EP-4735672-A1 - ORE PROCESSING METHOD FOR METAL RECOVERY

Abstract

The invention relates to a method of separating metal from ore comprising the steps of: (a) optionally pre-processing the ore, (b) mixing the ore with a caustic medium such as one or more alkali metals or alkaline earth bases at elevated temperature above 160°C, preferably 200°C to 350°C, or more preferably 250°C to 350°C and (c) subjecting the mixture to electrolysis to deposit at least one metal at a cathode and evolve oxygen at an anode. In one embodiment, the caustic medium at elevated temperature dissolves at least one metal species from the ore. While the invention is applicable to a wide range of ores, typically the ore is an iron ore, mineral sand or nickel ore.

Inventors

• WINTHER-JENSEN, BJORN
• Newling, Paul
• Clements, Jonathon
• Baxter, Ken

Assignees

• Element Zero Pty Limited

Dates

Publication Date

20260506

Application Date

20240628

Claims (16)

1. 1 . A method of separating metal from ore comprising the steps of: (a) optionally pre-processing the ore, (b) mixing the ore with a caustic medium at elevated temperature above 160 °C, and (c) subjecting the mixture to electrolysis to deposit at least one metal at a cathode and evolve oxygen at an anode.
2. 2. A method according to claim 1 , wherein the elevated temperature is 160 °C to 400 °C, preferably 200 °C to 350 °C, more preferably 250 °C to 350 °C and the caustic medium is optionally a molten caustic medium.
3. 3. A method according to claim 1 wherein the caustic medium at elevated temperature dissolves at least one metal species from the ore.
4. 4. A method according to claim 1 , wherein the caustic medium comprises one or more alkali metal or alkaline earth bases.
5. 5. A method according to claim 1 , wherein the ore is an iron ore chosen from hematite, goethite, limonite, siderite, magnetite, titanomagnetite, pisolitic ironstone and combinations thereof, and the metal deposited is from 95 wt% to 98 wt% iron.
6. 6. A method according to claim 1 , wherein the ore is a mineral sand and the metal species is a metalloid.
7. 7. A method according to claim 1 , wherein the ore is a nickel ore.
8. 8. A method according to claim 1 , wherein the caustic medium is a metal base chosen from lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, caesium hydroxide, calcium hydroxide, barium hydroxide, or strontium hydroxide or combinations or eutectic mixtures thereof.
9. 9. A method for separating metal from ore according to claim 1 , the method comprising the steps of: (a) pre-processing the ore by, (a)(i) crushing the ore to a desired particle size; (a)(ii) drying the crushed ore; (b) mixing the crushed, dried ore with a caustic medium at elevated temperature; (c) passing the mixture through electrolysis cells to collect metal at a cathode and release oxygen at an anode; and (d) removing the collected metal.
10. 10. A method according to claim 9, wherein the collected metal is separated from the cathode.
11. 11. A method according to claim 9, wherein the cathode and the metal collected are of the same material.
12. 12. A method for separating metal from ore according to claim 2, wherein the method includes the further steps of: (e) bleeding and cooling a spent caustic material from the electrolysis cells; (f) separating the spent liquor into a solid crud comprising impurities and a cleaned caustic medium; and (g) returning the cleaned caustic medium to the mixing step.
13. 13. A method according to claim 12, which further includes the steps of: (h) crushing any solid crud, (i) milling the crud in liquid to form a suspension; (j) thickening the suspension; and (k) drying, preferably spray drying, the thickened suspension to create dried crud.
14. 14. A method according to claim 13, wherein the dried crud is used as a feedstock for further processes.
15. 15. A metal separated from an ore by a method according to any one of the preceding claims.
16. 16. A system for carrying out the method of any one of claims 1 to 14.

Description

ORE PROCESSING METHOD FOR METAL RECOVERY FIELD OF INVENTION [0001] The present invention relates to the field of ore processing. [0002] In one form, the invention relates to processing ores to provide valuable metal products. [0003] In one particular aspect the present invention is suitable for recovery of metal from ores by chemical conversion, dissolution and electrodeposition. [0004] It will be convenient to hereinafter describe the invention in relation to iron ore, particularly the reduction of iron from haematite ore however it should be appreciated that the present invention is not so limited but extends to a wide range of ores, and a wide range of metals. BACKGROUND ART [0005] It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor’s knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein. [0006] Traditionally, reduction of metals such as iron from ore, particularly haematite ore, is done in a pyrometallurgical process which produces significant greenhouse gases, particularly carbon dioxide. Carbon Is alloyed with iron to make steel as part of this process (normally to excessive levels when first reduced in a blast furnace) to produce pig iron and then reduced by oxidation in a basic oxygen steelmaking furnace. More recently, a direct reduced iron (DRI) process has been progressively displacing blast furnace capacity. While this pathway is offers reduced carbon dioxide emissions, it is far from being carbon neutral. The DRI process uses high operating temperatures and has high inefficiencies. In addition, the process also does not work well with low grade ores (i.e., below 65 wt% Fe). [0007] The alternative treatment methods typically include extractive metallurgy to remove metals from natural mineral deposits. Extractive metallurgy techniques are commonly grouped into three categories: hydrometallurgy, pyrometallurgy and electrometallurgy including electrorefining and electrowinning. Many of these processes also use high operating temperatures and have high inefficiencies. SUMMARY OF INVENTION [0008] An object of the present invention is to provide an improved process for extraction of metal from ore. [0009] It is a further object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems. [0010] In a first aspect of embodiments described herein there is provided a method of separating metal from ore comprising the steps of: (a) optionally pre-processing the ore, (b) mixing the ore with a molten caustic medium to dissolve at least one metal species from the ore, and (c) subjecting the molten mixture to electrolysis to deposit at least one metal on a cathode and evolve oxygen at an anode. [0011] The caustic medium may be circulated in the process, with a small bleed required to remove impurities. [0012] The molten caustic medium preferably comprises one or more alkali metal or alkaline earth bases. Alkali metal or alkaline earth bases suitable for use in the present invention are preferably hydroxides, although other bases such as metal oxides or metal ammonium species may also be used. In one particularly preferred embodiment, the molten caustic medium is sodium hydroxide (NaOH). [0013] The ore fed into the process of the present invention is typically subjected to pre-processing steps including crushing and drying to remove moisture as well as water bound in the lattice structure. In a second aspect of embodiments described herein there is provided a method for the separating metal from ore comprising the steps of: (a)(i) crushing the ore to a desired particle size; (a)(ii) drying the crushed ore; (b) mixing the crushed, dried ore with a caustic medium at elevated temperature, preferably molten caustic medium; (c) passing the mixture through electrolysis cells to collect metal on a cathode and release oxygen at an anode; (d) removing the collected metal from the cathodes or using a cathode (initially in the form of a starter-sheet) that is of the same material as the metal collected. [0014] It will be apparent to the person skilled in the art that a very wide range of ores can be processed according to the present invention. Preferably, ore for use in th