US20160355905A1 - Method for treating sulfide-free minerals - Google Patents
Method for treating sulfide-free minerals Download PDFInfo
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- US20160355905A1 US20160355905A1 US15/101,431 US201315101431A US2016355905A1 US 20160355905 A1 US20160355905 A1 US 20160355905A1 US 201315101431 A US201315101431 A US 201315101431A US 2016355905 A1 US2016355905 A1 US 2016355905A1
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- sulfide
- free
- metal oxide
- sulfatization
- concentrate
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- 238000000034 method Methods 0.000 title claims abstract description 66
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims abstract description 40
- 239000011707 mineral Substances 0.000 title claims abstract description 40
- 229910052751 metal Inorganic materials 0.000 claims abstract description 37
- 239000002184 metal Substances 0.000 claims abstract description 37
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 36
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 36
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 28
- 239000012141 concentrate Substances 0.000 claims abstract description 28
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 claims description 143
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 68
- 239000007787 solid Substances 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 12
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 229910052717 sulfur Inorganic materials 0.000 claims description 10
- 239000011593 sulfur Substances 0.000 claims description 10
- 238000011065 in-situ storage Methods 0.000 claims description 8
- 238000002386 leaching Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 5
- 229910021540 colemanite Inorganic materials 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052770 Uranium Inorganic materials 0.000 claims description 3
- 229910001730 borate mineral Inorganic materials 0.000 claims description 3
- 239000010429 borate mineral Substances 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910021537 Kernite Inorganic materials 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 229910052787 antimony Inorganic materials 0.000 claims description 2
- 229910052797 bismuth Inorganic materials 0.000 claims description 2
- 229910021538 borax Inorganic materials 0.000 claims description 2
- 229910052793 cadmium Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 150000004679 hydroxides Chemical class 0.000 claims description 2
- 229910052738 indium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 150000004760 silicates Chemical class 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004328 sodium tetraborate Substances 0.000 claims description 2
- 235000010339 sodium tetraborate Nutrition 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 229910021539 ulexite Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 235000013980 iron oxide Nutrition 0.000 claims 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 claims 1
- 239000007789 gas Substances 0.000 description 55
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 27
- 238000006243 chemical reaction Methods 0.000 description 20
- 238000004519 manufacturing process Methods 0.000 description 15
- 230000003197 catalytic effect Effects 0.000 description 12
- 239000003795 chemical substances by application Substances 0.000 description 11
- 150000002739 metals Chemical class 0.000 description 9
- 238000002485 combustion reaction Methods 0.000 description 8
- 239000012043 crude product Substances 0.000 description 7
- 238000011084 recovery Methods 0.000 description 7
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 3
- 229910052810 boron oxide Inorganic materials 0.000 description 3
- 238000005243 fluidization Methods 0.000 description 3
- 229910000358 iron sulfate Inorganic materials 0.000 description 3
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 3
- 239000002918 waste heat Substances 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 2
- 239000003570 air Substances 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 150000001639 boron compounds Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011143 downstream manufacturing Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- GTUNMKRGRHOANR-UHFFFAOYSA-N [B].[Ca] Chemical class [B].[Ca] GTUNMKRGRHOANR-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- MEKUERBZVYOCSL-UHFFFAOYSA-N dicalcium dioxidoboranyloxy(dioxido)borane Chemical compound [Ca+2].[Ca+2].[O-]B([O-])OB([O-])[O-] MEKUERBZVYOCSL-UHFFFAOYSA-N 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- -1 metal sulfate(s) Chemical compound 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052592 oxide mineral Inorganic materials 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001180 sulfating effect Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- VLCLHFYFMCKBRP-UHFFFAOYSA-N tricalcium;diborate Chemical class [Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-] VLCLHFYFMCKBRP-UHFFFAOYSA-N 0.000 description 1
- 229910001727 uranium mineral Inorganic materials 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Images
Classifications
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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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/06—Sulfating roasting
-
- 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
-
- 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
-
- 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
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
-
- 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 treatment of metal containing ores and concentrates and provides a method of producing metal oxides by sulfatization of a sulfide-free ore and/or concentrate comprising sulfide-free minerals, such as sulfide-free ores and/or concentrates containing metal oxides.
- Salih Ugur Bayca describes in Recovery of Boric Acid from Colemanite Waste by Sulfuric Acid Leaching and Crystallization (2nd International Symposium on Sustainable Development, Jun. 8-9, 2010, Sarajevo) production of sulfates by leaching in sulfuric acid solution.
- this well-known technology has a lot of disadvantages. For example, the handling of sulfuric acid is coupled with high production costs and potential risks related to long-distance transportation of the sulfuric acid and significant waste water problems related to the handling of sulfuric acid.
- U.S. Pat. No. 1,636,456 discloses a method for treating borate ore for the recovery of boron compounds by means of a hot ammonium chloride solution.
- this method aims at in-situ recovery of calcium boron compounds and does not allow a separation between boron compounds and contained impurities.
- Publication WO 2012/093170 discloses a method for the recovery of niobium and tantalum utilizing roasting with an acidic roasting agent providing roasting in a sulfate medium.
- the ore mentioned is suitably an oxide mineral.
- the said publication does not offer a solution for the fact that the acidic roasting agent is only partially used for the sulfating reaction thus resulting in a high consumption of the acidic roasting agent.
- An object of the present invention is to provide a method for selective recovery of desired metals from sulfide-free ore and/or concentrate.
- the objects of the invention are achieved by a method which is characterized by what is stated in the independent claim.
- the preferred embodiments of the invention are disclosed in the dependent claims.
- the invention is based on the idea of sulfatizing sulfide-free minerals in a dry process by contacting the sulfide-free mineral with sulfur trioxide and thereby forming metal sulfate(s) and metal oxide(s) from the multi metal oxide(s) comprised in the sulfide-free ore.
- a further advantage of the present invention is that sulfates produced by the method can be dissolved in water if needed for further purification of the desired metals or removal of undesired metals.
- FIG. 1 is a simplified flow diagram of the method of the present invention
- FIG. 2 shows an arrangement of a low temperature process illustrating a first example of the method of the present invention
- FIG. 3 shows an alternative arrangement of a low temperature process illustrating a second example of the method of the present invention
- FIG. 4 shows an arrangement of a medium temperature process illustrating a third example of the method of the present invention
- FIG. 5 shows an arrangement of a high temperature process illustrating a fourth example of the method of the present invention.
- the present invention relates to a method of producing metal oxide(s) by sulfatizing a sulfide-free ore and/or concentrate comprising sulfide-free mineral(s), typically a sulfide-free ore and/or concentrate containing metal oxide(s).
- the method comprises the steps of:
- sulfide-free ore and/or concentrate refers to a class of ores and/or concentrates produced thereof, whereby the ore contains mineral(s) that do not contain sulfide (S2 ⁇ ) as the major anion i.e. sulfide-free mineral(s).
