| Red mud is the solid waste residual when alumina is produced using bauxite.As the big alumina producing country, Chinese red mud output is more than one third of global output and that brings forth huge environmental pollution and potential safety problems.At the same time,as the big steel producing country,iron tailings produced through steel-making have also become the important pollution source,according to incompletely statistics,the cumulative stockpiled iron tailings come up to2x109t in china. Following with Chinese economy developing fast,the demands for energy is increasing more and more,but more than70percents of energy are provided by coal. As the limited coal consumed continuously, searching for new energy succedaneum becomes the important point to every countries, so the clean and unlimited solar energy becomes the focus of world attentions. In order to develop red mud and iron tailing environmentally friendly and taking the intense energy shortage situation into consideration, in this study solar energy thermal storage materials are made in the raw materials of red mud and iron tailing.In this paper, at first Shandong bayer red mud, Shandong shale, Shandong talc, Shandong potassium feldspar, Linzhou albite, Shandong quartz were used as the main raw materials, prepared the K-Al-Si system solar energy thermal storage ceramic materials. Using XRD (X-ray diffraction), SEM (scanning electron microscope) and other modern analysis techniques tested the microstructure and properties of P series. The results indicate that it is possible to use red mud as main raw material to produce the solar energy thermal storage ceramic materials.The properties of P-4sample fired at1080℃was better, the porosity was7.82%, the water absorption was3.07%, the bulk density was2.55g·cm-3, the bending strength was46.66MPa, the sample wasn’t cracked by thermal shock resistance (room temperature-800℃, air-cooled) after30times,and flexural strength after thermal shock was38.51MPa(the loss rate of strength was17.47%),the loss rate of quality after thermal shock was0.009%, the thermal expansion coefficient of the sample was11.24x10-6℃-1, and the heat capacity was6.9295x10-1J·(g·K)-1, the thermal conductivity coefficient was5.709x10-3cm2·s-1, the thermal conductivity was10.237x10-1W·(m·K)-1, the heat storage density was415.77kJ·kg-1. XRD analysis showed that the main phase of the corundum samples were hematite, tridimite, sillimanite and albite.In order to improve the red mud ceramic thermal storage material’s thermal shock resistance, the new G series were designed on the base of P series. Using XRD (X-ray diffraction), SEM (scanning electron microscope)and other modern analysis techniques tested the microstructure and properties of G series. The results indicated that adding the DaYe aedelforsite could improve material’s thermal shock resistance. The properties of G-4sample fired at1040℃was better, the porosity was39.17%, the water absorption was21.27%, the bulk density was1.89g·cm-3, the bending strength was33.32MPa, the sample wasn’t cracked by thermal shock resistance (room temperature-800℃, air-cooled) after30times,and flexural strength after thermal shock was32.47MPa(the loss rate of strength was2.56%), the thermal expansion coefficient of the sample was10.48x10-6℃-1which was6.76%smaller than P-4, and the heat capacity was7.4214x10-1J(g·K)-1, the thermal conductivity coefficient was4.368x10-3cm2·s-1, the thermal conductivity was7.273x10-1W·(m·K)-1,the heat storage density was445.28kJ·kg-1which was7.10%more than P-4. XRD analysis showed that the main phase of the corundum samples were hematite, tridimite, albite, anorthite and kyanite.Although G series had improved the material’s thermal shock resistance, the bending strength was decreased. On the premise of keeping original good thermal shock resistance,continue to improve the strength and thermal shock resisitance of the samples,L series were designed through adding Si3N4or SiC into P-4and G-4. Using XRD (X-ray diffraction), SEM (scanning electron microscope) and other modern analysis techniques tested the microstructure and properties of L series fired at1040℃. The results indicated that adding Si3N4could improve material’s strength and thermal shock resistance. The properties of L-1sample fired at1040℃was better, the porosity was39.62%, the water absorption was19.05%, the bulk density was1.96g·cm-3, the bending strength was41.16MPa, the sample wasn’t cracked by thermal shock resistance (400~800℃) after30times,and flexural strength after thermal shock was39.62MPa(the loss rate of strength was3.74%), the thermal expansion coefficient of the sample was10.47x10-6℃-1, and the heat capacity was5.9058x10-1J·(g·K)-1, the thermal conductivity coefficient was4.533x10-3cm2·s-1, the thermal conductivity was5.852x10-1W·(m·K)-1,the heat storage density was354.35kJ·kg-1. XRD analysis showed that the main phase of the corundum samples were hematite, tridimite, albite, anorthite, kyanite and silicon nitride.At the same time, the ceramic thermal storage material using the BenGang iron tailing as the main raw material was studied.The H series were designed using the BenGang iron tailing, Shandong shale, Shandong potassium feldspar, Linzhou albite and HeBi bauxite as the main raw materials. Using XRD (X-ray diffraction), SEM (scanning electron microscope) and other modern analysis techniques tested the microstructure and properties of H series. The results indicate that it is possible to use iron tailing as main raw material to produce the solar energy thermal storage ceramic materials.The properties of H-3sample fired at1120℃was better, the porosity was21.47%, the water absorption was10.26%, the bulk density was2.09g·cm-3, the bending strength was59.02MPa, the sample wasn’t cracked by thermal shock resistance (400~800℃) after30times.and flexural strength after thermal shock was56.78MPa(the loss rate of strength was3.79%), the thermal expansion coefficient of the sample was10.55X10-6℃-1, and the heat capacity was1.0087x10-1kJ·(kg·K)-1, the thermal conductivity coefficient was4.039x10-3cm2·s-1, the thermal conductivity was8,413x10-1W·(m·K)-1, the heat storage density was605.22kJ·kg-1. XRD analysis showed that the main phase of the corundum samples were tridymite, adamantine spar and hematite.In this research, the matrix material, as well as packing agents and PCM used for composites ceramics of potential-sensible storage materials, was studied. The optimal formulations were gained by variety experiments of different types and formulations of packing agents. The optimal formulation of red mud-based packing agents comprised of50wt%red mud,35wt%synthetic cordierite power,5wt%KNO3,10wt%Boron frit while Iron ore tailings-based packing agents comprised of80wt%Iron ore tailings and20wt%Boron frit. It is observed the packing agents and substrate combined tightly together in the optimal formulation via SEM. The sphere wrapped NaCl and MgCl2was tested by SEM and the results shows that red mud ceramic regenerator balls wrapped MgCl2have superior compatibility and properties while iron ore tailings ceramic regenerator balls wrapped NaCl have superior compatibility and properties. |
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