Test-work confirms high grade product at Kallak
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Beowulf (AIM: BEM; Spotlight: BEO) and its wholly owned Swedish subsidiary Jokkmokk Iron Mines AB ("Jokkmokk Iron") are pleased to provide an update on the metallurgical test-work programme completed for the Kallak or Gállok Iron Ore project ("Kallak" or "the Project").
Highlights
The 2024 metallurgical test-work programme:
- Has demonstrated the ability to produce an exceptionally high-grade, low impurity iron ore concentrate grading over 68% iron content ("Fe") and containing less than 3.7% silica ("SiO2") and <0.23% alumina ("Al2O3"), which in turn can be further upgraded to over 70% Fe containing ~2% SiO2;
- Was completed in preparation for the Kallak Pre-Feasibility Study ("PFS") building on previous extensive programmes completed between 2013 and 2021;
- Included comminution testing, mineralogical studies, Davis tube, magnetic separation and further upgrading test-work;
- Supports the prior assumption that Kallak can produce a highly desirable concentrate suitable for the Green Steel sector; and
- Defines the preliminary processing flowsheet for the Project.
Ed Bowie, Chief Executive Officer of Beowulf, commented:
"The metallurgical test-work has confirmed that Kallak can produce an exceptionally high grade, low impurity concentrate. Furthermore, this concentrate can be upgraded to a grade of over 70% Fe with low levels of silica, a product that would be well suited for use as feedstock for modern, lower-carbon emitting steelmaking practices including the direct reduced iron - electric arc furnace route. The indicative process flowsheet also has a number of significant advantages: utilising conventional technology and only physical separation with no flotation; and producing a single product.
"The results of this test-work have now been passed to our Process Engineers who will design the full Industrial Flowsheet with appropriate equipment sizing. We look forward to providing the market with further updates."
Historical Metallurgical Test-work
In 2013, following a trial mining programme at Kallak where near-surface mineralised material was excavated from a series of trenches, a composite sample of over 60 tonnes was tested by the Finnish Geological Survey (GTK) at their facility in Outokumpu (Finland). The composite sample contained an average of 29.5% Fe and a mix of magnetite to hematite ore in an approximate ratio of 3.4:1.
A conventional magnetite process route was followed consisting of milling and low-intensity magnetic separation ("LIMS") pre-concentration, followed by ball mill re-grinding together with six cleaner LIMS stages to achieve the final magnetite product. This final product had a grade of 69.4% Fe with average silica content of 3.9% and insignificant levels of sulphur and phosphorous, being below 0.01%. Recovery of the magnetite was calculated to be 95%.
Several different flow sheet options were tested for the recovery of hematite with an ultimate product grading 66.6% Fe and containing 3.3% silica, 0.08% phosphorous and less than 0.02% sulphur being generated. The best beneficiation result was achieved using a combination of spiral separators, supported by High-Gradient Magnetic Separators (HGMS), although recovery remained at below 30%.
In 2015 a further test-work programme was initiated to explore the potential of further upgrading Kallak concentrate to produce a product suitable for use in a Direct Reduction Iron ("DRI") facility. Reverse flotation was used and demonstrated the potential to upgrade the magnetite concentrate to best results of up to 71.5% Fe with low silica and alumina at 0.62% SiO2 at 0.10% Al2O3 respectively. Detrimental elements were also demonstrated to be extremely low with <0.02% sulphur, and <0.1% phosphate from all concentrates.
During 2020 and 2021, further analysis of the orebody identified three distinct iron oxide mineralogies: magnetite and hematite as previously identified and a transitional mineral, maghemite. Maghemite has the same chemical formula as hematite (Fe2O3) but retains the same crystal structure as magnetite and is therefore more strongly magnetic than hematite. In addition, further test-work was undertaken on the upgrading of concentrate using a physical process, high frequency oscillating electromagnetism ("LJC Technology"), rather than the chemical reverse flotation described above. This technology has the benefit of not using chemicals and produced an overall product that was comparable with the reverse flotation test-work at a grade of 69.9% Fe.
Following the identification of maghemite, further Davis Tube test-work was undertaken on 106 representative samples during 2021. The Davis Tube methodology is considered an industry-standard technique for assessing the magnetite proportion of a sample. Material is passed through the 'tube' and the strongly magnetic fraction is held by the magnetic field while the weakly magnetic material is washed down the tube. Results for Kallak North indicated a 71% recovery producing a concentrate with 68% Fe which is therefore broadly consistent with previous test-work.
2024 Metallurgical Test-work
The 2024 metallurgical test-work programme comprised mineralogical analysis using TESCAN TIMA to assess particle-by-particle measurement of mineralogy, grind size, liberation, and separation. This mineralogical study supplemented prior QUEMSCAN studies, which do not distinguish iron oxide minerals, and was supported by microscopic investigations. The TIMA liberation data confirmed previous measurements suggesting magnetite and maghemite may be liberated at P(80) 40 microns.
Comminution test-work on representative samples indicated that the crushing characteristics of the ore are relatively soft whilst it is generally relatively hard from an abrasion/ attrition perspective. This suggests that Fully Autogenous Grinding (FAG) or Semi-Autogenous Grinding (SAG) will be appropriate with the data being used to model likely equipment sizing.
Samples from the comminution testing were then combined to form a composite sample with proportions designed to be representative of the Kallak orebody, particularly in the early years of mine life. Wet Low-Intensity Magnetic Separation ("WLIMS") of this composite sample produce a product with a grade of 68.82% Fe, 3.41 % SiO2 and 0.22 % Al2O3, whilst results from the maghemite sample generated a product grading 68.61% Fe, 3.63 % SiO2 and 0.23 % Al2O3.
Both samples could then be further upgraded using the LJC technology to over 70% Fe with close to 2% SiO2, a product deemed to be a suitable DRI feedstock.
Indicative Process Flowsheet
Based on the results of the metallurgical test-work, a conventional magnetite flowsheet is envisaged with a crushing and grinding circuit and series of WLIMS units working in sequence to recover the magnetic magnetite and maghemite fractions. A single concentrate would be produced with a grade of 68.8% Fe which in turn could be further upgraded with the non-chemical LJC Technology to over 70% Fe. Based on the mining rate of 9 million tonnes per year ("Mtpa") of ore as envisaged in the Scoping Study, the preliminary metallurgical modelling suggests that approximately 2.7 Mtpa of 68.8% Fe containing less than 3.7% SiO2 and less than 0.23% Al2O3 would be produced. Further upgrading is anticipated to still produce approximately 2.7 Mtpa of the >70% Fe concentrate containing approximately 2% SiO2.
The LJC Technology has the potential to upgrade this concentrate, although recoveries marginally decline, and there are capital and operating costs associated with its implementation. A trade-off study is therefore being conducted to determine whether the additional price premium for the higher grade material justifies the inclusion of the LJC Technology. This study will be completed within the coming weeks and determine the base case process flowsheet for the forthcoming PFS.
Recoveries from the processing of the hematite ore have historically been low and economically marginal. Further test-work will be required to determine whether this portion of the orebody should be stockpiled for processing at the end of the mine life.
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