[go: up one dir, main page]

WO2025000050A1 - Procédé de traitement de minerai pour la récupération de métal - Google Patents

Procédé de traitement de minerai pour la récupération de métal Download PDF

Info

Publication number
WO2025000050A1
WO2025000050A1 PCT/AU2024/050704 AU2024050704W WO2025000050A1 WO 2025000050 A1 WO2025000050 A1 WO 2025000050A1 AU 2024050704 W AU2024050704 W AU 2024050704W WO 2025000050 A1 WO2025000050 A1 WO 2025000050A1
Authority
WO
WIPO (PCT)
Prior art keywords
ore
metal
hydroxide
crud
caustic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/AU2024/050704
Other languages
English (en)
Inventor
Bjorn Winther-Jensen
Paul Newling
Jonathon Clements
Ken Baxter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Element Zero Pty Ltd
Original Assignee
Element Zero Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2023902103A external-priority patent/AU2023902103A0/en
Application filed by Element Zero Pty Ltd filed Critical Element Zero Pty Ltd
Publication of WO2025000050A1 publication Critical patent/WO2025000050A1/fr
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C4/00—Crushing or disintegrating by roller mills
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
    • C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/30—Electrolytic production, recovery or refining of metals by electrolysis of melts of manganese
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/32—Electrolytic production, recovery or refining of metals by electrolysis of melts of chromium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02—Electrodes; Connections thereof
    • C25C7/025—Electrodes; Connections thereof used in cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/06—Operating or servicing
    • C25C7/08—Separating of deposited metals from the cathode