- S2 ⁇ sulfide-free mineral(s)
- sulfide-free ore and/or concentrate is understood to encompass sulfide-free ores, sulfide-free concentrates, sulfide-free oxides, sulfide-free hydroxides, sulfide-free silicates and any mixtures thereof.
- the method of the present invention is thus applicable for sulfatization ores/and or concentrates comprising solid sulfide-free minerals containing one or more value elements selected from the group consisting of Cu, Co, Ni, Fe, Mn, Zn, U, Al, Ti, In, Cr, V, Ag, Cd, Zr, Hg, La, Bi, and Sb, in particular borate minerals such as colemanite, ulexite, kernite or borax. Ores and/or concentrates comprising iron oxide and utilized for example in rare earth production and uranium production are also preferred.
- FIG. 1 shows a simplified flow diagram of the method of the present invention.
- sulfide-free ore and/or concentrate (I), sulfatization agent (II) and optionally oxygen (III) are fed into a sulfatization step (a) wherein the sulfide-free ore and/or concentrate is contacted with SO 3 and the sulfide-free minerals are converted into metal sulfate(s) and metal oxide(s).
- SO 3 required for the sulfatization of the sulfide-free minerals can be generated either in separate units ahead of the sulfatization reactor or in situ.
- the sulfatization agent (II) either comprises or consists of SO 3 , or SO 3 is generated in situ in the reactor from the sulfatization agent.
- the sulfatization agent (II) may comprise or consist of SO 2 and/or sulfur.
- SO 3 reacts with the multi metal oxide(s) contained in the sulfide-free mineral(s) (I) thereby forming metal sulfate(s) and metal oxide(s) and resultantly a crude product mixture (IV) comprising unreacted SO 3 , metal sulfate(s), metal oxide(s), and any unreacted sulfate-free mineral(s) is obtained.
- An example of such reaction is the sulfatization of calcium diborate (CaB 2 O 4 ):
- SO 3 is advantageously added in hyperstoichiometric amount to the sulfatization step (a).
- a stoichiometric factor of 1.3 to 1.5 is typically sufficient.
- the sulfatization step (a) is typically performed in a fluidized bed reactor (FB), a circulating fluidized bed reactor (CFB), or in an annular fluidized bed reactor (AFB).
- FB fluidized bed reactor
- CFB circulating fluidized bed reactor
- AFB annular fluidized bed reactor
- the type of the reactor depends on the fluidization behavior of the solid feed i.e. sulfide-free mineral(s), the sulfatization reaction kinetics, and the plant production capacity.
- the FB reactor is suitable for feed materials characterized by moderate and critical fluidization behavior and/or slow reaction kinetics (long retention times of solids in the reactor) as well as for lower production capacities (up to 1000 tpd).
- the CFB reactor is preferred for processing of materials with good fluidization behavior, showing fast or moderate reaction kinetics and in case when large plant production capacities are needed.
- the CFB reactor comprises a separating unit, typically a cyclone, for recycling the solids entrained with the fluidizing gas back to the reactor.
- the AFB reactor is like CFB but with special type of windbox including a central nozzle and is utilized for processes where the temperature of gas stream entering the fluidized bed reactor is higher than 400° C. or in other circumstances eliminating tuyéres.
- the temperature of the sulfatization step (a) depends on the nature of sulfide-free mineral(s) comprised in the sulfide-free ore and/or concentrate and the sulfatization agent is selected accordingly as a result of the reaction kinetics.
- the method of the invention can thus be separated into three cases:
- the temperature is advantageously 700° C. or less, preferably from 200 to 700° C., more preferably from 300 to 630° C.
- Sulfatization at low temperature is particularly suitable for sulfide-free minerals, such as borates, rare earth oxides, Th-oxides, and U-oxides.
- the temperature is advantageously from 400 to 800° C., preferably from 500 to 700° C.
- Sulfatization at a medium temperature is particularly suitable for sulfide-free minerals such as oxides of Cu, Co, Fe, or Zn and any mixtures thereof.
- the temperature is advantageously from 700 to 1200° C., preferably from 800 to 1000° C. Sulfatization at a high temperature is particularly suitable for sulfide-free minerals comprising Ni.
- the sulfatization reaction may be performed under atmospheric or slightly pressurized conditions.
- the sulfatization reaction is performed under pressure from 1 to 3 bar, more preferably from 1.2 to 1.8 bar. Optimal selection of the reaction pressure will improve the reaction kinetics and thus the yield of the desired products.
- the method further comprises (b) separating unreacted gaseous sulfur trioxide SO 3 from the formed metal sulfate(s) and metal oxide(s). In a further example of the present invention at least part of the separated unreacted SO 3 is recycled back to the SO 3 generation step and/or the sulfatization step.
- the crude product mixture (IV) obtained from the sulfatization step (a) is be subjected to a separation step (b), wherein gas and solid fractions of the crude product mixture are separated i.e. unreacted gaseous SO 3 (V) is separated from the formed metal sulfate(s), metal oxide(s), and any remaining unreacted sulfur-free minerals (VI).
- a separation step (b) gas and solid fractions of the crude product mixture are separated i.e. unreacted gaseous SO 3 (V) is separated from the formed metal sulfate(s), metal oxide(s), and any remaining unreacted sulfur-free minerals (VI).
- SO 3 required in step (a) is produced by combining sulfur with oxygen to form SO 2 and further catalytically converting the sulfur dioxide into SO 3 .
- SO 3 is typically produced in separate units ahead of the sulfatization reactor.
- the temperature in the catalytic conversion of sulfur dioxide into sulfur trioxide is advantageously maintained in a range of 400 to 630° C. for ensuring maximum conversion of SO 2 to SO 3 .
- the temperature in the catalytic conversion can be controlled by gas/gas heat exchangers situated between catalytic conversion units.
- FIG. 2 shows an example of a process flow of a low temperature sulfatization process.
- Sulfide-free minerals (I) e.g. calcium borates
- Sulfide-free minerals (I) are fed into a sulfatization reactor (R- 2 ) wherein the sulfide-free minerals (I) are contacted with gaseous SO 3 ( 09 ) at an elevated temperature and under atmospheric or slightly pressurized conditions.
- SO 3 ( 09 ) introduced to the sulfatization reactor (R- 2 ) is obtained by combustion of sulfur (II) with oxygen (III) in a combustion reactor (R- 1 ) to obtain a SO 2 containing gas stream ( 01 ).
- the temperature of the combustion step is typically from 1000 to 1600° C., preferably from 1100 to 1250° C.
