Uranium from Rare Earths Deposits
(Updated July 2014)
- A large amount of uranium is in rare earths deposits, and may be extracted as a by-product.
- Higher uranium prices and geopolitical developments have enhanced the economic potential for recovering these.
In addition to the 5.4 million tonnes of uranium in known recoverable resources, there are substantial amounts comprising what is known as "unconventional resources". One of these is rare earths, in relation to which China has a preeminent position as supplier. This gives rise to commercial pressure for development of other deposits outside China. Some of these contain significant uranium mineralisation.
Rare earth elements (REE) are a set of seventeen chemical elements in the periodic table, specifically the fifteen contiguous lanthanoids plus the lighter scandium and yttrium. Scandium and yttrium are considered REE since they tend to occur in the same ore deposits as the lanthanoids and exhibit similar chemical properties. Most REEs are not rare. However, because of their geochemical properties, REE are typically dispersed and not often found in concentrated and economically exploitable forms. REEs are often found together, and are difficult to separate. One of the minerals involved in the progressive discovery and identification of REEs was samarskite – containing uranium. Many more contain thorium.
Economically and geologically there is a distinction between light REE, or cerium earths (scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium – elements 21, 57-64) and heavy REE, or yttrium earths (yttrium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium – elements 39, 65-71). Gadolinium and europium apparently can fall into either category.
Large orebodies of the cerium earths are known around the world, and are being exploited. Monazite includes cerium, and associated light REE. Corresponding orebodies for heavy REE or yttrium earths tend to be rarer, smaller, and less concentrated. Most of the current supply of yttrium originates in the "ion adsorption clay" ores of Southern China. Some of these provide concentrates containing about 65% yttrium oxide, with the heavy lanthanides. Uranium ores from Ontario have occasionally yielded yttrium as a byproduct. Xenotime incorporates yttrium and heavy REEs.
Since 1998 China has produced over 80% of the world's REE, mostly from Inner Mongolia, and the proportion is now higher. All of the world's heavy REE (such as dysprosium) come from China. Most REE is by-product from Chinese sources such as the polymetallic (iron-REE-niobium) Bayan Obo deposit in Baotou city with reserves of at least 48 million tonnes of REE grading about 6%, but predominantly light REE. There are also limited surficial clay deposits in southern China, and two in Jianxi province are exploited: Longnan, with heavy REE similar to xenotime, and Xunwu, with light REE particularly lanthanum but with little cerium.
China cut back exports of all REE from the 35,000 t level in 2010, and banned exports of terbium and dysprosium. This led to recommissioning of Molycorp's Mountain Pass mine in California, and enhanced interest in bringing new orebodies into production, including Mount Weld in Western Australia, Nolans Bore in Central Australia and Kvanefjeld in Greenland, the latter two with significant uranium content with the rare earth oxides (REO). Molycorp is spending $781 million on modernising and expanding its plant, which will reach 19,000 t/yr capacity in 2012 – slightly more than US demand – and 40,000 t/yr in 2013.
In April 2011 China's Ministry of Industry & Information Technology (MIIT) under the National Development & Reform Commission (NDRC) set a production quota for REO of 93,800 tonnes, up 5% on 2010, with a quota on REO smelting of 90,400 tonnes. No new mining licences were to be granted before mid 2012. MIIT says that no extra production beyond the quotas will be allowed. In mid 2011 Baotou Steel Rare-Earth plans to acquire four rare-earth separation companies licensed by the Inner Mongolia government. This is part of the national government's effort to consolidate China's rare-earth sector, gain more influence over pricing in the global market and ensure sustainable growth in the industry. The Ministry of Land and Resources said that 15 southern cities with abundant heavy REE resources have signed agreements to cooperate in regulatory enforcement, and this may be under Baotou, at least in Fujian and Jiangxi provinces with heavy REE.
