Summary How Thorium is initially refined and separated
- Acid Digestion – solvent digestion and extraction, precipitation and centrifuges
- Selective Filters – using materials like Tuned Carbon and Ligins
- Base Alkali – Alkaline Digestion Extraction, Precipitation via titration
- Thorex process, for spent fuel – employs tributyl phosphate extraction chemistry. Irradiated fuel, containing either thorium metal or oxide, is dissolved in nitric acid containing a small amount of fluoride ion.
- Silex for Thorium – there has been some research into the possibility that a silex laser separation type process could be used for extraction of Thorium as well a rare earths
Processes for Reduction to Pure Metallic Thorium
- Induction Furnace – The process of using an Induction Furnace in inert Environment to reduce Thorium Oxide to pure Thorium Metal is described in a video by Stephen Boyd at the Thorium Energy Alliance Conference 6, 2014. Chicago Illinois Loyola University.
What Minerals Thorium is refined from:
Thorite, Thorianite – Rare, not used commercially but does have extremely high concentrations of Thorium, Uranium as well as Rare Earths.
Thorianite and uraninite form a complete solid solution series in synthetic and natural material The division between the two species is at Th:U = 1:1 with U possibly making up to 46.50% and Th ranging up to 87.9%. Rare earths, chiefly Ce, substitute for Th in amounts up to 8% by weight Ce is probably present as Ce4+. Complete series is known in synthetic material between CeO2 – PrO2 – ThO2 – UO2. Small amounts of Fe3+ and Zr also may be isomorphous with Th. Pb present is probably radiogenic.
Thorium Bearing Carbonate Minerals include:
Bastnäsite is one of a family of three carbonate-fluoride minerals, which includes bastnäsite-(Ce) with a formula of (Ce, La)CO3F, bastnäsite-(La) with a formula of (La, Ce)CO3F, and bastnäsite-(Y) with a formula of (Y, Ce)CO3F.
Bastnasite has a low Thorium content making it attractive to process from a waste profile, however these carbonate minerals do not have a good distribution spread of Heavy Rare Earths that are most needed.
Thorium Bearing Phosphate minerals include:
- Triphylite Li(Fe,Mn)PO4
- Monazite (La, Y, Nd, Sm, Gd, Ce,Th)PO4 ,rare earth metals
- Erythrite Co3(AsO4)2·8H2O
- Amblygonite LiAlPO4F
- Xenotime-Y Y(PO4)
- Apatite group Ca5(PO4)3 (F,Cl,OH)
- hydroxylapatite Ca5(PO4)3OH
- fluorapatite Ca5(PO4)3F
- chlorapatite Ca5(PO4)3Cl
Thorium Bearing Ionic Clays
Very little Thorium and other actinides are found in Ionic Clays making them very attractive sources of Rare Earths. Due to the high volumes of processed clays for the Rare Earth content, China now has a significant stockpiles of Thorium Nitrate. The most well known source for these clays are in the Baotou region of Mongolia, China.