Hydrothermal decomposition process of K‐feldspar in NaOH solution

Abstract

AbstractThis work investigates the decomposition of K‐feldspar into analcime under alkaline hydrothermal conditions. Two types of raw materials, potassic syenite powder and microcline crystal lumps, were used for hydrothermal treatment. Research techniques of minerals alteration path simulation, powder decomposition experiments, and specific observations were conducted. Results show that K‐feldspar did not alter into analcime directly under hydrothermal conditions, and instead, hydroxycancrinite was an important intermediate. Formation route of analcime from potassic syenite powder was derived as follows: syenite dissolution → hydroxycancrinite precipitation → hydroxycancrinite assembling → reversed recrystallization → analcime, where the assembling of hydroxycancrinite into analcime‐shaped spheres was the key step for analcime formation. Above all, a novel and different to natural reaction process with feldspar decomposition and analcime formation process was proposed.