Tasman Metals (CVE:TSM) (AMEX:TAS) said Thursday morning that it has made "signficant progress" in the development of a processing flow sheet for its Norra Karr heavy rare earth element (REE) and zirconium project in southern Sweden.
The "metallurgical breakthrough", as the Canadian mineral exploration company calls it, includes the preparation of a mineral concentrate with high REE recovery, using wet magnetic separation, and the successful use of flotation to further upgrade the mineral concentrate.
Tasman said high recoveries and low sulphuric acid consumption was achieved when leaching the mineral concentrate in an "ambient temperature" and atommospheric pressure environment.
The processing flow sheet is as a result now well-defined for inclusion in the preliminary economic assessment (PEA) for the project, which is nearing completion by Pincock, Allen & Holt, the miner said.
In addition, Tasman said that potentially saleable nepheline/feldspar co-product, with low iron content, was separated during physical concentrate preparation.
"The metallurgical team at the Geological Survey of Finland has made great progress for Tasman in developing a simple and potentially low cost processing method for Norra Karr" said the company's president and CEO, Mark Saxon.
"The mineral concentrate we have prepared by magnetic separation and flotation is as encouraging as we hoped for at the start of our research.
"In addition to achieving high REE recoveries, we have now also separated a potentially saleable nepheline/feldspar co-product, which may allow Tasman to significantly reduce tailings dam requirements, and optimally use the mined resource."
Saxon continued to say that the acid leaching program was also a "success", with sulphuric acid consumption sharply reduced when compared to previous tests, and recoveries of the high value heavy rare earth elements exceeding 90 percent. Also, no roasting or elevated pressure was required.
The mineral processing division of the Geological Survey of Finland (GTK) in Outokumpu was hired in 2011 to undertake physical concentrate preparation and leaching testing on a sample of Norra Karr mineralization.
Approximately 100 kilograms of representative uncrushed drill core was delivered to GTK.
Tasman said that previous metallurgical work identified a simple leach process for the project, therefore GTK focused a majority of its research on beneficiation.
Within beneficiation testing, a total of 26 magnetic separation and flotation tests were run by GTK. By magnetic separation alone, results were "very encouraging", the company said, with 95.1 percent REE recovery into 55 percent of the mineral mass, 94.1 percent REE recovery into 49 percent of the mineral mass, and 88.0 percent REE recovery into 47 percent of the mineral mass.
Zirconium recovery was typically in the range of 50 to 60 percent, as some of the zirconium-bearing mineral, catapleiite, reported to the non-magnetic fraction, Tasman explained, which is largely comprised of the felsic minerals including nepheline, feldspar and natrolite.
The non-magnetic fraction is low in iron, with a similar chemistry and mineralogy to material used in large volume in Europe within the glass and ceramic industries. Tests for whiteness, translucency and melting point of this co-product are now being run, the company said.
Combined magnetic separation and flotation tests yielded REE recovery rates of 86.6 percent into 37.6 percent of the mineral mass, and 84.1 percent into 26.5 percent of the mineral mass.
Meanwhile, leach tests were also completed by GTK on the mineral concentrates in the beneficiation process, which were focused on minimizing acid and energy requirements during processing. Results yielded 95 percent recovery of the heavy REE yttrium, 88.5 percent of light REEs lanthanum and cerium, and 82 percent of zirconium.
According to Technology Metals Research, Norra Karr is unusually enriched in the high value heavy rare earth oxides when compared to other peer projects, with heavy rare earth oxides (HREO) as a percentage of total rare earth oxides (TREO) exceeding 50 percent.
Of particular note are the high grades of yttrium oxide, dysprosium oxide and terbium oxide, metals with strong demand in the lighting and automotive industries, and with few potential sources outside China.
The research firm also rates Norra Karr as the fourth largest heavy rare earth project in the western world by contained metal.
Studies have shown the host rock at the project to have a simple mineralogy, with almost all rare earth elements contained within the acid-soluble mineral eudialyte. Eudialyte comprised 7.2 percent of the sample delivered to GTK.
Mineralization at Norra Karr occurs within the peralkaline nepheline syenite intrusion, which covers an area of 350 by 1100 metres, first discovered in 1906.
The asset is located in southern Sweden, 300 kilometres southwest of the capital Stockholm and lies in mixed farming and forestry land. The site is well serviced by power, roads and water, allowing all year round access, the company said.
In December, Tasman reported final drill results from the phase three drill program at the project, including a new REE-zirconium intrusion located five kilometres south of the property.
Notable results from the 29-hole program, each of which hit mineralization, included hole NKA11042, which intersected 126.0 metres grading 0.48 percent TREO and 1.63 percent zirconium, including 0.8 percent TREO and 1.77 percent zirconium over 36.3 metres.
The demand for rare earth elements, like those at Norra Karr, is increasing, due to the metals unique properties that make them essential for high tech and environmentally-friendly applications, ranging from iPads to hybrid cars.
Since over 95 percent of REE supply is sourced from China, the European Union is supporting policy to ensure domestic supply of the metals.