In May 2011 Areva signed a memorandum of understanding (MoU) with international chemical company Rhodia to develop deposits containing a mix of uranium and rare earth elements. The companies said that they will "combine their respective expertise and competencies to put together joint offers for the development and exploitation of hitherto unworked deposits containing the two strategic resources." They could eventually cooperate in conducting joint technical audits or studies of identified deposits, create joint ventures or co-participate in mining projects carried out by Areva or third parties.
Considering rare earths alone, China has 36 million tonnes (37.8%) of the world’s economic resources for rare earth oxides (REO), followed by Russia with 19 million tonnes (almost 20%) and the USA with 13 million tonnes (13.7%), according to Geoscience Australia. It also states that the largest REE deposit in the world is the Bayan Obo deposit in China, with at least 48 million tonnes of REO out of a world total of 95.27 million tonnes.
Particular deposits and projects
Mountain Pass, California
Molycorp’s Mountain Pass deposit was discovered by a uranium prospector in 1949. It dominated worldwide REE production from the 1960s to the 1990s, and is being recommissioned to again be a major producer from 2014. Remaining resources are about 1.6 million tonnes REE averaging 8.24%, with 5% cut-off. The company makes no mention of uranium as by-product.
Kvanefjeld, Ilimaussac complex, southern Greenland
Kvanefjeld is the main REE deposit with major potential for uranium production, with Sorensen and Zone 3 orebodies in the same Ilimaussac complex. It was investigated intensively over 1955-86, then dropped for commercial reasons. Greenland Minerals & Energy acquired the project in 2007 then with a JORC-compliant resource then of 43,000 tU at 0.022% U with 6.5 million tonnes of REO at 1.07% in Lujavrite. About 3.6% of REOs are terbium, dysprosium and yttrium, ie 'heavy'. The full Kvanefjeld uranium resource (JORC compliant) is now estimated at 101,000 tU indicated resources at 0.023 %U, 120,000 tU inferred resources, both with 0.015% U3O8 cut-off, and 10.3 million tonnes of REO including 0.37 million tonnes of heavy REO. The company has demonstrated over 90% co-recovery of REOs via effective beneficiation of concentrates followed by atmospheric sulfuric acid leach and solvent extraction recovery. This will lead to hydrogen reduction of uranium minerals and beneficiation followed by acid leach for REOs including yttrium. The Kvanefjeld deposit also has 2.25 Mt zinc as potential by-product.
Pre-feasibility study suggested annual production of 1000 tU with about 40,000 t REO as well as zinc concentrate, from a large open pit mine. Project cost is expected to be $1.53 billion. A definitive feasibility study is proceeding to mid 2013, concurrently with pilot plant trials, environmental impact assessment and social impact assessment. In August 2012, tests showed that flotation beneficiation would allow the concentrate to be exported for straightforward hydrometallurgical treatment if desired. The mine and concentrator part of the feasibility study was completed early in 2013 and the company is now finalising the environmental and social impact assessment and preparing an application to the government to proceed with the project. Construction could commence in 2015 with first production in 2018. Subsequent expansion to 6 Mtpa is envisaged.
The current proposal is for the mine and concentrator with flotation circuit to produce a REE-U concentrate plus zinc and fluorspar by-products. The concentrate comprising 8.5% of the milled ore and containing 15% REO and 0.25% U could be exported to a dedicated refinery to produce 23,000 tonnes of mixed rare earth carbonate (15% of this heavy REO) and 425 tU per year in stage 1. Alternatively light and heavy REOs could be separated at site. Start-up costs for a 3 Mtpa plant are estimated at $810 million - $450 million for mine and concentrator and $350 million for the refinery. Unit production costs are low for REOs and an incremental cost of $37/lb U3O8 for the uranium initially, falling to $31 if the production rate doubles. The metallurgical flowsheets for both concentrator and refinery were finalised in 2013.
