engleski

Activated sintering of seawater-derived magnesia

This study has examined the effect of the TiO2 addition and the effect of the method used to rinse the magnesium hydroxide precipitate on the properties of magnesium oxide obtained from seawater by substoichiometric precipitation (which took place with 80 % of the stoichiometric quantity of the dolomite lime). The combined rinsing method (3+2) was applied to rinse the magnesium hydroxide precipitate, i. e. the rinsing by decantation was carried out three times with alkalised distilled water with pH = 12.50 and two times with distilled water with pH = 6.7. The MgO samples (80 % precipitation) obtained were then sintered with the addition of 0.5 and 1 mass % TiO2 in order to determine the properties of the sintered samples (density, porosity, the B2O3 content) relative to the method used for rinsing the magnesium hydroxide precipitate and to the effect of added TiO2. It has been established that all the samples sintered at 1700 oC with 3 h of soaking at the maximum temperature had very low porosity, and density up to 99 % of the theoretical density. The effect of added TiO2 in mass fractions 0.5 and 1 % on the B2O3 content was not very significant, which is related to the quantity of CaO in the examined samples.

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

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