Thermally promoted phosphate rocks I. Preparation and characterization

Abstract

Thermally promoted phosphate rocks (TPPRs) were prepared by heating four phosphate rocks (PRs) obtained from Jhabua, Mussoorie, Purulia and Udaipur alone or with two additives (Na2CO3 or KCl) in three ratios at four temperatures (300, 500, 700 and 900°C) for two hours. All the 112 TPPRs so prepared, were analyzed for total, citrate and water-soluble P contents. Characterization of TPPRs indicated that irrespective of the source of phosphate rocks, the total P content of TPPRs prepared with additives was less as compared to original phosphate rocks. In general, Jhabua PR registered the highest total P content. The total P content increased with increase in temperature, but decreased with increase in the PR to additive ratios. TPPRs of Na2CO3 registered higher amounts of total P as compared to KCI. Water and citrate soluble P contents of TPPRs increased with increase in temperature, and PR to additive ratios. Among the four phosphate rocks, Mussoorie PR recorded the highest amount of water and citrate soluble P in heated-products. TPPRs obtained with Na2CO3 registered higher amount of water and citrate soluble P contents as compared to those prepared with KCl. The X-ray diffractograms of TPPRs indicated the presence of citrate soluble NaCaPO, and water soluble Na2PO3 in the products obtained from PR-Na2CO3 mixtures heated at 900°C.