WO1997028288A1 - Oxygen smelting of copper and/or nickel sulphide ore concentrates - Google Patents
Oxygen smelting of copper and/or nickel sulphide ore concentrates Download PDFInfo
- Publication number
- WO1997028288A1 WO1997028288A1 PCT/GB1997/000275 GB9700275W WO9728288A1 WO 1997028288 A1 WO1997028288 A1 WO 1997028288A1 GB 9700275 W GB9700275 W GB 9700275W WO 9728288 A1 WO9728288 A1 WO 9728288A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- oxygen
- sulphur
- metal
- oxidation
- sulphur dioxide
- Prior art date
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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
- C22B15/00—Obtaining copper
- C22B15/0026—Pyrometallurgy
- C22B15/0028—Smelting or converting
- C22B15/003—Bath smelting or converting
-
- 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
- C22B15/0026—Pyrometallurgy
- C22B15/0028—Smelting or converting
- C22B15/005—Smelting or converting in a succession of furnaces
-
- 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
- C22B23/00—Obtaining nickel or cobalt
- C22B23/02—Obtaining nickel or cobalt by dry processes
- C22B23/025—Obtaining nickel or cobalt by dry processes with formation of a matte or by matte refining or converting into nickel or cobalt, e.g. by the Oxford process
Definitions
- This invention relates to smelting, and is more particularly, but not exclusively, concerned with the oxygen smelting of copper sulphide ore concentrates, nickel sulphide ore concentrates or bulk copper and nickel sulphide ore concentrates (hereinafter referred to simply as “copper and/or nickel sulphide ore concentrates”) of high intrinsic energy value.
- the product of smelting an ore concentrate in both copper and nickel smelting may be a low-iron high grade matte (sometimes referred to as "white metal” in copper smelting if the iron content is exceedingly low) or alternatively, a crude metal containing various levels of sulphur and oxygen, which in the case of copper is referred to as "blister copper or "semi-blister".
- blister copper a crude metal containing various levels of sulphur and oxygen
- the normal product is a furnace matte containing relatively large amounts of iron sulphide. If the iron is reduced to a low level it is sometimes referred to as "Bessemer matte".
- the iron is reduced to a low level it is sometimes referred to as "Bessemer matte".
- the invention relates equally well to solid sulphide process intermediates, such as granulated and ground low-iron matte of similar physical properties and chemical composition to a low-iron copper ore concentrate or analogous low-iron nickel sulphide material.
- W093/24666 whose subject matter is incorporated herein by reference, discloses an oxygen smelting procedure where the copper and/or nickel sulphide ore concentrate of high intrinsic energy value is oxygen smelted by forcibly circulating a molten sulphide carrier composition through a closed loop extraction circuit from which at least one product selected from copper, nickel and sulphides thereof can be continuously extracted at an elevated temperature, introducing the ore concentrate into the molten carrier composition at an ore receiving station so that the ore is dissolved in or melted by the composition, contacting the molten carrier composition containing said ore with an oxidising gas containing at least 30 volume percent oxygen at an oxidation station so as to oxidise at least part of the ore and/or the molten carrier composition, and utilising heat generated during the oxidation step as a result of oxidation of the ore concentrate.
- the oxidising gas is preferably technically pure oxygen and the heat generated during the oxidation step is utilised either by smelting the copper/nickel sulphide ore concentrate of high intrinsic energy value with another mineral concentrate of low or negative intrinsic energy value or by reducing iron oxide in slag produced in the method to a liquid iron product, and recovering such liquid iron product.
- oxygen i.e. oxygen of commercial purity (95% or higher) or oxygen enriched air as opposed to air has the advantage that it is not necessary to treat large quantities of nitrogen to remove entrained pollutants such as oxides of nitrogen, oxides of sulphur and volatiles such as arsenic, antimony and bismuth before discharge.
- WO 93/24666 describes a procedure where sulphur dioxide produced during the oxidation of the ore concentrate and any excess unreacted oxygen are passed to a sulphuric acid production unit, the separated oxygen being recycled back to lances used in the oxidation step to be mixed with fresh technically pure oxygen.
