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Mathematical modelling in the process of sintering MgO from seawater

Magnesium oxide obtained from seawater by substoichiometric precipitation, with the addition of 80% of dolomite lime as the precipitation agent was used in the present study. The sintering process was conducted at temperatures of 1400, 1500 and 1700 oC for the duration of 1, 2 and 4 h and the addition of 1, 2 and 5 wt % TiO2 with the purpose of establishing a mathematical model between the B2O3 mass fraction as the dependent variable and independent variables of the temperature of isothermal sintering, the isothermal sintering time and the mass fraction of the added TiO2. The B2O3 mass fraction in sintered MgO samples changes with the change in the parameters of activated sintering. Compared to the B2O3 mass fraction in calcined MgO sample, the percent of B2O3 evaporated from the sintered samples increases both with the increase of the duration of isothermal sintering and with the increase of the sintering temperature and the mass percent of TiO2 added. Different techniques have been used for characterization of the sintered MgO samples. The addition of TiO2 leads to formation of CaTiO3 and MgTiO4 which has been detected by the XRD analysis. The SEM/EDS analysis of MgO samples detected the presence of CaO and confirmed the results obtained by the XRD analysis. The chemical analysis detected the presence of CaO and B2O3 as impurities. The TiO2 reaction with CaO reduces the amount of CaO available to react with B2O3, therefore a higher amount of B2O3 can evaporate during the sintering process. The correlation and regression analysis was performed on the experimental data using the Statistica 7 mathematical package. Multiple regression models were examined in order to obtained the best regression equation (higher determination coefficient R2, lower standard estimate errors and it met the conditions imposed by the residual analysis). This relationship among all the factors of sintering makes it possible to predict the B2O3 content in the final product of MgO.

sintering MgO from seawater, mathematical modelling, substoichiometric precipitation, TiO2 addition

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