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Patent US10640847
Issued 2020-05-05
Recovery Of Rare Earths From Concentrates Containing Fluorine
The present invention relates to the recovery of rare earths, scandium, niobium, tantalum, zirconium, hafnium, titanium, and the like from ores or concentrates containing fluorine. More specifically, the ores or concentrates are pretreated by carbochlorination to convert the rare earths and other metals into their chlorides and then subjected to dilute hydrochloric acid leaching to recover the valuable rare earths and other metals from the leachate. Niobium, tantalum, zirconium, hafnium, and titanium can be recovered as their chlorides or oxychlorides from the gaseous products of carbochlorination, or converted into their oxides while simultaneously regenerating chlorine.
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- 1. A method of recovering a mineral from a fluorine-containing ore or concentrate, the method comprising:
treating the fluorine-containing ore or concentrate by carbochlorination in the presence of a carbon-containing material and a fluorine capturing agent to form a mineral chloride and a treated ore or concentrate, wherein the fluorine capturing agent prevents formation of rare earth fluorides by forming a fluoride more thermodynamically stable than rare earth fluorides during carbochlorination; contacting the treated ore or concentrate with a HCl leach solution to solubilize the mineral chloride in the leach solution; and recovering the mineral, wherein the mineral is selected from the group consisting of a rare earth mineral, a scandium mineral, a niobium mineral, a tantalum mineral, a zirconium mineral, a hafnium mineral, a titanium mineral, and combinations thereof, and wherein fluorides remaining in the treated ore or concentrate after the treating step are insoluble in the HCl leach solution.
- 11. A method of recovering a mineral comprising at least one of scandium, niobium, tantalum, zirconium, hafnium, titanium, and a rare earth element from a fluorine-containing ore or concentrate, comprising:
(a) agglomerating the fluorine-containing ore or concentrate with a carbon-containing material, a fluorine capturing agent, and a binder to produce an agglomerate; (b) carbochlorinating the agglomerate by exposing the agglomerate to chlorine gas to produce a calcine; (c) leaching the calcine by contacting the calcine with a hydrochloric acid solution having a pH of less than about 4.0 to produce a mixture of a liquid and a solid; and (d) recovering the mineral by contacting the liquid of the mixture with at least one of sodium hydroxide, ammonium hydroxide and magnesium hydroxide, wherein the fluorine capturing agent prevents formation of rare earth fluorides throughout step (b).
- 21. A method of recovering a mineral from a fluorine-containing ore or concentrate, the method comprising:
treating the fluorine-containing ore or concentrate by carbochlorination in the presence of a carbon-containing material and an fluorine capturing agent precursor to form a mineral chloride and a treated ore or concentrate, wherein a fluorine capturing agent is formed in situ by carbochlorination of the fluorine capturing agent precursor and the fluorine capturing agent prevents formation of rare earth fluorides by forming a fluoride more thermodynamically stable than rare earth fluorides during carbochlorination; contacting the treated ore or concentrate with a HCl leach solution to solubilize the mineral chloride in the leach solution; and recovering the mineral, wherein the mineral is selected from the group consisting of a rare earth mineral, a scandium mineral, a niobium mineral, a tantalum mineral, a zirconium mineral, a hafnium mineral, a titanium mineral, and combinations thereof, and wherein fluorides remaining in the treated ore or concentrate after the treating step are insoluble in the HCl leach solution.
