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Pine Point Mining confirms positive metallurgical results

Published by
Global Mining Review,

Pine Point Mining Ltd has received positive results from initial independent metallurgical testing of sample material from one of the deposits at the Pine Point project in the Northwest Territories.

This test work was done on a composite sample from four drill holes from the L36 deposit. This deposit is historical and was not included in the recent PEA, and the sample was obtained as part of a confirmation drilling programme intended to bring several historical deposits into the long-term mine plan. The test was important because modern testing by a previous operator focused on high grade material, while the company's recent test was done on a composite sample grading 3.7% zinc and 0.41% lead, which is similar to the overall grade in the Preliminary Economic Assessment (PEA) of the project released earlier this year.

It was the first test of this grade using the dense media separation (DMS) technique followed by conventional flotation on the concentrated feed. The sample was crushed to 0.25 in. The DMS process rejected 53% of the feed mass while recovering 95 and 91% of the lead and zinc, respectively, into flotation feed stream. The flotation process recovered 85% of the lead into a concentrate grading 76.7% lead from the flotation feed. Zinc in the flotation feed was 93% recovered into a concentrate grading 59.5% zinc. Flotation testing consisted of 3 tests with no optimisation, there is considerable potential to increase metal recoveries at lower concentrate grades.

Detailed feasibility-level DMS and flotation recovery testing was performed by a previous operator on higher grade samples, and that work was used as the basis for the PEA.

Importantly, the testing revealed an ore that is relatively soft and coarse-grained, and the above zinc concentrate grade was obtained without regrinding, which was assumed in the PEA. Not having to regrind would lower both capital and operating costs. The next step in the metallurgical testing will be to increase recoveries to concentrate. This will entail investigating DMS responses at different feed sizes and media specific gravities. This will allow appropriate crusher and screen selection. Flotation optimisation will consider the impact of flotation feed grind, regrind and different reagent combinations with the aim to improve overall recoveries.

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