- the present invention is not only applicable to a modification of the procedure described in WO 93/24666, but is also applicable to the enriched oxygen smelting of high intrinsic energy copper and/or nickel sulphide ore concentrates using existing bath and flash smelting operations, and indeed the sulphidic process intermediates already referred to, such as granulated and ground low-iron matte.
- a process of smelting a metal (preferably copper and/or nickel) sulphide ore concentrate, or similar material, of high intrinsic energy comprising the steps of exothermically reacting the metal sulphide material with oxygen in an oxidation station to produce the metal, or a low-iron matte, and sulphur dioxide; and recovering said metal or low-iron matte; wherein (a) sulphur dioxide removed from the oxidation station is oxidised with oxygen externally of said oxidation station to form sulphur trioxide, (b) the sulphur trioxide and further oxygen is passed to the oxidation station, and (c) in said reacting step in the oxidation station, at least some of the sulphur trioxide is endothermically dissociated to form sulphur dioxide and oxygen so as to absorb at least some of the exothermic heat resulting from reaction of the metal sulphide material with the oxygen
- At least 99 percent pure oxygen is supplied to the process. In such a case precautions will be taken to avoid ingress of air.
- the only gas eventually discharged or bled from the system will be equivalent to the nitrogen in combined gases 50 2 /0 2 /N 2 having a nitrogen content equivalent to the nitrogen arising from the very small amount of nitrogen impurity in the high quality tonnage oxygen provided, which can be scrubbed chemically clean.
- the exothermic reaction step is effected in the presence of an excess amount of oxygen so that unreacted oxygen leaves the oxidation station with the sulphur dioxide.
- some of the sulphur dioxide and oxygen removed from the oxidation station are reacted with an alkaline earth metal compound eg calcium oxide derived from dolomite or limestone, in a sulphation reactor to form an alkaline earth metal sulphate, the remaining sulphur dioxide being subjected to said oxidation to sulphur trioxide.
- an alkaline earth metal compound eg calcium oxide derived from dolomite or limestone
- the process of the present invention is most preferably applied to a smelting process involving forcibly circulating a molten sulphide carrier composition through a closed loop extraction circuit from which said metal can be continuously extracted at an elevated temperature, said closed loop extraction circuit including said oxidation station and a receiving station; and introducing the metal sulphide material into the molten carrier composition at said receiving station so that the metal sulphide material is dissolved in or melted by the composition and is passed to said oxidation station.
- Such process may be of the type disclosed in WO 93/24666 but where, instead of utilising the exothermic heat by (a) co-smelting a high intrinsic energy ore concentrate with an ore of low intrinsic energy or (b) converting iron in an ore concentrate to metallic iron, the exothermic heat is absorbed at least partly by the above-mentioned endothermic dissociation of sulphur trioxide.
- Fig 1 is a flow diagram showing an embodiment of the present invention, wherein a chalcopyritic ore concentrate is smelted using technically pure oxygen in a closed loop gas recirculation mode, in association with a closed loop melt circulation extraction circuit
- Fig 2 is a flow diagram of an embodiment of the present invention wherein a clean copper concentrate is smelted with technically pure oxygen in a flash smelter, cyclone smelter, bath smelter or other established smelting process referred to hereafter as a primary smelter, using technically pure oxygen in a closed loop gas circulation mode.
- a primary closed loop extraction circuit for a molten carrier material (matte) of copper sulphide is established through first and second refractory hearths 10 and 12 by means of an R-H degassing unit 14 having an inlet snorkel 16 extending into the molten matte in a slag separation zone 17 of the first hearth 10 and an outlet snorkel 18 which supplies molten matte into the second hearth 12.
- the slag separation zone 1 7 is connected with the remainder of the first hearth 10 by an overflow weir 19 for matte and slag.
- Molten matte circulates back to the first hearth 10 from the second hearth 12 via a connecting passage 20, which is effectively an overflow attached to hearth 12 but free to move with respect to the first hearth 10.
- the passage 20 is fitted with means such as a labyrinth seal 21 for preventing the gases in the respective hearths 10 and 12 from intermixing.
