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Tasman Metals Ltd
Symbol TSM
Shares Issued 65,515,266
Close 2014-07-08 C$ 1.04
Market Cap C$ 68,135,877
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Tasman's Norra met tests show 86% REE recovery

2014-07-09 08:55 ET - News Release

Mr. Mark Saxon reports

TASMAN PRECIPITATES HEAVY RARE EARTH ELEMENT CONCENTRATE AND PROVIDES FLOWSHEET DEVELOPMENT UPDATE FOR NORRA KARR PROJECT, SWEDEN

Tasman Metals Ltd. has precipitated a heavy rare earth element-rich concentrate as part of the hydrometallurgical testwork program under way on the 100-per-cent-owned Norra Karr heavy REE project in Sweden. Preparation of this concentrate is the final step in defining the Norra Karr flowsheet, and marks a significant milestone in the company's metallurgical programs. An update on recent beneficiation progress is also provided.

Beneficiation and hydrometallurgy testwork have been completed by various internationally recognized laboratories and delivered data of a quality suitable for the Norra Karr prefeasibility study, which remains in progress.

Norra Karr is one of the most significant heavy REE deposits in the world, with a simple and predictable REE mineralogy. Previous testwork has shown that the only REE-bearing mineral with significant abundance at Norra Karr is the zirconosilicate eudialyte. Eudialyte is weakly magnetic (paramagnetic) and dissolves rapidly in weak acid at low temperature. This simplicity has allowed for an uncomplicated flowsheet to be developed, that can be achieved with standard mining/processing equipment and widely available chemicals.

Highlights:

  • Crushing and grinding characteristics of the Norra Karr mineralized material are now known. A grind size of 60 microns has been chosen which provides adequate liberation of the REE-bearing mineral (eudialyte) that can easily be achieved through standard commercial equipment.
  • Extensive testwork and optimization of single-stage magnetic separation have been completed by equipment manufacturer Metso Minerals and metallurgical laboratories of the Geological Survey of Finland. This optimization has increased REE recovery in beneficiation to in excess of 86 per cent in less than 35 per cent of the original mass, such that flotation is no longer deemed necessary as was envisaged under the Norra Karr preliminary economic assessment published June, 2013. Magnetic separation shall use standard commercial equipment and does not require process chemicals.
  • Extensive hydrometallurgical research has been completed by ANSTO Minerals which has tested/optimized a process of sulphuric acid leaching, leach solution purification, REE solvent extraction and precipitation of an REE-concentrate. Sulphuric acid was chosen due to its relatively low cost, and its widespread availability in Sweden. A railway line which passes only 25 kilometres from Norra Karr already transports bulk sulphuric acid.
  • Under the hydrometallurgical process developed, leaching is undertaken at ambient temperature and pressure. High-temperature roasting is not required to dissolve eudialyte.
  • The improved magnetic separation has significantly reduced the amount of sulphuric-acid-consuming gangue minerals within the eudialyte-rich mineral concentrate. As a result, sulphuric acid consumption per tonne of ore has fallen to 85 kilograms per tonne from the 150 kilograms per tonne envisaged in the PEA.
  • A heavy REE-enriched oxalate has been precipitated by ANSTO during continuous testing with a grade of approximately 45 per cent REE. The high-value heavy REE dysprosium contributes 4.8 per cent of the REE content. This oxalate can be easily calcined to a high-grade REE oxide subject to customer requirements.
  • Despite Norra Karr being a high-grade zirconium and hafnium deposit, under the metallurgical process being modeled for the PFS, the recovery of Zr is not being considered. Zr shall pass with Hf and niobium to a byproduct that shall be stockpiled for potential future recovery;

"Tasman staff and their consultants have worked hard to optimize the processing conditions for the Norra Karr deposit for our prefeasibility study," said Mark Saxon, Tasman's president and chief executive officer. "We have extensively tested our metallurgical process and have achieved the significant milestone of precipitating an attractive high-purity heavy REE product. Eudialyte was once believed to be a difficult mineral to process, but due to the excellent work by Tasman's team, robust process pathways are now available. We congratulate our team on the milestones they have achieved and are proud to have taken the project from discovery to this significant milestone."

With the guidance of Tasman's PFS consultants, samples used in testwork were carefully chosen from drill core to be representative of the Norra Karr deposit, both in grade and ore type distribution. A five-tonne sample was homogenized then crushed and ground to the target P80 size at a facility in Germany. This bulk sample has a total rare earth oxide grade of 0.61 per cent and has provided a consistent material source for all testing. Where possible, registered REE standards have been inserted to ensure assay quality, and mass balance calculations have consistently been completed to confirm results.

