Hydrothermal decomposition process of K‐feldspar in NaOH solution

Abstract

This 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.

Rapid Zeolization of Potassic Rocks by Means of a Microwave‐Assisted Hydrothermal Method

“…By analyzing the phase transition process of the products synthesized at different reaction time, it can be determined that the zeolization of potassic rocks in NaOH solution of high concentration could be divided into three stages. The first stage is the decomposition of potassic rocks in NaOH solution and the formation of SOD (Equations (1–4)) [15] . The structure of potassic rocks is destroyed in the hot alkaline solution, and the Si, Al and K species are extracted from potassic rocks.…”

“…The first stage is the decomposition of potassic rocks in NaOH solution and the formation of SOD (Equations (1-4)). [15] The structure of potassic rocks is destroyed in the hot alkaline solution, and the Si, Al and K species are extracted from potassic rocks. Simultaneously, the Si and Al species are recrystallized into zeolite SOD in the hydrothermal system.…”