Definitions

  • the present invention relates to the field of ore processing.
  • the invention relates to processing ores to provide valuable metal products.
  • the present invention is suitable for recovery of metal from ores by chemical conversion, dissolution and electrodeposition.
  • 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.
  • An object of the present invention is to provide an improved process for extraction of metal from ore.
  • the caustic medium may be circulated in the process, with a small bleed required to remove impurities.
  • 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.
  • the molten caustic medium is sodium hydroxide (NaOH).
  • 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.
  • pre-processing steps including crushing and drying to remove moisture as well as water bound in the lattice structure.
  • ore for use in the present invention is chosen from the group comprising one or more of the following: iron ore including hematite, goethite, magnetite, titanomagnetite and pisolitic ironstone; aluminium containing ores including bauxite, cryolite and corundum; gold ores including gold-polysulfide, gold-quartz, gold-telluride, gold-tetradymite, gold-antimony, gold-bismuth-sulfosalt, gold-pyrrhotite, and gold-fahlore; manganese containing ores such as romanechite, manganite hausmannite and rhodochrosite; lead ores including galena, cerussite and anglesite; zinc ores including calamine and smithsonite; cobalt containing ores; uranium
  • the ore is iron ore, which is particularly rich in iron oxides, particularly in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH)), limonite (FeO(OH) n(H2O)) or siderite (FeCO3).
  • the ore is a silicon containing ore which is particularly rich in sodium silicate.
  • the term ‘ore’ is used broadly to include any naturally occurring mineral or solid material from which a metal or valuable mineral can be extracted profitably. These include mineral sands.
  • the present invention includes mixing mineral sands with a molten caustic medium to dissolve at least one metal species such as a metalloid from the ore, then subjecting the molten mixture to electrolysis to deposit at least one metal on a cathode and evolve oxygen at an anode.
  • the molten metal base or bases at elevated temperature may comprise a super-alkaline media.
  • metal containing moieties are chemically converted to solvable species and/or the resulting species are fully or partially dissolved in the molten metal base electrolyte.
  • sulphide ores for example, are converted to oxides.
  • Additional compounds may facilitate the dissolution or chemical conversion of the ore.
  • the addition of silicates may promote dissolution or chemical conversion of the ore.
  • the process of the present invention may include one or more bleed streams. Some steps of the process will build up materials such as solid fines, slimes, or breakdown products from chemicals. Their presence can lead to degradation of the overall performance of the process. Having a bleed from the relevant step removes these products and helps to maintains process performance.
  • the bleed flow will be sufficient to prevent major build-up of the aforementioned material, yet not so large as to waste useful material.
  • the bleed from the electrolysis step may be further processed and recirculated to the process of the present invention.
  • the bleed may be further processed to remove impurities so that the caustic medium can be returned to the leach.
  • the bleed can be fed back between the dissolution step and the electrolysis step.
  • Removal of impurities from the bleed may be carried out, for example, using a gravimetric approach to separate species having different densities.
  • the metal that collects on the cathode may be removed from the cathodes or starter sheets.
  • Starter sheets are cathodes made of metals such as iron or steel, that are removed from the process and may be sold in combination with the deposited metal.
  • the present invention further includes a metal separated from an ore according to the method of the invention.
  • embodiments of the present invention stem from the realization that a caustic medium can be used to convert ore to a liquid that can be electrochemically treated to deposit valuable metals onto a cathode. More particularly, the realisation extends to the fact that no carbon needs to be used in the process. When renewable energy is applied, no carbon dioxide is released to the atmosphere in any direct or supporting step.
  • FIG 1 illustrates the steps of the process of the current invention
  • FIG 2 illustrates in more detail, suitable apparatus and plant configurations for use in the process of the present invention
  • FIG 3 is a plot of iron ore solution concentration (wt%) against iron content in the dried iron ore
  • FIG 4 is a plot of current vs voltage for electrodeposition of iron from a hydroxide eutectic to illustrate energy consumption of the present invention
  • FIG 5 is a plot of x-ray diffraction measurements for iron ore sourced from the Pilbara region of Western Australia.
  • FIG 6 is a plot of silica input and sodium hydroxide consumption against the generation of sodium silicate, and water according to the present invention.
