Effect of tetracarbon additives on gibbsite precipitation from seeded sodium aluminate liquor

Effects of tetracarbon additives, 1-butanol, 1,4-dioxane and tetrahydrofurane on gibbsite precipitation from caustic seeded sodium aluminate liquor were investigated. The additive was charged into supersaturated seeded sodium aluminate liquor, then the precipitation ratio of aluminate liquor in 10 h was evaluated and compared, and the particle size distribution of product was measured. The Mulliken atomic charge of oxygen in the additive molecule was calculated with DMol3 program. The results show that 1-butanol has little effect on gibbsite crystallization, while the precipitation ratios under the effect of 1,4-dioxane and tetrahydrofurane are 1.7% and 3.6% higher than that of the blank, respectively. The agglomeration efficiency of the product is also enhanced obviously by the addition of 1,4-dioxane and tetrahydrofurane. The precipitation ratio is inversely proportional to Mulliken atomic charge of oxygen atom, which implies that functional group in the additive molecule is involved in the gibbsite precipitation process more fundamentally than carbon chain.