Study Of The Thermal Storage Ceramic From Graphite Tailings

Concentrating Solar Power?CSP?technology,as an advanced technology of solar thermal utilization,can effectively convert solar energy into light and heat to meet the needs of human energy consumption.Graphite tailings as a sort of industrial solid castoff,is formed by graphite mineral resources mining after discharged tailings pulp by natural air dry dehydration.Usually the disposal method of Graphite tailings has thrown placed around the mine tailings or discharge in the rivers so that it was of the pollution to the surrounding environment.In view of the development and utilization of solar energy has an immeasurable prospect and benefit,the graphite tailings need to be used as early as possible.Use the graphite gangue,shale,kaolin,potash feldspar,sodium feldspar,talc,silicon carbide as raw material,with buried powder sintering prepared graphite tail mineral ceramic with high heat conductivity.The effect of sintering temperature,composition of formula,mineralization agent and inorganic materials with high thermal conductivity on the structure and properties of graphite tailings thermal storage ceramics by using XRD,SEM,and other modern test technology.The effect mechanism of broadening the sintering temperature and improving the thermal conductivity of graphite tailings was studied.To designed series A with the main raw material of graphite tailings,shale,kaolin.Samples of A series were fired at temperature 1060¹140?by the semi-dry pressing and pressureless sintering.The effects of composition and firing temperature on the physical and chemical properties and thermal shock resistance of series A samples were discussed.Both the samples of A1 formula?graphite tailings50%,shale20%,kaolin 15%,potassium feldspar 10%,albite 5%?samples and A3 formula?graphite tailings70%,shale10%,kaolin 5%,potassium feldspar 10%,albite 5%?were fired at 1100?are excellent performance.The water absorption,porosity,bulk density and bending strength of A1 samples fired at 1100 C were 0.19%,0.46%,2.44g/cm³ and 82.75 MPa,respectively.The bending strength is 81.60 MPa and the bending strength loss rate is 6.79%after 30 times of thermal shock cycles?RT⁶00??.Sample A1 main crystal phase of sodium feldspar,albite honeycomb form the skeleton structure of the samples,the plate shaped alpha quartz and granular hematite diffusion within the sample through the glass phase bonded into solid microstructure.The water absorption,porosity,bulk density and bending strength of A3 samples fired at 1100?were 0.07%,0.17%,2.48 g/cm³,79.06 MPa.The bending strength is 76.90 MPa and the bending strength loss rate is 3.90%after 30times of thermal shock cycles?RT⁶00??.The A3 sample is mainly composed of a honeycomb plate labradorite,alpha quartz and hematite particles.The firing temperature range of A1,A3 formula samples is 1080¹030?,firing temperature range is litter narrow.Mineralizers are added to broaden the range of the firing temperature of graphite tailings ceramic at the basic formula of A1,A3 and the mechanism is discussed.Two kinds of mineralizers?talc and potassium feldspar?were introduced respectively at the basis of A1 to design G series samples.Sample G4?A1 samples with added 20%talc?which fired at 1110?had optimal properties with water absorption,porosity,bulk density and bending strength of 0.19%,0.22%,2.45 g/cm³ and 14.38 MPa,respectively.After 30 thermal shock cycles?RT⁶00°C?,the bending strength of sample G4was 91.50 MPa and strength loss rate was 13.44%.The main phases of the sample G4 fired at 1110?were calcium feldspar with honeycomb structure,enstatite with long cylindrical,grain crystal and plate-like quartz crystals.Two kinds of mineralizers?talc and potassium feldspar?were introduced respectively at the basis of A3 to design H series samples.Sample H3?A3 samples with added 15%talc?which fired at 1110?had optimal properties with water absorption,porosity,bulk density and bending strength of 0.27%,0.11%,2.53g/cm³and 124.45 MPa,respectively.The phases of the sample H3 were calcium feldspar with honeycomb structure,enstatite with long cylindrical,grain crystal and plate-like quartz crystals.After 30 thermal shock cycles?RT⁶00°C?,the bending strength of sample H3 was113.30 MPa and strength loss rate was 9.17%.The firing temperature range is1080¹140?both G series samples and H series samples.Results showed that introduce of talc and potassium feldspar can broaden the firing temperature range and improve the structure and performance of graphite tailings ceramics.Two kinds of inorganic materials with high heat conductivity?SiC and Si₃N₄?were added to the basis of H3 with different amount to design series