Effect Of Foaming Agent On Viscosity And Thermal Properties Of Foam Glass Prepared From Molybdenum Tailings

The increasing demand for energy and mineral resources in society has caused serious environmental pollution.For example,a large amount of land is occupied by the tailings after metal smelting,resulting in groundwater and air pollution.Therefore,it is necessary to consider using tailings to prepare green environmental protection materials,which can not only save cost but also reduce energy consumption.Among them,foam glass as an inorganic thermal insulation material has attracted people's attention,and the foam glass prepared by tailings is undoubtedly one of the ideal choices for thermal insulation materials in construction industry.In this paper,the foam glass was prepared by using XiMeng molybdenum tailings as the main raw materials and introducing different dosage of foaming agent.The effects of the type and amount of blowing agents on the viscosity,thermal conductivity and morphology of foam glass during sintering progress were systematically studied.The result of theoretical model calculation was compared with that of the actually measured thermal conductivity of the sample.Specific research contents and experimental results are presented as follows:The liquid phase viscosity of molybdenum tailing foam glass of the sintered samples decrease with increasing SiC content?0³.0wt.%?,resulting in the increase of the pore size and the porosity,which enhances the overall expansion of the samples.It's remarkable that when CaCO₃?<4.0wt.%?was used as foaming agent with lower content,the liquid phase viscosity of the sample decreased initially during sintering;with the increase of CaCO₃contents?>4.0wt.%?,the temperature firstly increased at a high specific viscosity caused by the addition of CaCO₃,and the temperature decreased at low specific viscosity.However,the liquid phase viscosity of the sample during sintering will be reduced sharply when Na₂CO₃ is used as foaming agent.Compared with the experimental results,four analytical models were chosen to study thermal conductivity of the samples.It is indicated that the predicted result by parallel model is in good agreement with the experimental result.The sample prepared via sintering at 1150°C using 2.5wt.%SiC and molybdenum tailings exhibited a low bulk density of 0.37g/cm³,high porosity of 85.14%,and low thermal conductivity of 0.22W/m·K,which meets the requirements of the national thermal insulation material standard,meaning that the foam glass prepared from XiMeng molybdenum tailings can be regarded as heat insulators applying to construction industries.Moreover,the prepared foam glass in this study were almost made from slags?99.5⁹7wt.%?,releasing no harmful substances during the preparation,which is apparently a product of economical-saving and environment-friendly.Therefore,the preparation of foam glass may solve the problem of massive accumulation of molybdenum tailings.The decomposition foaming agent,such as CaCO₃ or Na₂CO₃,on the other hand,is not suitable for foaming glass prepared from molybdenum tailings with high silicon content because of their low porosity,high density and thermal conductivity.