Highlights:
- Flowsheet improvements yield recovery gains and enhanced magnetite concentrate quality (all figures below relative to Preliminary Economic Assessment ("PEA") model)
- Nickel recovery of 62% – 10 percentage points or 19% improvement
- Iron recovery of 45% - 2 percentage points or 5% improvement
- Magnetite concentrate grade of 54% iron – 6.5 percentage points or 14% improvement
- Cobalt recovery of 70% - 30 percentage points or 75% improvement
A key focus of the feasibility study activities is the continued improvement in flowsheet performance given its potential to add significant value to the project, particularly as less than one year of work had been completed on the project before results of the PEA were announced on
The locked cycle test ("LCT") conducted at XPS Expert Process Solutions, a
The flowsheet utilized in this test included changes to reagents, grind sizes, and position of magnetic separation in the flowsheet. No further details are being provided at this time as the Company believes these improvements are a proprietary competitive advantage.
Table 1 – Locked Cycle Test - Summary of Results Compared to the PEA Model
LCT Recovery (%) | LCT Concentrate Grades (%) | |||||||||
Nickel Concentrate | Magnetite | |||||||||
Ni | Co | Fe | Cr | Ni | Co | Fe | Fe | Cr | ||
Actual | 62 | 70 | 45 | 21 | 13 | 0.9 | 39 | 54 | 4.5 | |
Modelled | 52 | 40 | 43 | 27 | 12 | - | - | 47.5 | 3.3 | |
Difference | +10% | +30% | +2% | -6% | +1% | - | - | +6.5% | +1.2% |
As expected, 100% of the nickel recovery in the flotation concentrate reported to the Standard Concentrate product because pentlandite was the primary nickel sulfide mineral in this sample. The nickel concentrate grade of 13% is 1% higher than our target 12% grade for this product and the cobalt grade was 0.9% (no target in PEA). The iron and MgO content of the flotation concentrate was 39% and 7% respectively. PGM assays are pending. The iron content of the flotation concentrate represented 11 percentage points of the 45% overall iron recovery and 1 percentage point of the overall 21% chromium recovery.
Table 2 – Locked Cycle Test – Magnetite Concentrate Quality
LCT Magnetite Concentrate Grades (%) | |||||
Fe | Cr | Ni | MgO | Co | S |
54 | 4.5 | 0.13 | 10 | 0.008 | 0.15 |
The iron grade of 54% is a substantial improvement over the modelled grade of the 47.5% iron utilized in the PEA. The chromium grade of 4.5% is higher than the 3.3% chromium grade that was modelled in the PEA and the chromium recovery of 21% was lower than target recovery in the PEA of 27%. Of the nickel recovery, 1% was reported to the magnetite concentrate. Given the nickel and chromium content of this magnetite concentrate, it is expected to be utilized in the production of stainless steel and other alloys where the nickel and chromium are a valuable feed.
As cobalt was not a payable metal in the PEA, it was not a priority during the PEA flowsheet development and optimization work. As it is expected to be a payable metal in the feasibility study, improvements in cobalt recovery are also a key focus of flowsheet development. Cobalt recovery was materially improved to 70% (versus of an expected target of 40% in the PEA) to the nickel concentrate which graded 0.9% cobalt.
Before completing the LCT, flowsheet improvements were first demonstrated in open circuit tests on a range of samples from across Crawford with head grades between 0.30 – 0.43% Ni and range of mineral compositions. The open circuit tests demonstrated an increase of at least 6 percentage points in nickel recovery and average increases in nickel and cobalt recoveries to the flotation concentrates of 9% and 17% respectively (See Table 3 and Figure 1 below). This result does not include the contribution of nickel from the magnetite concentrate, as this circuit was still under development during some of these tests. For three out of the four samples, modelled nickel recovery was achieved in the flotation circuit alone without any contribution from the magnetite concentrate.
Table 3 – Open Circuit Tests – Comparison of New Flowsheet versus PEA Flowsheet
Summary of Flotation Recovery for Nickel and Cobalt
Ore | Head Grade | Nickel Flotation Recovery | Cobalt Flotation Recovery | |||||||
Ni | S | S/Ni | Before | After | Diff. | Before | After | Diff. | ||
Sample 1 | HGC | 0.30 | 0.11 | 0.37 | 26 | 42 | + 16 | 30 | 60 | + 30 |
LCT Sample | HGC | 0.31 | 0.30 | 0.97 | 53 | 60 | + 7 | 62 | 80 | + 18 |
Sample 3 | HGC | 0.38 | 0.25 | 0.66 | 46 | 52 | + 6 | 51 | 60 | + 9 |
Sample 4 | HGC | 0.43 | 0.26 | 0.60 | 56 | 62 | + 6 | 41 | 53 | + 12 |
Average | + 9 | Average | + 17 |
For further details, including key assumptions, parameters and methods used to estimate the results of the PEA, and data verification, please refer the "Crawford Nickel-Sulphide Project National Instrument 43-101 Technical Report and Preliminary Economic Assessment", with an Effective Date of
Next Steps in
Metallurgical test work through the remainder of 2021 will focus on finalizing a flowsheet for the Feasibility Study which is expected to be completed in 2022.
The Company will continue the flowsheet development work through the balance of the year and is continuing to target improvements in both recovery and quality of the concentrates.
Nickel recovery from the slimes circuit was not included in the reported results and represents a further opportunity to improve flowsheet performance. The nickel recovery in the slimes concentrate was 3.4% with a corresponding grade of 3.3% Ni. This stream has the potential be in combined into the main flotation circuit and be upgraded to further increase nickel recovery.
Qualified Person and Data Verification
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Cautionary Statement Concerning Forward Looking Statements
This press release contains certain information that may constitute "forward-looking information" under applicable Canadian securities legislation. Forward looking information includes, but is not limited to, the metallurgical results, the timing and results of the feasibility study, the results of Crawford's PEA, including statements relating to net present value, future production, estimates of cash cost, proposed mining plans and methods, mine life estimates, cash flow forecasts, metal recoveries, estimates of capital and operating costs, timing for permitting and environmental assessments, realization of mineral resource estimates, capital and operating cost estimates, project and life of mine estimates, ability to obtain permitting by the time targeted, size and ranking of project upon achieving production, economic return estimates, the timing and amount of estimated future production and capital, operating and exploration expenditures and potential upside and alternatives. Readers should not place undue reliance on forward-looking statements.
Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of
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