Effect of grinding on synthesis of MgAl 2O 4 spinel from a powder mixture of Mg(OH) 2 and Al(OH) 3

Abstract

Dry grinding of the powder mixture composed of magnesium hydroxide and gibbsite using a planetary ball mill followed by its heating was conducted to prepare MgAl 2O 4 spinel. Both the starting materials are easily converted to amorphous phase by intensive grinding within 60 min. The monolithic MgAl 2O 4 spinel phase can be obtained from the mixtures ground over 15 min by calcination at 900°C. The reactivity of the mixtures ground over 30 min is not improved. Prolonged grinding promotes the aggregation of ground fine particles, but the aggregates deflocculate into fragments after calcination.