- the obtained SO 2 containing gas stream ( 01 ) is then sent to a catalytic reactor (K- 1 ) to oxidize SO 2 to SO 3 with the remaining oxygen. Oxidation
- the thus obtained SO 3 containing gas stream ( 04 ) may then be subjected to further oxidation steps in one or more further catalytic reactors (K- 2 , K- 3 ) to oxidize any remaining SO 2 to SO 3 with the remaining oxygen.
- the thus obtained SO 3 containing gas stream ( 09 ) is then introduced to the sulfatization reactor (R- 2 ) and reacted with the sulfur-free minerals (I) to obtain metal sulfate(s) and metal oxide(s), e.g. calcium sulfate and boron oxide.
- the interim gases leaving the catalyst layers of the catalytic reactors can be cooled down in one ore more gas/gas heat exchangers (HX- 1 H, HX- 2 H, HX- 3 H). Additionally or alternatively the temperature of the inlet SO 3 gas stream ( 09 ) can be adjusted before entering the reactor by cooling in a gas/gas heat reactor (HX- 4 H). Heat streams (Q- 01 -Q- 04 ) obtained from the heat exchangers can be led to a heat recovery unit for energy recovery.
- a SO 2 /SO 3 gas stream ( 23 / 24 ) can be fed to the reactor (R- 1 ) and/or the catalytic reactor (K- 1 ), respectively.
- the crude product mixture (VI) containing unreacted SO 3 and solids i.e. metal sulfate(s), metal oxide(s), and any unreacted sulfur-free mineral(s) can subjected to a gas-solid separation for separating unreacted gaseous SO 3 from the solids.
- a gas-solid separation for separating unreacted gaseous SO 3 from the solids.
- a first stage gas-solid separation is performed using a cyclone. Part of the separated solids can be recirculated and fed back to the sulfatization step (a).
- the crude product mixture ( 10 ) obtained from the reactor (R- 2 ) is thus introduced into a cyclone (CYC- 1 ) to obtain a solid stream ( 62 ) and an off-gas stream ( 11 ).
- a filter (FI- 1 ) the exiting off-gas ( 11 ) from the cyclone (CYC- 1 ) is filtered from the solid particles not captured by the cyclone.
- purified off-gas ( 13 ) may be recycled to SO 3 production and the solids ( 66 ) can be combined with the solid stream ( 62 ).
- a fluidized bed heat exchanger may be connected to the reactor (R- 2 ) to remove heat from the reactor.
- Type of the heat exchangers utilized in the method of the invention depends on the heat integration of the steam system with operating and economical aspects. Examples of suitable heat exchangers include waste heat boilers, economizers, evaporators, and reboilers.
- the separated unreacted sulfur trioxide i.e. the off-gas
- the off-gas can be recirculated into the sulfatization step (a) and/or into SO 2 and/or SO 3 generation steps.
- the off-gas stream ( 14 ) is first cooled down in one or more heat exchangers (HX- 5 H, HX- 6 , HX- 8 ), after which it is optionally fed into a liquid demister (F- 1 ) before it is recycled into the above mentioned process steps through a recycle gas compressor (C- 1 ).
- the liquid demister (F- 1 ) can be used to remove moisture from the gas stream.
- FIG. 3 shows a further example of a process flow of a low temperature sulfatization process.
- air stream (X′) is fed into the combustion reactor (R- 1 ), where SO 2 is produced to obtain a SO 2 containing gas stream ( 01 ).
- the obtained SO 2 containing gas stream ( 01 ) is then sent to a catalytic reactor (K- 1 ) to oxidize SO 2 to SO 3 with the remaining oxygen.
- the thus obtained SO 3 containing gas stream ( 04 ) is then be subjected to further oxidation steps in further catalytic reactors (K- 2 , K- 3 ) to oxidize any remaining SO 2 to SO 3 with the remaining oxygen.
- the thus obtained SO 3 containing gas stream ( 09 ) is then introduced to the sulfatization reactor (R- 2 ) and reacted with the sulfur-free minerals (I) to obtain metal sulfate(s) and metal oxide(s).
- the method may also comprise cooling of the off-gas stream between the sulfatization step (a) and the gas-solid separation step (b).
- the cooling is typically performed by a waste heat boiler or a recuperator and by this is assured that the sensible heat of the off-gas can be used either for steam production or elsewhere in the process.
- off-gas ( 11 ) obtained from the cyclone (CYC- 1 ) is cooled in a waste heat boiler (WHB) where its temperature is reduced to 200 to 500° C., preferably to approx. 300° C. before entering into the filter (FI- 1 ) for final separation of the gas and solid fractions.
- WB waste heat boiler
- the separated unreacted sulfur trioxide i.e. the off-gas
- the off-gas can be recirculated into the sulfatization step (a) and/or into SO 2 and/or SO 3 generation steps.
- the recirculated off-gas is fed to a catalytic reactor to oxidize SO 2 comprised in the off-gas stream to SO 3 with the remaining oxygen. Oxidation is typically performed at temperature from 400 to 630° C.
- the SO 2 and SO 3 containing off-gas stream ( 19 ) obtained from the filter (FI- 1 ) is sent to a catalytic reactor (K- 4 ) to oxidize SO 2 to SO 3 .
- the thus obtained SO 3 enriched off-gas stream ( 14 ) can then be cooled down in one or more heat exchangers (HX- 5 H, HX- 6 , HX- 8 ), before it is recycled into the above mentioned process steps though a recycle gas compressor (C- 1 ). Cooling of the off-gas stream before it is entered into the gas compressor reduces required compression energy.
- the recycled SO 3 containing off-gas stream is treated to absorb SO 3 from the off-gas and convert it to sulfuric acid (H 2 SO 4 ).
- SO 3 containing off-gas stream ( 18 ) is fed in to a SO 3 absorber (ABS) wherein is contacted with water (VII) to provide aqueous sulfuric acid (VIII).
- VIII aqueous sulfuric acid
- Part of the obtained sulfuric acid stream ( 59 ) can be recycled back into the absorption step to ensure maximum conversion of SO 3 to sulfuric acid.
- solid fractions obtained from the gas/solid separation stages can be send to a selective desulfatization of undesired metal sulfate(s) to metal oxide(s).
- solids and gases can be separated in similar fashion as after the sulfatization step (a).
- the crude product mixture (VI) containing solids, i.e. metal sulfate(s), metal oxide(s), and any unreacted sulfur-free mineral(s) can be fed to a reactor (R- 3 ) where it is subjected to further reactions as for example controlled decomposition reactions.
- the temperature of the desulfatization step is typically from 600 to 1200° C.
- Desulfatization is typically performed in a fluidized bed reactor (FB) or a circulating fluidized bed reactor (CFB).
- FB fluidized bed reactor
- CFB circulating fluidized bed reactor
- the obtained desulfatized crude product mixture ( 28 ) is then introduced into a cyclone (CYC- 2 ) to obtain a solid stream ( 68 / 69 ) and an off-gas stream ( 29 ).