  • FIG 1 is a diagram illustrating the following process steps of the present invention:
  • • ore drying step (3) Ground ore from the mill is subjected to a drying step, which may include for example, passing through a dry cyclone. Oversize material may be returned to the mill for regrinding until it reaches the desired target size.
  • • chemical conversion step (4) The dry product is mixed into a caustic medium, such as a molten alkali metal or alkali earth at a volume flow rate that will allow proper mixing. Apparatus such as a series of cascade mixing tanks may be used to ensure a controlled chemical conversion followed by dissolution of solids.
  • electrowinning step (5) The molten product is subjected to electrowinning. For example, the molten product may be passed through electrowinning cells where the metal product is collected on nickel or mild steel cathodes. The cathode material may be chosen to optimise efficiency of removal of the metal.
  • the spent caustic media is bled from the electrowinning step, the impurities are removed, and the remaining cleaned caustic material is returned for use or as a ‘top up’ reagent at a convenient point in the process such as the chemical conversion step or the dissolution step, or after the electrowinning step.
  • Separation of the impurities as a crud from the caustic material is preferably carried out according to the following steps:
  • crud crushing (9) - The upper layer of crud comprising impurities is crushed.
  • crud milling (10) - The crushed crud is then milled in water before the resultant stream is thickened.
  • crud drying (11) The thickened crud stream is dried, for example, by spray drying methods.
  • the dried impurities may then be used for other purposes such as downstream processes. For example, they may be used as feedstock for creating value-added products such as geopolymers or zeolites. They may alternatively be subjected to further processing such as electroreduction to recover other valuable metals (such as aluminium or silicon) or metalloids.
  • further processing such as electroreduction to recover other valuable metals (such as aluminium or silicon) or metalloids.
  • the object of ore reclaim is to deliver ore fines at a controlled rate to a crusher.
  • fines may be delivered by trucks to a stockpile on a prepared pad situated close to the crushing facility and stockpiled adjacent a feed bin. Ore fines can be loaded into the feed bin by a front-end loader or by direct tipping or other suitable means.
  • Loading of fines to the feed bin can be controlled by any convenient means, such as a crusher operator who activates tipping from a suitable location such as a central control room.
  • a feeder such as an apron feeder under the feed bin discharges to a sacrificial conveyer which then discharges to an enclosed belt conveyer.
  • the primary crusher discharge conveyor may include a tramp metal detection and a belt magnet to remove extraneous metal from potentially damaging downstream equipment.
  • dust emission control in the ore reclaim area is provided by an extraction system within the reclaim structure.
  • the dust emission control system may for example, consist of a single dry bag house and the dust can be discharged back to the enclosed conveyor belt.
  • a sump pump may be provided in the basement level of the fines reclaim building to remove dust collected by washdown of the primary crushing area.
  • belt feeders are installed beneath the fine ore bin and discharge to respective high pressure grinding roll (HPGR) crushers.
  • HPGR high pressure grinding roll
  • a variable speed drive in each feeder may be used to maintain the level in the HPGR feed chute which ensures that the HPGR remains choke fed in normal operation
  • Tramp metal if detected by a dedicated metal detector on each feeder, may actuate a flop gate in the HPGR belt feeder discharge chute.
  • a metal detection can lead to diversion of the individual feeder discharge to a HPGR bypass conveyor. The stream containing the metal can then pass under a bypass magnet that removes the metal and the conveyor discharge can gravitate back to the HPGR discharge conveyor.
  • This system is designed to allow the crushers to remain online in the event of a metal detection event.
  • An HPGR typically has two rolls driven by synchronised variable speed drives which control the HPGR crusher throughput.
  • the crusher gap is typically controlled by hydraulic pressure on the movable rolls.
  • Tertiary crushed ore can gravitate directly to an HPGR discharge conveyor which conveys the crushed product to a two-stage air classification circuit.
  • oversize particles are removed from the ground ore.
  • ground ore from mill may be passed through a dry cyclone and oversize particle can be returned to mill for regrinding to target size.
  • the crushed ore may be passed through a dryer to remove water of crystallisation before the ore is fed to the chemical conversion step.
  • the leach feed is typically dried at elevated temperature and the off gas from the dryer can be used in part in the crushing circuit for heating and product transport, and in part in the spray dryer to evaporate water from the caustic waste solutions.
