US3880650A - Recovery of copper from chalcopyrite - Google Patents
Recovery of copper from chalcopyrite Download PDFInfo
- Publication number
- US3880650A US3880650A US437237A US43723774A US3880650A US 3880650 A US3880650 A US 3880650A US 437237 A US437237 A US 437237A US 43723774 A US43723774 A US 43723774A US 3880650 A US3880650 A US 3880650A
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- United States
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- set forth
- iron
- copper
- salt
- reaction product
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- 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
- C22B15/0002—Preliminary treatment
- C22B15/001—Preliminary treatment with modification of the copper constituent
- C22B15/0021—Preliminary treatment with modification of the copper constituent by reducing in gaseous or solid state
-
- 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
- C22B15/0078—Leaching or slurrying with ammoniacal solutions, e.g. ammonium hydroxide
-
- 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
- C22B15/0095—Process control or regulation methods
- C22B15/0097—Sulfur release abatement
-
- 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
- ABSTRACT Copper concentrate is mixed with iron and a fusible salt or fusiblesalt mixture which is molten at the roasting temperature.
- the mixture is roasted in a nonoxidizing atmosphere at a temperature below 475C (preferably between 350C390C) to produce a product containing free copper and pyrrhotite.
- the salt acts as a solvent for the reaction and enables copper to be recovered economically from copper concentrate without the evolution of sulfide pollutants into the atmosphere.
- the molten matte is then transferred to converters, where, in the first step of a batch operation, the iron sulfide is oxidized to yield sulfur dioxide and an iron oxide. The iron oxide is reacted with silica flux to form a slag. In a second step, the copper sulfide is oxidized to yield copper and sulfur dioxide.
- the smelting method produces sulfur containing gases which present an onerous air pollution problem.
- the process of the present invention produces copper from copper concentrates without the evolution of sulfur containing gases. Furthermore, the equipment needed to recover copper in accordance with the present invention is relatively inexpensive when compared with conventional smelting equipment.
- iron and a fusible salt or fusible salt mixture is mixed with the ore and the mixture is roasted at a temperature below 475C. As a result the copper separates from the concentrate without the evolution of sulfur containing gases.
- a further object to the present invention is to provide a process for the recovery of copper from copper concentrates which utilized equipment which is comparatively inexpensive.
- a further object of the present invention is to provide a process in which chalcopyrite is roasted to remove the sulfur without the evolution of sulfur containing gases.
- Yet another object of the present invention is to provide a process for the recovery of copper and other metals from copper concentrates which includes the step of roasting the copper concentrate with iron and a fusible salt medium at a temperature below 475C to decompose the sulfide ore in the copper concentrate and produce a reaction product containing an iron sulfide and a metal phase containing copper and other valuable metals.
- FIG. 1 is a flow chart illustrating the process of the present invention
- FIG. 2 is a graph illustrating the effect of temperature on the process of the present invention
- FIG. 3 is a graph illustrating the percent conversion of concentrate versus time
- FIG. 4 is a phase diagram of copper, sulfur and iron at 400C.
- FIG. 5 is a phase diagram of copper, sulfur and iron at 500C.
- copper concentrate is mixed with a fusible ionic salt mixture and iron and is roasted in a non-oxidizing atmosphere at a temperature below 475C.
- the mixture is roasted at a temperature between 350C and 390C.
- the product ofthe reaction is free copper and pyrrhotite (FeS).
- FeS pyrrhotite
- To insure a high yield of copper an excess amount of iron over the stoichiometric amount required is employed.
- the roasted product is quenched and fed to a magnetic separator to remove excess magnetic iron. After suitable solid-liquid separation, a floatation is performed to provide a copper product.
- the copper product is fed to a melting furnace for further refining.
- the major constituent of copper concentrate is chalcopyrite which has the formula CuFeS
- chalcopyrite which has the formula CuFeS
- a significant problem associated with the smelting of chalcopyrite is that the sulfur therein forms a sulfide gas which pollutes the atmosphere.
