US20090293680A1 - Processing of Metal Values from Concentrates - Google Patents

Processing of Metal Values from Concentrates Download PDF

Info

Publication number
US20090293680A1
US20090293680A1 US12/225,172 US22517207A US2009293680A1 US 20090293680 A1 US20090293680 A1 US 20090293680A1 US 22517207 A US22517207 A US 22517207A US 2009293680 A1 US2009293680 A1 US 2009293680A1
Authority
US
United States
Prior art keywords
metal value
sulphate
vessel
iron
metal
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.)
Abandoned
Application number
US12/225,172
Other languages
English (en)
Inventor
Ian Christopher Ritchie
Victor John Ketcham
Karel John Osten
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.)
DUNDEE PRECIOUS (BARBADOS) Inc
Original Assignee
DUNDEE PRECIOUS (BARBADOS) Inc
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 AU2006901575A external-priority patent/AU2006901575A0/en
Application filed by DUNDEE PRECIOUS (BARBADOS) Inc filed Critical DUNDEE PRECIOUS (BARBADOS) Inc
Assigned to DUNDEE PRECIOUS (BARBADOS) INC. reassignment DUNDEE PRECIOUS (BARBADOS) INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: RITCHIE, IAN CHRISTOPHER, OSTEN, KAREL JOHN, KETCHAM, VICTOR JOHN
Publication of US20090293680A1 publication Critical patent/US20090293680A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C22B11/08—Obtaining noble metals by cyaniding
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C22B11/04—Obtaining noble metals by wet processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B15/00—Obtaining copper
    • C22B15/0063—Hydrometallurgy
    • C22B15/0065—Leaching or slurrying
    • C22B15/0067—Leaching or slurrying with acids or salts thereof
    • C22B15/0071—Leaching or slurrying with acids or salts thereof containing sulfur
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B15/00—Obtaining copper
    • C22B15/0063—Hydrometallurgy
    • C22B15/0084—Treating solutions
    • C22B15/0089—Treating solutions by chemical methods
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/08—Sulfuric acid, other sulfurated acids or salts thereof
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B30/00—Obtaining antimony, arsenic or bismuth
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to an improved process for the recovery of metal values, in particular copper and gold, from metal-bearing concentrates.
  • the present invention also relates more particularly to an improved process for the recovery of metal values, in particular copper and gold, from metal-bearing concentrates by means of a high temperature pressure oxidation process followed by cyanidation of the resultant high temperature pressure oxidation residue.
  • the present invention also relates more particularly but not exclusively to a high temperature pressure oxidation process in which there is controlled oxygen addition to the first compartment of a pressure vessel such as a substantially continuously operated autoclave, and also more particularly relates to controlled oxygen addition to approximately the first 50% of the total volume of the continuously operated autoclave.
  • the present invention also relates more particularly but not exclusively to a high temperature pressure oxidation process in which the Oxygen Reduction Potential (ORP) of the reaction slurry in the first compartment, and typically approximately the first 50% of die total volume, of a pressure vessel such as a substantially continuously operated autoclave, is kept below about 425 mV, and preferably below about 400 mV, when measured with a standard platinum (Pt) electrode against a standard silver/silver chloride (Ag/AgCl) electrode, and the soluble ferric to ferrous molar ratio is below about 1:1.
  • ORP and ferric and ferrous iron assays referred to above are those obtained by rapid cooling to room temperature of a sample of slurry withdrawn from the autoclave within one hour and then filtered for assay purposes.
  • hydrometallurgical processes for treating copper sulphide minerals that also contain arsenic are directed teds the generation of an acidic copper sulphate solution containing soluble copper, which is typically recovered therefrom by a combination of solvent extraction and electrowinning.
  • the arsenic component of the feed material is converted into an insoluble arsenic-containing phase such as hydrated ferric arsenate [FeAsO 4 2H 2 O].
  • This particular phase also occurs in nature as the mineral scorodite.
  • the hydrated ferric sulphate produced by the hydrometallurgical processes can be safely disposed of in a conventional tailings impoundment.
  • Most of the hydrometallurgical processes for treating copper sulphide minerals generally fall within the general designation of pressure oxidation processes.
  • Meta-stable iron compounds such as basic ferric sulphate [Fe(OH)SO 4 ] and any copper-containing precipitates such as an iron-copper-arsenate-sulphate in the residue will decompose (break down) under the alkaline pH conditions required for gold/silver cyanidation and thus bring about an increase in the lime and cyanide consumption, thereby decreasing the economic efficiencies of the overall process.
  • the abovementioned solid components present in the leach residue break down during the cyanidation step, generating excess acid and reactive sulphate compounds that must be subsequently neutralised.
  • the present invention seeks to overcome at least. some of the aforementioned disadvantages.
  • a method for the recovery of metal values from a metal value-bearing material containing arsenic and/or antimony and a source of sulphate ions such as a sulphide ore or concentrate comprising the steps of:
  • the slurry from step (b) may be maintained at a temperature in the range of from about 70° C. to about 100° C. for a period in the range of from about 15 minutes to about 4 hours prior to separating the metal value-containing solution from the solid leach residue.