  • the dry product is collected and conveyed in part to the chemical conversion step and in part to the bleed.
  • dried and crushed iron ore may be fed from the dryer to a leach feed box by screw feeders which mix all feed streams to the fines leach circuit through operation of dart valves.
  • the dry product may be mixed into molten caustic medium at elevated temperature and at a volume flow rate that will allow proper mixing.
  • Chemical conversion may be carried out by many means.
  • a series of cascade mixing tanks ensures a controlled dilution of solids.
  • Agitated atmospheric leach tanks, with leach agitators may provide the necessary mixing and solids suspension for optimum reaction kinetics.
  • the last tank in the train may discharge to a pump box from where the leach discharge is pumped by the duty leach discharge pump to an electrowinning circuit.
  • the caustic medium is a metal base chosen from alkali metal bases such as lithium, sodium, potassium, rubidium or caesium hydroxide, or alkaline earth bases such as calcium, barium, or strontium metal hydroxides.
  • the metal base is chosen from lithium hydroxide, sodium hydroxide, potassium hydroxide or calcium hydroxide.
  • the caustic medium comprises 45 wt% to 100 wt% sodium hydroxide and/or potassium hydroxide.
  • One or more metal bases may be contacted with the ore, and combinations of metal bases may be in the form of a eutectic mixture.
  • Eutectic mixtures of sodium, potassium and/or lithium hydroxide is particularly preferred.
  • NaOH is preferred. Compared to KOH and LIOH, NaOH is also more potent when it comes to its chemical reactivity with metal oxides, but pure NaOH may not be as efficient as the combination of NaOH with KOH to form a eutectic system, which allows for lower operating temperature.
  • the caustic media comprising alkali metal or alkaline earth bases are contacted with the ore at elevated temperature, preferably a temperature above 160 °C, or above 200 °C, preferably above 250 °C, more preferably above 300 °C.
  • the alkali metal or alkaline earth bases are contacted with the ore at a temperature of 160 °C to 400 °C, preferably 200 °C to 350 °C, more preferably 250 °C to 350 °C.
  • most mixtures of NaOH and KOH have lower melting points than the constituent compounds.
  • the eutectic forms at 170 °C. If adsorbed water is present, such as in a 1 :1 :1 ratio of NaOH:KOH:H2O, the temperature of formation of the eutectic can be below 100 °C. However, water is undesired due to possible parasitic reactions during electroreduction process. In addition, water diluted eutectic mixtures do not have the same ability to chemically convert and dissolve metal oxides.
  • Molten metal bases, particularly hydroxides often include impurities such as water.
  • metal bases incorporated in the super-alkaline media of the present invention will include water in amounts of no more than one mole of water per mole of hydroxide. It is also possible to drive off water from the super-alkaline media by short term heating of the super-alkaline media to higher temperatures (i.e., > 500 °C). A shield of inert gas over the super-alkaline media can then be used to restrict or prevent reabsorption of water.
  • the metal bases used in the present invention may include small amounts of chemical impurities.
  • sodium hydroxide may form, or include small amounts of sodium carbonate (Na2(CO3)).
  • the metal is recovered by passing the molten product through electrowinning cells where the metal is collected on a cathode.
  • the anode is preferably positioned higher than cathode. Separation efficiency of deposited solid-state iron product from cathode will determine the best cathode material to use.
  • each tank house may comprise multiple banks of electrowinning cells.
  • the molten slurry within each cell can be distributed via an individual manifold located at the base of each cell.
  • sodium and potassium hydroxide are regenerated however several side reactions may consume additional reagent.
  • Plating takes place over a cycle time that depends on the desired thickness of metal on the cathode.
  • a critical operation impacting on the current efficiency of an electrowinning cell house is that of detecting and correcting short circuits (“shorts”) between anode / cathode pairs and poor contacts. Shorts and poor contacts can be individually identified, allowing the operator to take remedial action. Alternatively, hand-held gauss meters can be employed.
  • Cathode handling typically involves lifting a proportion of the plated cathodes from each cell at a time, such as by using an overhead cathode stripping crane and lifting cradle and then transporting them to cathode storage conveyers.
  • the metal deposit is removed from the cathode so that the cathodes can optionally be reused.
  • the cathodes may be sacrificial and remain combined with the deposited metal.
  • the cathodes can be cleaned of molten caustic media with hot water sprays and the washed cathodes stacked.
  • the hanger bars may be automatically stripped from the cathodes and passed to the starter sheet package bin for reuse. Starter sheets that have previously been prepared can be used to replace the cathodes removed.
