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Tasman Metals Ltd
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Close 2012-11-08 C$ 1.40
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Tasman Metals recovers up to 76.9% TREO at Norra Karr

2012-11-08 09:48 ET - News Release

Mr. Mark Saxon reports

TASMAN ADVANCES MINERAL PROCESSING AT NORRA KARR, SWEDEN

Tasman Metals Ltd. has provided an update on recent process optimization results from expanded metallurgical testing at the company's 100-per-cent-owned Norra Karr heavy rare earth element/zirconium project in Sweden. Test work was completed in Germany by Anzaplan (Dorfner Analysenzentrum und Anlagenplanungsgesellschaft mbH), a member of the Dorfner group of companies, Germany's leading supplier of industrial minerals.

Highlights

  • High recovery of rare earth elements in a low mass during combined flotation/magnetic separation tests, including 82.5 per cent yttrium oxide (Y2O3) and 76.9 per cent total rare earth oxide (TREO) recovered in only 25.2 per cent of the original mass;
  • High recovery of rare earth elements in magnetic separation tests on three major ore types from Norra Karr;
  • Eudialyte confirmed as the only rare-earth-element-bearing mineral present in more than trace abundance in all ore types;
  • All major ore types shown to be mineralogically indistinguishable when ground to 500 microns, suggesting geological variation across the orebody is unlikely to affect processing behaviour;
  • Flotation test work very successful in separating aegirine from eudialyte using commercial reagent;
  • Low-iron nepheline/feldspar fraction identified as potential byproduct.

Mark Saxon, president and chief executive officer, stated: "The effectiveness of the current optimization tests for combined magnetic and flotation techniques by Anzaplan give us confidence that further research will enable a high-recovery/low-mass mineral concentrate to be produced from Norra Karr ore. Our metallurgical research is a continuous process, with facilities in Europe and North America working to further optimize the flow sheet. Data generated by Anzaplan will be a key part of our upcoming prefeasibility study and pilot plant tests."

Three bulk samples totalling approximately 1.2 tonnes were supplied to Anzaplan, representing the two major (pegmatitic grennaite and migmatitic grennite) and one minor ore type (grennaite) that comprise the Norra Karr resource. Each sample was composited from drill core collected across the deposit and is considered very representative. All previous metallurgical testing was performed on blended material combining all ore types. Mineralogical character and metallurgical behaviour of each ore type were tested to constrain future processing considerations. Geochemical character of each ore type based on drilling information is shown in the attached table.

      SUMMARY OF PRINCIPAL ORE TYPE GEOCHEMISTRY FROM AVERAGE DRILLING DATA

                               TREO   HREO/TREO    ZrO2  Dy2O3     Y2O3  Tb2O3     Nd2O3 
                                 (%)         (%)     (%)  (ppm)    (ppm)  (ppm)     (ppm)

PGT (pegmatitic grennaite)    0.614        54.7    2.00    289     2300     42       662   
GTM (migmatitic grennite)     0.490        45.0    1.52    184     1506     27       563   
GTC (grennaite)               0.261       63.5     1.33    152     1056     20       233   

- TREO (total rare earth oxide) refers to the sum of La2O3, Ce2O3, Pr2O3, Nd2O3, 
  Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3 and Y2O3.
- HREO (heavy rare earth oxide) refers to sum of Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3,
  Er2O3, Tm2O3, Yb2O3, Lu2O3 and Y2O3. 
- The most significant rare earth oxides by percentage are Y2O3, La2O3, Ce2O3,
  Nd2O3 and Dy2O3.

Mineralogy

Mineral liberation analysis (MLA) was completed on 15 samples to identify mineralogy and liberation trends at a range of grain sizes. MLA demonstrated that once crushed to 500 microns (0.5 millimetre) or less, based on the range and relative distribution of minerals present, all three ore types are indistinguishable. The principal rare-earth-element-bearing mineral at Norra Karr is eudialyte in all ore types, which has a modal abundance of 7.8 per cent and 6.7 per cent in the major ore types pegmatitic grennaite and migmatitic grennite, respectively. This simplicity and homogeneity of ore is very encouraging, suggesting geological variation is unlikely to significantly influence metallurgical processing.

Consistent with previous research is the very low abundance of unidentified other minerals, at 2.4 per cent or less, in all three ore types. While most REE projects display a complex range of REE-bearing minerals, rare earth elements at Norra Karr are virtually entirely hosted by eudialyte, minimizing complexity in the processing flow sheet.

As eudialyte is soft relative to other mineral phases in the rock; MLA also highlighted that it reports with greater abundance in the finer grind fractions. The additional sample from Norra Karr is now with grinding equipment suppliers to test and optimize sizing behaviour under various grind conditions.