- no significant amount of sulfur containing gases are produced when the copper in the chalcopyrite is separated from the remainder of the compound. This separation proceeds in accordance with the following reaction:
- the molten salt acts as a solvent which enables a separation of the chalcopyrite in accordance with the following mechanism:
- the mechanism of the reaction involves an ionic diffusion process wherein chalcopyrite partially dissolves in the molten salt. Sulfide ions thus produced react with iron releasing electrons which may, in turn, reduce copper ions to copper metal.
- a molten salt solvent or catalyst enables a rapid reaction between metallic iron and chalcopyrite to directly produce metallic copper. Furthermore, because the sulfur in the chalcopyrite immediately reacts with the iron, no sulfur containing gases are emitted. Further details relative to the molten salt medium appear below.
- the process of the present invention can be advantageously employed on all known copper ores and concentrates containing copper and sulfur.
- copper concentrate is meant to include copper sulfide concentrates, whether produced from ore by flotation or produced as a sulfide matte by smelting.
- the chief ingredients of a copper-iron sulfide concentrate or matte are copper, iron and sulfur. Copper may range from 15 to 45 percent, preferably, 18 to 32 percent; iron from 15 to 40 percent, more preferably, 20 to 35 percent; and sulfur from 20 to 45 percent, more preferably, 25 to 40 percent; and the balance some gangue material, e.g. SiO A1 etc.
- the foregoing concentrates may contain small amounts of other ingredients, for example, one or more of Se, Te, Pb, Zn and such previous metals as Au, Ag, Pt and Pd.
- FIGS. 4 and 5 Two isothermal sections of a copper-iron-sulfide system are set forth in FIGS. 4 and 5.
- FIGS. 4 and 5 are taken from an article entitled Thermal Stability of Assemblages in the Cu-Fe-S System by R. A. Yund and G. Kullerud which appears in the Journal of Petrology, Vol. 7, Part 3, Page 454-488 (1966), the teachings of which are incorporated herein by reference.
- FIGS. 4 and 5 are taken from an article entitled Thermal Stability of Assemblages in the Cu-Fe-S System by R. A. Yund and G. Kullerud which appears in the Journal of Petrology, Vol. 7, Part 3, Page 454-488 (1966), the teachings of which are incorporated herein by reference.
- FIGS. 4 and 5 are taken from an article entitled Thermal Stability of Assemblages in the Cu-Fe-S System by R. A. Yund and G. Kullerud which appears in the Journal of Petrology, Vol. 7, Part
- FIG. 5 indicates that if iron is added to chalcopyrite at 500C, the chalcopyrite would be converted to bornite and pyrrhotite. Further addition of iron would not result in any additional desulfurization or conversion to metallic copper.
- FIG. 4 indicates that a major tie line change occurs between 400C and 500C.
- FIG. 4 also shows that the addition of iron to chalcopyrite or bornite will yield pyrrhotite and copper.
- concentrate 10 is conveyed by a conveyer 12 to a storage bin 14. As the concentrate is required, it is fed from storage into a hopper 16, as is shown by arrow 18. Iron is loaded into a hopper 20, as is shown by arrow 22. The fusible salt mixture is fed into a hopper 24 as is shown by arrow 26.
- Hoppers 16, 20, 24 regulate the flow of concentrate, iron and salt. These constituents can be mixed on a conveyer 28. The mixed constituents are delivered to another conveyer 30 which loads the mixed constituents into a storage hopper 32.
- a gondola 34 is positioned beneath storage hopper 32.
- the go ndola is filled with constituents from hopper 32 as is shown by arrow 36. After gondola 36 is filled, it enters a furnace 38.
- gondola 34 is part of a train. When one gondola in the train is filled, it is advanced and the next gondola in the train is positioned under hopper 32.
- the temperature of the furnace 38 is about 375C and a loaded gondola is in the furnace for about one hour.
- the reaction product in the gondolas are dumped into a well 40.
- the reaction product is quenched by water which is flowed into well 40 and is agitated by a mixer to produce a slurry which is withdrawn as is shown by arrow 44.
- the water also dissolves the salt.
- the slurry contains particles of copper, iron, iron sulfide and gangue.
- the slurry from well 40 is delivered to a magnetic separator 46.
- the magnetic separator 46 removes metallic iron present in excess of the stoichiometric amount from the slurry. This iron is then recycled along route 48 and is also fed into hopper 20.
