Electrolytic iron metal production equipment

Abstract

An apparatus (1) for the production of ferrous metals through the reduction of iron ore by electrolytic reaction, the apparatus comprising a pump device (22) located at one end of a casing (4) and an electrolyte circulation device (30) including at least a first (31A) check valve located in the electrolyte chamber (6) and a second (31B) check valve located in the gas recovery section (8), said electrolyte circulation device (30) being designed to suck electrolyte (5) from the electrolyte chamber (6) or to draw electrolyte (5) back to the gas recovery section (8) when actuated by an actuator (28).

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing ferrous metal from iron oxide by an electrolytic process. [Background technology]

[0002] Currently, steel can be produced on an industrial scale through two main production routes. The most commonly used production route today is by producing pig iron in a blast furnace by using a reducing agent, primarily coke, to reduce iron oxide. This process consumes approximately 450 to 600 kg of coke per metric ton of pig iron, and the process releases significant amounts of CO2, both in the production of coke from coal in the coking plant and in the production of pig iron.

[0003] The second main route involves the so-called "direct reduction process." Among them are processes under the brands MIDREX, FINMET, ENERGIRON / HYL, COREX, FINEX, etc., in which sponge iron is produced by direct reduction of an iron oxide support in the form of HDRI (high-temperature direct reduced iron), CDRI (low-temperature direct reduced iron), or HBI (high-temperature briquetted iron). Sponge iron in the form of HDRI, CDRI, and HBI is usually further processed in an electric arc furnace. Even though this second route emits less CO2 than the previous one, it still emits some and relies on carbon-rich fossil fuels.

[0004] Current developments are therefore focused on methods that make it possible to produce iron that emits less or no CO2 and is carbon neutral.

[0005] An alternative known method for producing steel from iron ore consisting of iron oxide is based on electrochemical technology. In such technology, iron is produced from iron oxide using an electrolysis unit comprising two electrodes (anode and cathode) connected to a current source, an electrolyte circuit, and iron oxide entering the electrolysis unit. The anode and cathode are constantly immersed in a circulating electrolyte to ensure good electrical conduction between the electrodes. The electrolysis reaction produces pure iron plates on the cathode and gaseous oxygen at the anode. The iron plates thus obtained can then be melted in an electric furnace with other elements, such as a carbon source and scrap, to produce steel.

[0006] To limit the environmental footprint of the process, the electrolyte is recirculated within the cell to limit the need for fresh electrolyte. To achieve this, external pumps are currently used between the electrolyte inlet and outlet of the electrolysis cell. These pumps consume energy and induce heat losses, making the process very energy-intensive and associated with high operating costs that make upscaling to high production rates difficult. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to remedy the shortcomings of the prior art by providing an electrochemical iron production system with improved energy efficiency. [Means for solving the problem]

[0008] To this end, the present invention relates to an apparatus for the production of ferrous metals through the reduction of iron ore by electrolysis, the apparatus comprising a casing including a gas-permeable anode plate and a cathode plate, both of which face each other and are separated by an electrolyte chamber, the casing being provided with means for supplying electrolyte into the chamber and means for supplying iron ore to said chamber, the casing further comprising a degassing unit, the degassing unit comprising a gas recovery section extending along the opposite side of the anode plate from the chamber, and an electrolyte recirculation section extending continuously from the gas recovery section to a gas outlet and in fluid connection with the chamber, the apparatus further comprising an electrolyte circulation device comprising a pump device located at one end of the casing, a first non-return device located in at least the electrolyte chamber, and a second non-return device located in the gas recovery section, the electrolyte circulation device being designed to suck electrolyte from the electrolyte chamber or to draw electrolyte back into the gas recovery section when actuated by an actuator.

[0009] The device may also include the following optional features, taken into account by the techniques individually or in all possible combinations: the pumping device is located at the end of the casing opposite the electrolyte supply means; the pumping device is located outside the casing but in fluid connection with the casing; the pumping device is partially located inside the casing, - the non-return device is an elastic membrane made of an electrically insulating material, - the elastic membrane is made of ethylene propylene diene monomer, - the check device is a mechanical valve made of electrically insulating material; the actuator is a hydraulic actuator; The device is powered by renewable energy.

[0010] Other features and advantages of the present invention will become apparent in the following description, given by way of indication and in no way limiting, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0011] [Figure 1A] 1 is a longitudinal section of the device according to the invention, with the electrolyte circulation device in suction mode; FIG. [Figure 1B] 1 is a longitudinal section of an apparatus according to the invention, with the electrolyte circulation device in pull-back mode; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] First, it should be noted that in the figures, the same reference numerals refer to the same elements regardless of the figure they feature in and regardless of the shape of those elements. Similarly, if elements are not specifically referenced in one of the figures, their reference can be easily found by referring to another figure.

