CN117364177A - Method for preparing metallic iron and ferrosilicon alloy by electrolysis of molten oxide fluoride system - Google Patents
Method for preparing metallic iron and ferrosilicon alloy by electrolysis of molten oxide fluoride system Download PDFInfo
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- CN117364177A CN117364177A CN202311511500.7A CN202311511500A CN117364177A CN 117364177 A CN117364177 A CN 117364177A CN 202311511500 A CN202311511500 A CN 202311511500A CN 117364177 A CN117364177 A CN 117364177A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 165
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 69
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 33
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 27
- 239000000956 alloy Substances 0.000 title claims abstract description 27
- 229910000519 Ferrosilicon Inorganic materials 0.000 title claims abstract description 26
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 title claims abstract description 9
- 239000003792 electrolyte Substances 0.000 claims abstract description 39
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 17
- 229910004261 CaF 2 Inorganic materials 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 9
- 238000000227 grinding Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 230000001681 protective effect Effects 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 229910001338 liquidmetal Inorganic materials 0.000 claims abstract description 6
- 239000012298 atmosphere Substances 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims description 14
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 229910002804 graphite Inorganic materials 0.000 claims description 6
- 239000010439 graphite Substances 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 5
- 229910052741 iridium Inorganic materials 0.000 claims description 4
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 4
- PXXKQOPKNFECSZ-UHFFFAOYSA-N platinum rhodium Chemical compound [Rh].[Pt] PXXKQOPKNFECSZ-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 abstract description 11
- 239000002184 metal Substances 0.000 abstract description 11
- 239000002994 raw material Substances 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 238000002844 melting Methods 0.000 abstract description 4
- 230000008018 melting Effects 0.000 abstract description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 abstract description 3
- 239000011707 mineral Substances 0.000 abstract description 3
- 239000010405 anode material Substances 0.000 abstract description 2
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 150000003839 salts Chemical class 0.000 description 12
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 11
- 229910052721 tungsten Inorganic materials 0.000 description 9
- 239000010937 tungsten Substances 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 238000004506 ultrasonic cleaning Methods 0.000 description 8
- 229910052582 BN Inorganic materials 0.000 description 6
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 6
- 239000012300 argon atmosphere Substances 0.000 description 6
- 239000000155 melt Substances 0.000 description 6
- 244000137852 Petrea volubilis Species 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 208000005156 Dehydration Diseases 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 230000018044 dehydration Effects 0.000 description 4
- 238000006297 dehydration reaction Methods 0.000 description 4
- 238000000724 energy-dispersive X-ray spectrum Methods 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 239000010431 corundum Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910001507 metal halide Inorganic materials 0.000 description 1
- 150000005309 metal halides Chemical class 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000012256 powdered iron Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/36—Alloys obtained by cathodic reduction of all their ions
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
The invention belongs to the technical field of metal iron metallurgy, and provides a method for preparing metal iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system, which comprises the following steps: siO is carried out under the atmosphere of protective gas 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 Grinding and drying are sequentially carried out after mixing, so as to obtain a molten oxide electrolyte; and (3) electrolyzing the molten oxide electrolyte by taking a tungsten wire as a cathode and an inert material as an anode to obtain liquid metal iron and ferrosilicon alloy. The method for preparing the metal iron and the ferrosilicon alloy by electrolyzing and melting the oxide electrolyte is simple, strong in operability, green and efficient; the residual mineral components of tailings after iron separation of the bayan obo ores are used as raw materials, and metal iron and ferrosilicon alloy are efficiently prepared from the ores in one step, so that the energy consumption for preparing the whole metal iron is reduced; using a suitable inert anode material, CO is reduced 2 Even up to CO 2 Is not discharged.
Description
Technical Field
The invention relates to the technical field of metal iron metallurgy, in particular to a method for preparing metal iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system.
Background
Pure iron has good soft magnetism, corrosion resistance, electric conduction, heat conduction and other performances, and is widely applied to the fields of aerospace, automobiles, military industry manufacture, electromagnetic elements and the like. Metallic iron and its alloys will still be the most widely used structural material in industrial production and life for a long time now and in the future. In the conventional method, metallic iron is smelted by carbothermic reduction of iron ore in a blast furnace or an electric arc furnace. Coke is an indispensable raw material in this process. However, as fossil energy sources continue to be developed and utilized, their corresponding reserves continue to decrease, which will certainly place a limit on the carbothermic reduction of iron ore. In addition, coke is used as a reducing agent, a large amount of carbon dioxide gas is generated in the production process of steel, and the global climate is directly warmed due to the large-scale emission of the carbon dioxide gas, so that the environment is greatly influenced.
