Application of the Minex Process for extraction of metals ......Application of the Minex Process for extraction of metals from metallurgical wastes ... •Other process only remove

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© SRK Consulting (UK) Ltd 2017. All rights reserved.

Presenter:

Location:

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Application of the Minex Process

for extraction of metals from

metallurgical wastes

David Tait

Central Asia Minex, Astana

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© SRK Consulting (UK) Limited 2017 version: Jan2017

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• A novel metal extraction process:

• Precious metals, rare metals, rare-earth, Cu, Fe

• Extraction method:

• Chlorine gas

• High temperature

• Applicable to wide range of solid materials:

• Mine waste

• Metallurgical wastes

• Ferroalloy, bauxite…

• Stabilises waste materials

• Recovers target metals as sellable product

• Achievable recovery >90% on most targeted metals

The Minex Process

Large scale laboratory trials

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The Minex Process

Metal-bearing

waste in

Fluidised Bed

Reactor (FBR) Chlorine gas

Cl2 Metal

chloride

gas

“As a general rule: chloride salts have a lower boiling point than the pure metal or metal oxides... And therefore require a lower energy input.” • By creating a metal chloride salt at a high temperature (greater than the

boiling point of the salt) the salt changes from a solid into a gas.

• This gas can easily be separated from the remaining solids and transports the extracted metals for recovery.

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Metal separation: Melting points and boiling points

0

1,000

2,000

3,000

4,000

5,000

Ag Au Cd Co Cr Cu Fe Ga Ge Hg In Mo Ni Pb U V Zn

Tem

p (

C)

Element

Metal BP Chloride BP Oxide BP

Metal MP Chloride MP Oxide MP

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Conceptual Flowsheet

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• Process is selective and minimises cost by removing targeted metals

extracted in a single pass

• Other process only remove one metal at a time e.g. Ausmelt, Avalon process

• Requires sub-5 mm materials:

• Process does not require expensive, energy intensive pre-treatment such

as fine grinding prior to metals extraction

• Process is low water consumer:

• No need for large downstream water treatment plants

• Residual solids are benign therefore eliminating environmental hazard and

can be used for profitable purposes or landfill


The Minex Process

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• Idea in 2003

• Development team:

• Dr Robert Bowell, Dr Matt Dey (SRK UK)

• Dr Keith Williams (University of Cardiff, UK)

• Ownership: SRK UK & Minex UK Ltd

• Testing undertaken

• 2003-2005, bench-scale tests at Cardiff University

• 2007-2009, RPS ran bench-scale extraction tests

• 2009-2011 RPS ran continuous tests, large column testwork and recovery

work

• 2012: market downturn, Minex suspended development

Development

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Pilot Testing

Lab scale Extraction- FBR

Recovery: quench water bath

and fractionation column

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Copper slag samples and test conditions

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Results

• Best metal extractions (up to 99.9%) were achieved in the Acid Blow Down Filter

Cake under the test conditions at 1000°C

• 900°C test gave best results on slag samples #2, 3 and 4.

• Lower extraction results attained at 1000°C on slag samples 2, 3 and 4 are

likely due to sintering of the slag at the high temperature. The sintering would

have a negative affect on the metal extractions by reducing surface contact

with HCl

• The high metal extractions realized in the program indicated that the slag samples

could be successfully processed with the technology

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Waste Stabilization

• Testing of mine waste: stabilisation for disposal

• Removal of arsenic

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Potential Applications

• Extraction of metals from mine wastes, metallurgical wastes in a single step with

recovery of metals proportional to BP of metal chlorides to form metal oxides-

hydroxides

• Complex extraction of precious, rare, rare-earth metals and other minerals from the

enrichment plant tailings and slag

• Stabilization of mine and process wastes

• separate high concentration/low volume material from low concentration/high

volume

• Separation of iron from aluminium/bauxite without production of large volumes of red

mud (conceptual)

• Waste dust re-treatment from ferroalloy production (conceptual)

• Separation of iron from alumina production with minimal water usage - no red mud

formed (conceptual)

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• Aim:

• To develop the technology/expand upon current testing towards full scale

testing and operation:

• Refinement, optimisation, application to other materials

• SRK & Minex seeking partner to acquire technology and/or facilitate

development and up-scaling

• Next phase:

• Pilot plant testing

• Recoveries and economics:

• Project specific: costs & recovery will depend on raw materials, plant size

etc.

Next steps

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• A novel metal extraction process:

• Precious metals, rare metals, rare-earth, Cu, Zn etc

• Applies:

• Chlorine gas

• High temperature

• Applicable to wide range of solid materials:

• Mine waste

• Metallurgical wastes

• Ferroalloy, bauxite…

• Stabilises waste materials

• Recovers target metals as sellable product


The Minex Process

Large scale laboratory trials

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Application of the Minex Process for extraction of metals ......Application of the Minex Process for extraction of metals from metallurgical wastes ... •Other process only remove