  • a bleed stream may be taken from the main electrowinning circulating flow and is subjected to electrowinning to remove most of the leached iron in this stream. As the metal is plated, sodium and potassium hydroxide are regenerated in the bleed flow.
  • FIG 5 is a plot of x-ray diffraction measurements on iron ore from the Pilbara region of Western Australia.
  • Hematite (58% Fe) was treated for 1 hour in 50:50 NaOH:KOH eutectic at 350 °C resulting in complete conversion of hematite into sodium ferrite and potassium ferrite.
  • the ratio of iron ore to eutectic mixture was 10 wt%.
  • Iron ore was dried at 200 °C for 2 hours before introducing dried ore to eutectic. Due to high concentrations of potassium hydroxide, sodium hydroxide, sodium ferrite and potassium ferrite, x-ray diffraction did not detect impurities in the iron ore.
  • FIG 5 should be read in conjunction with the following TABLE 1
  • Step 8 Bleed Cooling
  • the bleed electrowinning discharge can be treated with ground ore to react the sodium and/or potassium silicates (which are water soluble) to iron silicate which is not water soluble.
  • Sodium and potassium oxides can also react which further improves sodium and potassium hydroxide recovery. Reaction of residual hydroxide with ore is one possible way to neutralise the ‘waste’ stream.
  • the slurry is then cooled, such as in a jacketed agitated tank in closed circuit with a cooling tower. Cooling a molten slurry causes the multiple phases in solution in the molten caustic to separate out. Once separation is complete molten caustic medium is pumped from the bottom of the kettle. Molten crud is pumped from the top of the kettle and allowed to solidify.
  • the crud produced by cooling of the electrowinning bleed stream can be recovered, stockpiled, and loaded into a crud crushing feed bin. Loading of crud into the feed bin may be controlled by the crusher operator from the central control room.
  • An apron feeder or similar under the feed bin may discharge to the crud crusher to produce a product suitable to feed the semi-autogenous grinding (SAG) mill.
  • SAG semi-autogenous grinding
  • the solidified crud can be milled in a mill to allow the sodium and potassium oxides in the crud to be dissolved for recovery.
  • the mill discharge can be cycloned to impart particle size classification.
  • Cyclone underflow can be recycled to a mill feed chute. Cyclone overflow will gravitate to a crud thickener where the undissolved solids can be recovered to the thickener underflow. Thickener overflow is pumped to a spray dryer.
  • Thickener underflow can be pumped to a filter surge tank to provide a buffer between the milling and filtration circuits.
  • the thickener underflow can be filtered and washed with wash liquor and filtrate is recycled to the crud thickener. Washed filter cake should be suitable for disposal.
  • the combined liquor streams from the crud milling and cathode washing can be treated in a spray dryer to recover the sodium and potassium hydroxide as a solid product for recycle to the leach. Waste heat from the ore dryer may be used in the spray dryer to evaporate the water.
  • Marra Mamba style fine ores (-6 mm) that are found in the Pilbara, Western Australia, using a 5 Mtpa modular process plant.
  • Marra Mamba ore has about 58% iron content and less than 1 % moisture when particle size is less than 6 mm.
  • Impurities include silica, alumina, and magnesia as well as trace content of phosphorus and titania.
  • Marra Mamba type -6 mm iron fine ore stockpile was conveyed by trucks to a mill and stockpiled. Front end loaders loaded fines to a feed bin. An ore reclaim conveyor discharged into an 1850 tonne live capacity fine ore bin providing approximately one (1) hour live capacity ahead of the crushing circuit. Withdrawal rate from the fine ore bin was matched to the crushing circuit availability of 87.4% corresponding to an average feed rate of 653 dry metric tonnes per hour in normal operation. Live capacity of the feed bin was about 650 tonnes giving approximately 1 hour surge capacity at design reclaim throughput.
  • Marra Mamba ore typically has less than about 1% moisture.
  • the crushed ore was passed through a dryer to remove water of crystallisation before the ore was fed to the chemical conversion step.
  • the leach feed was dried at a temperature of 700 °C.
  • the dry product was mixed at ⁇ 18% solids to melted NaOH (325 °C to 350 °C) at a volume flow rate that allowed proper mixing.
  • the consumption rate of sodium hydroxide was approximately 90 kg/tonne of ore.
  • the caustic NaOH media was required to be heated to processing temperature prior to adding ore, because the mixture tends to solidify quickly.
  • the proportion of solids added into the mixture had a maximum of 18 wt% at 58% iron ore grade. This maximum would be reduced if lower grade feed was used.
  • the output concentration of the processing circuit was approximately 5 wt% dissolved ore.
  • a series of four cascade mixing tanks ensured a controlled dilution of solids down to approximately 5% solids.