By means of electrochemical metallurgical technology with electron transfer as an energy carrier, the reaction process is easy to regulate and control, is expected to have higher energy efficiency, and has achieved great success in the field of aluminum electrolysis. Currently, many researchers have also successfully produced metallic iron or iron alloys by electrochemical methods. In general, electrochemical iron making is represented by molten salt electro-deoxidation, that is, cambridge, molten salt electrolysis, and molten oxide electrolysis. The Cambridge method is an electrochemical metallurgical process proposed by the university of Cambridge Fray et al. In this method, generally, a graphite electrode is used as an anode, a solid iron oxide is used as a cathode, and metallic iron is obtained at the cathode by direct electrolytic reduction at a temperature lower than the melting point of the metal and a voltage of molten salt decomposition. However, the electro-deoxidation of molten salt to produce iron still requires a purer iron oxide raw material, and the electro-deoxidation to produce iron products which are agglomerates composed of tiny iron particles, and it is difficult to effectively separate the solidified molten salt and reduce the oxygen content of the products.
Molten salt electrolysis for producing iron generally uses a molten salt such as a metal halide or carbonate as an electrolyte. Iron oxide is an iron-containing raw material, and is dissolved in molten salt, iron is precipitated on the cathode, and oxygen is precipitated on the inert anode. Compared with the method for preparing iron by molten oxide electrolysis, the method for preparing iron by molten salt electrolysis has low electrolysis temperature. However, iron oxide has low solubility in molten salt, resulting in low limiting current density in the electrolysis process, low production efficiency of iron, and low electrolysis efficiency. In addition, the product of molten salt electrolysis is usually powdered iron, which is difficult to separate from molten electrolyte, and continuous production is difficult to achieve. The preparation method of the common metallic iron has the problems of complex process, low electrolysis efficiency, high energy consumption, difficult continuous production, environmental pollution and the like.
Molten oxide electrolysis is a promising sustainable iron extraction method, and is used for directly electrolyzing and decomposing iron ore to obtain liquid metal iron and pure oxygen. During electrolysis, an electric current is applied between the two electrodes to provide the necessary electromotive force to decompose the ore into metallic iron and oxygen. Iron ore (typically hematite (Fe) 2 O 3 ) Directly into the cell and the operating temperature is set above the ferrous melting point (1811K) without concern for volatilization.
Therefore, the research on the method for preparing the metallic iron and the alloy thereof by electrolyzing the molten oxide fluoride, which reduces the energy consumption, is green and efficient, and has important significance.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for preparing metallic iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for preparing metallic iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system, which comprises the following steps:
1) SiO is carried out under the atmosphere of protective gas 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 Grinding and drying are sequentially carried out after mixing, so as to obtain a molten oxide electrolyte;
2) And (3) electrolyzing the molten oxide electrolyte by taking a tungsten wire as a cathode and an inert material as an anode to obtain liquid metal iron and ferrosilicon alloy.
As a best effortOptionally, step 1) the SiO 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The mass ratio of (2) is 40-50: 20-30: 10-30: 5 to 20.
Preferably, the SiO of step 1) 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The residual components of tailings after iron separation of the bayan obo ores; the flow rate of the protective gas is 0.3-0.5 m 3 /h。
Preferably, the drying temperature in the step 1) is 160-240 ℃, the drying time is 30-50 h, and the heating rate from the heating to the drying temperature is 2-6 ℃/min.
Preferably, the temperature of the electrolysis in the step 2) is 1200-1600 ℃, and the temperature rising rate from the temperature rising to the electrolysis temperature is 4-6 ℃/min.
Preferably, the electrolysis is carried out by charging current after the heat preservation at the electrolysis temperature, wherein the heat preservation time is 30-150 min, and the electrolysis time is 1-15 h.
