A roast-leach process for extraction of rare earths from complex monazite-xenotime concentrates

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Separation Science and Technology

DOI:https://doi.org/10.1080/01496399508010386· OSTI ID:88719

Franken, K M ^[1]

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1. Bureau of Mines, Rolla, MO (United States)

The proposed process approaches the problem of solubilizing rare-earth phosphates (monazite and zenotime) found at the Pea Ridge iron mine in Sullivan, MO, from both a pyrometallurgical and hydrometallurgical point of view. It utilizes a roasting operation that converts the rare-earth phosphates to rare-earth oxides (REOs), which eliminates some costly and hazardous processing steps currently in practice. Different combinations of roasting temperatures and acid concentrations have been investigated to selectively extract the rare-earth values. Cerium is selectively solubilized by roasting at 427{degrees}C and leaching with a sulfuric acid concentration of 265 g/L. After the cerium is removed, the neodymium and lanthanum can be solubilized at a roasting temperature of 500{degrees}C and a sulfuric acid concentration of 88 g/L. Finally, neodymium, praseodymium, and yttrium are solubilized at a roasting temperature of 871{degrees}C and a sulfuric acid concentration of 265 g/L. Alternative leaching media, such as thiourea, sulfuric acid-doped thiourea mixtures, ammonium thiosulfate, nitric acid, and hydrochloric acid have also been investigated along with the addition of ultrasonic agitation. Using ultrasonics in addition to mechanical agitation, hydrochloric acid proved to be the best leaching medium. The best roasting temperatures for selective solubilization remained the same, but all of the leaching steps were conducted at 64 g/L hydrochloric acid.

• Sponsoring Organization: USDOE
• OSTI ID: 88719
• Report Number(s): CONF-931043--
• Journal Information: Separation Science and Technology, Journal Name: Separation Science and Technology Journal Issue: 7-9 Vol. 30; ISSN 0149-6395; ISSN SSTEDS
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
EXTRACTION
IRON ORES
LEACHING
MONAZITES
PHOSPHATES
PURIFICATION
RARE EARTH COMPOUNDS
ROASTING
XENOTIME