- the first hearth 10 is lower than the second hearth 12.
- Pelletised chalcopyritic ore concentrate is passed via multiport feeds 24 into either side of the first hearth 10 of the primary smelting circuit.
- the ore concentrate moves down sloping side walls of the first hearth 10 for a substantial distance as a relatively thin layer before entering the layer of molten matte which is moving at high rate through the first hearth 10.
- the first hearth 10 defines an ore receiving station.
- the pellets of ore concentrate are exposed to radiant heat within the first hearth 10 which, like the other hearth 12, is rendered substantially gas tight by a refractory roof.
- the ore concentrate may be transported using a heat-resistant belt conveyor within the high temperature region of the hearth, which takes the concentrate along the entire length of the hearth 10 before discharge into the circulating molten matte.
- the ore concentrate is thereby heated to a temperature of about 1000 K, at which temperature labile sulphur is volatilised as sulphur vapour and arsenic and antimony, present as impurities in the ore concentrate, are also volatilised in the form of their sulphides.
- Such vapours are removed from first hearth 10 via line 26 leading to a condenser (not shown).
- the matte is then transferred to the second hearth 12 through the R- H degassing unit 14. Since the inlet snorkel 16 extends below the layer of slag which has formed on top of the molten matte layer M, relatively clean matte is transferred to the second hearth 12 by the R-H unit 14. Slag is removed and passed either to a conventional slag granulation system employing water, or via path 28 for dry granulation.
- the molten matte transferred to the second hearth 12 of the primary smelting circuit and which contains the dissolved ore concentrate is then subjected to oxidation at an oxidation station 29 using technically pure oxygen in admixture with sulphur dioxide and sulphur trioxide supplied via line 30 to top blow nozzles 32.
- Top blowing is controlled so as to convert the copper sulphide to copper metal.
- the oxygen utilisation efficiency is arranged so that gases which exit from the oxidation station 29 via a line 36 contain excess oxygen, sulphur dioxide and a reduced amount of undissociated sulphur trioxide.
- the copper produced is bled off via line 34 as blister copper whilst the matte layer passes back to the first hearth 10 via passage 20.
- An in situ slag cleaning operation (eg using iron pyrites) is effected at this location in hearths 10 and 12.
- the gases exiting from the oxidation station 29 via line 36 pass into a fluidised bed 38 containing preheated (1200 K) silica sand flux which is fluidised by such gases. Slag may be passed from path 28 into the bed 38 to be dry granulated therein and discharged via line 40. The gases are de-fumed by agglomeration of fume on the bed of sand and leave the bed 38 to enter a sulphation reactor 42.
- the solid product of this pre-treatment of virtually pure sulphur dioxide would comprise calcium arsenate and calcium halides which can be readily separated, with the calcium arsenate being an ideal material for incorporation into a vitreous slag matrix.
- This is conveniently done by assimilating calcium arsenate into the fayalite slag produced in the smelter. Provided the slag is water-quenched, it can be expected to pass strict environmental regulations such as leachability tests .
- dolomite is calcined to form calcium oxide which then reacts with a proportion of the sulphur dioxide and oxygen to form anhydrite which is removed as a product.
- the sulphation reactor 42 and calciner are preferably of the type disclosed in British Patent Application No. 9602037.5.
- the gases (oxygen, unreacted sulphur dioxide and some sulphur trioxide) are passed to a fluid bed HRSG 44, in which the sulphur dioxide is reacted with some of the oxygen to form sulphur trioxide.
- a fluid bed of a chrome-ferric oxide mineral such as chromite fines at, for example 950 K is operated under near equilibrium conditions to produce a gas mixture containing 1 mol S0 3 , 0.54 mol 0 2 and 0.50 mol S0 2
- a gas mixture can be used to cool down a flash smelter operating with chalcopyrite to produce liquid copper without overheating.
- both at room temperature would require approximately twice the molar gas flow rate at the entrance to the flash smelter reaction shaft.
- dust carry over a recognised problem in both bath smelting and flash smelting, is reduced when a lower gas volume is used.