Preferably, in the electrolysis in step 2), the current density is 0.1 to 2.5A/cm 2 The area ratio of the anode to the cathode is 5-10: 1.
preferably, the inert material of step 2) is graphite, platinum rhodium or iridium.
Preferably, in the step 2), when the reduction potential of the electrolysis is 0.3-0.6V, liquid metal iron is obtained; when the reduction potential of electrolysis is 0-0.3V, the ferrosilicon alloy is obtained.
The beneficial effects of the invention include:
1) The method for preparing the metal iron and the ferrosilicon alloy by electrolyzing and melting the oxide electrolyte is simple, strong in operability, green and efficient.
2) The residual mineral components of tailings after the iron is selected from the bayan obo ore are used as raw materials, and the metal iron and the ferrosilicon alloy can be efficiently prepared from the ores in one step, so that the energy consumption for preparing the whole metal iron is reduced, and good economic benefits are obtained.
3) Compared with the traditional method for smelting metallic iron by using a blast furnace electric furnace, the invention uses the proper inert anode material, reduces CO 2 Even up to CO 2 Is not discharged.
Drawings
FIG. 1 is a schematic view of a high temperature furnace for electrolyzing a molten oxide electrolyte according to the present invention, wherein 1 is a boron nitride crucible, 2 is a tube furnace, 3 is a refractory brick, 4 is a water-cooled flange, 5 is a corundum tube, 6 is a working electrode, 7 is a reference electrode, 8 is a counter electrode, 9 is an air outlet, and 10 is an air inlet;
FIG. 2 is a diagram of the product obtained in example 1;
FIG. 3 is an XRD pattern of the product prepared in example 1;
FIG. 4 is a diagram of the product obtained in example 2;
FIG. 5 is an XRD pattern of the product prepared in example 2;
FIG. 6 is an EDX spectrum of the ferrosilicon alloy prepared in example 3;
fig. 7 is an EDX spectrum of the ferrosilicon alloy prepared in example 4.
Detailed Description
The invention provides a method for preparing metallic iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system, which comprises the following steps:
1) SiO is carried out under the atmosphere of protective gas 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 Grinding and drying are sequentially carried out after mixing, so as to obtain a molten oxide electrolyte;
2) And (3) electrolyzing the molten oxide electrolyte by taking a tungsten wire as a cathode and an inert material as an anode to obtain liquid metal iron and ferrosilicon alloy.
In the present invention, step 1) is the SiO 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The mass ratio of (2) is preferably 40-50: 20-30: 10-30: 5 to 20, more preferably 42 to 48:23 to 28: 15-25: 8 to 15, more preferably 45:25:20:10 to 13.
In the present invention, step 1) is the SiO 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The residual components of tailings after iron separation of the bayan obo ore are preferable; the flow rate of the shielding gas is preferably 0.3-0.5 m 3 /h, further preferredIs 0.35 to 0.45m 3 /h, more preferably 0.4m 3 /h; the shielding gas is preferably nitrogen or argon.
After the iron and rare earth elements are extracted from the bayan obo mineral resources, the remaining tailings are piled up as waste in a waste bin. However, the tailings still contain a large amount of valuable elements such as niobium, titanium, iron and the like, which cannot be fully utilized, become potential secondary resources, and cannot be extracted by adopting the traditional smelting method. The valuable elements of the tailings after the iron separation of the bayan obo ores are subjected to molten salt electrolysis, so that iron and ferrosilicon in the tailings can be fully extracted, and the tailings are high in calcium fluoride content and can be used as a cosolvent, so that the electrolyte performance is improved, the electrolyte viscosity is reduced, and the ion conductivity is improved.
In the present invention, the drying temperature in step 1) is preferably 160 to 240 ℃, more preferably 170 to 220 ℃, and even more preferably 180 to 200 ℃; the drying time is preferably 30 to 50 hours, more preferably 35 to 45 hours, and still more preferably 40 hours; the heating rate to the drying temperature is preferably 2 to 6℃per minute, more preferably 3 to 5℃per minute, and even more preferably 4℃per minute.
In the present invention, the temperature of the electrolysis in step 2) is preferably 1200 to 1600 ℃, more preferably 1350 to 1500 ℃, and even more preferably 1400 to 1450 ℃; the rate of heating to the electrolysis temperature is preferably 4 to 6℃per minute, more preferably 4.5 to 5.5℃per minute, and even more preferably 5℃per minute.