- Part of the separated solids ( 68 ) can be recirculated and fed back to the desulfatization step. Finally in a filter (FI- 2 ) the exiting off-gas ( 29 ) from the cyclone (CYC- 2 ) is filtered from the solid particles not captured by the cyclone. Thus obtained purified off-gas ( 30 ) may be recycled to SO 3 production and the desulfatized solids ( 20 ) can be recovered.
- Desulfatization is useful in cases where the sulfatization step (a) is not selective enough and undesired metal sulfates can be oxidized back to corresponding metal oxides.
- FIG. 4 shows an example of a process flow of a medium temperature sulfatization process.
- like components are designated by the same reference numerals as used in FIG. 2 and/or FIG. 3 .
- Sulfide-free mineral(s) (I) is fed into a sulfatization reactor (R- 2 ) wherein the sulfide-free mineral(s) (I) is contacted with SO 3 produced in situ from SO 2 at an elevated temperature as discussed above and under atmospheric or slightly pressurized conditions.
- SO 2 ( 02 ) introduced to the sulfatization reactor (R- 2 ) may be obtained by combustion of sulfur (II) with oxygen (III) to obtain a gas steam containing SO 2 ( 01 ) in a combustion reactor (R- 1 ).
- the temperature of the combustion stage is typically from 1000 to 1600° C., preferably from 1100 to 1350° C.
- the obtained gas stream containing SO 2 gas stream ( 01 ) is then preferably cooled in a gas/gas heat exchanger (HX-H) to 200 to 500° C. to obtain a cooled gas stream ( 02 ), and then directly fed into the sulfatization reactor (R- 2 ) together with the remaining oxygen to generate SO 3 in situ in the reactor.
- the optional heat exchanger is utilized to maintain the temperature of the sulfatization step in desired ranges.
- FIG. 5 shows an example of a process flow of a high temperature sulfatization process.
- like components are designated by the same reference numerals as used in FIG. 2 , FIG. 3 , and/or FIG. 4 .
- Sulfide-free mineral(s) (I), sulfur (II), and oxygen (III) are fed into a sulfatization reactor (R- 2 ) wherein the sulfide-free mineral(s) (I) is contacted with SO 3 produced in situ from sulfur and O 2 at an elevated temperature as discussed above and under atmospheric or slightly pressurized conditions.
- Sulfur utilized in the generation of SO 2 and/or SO 3 is preferably liquid sulfur, which is typically provided at a temperature from 120 to 150° C., or solid sulfur, which is typically provided at room temperature.
- Oxygen utilized in the generation of SO 2 is generally ambient air in order to control the reaction temperature.
- Oxygen utilized in the generation of SO 3 can be technical pure oxygen, containing typically 98.5-99.8 vol % oxygen or ambient air.
- metal sulfate(s) and metal oxide(s) can be selectively leached from the crude reaction mixture into leach liquor. For example unwanted, in solid state remaining compounds/elements can be separated from the wanted, dissolved valuable compounds/elements. This is suitable for example for sulfur-free minerals which provide calcium sulfate as a result of the sulfatization step.
- An example of such a reaction is the following:
- the method may further comprise
- the aqueous leach liquor is typically raffinate, spent acid, or water, preferably water.
- the metal oxide(s) formed in the sulfatization step (a) are leached into the leach liquor.
- boron oxide can be produced by the method of the present invention.
- Colemanite (CaB 3 O 4 (OH) 3 ⁇ H 2 O) is subjected to a decomposition and selective sulfatization reaction in the presence of SO 3 .
- Unwanted Ca is sulfated to gypsum (CaSO 4 ) and the wanted B is oxidized and finally dissolved to obtain boron oxide.
- the method may further comprise
- the aqueous leach liquor is typically water or dilute sulfuric acid.
- the metal sulfate(s) formed in the sulfatization step (a) are leached into the aqueous leach liquor.
- valuable metals can be recovered from iron containing ore by the method of the present invention.
- Iron oxide present for example in rare earth and uranium minerals is converted to soluble iron sulfate and the valuable metals remain in solid form.
- Iron sulfate is then removed by solid-liquid separation and the solids comprising the valuable metals are subjected to further processing steps to recover the valuable metals. If the valuable metals form also soluble sulfates, iron sulfate is decomposed at elevated temperature into insoluble oxide.
Abstract
The present invention provides a method of producing metal oxide(s) by sulfatizing a sulfide-free ore and/or concentrate comprising the steps of providing a sulfide-free ore and/or concentrate comprising sulfide-free mineral(s); and contacting the sulfide-free ore and/or concentrate with gaseous SO3 for sulfatizing the sulfide-free mineral(s) thereby forming metal sulfate(s) and metal oxide(s).
Description
- The present invention relates to treatment of metal containing ores and concentrates and provides a method of producing metal oxides by sulfatization of a sulfide-free ore and/or concentrate comprising sulfide-free minerals, such as sulfide-free ores and/or concentrates containing metal oxides.
- Conventionally sulfur-free minerals are first calcinated and then leached in sulfuric acid solution to separate valuable metals from the ore.
- Salih Ugur Bayca describes in Recovery of Boric Acid from Colemanite Waste by Sulfuric Acid Leaching and Crystallization (2nd International Symposium on Sustainable Development, Jun. 8-9, 2010, Sarajevo) production of sulfates by leaching in sulfuric acid solution. However, this well-known technology has a lot of disadvantages. For example, the handling of sulfuric acid is coupled with high production costs and potential risks related to long-distance transportation of the sulfuric acid and significant waste water problems related to the handling of sulfuric acid.
- U.S. Pat. No. 1,636,456 discloses a method for treating borate ore for the recovery of boron compounds by means of a hot ammonium chloride solution. However, this method aims at in-situ recovery of calcium boron compounds and does not allow a separation between boron compounds and contained impurities.
- Publication WO 2012/093170 discloses a method for the recovery of niobium and tantalum utilizing roasting with an acidic roasting agent providing roasting in a sulfate medium. The ore mentioned is suitably an oxide mineral. However, the said publication does not offer a solution for the fact that the acidic roasting agent is only partially used for the sulfating reaction thus resulting in a high consumption of the acidic roasting agent.
- An object of the present invention is to provide a method for selective recovery of desired metals from sulfide-free ore and/or concentrate. The objects of the invention are achieved by a method which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.
- The invention is based on the idea of sulfatizing sulfide-free minerals in a dry process by contacting the sulfide-free mineral with sulfur trioxide and thereby forming metal sulfate(s) and metal oxide(s) from the multi metal oxide(s) comprised in the sulfide-free ore.
- By sulfatizing sulfide-free mineral in a dry process sulfuric acid is not produced as interim product. This reduces the production costs and potential risks related to long-distance transportation of sulfuric acid are avoided. A further advantage of the present invention is that sulfates produced by the method can be dissolved in water if needed for further purification of the desired metals or removal of undesired metals.