  • a method for the recovery of metal values from a metal value-bearing material containing arsenic and/or antimony and a source of sulphate ions such as a sulphide ore or concentrate comprising the steps of:
  • the vessel of step (b) will typically be a pressure vessel such as an autoclave, and more typically a substantially continuously operated autoclave.
  • Up to approximately the first 50 % of the total volume of the vessel of step (b) may be kept below about 425 mV and typically below about 400 mV. Up to approximately 50% of the remaining volume of the vessel of step (b) may be allowed to increase above about 425 mV and typically substantially above about 425 mV.
  • the slurry from step (b) may be maintained at a temperature in. the range of from about 70° C. to about 100° C. for a period in the range of from about 15 minutes to about 4 hours prior to separating the metal value-containing solution from the solid leach residue.
  • a method for the recovery of metal values from a metal value-containing feed material containing arsenic and/or antimony and a source of sulphate ions such as a sulphide ore or concentrate comprising the steps of:
  • the vessel of step (b) will typically be a pressure vessel such as an autoclave, and more typically a substantially continuously operated autoclave.
  • Up to approximately the first 50% of the total volume of the vessel of step(b) may be kept below about 425 mV and typically below about 40 mV. Up to approximately 50% of the remaining total volume of the vessel of step A) may be allowed to increase above about 425 mV and typically substantially above about 425 mV.
  • the slurry from step (b) may be maintained at a temperature in the range of from about 70° C. to about 100° C. for a period in the range of from about 15 minutes to about 4 hours prior to separating the metal value-containing solution from the solid leach residue.
  • pressure oxidation or “pressure oxidation step” or “oxidative conditions under elevated temperature and pressure” used herein refer to a high temperature/high pressure leach process operated under acidic oxidising conditions.
  • One particular aspect of the present invention is based upon the realisation that it is possible to adjust the processing conditions such that they prevent the formation of insoluble copper-containing precipitates during the high temperature pressure leaching process to extract metal values such as copper from a metal value-containing material such as a sulphide ore that also contains arsenic and/or antimony.
  • Another particular aspect of the present invention is based upon the realisation that it is possible to adjust the processing conditions to promote the formation of solid iron(III) sulphate containing-products in the residue derived from the pressure leaching process that are stable under the alkaline pH conditions at ambient temperature that are used to recover the gold and/or silver values from the said residue.
  • this solid iron(III) sulphate containing-product is referred to as a “pH stable iron(III) sulphate”.
  • Included in the means of promoting the formation of the pH stable iron(III) sulphate product are means of controlling (decreasing) the free acid generated during the pressure oxidation step by addition of certain additives and/or control of the slurry ORP in typically about the first 50% of the total volume of the vessel such as a continuous autoclave used for the pressure oxidation step. This latter means is achieved by limiting the rate of oxygen injection into about the first 50% of the total volume of the continuous autoclave.
  • the result of the correct selection of the high temperature/high pressure leaching conditions for treating metal value-bearing materials containing arsenic and/or antimony is that the majority of the arsenic and/or antimony reports to a solid residue as an environmentally stable mixed iron-arsenic and/or iron-antimony solid species mixed with pH stable iron(III) sulphate products.
  • copper losses to the residue are minimised by prevention of precipitation of a copper-iron-sulphate-arsenate, while cyanidation of the gold and/or silver content of the leach residue is enhanced because of the promotion of precipitation of pH stable iron(III) sulphate products such as jarosite-type minerals rather than basic iron sulphate.
  • the present invention is accordingly concerned with the development of economically viable conditions that can at least partially achieve one or more of (a) minimizing copper losses to the leach residue, (b) ensuring that the arsenic and/or antimony components of the feed material report to the residue in an environmentally stable form, and (c) preventing the formation of solid residues that break down during the gold and/or silver cyanidation step and a concomitant increase in lime and cyanide consumption in the case where the initial feed material contains recoverable gold and/or silver.
  • the metal value-bearing material containing arsenic and/or antimony is a copper-bearing material containing arsenic and/or antimony, in particular a copper sulphide containing arsenic and/or antimony, and even more particularly a mixed copper-gold sulphide containing arsenic and/or antimony.
  • the metal value-containing material is an ore or concentrate that contains arsenic and/or antimony, and include but is not limited to:
  • the pH stable iron(III) sulphate product formed in the abovementioned pressure leach step is composed of one or more jarosite-type minerals, such as hydronium, sodium, potassium or ammonium jarosite.
  • the pH sable iron(III) sulphate product is hydronium and/or sodium jarosite.
  • the inventors have advantageously found that the presence of additional iron compounds in the feed material subjected to the pressure leaching process also promotes the formation of copper-free secondary ferric sulphate minerals that also contain arsenic and/or antimony.
  • the molar ratio of Fe:(As+Sb) in the feed material to step (b) of the preferred embodiments described above is greater than about 1:1, and. more preferably greater than about 2:1.
