Monazite decomposition

Alkaline breakdown of monazite. —The flowsheet for the process is given in Fig. 5. For this process it is necessary to remove calcium from the monazite by boiling the mineral with nitric or hydrochloric acid. It has long been known that monazite can be attacked by alkali. Rohden and Peltier [149] have shown the practical applicability of the alkali process for monazite decomposition. The optimum conditions necessary for alkaline decomposition of monazite have been extensively studied by Kaplan and his coworkers [150—153]. 

Buckwedel, T. W. Decomposition of monazite. Effect of a number of variables on the decomposition of monazite sand with sulphuric Add. I.S.C.—66. 

Production The most important base minerals are xenotime, monazite, and bastnasite. The first two are orthophosphate minerals LaP04 and the third is a fluoride carbonate LaCOsF. Lanthanoids with even atomic numbers are more common. Monazite also contains thorium and yttrium which makes handling difficult since thorium and its decomposition products are radioactive. 

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