- In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which
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FIG. 1 is a simplified flow diagram of the method of the present invention; -
FIG. 2 shows an arrangement of a low temperature process illustrating a first example of the method of the present invention; -
FIG. 3 shows an alternative arrangement of a low temperature process illustrating a second example of the method of the present invention; -
FIG. 4 shows an arrangement of a medium temperature process illustrating a third example of the method of the present invention; -
FIG. 5 shows an arrangement of a high temperature process illustrating a fourth example of the method of the present invention. - The present invention relates to a method of producing metal oxide(s) by sulfatizing a sulfide-free ore and/or concentrate comprising sulfide-free mineral(s), typically a sulfide-free ore and/or concentrate containing metal oxide(s). The method comprises the steps of:
- (o) providing a sulfide-free ore and/or concentrate comprising sulfide-free mineral(s);
- (a) contacting the sulfide-free ore and/or concentrate with gaseous sulfur trioxide (SO3) for sulfatizing the sulfide-free mineral(s) thereby forming metal sulfate(s) and metal oxide(s).
- The term “sulfide-free ore and/or concentrate” refers to a class of ores and/or concentrates produced thereof, whereby the ore contains mineral(s) that do not contain sulfide (S2−) as the major anion i.e. sulfide-free mineral(s). Advantageously the term “sulfide-free ore and/or concentrate” is understood to encompass sulfide-free ores, sulfide-free concentrates, sulfide-free oxides, sulfide-free hydroxides, sulfide-free silicates and any mixtures thereof. The method of the present invention is thus applicable for sulfatization ores/and or concentrates comprising solid sulfide-free minerals containing one or more value elements selected from the group consisting of Cu, Co, Ni, Fe, Mn, Zn, U, Al, Ti, In, Cr, V, Ag, Cd, Zr, Hg, La, Bi, and Sb, in particular borate minerals such as colemanite, ulexite, kernite or borax. Ores and/or concentrates comprising iron oxide and utilized for example in rare earth production and uranium production are also preferred.
-
FIG. 1 shows a simplified flow diagram of the method of the present invention. With reference toFIG. 1 , sulfide-free ore and/or concentrate (I), sulfatization agent (II) and optionally oxygen (III) are fed into a sulfatization step (a) wherein the sulfide-free ore and/or concentrate is contacted with SO3 and the sulfide-free minerals are converted into metal sulfate(s) and metal oxide(s). SO3 required for the sulfatization of the sulfide-free minerals can be generated either in separate units ahead of the sulfatization reactor or in situ. - Thus the sulfatization agent (II) either comprises or consists of SO3, or SO3 is generated in situ in the reactor from the sulfatization agent. In the latter case the sulfatization agent (II) may comprise or consist of SO2 and/or sulfur. In the sulfatization step (a) SO3 reacts with the multi metal oxide(s) contained in the sulfide-free mineral(s) (I) thereby forming metal sulfate(s) and metal oxide(s) and resultantly a crude product mixture (IV) comprising unreacted SO3, metal sulfate(s), metal oxide(s), and any unreacted sulfate-free mineral(s) is obtained. An example of such reaction is the sulfatization of calcium diborate (CaB2O4):
-
CaB2O4+SO3→CaSO4+B2O3 (i) - SO3 is advantageously added in hyperstoichiometric amount to the sulfatization step (a). A stoichiometric factor of 1.3 to 1.5 is typically sufficient.
- The sulfatization step (a) is typically performed in a fluidized bed reactor (FB), a circulating fluidized bed reactor (CFB), or in an annular fluidized bed reactor (AFB). The type of the reactor depends on the fluidization behavior of the solid feed i.e. sulfide-free mineral(s), the sulfatization reaction kinetics, and the plant production capacity. The FB reactor is suitable for feed materials characterized by moderate and critical fluidization behavior and/or slow reaction kinetics (long retention times of solids in the reactor) as well as for lower production capacities (up to 1000 tpd). The CFB reactor is preferred for processing of materials with good fluidization behavior, showing fast or moderate reaction kinetics and in case when large plant production capacities are needed. The CFB reactor comprises a separating unit, typically a cyclone, for recycling the solids entrained with the fluidizing gas back to the reactor. The AFB reactor is like CFB but with special type of windbox including a central nozzle and is utilized for processes where the temperature of gas stream entering the fluidized bed reactor is higher than 400° C. or in other circumstances eliminating tuyéres.
- The temperature of the sulfatization step (a) depends on the nature of sulfide-free mineral(s) comprised in the sulfide-free ore and/or concentrate and the sulfatization agent is selected accordingly as a result of the reaction kinetics. The method of the invention can thus be separated into three cases:
- For sulfatization with sulfur trioxide (SO3) as the sulfatization agent (low temperature process) the temperature is advantageously 700° C. or less, preferably from 200 to 700° C., more preferably from 300 to 630° C. Sulfatization at low temperature is particularly suitable for sulfide-free minerals, such as borates, rare earth oxides, Th-oxides, and U-oxides.
- For sulfatization with sulfur dioxide (SO2) as the sulfatization agent (medium temperature process) the temperature is advantageously from 400 to 800° C., preferably from 500 to 700° C. Sulfatization at a medium temperature is particularly suitable for sulfide-free minerals such as oxides of Cu, Co, Fe, or Zn and any mixtures thereof.
- For sulfatization with sulfur as the sulfatization agent (high temperature process) the temperature is advantageously from 700 to 1200° C., preferably from 800 to 1000° C. Sulfatization at a high temperature is particularly suitable for sulfide-free minerals comprising Ni.
- The sulfatization reaction may be performed under atmospheric or slightly pressurized conditions. Preferably the sulfatization reaction is performed under pressure from 1 to 3 bar, more preferably from 1.2 to 1.8 bar. Optimal selection of the reaction pressure will improve the reaction kinetics and thus the yield of the desired products.
- In an example of the present invention, the method further comprises (b) separating unreacted gaseous sulfur trioxide SO3 from the formed metal sulfate(s) and metal oxide(s). In a further example of the present invention at least part of the separated unreacted SO3 is recycled back to the SO3 generation step and/or the sulfatization step.
- With further reference to
FIG. 1 the crude product mixture (IV) obtained from the sulfatization step (a) is be subjected to a separation step (b), wherein gas and solid fractions of the crude product mixture are separated i.e. unreacted gaseous SO3 (V) is separated from the formed metal sulfate(s), metal oxide(s), and any remaining unreacted sulfur-free minerals (VI). - According to a further example of the present invention SO3 required in step (a) is produced by combining sulfur with oxygen to form SO2 and further catalytically converting the sulfur dioxide into SO3. In such case SO3 is typically produced in separate units ahead of the sulfatization reactor. The temperature in the catalytic conversion of sulfur dioxide into sulfur trioxide is advantageously maintained in a range of 400 to 630° C. for ensuring maximum conversion of SO2 to SO3. According to a further example of the present invention the temperature in the catalytic conversion can be controlled by gas/gas heat exchangers situated between catalytic conversion units.