[0013] It should also be noted that the figures primarily represent one embodiment of the subject matter of the invention, but other embodiments may exist that correspond to the definition of the invention. The elements in the figures are illustrative and may not be drawn to scale.

[0014] The present invention refers to an apparatus 1 provided for the production of iron metal (Fe) through the reduction of iron ore, particularly containing hematite (FeO) and other iron oxides or hydroxides, by electrolytic reaction. The chemical reaction is well known and can be described by the following equation (1):

number

[0015] It is therefore believed that the electrolysis reaction releases gases - primarily oxygen - which must be extracted from the device 1 .

[0016] 1A and 1B, the apparatus 1 or electrolysis cell comprises a casing 4 extending along a longitudinal axis X along which the electrolysis reaction takes place. The casing 4 is defined by a base plate 16, a cover plate 17, and two side plates 24. In addition, the casing comprises a gas-permeable anode plate 2 intended to be fully immersed in an electrolytic solution (electrolyte) 5, and a cathode plate 3, both plates facing each other and held at the required distance by fastening means (not shown). The casing 4 also comprises an electrolyte chamber 6 extending longitudinally between the anode plate 2 and the cathode plate 3 to an exhaust chamber 27. The apparatus 1 finally comprises a power supply (not shown) connected to the anode plate 2 and the cathode plate 3.

[0017] To produce iron metal through an electrolysis reaction, an electrolyte 5, preferably an aqueous solution such as aqueous sodium hydroxide, flows through the casing 4 within the electrolyte chamber 6 while the apparatus 1 is in operation. Accordingly, the apparatus 1 includes an inlet 18 managed by the casing 4 that is fluidly connected to the electrolyte chamber 6. Iron ore is preferentially fed into the apparatus 1 as a powder suspension in the electrolyte 5 through the inlet 18.

[0018] During the electrolysis reaction, iron oxide is reduced to iron metal by reaction (1), and the reduced iron is deposited on the cathode plate 3, while gaseous oxygen is produced. As mentioned above, gases are produced inside the casing 4. These gases are electrical insulators and therefore interfere with the successful operation of the electrolysis reaction, and are therefore continuously vented outside the casing 4.

[0019] For this purpose, the casing 4 contains a degassing unit 7 with a gas recovery section 8 extending longitudinally along the side 23 opposite the anode plate 2 from the electrolyte chamber 6. This gas recovery section 8 is a compartment arranged to be filled with the electrolyte 5 and located between the anode plate 2 and the cover plate 17. The gas recovery section 8 is therefore arranged to recover the gases (dioxygen and dihydrogen) leaking through the anode plate 2.

[0020] 1A and 1B, the degassing unit 7 also includes an electrolyte recirculation section 9, which extends continuously with the gas recovery section 8 to a gas outlet 10 managed by the casing 4. The electrolyte recirculation section 9 is configured to be at least partially filled with electrolyte 5. In addition, the recirculation section 9 is fluidly connected to the electrolyte chamber 6. When the device 1 is in operation, the recirculation section 9 allows the electrolyte 5 flowing from the gas recovery section 8 to be preferentially redirected toward the electrolyte chamber 6 via an elbow duct 25 of the electrolyte recirculation section 9 adjacent to the anode plate 2 and fluidly connected to the electrolyte chamber 6. The electrolyte recirculation section 9 includes a gas-liquid partition means (not shown), which preferentially allows for improved separation between the gas exhausted through the gas outlet 10 and the electrolyte recirculated in the electrolyte chamber 6. This gas-liquid partition means may for example be a solid plate extending along the recirculation section 9, provided with perforations for gas-liquid separation.

[0021] In the device 1 according to the present invention, the casing 4 further comprises an electrolyte recirculation device 30, which includes a pumping device 22 and at least two check valves 31A, 31B located at one of its ends. The end location allows the full width of the device to be utilized for pumping, thus increasing the efficiency of recirculation. This can be located outside (not shown) the casing 4, as illustrated in FIGS. 1A and 1B, or at least partially inside. It is preferably located at the bottom 27 of the cell, opposite the electrolyte inlet 21. This pumping device 22 may be a pneumatic membrane pump. It is actuated by an actuator 24, which may be a pneumatic cylinder or a hydraulic actuator.

[0022] Those skilled in the art will know how to size the pumping device and what flow rate and frequency of pumping is required depending on the size of the electrolysis cell to ensure good recirculation of the electrolyte.

[0023] The pump device 22 is associated with at least two check valves 31A, 31B, the first check valve 31A being located in the electrolyte chamber 6 and the second check valve 31B being located in the gas recovery section 8. These check valves 31A, 31B may be elastic membrane or mechanical valves. They are made of an electrically insulating material. If they are membranes, they may be made of ethylene propylene diene monomer (EPDM). They may also be a combination of these different types of devices.

[0024] Next, the operation of the device 1 during the electrolysis reaction will be described.

