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GMEL looking to simplify refining at Kvanefjeld rare earths project

15th January 2018

By: Megan van Wyngaardt

Creamer Media Contributing Editor Online

     

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JOHANNESBURG (miningweekly.com) – A technical optimisation programme, currently being undertaken at the Kvanefjeld project, in Greenland, has identified significant improvements at the project, Greenland Minerals and Energy (GMEL) reported on Monday.

The optimisation programme, which is being carried out in collaboration with major shareholder Shenghe Resources Holding, is investigating a number of opportunities to simplify the leach process and readdress the reagent strategy.

This aimed to reduce project infrastructure in Greenland, reduce the number of processing steps and equipment sizing, and to best align intermediate product with downstream separation technology. Testwork has been highly successful in validating the enhanced and simplified leaching method, GMEL reported.

MD Dr John Mair commented that the simplified refining circuit would bring numerous benefits to the project. “We draw on guidance from Shenghe to use Kvanefjeld’s unique qualities to establish a highly competitive cost structure and align the project with downstream processing.

“Coupled with major flotation improvements to produce a higher-grade, lower-mass mineral concentrate, the simplified refining circuit will result in smaller equipment sizing and less support infrastructure leading to a reduction of capital and operating costs,” said Mair.

The project enhancements would also reduce the project’s in‐country footprint and impacts, while serving to increase the profitability.

The Kvanefjeld project, 100% owned by GMEL, is underpinned by a Joint Ore Reserve Committee-code compliant resource of just under one-billion tonnes and an ore reserve estimate of 108-million tonnes to sustain an initial 37-year mine life.

It is projected to be one of the largest producers globally of key magnet metals including neodymium, praseodymium, dysprosium and terbium.

PROJECT OPTIMISATION
Key to the revised processing strategy has been the evaluation of hydrochloric acid (HCl) for direct concentrate leaching. This is a departure from the feasibility study process, which uses sulphuric acid for direct leaching and HCI for secondary leaching.

Previous attempts to use direct HCI were met with issues owing to silica contamination. GMEL has now devised a method that allows the silica in the concentrate to be controlled in a single leaching step.

This occurs while still extracting high levels of rare earths and uranium from the concentrate. The new method mixes HCI directly with mineral concentrate to produce a viscous paste. This viscous paste is then mixed for 30 minutes before being dissolved in water (water leach).

In the viscous paste, the rare earths are dissolved and the silica is controlled by precipitation in a favourable form. This method for extracting the rare earths is not dependent on high temperature, high pressure or extreme chemical treatment that is otherwise the norm in rare earth production. The method is applicable owing to the non-refractory nature of the key rare earths mineral steenstrupine.

Edited by Mariaan Webb
Creamer Media Senior Deputy Editor Online

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