  • the bulk of the arsenic and/or antimony in the feed material reports to the residue as an environmentally stable iron-arsenate and/or iron-antimonate phase, rather than as a copper-iron-sulphate-arsenate/antimonate.
  • the iron compounds suitable for the abovementioned modification to the Fe:(As+Sb) molar ratio in the feed material are such compounds that are readily solubilised under the acidic high temperature/high pressure leach conditions of the invention.
  • the particle size of the suitable iron compounds will typically be such that the solubilisation kinetics are compatible with the retention time if the high temperature/hi pressure leach stage.
  • the chemical valency of the iron compounds added to the feed material to adjust the Fe:(As+Sb) molar ratio to the required level is not thought to be critical. This is because, under the operating conditions of the high temperature/high pressure leach step (b), substantially all ferrous [Fed(II)] will be rapidly oxidised to the ferric [Fe(III)] state.
  • the iron compounds may be ferrous or ferric compounds, or mixed ferrous/ferric compounds. However, it is preferred that the iron compounds are in the ferric state since this reduces the Len consumption during the high temperature/high pressure leach step.
  • the iron compounds are derived from pyrite, in particular calcined pyrite produced under conditions that favour the formation of FeS, FeO, FeO 4 or gamma-Fe 2 O 3 over the formation of alpha-Fe 2 O 3 , since the former iron compounds are more readily solubilised compared with the latter iron compound.
  • soluble alkali metal ion salts such as those of sodium or potassium
  • the chemical agents also comprise soluble sulphate salts whose cations are merely spectator ions and as such do not participate in any precipitation reactions.
  • the preferred chemical reagents particularly include magnesium and/or zinc. Addition of a suitable soluble sulphate increases the concentration of the bisulphate ion present in the high temperature/high pressure leach slurry and decreases the effective concentration of free acid at temperature from that which would otherwise be experienced at a given feed solids composition and concentration (% solids).
  • the soluble sulphate salts may be added directly to the high temperature/high pressure leach step or generated by reacting carbonate and/or hydroxide salts of magnesium and/or zinc in the high temperature/high pressure leach step.
  • the soluble zinc salt may be introduced by the leaching of zinc sulphide minerals that may be present in the feed material.
  • the chemical reagents may also comprise bases or carbonates, in particular limestone or lime, which directly consume acid and decrease the effective concentration of free acid in the high temperature/high pressure leach step.
  • a metal value-bearing material containing arsenic and/or antimony that also constitutes a source of sulphate ions is provided for processing.
  • the metal value-bearing material may be an ore, concentrate, or any other material from which metal values, in particular copper and gold and/or silver values, may be recovered.
  • the invention is equally applicable to other metal value-bearing materials containing arsenic and/or antimony such as ores and concentrates containing other valuable metals such as nickel, cobalt, zinc and the platinum-group metals.
  • the copper-containing material is preferably a copper sulphide ore or concentrate that contains arsenic and/or antimony, and particularly applies to ores and/or concentrates that contain tennantite (Cu 12 As 4 S 13 ), enargite (Cu 3 AsS 4 ) and tetrahedrite (Cu 12 Sb 4 S 13 ), and to other ores or concentrates containing copper sulphide minerals such as, for example, chalcopyrite (CuFeS 2 ), chalcocite (Cu 2 S), bornite (Cu 5 FeS 4 ) and covellite (CuS), when contaminated with arsenic- and/or antimony-bearing material.
  • CuFeS 2 chalcopyrite
  • Cu 2 S chalcocite
  • Cu 5 FeS 4 bornite
  • CuS covellite
  • Geologically gold and/or silver are frequently associated with metal sulphide ores such as, for example, pyrite, chalcopyrite, galena, arsenopyrite and stibnite. Gold and/or silver are also often present in sulphide concentrates produced from such ores. Accordingly, a preferred embodiment of the present invention is particularly advantageous in connection with the recovery of copper and gold and/or silver from mixed gold/silver/copper ores or concentrates containing arsenic and/or antimony.
  • the metal value-bearing material is preferably a mixed gold/silver/copper ore or concentrate containing arsenic and/or antimony.
  • the mixed gold/silver/copper ore is a tennantite-enargite-calcopyrite-pyrite ore.
  • the metal value-bearing material typically undergoes comminution, flotation, blending and/or slurry formation, as well as chemical and/or physical conditioning to afford a feed stream which, in turn, is subjected to a high temperature/high pressure oxidative leach step and a series of downstream unit stages to afford recovery of the contained metal values.
  • the specific conditions applicable to the comminution, flotation and conditioning stages are determined by the chemical and physical properties of the metal value-bearing ore material. As a general rule, these specific conditions are designed to yield a concentrate that optimises recovery versus grade. These specific conditions do not have a direct bearing on the application of the preferred embodiments of the present invention. As such, the present invention is primarily concerned with the treatment of a dewatered concentrate exiting the comminution, flotation and conditioning circuits.
  • the slurry is fed to an agitated pressure vessel, preferably an autoclave, and subjected to pressure oxidation.
  • an agitated pressure vessel preferably an autoclave
  • the high temperature/high pressure leaching process is carried out at a temperature in the range of from about 180° C. to about 250° C., preferably from about 190° C. to about 230° C.
