Research And Application Of Alkali-aluminum-silica Tailings Foam Ceramic Materials

According to the current problems of wall thermal insulation materials and high value-added use of tailings,this paper used a powder body high temperature of melt-foaming process to prepare a kind of environmentally friendly foamed ceramic thermal insulation board with a high content of 80wt% of tailings and waste red mud which also had good durability,light weight and high strength,based on the study of the chemical composition of tailings and auxiliary materials,X-ray diffraction analysis and TG-DSC thermal analysis.An orthogonal test was designed to study the main chemical composition of the blank.The influence of foaming agent dosage,grinding time and firing process on the properties of foamed ceramics;single factor test was designed to study the relationship between the specific chemical composition and the properties of foamed ceramics.Through the orthogonal test of 7 factors and 3 levels of the amount of tailings,amount of red mud,amount of albite,amount of blowing agent,grinding time,firing temperature and firing time,the best composition formula of foamed ceramic and the most excellent process conditions,the results show that the firing temperature has the greatest impact on the apparent density and compressive strength of foamed ceramics.When the firing temperature is 1220°C,the apparent density of the foamed ceramic is 536kg/m3 optimally;when the firing temperature temperature is 1180°C,the compressive strength of the foamed ceramic is4.5Mpa optimally;when the sintering temperature is 1220°C,the porosity of the foamed ceramic is optimally 75%;when the amount of the sodium feldspar is 20wt%,the water absorption rate of the foamed ceramic is the best which is 1.4%.The final composition of the foamed ceramic was determined to be 55 wt% of tailings,25 wt% of red mud,20 wt% of albite,5 wt% of dolomite,and 0.3 wt% of foaming agent.The best process is grinding time15 min,firing temperature 1200°C,holding time 60 min.The experimental foam ceramic sample was prepared in accordance with the optimum process flow.The final apparent density was 605 kg/m3,the compressive strength was 5.3 MPa,the porosity was 72.7%,and the water absorption was 1.4%.The effect of various chemical composition changes on the properties of foamed ceramics was analyzed using the single-factor variable method.The results showed that: Si O2 has the effect of increasing the firing temperature and increasing the apparent density.When the Si O2 content reaches 8wt%,foaming occurs.The apparent density of the ceramic was 710kg/m3,and the compressive strength was 5.4MPa;Al2O3 will significantly increase the temperature of the liquid phase generated by the foamed ceramic,increase the viscosity and surface tension of the liquid phase,and can stabilize the pore structure and increase thecompression resistance.When the content of Al2O3 reaches 8wt%,the apparent density of the foamed ceramic is 992kg/m3,and the compressive strength is 24.1Mpa.The Ca O has a fluxing effect,which can reduce the firing temperature and reduce the viscosity and surface tension of the liquid phase,but the amount too much will adversely affect the compressive strength.When the content of Ca O is 8wt%,the apparent density of the foamed ceramic is350kg/m3,and the compressive strength is 5.1Mpa;Mg O can reduce the firing temperature and liquidus viscosity.Under the circumstances,the surface tension of the liquid phase can be increased to stabilize the foam.When the Mg O content reaches 8 wt%,the apparent density of the foamed ceramic is 500 kg/m3,the compressive strength is 4.5MPa;K2CO3 and Na2CO3 are both It will generate its corresponding oxides at high temperature,and it is a strong fluxing agent,which can greatly reduce the firing temperature of foamed ceramics and reduce the viscosity and surface tension of liquid phase.The appropriate amount of Fe2O3 can be added at low temperature liquid phase surface tension and viscosity.When it is high,it promotes the oxidation reaction of the foaming agent and has a stabilizing effect.Too much addition will lead to the occurrence of partial melting holes and damage the pore structure of the foamed ceramic.When the Fe2O3 content reaches 4wt%,the apparent density of the foamed ceramic is 880kg/m3,and the compressive strength is 8.4Mpa.The influence of the fineness of the blowing agent and the content of the tailings on the performance of the foamed ceramics was explored.The final determination of the fineness of the blowing agent was 200 mesh,and the amount of tailings was finally determined to be 55 wt%.