Magnetic separation tests

Due to the paramagnetic nature of eudialyte, magnetic separation has been the focus for beneficiation research. Following multilaboratory testing of magnetic separation equipment, the Metso Minerals continuous HGMS was chosen as most promising for optimization. Metso has worked with the metallurgical division of the Geological Survey of Finland to undertake both batch and continuous testing under a wide range of operating parameters (flow velocity, magnetic field strength, load density, grind size). The optimum operating conditions have been determined, which have been applied repeatedly under continuous tests, the results being both stable and predictable.

Recovery in single-pass magnetic separation consistently exceeded 86-per-cent recovery in 35 per cent of the original mass. Size-by-size assaying and mineral liberation analysis have demonstrated that approximately 70 per cent of the 14 per cent REE lost to the tailings stream is in the fine-grained (below 20 microns) fraction, which should be recoverable by a combination of hydrocyclone separation to recover the fine particles and small volume magnetic separation scavenging step.

Mineralogy of the mineral concentrate from the HGMS predominantly comprises the paramagnetic minerals eudialyte (16.0 per cent) and aegirine (56.9 per cent), with minor contribution of the felsic minerals feldspar (11.1 per cent), nepheline (6.0 per cent) and zeolite (4.9 per cent). The very low content of nepheline and zeolite in this mineral concentrate is significant, as both minerals are soluble in sulphuric acid and therefore increase acid consumption.

Hydrometallurgy tests

ANSTO Minerals in Australia was engaged by Tasman in 2013 to optimize and finalize the Norra Karr hydrometallurgical flowsheet that had been initiated by other parties. ANSTO is an acknowledged world leader in REE hydrometallurgy, and was chosen due to its experience in similar projects. Work was initiated on a poorer-quality mineral concentrate, but moved to the higher-quality material described above in 2014.

ANSTO's work has defined a stable and repeatable hydrometallurgical process that has been applied in continuous operation through to precipitation of an REE oxalate. ANSTO's extensive experience with silica management has allowed for any process-related issues to be quickly resolved.

In previous testwork, various acids were trialled, each giving certain process benefits. ANSTO has used only sulphuric acid for leaching due to its low cost, and widespread availability in Sweden. A railway line which passes only 25 kilometres from Norra Karr already transports bulk sulphuric acid that is produced in copper smelting in Sweden and Finland.

Due to the improved mineral concentrate and ANSTO's superior process control, sulphuric acid consumption (including residual acid) in leaching has been reduced to 85 kilograms per tonne of ore. This is a very significant reduction, as PEA financial modelling indicates sulphuric acid is the single largest processing cost.

Following leaching, purification of the leach solution via chemical and pH control was completed to remove various impurities including silica, iron and manganese. The concentration of REEs in solution was increased using conventional solvent extraction, which were then precipitated in oxalate form through the addition of oxalic acid. The composition of this REE oxalate is provided in the table. This oxalate is strongly enriched in the high-value heavy REEs, which contribute 44 per cent of the material.

The recovery of REEs achieved in the hydrometallurgy stage (leaching to precipitation) is approximately 90 per cent, with heavy REE (not including yttrium) recovery consistently exceeding light REE recovery.

"The results described above come at an important stage of the development of Norra Karr, and will be incorporated into the PFS models," said Mr. Saxon. "Norra Karr is unusual in its heavy REE enrichment, and furthermore has the unique advantage of lying within a First World mining-friendly country with easy access to road, rail, power, process chemicals, skilled labour and the large European market."

                       COMPOSITION OF REE OXALATE
           Weight % REE in
Element      oxalate solid         REO as % of TREO              

Light REE
La                    4.94                    10.7          
Ce                   10.75                    23.2                    
Pr                    1.46                     3.1                     
Nd                    6.76                    14.5                    
Sm                    1.65                     3.5                     
Heavy REE
Eu                    0.27                     0.6            
Gd                    1.66                     3.5                     
Tb                    0.35                     0.7                     
Dy                    2.19                     4.6                     
Ho                    0.49                     1.0                     
Er                    1.29                     2.7                     
Tm                    0.18                     0.4                     
Yb                    1.14                     2.4                     
Lu                    0.15                     0.3                     
Y                    12.21                    28.6  
                     -----                    ----
Total REE            45.48                     100
Light REE %                                   55.1                    
Heavy REE %                                   44.9                    

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, and is secured to Tasman with a 25-year mining lease. The short time taken from discovery to mining lease granting 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 employees, minimizing the need for off-site infrastructure to be built by the company.

Tasman's qualified person, Mark Saxon, fellow of the Australasian Institute of Mining and Metallurgy, and member of the Australian Institute of Geoscientists, has reviewed and verified the contents of this news release.

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