[0025] The electrolyte 5 circulates continuously in the circuit from the inlet 18 through the electrolyte chamber 6 towards the exhaust chamber 27 thanks to the pumping device 22 and the check valves 31A, 31B. The power supplies connected to both the anode plate 2 and the cathode plate 3 are switched on, and the electrolyte chamber 6 is periodically supplied with iron ore from the means 21 for supplying iron ore to the device 1. The casing 4 is almost filled with the electrolyte 5, as shown in Figures 1A and 1B, with only the gas outlet 10 being free of electrolyte. Under these conditions, the electrolysis reaction can take place.

[0026] The iron ore is reduced and pure iron is deposited on the cathode surface 3 , while the oxygen generated flows together with the electrolyte through the anode plate 2 towards the gas recovery section 8 of the degassing unit 7 .

[0027] The longitudinal axis X is preferably inclined at an angle ranging between 40° and 60°, preferably 50°, relative to the horizontal to allow gas circulation from the gas recovery section 8 towards the electrolyte recirculation section 9 and finally towards the gas outlet 10. The gas outlet 10 is therefore at the highest point of the casing 4 to allow gas evacuation.

[0028] The moving gas circulates through the gas recovery section 8, pumping the electrolyte 5 from said recovery section 8 to the recirculation section 9. The gas flows continuously towards the gas outlet 10, and the electrolyte 5 is forced by gravity into the electrolyte chamber 6 and recirculated in the circuit 20. However, this circulation with the gas is not sufficient to ensure good recirculation of the electrolyte 5. Therefore, the pumping device continuously sucks and pulls back the electrolyte in the device.

[0029] 1A, the first check valve 31A located in the electrolyte chamber 6 is opened and the second check valve 31B located in the gas recovery section 8 is closed. The pumping device 22 is actuated by the actuator 28 to suck the electrolyte 5 from the electrolyte chamber 6.

[0030] 1B, the first check valve 31A located in the electrolyte chamber 6 is closed and the second check valve 31B located in the gas recovery section 8 is open. The pumping device 22 is actuated by the actuator 28 to draw the electrolyte 5 back into the gas recovery section 8. In one preferred embodiment, when the pumping device 22 is located at the bottom of the cell, the drawn-back flow is additive with the flow generated by the buoyancy of the gas escaping through the anode 2.

[0031] It is then possible to recirculate the electrolyte 5 in the electrolyte chamber 6 without causing gas accumulation at the cathode level, thereby eliminating the need to periodically inject a fresh electrolyte flow into the device 1.

[0032] In all of the foregoing embodiments, the apparatus is preferentially powered by renewable energy, which is defined as energy collected from renewable sources that are naturally replenished on human timescales, including sources such as sunlight, wind, rain, tides, waves, and geothermal heat. In some embodiments, the use of nuclear power can be utilized because it does not emit the CO2 produced. This further limits the CO2 footprint of the iron production process.

Claims

1. An apparatus (1) for the production of iron metal through the reduction of iron ore by electrolysis, the electrolysis reaction producing gas, the apparatus comprising a casing (4), the casing (4) containing a gas-permeable anode plate (2) and a cathode plate (3) facing each other and separated by an electrolyte chamber (6); The casing (4) is provided with means for supplying an electrolyte (5) into the chamber (6) and means for supplying iron ore to the chamber (6), The casing (4) further includes a degassing unit, the degassing unit including a gas recovery section (8) extending along the opposite side (23) of the anode plate (2) from the chamber (6), and an electrolyte recirculation section (9) extending continuously from the gas recovery section (8) to the gas outlet (10) and in fluid connection with the chamber (6); The device further comprises an electrolyte circulation device (30) including a pump device (22) located at one end of the casing (4), a first check valve (31A) located in at least the electrolyte chamber (6), and a second check valve (31B) located in the gas recovery section (8), the electrolyte circulation device (30) being designed to suck the electrolyte (5) from the electrolyte chamber (6) or to draw the electrolyte (5) back into the gas recovery section (8) when actuated by an actuator (28). Device.

2. 2. The device according to claim 1, wherein the pumping device (22) is located at the end of the casing (4) opposite the electrolyte (5) supply means.

3. 3. The device according to claim 1 or 2, wherein the pumping device (22) is located outside the casing (4) but is in fluid connection with the casing (4).

4. 3. The device according to claim 1 or 2, wherein the pump device (22) is located partly inside the casing (4).

5. The device according to any one of claims 1 to 4, wherein the check valves (31A, 31B) are elastic membranes made of an electrically insulating material.

6. 6. The device of claim 5, wherein the elastic membrane comprises ethylene propylene diene monomer.

7. The device according to any one of claims 1 to 4, wherein the check valves (31A, 31B) are mechanical valves made of an electrically insulating material.

8. An apparatus according to any one of claims 1 to 7, wherein the actuator (28) is a hydraulic actuator.

9. 9. The device of any one of claims 1 to 8, powered by renewable energy.

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