23 February 2012
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Greenland Minerals and Energy Limited (“GMEL” or “the Company”) is pleased to provide an update on metallurgical developments that continue to enhance the Kvanefjeld multi-element project (rare earth elements, uranium, zinc). Kvanefjeld is recognised as one of the world’s largest resources of rare earth elements and uranium, and is favourably located near existing infrastructure in southern Greenland.
In June 2011, GMEL announced that it had identified a means to effectively beneficiate the Kvanefjeld REE-U mineralisation utilising froth flotation. This method was then piloted successfully under continuous operation to produce bulk mineral concentrates (announced October, 2011). Hydro-metallurgical leach studies on the mineral concentrates have now been completed.
Greenland Minerals and Energy Limited (‘GMEL’ or ‘the Company’) has been advancing the Kvanefjeld project, located favourably in southern Greenland, since 2007. A large, outcropping multi-element resource of REEs, uranium and zinc has been defined at Kvanefjeld, with attention now focused on delineating resources at the high-grade satellite deposits Zones 2 and 3.
In parallel with resource development, the Company has been conducting comprehensive metallurgical and process development studies to optimise the Kvanefjeld processing route. A base-case flow sheet was established, as outlined in the Interim Pre-Feasibility Report on Kvanefjeld, released to the ASX in January 2010. The study drew upon extensive historical metallurgical studies generated by Danish Government research agencies, as well as initial studies conducted by GMEL through 2008 and 2009. The 2010 study clearly demonstrated that Kvanefjeld could be developed as a large-scale, long-life and cost effective producer of uranium and rare earth concentrates.
Through 2010 and 2011 focused metallurgical studies continued to advance processing alternatives. Breakthroughs in both mineral beneficiation and hydrometallurgical leaching have firmed up multiple flowsheet options, with trade off studies currently underway to establish the most robust scenario.
In 2011 GMEL commenced environmental and social impact assessments on the Kvanefjeld project, following an extensive phase of stakeholder engagement in Greenland. These studies are scheduled for completion in late 2012, and form key components of an exploitation (mining) license application. Infrastructure studies are also well-advanced. Engineering studies and stakeholder workshops have identified potential locations for key infrastructure items including port, processing plant, accommodation village and tailings storage facilities. Mining studies support a conventional open-pit operation, with a low-strip ratio (1:1) over life-of-mine.
LEACHING OF FLOTATION CONCENTRATES
The beneficiation stage was piloted in Q3 2011, and importantly produced bulk mineral concentrates for metallurgical leach studies. These studies have now been completed with very positive results.
Controlled atmospheric leaching of the mineral concentrate in tanks produces extractions of 90-95% for both uranium and heavy REOs; the two main value drivers to the Kvanefjeld project. Light REOs are also recovered, but at a slightly lower level of extraction.
Following leaching, uranium and REOs can be recovered from pregnant leach solutions with commercially proven solvent extraction and ion exchange techniques.
The ability to achieve high extractions of uranium and heavy REOs using conventional acid solutions under atmospheric conditions is another critical breakthrough in establishing a cost-competitive, efficient flowsheet with low-technical risk. The synergies in leaching uranium and heavy REOs with a single leach circuit are anticipated to improve the economic metrics of the project significantly.
ESTABLISHMENT OF AN ENHANCED FLOWSHEET
The beneficiation and leaching developments form the basis of a flowsheet which consists of sequential froth flotation to firstly concentrate sphalerite (zinc sulphide), and then REE-uranium phospho-silicate minerals, which are then leached using conventional acid solutions under atmospheric conditions (Figure 1). This enhanced flowsheet is designed to produce uranium oxide, a heavy rare earth concentrate, light rare earth concentrate, and zinc concentrate (sphalerite). The Company views this scenario as a logical first phase of a staged development program.
The enhanced flowsheet represents an efficient and scalable development option. Its development reflects the ‘mineral-driven’ approach that the Company has taken throughout its metallurgical studies. The beneficiation-step provides a highly effective means of concentrating the dominant REE-uranium mineral group, from which uranium and REEs can then be simply and efficiently leached. The leach solution chemistry allows for the production of both heavy and light REE concentrates.
The Kvanefjeld project offers the potential for multiple product streams and revenue drivers. GMEL is primarily focused on optimising the project towards uranium and heavy REO production, which then provides greater flexibility in the marketing and pricing of light REE products.
Figure 1. A conceptual representation of the enhanced Kvanefjeld process flowsheet. Flotation produces a zinc concentrate, then a uranium- and REE-rich mineral concentrate that is leached using conventional acid solutions under atmospheric conditions. Uranium is recovered by solvent extraction prior to a stage of impurity removal before REOs are recovered. The majority of ore feed (gangue minerals) is stored as untreated flotation tailings, with only a small proportion (economic minerals) treated chemically to leach uranium and REOs.
In contrast to the base-case that featured an alkaline pressure leach circuit (uranium extraction) then an acid leach circuit (REO extraction), the enhanced flowsheet features a single leach circuit to extract both uranium and rare earths. That single leach circuit delivers high extraction rates from the flotation concentrate for both uranium and heavy REEs under atmospheric conditions. The leach circuit will also be of significantly smaller scale than those in the base-case as it will be treating a higher-grade mineral concentrate that represents <15% of the original ore mass.
As part of a staged development program future increases in uranium and rare earth output can be readily achieved through ramping-up mine throughput. This will be facilitated by expansion of the project’s global resource base following the imminent release of initial resource estimates for the Zones 2 and 3 satellite deposits.
The Company is extremely pleased with the technical developments that have been achieved by the in-house process development team in conjunction with external consultants, and is looking forward to finalising the pre-feasibility program in the coming months.
For the complete ASX announcement go to http://www.ggg.gl/docs/ASX-announcements/Technical-Breakthrough-Atmospheric-Leaching.pdf