Preparation Of Foamed Ceramics From Silicate Industrial Waste(Tailings) Ore

Foamed ceramic is a kind of light thermal insulation material,which is made by adding some foamed agent and cosolvent to ceramic material through high temperature sintering,and is widely used in wall,roof and underground engineering materials.In this paper,the effects of foamed agent content,glass phase content,chemical composition and mineral content,and holding time on microstructure and properties of foamed ceramics were studied by using industrial waste（tail）ore as raw material.It provides a theoretical basis for the subsequent successful preparation of foamed ceramics from tailings.First of all,chemical reagents were used as raw materials in this study at the adding amount of foaming agent was 0.34wt%and sintering temperature was 1250℃to prepare foamed ceramics.The influence of the content of various chemical reagents on the structure and performance of foaming ceramics was analyzed.The results show that in the composition system of the Na₂O-Al₂O₃-SiO₂,the more the content of Na₂O,the higher the content of the glass phase in the ceramic,the lower the viscosity of glass phase,cause ceramic aperture increases,density is lower,so the minimum thermal conductivity is 0.09 W/（m·K）,porosity of 81.08%in the preparation of foamed ceramics.In the composition system of the Na₂O-Al₂O₃-SiO₂,as the content of Al₂O₃increases,the content and the viscosity of the glass phase increases,the pressure on the bubble hole increases,and the pore size of foamed ceramics decreases and the density increases.Then,in the composition system of the Na₂O-Al₂O₃-SiO₂,when the adding amount of foaming agent was 0.33wt%and sintering temperature was 1250℃,Fe₂O₃was introduced as a flux,which decomposed to generate oxygen at high temperature,as the content of Fe₂O₃ increases,the viscosity of glass phase decreases,resulting in the phenomenon of bubble hole wall annexation,and the bubble hole of foamed ceramics was too large.So the amount of Fe₂O₃ should not be too much,with less than 1.5wt%as appropriate.Finally,feldspar and sodium carbonate are used as raw materials in this study to prepare foamed ceramics.When the sintering temperature is 1250℃,the influence of the content of feldspar on the structure and properties of the foamed ceramics are explored.The results show that when feldspar and sodium carbonate were introduced into Na₂O at the same time,and the content of foaming agent was 0.33wt%,the larger the content of feldspar,the smaller the pore size and the higher the density of foamed ceramics.When preparing foamed ceramics with feldspar as raw material,the pore size of ceramics increases gradually with the increase of the content of foaming agent.However,when the content of foaming agent is too much,the pore size reaches the extreme value,so the content of foaming agent should be less than 1.25wt%.The porosity and thermal conductivity of foamed ceramics prepared with feldspar reached73.13%and 0.13 W/（m·K）.Feldspar,shale and quartz are used as the main raw materials to prepare foamed ceramics,orthogonal experiment was used to explore the influence of holding time,content of various raw materials,content of foamed agent and sintering temperature on density,thermal conductivity,pore diameter and glass phase content of foamed ceramics.Orthogonal test shows that the degree of influence of various factors on the density and thermal conductivity of foamed ceramics is in the following order:foaming agent content>sintering temperature>holding time>raw material content;the degree of influence of various factors on pore diameter and the content of ceramic glass phase is in the following order:sintering temperature>holding time>foaming agent content>raw material content.