-
FIG. 2 shows an example of a process flow of a low temperature sulfatization process. Sulfide-free minerals (I), e.g. calcium borates, are fed into a sulfatization reactor (R-2) wherein the sulfide-free minerals (I) are contacted with gaseous SO3 (09) at an elevated temperature and under atmospheric or slightly pressurized conditions. SO3 (09) introduced to the sulfatization reactor (R-2) is obtained by combustion of sulfur (II) with oxygen (III) in a combustion reactor (R-1) to obtain a SO2 containing gas stream (01). The temperature of the combustion step is typically from 1000 to 1600° C., preferably from 1100 to 1250° C. The obtained SO2 containing gas stream (01) is then sent to a catalytic reactor (K-1) to oxidize SO2 to SO3 with the remaining oxygen. Oxidation is typically performed at temperature from 420 to 630° C. - If required, the thus obtained SO3 containing gas stream (04) may then be subjected to further oxidation steps in one or more further catalytic reactors (K-2, K-3) to oxidize any remaining SO2 to SO3 with the remaining oxygen. The thus obtained SO3 containing gas stream (09) is then introduced to the sulfatization reactor (R-2) and reacted with the sulfur-free minerals (I) to obtain metal sulfate(s) and metal oxide(s), e.g. calcium sulfate and boron oxide. To maintain the temperature of the sulfatization step in desired ranges the interim gases leaving the catalyst layers of the catalytic reactors (K-1, K-2, K-3) can be cooled down in one ore more gas/gas heat exchangers (HX-1 H, HX-2H, HX-3H). Additionally or alternatively the temperature of the inlet SO3 gas stream (09) can be adjusted before entering the reactor by cooling in a gas/gas heat reactor (HX-4H). Heat streams (Q-01-Q-04) obtained from the heat exchangers can be led to a heat recovery unit for energy recovery. To further control the temperatures of the combustion step and/or the first catalytic conversion step a SO2/SO3 gas stream (23/24) can be fed to the reactor (R-1) and/or the catalytic reactor (K-1), respectively.
- After the sulfatization step (a) the crude product mixture (VI) containing unreacted SO3 and solids, i.e. metal sulfate(s), metal oxide(s), and any unreacted sulfur-free mineral(s) can subjected to a gas-solid separation for separating unreacted gaseous SO3 from the solids. Typically a first stage gas-solid separation is performed using a cyclone. Part of the separated solids can be recirculated and fed back to the sulfatization step (a). By using a cyclone the reaction time between the sulfide-free mineral(s) and SO3 may be extended and thereby a higher yield achieved. With further reference to
FIG. 2 , the crude product mixture (10) obtained from the reactor (R-2) is thus introduced into a cyclone (CYC-1) to obtain a solid stream (62) and an off-gas stream (11). Finally in a filter (FI-1) the exiting off-gas (11) from the cyclone (CYC-1) is filtered from the solid particles not captured by the cyclone. Thus obtained purified off-gas (13) may be recycled to SO3 production and the solids (66) can be combined with the solid stream (62). - With further reference to
FIG. 2 , a fluidized bed heat exchanger (FBC) may be connected to the reactor (R-2) to remove heat from the reactor. Type of the heat exchangers utilized in the method of the invention depends on the heat integration of the steam system with operating and economical aspects. Examples of suitable heat exchangers include waste heat boilers, economizers, evaporators, and reboilers. - The separated unreacted sulfur trioxide, i.e. the off-gas, may be used for heat production or as a source for production of weak acid possibly needed in downstream process steps such as calcine leaching. Alternatively or additionally the off-gas can be recirculated into the sulfatization step (a) and/or into SO2 and/or SO3 generation steps. With reference to
FIG. 2 , the off-gas stream (14) is first cooled down in one or more heat exchangers (HX-5H, HX-6, HX-8), after which it is optionally fed into a liquid demister (F-1) before it is recycled into the above mentioned process steps through a recycle gas compressor (C-1). The liquid demister (F-1) can be used to remove moisture from the gas stream. - In accordance with a suitable example of the present invention air is utilized to control the oxygen concentration in the SO2 generation step. This ensures optimum temperature control of the oxidation.
FIG. 3 shows a further example of a process flow of a low temperature sulfatization process. InFIG. 3 , like components are designated by the same reference numerals as used inFIG. 2 . With reference toFIG. 3 , air stream (X′) is fed into the combustion reactor (R-1), where SO2 is produced to obtain a SO2 containing gas stream (01). The obtained SO2 containing gas stream (01) is then sent to a catalytic reactor (K-1) to oxidize SO2 to SO3 with the remaining oxygen. The thus obtained SO3 containing gas stream (04) is then be subjected to further oxidation steps in further catalytic reactors (K-2, K-3) to oxidize any remaining SO2 to SO3 with the remaining oxygen. The thus obtained SO3 containing gas stream (09) is then introduced to the sulfatization reactor (R-2) and reacted with the sulfur-free minerals (I) to obtain metal sulfate(s) and metal oxide(s). - According to a further example of the present invention the method may also comprise cooling of the off-gas stream between the sulfatization step (a) and the gas-solid separation step (b). The cooling is typically performed by a waste heat boiler or a recuperator and by this is assured that the sensible heat of the off-gas can be used either for steam production or elsewhere in the process.
- With reference to
FIG. 3 , off-gas (11) obtained from the cyclone (CYC-1) is cooled in a waste heat boiler (WHB) where its temperature is reduced to 200 to 500° C., preferably to approx. 300° C. before entering into the filter (FI-1) for final separation of the gas and solid fractions. - The separated unreacted sulfur trioxide, i.e. the off-gas, may be used for heat production or as a source for production of weak acid possibly needed in downstream process steps such as calcine leaching. Alternatively or additionally the off-gas can be recirculated into the sulfatization step (a) and/or into SO2 and/or SO3 generation steps. Optionally the recirculated off-gas is fed to a catalytic reactor to oxidize SO2 comprised in the off-gas stream to SO3 with the remaining oxygen. Oxidation is typically performed at temperature from 400 to 630° C.