  • Nickel lined vessels were appropriate for this chemistry and temperature. It will be readily apparent to the person skilled in the art that the vessels can be made of any convenient material, such as nickel 200, stainless steel with metal lining, Hastelloy® such as Hastelloy® C-276, Inconel alloy such as Inconel 625 or single crystal corundum. Other materials such as zinc oxide, cerium(IV) oxide, magnesium oxide and nickel oxide may be suitable materials for manufacture of vessels, but their suitability depends on their mechanical properties. Mixing efficiency was important along with maintaining heat in the leach tanks and leach agitators provided the necessary mixing. The last tank in the cascade discharged to a pump box from where the leach discharge was pumped by the duty leach discharge pump to a distribution circuit which split the leach discharge equally between five electrowinning circuits.
  • Each tank house comprised four banks of electrowinning cells of 69 cathodes and 70 anodes each.
  • the electrowinning tanks can be made of any convenient material, such as nickel 200, stainless steel with metal lining, Hastelloy® such as Hastelloy® C-276, Inconel alloy such as Inconel 625 or single crystal corundum.
  • Other materials such as zinc oxide, cerium(IV) oxide, magnesium oxide and nickel oxide may be suitable materials for manufacture of vessels, but their suitability depends on their mechanical properties.
  • Each cathode had 2 m 2 of plating area.
  • the overall electro-winning cell houses were designed for an iron cathode production of 2,870,000 tpa, plus the additional iron electrowon in the bleed electrowinning circuit used for the impurity removal circuit.
  • Each bank had a dedicated rectifier operating at a voltage of 204 V and a current of 276,000 A.
  • the molten slurry within each cell was distributed via an individual manifold located at the base of each cell at a flow rate of between 1.80 l/min/m 2 based on a current density of 1000 A/m 2 .
  • Solution from the cell overflows into a common pipe header by which the molten slurry gravitates to a heated circulation tank.
  • a thin sheet of steel was guillotined to produce starter sheets of suitable size for cathodes.
  • a handing bar was automatically fitted to the starter sheet before the prepared cathodes were stacked on a rack for use in the five tank houses.
  • electrowinning cells were stripped of loaded cathodes, a set of starter sheets is replaced in individual electrowinning cells as required.
  • Cathode handling involved lifting one third (15) of the plated cathodes from each cell at a time with an overhead cathode stripping crane and lifting cradle and then transporting them to a cathode storage conveyer. There they were cleaned of molten caustic with hot water sprays and the washed cathodes were transferred to conveyors feeding a stacking machine. The hanger bars were stripped from the cathodes and passed to the starter sheet package bin for reuse.
  • the molten caustic electrowinning/chemical conversion media was bled to remove build-up of impurities.
  • the bleed stream was cooled in “crud” baths.
  • the impurities formed on the upper level of the “crud” baths.
  • the relatively clean, now solid, caustic at the bottom was remelted and returned to the circuit with “top-up” (replenishing) reagent and the other caustic recovered in the aqueous circuit.
  • the upper layer of crud was crushed and then milled in water before the resultant stream was thickened and sent for disposal.
  • the thickener overflow was sent to a spray dryer to recover itinerant caustic soda, with the resultant solids being returned to the process.
  • a bleed stream was taken from the main electrowinning circulating flow and subjected to electrostripping to remove most of the leached iron in the stream. As the metal is plated, sodium and potassium hydroxide are regenerated in the bleed flow.
  • the bleed electrowinning discharge is treated with ground ore to react the sodium and potassium silicates which are water soluble to iron silicate which is not water soluble. Sodium and potassium oxides are also reacted which further improves sodium and potassium hydroxide recovery.
  • An apron feeder under the feed bin discharges to the crud crusher to produce a product suitable to feed a semi-autogenous grinding (SAG) mill.
  • SAG semi-autogenous grinding
  • the solidified crud was milled in a single stage SAG mill to allow the sodium and potassium oxides in the crud to be dissolved for recovery.
  • the SAG mill discharge was cycloned to impart classification.
  • Cyclone underflow was recycled to the SAG mill feed chute. Cyclone overflow gravitated to the crud thickener where the undissolved solids were recovered to the thickener underflow. Thickener overflow was pumped to a spray dryer circuit.
  • Thickener underflow was pumped to a filter surge tank to provide a buffer between the milling and filtration circuits.
  • the thickener underflow was filtered and washed on two belt filters. Wash liquor and filtrate was recycled to the crud thickener. The washed filter cake was suitable for disposal.
  • Step 11 - Spray Dryer The combined liquor streams from the crud milling and cathode washing were treated in a spray dryer to recover the sodium and potassium hydroxide as a solid product for recycle to the leach.