The company had been seeking partners for the offshore refinery and in March 2014 signed an agreement with NFC, a subsidiary of China Non-Ferrous Metal Mining Group (CNMC) to provide concentrates of heavy REOs to NFC’s new 7000 tpa rare earth separation facility in China. Stage 1 of Kvanefjeld REE concentrate production would be sufficient to supply heavy REE for the full capacity of NFC’s initial plant, with the much greater quantity of light REE being stockpiled or sold. However, uranium is not included in the NFC agreement at this stage.
There is considerable further mineral potential in the immediate area – up to 600,000 tU according to IAEA estimates. As well as Kvanefjeld and adjacent Steenstrupfjeld, Zone 2 (6 km north) and Zone 3 were identified in 2011 within the project area. In March 2012 the company announced Zone 2 (now Sorensen) inferred resources in the same geology of 62,440 tU at 0.015% cut-off (av 0.03%) and 2.67 Mt REOs. In June, initial Zone 3 inferred resources of 24,300 tU and 1.1 Mt total REO were added. This took the project total to 221,600 tU, 2.24 Mt zinc and 10.3 Mt REO including 370,000 t heavy REO with 840,000 t Y2O3. Zone 3 has the same geology and its similar mineralisation outcrops extensively, with higher grade portions near surface.
A year after the Greenland government allowed the company's feasibility studies to include uranium, in December 2011 it amended the company's exploration licence to include uranium. The company could then apply for a mining licence including uranium, with a view to first production in 2016, followed by a long mine life. The company is conducting detailed discussions under confidentiality agreements with several international consortia regarding development scenarios and their funding. In November 2012 the Greenland government voted unanimously to support the project, including uranium, and in October 2013 it repealed the long-standing policy banning uranium development. It noted that it is Denmark's responsibility to ensure that international conventions, such as non-proliferation, are respected. Denmark is pursuing this, and both states expect to have a cooperation agreement for the mining and export of uranium finalised in 2014. The IAEA Additional Protocol for Greenland entered into force in March 2013.
The company is involved with the EU-funded EURARE program, designed to support the development of REO deposits in Europe. The Kvanefjeld project has been selected by EURARE as a major one for demonstration of REO production, and a 30-tonne ore sample is being processed accordingly. This is about 1.3% REO, which will be concentrated in Finland to 15% REO, which will be refined at Aachen in Germany to give a mixed carbonate of 60% REO. At Aachen a separation plant will sort the Pr+Nd from La & Ce and from SEG and heavy mix. The products will be evaluated.
Eco Ridge, Elliot Lake, Ontario
Pele Mountain Resources Inc has received mining leases for its Eco Ridge uranium and REE orebody in Canada, 11 km east of Elliot Lake. In the decade to closure of the Stanleigh mine at Elliot Lake in 1996, the area produced REE as a commercial by-product of uranium production. The Eco Ridge deposit contains a full range of REE at 0.164% grade, including 9.5% heavy REE (including scandium, europium and gadolinium in this category, 7.4% if excluding them). Uranium grade is 0.041% U with cut-off grade 0.024%. Some 65% of the heavy REE report in the uranium leach solution without any additional milling cost. The deposit includes indicated resources of 36,600 t REO and 8690 tU, plus 56,900 t REO with 14,500 tU inferred resources (NI 43-101 compliant). An underground mine is envisaged, using underground bio-leaching and surface heap leaching, the ore being moved to the surface in haul trucks. The leachate from underground and surface will be piped to the processing facility where it will be clarified and processed in a solvent extraction circuit. Solvent extraction raffinate will be recycled to the two leach operations. A preliminary economic assessment in 2012 suggested uranium production of 10,500 tU over 11 years.