- the slurry leaving the magnetic separator 46 is fed into a countercurrent decantation wash system 50 (CCD wash) as is shown by arrow 52.
- CCD wash countercurrent decantation wash system 50
- vessel 54 the solids are separated from the remainder of the salt water solution and are passed into vessel 56.
- the salt water solution is withdrawn from vessel 54 and is delivered to a salt pond as is shown by arrow 58.
- the salt pond the water is evaporated to produce salt for a recycle. Recovered salt is recycled along route to hopper 24.
- the metal values are delivered into another wash vessel 62. After being washed in vessel 62, the metal values are delivered to a floatation cell 64. Fresh water is introduced into vessel 62, is flowed counter-current to the solids into vessel 56 as is shown by arrow 66. After flowing through vessel 56, the water is flowed into well 40 to be used to quench the reaction product as is shown by arrow 68.
- the metal values recovered from vessel 62 as is shown by arrow 70 can be recovered in any conventional manner.
- the metal values may be recovered in a floatation cell.
- the metal values (principally copper) are sent to a melting furnace and then to electro refining as is shown by arrow 72.
- the tailings which consist mainly of FeS go to a waste dump.
- the process of the present invention involves the separation of sulfur from copper sulfide ores without the evolution of sulfur containing gases.
- the sulfur is separated from the copper in a molten salt medium.
- the molten salt acts as a solvent for the constituents in the chemical reaction or in a broader sense as a catalyst for the reaction.
- Many salts and mixtures of salts can be advantageously employed in the process of the present invention as the solvent for the reaction.
- the requirements of the solvent are that it possesses the following properties:
- the fine particulate iron is readily available from a number of commercial sources. Ungraded 200 mesh iron powder of the type commonly used for coating welding rods can be advantageously employed in the process of the present invention.
- non-oxidizing atmosphere means an atmosphere in which metallic iron will not be oxidized. At the temperature range employed in this process. this is equivalent to maintaining the oxygen partial pressure below a value of l0' atm. This may be achieved by utilizing any of a number of so-called reducing gases commonly used in industry in annealing and other similar operations. Typically, these are produced by incomplete combustion of any fuel materials such as oil, coal, natural gas or propane. Those skilled in the art are well familiar with such techniques.
- FIG. 2 shows that the effect of temperature on the percent conversion under identical conditions of feed material and time.
- a 200 mesh concentrate having the composition set forth in Table I below was reacted with -200 mesh iron and a 44 weight percent LiCl 56 weight percent KCl eutectic. The reaction time and feed rate were fixed.
- Reaction rates peak over about a 40 temperature range from 350C to 390C.
- the rate is believed to fall off at higher temperatures due to the approach of the tie line change wherein copper metal would no longer be in thermodynamic equilibrium with pyrrhotite.
- the falloff on the low side is believed to be due to the normal decreases of rate with temperature and/or changes in the solubility of the minerals in the fused salt with temperature.
- FIG. 3 shows a plot of the percent conversion of concentrate versus time at 375C using 200 mesh iron, a 44 weight percent LiCl- 56 weight percent KCI eutectic, and a 200 mesh concentrate having the composition set forth in Table I below.
- the reaction product is a fine dispersion of whiskerlike copper in a mixture of FeS, gangue minerals, and excess iron.
- Mass spectographic analysis of impurities in copper produced by conversion of concentrate indicates a purity level of 99.90 percent copper exclusive of silver and gold.
- the results in parts per million by weight (ppm W) are presented in the Table II below.
- Copper may be readily leached from the reaction product, using ammonia-CO solutions. With a 0.6M CO M NI-I aqueous solution, 95 percent of the converted copper is leached out within 15 minutes.
- copper can be recovered from the reaction product by leaching and electrowinning. This is advantageously accomplished by leaching with aerated ammonia-ammonium carbonate solutions and subsequently electrowinning.
- Atomic absorption analysis of the copper metal and original concentrate indicate that all of the silver and gold report to the copper, while all the molybdenum remains with the pyrrhotite.
- the product could therefore be electrorefined to reclaim precious metals.
