Firing Foaming Mechanism Of Polishing Porcelain Stoneware Tile Residues And Its Materials Preparation Application

Polishing porcelain stoneware tile residues（PPR）is a kind of solid waste produced by cutting,grinding and polishing in ceramic production.Because the PPR contains SiC（from abrasive）and other impurities,when it is used as ceramic raw material for resource utilization,it will cause ceramic bodies foaming and deformation during firing.Its direct resource utilization has long been the most critical technical problem for the ceramic industry to achieve zero emission production of solid waste.Usually the SiC surface has a layer of SiO₂ protective film.It will be corroded by the surrounding silicate liquid at high temperature,causing the SiC to come into contact with oxygen and be oxidized to produce gas foaming.However,there is no in-depth and systematic study on the foaming mechanism of PPR.Therefore,in this thesis,the firing foaming mechanism of PPR,foaming control and its application in material preparation are studied in detail,in order to provide theoretical basis and practical way for the direct resource utilization of PPR,which is of great significance.Due to the unstable chemical composition of the PPR,this thesis thoroughly and systematically studies the PPR through the composite simulation of the main chemical components of the PPR,SiO₂,Al₂O₃,MgO,Na₂SiO₃ and SiC.Using SiO₂,Al₂O₃,MgO and Na₂SiO₃ as the raw materials of the first layer,SiO₂ as the raw materials of second layer and SiC as the raw materials of the third layer,a three-layer structure sample is constructed and then fired at 1200℃under different corrosion times.The corrosion effect of silicate liquid on SiO₂protective coating of SiC surface during sintering of PPR was studied in detail by interfacial corrosion between three layers of samples.The results show that the corrosion rate of SiC in silicate liquid changes dynamically in a certain range,and the thickness of corrosion layer between SiO₂ and silicate liquid presents periodic law of waveform change.On this basis,SiO₂,Al₂O₃,MgO,Na₂SiO₃and SiC were used as raw materials,supplemented by carbon powder,aluminum powder and silicon powder,and fired at1100～1200℃by dry pressing.The effect of the gas produced by the sintering of SiC in the PPR on its foaming was deeply studied.The results show that the foaming is not obvious when PPR is fired at low temperature,the path of oxygen diffusing into silicate liquid is long,the oxygen on SiC surface in PPR is less,SiC can only generate CO by incomplete oxygen reaction,and the amount of CO gas is less,which is difficult to cause foaming of PPR.The foaming phenomenon of PPR is obvious when it is fired at high temperature,because a large amount of CO₂ gas is produced to cause violent foaming of the PPR.Secondly,SiO₂,Al₂O₃,MgO,Na₂SiO₃and SiC were used as raw materials,changing the ratio of SiO₂ and Al₂O₃,and fired at 1200℃,and then the foamed ceramics were prepared.The effects of oxide components and content of PPR on its properties were quantitatively studied.The results show that when the SiO₂ content in PPR is controlled at about 10 wt.%,a kind of high-strength and thermal insulation foamed ceramics with compressive strength of 30.6 MPa and thermal conductivity of 0.43 W*m^-1K^-1 can be obtained.Furthermore,SiO₂,Al₂O₃,MgO,Na₂SiO₃ and SiC are used as raw materials to simulate PPR,and aluminum powder was introduced into it.After firing at 1200℃,the influence of aluminum powder on the properties of PPR was quantitatively studied.The results show that the introduction of 5 wt.%aluminum powder into PPR can completely inhibit its foaming during firing,and a kind of high-strength building material with flexural strength of 48.0±3.8MPa and compressive strength of 180.5±3.5 MPa was obtained.Finally,two kinds of porous ceramics are prepared from spray granulation powder and PPR of ceramic factory by gel-casting at 1060℃.The effects of spray granulation powder and PPR on the sound absorption properties of porous ceramics are studied respectively.The results show that the porous ceramic with connected pore structure prepared by PPR has good sound absorption effect on the noise in the range of 200～2000 Hz,and the average sound absorption coefficient is about 0.3.