To develop an efficient and clean technique for comprehensively utilizing potassic syenite resources exposed in the Eastern Qinling to Dabie area of China

a series of experiments were performed using a typical K-feldspar powder as raw material

with focus on the hydrothermal stability of microcline in KOH-H2O solution

reaction principle of preparing potassium sulfate

as well as processing by-products from alumina and silica residue. Microcline was easily transformed into kalsilite by dislodging 2/3 SiO2 of the K-feldspar in the solution

resulting in nearly hundred percent higher concentration of K2O in the solid product

from which nearly pure solution of potassium sulfate was then obtained by dissolution with sulfuric acid

and further potassium sulfate was crystallized by evaporation of the solution or by the alcohol precipitation method. The alkaline solution of mainly potassium silicate reacted with lime milk to precipitate calcium silicate hydrate

from which needle-shaped wollastonite powder was synthesized hydrothermally

and then by calcination. The alumina and silica residue were used to make calcined kaolin first by acidic washing

and then by calcination. The whole procedure developed in this research was simple and economical

with recovery ratio of K2O up to 94.0%. In such a way

the components of K2O

Al2O3

and SiO2 in K-feldspar of the ores were wholly transformed to valuable products

giving rise to maximum utilization of K-feldspar resources

and also minimum consumption of relevant mineral resources. The technique is noted for energy conservation

high efficiency and clean production.