In the invention, the electrolysis is preferably performed by supplying current after the heat preservation at the electrolysis temperature, wherein the heat preservation time is preferably 30-150 min, more preferably 50-140 min, and even more preferably 70-120 min; the electrolysis time is preferably 1 to 15 hours, more preferably 5 to 12 hours, and still more preferably 6 to 8 hours.
In the present invention, the density of the current in the electrolysis in step 2) is preferably 0.1 to 2.5A/cm 2 More preferably 0.5 to 2A/cm 2 More preferably 0.8 to 1.5A/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The area ratio of the anode to the cathode is preferably 5 to 10:1, more preferably 6 to 9:1, more preferably 7 to 8:1.
in the present invention, electrolysis is preferably performed under a protective atmosphere.
In the present invention, the inert material of step 2) is preferably graphite, platinum rhodium or iridium.
In the present invention, when the reduction potential of the electrolysis in step 2) is 0.3 to 0.6V (excluding 0.3V), liquid metallic iron is obtained, preferably 0.4 to 0.5V; when the reduction potential of electrolysis is 0 to 0.3V, a ferrosilicon alloy is obtained, preferably 0.1 to 0.2V.
In the present invention, the diameter of the tungsten filament is preferably 1 to 3mm, more preferably 1.5 to 2.5mm, and still more preferably 2mm; the purity of the tungsten filament is preferably 98 to 99.99%, more preferably 98.5 to 99.95%, and still more preferably 99 to 99.9%.
In the invention, the tungsten filament in the step 2) is preferably a tungsten filament which is sequentially subjected to polishing, acid soaking and cleaning, and the polishing is preferably polishing by adopting 200-mesh, 400-mesh, 600-mesh, 800-mesh, 1000-mesh and 1200-mesh sand paper in sequence; the acid soaking time is preferably 2 to 3 hours, more preferably 2.5 hours; the cleaning is preferably ultrasonic cleaning, and the cleaning reagent is preferably water or absolute ethyl alcohol; the power of the ultrasonic cleaning is preferably 100 to 500W, more preferably 200 to 400W, and still more preferably 300W; the time of ultrasonic cleaning is preferably 15 to 60 minutes, more preferably 25 to 50 minutes, and still more preferably 35 to 40 minutes.
In the invention, ultrasonic cleaning is used for removing impurities such as organic matters on the surface of the tungsten wire electrode.
The structure of the high-temperature furnace used for carrying out electrolysis on the molten oxide electrolyte is shown in fig. 1, wherein 1 is a boron nitride crucible, 2 is a tube furnace, 3 is a refractory brick, 4 is a water-cooling flange, 5 is a corundum tube, 6 is a working electrode, 7 is a reference electrode, 8 is a counter electrode, 9 is an air outlet, and 10 is an air inlet.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
In the examples, siO 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The tailings are the rest components of the tailings after iron separation of the bayan obo ores.
Example 1
42g of SiO 2 、25g CaO、20g CaF 2 And 13g Fe 2 O 3 In an argon atmosphere (flow rate of argon was 0.4m 3 And/h) mixing, fully grinding in an agate mortar, heating to 200 ℃ at the speed of 4 ℃/min, and drying at 200 ℃ for 32h for dehydration treatment to obtain the molten oxide electrolyte.
The tail end of a tungsten wire with the diameter of 2mm and the purity of 98.5 percent is sequentially polished by 200-mesh, 400-mesh, 600-mesh, 800-mesh, 1000-mesh and 1200-mesh sand paper, then soaked in 15 mass percent dilute hydrochloric acid for 2.5 hours, finally ultrasonically cleaned by absolute ethyl alcohol for 50 minutes, and the power of ultrasonic cleaning is 300W. The treated tungsten filament was used as a cathode and graphite was used as an anode (the area ratio of anode to cathode was 8:1).
