Greenland Minerals and Energy says it is close to completing the development of a beneficiation process to produce a high grade material concentrate which provides cost advantages for the Kvanefjeld multi-element project in Greenland. Beneficiation development began in September 2010 and has resulted in a “well-tested process utilising commercially established froth flotation.” The company says this is likely to result in “substantial reductions to both the capital and operating costs of the project by treating a high grade mineral concentrate rather than whole of ore.”
The flotation process is able to concentrate 82% of the rare earth elements in 8.5% (mass pull) of the original ore mass, with the economic optimum for the Kvanefjeld project estimated within a mass pull range of 8 to 10%. This effectively increases the in-ground ore grade from notionally 1.2% rare earth oxides (REO) to 12% REO in concentrate. In addition to concentrating the rare earth elements, uranium is concentrated at a grade of about 0.2%. The favourable mineralogy of the Kvanefjeld project presents a major advantage in that it can be beneficiated effectively, and is amenable to leaching under atmospheric conditions without costly high temperature mineral cracking. The ores allow for a grind size of 75 to 100 microns (80% passing size) to be used with no de-sliming required. The company states that the design for the Kvanefjeld flotation circuit is simple relative to base metal flotation and flotation circuits of other rare earth projects, with a small number of stages required.
Processing of the ores requires two main steps - beneficiation followed by hydrometallurgical leaching, both of which have been evaluated at the project in Greenland. While the beneficiation step must take place in close proximity to the ore deposits, the substantial grade increase and mass reduction achieved through beneficiation presents Greenland Minerals and Energy with the option to ship the concentrates to carry out leaching outside of Greenland. Initial studies to evaluate the transport costs of the concentrates indicate that is represents about 5% of the contained value, which is in line with the transport costs of base metal flotation concentrates that are commonly shipped elsewhere for refining. The company is therefore currently investigating the benefits of establishing a hydrometallurgical refinery closer to markets in a lower cost environment. This option also provides greater flexibility in structuring development and investment scenarios with strategic partners.
A recent pre-feasibility study identified the potential for Kvanefjeld to be developed as a long-life, cost effective producer of heavy, light and mixed rare earth concentrates, uranium oxide and zinc. Kvanefjeld will be able to generate four main products including a high grade zinc sulphide concentrate. The development scenario from an annual 7.2 Mt throughput would provide 2.6 Mlb of uranium oxide, 4,200 t of heavy rare earth hydroxide, 10,400 t of mixed rare earth carbonate and 26,200 t of light rare earth carbonate.
