Production of Potassium Chloride from K-Feldspar Through Roast–Leach–Solvent Extraction Route.

This work focuses on extraction of potassium from feldspar through pyro-hydrometallurgical route. Calcium chloride was used as roasting agent for feldspar. Effect of various operating variables, viz. time, roasting temperature and CaCl₂ dose on extent of roasting, were thoroughly studied. Roasting 10 g of feldspar with 17 g of CaCl₂ at 900 °C for 1 h resulted in 99.9% conversion of K₂O to KCl. Order of feldspar roasting was found to be around 2, and activation energy requirement was 136.6 kJ/mol. Calcium and sodium were leached along with potassium from chloride-roasted K-Feldspar with water at room temperature. To generate a pure solution of potassium from the leach liquor containing K, Ca and Na, it was selectively extracted from leach liquor by using dibenzo-18-crown-6 ether as extractant and m-cresol as diluent. Loading of potassium was carried out at an A/O ratio of 2:1, while stripping was carried out in water at O/A ratio of 2:1. 99.5% pure crystals of KCl were obtained on evaporation of the strip solution. A schematic flowsheet has been provided for the preparation of pure KCl from feldspar. [ABSTRACT FROM AUTHOR]