TORONTO, ONTARIO April 27, 2009, Noront Resources Ltd. (“Noront” or the “Company”) (TSX Venture: NOT) is pleased to present the results of preliminary metallurgical studies prepared by SGS Lakefield on chromite mineralization from its Blackbird chromite deposits in the Ring of Fire area of northern Ontario located in the James Bay Lowlands. The studies were undertaken to establish the feasibility of extracting marketable products, not only from the high grade massive chromite beds, but also from lower grade zones diluted by intervening beds of silicate rocks containing disseminated chromite.
HIGHLIGHTS of TESTING
- Massive chromite is amenable to dense media separation (DMS) at < 2 mm size fractions. Further testing is planned at the small lump and chip size to confirm that direct shipping ores can be produced by DMS;
- Narrow intercalated chromite beds and heavily disseminated chromite within ultramafic beds can be combined to produce a high quality concentrate using conventional gravity separation;
- Bench-scale gravity concentration tests provide Cr recoveries of 87% on massive chromite, and 80% on a mixture of heavily disseminated chromite and intercalated chromite beds;
- Gravity concentrates grade 51.9 to 53.4% Cr2O3 with Cr:Fe ratios of 2.2 to 2.4 and SiO2 below 3%, suitable as metallurgical concentrate for ferrochrome production;
- The potential for generation of high value-added products such as foundry sands, refractories, or chemical feedstocks by further slightly lowering silica contents to below 1% is being investigated by continued metallurgical test work.
The Blackbird deposit comprises both thick massive beds of chromitite up to several tens of metres thick, and extensive intersections of intercalated chromitite and silicate rocks containing various amounts of disseminated chromite, commonly interbedded on scales of millimetres to metres. The massive chromite beds are of grade and composition comparable to products sold worldwide as direct-shipping lumpy ore (Cr2O3 > 40%, Cr:Fe > 1.8). The intercalated material contains narrow beds of the same material that are too narrow to mine separately and therefore would need to be beneficiated in order to recover economically valuable chromite concentrates.
Noront has identified five grade categories of chromite mineralization:
- MC is massive chromite (> 75modal % chromite) occuring in beds greater than 4 cm true thickness.
- D3 includes heavily disseminated chromite (> 25 modal % chromite) hosted by ultramafic silcate rocks.
- D2 is disseminated chromite (> 15 modal % chromite).
- D1 and D are disseminated chromite with greater than or less than 5% chromite, respectively. Intercalations of sillicates and chromitite beds < 4 cm in true thickness are included in the estimation of modal abundance of the disseminated chromite.
We report here the results obtained on two samples chosen to represent the range of medium (D2, D3) to high-grade (MC) mineralization styles present in the Blackbird deposit. Material was obtained by quarter-sawing previously assayed core. One sample (henceforth referred to as massive) comprises 17 m of NQ quarter core continuously sampled through a single bed of massive chromite between 201 and 228 m in drill hole NOT-08-1G017. Another sample (henceforth referred to as intercalated) consists of 15 m of continously sampled NQ quarter core comprising intercalated chromitite beds and heavily disseminated chromite between 190 and 205 m from drill hole NOT-08-065, as well as two one-metre continuous samples of similar NQ quarter core (215 to 216 m and 220 to 221 m) from the same hole. Only 51% of the intercalated chromitite sample consisted of massive beds; the remainder was interbedded D2 and D3 disseminated (32%) and D+D1 disseminated (16%).
Three types of separation were investigated by SGS Lakefield. Results are summarized in Table 1. After stage crushing to -10 mesh the +20 mesh size fraction (+841 / -2000 μm) was treated with heavy liquids (HLS) to simulate the process of dense media separation (DMS). In the intercalated chromitite sample the recovery in the sink fraction at SG of 3.3 was 88.7% of the Cr content of the initial sample, resulting in an upgrading from 35.1% Cr2O3 to 42.1% Cr2O3. No significant change was observed in the grade of the massive chromite during heavy liquid separation.
