Development of an efficient precipitation process for product recovery from leach liquor of low-grade dolostone hosted uranium ore

India has a low-grade dolostone hosted strata bound type large uranium ore deposit in Southern Cuddapah basin in Andhra Pradesh. The host rock of this deposit predominately contains dolomite along with quartz, cellophane, chlorite, pyrite etc. Attempts were made for development of an optimized process for efficient recovery of uranium from this ore. A process was developed that has now been adopted on a commercial scale. The process comprising of oxidative alkaline pressure leaching followed by filtration and counter-current washing of leached slurry generates leach liquor of concentration less than 1 gpl of U₃O₈ with a high value of Total Dissolved Solid (TDS). Direct precipitation of Sodium Diuranate (SDU) from leach liquor generates an excessive amount of fine precipitates of morphology not conducive to efficient separation in continuous mode of operation. Ion exchange process for upgradation and purification of leach liquor prior to precipitation was not found effective due to poor loading and poor selectivity of uranium with commercially available ion exchange resins. An innovative process, compatible with the chemistry of alkaline leaching process has been developed after extensive experimental work in continuous mode of operation. Variations in precipitation efficiency were investigated as a function of reagent dosages and precipitation time. The attributes of the products such as their settling characteristic, particle size distribution & morphology, which influence separation of the product, have also been investigated. Under the optimized conditions, it was possible to obtain both precipitation and separation efficiencies of SDU in the order of more than 98%. This paper outlines the salient experimental results and their implications for SDU precipitation and its separation.