An Alternative Alkaline Fusion Process for the Production of Heavy Rare Earth, Thorium, Uranium and Phosphate from Malaysian Xenotime

摘要

Xenotime is a rare earth phosphate mineral which contains significant amounts of yttrium. Currently, the method of xenotime cracking involves the use of concentrated sulphuric acid, which is hazardous towards the environment. This paper presents a study where an environmental friendly, alternative process to extract rare earths is developed. This method uses diluted hydrochloric acid (HCl) during the dissolution stage to replace hazardous sulphuric acid currently in use. This change was made possible by incorporating an alkaline fusion stage prior to the acid dissolution stage, which helps improve the leachability of yttrium and other rare earths elements. Selective and fractional hydroxide precipitation stages were also included in the process to separate the yttrium from the natural radioactive uranium and thorium elements that are also present in the xenotime mineral. An added advantage to this process is the production of trisodium phosphate and uranium concentrate as by-products from the process.