- With reference to
FIG. 3 the SO2 and SO3 containing off-gas stream (19) obtained from the filter (FI-1) is sent to a catalytic reactor (K-4) to oxidize SO2 to SO3. The thus obtained SO3 enriched off-gas stream (14) can then be cooled down in one or more heat exchangers (HX-5H, HX-6, HX-8), before it is recycled into the above mentioned process steps though a recycle gas compressor (C-1). Cooling of the off-gas stream before it is entered into the gas compressor reduces required compression energy. - Optionally the recycled SO3 containing off-gas stream is treated to absorb SO3 from the off-gas and convert it to sulfuric acid (H2SO4). With reference to
FIG. 3 , SO3 containing off-gas stream (18) is fed in to a SO3 absorber (ABS) wherein is contacted with water (VII) to provide aqueous sulfuric acid (VIII). Part of the obtained sulfuric acid stream (59) can be recycled back into the absorption step to ensure maximum conversion of SO3 to sulfuric acid. - In accordance with a further example of the present invention solid fractions obtained from the gas/solid separation stages can be send to a selective desulfatization of undesired metal sulfate(s) to metal oxide(s). After the desulfatization step solids and gases can be separated in similar fashion as after the sulfatization step (a).
- With further reference to
FIG. 3 , the crude product mixture (VI) containing solids, i.e. metal sulfate(s), metal oxide(s), and any unreacted sulfur-free mineral(s) can be fed to a reactor (R-3) where it is subjected to further reactions as for example controlled decomposition reactions. The temperature of the desulfatization step is typically from 600 to 1200° C. Desulfatization is typically performed in a fluidized bed reactor (FB) or a circulating fluidized bed reactor (CFB). The obtained desulfatized crude product mixture (28) is then introduced into a cyclone (CYC-2) to obtain a solid stream (68/69) and an off-gas stream (29). Part of the separated solids (68) can be recirculated and fed back to the desulfatization step. Finally in a filter (FI-2) the exiting off-gas (29) from the cyclone (CYC-2) is filtered from the solid particles not captured by the cyclone. Thus obtained purified off-gas (30) may be recycled to SO3 production and the desulfatized solids (20) can be recovered. - Desulfatization is useful in cases where the sulfatization step (a) is not selective enough and undesired metal sulfates can be oxidized back to corresponding metal oxides.
-
FIG. 4 shows an example of a process flow of a medium temperature sulfatization process. InFIG. 4 , like components are designated by the same reference numerals as used inFIG. 2 and/orFIG. 3 . - Sulfide-free mineral(s) (I) is fed into a sulfatization reactor (R-2) wherein the sulfide-free mineral(s) (I) is contacted with SO3 produced in situ from SO2 at an elevated temperature as discussed above and under atmospheric or slightly pressurized conditions. SO2 (02) introduced to the sulfatization reactor (R-2) may be obtained by combustion of sulfur (II) with oxygen (III) to obtain a gas steam containing SO2 (01) in a combustion reactor (R-1). The temperature of the combustion stage is typically from 1000 to 1600° C., preferably from 1100 to 1350° C. The obtained gas stream containing SO2 gas stream (01) is then preferably cooled in a gas/gas heat exchanger (HX-H) to 200 to 500° C. to obtain a cooled gas stream (02), and then directly fed into the sulfatization reactor (R-2) together with the remaining oxygen to generate SO3 in situ in the reactor. The optional heat exchanger is utilized to maintain the temperature of the sulfatization step in desired ranges.
-
FIG. 5 shows an example of a process flow of a high temperature sulfatization process. InFIG. 5 , like components are designated by the same reference numerals as used inFIG. 2 ,FIG. 3 , and/orFIG. 4 . Sulfide-free mineral(s) (I), sulfur (II), and oxygen (III) are fed into a sulfatization reactor (R-2) wherein the sulfide-free mineral(s) (I) is contacted with SO3 produced in situ from sulfur and O2 at an elevated temperature as discussed above and under atmospheric or slightly pressurized conditions. - Sulfur utilized in the generation of SO2 and/or SO3 is preferably liquid sulfur, which is typically provided at a temperature from 120 to 150° C., or solid sulfur, which is typically provided at room temperature. Oxygen utilized in the generation of SO2 is generally ambient air in order to control the reaction temperature. Oxygen utilized in the generation of SO3 can be technical pure oxygen, containing typically 98.5-99.8 vol % oxygen or ambient air.
- Depending on the nature of the obtained metal sulfate(s) and metal oxide(s), one of them can be selectively leached from the crude reaction mixture into leach liquor. For example unwanted, in solid state remaining compounds/elements can be separated from the wanted, dissolved valuable compounds/elements. This is suitable for example for sulfur-free minerals which provide calcium sulfate as a result of the sulfatization step. An example of such a reaction is the following:
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CaSO4+B2O3+4H2O→2H3BO3(aq)+CaSO4·H2O(s) (ii) - Thus according to a preferred example of the invention the method may further comprise
- (c) leaching the formed metal sulfate(s) and metal oxide(s) in an aqueous leach liquor thereby extracting the metal oxide(s) into the aqueous leach liquor; and
- (d) performing a solid-liquid separation for separating the metal sulfate(s) remaining in solid state from the dissolved metal oxide(s).
- The aqueous leach liquor is typically raffinate, spent acid, or water, preferably water. Thus the metal oxide(s) formed in the sulfatization step (a) are leached into the leach liquor.
- As an example of the above, boron oxide can be produced by the method of the present invention. Colemanite (CaB3O4(OH)3·H2O) is subjected to a decomposition and selective sulfatization reaction in the presence of SO3. Unwanted Ca is sulfated to gypsum (CaSO4) and the wanted B is oxidized and finally dissolved to obtain boron oxide.
- According to an alternative preferred example of the invention the method may further comprise
- (c) leaching the formed metal sulfate(s) and metal oxide(s) in an aqueous leach liquor thereby extracting the metal sulfate(s) into the aqueous leach liquor; and
- (d) performing a solid-liquid separation for separating the metal oxide(s) remaining in solid state from the dissolved metal sulfate(s).
- In this case the aqueous leach liquor is typically water or dilute sulfuric acid. Thus the metal sulfate(s) formed in the sulfatization step (a) are leached into the aqueous leach liquor.
- As an example of the above, valuable metals can be recovered from iron containing ore by the method of the present invention. Iron oxide present for example in rare earth and uranium minerals is converted to soluble iron sulfate and the valuable metals remain in solid form. Iron sulfate is then removed by solid-liquid separation and the solids comprising the valuable metals are subjected to further processing steps to recover the valuable metals. If the valuable metals form also soluble sulfates, iron sulfate is decomposed at elevated temperature into insoluble oxide.
- It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.
Claims (18)
1. A method of producing metal oxide(s) by sulfatizing a sulfide-free ore and/or concentrate comprising:
(o) providing a sulfide-free ore and/or concentrate comprising sulfide-free mineral(s); and
(a) contacting the sulfide-free ore and/or concentrate with gaseous SO3 for sulfatizing the sulfide-free mineral(s) thereby forming metal sulfate(s) and metal oxide(s).
