Phosphorite deposits in India and their beneficiation

Abstract

The total annual requirements of phosphate rock by the end of fourth plan are expected to be 4.5 million tonnes. India imported in 1967 phosphate rock costing Rs.96 millions in foreign exchange. The intensive search by GSI for new sources has revealed phosphorite deposits at Kanpur, Dakan-kotra, Jhamar-Kotra, Maton, etc., in Rajasthan and at several other localities in Uttar Pradesh and Himachal Pradesh. India has reserves of phosphate rock, according to available data, of about 220 million tonnes as of 1969. Typical chemical analyses of some world's major deposits are compared with that of Indian phosphorites, from the fertilizer manufacturing point of view. Majority of the Indian deposits are below acid-grade (<31.5% P2O5) and are high in the deleterious contents like Fe2O3, Al2O3, MgO and free carbon, needing beneficiation. Suitable methods of beneficiation for Mussourie, Maldeota and Kanpur deposits have been proposed for obtaining acceptable acid grade concentrates. Mussourie rock which has cherty and quartzitic tabling and oleic acid-flotations. But in the case of Rajasthan rocks having calcite gangue, suitable calcination methods have been developed. From a Kanpur rock assaying 16.4% P2O5, concentrates assaying around 34% P2O5 were obtained with good recovery. This concentrate met with the specifications of an acid-grade material. Maldeota rock containing calcite gangue plus some pyrite was found to be not easily amenable to beneficiation. (Ch. Rambabu and K.K. Majumdar, Ore dressing section, Metallurgy Division, Babha Atomic Research Centre, Trombay-85)