  • the saturation point The maximum concentration of ore that could be dissolved in the molten caustic (the saturation point) has been measured at 300 °C for different ore qualities after one- and four-hours’ exposure to the hydroxide. There was no appreciable difference in the amount of ore dissolved after one and four hours. The saturation point is dependent on the ore quality.
  • EXAMPLE 3 Bench Scale Electrowinning Optimisation
  • Initial bench scale electrowinning test work was based on a cathode area of 8 cm 2 operating at 310 °C.
  • a caustic medium of NaOH and KOH (5:1 mix ratio) was used to lower the melting point of the hydroxide.
  • FIG 4 is a plot of current vs voltage for electrodeposition of iron from hydroxide eutectic to illustrate energy consumption of the present invention.
  • the eutectic was at 310 °C with 7 wt% dried Pilbara ore (55 wt% Fe) in solution.
  • the plot illustrates the energy consumption per ton of iron produced as a function of cell potential (upper trace) including 90% estimated Faradaic (current) efficiency.
  • the lower trace represents the current density.
  • the coating deposited under these conditions on nickel or iron cathodes had an iron content between 95 wt% and 98 wt% depending on the ore quality.
  • the dissolved silica and alumina was not removed from the molten hydroxide prior to the electrowinning and the applied voltage/current, where lower voltage/current always gave higher iron content.
  • the impurity in the deposited iron was oxygen, not silica (or silicon) or alumina (or aluminium).
  • the first step in the electrochemical production of metallurgical grade silicon is pre-processing of silicon feedstock.
  • This step may vary depending on the purity of silicon feedstock.
  • lower silica content beach sand contains organic and inorganic impurities which must be removed before electroreduction to limit or eliminate the amount of impurities transferred into the final product Australian beach sand was tested, the sand having a silica content of 69.8% and 73.4% SiO2).
  • the processable range is higher allowing production of metallurgical grade silicon from higher and lower grade silica sources.
  • Preprocessing of lower grade silica feedstocks is described below (under the heading ‘Preparation of silica from beach sand’.)
  • the anode may remain the same whereas the cathode is replaced to attract impurities with the lower silica (sodium silicate) potential.
  • the cathode is changed for electroreduction and deposition of metallurgical grade silicon.
  • the HCI wash was performed until no further sign of foam or bubbles was noticed, indicating that organic impurities had been removed;
  • the hydrochloric acid treatment was followed by washing with deionised water;
  • the wet sand was distributed on a tray and dried in an oven at 200 °C for 4 hours;
  • the dried sand was placed in a sodium hydroxide bath at 350 °C for 2 hours to form sodium silicate (Na2SiO3), in accordance with the following equation;
  • the dried silica was ground to produce fine powder.
  • Quartz grain size varied from roughly 4 to 8 mm in size
  • silica or sodium silicate have a negative impact on nickel 200 containment, wherein after a certain time some nickel is leached into the electrolyte resulting in nickel impurities in the silicon product. This nickel leaching is believed to be facilitated by silica or silicon and was not previously noticed for iron ore processing into iron, where silica levels are significantly lower than in the above-mentioned system. It would be beneficial to better understand the nickel dissolution mechanism in presence of silica or sodium silicate.
  • Other potential vessel materials may be useable, such as, stainless steel, Hastelloy® such as Hastelloy® C- 276, Inconel alloy such as Inconel 625 or single crystal corundum. Other materials such as zinc oxide, cerium(IV) oxide, magnesium oxide and nickel oxide may be suitable materials for manufacture of vessels.
  • Metallurgical grade silicon (98% Si) is used extensively in the metallurgical industry, or as feedstock for higher purity silicon used mainly in the solar photovoltaics, and semiconductor industries.
  • Solar-grade polysilicon typically has purity levels of 6N (99.9999% Si) to 8N (99.999999% Si) and it is used to make solar cells. Some premium solar cells may use 9N (99.9999999% Si) polysilicon. The purity of electronic grade polysilicon generally ranges between 9N (99.9999999% Si) and 12N (99.9999999999% Si).
  • nickel oxide concentrate ( ⁇ 1% Ni) was mixed with (i) sodium hydroxide, and separately (ii) a eutectic mixture of sodium and potassium hydroxide in a nickel 200 container at 350 and 250 °C, respectively. Dissolution was performed at atmospheric pressure. The species produced were soluble in the electrolyte indicating its suitability as a candidate for electrodeposition.
  • Nickel Upon passing an electric current through the solution, nickel was deposited onto the cathode in an electroplating process. Nickel concentrate often contains sizable volumes of iron oxide, in which case co-deposition and formation of nickel-iron alloys (also known as ferronickel) is possible. [00187] Other aspects, components and steps of the processing circuit remain the same or similar to those described earlier in this patent specification.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