2. The method as claimed in claim 1 , wherein the sulfide-free ore and/or concentrate is selected from the group consisting of sulfide-free ores, sulfide-free concentrates, sulfide-free oxides, sulfide-free hydroxides, sulfide-free silicates, and any mixtures thereof, preferably from sulfide-free ores and/or concentrates comprising borate minerals and/or iron oxides.
3. The method as claimed in claim 1 , wherein the sulfide-free mineral is contacted with SO3 in a fluidized bed reactor (FB), circulating fluidized bed reactor (CFB) or annular fluidized bed reactor (AFB).
4. The method as claimed in claim 1 , wherein the SO3 used in step (a) is produced in situ from sulfur.
5. The method as claimed in claim 1 , wherein the SO3 used in step (a) is produced in situ from sulfur dioxide (SO2).
6. The method as claimed in claim 1 , wherein the SO3 used in step (a) is produced by combining sulfur with oxygen to form sulfur dioxide and further catalytically converting the sulfur dioxide into sulfur trioxide.
7. The method as claimed in claim 6 , wherein sulfur trioxide (SO3) is produced in separate units ahead of the sulfatization reactor.
8. The method as claimed in claim 4 , wherein the temperature of step (a) is from 700 to 1200° C., preferably from 800 to 1000° C.
9. The method as claimed in claim 5 , wherein the temperature of step (a) is from 400 to 800° C., preferably from 500 to 700° C.
10. The method as claimed in claim 6 , wherein the temperature of step (a) is from 200 to 700° C., more preferably from 300 to 630° C.
11. The method as claimed in claim 1 , wherein step (a) is performed under pressure from atmospheric pressure 1 to 3 bar, preferably from 1.2 to 1.8 bar.
12. The method as claimed in claim 1 , wherein the method further comprises:
(b) separating unreacted gaseous SO3 from the formed metal sulfate(s) and metal oxide(s).
13. A method as claimed in claim 1 , wherein the method further comprises:
(c) leaching the formed metal sulfate(s) and metal oxide(s) in an aqueous leach liquor thereby extracting the metal oxide(s) into the aqueous leach liquor; and
(d) performing a solid-liquid separation for separating the metal sulfate(s) remaining in solid state from the dissolved metal oxide(s).
14. A method as claimed in claim 1 , wherein the method further comprises:
(c) leaching the formed metal sulfate(s) and metal oxide(s) in an aqueous leach liquor thereby extracting the metal sulfate(s) into the aqueous leach liquor; and
(d) performing a solid-liquid separation for separating the metal oxide(s) remaining in solid state from the dissolved metal sulfate(s).
15. The method claimed in claim 14 , wherein the aqueous leach liquor is raffinate, spent acid, or water, preferably water.
16. The method as claimed in claim 1 , wherein the sulfide-free ore and/or concentrate is selected from the group consisting of ores and/or concentrates comprising solid sulfide-free minerals containing one or more value elements selected from the group consisting of Cu, Co, Ni, Fe, Mn, Zn, U, Al, Ti, In, Cr, V, Ag, Cd, Zr, Hg, La, Bi, and Sb, in particular borate minerals such as colemanite, ulexite, kernite or borax.
17. The method as claimed in claim 7 , wherein the temperature of step (a) is from 200 to 700° C., more preferably from 300 to 630° C.
18. The method claimed in claim 13 , wherein the aqueous leach liquor is raffinate, spent acid, or water, preferably water.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/EP2013/076214 WO2015086060A1 (en) | 2013-12-11 | 2013-12-11 | Method for treating sulfide-free minerals |
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US20160355905A1 true US20160355905A1 (en) | 2016-12-08 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US15/101,431 Abandoned US20160355905A1 (en) | 2013-12-11 | 2013-12-11 | Method for treating sulfide-free minerals |
Country Status (6)
Country | Link |
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US (1) | US20160355905A1 (en) |
EP (1) | EP3080315B1 (en) |
AU (2) | AU2013407374A1 (en) |
CA (1) | CA2932370C (en) |
WO (1) | WO2015086060A1 (en) |
ZA (1) | ZA201604162B (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1007873A (en) * | 1962-04-30 | 1965-10-22 | Enrico Asseo | Process for the manufacture of boric acid from calcium borate ores |
US3454359A (en) * | 1966-04-29 | 1969-07-08 | Stauffer Chemical Co | Process for producing boric acid from alkali metal borates |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2036015A (en) * | 1933-04-19 | 1936-03-31 | Bethlehem Mines Corp | Preferential sulphatization of complex ores |
US3148022A (en) * | 1961-10-17 | 1964-09-08 | Du Pont | Process for extracting beryllium values from ores |
US3650679A (en) * | 1970-01-12 | 1972-03-21 | Anaconda Co | Refining low-grade beryllium ores by treatment with anhydrous sulfur trioxide |
SE396968B (en) * | 1975-07-01 | 1977-10-10 | Boliden Ab | PROCEDURE FOR EXTRACTING NON-IRON METALS FROM SULPHIDY MATERIALS BY ROASTING AND LACHING |
LU81602A1 (en) * | 1979-08-13 | 1981-03-24 | Metallurgie Hoboken | PROCESS FOR RECOVERY OF NON-FERROUS METALS CONTAINED IN A RESIDUE RICH IN IRON OXIDE AND / OR HYDROXIDE |
-
2013
- 2013-12-11 US US15/101,431 patent/US20160355905A1/en not_active Abandoned
- 2013-12-11 WO PCT/EP2013/076214 patent/WO2015086060A1/en active Application Filing
- 2013-12-11 AU AU2013407374A patent/AU2013407374A1/en not_active Abandoned
- 2013-12-11 CA CA2932370A patent/CA2932370C/en not_active Expired - Fee Related
- 2013-12-11 EP EP13802980.6A patent/EP3080315B1/en active Active
-
2016
- 2016-06-21 ZA ZA2016/04162A patent/ZA201604162B/en unknown
-
2018
- 2018-09-03 AU AU2018226384A patent/AU2018226384B2/en not_active Ceased
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1007873A (en) * | 1962-04-30 | 1965-10-22 | Enrico Asseo | Process for the manufacture of boric acid from calcium borate ores |
US3454359A (en) * | 1966-04-29 | 1969-07-08 | Stauffer Chemical Co | Process for producing boric acid from alkali metal borates |
Also Published As
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AU2013407374A1 (en) | 2016-07-14 |
AU2018226384B2 (en) | 2020-01-16 |
CA2932370A1 (en) | 2015-06-18 |
WO2015086060A1 (en) | 2015-06-18 |
EP3080315B1 (en) | 2019-07-03 |
EP3080315A1 (en) | 2016-10-19 |
CA2932370C (en) | 2021-01-26 |
AU2018226384A1 (en) | 2018-09-27 |
ZA201604162B (en) | 2017-08-30 |
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