Process for production of commercial quality potassium nitrate from polyhalite

摘要

A method for the production of KNO3 from polyhalite is provided. The method comprises steps of decomposing said polyhalite into syngenite, gypsum, and soluble components, treating the solid decomposition products sequentially with HNO3 and Ca basic compound, precipitating the CaSO4 thus formed, and crystallizing the KNO3 from the solution remaining. The method recovers up to 75% of the potassium present in the raw polyhalite as KNO3 and substantially all of the remainder as a potassium magnesium sulfate salt.