L'invention concerne un procédé de séparation de métal à partir de minerai, comprenant les étapes consistant à : (a) éventuellement prétraiter le minerai, (b) mélanger le minerai avec un milieu caustique tel qu'une ou plusieurs bases de métaux alcalins ou alcalinoterreux à une température élevée supérieure à 160 °C, de préférence de 200 °C à 350 °C ou plus préférablement de 250 °C à 350 °C, et (c) soumettre le mélange à une électrolyse pour déposer au moins un métal au niveau d'une cathode et dégager de l'oxygène au niveau d'une anode. Dans un mode de réalisation, le milieu caustique à température élevée dissout au moins une espèce métallique à partir du minerai Bien que l'invention soit applicable à une large gamme de minerais, généralement le minerai est un minerai de fer, un sable minéralisé ou un minerai de nickel
PCT/AU2024/050704 2023-06-30 2024-06-28 Procédé de traitement de minerai pour la récupération de métal Pending WO2025000050A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2023902103 2023-06-30
AU2023902103A AU2023902103A0 (en) 2023-06-30 Ore processing method for metal recovery

Publications (1)

Publication Number Publication Date
WO2025000050A1 true WO2025000050A1 (fr) 2025-01-02

Family

ID=93936541

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2024/050704 Pending WO2025000050A1 (fr) 2023-06-30 2024-06-28 Procédé de traitement de minerai pour la récupération de métal

Country Status (1)

Country Link
WO (1) WO2025000050A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622063A (en) * 1945-06-30 1952-12-16 Angel Erik Gustaf Robert Electrolytic production of iron and iron alloys
WO1981003500A1 (fr) * 1980-05-28 1981-12-10 Univ Cardiff Recuperation de metaux lourds dans des procedes de production de metaux ferreux
GB2159139B (en) * 1984-05-23 1988-06-02 Preussag Ag Process for the recovery of tin from oxide or oxide/sulphide starting materials/concentrates which contain little tin
US5194124A (en) * 1991-11-26 1993-03-16 E. I. Du Pont De Nemours And Company Molten salt electrolytic beneficiation of iron oxide-containing titaniferous ores to produce iron and high-grade TiO2

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622063A (en) * 1945-06-30 1952-12-16 Angel Erik Gustaf Robert Electrolytic production of iron and iron alloys
WO1981003500A1 (fr) * 1980-05-28 1981-12-10 Univ Cardiff Recuperation de metaux lourds dans des procedes de production de metaux ferreux
GB2159139B (en) * 1984-05-23 1988-06-02 Preussag Ag Process for the recovery of tin from oxide or oxide/sulphide starting materials/concentrates which contain little tin
US5194124A (en) * 1991-11-26 1993-03-16 E. I. Du Pont De Nemours And Company Molten salt electrolytic beneficiation of iron oxide-containing titaniferous ores to produce iron and high-grade TiO2

Similar Documents

Publication Publication Date Title
AU2016204728B2 (en) Method for the Extraction and Recovery of Vanadium
Fthenakis et al. Life cycle inventory analysis of the production of metals used in photovoltaics
US4295881A (en) Process for extraction of platinum group metals from chromite-bearing ore
US9630844B2 (en) Hydrometallurgical process for the recovery of tellurium from high lead bearing copper refinery anode slime
US4272341A (en) Process for recovery of metal values from lead-zinc ores, even those having a high carbonate content
Antuñano et al. Hydrometallurgical processes for Waelz oxide valorisation–An overview
MXPA03000209A (es) Produccion de oxido de zinc a partir de minerales solubles en acido utilizando un metodo de precipitacion.
CN109890988B (zh) 用于处理矿石的集成湿法冶金和高温冶金方法
CN103781923A (zh) 用于纯化氧化锌的方法
JP2002511527A (ja) 湿式処理による製鋼所塵埃の処理方法
US11560609B2 (en) Method of extracting metals from polymetallic sulphide ores or concentrates
WO2025000050A1 (fr) Procédé de traitement de minerai pour la récupération de métal
CN109913647B (zh) 一种回收铋中矿中铜、锌的湿法处理方法
CN116411169B (zh) 无铅热镀锌浮渣的综合利用方法
WO1981003500A1 (fr) Recuperation de metaux lourds dans des procedes de production de metaux ferreux
EP0040659B1 (fr) Récupération de métal lourd au cours de procédés de production de métal ferreux
WO2017117626A1 (fr) Précipitation de nickel et de cobalt
Pietrzyk et al. Silver recovery from zinc metallurgical sludge–analysis of solutions
EP3189170A1 (fr) Procédé et appareil pour le raffinage de métaux
JP4914976B2 (ja) 硫酸亜鉛溶液からのタリウム除去方法
Jyrkonen et al. Processing of PGM containing Ni/Cu bulk concentrates in a sustainable way by Outotec Direct Nickel Flash Smelting process
Jiang et al. A process for the production of Zn powder by alkaline treatment of brass smelting ash at industrial scale
CN120457224A (zh) 锌回收方法和铁酸锌分解方法
Urmosi et al. Electrochemical reactor for gallium recovery from the bauxite treating Bayer process

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 24829643

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: AU2024308662

Country of ref document: AU