engleski

Effect of TiO2 on sintering of magnesium oxide obtained from seawater

This study has examined the effect of the TiO2 addition on properties of magnesium oxide obtained from seawater by substoichiometric precipitation. The addition of dolomite lime, used as the settling agent, was 80% of the stoichiometrically required quantity. In sample preparation, the combined method of rinsing of the magnesium hydroxide precipitate was used (3+2), i.e. rinsing by decantation was done three times with alkalised distilled water with pH of 12.50 and twice with distilled water with pH of 6.74. Repeated rinsing on the filter paper (5 times) was done with fresh distilled water with pH of 6.74. Isothermal and activated sintering of MgO samples (80% precipitation) then took place without TiO2 addition, and with the addition of 5 and 8 mass % TiO2 at the temperature of 1700 oC during 1 hour, in order to determine the properties of these samples, particularly as regards the amount of B2O3 in samples after sintering. The results indicate that the addition of TiO2 in the amount of 5 mass % is sufficient to bind the CaO present and thereby lead to significant evaporation of B2O3 in the process of activated sintering of seawater-derived magnesium oxide. Samples became significantly denser during sintering, i.e. all the samples examined had very low open porosity.

substoichiometric precipitation; TiO2 addition; seawater; magnesia; activated sintering

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