关键词: 霞石正长岩, 碳酸钠, 烧结反应, 硅铝分离, 氧化铝

Abstract:

Nepheline syenite is an important kind of mineral resource rich inK₂O, Al₂O₃and SiO₂. Thermodynamic calculation shows that the temperature of the sintering reaction is around 800 K(527 ℃), with sodium carbonate as the additive, and the products are mainly NaAlSiO₄, KAlSiO₄ and Na₂SiO₃. The sintering experimental results show that the decomposition temperatures of the major aluminosilicate minerals in the nepheline syenite are ranging from 1,073 to 1,123 K(800-850 ℃), and the products are those as expected. The decomposition rate of minerals in the nepheline syenite is over 95%. Leaching experiments of the sintered products by acidic solution show that the separation of silica and alumina by the current procedure is superior, with extraction rates of SiO₂, Al₂O₃ and K₂O up to 91.4%, 92.2% and 92.5% respectively. The technique developed in this paper is therefore a process with less energy and raw mineral resource consumptions, and cleaning production, compared with the Russian limestone-sintering technique.

Key words: nepheline syenite, sodium carbonate, sintering reaction, separation of silica and alumina, alumina