Application of the Minex Process for extraction of metals from metallurgical wastes

Transcription

1 1 Application of the Minex Process for extraction of metals from metallurgical wastes Presenter: David Tait Location: Central Asia Minex, Astana

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3 The Minex Process 3 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 Large scale laboratory trials

4 The Minex Process 4 Cl 2 Chlorine gas Metal-bearing waste in Fluidised Bed Reactor (FBR) 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.

5 Temp (C) Metal separation: Melting points and boiling points 5 5,000 Metal BP Chloride BP Oxide BP Metal MP Chloride MP Oxide MP 4,000 3,000 2,000 1,000 0 Ag Au Cd Co Cr Cu Fe Ga Ge Hg In Mo Ni Pb U V Zn Element

6 Conceptual Flowsheet 6

7 The Minex Process 7 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 Achievable recovery >90% on most targeted metals

8 Development 8 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 , bench-scale tests at Cardiff University , RPS ran bench-scale extraction tests RPS ran continuous tests, large column testwork and recovery work 2012: market downturn, Minex suspended development

9 Pilot Testing 9 Lab scale Extraction- FBR Recovery: quench water bath and fractionation column

10 Copper slag samples and test conditions 10

11 Results 11 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

12 Waste Stabilization 12 Testing of mine waste: stabilisation for disposal Removal of arsenic

13 Potential Applications 13 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 oxideshydroxides 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)

14 Next steps 14 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.

15 The Minex Process 15 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 Achievable recovery >70% on most targeted metals Large scale laboratory trials

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