Heating the high temperature furnace to 1400 ℃ at a speed of 5 ℃/min, preserving the temperature of the molten oxide electrolyte at 1400 ℃ for 40min, and then introducing the molten oxide electrolyte with the density of 0.6A/cm 2 The molten oxide electrolyte was electrolyzed for 5 hours at a reduction potential of 0.45V under an argon atmosphere. And after the electrolysis is finished, slowly cooling the melt along with a furnace, taking out the solidified electrolyte in the boron nitride crucible after the temperature is reduced to the room temperature, and obtaining metallic iron at the bottom of the electrolyte.
The product obtained in this example is shown in FIG. 2, and it can be seen from FIG. 2 that the metallic iron is spherically concentrated at the bottom of the melt, indicating that the metallic iron is uniformly obtained.
The XRD pattern of the product obtained in this example is shown in FIG. 3, and as can be seen from FIG. 3, the product obtained in this example was successfully prepared to obtain metallic iron.
Example 2
45g of SiO 2 、23g CaO、22g CaF 2 And 10g Fe 2 O 3 In a nitrogen atmosphere (flow rate of nitrogen is 0.35m 3 And/h) mixing, fully grinding in an agate mortar, heating to 170 ℃ at a speed of 3 ℃/min, and drying at 170 ℃ for 40h for dehydration treatment to obtain the molten oxide electrolyte.
The tail end of a tungsten wire with the diameter of 1.5mm and the purity of 99.95 percent is sequentially polished by 200-mesh, 400-mesh, 600-mesh, 800-mesh, 1000-mesh and 1200-mesh sand paper, then soaked in diluted hydrochloric acid with the mass fraction of 12 percent for 3 hours, finally ultrasonically cleaned by absolute ethyl alcohol for 30 minutes, and the power of ultrasonic cleaning is 400W. The treated tungsten filament was used as a cathode and graphite was used as an anode (the area ratio of anode to cathode was 7:1).
Heating the high temperature furnace to 1320 ℃ at the speed of 4.5 ℃/min, preserving the temperature of the molten oxide electrolyte at 1320 ℃ for 80min, and then introducing the molten oxide electrolyte with the density of 1.2A/cm 2 The molten oxide electrolyte was electrolyzed for 7 hours at a reduction potential of 0.5V under a nitrogen atmosphere. And after the electrolysis is finished, slowly cooling the melt along with a furnace, taking out the solidified electrolyte in the boron nitride crucible after the temperature is reduced to the room temperature, and obtaining metallic iron at the bottom of the electrolyte.
The product obtained in this example is shown in FIG. 4, and it can be seen from FIG. 4 that the metallic iron is spherically concentrated at the bottom of the melt, indicating that the metallic iron is uniformly obtained.
The XRD pattern of the product obtained in this example is shown in FIG. 5, and as can be seen from FIG. 5, metallic iron was successfully obtained in this example.
Example 3
40g of SiO 2 、25g CaO、30g CaF 2 And 5g Fe 2 O 3 In an argon atmosphere (flow rate of argon was 0.45m 3 And/h) mixing, fully grinding in an agate mortar, heating to 220 ℃ at a speed of 5 ℃/min, and drying at 220 ℃ for 30h for dehydration treatment to obtain the molten oxide electrolyte.
The tail end of a tungsten wire with the diameter of 2.5mm and the purity of 99.99 percent is sequentially polished by 200-mesh, 400-mesh, 600-mesh, 800-mesh, 1000-mesh and 1200-mesh sand paper, then soaked in 17 mass percent dilute hydrochloric acid for 2 hours, finally ultrasonically cleaned by water for 40 minutes, and the power of ultrasonic cleaning is 200W. The treated tungsten filament was used as a cathode and platinum was used as an anode (the area ratio of anode to cathode was 7.5:1).
Heating the high temperature furnace to 1450 ℃ at the speed of 4.5 ℃/min, preserving the temperature of the molten oxide electrolyte at 1450 ℃ for 90min, and then introducing the molten oxide electrolyte with the density of 0.8A/cm 2 Is to the cathodic current of the molten oxide electrolyte8h, the reduction potential of the electrolysis was 0.2V, and the electrolysis was performed under an argon atmosphere. And after the electrolysis is finished, slowly cooling the melt along with a furnace, taking out the solidified electrolyte in the boron nitride crucible after the temperature is reduced to the room temperature, and obtaining the ferrosilicon alloy at the bottom of the electrolyte.
The EDX spectrum of the ferrosilicon alloy prepared in the embodiment is shown in figure 6.
