STRONTIUM EXTRACTION BY ALUMINOTHERMIC REDUCTION

Experiments are performed in a mechanically agitated molten bath of aluminium to extract strontium from strontium carbonate by aluminothermic reduction. The molten aluminium contains additions of magnesium or bismuth. Magnesium is added to the melt for two reasons: to increase the reactivity and to lower the surface tension of the molten alloy. Bismuth is added to lower the surface tension without altering the reactivity of the melt. The experimental conditions are: temperature, 1000-degrees-D; pressure, 1 atm; contacting time, 1 h. Results show that with a Mg:Sr molar ratio of 10:1, strontium recovery from the strontium carbonate feed to the excess aluminium is greater than 50%. Comparison between experiments with either magnesium or bismuth additions shows that the chemical effect of magnesium is predominant over the surface tension effect of bismuth or magnesium.