Preparation And Characterization Of Foamed Ceramics From Tantalum And Niobium Tailings

Foamed ceramic is a new type of porous material with many excellent properties,which is widely used in construction,environmental protection,metal casting and other fields.As solid wastes generated during mining and beneficiation,tailings not only occupy land,but also cause serious environmental pollution and ecological damage to the mine and surrounding environment.Research has found that tailings contain a large amount of silicon dioxide and aluminum oxide necessary for the preparation of foam ceramics,and are considered to be one of the ideal raw materials for the preparation of foam ceramics.However,it is unclear whether tantalum niobium tailings can produce foamed ceramics with excellent properties.Therefore,this paper selects tantalum niobium tailings as the main raw material,albite and kaolin as auxiliary raw materials,and Si C as foaming agent to prepare foaming ceramics by direct foaming method.The effects of process parameters and raw material composition on the structure and properties of foamed ceramics were investigated using single factor variable experiments,and the optimal scheme was determined using orthogonal experiments.The single factor variable experimental results show that the structure and properties of foam ceramics are significantly affected by factors such as sintering temperature,holding time,Si C content and tailings content.With the increase of sintering temperature and holding time,the effects of both on the apparent density,compressive strength,water absorption,open porosity,true porosity and pore size of sintered samples are basically the same,with only differences in closed porosity,which first increases,then decreases and increases,respectively.With the increase of Si C content,the apparent density and compressive strength of foamed ceramics first decrease and then increase,while the water absorption,true porosity,closed porosity and pore size first increase and then decrease,while the open porosity increases.The addition of tailings can increase the apparent density and compressive strength of foam ceramics,while other performance indicators decrease with the increase of tailings dosage.Further analysis shows that changes in process factors and raw material composition can change the crystal phase content of the foam ceramic sample,but cannot change its phase composition.The analysis of orthogonal experimental results shows that the influence of various factors on the performance of foam ceramic samples is different,and the optimization schemes obtained based on different properties are also different.Based on comprehensive analysis,the optimal process conditions for preparing foamed ceramics are as follows:sintering temperature is 1150℃,holding time is 40 min,Si C content is 0.5%and tailings content is 70%.The foam ceramic sample prepared by this scheme has an apparent density of0.71 g/cm³,water absorption rate of 2.83%,compressive strength of 6.94 MPa,and apparent porosity of 2.01%.Through X-ray diffraction analysis of the foam ceramic sample,it was found that the crystallization condition of the sample was good,and the main phase was composed of quartz（Si O₂）and albite（Na Al Si₃O₈）,followed by anorthite（Ca Al₂Si₂O₈）.In order to further explore the variation of various properties of sintered samples with sintering temperature and holding time,a multivariate linear regression model was used for regression analysis.The results showed that the R² of the binary linear regression models obtained for the apparent density,water absorption,compressive strength and apparent porosity of sintered samples were 0.881,0.871,0.914 and 0.960,with good fitting effects.