Extraction of Potassium from Biotite by Ca2+/K+ Ion Exchange and the Structural Transformation

Abstract

In order to alleviate the contradiction between supply and demand of potassium resources in China, we extracted potassium from biotite by Ca2+/K+ ion exchange. Soluble potassium salts were obtained from the filtrate by hydrothermal reaction of biotite with oxidant, ion exchanger and other reagents at 80 ℃. The extraction rate of potassium and the structure change of biotite during the process of potassium exchange were determined by atomic absorption spectrophotometer and X-ray diffraction. The results showed that the layered silicate structure of biotite after ion exchange had not been destroyed, the base-plane spacing has expanded from 1.012 nm to 1.4288 nm, and most of the interlayer potassium ions have been extracted after 24 hours. The potassium extraction rate is 89%.