Namibia Critical Metals has provided an update on the development of the Lofdal Heavy Rare Earth project since granting of the Mining Licence in July this year.
The Lofdal Heavy Rare Earth Deposit is one of only two primary xenotime projects under development in the world. The deposit has the potential for significant production of dysprosium and terbium, the two most valuable heavy rare earth elements used in high powered magnets and other high-tech applications.
The Project is being developed in joint venture with Japan Oil, Gas and Metals National Corporation (JOGMEC) targeting a long term, sustainable supply of heavy rare earths to Japan.
The Company has successfully completed hydrometallurgical test work to develop a flowsheet capable of producing a high-grade rare-earth oxide product from a xenotime flotation concentrate.
The Company’s lead metallurgical consultants at SGS Minerals Services Canada (SGS) have simplified the final process stage with an acid bake to crack the mineral xenotime, to purify the pregnant leach solution and to precipitate a rare earth oxalate, which is subsequently calcined to form a product containing >98% total rare earth oxides (TREO).
The acid bake process and concurrent removal of impurities is highly efficient and resulted in a 95% recovery of Dysprosium and Terbium in the leaching operation of the processing flow sheet. The high-quality product is practically free of typical deleterious elements like thorium and uranium (<3 ppm combined U+Th).
Darrin Campbell, President of Namibia Critical Metals stated:
“These very positive test results are another big milestone for the Lofdal project and show that we are on the right path towards establishing that Lofdal can produce a valuable heavy rare earth product.
“This will allow us to advance an updated assessment of large-scale and integrated rare earth production towards a high purity Rare Earth Oxide product in Namibia. This would result in further value addition in Namibia and puts the country on the global map of rare earth supply strategies.”
Hydrometallurgical test work and results
Two flotation concentrates produced by processing of bulk samples from the Lofdal deposit were tested at the laboratories of SGS in Lakefield, Ontario, to determine the potential for producing a marketable rare earth product with minimal impurities. Previous hydrometallurgical test work had focused on more costly caustic cracking following gangue acid leach.
The comprehensive test work at SGS has demonstrated the acid bake route is preferred due to lower reagent costs and higher recovery of the heavy rare earths.
A total of 12 acid bake and water leach tests were completed throughout the test program to investigate the dissolution of rare earth elements (REE) and the behaviour of gangue minerals through the addition of sulphuric acid at elevated temperatures (200-300°C).
Optimum results were achieved using an acid addition of 1250 kg/t H2SO4 at 300°C followed by a water leach at 20% solids by weight at 25°C. Under these conditions, the tests showed very good REE recoveries with 97-98% for yttrium, 95% for dysprosium and 94-95% for terbium.