Magnetic separation was performed after further pulverizing to -48 mesh on the +200 mesh size fraction (+74 / -300 μm). Low intensity magnetic field was used to remove any magnetite present, followed by a high-intensity step to concentrate the chromite. The intercalated chromitite sample was upgraded from 35.1% to 47.1% Cr2O3 in the high-intensity concentrate while achieving a Cr recovery of 78% and reducing SiO2 contents from 11.4% to 6.32%. The massive chromite sample was upgraded to 50.1% Cr2O3 with Cr recovery of 81.9% in the high-intensity magnetic concentrate. Material lost to fines was not included in the calculation of Cr recoveries; the reported values are taken over the entire size range below 48 mesh.
|Material||Cr2O3 %||Cr %||Fe %||Cr:Fe||SiO2 %||MgO %||Al2O3 %||S %||Cr recovery (%)|
|Intercalated chromite (head)||35.1||24.0||12.0||2.00||11.2||18.8||10.1||0.06||100|
|HLS concentrate (SG > 3.3)||42.1||28.8||12.7||2.27||8.51||16.0||10.8||0.04||88.7|
|high magnetic flux concentrate||47.1||32.2||14.6||2.21||6.32||14.6||10.2||0.01||78.0|
|Massive chromite (head)||43.7||29.9||13.4||2.2||7.3||14.5||12.0||0.02||100|
|HLS concentrate (SG > 3.3)||44.1||30.2||14.0||2.16||7.0||14.7||12.7||0.01||96.5|
|high magnetic flux concentrate||50.1||34.3||14.1||2.43||4.6||12.8||12.6||0.01||83.5|
Table 1. Head grades and concentrate compositions for two samples of chromite mineralization.
Gravity separation was done by stage grinding to -70 mesh (< 212 μm) and passing this material over the Wilfley table and the superpanner. The intercalated chromitite sample produced a gravity concentrate grading 51.9% Cr2O3 and 2.78% SiO2 while providing 80.7% overall Cr recovery. The massive chromite sample produced a gravity concentrate grading 53.4% Cr2O3 and 2.12% SiO2 while achieving 87.6% Cr recovery.
Discussion of results:
Gravity separation was highly successful, producing material equivalent to high quality metallurgical concentrate at 52% Cr2O3, SiO2 below 3%, and a Cr:Fe ratio of 2.2 from intercalated chromitite to 2.4 from massive chromite. Continued testwork will be aimed at the production of clean concentrates with SiO2 below 1% for end-uses such as foundry sands, chemical feedstock, and refractory applications.
The magnetic separation was successful at producing concentrates suitable for pelletizing as a very high quality direct smelter feed in the range from 47 to 50% Cr2O3. However with SiO2 concentrations in the range 4 – 6% these materials cannot be considered metallurgical concentrates. Ongoing test work is aimed at improving the removal of silica.
The heavy liquid separation was intended to be a diagnostic tool to demonstrate the feasibility of sorting massive chromite from disseminated material using dense media. In this regard it was successful, since the particles being separated in this manner are small rock chips comprising many grains of chromite and gangue. The procedure therefore demonstrates clearly that waste can be separated from potential ore using dense media. However the grain size employed was finer than would normally be used in mine-scale DMS plants and therefore the results should be taken only as encouragement that massive material can be sunk to separate it from finely intercalated and disseminated materials requiring further concentration by magnetic or gravity separation. Further work is planned to determine the DMS recoveries of direct shipping massive chromite ore achievable at the chip (+1 / -6 mm), small lump (+6 / -25 mm), and lump size range (+15 / -80 mm).
The Blackbird deposit contains, in addition to extensive massive beds of chromitite, very large volumes of intercalated thin chromitite beds and weakly to strongly disseminated chromite. The dilulted grades estimated by averaging the intercalated beds appear to be low, and show Cr:Fe ratios that are affected by the presence of iron-rich silicate gangue within the diluted average grades. The present test results demonstrate unequivocally that high grade products can be generated from both kinds of mineralization using conventional low-cost methods of DMS and gravity separation, and show that the Cr2O3 and Cr:Fe content of the extractable chromite is much higher than would be suggested by the diluted values reported over low-grade intersections.
Joseph Hamilton, Co-Chief Executive Officer states that “These metallurgical results are an excellent preliminary start, demonstrating that Noront’s chromite discoveries not only have the potential to be world class, but are high grade and of desirable quality, giving Noront the flexibility to produce a range of chromite materials for a wide variety of end-users. We look forward to finalizing our metallurgical testing.”
This press release has been reviewed and approved for dissemination by Noront’s senior management including John Harvey, P.Eng. Chief Operating Officer, Dr. James Mungall P.Geo., Chief Geologist, and Jim Atkinson, P.Geo. Exploration Manager, all being Qualified Persons under Canadian Securities guidelines.
For further information please contact the Investor Relations Department at (416) 238 7226, firstname.lastname@example.org
ON BEHALF OF THE BOARD OF DIRECTORS:
”Paul A. Parisotto and Joe Hamilton”
Co-Chief Executive Officers