Abstract
This study evaluated the use of phospho-gypsum pond water to pre-react phosphate ore associated with phosphoric acid production via the wet process. The objective was to improve phosphate recovery and aid in the management of pond water inventory. The non-catalytic heterogeneous solid-liquid reaction kinetics were examined associated with carbonate in the ore and the acidic phosphate, fluoride and sulfate present in pond water. Additionally, the sedimentation and dewatering characteristics of phosphate ore slurry were evaluated to determine the feasibility of recovering neutralized pond water and returning ore slurry back to an acceptable solids concentration ready for acidulation with sulfuric acid. The reaction kinetics between acidic process water and phosphate ore exhibited zero and first order reaction behavior and Arrhenius temperature dependence. Additionally a mixture of hydro-cyclones, gravity thickening and centrifugation proved to be feasible options for separating neutralized process water effluent and re-concentrating phosphate ore slurry.