- EXAMPLE l Referring to FIG. 1, 647 tons per day of 200 mesh copper concentrate is loaded into hopper 16.
- the concentrate has the average composition as set forth in Table 1 above.
- l92 tons per day of iron and 40 tons per day of salt is introduced into hopper 20 and 24 respecively.
- the iron added into hopper 20 is 200 mesh iron.
- the salt is a eutectic mixture of 55 weight percent MgCl 25 weight percent NaCl and 20 weight percent KCl.
- the concentrate, iron, and salt is batch heated in a furnace at a temperature of 390C for 1 hour.
- a commercial fuel such as coal or oil is incompletely combusted.
- the reaction product is quenched with water to form a slurry.
- the slurry is then passed through a magnetic separator to remove excess iron.
- 42 tons per day of iron is recycled back to hopper 20 from the magnetic separator.
- the slurry is subjected to a countercurrent decantation wash. in which the salt water solution is withdrawn from the remaining solid particles. The water is evaporated to leave dry salt.
- 360 tons per day of recycled salt is fed into hopper 24 along with the salt make up.
- the water required in the countercurrent decantation wash is about 43,000 gallons per day. After floatation, about l5l.8 tons of copper per day is withdrawn from the melting furnace.
- a process for recovering copper from a concentrate containing copper and sulfur comprising the following steps:
- step (a) roasting the mixture of step (a) at a temperature below 475C to produce a reaction product containing elemental copper and pyrrhotite;
- step (b) 2. The process as set forth in claim 1 wherein the roasting which takes place in step (b) is performed in a non-oxidizing atmosphere.
- step (a) an excess amount of iron over the stoichiometric amount required is mixed with the concentrate and salt.
- reaction product is quenched in water to dissolve the ionic salt and produce a slurry.
- the process as set forth in claim 4 also including the step of feeding the reaction product to a magnetic separator to remove magnetic iron from the reaction product.
- step (c) the copper is separated from the iron by floatation.
- step (b) the mixture is roasted at a temperature of between about 350C and 390C for one hour.
- step (a) 11. The process as set forth in claim 10 wherein water and dissolved ionic salt are withdrawn from the slurry to leave solids and the ionic salt is recovered and recycled to be mixed with the concentrate and iron in step (a).
- step (a) the ionic salt that is mixed with the iron and concentrate has the following properties:
- step (b) the mixture is roasted at a temperature between the range of 350C390C.
- step (a) The process as is set forth in claim wherein the iron that is mixed with the concentrate and ionic salt in step (a) is particulated to a size of about -200 mesh.
- step (c) the copper is separated from the reaction product by leaching the reaction product with an ammonia ammonium carbonate solution and subsequently electrowinning the copper.
- a process for recovering copper from a material containing copper and sulfur, the material including a member selected from the group consisting of chalcopyrite, bornite, chalcocite, covellite, pyrite, cubanite and idaite comprising the following steps:
- step (b) roasting the mixture of step (a) at a temperature below 475C to partially dissolve the material into the salt and to produce a reaction product containing elemental copper and pyrrhotite, said salt acting as a solvent enabling the reduction of copper by iron to occur below 475C without the evolution of sulfide pollutants into the atmosphere, and
- step (b) The process as set forth in claim 24 wherein the roasting which takes place in step (b) is performed in a non-oxidizing atmosphere.
- step (a) an excess amount of iron over the stoichiometric amount required is mixed with the material and salt.
- the process as set forth in claim 27 also including the step of feeding the reaction product ,to a magnetic separator to remove magnetic iron from the reaction product.
- step (c) the copper is separated from the iron by floatation.
- step (b) the mixture is roasted at a temperature of between about 350C and 390C for one hour.
- step (b) the mixture is roasted at a temperature between the range of 350C390C.
- step (a) The process as set forth in claim 43 wherein the iron that is mixed with the material and ionic salt in step (a) is particulated to a size of about 200 mesh.
- step (c) the copper is separated from the reaction product by leaching the reaction product with an ammonia ammonium carbonate solution and subsequently electrowinning the copper.