Nolans Bore, Northern Territory, Australia
This is a deposit of light REE with 7500 tonnes uranium content at 0.016% U with 1.2 Mt REO grading 2.6%, about 135 kilometres north of Alice Springs, NT. It also contains 5 Mt of P2O5 and some thorium. Arafura Resources intends to develop it as a REE mine and plans to rail its concentrate at Whyalla, South Australia where it will be processed to produce 20,000 t/yr REO, 130 t/Uyr, plus phosphoric acid and gypsum co-products. The thorium will be separated as an iron-thorium precipitate and transported back to the Nolans Bore mine site in NT for long-term storage as a possible future energy source.
Dubbo Zirconia Project, New South Wales, Australia
Alkane Resources' DZP has REE as potential by-product of zirconium production – 700,000 t zirconia as measured resources in 2011. These have 0.75% REO and 0.014% uranium – about 4200 tU, and the same in inferred resources. The 2012 reserve figures also have 0.75% REO at same tonnage but do not include uranium.
Firawa prospect, Guinea, West Africa
Forte Energy NL has announced 7500 tU JORC-compliant inferred uranium resource at 0.025% U at Firawa, with 1-2% rare earth elements present which are as yet unquantified.
Zandkopsdrift, South Africa
Frontier Rare Earths in 2011 reported NI 43-101 resources of 950,000 t REE (56% indicated resources) at this deposit in the Northern Cape Province. The resource includes 47 ppm U, which is more likely nuisance than by-product. Frontier has signed a definitive agreement with KORES to develop the project as a partner with Frontier, initially taking 10% equity but with option to go to 50% and to take a proportional amount of production. The equity change is to follow the results of a positive Definitive Feasibility Study on Zandkopsdrift currently scheduled for late 2013. This will have updated NI 43-101 compliant reserves figures. KORES is to arrange project finance for the entire development.
Steenkampskraal, South Africa
During the 1950s and to 1963 about 50,000 tonnes of monazite concentrates were extracted which had between 3.3 and 7.6% thorium. Great Western Minerals Group through Rare Earth Extraction Co Ltd expects to resume rare-earth oxide production at its 74%-owned Steenkampskraal mine from 2013. In January 2013, NI 43-101 indicated resources totaled 32,000 t TREO with 8% heavy REO, and 42,100 t TREO inferred resources. The updated figures included 176,000 t monazite as indicated and 278,000 t inferred resources. Thorium will be extracted from the mixed rare-earth chloride concentrate, and stockpiled.
Cummins Range, Kimberley region, Western Australia
This is a deposit of light REE with inferred resource TREO of 85,000 t at 1.74%, uranium content of 0.0145% (600 tU), and 11.2% P2O5 at 1% cut-off. Subject to proving further resources, Navigator Resources Ltd contemplated developing it as a REE mine with uranium by-product. It is similar geologically to Mount Weld, but with greater uranium content. It has 127,000 t TREO inferred resources at 0.5% cut-off.
Teasdale Lake, Elliot Lake, Ontario
Appia Energy reports 3080 tU indicated resources and 7750 tU inferred resources in connection with rare earths.
Olympic Dam, South Australia
BHP Billiton’s large Olympic Dam mining operation accesses a huge orebody, with the world’s largest resources of uranium, though this is only a by-product of copper (along with gold and silver by-products). The orebody also contains some 53 million tonnes of REO (predominantly lanthanum and cerium), though these are sub-economic and there are no plans to extract them even as by-product at present. They remain in the tailings (as at many uranium mines).
Mary Kathleen, Queensland
This was a uranium mine in a rare earth deposit, and from which no rare earths were recovered commercially. It operated 1958-63 and 1975-82. The uranium grade was 0.10-0.15%, the REE grade about 4-5%, and the company initially had great difficulty keeping the REE assay in product below specified levels of 0.1%. The REOs ended up in tailings.
Wikipedia, Rare Earth Element, accessed 26/4/2011
Greenland Minerals & Energy, http://www.ggg.gl/docs/ASX-announcements/GMEL_Company_Presentation_February_2014.pdf
Pele Mountain Resources
Australia's Identified Mineral Resources 2011, Geoscience Australia