K samples.The samples series K were prepared by semi-dry pressing and powder embedded sintering.Thermal conductivity mechanism of graphite tailings ceramic added inorganic materials with high heat conductivity was discussed.Samples of K series were fired at temperature 1110¹210?and mechanical properties,thermal shock resistance of sampless were investigated.Results demonstrate that Sample K3?H3 samples with added 30%SiC?which fired at 1170?had high degree of densification,good thermal shock resistance and significantly higher thermal conductivity than H3samples.Its water absorption,porosity,bulk density,bending strength is0.04%,0.06%,2.69 g/cm³ and the bending strength of 142 MPa.XRD and SEM micrographs revealed that a large number of anorthite crystal honeycomb form the framework structure of the sample,massive quartz crystal,Si C bulk crystals and short column shaped mullite crystals diffusion in the framework structure connected firmly through glass phase.After 30 thermal shock cycles?RT⁶00°C?,there were not any cracks formed in the sample and the bending strength of sample K3 was 138MPa,decreased by 22.41%,indicated that it had favourable thermal shock resistance.The results showed that sample K3 fired at 1170?is a kind of graphite tailings ceramic using as heat storage materials with high heat conductivity.Thermal conductivity rate of H3 sample fired at 1110?was 1.91 W/?m·K?under 600?,thermal conductivity rate of K3 samples fired at 1170?was 3.89 W/?m·K?under600??The graphite mineral ceramic added SiC materials can significantly improve the thermal conductivity.The results showed that K3 sample fired at 1170?is a kind of high heat conductive graphite tail mineral material.K3 formula samples clinker powder fired at 1170?,high temperature binder KNO₃,flux,boron anhydride as raw material used in preparation of package agent for inorganic salt-Graphite tail matter thermal storage ceramic composite heat storage material,analysis of Influence of composition on the binding properties of the composition of the packaging agent to the matrix.After the combination of the package and the ceramic substrate,the sample is treated by 600?,The F1 package agent?70%K3 formula samples clinker powder,30%KNO₃,10%flux?,even though Combined sample with 30 times thermal shock cycling,No cracks on the surface of the package agent layer.The microscopic structure of F1 package agent in conjunction with substrate samples analysis package agent layer exists more breath hole and loose structure,packaging agent by combining the layer penetration into the matrix and had good adhesion to the substrate matrix layer has dense microstructure.Preparation of high heat conductive graphite tail mineral honeycomb ceramic body by the practice of the mud and the stale and the vertical extrusion technology K3 formula as the main raw material add plastic agent to preparation of high heat conductive graphite tail mineral honeycomb ceramic body by the practice of the mud and the stale and the vertical extrusion technology with discussed the influence of firing temperature on graphite tail mineral honeycomb ceramics physicochemical properties,phase composition and microstructure.Optimization of physical properties of Graphite tail mineral honeycomb ceramics with high thermal conductivity and high heat conductivity at 1190?,the water absorption rate,porosity,bulk density respectively 2.98%and 7.56%,2.73g.cm^-3.The main phase of honeycomb ceramics are calcium feldspar,quartz and pyroxene.The microstructure of ceramic honeycomb samples analysis of crystal surface phase showed that various crystal phases is connected as the main structure through the glass,a hexagonal silicon carbide crystal cross inserted into growth in the surface of the main structure.In order to analyze Three chloride PCM which prepared by the pure chloride of barium chloride,potassium chloride,sodium chloride?28%:37%:35%?with the TG-DSC analysis.Research results show that three chloride PCM phase change temperature is 543?,latent heat of phase change is 172.53J/g.Within the temperature range of room temperature to 700?,Three chloride PCM occurs by solid opposite molten into liquid phase transition of the physical changes,no decomposition reaction so that it can be used as the sun in the temperature section of the latent heat storage material.The three chloride PCM is encapsulated in the heat guide graphite tail mineral honeycomb ceramic by using F1 package agent,which called sensible heat composite heat storage material,composite heat storage materialstreated at 600?,three chloride PCM is leaking from the package agent,and honeycomb ceramic matrix without penetration phenomenon,then contact area with less.