂and Al₂O₃ form the framework of foamed ceramic.When the SiO₂ content was higher than 68wt%,the prepared samples had small pore size and low porosity;when the Al₂O₃ content is higher than 15 wt%,the average pore size of the samples decreases significantly.Na₂O and K₂O can enhance the foaming capacity of the blanks.The pore structure of foamed ceramics was uniform when the Na₂O was dosed at 4～6 wt%and the K₂O at 6～8wt%,but further increase of the doping amount destroyed the homogeneity of the pore structure.Ca O has the best effect on optimizing the uniformity of pore structure.With 8 wt%Ca O content,the pore shape of foamed ceramics was regular and full with uniform distribution.Mg O has little effect on the regulation of the pore structure of the foamed ceramics,and the increase in the amount of doping would promote the precipitation of magnesium olivine crystals,which is suitable for preparing foamed ceramic with small pore size.（2）The effect of sintering system on the pore structure of foamed ceramics was investigated using the univariate method.The results show that the increase in sintering temperature,holding time and heating rate all promote foaming.The optimum sintering regime for this experiment was determined to be 1130°C,a holding time of 30 min and a heating rate of 5°C/min.（3）The influence of the oxidation foaming agent SiC and the decomposition foaming agent MnO₂ on the pore structure and properties of foamed ceramics was studied.The results show that the pore size of foamed ceramics increases with the increase of foaming agent doping.The optimum doping of SiC in this experiment was 1 wt%and the optimum doping of MnO₂ was 1 wt%.The in situ pore formation process of foamed ceramics was discussed,revealing that the mechanism of Ca O regulation on the pore structure.The appropriate amount of Ca O can regulate the balance between the driving force of pore growth and the surface tension of the liquid phase,and also promote the precipitation of wollastonite crystals to play the role of stabiliser,thus forming a closed pore structure with full shape and uniform structure.（4）Based on the influence of flux components on the pore structure and properties of foamed ceramics,red mud,marble scrap and waste glass powder were used as fluxes to prepare foamed ceramics in collaboration with granite scrap,achieving a solid waste utilization rate of over 95%.