THERMAL AND CHEMICAL PROCESSING OF SILICATE ROCK FOR POTASSIUM RELEASE

Abstract

Potassium is vital for the growth of healthy plants and crops. India does not have any commercial resources of potash, a large quantity is imported every year from the global market to meet the agricultural demand. In this context, the extraction of potassium values from different indigenous sources is highly essential. Available potassium source in India are only silicates minerals in which potassium is present in insoluble form which are widely available. A silicate K-rock from Banda (Uttar Pradesh) is procured. Detailed characterization is carried out using optical microscopy, XRD, TG/DTA and FESEM/EDS. The major phases are muscovite, orthoclase, phologopite, rutile and quartz. Potash bearing mineral are muscovite, orthoclase and phlogopite and contains approximately 9.08% K2O. Extraction of potassium from complex silicate structure has been done using following possible routes, heat treatment using muffle furnace, microwave assisted heating and through mechanical activation using planetary ball mill followed by heat treatment in muffle furnace. In each route optimisation of flux dosage, temperature and time has been done. Using muffle furnace maximum potassium extraction of 83% was achieved by CaCl2 (fused) treated sample whereas in mechanical activation followed by muffle furnace it was 84.52%. Extraction percentage was same for both the case but temperature required for treatment was reduced from 900°C to 700°C. Same was the case for NaOH treated sample, temperature for treatment came from 600°C to 300°C in addition to potassium extraction reached to 87%. This outcome gave indication that mechanical activation has vital role in the liberation of K from the structure so the parameter in mechanical activation was varied , so after varying the milling time using CaCO3 as flux, K extraction was achieved 91% without any heat treatment.