DISSOLUTION BEHAVIOUR OF POTASSIUM FROM MICACEOUS MINERALS

Abstract

Potassium (K) is one of the essential elements for the growth of plants and thereby for humans. It is vital for many plant functions such as carbohydrate metabolism, enzyme activation, osmotic regulation and protein synthesis. In fertilizers, potash demand has been steadily increasing at ~3.5% annually. Water soluble potash deposits are rare and highly localized. India is neither present on the world potash production map nor it has adequate soluble potash rich deposits such as sylvite, Sylvinite, carnalite etc. The K-bearing minerals are recovered either by using conventional underground mining methods or through solution mining methods. At present, India is importing all its potash (about 2 million tons per annum) from different countries. However, India possesses a vast resource of micaceous minerals in the form of glauconite and it is mainly found in Madhya Pradesh, Gujarat, Uttar Pradesh, Rajasthan and Uttarakhand. These rocks are basically a group of alumino silicate of potassium, sodium and calcium (K2O%: 5-12, Na2O%:0-1%, SiO2%: 52-60, Al2O3%: 15-20, Fe2O3%, 5-9, MgO%: 1-2). The K extraction from these minerals has received little attention probably due to lack of scientific know how, economic considerations and not much awareness. It is important to exploit these resources to substitute some import of potash in the country and to provide self-dependency in potash production. The strong chemical bonding of potassium in these minerals makes the mineral dressing route futile. In present work, an attempt has been made to extract potassium in form of some soluble salt under different routes such as acid leaching, thermal treatment with and without fluxing agents followed by leaching, microwave treatment and mechanical activation. These different treatments are targeted to increase K availability/solubility which is related to the modifications in mineral structure and possible exchange reactions of the suitable ions in the system. The modifications in the feed sample and treated samples are studied through SEM-EDAX, XRD, EPMA, TGA/DTA and Optical Microscope. With the combination of suitable fluxes and treatments, it is possible to get up to 96% K dissolution.