  • the optimum temperature depends on many factors including, but not limited to, the mineralogical composition of the feed, the sulphide sulphur content of the feed, the particle size distribution of the feed, and the pulp density.
  • the higher temperatures in the above ranges provide for shorter retention times and/or a reduction and/or elimination of the need for regrinding of the feed material prior to the high temperature/high pressure leach step.
  • the high temperature/high pressure leaching process is typically carried out at a total pressure sufficiently high to provide an oxygen partial pressure inside the autoclave of between about 100 kPa and about 1500 kPa, preferably in the range of from about 400 kPa to about 1000 kPa, taking into account the partial pressure of steam and other ton-condensable gases within the autoclave such as nitrogen and carbon dioxide.
  • Oxygen is typically delivered to the autoclave by bottom entry spargers entering beneath the autoclave agitators at a pressure above that inside the autoclave.
  • the autoclave agitators are designed to maximise oxygen mass transfer from the gas phase to the feed slurry.
  • Pt platinum
  • Ag/AgCl silver/silver chloride
  • Control of the ORP is achieved by limiting the rate of oxygen injection into the first compartment and more preferably approximately the first 50% of the total autoclave.
  • the high temperature/high pressure leach step is typically conducted over a period of from about 20 minutes to about 4 hours, and more preferably to about 2 hours, with higher operating temperatures and a finer feed particle size facilitating shorter reaction times.
  • reaction (1) Under the high temperature/high pressure leaching process conditions, solid metal sulphide minerals within the feed material are oxidised to the corresponding soluble metal sulphates. That is, the metal values are released into solution.
  • the actual oxidation/dissolution reactions for each metal sulphide mineral are a reflection of the chemical composition of that mineral as well as the temperature and free acidity of the leach slurry, but the overall reaction can be simplified as shown in reaction (1).
  • the arsenic and antimony components of the feed material are oxidized to the arsenate (ASO 4 3 ) and antimonite (SbO 4 3 ⁇ ) species, respectively.
  • solubilised metal values then re-precipitate within the autoclave and report to the solid phase component of the autoclave slurry as metal oxides and/or metal mixed hydroxyl-sulphates and/or metal-sulphate-arsenate-antimonate species.
  • Iron may report to the solid phase component of the autoclave slurry as one or more different iron-containing compounds during the high temperature/high pressure leach process, the identity of such phases being determined by a specific set of operating conditions. For example, the formation of basic iron sulphate is favoured by high operating temperatures and high free acid conditions. Under such conditions, the oxidation of pyrite (FeS 2 ), a significant component of many metal sulphide concentrates, can be represented by reaction (2).
  • reaction (3) The reaction of pyrite to form hematite (alpha Fe 2 O 3 ) is favoured by high temperatures and low free acidity concentrations according to reaction (3).
  • Arsenate and antimonate species formed by the oxidation of the arsenic and antimony components of the feed material may precipitate as the respective iron(III) arsenate and iron(III) antimonate phases, but may also substitute for sulphate in, for example, the jarosite phase.
  • the precipitation of arsenate as hydrated iron(III) arsenate, FeAsO 4 2H 2 O, also known as scorodite, and the partial replacement of sulphate by arsenate in various jarosite phases is well documented in the scientific literature. Jarosite is sometimes referred as a scavenger for both arsenate and antimonate.
  • the formation of hydrated iron(III) arsenate and/or arsenic-containing jarosite materials in the present invention is of considerable environmental benefit since these materials are known to be environmentally stable and can be safely discharged into and stored in conventional residue storage impoundments.
  • additional iron compounds are added to the feed material to the high temperature/high pressure leach step in order to promote the formation of jarosite rather than basic iron sulphate.
  • the jarosite phase acts as an efficient scavenger for any soluble arsenate and/or antimonate formed during the pressure oxidation reactions.
  • the jarosite phase does not itself react with lime when the gold and/or silver are recovered from the leach residue by cyanidation.
  • the total iron content of the feed material to the high temperature/high pressure leach process is such that the molar ratio of Fe:(As+Sb) is greater than about 2:1 and more preferably at least about 4:1.
  • the high Fe:(As+Sb) molar ratio reduces and/or prevents the formation and precipitation of a mixed copper-iron-arsenate-antimonate-sulphate phase
  • the iron compounds added to the metal value-bearing feed material in order to adjust the molar ratio of Fe:(As+Sb) to the desired level are of a mineral/chemical composition and particle size such that they are readily solubilised under the acidic high temperature/high pressure leach conditions.
  • the valency of the iron in the iron compounds is not thought to be critical because under the operating conditions of the high temperature/high pressure leach process, substantially all iron(II) will be oxidised to iron(III).
  • the iron compounds may be ferrous or ferric compounds or mired ferrous/ferric compounds, provided that they are soluble under the high temperature/high pressure leach conditions.
  • it is preferred that the iron compounds are pre-treated to maximise the ferric content and minimise any sulphide content in order to lower the overall oxen consumption required during the high temperature/high pressure leach step.
