Aqueous alteration of potassium-bearing aluminosilicate minerals: from mechanism to processing

The anticipated increase in demand for potassium fertilizers and alumina from developing nations experiencing a high-rate of population growth brings a global sustainability concern. Most of these countries do not have economically viable resources for both commodities; and the environmental footprint of existing technologies may compromise local ecosystems. Alternatives, both in terms of resources and extraction technologies, are therefore needed. Aqueous alteration of potassium-bearing aluminosilicate minerals has been proposed as an alternative to both traditional K-fertilization and alumina production. This work discusses the mechanism of aqueous alteration of aluminosilicate minerals, and the chemical processes that have been proposed to date. Although extensive studies are found in the fields of geochemistry and materials chemistry, their results have rarely been analysed and engineered to allow a proper control and design of chemical processing. The review suggests that such a multi-disciplinary approach is required to enable new technologies that both comply with green chemistry principles and are economically viable.