ALUMINA EXTRACTION FROM ALUMINO-SILICATE ORES AND POTASSIUM SULFATE ORES

摘要

Alumino-silicate ore and a potassium sulfate bearing ore such as polyhalite or langbeinite are reacted by reducing and then calcining. Reduction decomposes the reactants and produces H2S. Calcining produces a sinter containing potassium aluminate and silicates. The aluminate is leached from the sinter with KOH and/or K2CO3 solution and then precipitated to Al(OH)3 with SO2 or CO2. Subsequent calcining yields alumina; some of the potassium carbonate or sulfite is recycled back into the system and the balance is converted to potassium salts such as potassium sulfate or potash.