  • the iron compounds are derived from pyrite, in particular calcined pyrite produced by oxidative conditions with the calciner operated in such a fashion as to produce a calcined pyrite with a significant portion of the iron present in a form readily capable of being solubilised in the autoclave under the high temperature/high pressure conditions, such as for example, FeS, FeO, Fe 3 O 4 or gamma-Fe 2 O 3 , rather than alpha-Fe 2 O 3 produced in a conventional pyrite roaster, or the higher sulphide containing FeS 2 or uncalcined pyrite.
  • pyrite in particular calcined pyrite produced by oxidative conditions with the calciner operated in such a fashion as to produce a calcined pyrite with a significant portion of the iron present in a form readily capable of being solubilised in the autoclave under the high temperature/high pressure conditions, such as for example, FeS, FeO, Fe 3 O
  • the iron compounds may be sourced from recycled process solutions containing iron sulphate, preferably in the ferric form, although the process solutions may also carry minor amounts of ferrous iron as well.
  • the iron compounds may be iron-containing precipitates from various other parts of the overall process, such as the iron-containing precipitate produced during minor impurity removal ahead of or subsequent to metal value recovery steps such as copper recovery by a combination of solvent extraction and electrowinning.
  • the iron compounds may be mixed with the metal value-bearing feed stream before it is transferred to the high temperature/high pressure autoclave leach vessel, or the iron compounds may be separately transferred to the autoclave before or after introduction of the feed stream to the autoclave.
  • One of the preferred embodiments of the present invention incorporates the addition of specific chemical agents which decrease the effective. concentration of free acid generated during the high temperature/high pressure leaching process thereby affording the precipitation of pH stable iron(III) sulphate compounds and avoiding the precipitation of a basic ferric sulphate.
  • One group of chemical agents includes metal salts that directly participate in the formation of jarosite-type compounds, in particular sodium, potassium and ammonium jarosites. Such metal salts include soluble alkali metal (sodium and potassium) and ammonium sulphate.
  • the molar ratio of the added metal salt per mole of iron present in the feed should be at least 1:3 and preferably at least about 1:2, that is, an excess of metal salt above the stoichiometric requirement.
  • Another group of chemical agents that have the ability to decrease the effective concentration of free acid generated during the high temperature/high pressure leaching process comprise soluble sulphate salts whose cations are merely spectator ions and which do not participate in any precipitation reactions. Addition of soluble sulphate increases the concentration of the bisulphate ion present at the operating high temperature and decreases the effective concentration of free acid that would otherwise be expected at the given temperature, feeds solids composition and pulp density.
  • the soluble sulphate salts may be directly added to the high temperature/high pressure leaching step or generated by reacting carbonate or hydroxide salts of the appropriate metals.
  • the inventors have established that the appropriate metal sulphate salts include those of magnesium and zinc.
  • magnesium is added as magnesium carbonate (magnesite), magnesium oxide, dolomite, or mixtures thereof.
  • the soluble sulphate salts once added to or generated by the overall process, may be conveniently recycled in process water used for feed preparation and/or autoclave quench water once the copper or other dissolved metal values have been recovered from the leach solution.
  • the chemical agents may also comprise carbonates and other bases, in particular limestone and lime, which directly consume acid and decrease the effective concentration of free acid during the high temperature/high pressure leach process.
  • bases are added in an amount necessary to yield less than about 60 g/L sulphuric acid in solution in the product from the high temperature/high pressure leach step, as measured by titration of slurry samples at ambient temperature.
  • the chemical agents may be mixed with the feed stream before it is transferred to die autoclave for the high temperature/high pressure leach step, or the chemical agents may be separately transfer to the autoclave before or after introduction of the feed stream to the autoclave.
  • metal values in particular copper, may be solubilised to form a metal value-containing solution.
  • the metal values will be recovered from the metal value-containing solution by well understood methods and techniques.
  • the metal value is copper
  • copper is typically recovered from the copper-containing solution by a combination of solvent extraction and electrowinning.
  • other metal recovery processes such as cementation or precipitation of an intermediate product such as a hydroxide or sulphide could be employed.
  • the advantage of this slow cooling or digestion-conditioning step disclosed in the present invention relates to the fact that any remaining basic ferric sulphate and/or copper-iron-sulphate-arsenate-antimonate in the leach slurry will be converted into a pH stable iron(E) sulphate and/or redissolve, which in the case of copper-iron-sulphate-arsenate-antimonate will release soluble copper, respectively.
  • the lime consumption required and, in the case of copper-containing feed materials, the cyanide consumption required for gold and/or silver cyanidation should be reduced, while any copper losses to the solid leach residue should also be reduced.
  • Precious metal values such as gold and/or silver values contained in the feed material will report to the solid residue formed during the high temperature/high pressure leach process. It is envisaged that the gold and/or silver values will be recovered from the solid residue by washing to remove entrained acid and soluble metal values, repulping and treating the consequent slurry by a combination of conventional cyanidation, activated carbon, stripping, electrowinning and smelting techniques.
