Abstract: Due to shortage of salt lake resource, over 50% of potash salt consumption in China relies on import, seriously challenging Chinas agricultural development and grain production security. Syenites with K2O grade up to 8.5%15.4%, are rich potassium resource, possessing 20 times higher predictive reserve potential than that of salt lakes. In mineralogy, this syenite-type potassium resource is consisted of potassium minerals such as microcline, nepheline and muscovite; geographically, it mainly distributes in the “QinlingDabie syenite zone” and “YanliaoYinshan syenite zone”. In this work, phase equilibria in KAlSi3O8-NaOH/KOH/Ca(OH)2-H2O systems were simulated by electrolyte solution thermodynamic software OLI Analyzer 9.2, and tested on representative potassic syenite samples by hydrothermal alkaline decomposition experiments. As a result, leaching ratio of K2O reached as high as over 85.6%. The obtained sodium and potassium silicate alkaline solutions were suitable for preparing various types of potash salts or eco-potash fertilizers; accordingly, the alumina-silicate components were transferred into products of precipitated calcium silicate, Na-/K-zeolites, wollastonite and kaolin, etc. By virtue of its cleanliness, high efficiency, high resource utilization rate, and environmental compatibility, the hydrothermal alkaline digestive method provides excellent technological support for the green and sustainable development of a new potash salt industrial system in China.

Key words:  syenite, K-feldspar, potassium resource, hydrothermal decomposition, potash salt industry, green development