- a lower gas volume also proportionately reduces downstream gas cleaning requirements, reflected in decreases both in capital and operating costs.
- a reduction in volume both within the smelting bath and exiting from the reactor helps reduce excessive splashing, foaming and what is known as "slopping".
- the resultant gas mixture leaving the HRSG 44 is passed to a hot gas eductor 46.
- the gases are mixed with technically pure oxygen and the resultant mixture passed via line 30 to the nozzles 32.
- a relatively static or slow-moving layer of molten copper is maintained in the hearths 10 and 12 below the rapidly circulating molten matte so as to protect the hearths against severe erosion which would otherwise occur if the circulating matte were directly in contact with the hearth.
- Reaction (a) takes place under neutral or reducing conditions so that one quarter of the sulphur contained in chalcopyrite is recovered in the elemental form, whilst three quarters is released as S0 2 .
- the overall heat balance for the circuit is given in Table 1.
- the outlet gas temperature of 1200 K is based on heat and mass transfer correlations for top blowing in a non-splash mode.
- TOTAL ENTHALPY OUT 10,399 To effectively capture the excess energy released by smelting of the ore concentrate, use is made of the endothermic dissociation of sulphur trioxide in the recirculated gas. This can be effected by restricting the cooling of gases before recirculation only down to about 900 K within the HRSG 44 or similar device, in which the exothermic recombination of 0 2 and S0 2 is facilitated and the energy recovered initially from within the smelting furnace and supplemented further in the sulphation reactor 42 appears eventually as steam for electricity generation.
- a primary smelter 48 in which excessive heat generated over and above the basic requirements of smelting a sulphidic material to either a high grade matte or metal, is removed by circulating a gas principally comprising S0 3 /S0 2 /0 2 and residual N 2 via a line 50 to a reaction shaft, cyclone reactor, top blown lance(s) or submerged tuyeres (not shown) of the primary smelter 48.
- the return of fume and particulates to the smelter 48 is an essential requirement so gases are passed to a hot gas cleanup station 54 to effect the desired solid/gas separation.
- Hot gas cleaning is a rapidly expanding field, particularly in advanced power generation, where candle ceramic filters and moving granular bed filters, for example, are under intense development for removing particulates at high temperature from fuel gas prior to its combustion in gas turbines. More conventionally, the hot gas cleanup station 54 would partially cool the gases in a waste heat boiler followed by a hot gas precipitator. The principal gas flow is passed without further cooling via a line 56 to eductors 58 activated with high pressure oxygen from an air separation plant (not shown).
- HRSG Heat Recovery Steam Generator
- S0 2 and 0 2 may also be added to HRSG 62 via a line 64, or alternatively directly back to the smelter 48 via a line 66.
- an amount of S0 2 equivalent to the sulphur in the feed sulphidic material to the smelter 48 is removed from the principal gas recirculation system via a line 68.
- line 68 may be connected with a conventional sulphuric acid production plant 70 wherein the gases in line 68 are cooled and extensively cleaned. It is of concern in current smelting technology, if extra S0 3 enters the acid plant 70 upstream of the catalytic converters.
- this 2.75 mol of 0 2 is more than adequate to recirculate 0.05 mol 0 2 , 1.60 mol S0 2 and 1.40 mol S0 3 at 900 K back to the top blow nozzles 32 in the oxidation station 29.
- the 0 2 /S0 2 /S0 3 gas mixture is essentially at equilibrium at 900 K as it leaves the HRSG 44 and the effect of the cold oxygen addition is to lower the temperature of the recycled gas stream to about 710 K.
- the gas composition entering the oxidation station 29 principally reflects dilution with oxygen rather than a significant increase in the mols of S0 3 .
- the gas discharging from the top blow nozzles 32 thus contains 2.80 mol 0 2 , 1.60 mol S0 2 and 1.4 mol S0 3 .
- oxygen utilisation efficiency in the top blow region can be arranged so that the gases exiting from the smelter at say 1200 K contain 1.25 mol 0 2 4.00 mol S0 2 and 0.5 mol S0 3 , again essentially in an equilibrium state.