Example 4
43g of SiO 2 、22g CaO、27.5g CaF 2 And 7.5g Fe 2 O 3 In an argon atmosphere (flow rate of argon was 0.4m 3 And/h) mixing, fully grinding in an agate mortar, heating to 220 ℃ at the speed of 4 ℃/min, and drying at 220 ℃ for 35h for dehydration treatment to obtain the molten oxide electrolyte.
The tail end of a tungsten wire with the diameter of 2mm and the purity of 99.9 percent is sequentially polished by 200-mesh, 400-mesh, 600-mesh, 800-mesh, 1000-mesh and 1200-mesh sand paper, then soaked in 15 mass percent dilute hydrochloric acid for 2.5 hours, finally ultrasonically cleaned by absolute ethyl alcohol for 60 minutes, and the power of ultrasonic cleaning is 300W. The treated tungsten filament was used as a cathode and iridium was used as an anode (the area ratio of anode to cathode was 9:1).
Heating a high temperature furnace to 1470 ℃ at a speed of 5.5 ℃/min, preserving the temperature of the molten oxide electrolyte at 1470 ℃ for 100min, and then introducing the molten oxide electrolyte with the density of 1.6A/cm 2 The molten oxide electrolyte was electrolyzed for 10 hours at a reduction potential of 0.1V under an argon atmosphere. And after the electrolysis is finished, slowly cooling the melt along with a furnace, taking out the solidified electrolyte in the boron nitride crucible after the temperature is reduced to the room temperature, and obtaining the ferrosilicon alloy at the bottom of the electrolyte.
The EDX spectrum of the ferrosilicon alloy prepared in the embodiment is shown in figure 7.
The method takes the residual components of the tailings after the iron separation of the bayan obo ores as raw materials, tungsten wires as cathodes and inert materials as anodes, and can realize the further direct extraction of the residual iron ores in the tailings by deeply extracting the residual iron ores in the tailings. The method of the invention not only has higher deposition efficiency, but also has short flow and low energy consumption; the whole process adopts the protective gas for protection, thereby greatly improving the safety of the working procedure, reducing the emission of greenhouse gas and being relatively friendly to the environment.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (9)
1. A method for preparing metallic iron and ferrosilicon alloy by electrolysis of a molten oxide fluoride system, which is characterized by comprising the following steps:
1) SiO is carried out under the atmosphere of protective gas 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 Grinding and drying are sequentially carried out after mixing, so as to obtain a molten oxide electrolyte;
2) And (3) electrolyzing the molten oxide electrolyte by taking a tungsten wire as a cathode and an inert material as an anode to obtain liquid metal iron and ferrosilicon alloy.
2. The method according to claim 1, wherein step 1) the SiO 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The mass ratio of (2) is 40-50: 20-30: 10-30: 5 to 20.
3. The method according to claim 1 or 2, characterized in that the SiO of step 1) is 2 、CaO、CaF 2 And Fe (Fe) 2 O 3 The residual components of tailings after iron separation of the bayan obo ores; the flow rate of the protective gas is 0.3-0.5 m 3 /h。
4. The method according to claim 1 or 2, wherein the drying temperature in step 1) is 160-240 ℃, the drying time is 30-50 h, and the heating rate from the heating to the drying temperature is 2-6 ℃/min.
5. The method according to claim 4, wherein the temperature of the electrolysis in step 2) is 1200-1600 ℃, and the temperature rising rate from the temperature rising to the electrolysis temperature is 4-6 ℃/min.
6. The method according to claim 4, wherein the electrolysis is performed by supplying current after the heat preservation at the electrolysis temperature for 30 to 150 minutes and the electrolysis time for 1 to 15 hours.
7. The method according to claim 5 or 6, wherein during the electrolysis of step 2), the current density is 0.1-2.5A/cm 2 The area ratio of the anode to the cathode is 5-10: 1.
8. the method of claim 7, wherein the inert material of step 2) is graphite, platinum rhodium, or iridium.
9. The method according to claim 8, wherein in step 2) liquid metallic iron is obtained at a reduction potential of 0.3-0.6V; when the reduction potential of electrolysis is 0-0.3V, the ferrosilicon alloy is obtained.
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