  • copper recoveries in excess of 95% and lime consumption of less than 15 kg/t of solid residue can be expected form a wide range of copper/gold sulphide ores and concentrates that also contain appreciable arsenic and/or antimony contents.
  • This example outlines the general scope of the preferred embodiments of the present invention as applied to the continuous processing of a run-of-mine tennantite-enargite-chalcopyrite-pyrite ore containing on average 1.5% Cu and 3.8 g/t gold derived in from the Chelopech (Bulgaria) resource.
  • a simplified flowsheet of one preferred embodiment of the present invention is shown in FIG. 1 .
  • a copper concentrate typically containing 15.5% Cu, 24.8% Fe, 38.1% S, 4.7% As and 30 g/t Au is produced by rougher, scavenger and cleaner flotation banks using the appropriate flotation reagent regime.
  • the copper concentrate is directed to a copper concentrate dewatering circuit where the free moisture is reduced to about 10%.
  • the copper concentrate is repulped in neutral barren solution (NBS) derived from the downstream copper recovery circuit (solvent extraction and electrowinning) that typically contains about 42 g/L MgSO 4 and 15 g ZnSO 4 at pH 8.5, prior to regrinding to a P 80 of 25 micron.
  • NBS neutral barren solution
  • the reground concentrate is thickened to approximately 55% solids and transferred to the agitated autoclave feed tank. To this tank are added controlled amounts of underflows from the final impurity (IR) stages of the SX raffinate and mine water treatment circuits, as well as a limestone slurry sufficient to achieve the desired carbonate-sulphur ratio in the feed.
  • IR final impurity
  • the relative amounts of limestone slurry and impurity removal underflow added to the reground concentrate are controlled to ensure that the free acidity and Fe.(As+Sb) molar ratio of the feed slurry are sufficient to prevent the precipitation of unstable basic ferric sulphate and copper-iron-sulphate-arsenate phases in the autoclave discharge slurry.
  • the solid component of the blended reground concentrate, limestone. and impurity removal slurry typically contains about 8.5% Cu, 13.1% Fe, 24.5% S, 2.7% As and 8.8 g/t Au, which is pumped into the high temperature/high pressure leach autoclave as a 45% solids slurry.
  • the combined slurry is directed to the first component of a multi-compartment high pressure autoclave fitted with a plurality of agitators by means of a centrifugal pump feeding a positive displacement, piston driven diaphragm pump at an operating pressure of over the steam saturation pressure at the operating temperature, which will generally be over 2000 kPa.
  • High pressure steam is supplied to the autoclave for initial heat-up and on as-needed basis.
  • Each compartment of the autoclave is fitted with a quench water system by which a controlled flow of quench water, typically neutral barren solution (NBS), can be directly injected into each compartment such that the desired operating temperature, typically in the range of from about 190° C. to about 230° C., is continuously maintained.
  • NBS neutral barren solution
  • the use of NBS as quench water assists with maintaining the overall process flowsheet water balance, and since it also contains appreciable magnesium and zinc sulphate contents, also assists with the control of the autoclave slurry chemistry.
  • Oxygen at 94% or greater purity is delivered from a cryogenic oxygen plant to the autoclave by bottom entry spargers entering beneath each of the autoclave agitators at a pressure greater than about 2000 kPa.
  • the bottom impeller on the agitators is of the Rushton turbine design in order to maximize oxygen mass transfer to the feed slurry.
  • the rate of oxygen injection into the first 50% of the total autoclave volume is controlled such that the Oxygen Reduction Potential (ORP), as previously defined and measured, is maintained at or below about 400 mV.
  • ORP Oxygen Reduction Potential
  • the rate of oxygen injection into the remaining 50% of the total autoclave volume. is increased so that the ORP increases to above about 500 mV to enhance the oxidation of ferrous iron to the ferric state.
  • the processed slurry is discharged from the autoclave via a single stage flash vessel at approximately 100° C. Flashed slurry flows by gravity through two agitated discharge tanks connected in series with a total retention time of about 2 hours, where the temperature is maintained at 85-100° C. From there the conditioned autoclave slurry is subjected to solid/liquid separation via a series of five conventional counter current thickeners.
  • the thickened underflow is washed to remove entrained leach solution, washed and the resultant cake forwarded to a conventional gold cyanidation circuit.
  • the final thickener overflow contains the dissolved content of the feed and is directed to a primary neutralisation (PN) circuit as pregnant leach solution (PLS).
  • PLS contains a relatively high sulphuric acid concentration, typically 30-60 g/L, excess acid is neutralised by addition of a limestone slurry to achieve a final PLS free acidity of about 2-5 g/L (pH approximately 1.5).
  • the neutralised PLS is clarified before the copper is recovered by conventional solvent extraction and electrowinning techniques.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geochemistry & Mineralogy (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US12/225,172 2006-03-28 2007-03-23 Processing of Metal Values from Concentrates Abandoned US20090293680A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AU2006901575A AU2006901575A0 (en) 2006-03-28 Improved processing of metal values from concentrates
AU2006901575 2006-03-28
PCT/AU2007/000370 WO2007109841A1 (en) 2006-03-28 2007-03-23 Improved processing of metal values from concentrates