Mineral concentrate tests

A range of mineral concentrate preparation tests were run by Anzaplan, based on the previously reported results achieved by the Geological Survey of Finland (GTK) in 2011. The aim was to produce a mineral concentrate containing most or all of the eudialyte (so achieving high recovery), while discarding most of the unmineralized gangue material (so achieving low sample mass). Tests were run in parallel on the different ore types; however, no significant variation in results by ore type were observed. While magnetic separation and flotation were the focus of research, gravity, electrostatic and centrifuge methods were also applied, each of which achieved only poor eudialyte separation.

Magnetic separation

Due to the paramagnetic behaviour of eudialyte, magnetic separation performed very well under non-optimized conditions. Numerous tests were completed, which demonstrated the excellent magnetic extractability of both eudialyte and a common iron-bearing mineral aegirine. Review of external publications suggest aegirine is not soluble under the acid conditions considered for hydrometallurgical processing of Norra Karr ore, and shall therefore be inert in a rare earth element leach circuit. Example recoveries achieved with single pass (not recirculated) WHIMS (wet, high-intensity magnetic separation) using the minus-100-micron fraction of representative Nora Karr ore are shown in the attached table.

Tasman is now focused on further improving the eudialyte concentrate quality by multiple-stage magnetic separation and regrinding methods that were successfully tested by GTK in earlier bench-scale tests.

         RECOVERY ASSOCIATED WITH MAGNETIC SEPARATION 

                                      TREO       ZrO2       Fe2O3
                            Mass  recovery   recovery    recovery
Minus-100-/
plus-20-micron 
fraction                     53%       97%        71%         99%     
Minus-20 micron 
fraction                     23%       80%        41%         91%     

Flotation

Extensive flotation testing was also completed by Anzaplan. While eudialyte does not appear amenable to efficient direct flotation, a commercially available flotation reagent at near-neutral pH was shown to be extremely effective in the selective removal of aegirine from eudialyte.

Aegirine is three times more abundant than eudialyte in typical ore samples; therefore, its removal greatly reduces the mass of the magnetic fraction. Non-optimized test results indicate that approximately two-thirds of the aegirine can be removed from the crushed sample prior to magnetic separation at a TREO recovery of 88 per cent. Removal of this material prior to magnetic separation significantly improves quality of the eudialyte concentrate, with only a small loss of REE.

Combined flotation and magnetic separation

Furthermore, Anzaplan has tested various scenarios combining flotation and magnetic separation. One such combination proved extremely effective, where recovery for the total process was 82.2 per cent of the yttrium oxide, 76.9 per cent of the TREO and 49.7 per cent ZrO2 in only 25.2 per cent of the mineral mass. Recovery of other heavy REEs (Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) mirrors the recovery of Y2O3 in flotation and magnetic separation tests.

The relationship between flotation and magnetic separation, and the impact on operating and capital costs is now the subject of continuing research. A concentrate sample produced by flotation and magnetic separation has been supplied to a research partner for additional hydrometallurgical leach testing.

Minor research was also carried out by Anzaplan on the byproduct materials. While significant work remains to be undertaken, the feldspar/nepheline product removed as the non-magnetic fraction during magnetic separation has a bulk chemistry and sufficiently low iron content, in line with the requirements of various European glass industries.

Tasman's 100-per-cent-owned Norra Karr project is the only National Instrument 43-101-compliant rare earth element resource in mainland Europe. Norra Karr lies 15 kilometres north-northeast of the township of Granna and 300 kilometres southwest of the capital, Stockholm, in mixed forestry and farming land. The short time taken from discovery to mining lease application demonstrates the efficiency and advantage of operating in a jurisdiction with a strong and transparent mining act and a long-term association with resource industries. The project is proximal to road, rail, power and operating ports, plus skilled personnel, minimizing the need for off-site infrastructure to be built by the company.

Norra Karr is one of the largest and most economically robust projects amongst its peers, due to the high contribution of the high-value critical rare earth elements (dysprosium, yttrium, neodymium and terbium). Substantial capital and operating cost benefits are provided by the existing infrastructure and the simple mineralogy that allows ambient temperature and pressure processing. Norra Karr's proximity and easy road access to European markets stands as a unique operating advantage for the project.

Samples associated with this test work were analyzed at the laboratory of Anzaplan in Hirschau, Germany, an ISO 9001:2000-accredited facility, where duplicates, repeats, blanks and known standards were inserted according to standard industry practice. Tasman provided registered standards produced from Norra Karr material as further quality assurance/quality control. The qualified person for the company's exploration projects, Mr. Saxon, president and chief executive officer of Tasman, and a member of the Australasian Institute of Mining and Metallurgy and Australian Institute of Geoscientists, has reviewed and verified the contents of this release.

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