ALTERNATIVE SOURCES OF POTASSIUM FROM POTASSIUM FELDSPARS, FROM MINING TO CROPPING: A REVIEW

This review examines thermal, hydrothermal, chemical, and biological processesfor producing This Thsreview examines thermal, hydrothermal, chemical, and biological processes for producing controlled-release potassium fertilizers exclusively from potassium feldspars. A comparative assessment is presented, covering extraction efficiency,environmental impact, and technological feasibility of the main activation routes. Among these, alkaline hydrothermal treatments and pyrometallurgical chlorination achieve the highest potassium extraction efficiencies, often exceeding 80% and reaching above 90% under optimized conditions. In contrast, moderate calcination and bioleaching show lower extraction rates but offer environmental and operational advantages, such as reduced energy demand, lower reagent consumption, and potential suitability for sustainable agricultural practices. Agronomic trials demonstrate that properly activated potassium feldspars can match the performance of conventional potassium chloride (KCl) in terms of crop yield, while providing the advantage of controlled nutrient release and prolonged residual effects in the soil. Economic and macroeconomic analyses emphasize Brazils strong dependence on imported potassium fertilizers and the strategic opportunity of exploiting domestic feldspar deposits.