Publications (1)

Publication Number Publication Date
US20090293680A1 true US20090293680A1 (en) 2009-12-03

Family

ID=38540713

Family Applications (1)

Application Number Title Priority Date Filing Date
US12/225,172 Abandoned US20090293680A1 (en) 2006-03-28 2007-03-23 Processing of Metal Values from Concentrates

Country Status (5)

Country Link
US (1) US20090293680A1 (de)
EP (1) EP1999284A1 (de)
AU (1) AU2007231537A1 (de)
PE (1) PE20080231A1 (de)
WO (1) WO2007109841A1 (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090019970A1 (en) * 2005-10-19 2009-01-22 Dundee Precious Metals Inc. Process for recovery of metal values from materials containing arsenic and/or antimony
WO2015058257A1 (en) * 2013-10-21 2015-04-30 Xstrata Technology Pty Ltd Leaching of minerals
US20150123030A1 (en) * 2013-11-01 2015-05-07 Colorado School Of Mines Pressure oxidation of enargite concentrates containing gold and silver
US20170009318A1 (en) * 2015-07-06 2017-01-12 Sherritt International Corporation Recovery of Copper from Arsenic-Containing Process Feed
US9885095B2 (en) 2014-01-31 2018-02-06 Goldcorp Inc. Process for separation of at least one metal sulfide from a mixed sulfide ore or concentrate
US11118244B2 (en) 2017-04-14 2021-09-14 Sherritt International Corporation Low acidity, low solids pressure oxidative leaching of sulphidic feeds
US11286540B2 (en) 2020-07-31 2022-03-29 Rio Tinto Technological Resources Inc. Method of processing a pyrite-containing slurry
US11414334B2 (en) * 2020-10-09 2022-08-16 United States Government, as represented by the Administrator of the U.S. EPA Method for sequestering ions in an environmental matrix
US11584975B1 (en) 2021-08-26 2023-02-21 Sherritt International Corporation Integrated pressure oxidative leach of copper sulphidic feed with copper heap leach
WO2024103106A1 (en) * 2022-11-14 2024-05-23 Hydromet WA Pty Limited "method for the preferential leach of value metals from sulphide concentrates"

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100307977A1 (en) * 2007-11-15 2010-12-09 Maelgwyn Mineral Services Africa (Pty) Ltd Removal of cyanide from aqueous streams
EP3286346A4 (de) 2015-04-21 2019-01-16 University of Saskatchewan Verfahren zur selektiven auslaugung und extraktion von edelmetallen in organischen lösungsmitteln
CN113151677B (zh) * 2021-04-26 2022-09-09 赣州逸豪优美科实业有限公司 一种硫酸盐无酸浸取钴中间品的方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4244734A (en) * 1979-07-19 1981-01-13 Hazen Research, Inc. Process for recovering metal values from materials containing arsenic
US5071477A (en) * 1990-05-03 1991-12-10 American Barrick Resources Corporation of Toronto Process for recovery of gold from refractory ores
US6451089B1 (en) * 2001-07-25 2002-09-17 Phelps Dodge Corporation Process for direct electrowinning of copper
US20030192404A1 (en) * 2002-04-16 2003-10-16 Cominco Engineering Services Ltd. Process for the treatment or removal of impurities in a hydrometallurgical extraction process
US20100024603A1 (en) * 2004-12-22 2010-02-04 Placer Dome Technical Services Ltd. Reduction of lime consumption when treating refractory gold ores or concentrates

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2002952490A0 (en) * 2002-11-06 2002-11-21 M.I.M. Holdings Limited Reducing cyanide consumption in gold recovery from finely ground sulphide ores and concentrates