Abstract
Description
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Application Number | Priority Date | Filing Date | Title |
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US437237A US3880650A (en) | 1974-01-28 | 1974-01-28 | Recovery of copper from chalcopyrite |
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US437237A US3880650A (en) | 1974-01-28 | 1974-01-28 | Recovery of copper from chalcopyrite |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4110106A (en) * | 1976-02-13 | 1978-08-29 | Kennecott Copper Corporation | Selective sulfation process for partitioning ferrous and non-ferrous values in an ore |
US4149880A (en) * | 1978-07-19 | 1979-04-17 | Kennecott Copper Corporation | Recovery of copper from arsenic containing metallurgical waste materials |
US5074910A (en) * | 1987-11-23 | 1991-12-24 | Chevron Research And Technology Company | Process for recovering precious metals from sulfide ores |
US5104445A (en) * | 1987-07-31 | 1992-04-14 | Chevron Research & Technology Co. | Process for recovering metals from refractory ores |
US5849172A (en) * | 1997-06-25 | 1998-12-15 | Asarco Incorporated | Copper solvent extraction and electrowinning process |
US20110058997A1 (en) * | 2008-05-13 | 2011-03-10 | Salt Extraction Aktiebolag | process for chlorinating resources containing recoverable metals |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3681055A (en) * | 1969-04-21 | 1972-08-01 | American Refining Ltd | Copper recovery process |
US3761245A (en) * | 1970-01-09 | 1973-09-25 | Stone & Webster Eng Corp | Nickel segregation process using metallic iron as reductant |
US3799764A (en) * | 1971-01-25 | 1974-03-26 | American Metal Climax Inc | Roasting of copper sulfide concentrates combined with solid state segregation reduction to recover copper |
-
1974
- 1974-01-28 US US437237A patent/US3880650A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3681055A (en) * | 1969-04-21 | 1972-08-01 | American Refining Ltd | Copper recovery process |
US3761245A (en) * | 1970-01-09 | 1973-09-25 | Stone & Webster Eng Corp | Nickel segregation process using metallic iron as reductant |
US3799764A (en) * | 1971-01-25 | 1974-03-26 | American Metal Climax Inc | Roasting of copper sulfide concentrates combined with solid state segregation reduction to recover copper |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4110106A (en) * | 1976-02-13 | 1978-08-29 | Kennecott Copper Corporation | Selective sulfation process for partitioning ferrous and non-ferrous values in an ore |
US4149880A (en) * | 1978-07-19 | 1979-04-17 | Kennecott Copper Corporation | Recovery of copper from arsenic containing metallurgical waste materials |
US5104445A (en) * | 1987-07-31 | 1992-04-14 | Chevron Research & Technology Co. | Process for recovering metals from refractory ores |
US5074910A (en) * | 1987-11-23 | 1991-12-24 | Chevron Research And Technology Company | Process for recovering precious metals from sulfide ores |
US5849172A (en) * | 1997-06-25 | 1998-12-15 | Asarco Incorporated | Copper solvent extraction and electrowinning process |
US20110058997A1 (en) * | 2008-05-13 | 2011-03-10 | Salt Extraction Aktiebolag | process for chlorinating resources containing recoverable metals |
US8470271B2 (en) * | 2008-05-13 | 2013-06-25 | Salt Extraction Aktiebolag | Process for chlorinating resources containing recoverable metals |
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Legal Events
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AS | Assignment |
Owner name: KENNECOTT MINING CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:KENNECOTT CORPORATION;REEL/FRAME:004815/0036 Effective date: 19870220 Owner name: KENNECOTT CORPORATION, 200 PUBLIC SQUARE, CLEVELAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KENNECOTT MINING CORPORATION;REEL/FRAME:004815/0063 Effective date: 19870320 Owner name: KENNECOTT CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:KENNECOTT COPPER CORPORATION;REEL/FRAME:004815/0016 Effective date: 19800520 |
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Owner name: GAZELLE CORPORATION, C/O CT CORPORATION SYSTEMS, C Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:RENNECOTT CORPORATION, A DE. CORP.;REEL/FRAME:005164/0153 Effective date: 19890628 |
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Owner name: KENNECOTT UTAH COPPER CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:GAZELLE CORPORATION;REEL/FRAME:005604/0237 Effective date: 19890630 |