- the endothermic dissociation of 0.9 mol S0 3 within the oxidation station 29 performs the useful task of removing a significant proportion of the excess heat generated when chalcopyrite is contacted with oxygen.
- 1.5 mol S0 2 and 0.75 mol 0 2 are removed and, if they exit at say 1400 K, very little S0 3 remains and the gases directed to the HRSG 44 contain 3 mol S0 2 and 0.75 mol 0 2 .
- some 1.40 mol S0 3 are formed as the gas mixture cools from 1400 K to 900 K releasing exothermic heat far in excess of that associated with the sensible heat change in the absence of chemical reaction.
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Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97901733A EP0877829A1 (en) | 1996-02-01 | 1997-01-30 | Oxygen smelting of copper and/or nickel sulphide ore concentrates |
AU15538/97A AU705242B2 (en) | 1996-02-01 | 1997-01-30 | Oxygen smelting of copper and/or nickel sulphide ore concentrates |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9602036.7A GB9602036D0 (en) | 1996-02-01 | 1996-02-01 | Smelting |
GB9602036.7 | 1996-02-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997028288A1 true WO1997028288A1 (en) | 1997-08-07 |
Family
ID=10787944
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1997/000275 WO1997028288A1 (en) | 1996-02-01 | 1997-01-30 | Oxygen smelting of copper and/or nickel sulphide ore concentrates |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0877829A1 (en) |
AU (1) | AU705242B2 (en) |
GB (1) | GB9602036D0 (en) |
WO (1) | WO1997028288A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8671688B2 (en) | 2011-04-13 | 2014-03-18 | General Electric Company | Combined cycle power plant with thermal load reduction system |
US9222410B2 (en) | 2011-04-13 | 2015-12-29 | General Electric Company | Power plant |
WO2018083434A1 (en) * | 2016-11-07 | 2018-05-11 | Warner, Noel A. | Carbon-free smelting of hematite ore |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0016595A1 (en) * | 1979-03-09 | 1980-10-01 | National Research Development Corporation | A method of recovering non-ferrous metals from their sulphide ores |
US4802917A (en) * | 1985-03-20 | 1989-02-07 | Inco Limited | Copper smelting with calcareous flux |
WO1993024666A1 (en) * | 1992-05-23 | 1993-12-09 | The University Of Birmingham | Oxygen smelting |
-
1996
- 1996-02-01 GB GBGB9602036.7A patent/GB9602036D0/en active Pending
-
1997
- 1997-01-30 EP EP97901733A patent/EP0877829A1/en not_active Withdrawn
- 1997-01-30 AU AU15538/97A patent/AU705242B2/en not_active Ceased
- 1997-01-30 WO PCT/GB1997/000275 patent/WO1997028288A1/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0016595A1 (en) * | 1979-03-09 | 1980-10-01 | National Research Development Corporation | A method of recovering non-ferrous metals from their sulphide ores |
US4802917A (en) * | 1985-03-20 | 1989-02-07 | Inco Limited | Copper smelting with calcareous flux |
WO1993024666A1 (en) * | 1992-05-23 | 1993-12-09 | The University Of Birmingham | Oxygen smelting |
Non-Patent Citations (1)
Title |
---|
NICKOLAS J. THEMELIS: "Pyrometallurgy near the end of the 20th century", JOM, vol. 46, no. 8, August 1994 (1994-08-01), WARRENDALE, PA, USA, pages 51 - 57, XP000461899 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8671688B2 (en) | 2011-04-13 | 2014-03-18 | General Electric Company | Combined cycle power plant with thermal load reduction system |
US9222410B2 (en) | 2011-04-13 | 2015-12-29 | General Electric Company | Power plant |
WO2018083434A1 (en) * | 2016-11-07 | 2018-05-11 | Warner, Noel A. | Carbon-free smelting of hematite ore |
Also Published As
Publication number | Publication date |
---|---|
AU705242B2 (en) | 1999-05-20 |
GB9602036D0 (en) | 1996-04-03 |
AU1553897A (en) | 1997-08-22 |
EP0877829A1 (en) | 1998-11-18 |
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