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4244734A (en) * 1979-07-19 1981-01-13 Hazen Research, Inc. Process for recovering metal values from materials containing arsenic
US5071477A (en) * 1990-05-03 1991-12-10 American Barrick Resources Corporation of Toronto Process for recovery of gold from refractory ores
US6451089B1 (en) * 2001-07-25 2002-09-17 Phelps Dodge Corporation Process for direct electrowinning of copper
US20030192404A1 (en) * 2002-04-16 2003-10-16 Cominco Engineering Services Ltd. Process for the treatment or removal of impurities in a hydrometallurgical extraction process
US20100024603A1 (en) * 2004-12-22 2010-02-04 Placer Dome Technical Services Ltd. Reduction of lime consumption when treating refractory gold ores or concentrates

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090019970A1 (en) * 2005-10-19 2009-01-22 Dundee Precious Metals Inc. Process for recovery of metal values from materials containing arsenic and/or antimony
US10190193B2 (en) 2013-10-21 2019-01-29 Glencore Technology Pty Ltd Leaching of minerals
WO2015058257A1 (en) * 2013-10-21 2015-04-30 Xstrata Technology Pty Ltd Leaching of minerals
EA031994B1 (ru) * 2013-10-21 2019-03-29 Гленкор Текнолоджи Пти Лтд Выщелачивание минералов
AU2014339764B2 (en) * 2013-10-21 2017-10-12 Glencore Technology Pty Ltd Leaching of minerals
US11149328B2 (en) * 2013-11-01 2021-10-19 Colorado School Of Mines Method of leaching arsenic from ore comprising copper
US20150123030A1 (en) * 2013-11-01 2015-05-07 Colorado School Of Mines Pressure oxidation of enargite concentrates containing gold and silver
US9885095B2 (en) 2014-01-31 2018-02-06 Goldcorp Inc. Process for separation of at least one metal sulfide from a mixed sulfide ore or concentrate
US10370739B2 (en) 2014-01-31 2019-08-06 Goldcorp, Inc. Stabilization process for an arsenic solution
US11124857B2 (en) 2014-01-31 2021-09-21 Goldcorp Inc. Process for separation of antimony and arsenic from a leach solution
US20170009318A1 (en) * 2015-07-06 2017-01-12 Sherritt International Corporation Recovery of Copper from Arsenic-Containing Process Feed
US10544482B2 (en) * 2015-07-06 2020-01-28 Sherritt International Corporation Recovery of copper from arsenic-containing process feed
US11118244B2 (en) 2017-04-14 2021-09-14 Sherritt International Corporation Low acidity, low solids pressure oxidative leaching of sulphidic feeds
US11286540B2 (en) 2020-07-31 2022-03-29 Rio Tinto Technological Resources Inc. Method of processing a pyrite-containing slurry
US11414334B2 (en) * 2020-10-09 2022-08-16 United States Government, as represented by the Administrator of the U.S. EPA Method for sequestering ions in an environmental matrix
US11584975B1 (en) 2021-08-26 2023-02-21 Sherritt International Corporation Integrated pressure oxidative leach of copper sulphidic feed with copper heap leach
WO2024103106A1 (en) * 2022-11-14 2024-05-23 Hydromet WA Pty Limited "method for the preferential leach of value metals from sulphide concentrates"

Also Published As

Publication number Publication date
EP1999284A1 (de) 2008-12-10
WO2007109841A1 (en) 2007-10-04
PE20080231A1 (es) 2008-03-13
AU2007231537A1 (en) 2007-10-04

Similar Documents

Publication Publication Date Title
US20090293680A1 (en) Processing of Metal Values from Concentrates
US20090019970A1 (en) Process for recovery of metal values from materials containing arsenic and/or antimony
EP1931807B1 (de) Verfahren zur verarbeitung von nickelhaltigem rohmaterial bei der auf chlorid basierenden auslaugung
FI88516C (fi) Hydrometallurgiskt foerfarande foer behandling av zinksulfidhaltiga raoaemnen
US20020012621A1 (en) Process for the recovery of nickel and / or cobalt from a concentrate
US9039806B2 (en) Recycling of solids in oxidative pressure leaching of metals using halide ions
CA2470478C (en) High temperature pressure oxidation of ores and ore concentrates containing silver using controlled precipitation of sulfate species
AU2007216422A1 (en) Method for recovering copper from a copper sulphide ore
EP0574463A1 (de) Verfahren zur rückgewinnung von metall
CA2949036C (en) Hydrometallurgical process for the recovery of copper, lead and/or zinc
US11155894B2 (en) Method for reducing arsenic content in arsenic-bearing gold material
Defreyne et al. The role of iron in the CESL process
Dreisinger New developments in hydrometallurgical treatment of copper concentrates
AU2004285993B2 (en) Leach extraction method
CA3180141A1 (en) Sulphide oxidation in leaching of minerals
AU2016404384B2 (en) Hydrometallurgical method for silver recovery
AU2006303814A1 (en) Process for recovery of metal values from materials containing arsenic and/or antimony
US20230076620A1 (en) Integrated Pressure Oxidative Leach of Copper Sulphidic Feed with Copper Heap Leach
Hackl Reduction leaching of chalcopyrite

Legal Events

Date Code Title Description
STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION