Method and device for synchronously carrying out electrolysis iron making and product purification of iron ore concentrate powder

Abstract

The invention belongs to the technical field of iron mineral resource utilization and metallurgy, and particularly relates to a method and a device for synchronously carrying out iron production through electrolysis of iron ore concentrate powder and product purification. According to the method, a fused salt system composed of iron ore concentrate powder, calcium oxide and calcium chloride serves as an electrolyte, a double-cathode single-anode electrolysis system is constructed, electrolytic iron making and product purification are synchronously carried out under inert atmosphere protection through the circulating electrolysis and cathode lifting technology, the traditional iron making technological process is greatly shortened, cost is reduced, and the method is suitable for industrial production. The electrolytic efficiency reaches 88% or above, side reactions in the electrolytic process are few, compared with a traditional ironmaking process, the electrolytic efficiency is high, other impurity metal elements can be effectively removed through high-temperature molten salt electrolysis, an iron product with the purity of 98% or above is obtained, the reaction process is environmentally friendly, no harmful substance is discharged, and pollution is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of iron mineral resource utilization and metallurgy, and more specifically relates to a method and device for simultaneously performing iron production by electrolysis of iron ore powder and product purification. Background Art

[0002] The main steel production method is a long process of "sintering-ironmaking-steelmaking-rolling". The long process of steelmaking uses iron ore, coking coal, etc. as raw materials, and goes through processes such as ore dressing, coking, and ironmaking to obtain molten steel, which is then refined, cast, rolled, and other processes to finally obtain steel products. A large amount of waste gas, wastewater, and solid waste will be generated during the long process of steelmaking. If not handled properly, it will cause great pollution to the environment. In addition, the production process requires a large amount of energy, including coal, electricity, etc., which makes its energy consumption high. It can be seen that improving existing processes and innovating new processes and new technologies are the only way for the steel industry to achieve green transformation, energy conservation, and carbon reduction. How to provide a green, environmentally friendly, efficient, and low-carbon short-process ironmaking method has become a difficult problem that technicians in this field need to overcome.

[0003] Molten salt electrolysis has become one of the options for improved technical solutions due to its green, environmentally friendly, high-efficiency and low-carbon characteristics. However, the adhesion of molten salt in the electrolysis product makes it difficult to separate it from the electrolysis product iron, resulting in the electrolysis product containing a large amount of molten salt components. In addition, industrial continuous production needs to solve the problem of long-term accumulation of electrodeposited impurities in the molten salt, which requires the purification or replacement of the molten salt in the middle, which further limits its application. Summary of the invention

[0004] The object of the present invention is to provide a method and device for simultaneously carrying out electrolytic iron production and product purification by iron ore powder. Specifically, the method uses iron ore powder as raw material, and realizes the method of preparing pure iron by slowly lifting electrodes to realize electrolytic iron production and product purification simultaneously, thereby realizing the green, environmentally friendly, efficient and low-carbon short-process preparation of pure iron.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a method for purifying the product of electrolytic iron production of iron ore powder, the steps comprising:

[0007] An electrolysis system is constructed using a molten salt system consisting of iron ore powder, calcium oxide and calcium chloride as an electrolyte. Iron is electrolyzed under the protection of an inert atmosphere. After the electrolysis is completed, the cathode is removed from the electrolyte at a rate of 1 mm / 10 min.

[0008] Furthermore, the electrolysis system is a multi-cathode single-anode electrolysis system. During electrolysis, one of the cathodes is used for electrolytic iron production. After the electrolysis of one cathode is completed, the cathode that has completed the electrolysis is raised to the electrolyte liquid surface at a rate of 1 mm / 10 min, and at the same time, the other cathode is lowered below the electrolyte liquid surface, and the electrolytic iron production process of the previous cathode is repeated, so that electrolytic iron production and product purification are carried out simultaneously.

[0009] Furthermore, the mass ratio of iron ore concentrate powder, calcium oxide and calcium chloride in the molten salt system is 8:(1.1-12):100.

[0010] Furthermore, the electrodes used in the electrolysis system are graphite rods and / or iron rods.

[0011] Optionally, the electrodes are used as cathodes and anodes after being polished, ultrasonically cleaned, and dried.

[0012] Furthermore, before electrolytic iron making, the electrolyte is heated to 500°C at a heating rate of 4°C / min, kept warm for 3 hours, and then continued to be heated to 800-1000°C and kept warm for 6 hours.

[0013] Furthermore, the electrolytic iron making is constant pressure electrolysis.

[0014] Optionally, the constant voltage is 1.0-2.5V.

[0015] Optionally, the electrolysis time is 2 to 6 hours.

[0016] Furthermore, the inert atmosphere includes an argon atmosphere or a nitrogen atmosphere.

[0017] Optionally, the inert atmosphere is an argon atmosphere.

[0018] Furthermore, after the electrolysis is completed, the cathode is also cleaned and dried.

[0019] Optionally, the cleaning is performed using deionized water and ethanol.

[0020] The second technical solution of the present invention is to provide a device for implementing the above method, comprising:

[0021] A heating system, comprising a heating device, a quartz tube and an electrolytic cell, wherein the quartz tube is placed inside the heating device, the electrolytic cell is placed at the bottom of the quartz tube, and a plurality of through holes are arranged at the top of the quartz tube;

[0022] The electrolysis system comprises an anode, a first cathode, a second cathode, an electrode extraction device and a molten salt system. The anode, the first cathode and the second cathode extend into the electrolysis cell through the through hole and are connected to the molten salt system. The first cathode and the second cathode are controlled to rise and fall by the electrode extraction device.

[0023] The present invention discloses the following technical effects:

[0024] The present invention uses iron ore concentrate powder as raw material and directly electrolyzes pure iron from ore powder molten salt, which greatly shortens the traditional ironmaking process and reduces costs. The electrolysis efficiency reaches more than 88%, and there are fewer side reactions in the electrolysis process. Compared with the traditional ironmaking process, the electrolysis efficiency is high. Other impurity metal elements can be effectively removed through high-temperature molten salt electrolysis to obtain an iron product with a purity of more than 98%. The reaction process is green and environmentally friendly, without any harmful substances discharged, and the generation of pollution is avoided.

[0025] The present invention adopts a method of slowly lifting the electrode, utilizing the temperature in the furnace to exceed the melting point of calcium chloride, and slowly lifting the electrode to separate the molten calcium chloride from the product, thereby achieving simultaneous electrolytic production and product purification, improving the problem of iron dendrite products adhering to molten salt and being difficult to clean, and improving production efficiency.

[0026] The morphology of the electrolysis product of the present invention is controllable, and the precise control of the product morphology from powder to film can be achieved by regulating the electrolysis parameters (voltage, electrolysis time). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 A molten salt electrolysis device;

[0029] The above drawings include the following reference numerals:

[0030] 1-through hole; 2-anode; 3-heating device; 4-electrode extraction device; 5-first cathode; 6-second cathode; 7-quartz tube; 8-molten salt system; 9-electrolytic cell.

[0031] Figure 2 This is a physical picture of the electrolysis product after the simultaneous electrolysis of iron ore powder to produce iron and product purification in Example 1, wherein a is before separation from the cathode, and b is after separation from the cathode.

[0032] Figure 3 This is a physical picture of the electrolysis product after the electrolysis in Comparative Example 1 is completed, wherein a is before separation from the cathode, and b is after separation from the cathode.

[0033] Figure 4 2 are XRD diagrams of the electrolysis products of Example 1 and Comparative Example 1.

[0034] Figure 5 This is the EDS spectrum of the electrolysis product of Example 1, where a is the microscopic morphology, b is the EDS spectrum of iron, and c is the EDS spectrum of calcium.

[0035] Figure 6 This is the EDS spectrum of the electrolysis product of Comparative Example 1, where a is the microscopic morphology, b is the EDS spectrum of iron, and c is the EDS spectrum of calcium.

[0036] Figure 7 This is a physical picture of the electrolysis product in Example 2, where a is before separation from the cathode and b is after separation from the cathode.

[0037] Figure 8 This is the EDS energy spectrum of the electrolysis product of Example 2, where a is the microscopic morphology, b is the EDS energy spectrum of iron, and c is the EDS energy spectrum of calcium.

[0038] Fig. 9 This is the curve showing the effect of CaO addition on the iron ion content in the molten salt. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0042] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0043] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0044] In a specific embodiment of the present invention, an iron rod with a diameter of 1.5 mm is used as a guide wire, and an iron-chromium-aluminum wire with a diameter of 0.2 mm is used to connect the cathode and the anode to the guide wire.

[0045] Unless otherwise specified, the "room temperature" or "normal temperature" in the specific embodiments of the present invention refers to 20-30°C.

[0046] The molten salt electrolysis device used in the specific embodiment of the present invention is as follows Figure 1 As shown. Among them, Figure 1 The figures in the figure are marked as follows: 1-through hole; 2-anode; 3-heating device; 4-electrode extraction device; 5-first cathode; 6-second cathode; 7-quartz tube; 8-molten salt system; 9-electrolytic cell.

[0047] The main chemical components of the iron ore concentrate powder used in the specific embodiment of the present invention are shown in Table 1.

[0048] Table 1

[0049]

[0050] Example 1

[0051] use Figure 1 The device shown in the figure performs electrolysis of iron concentrate powder to produce iron and product purification simultaneously, and the steps include:

[0052] S1. Dry the iron ore concentrate at 90° C. and then ball-mill for 6 hours. Weigh 8 g of the ball-milled iron ore concentrate, 8 g of CaO, and 100 g of anhydrous calcium chloride and mix them evenly to prepare a molten salt system.

[0053] S2. The molten salt system prepared in S1 is loaded into a corundum crucible, and high-purity argon (99.9999%) is used as a protective gas in a box-type resistance furnace, and the temperature is increased to 500°C at a heating rate of 4°C / min for 3 hours to remove crystal water, and then the temperature is further increased to 850°C and kept for 6 hours, and a graphite cathode and a graphite anode are placed in the crucible for pre-electrolysis at a constant voltage of 1.5V for 1 hour, and then the cathode is removed to complete the pre-electrolysis;

[0054] S3. After the pre-electrolysis is completed, two graphite cathodes are prepared, one of which is inserted 2 cm below the molten salt surface and electrolyzed for 3 hours at a constant voltage of 1.5 V. The other cathode is kept on standby above the molten salt. When the electrolysis of the first cathode is completed, this cathode is inserted 2 cm below the molten salt surface and the subsequent electrolysis is started at a constant voltage of 1.5 V. The cathode that has completed the first electrolysis is slowly raised at a speed of 1 mm / 10 min until it leaves the molten salt surface. At this time, the cathode that is currently electrolyzing has completed the electrolysis work and starts to be slowly raised. The operation is repeated to achieve simultaneous electrolytic iron making and product purification. The actual picture of the purified cathode is as follows: Figure 2 As shown;

[0055] S4. The cathode that has completed the electrolysis work is cleaned with deionized water and ethanol ultrasonically, and then dried at low temperature (90° C.) to obtain an electrolysis product.

[0056] After weighing, 1.40 g of product was obtained by constant voltage electrolysis at 1.5 V for 3 h, and the average current was 0.725 A. According to the current efficiency calculation formula (Formula 1):

[0057]

[0058] The calculated current efficiency is: 88.89% (in Formula 1, η is the current efficiency, %; m is the mass of the product, g; I is the current, A; t is the time, h; k is the electrochemical equivalent of iron, 0.7241 g A·h -1 ).

[0059] Example 2

[0060] Compared with Example 1, the only difference is that the constant voltage of electrolysis is adjusted from 1.5V to 1.0V. The actual picture of the electrolysis product is as follows: Figure 7 shown.

[0061] Figure 7 This is a physical picture of the electrolysis product in Example 2, where a is before separation from the cathode, and b is after separation from the cathode. It can be seen from the figure that the iron product of 1.0V constant voltage electrolysis is an iron film deposition with a silvery white metallic luster, without obvious iron dendrite morphology.

[0062] The product mass was weighed to be 0.08 g, the average current was 0.04 A under a constant voltage of 1.0 V, and the current efficiency was calculated to be 92.07%.

[0063] Figure 8 The EDS spectrum of the electrolysis product of Example 2, where a is the microscopic morphology, b is the EDS spectrum of iron, and c is the EDS spectrum of calcium. Figure 8 It can be seen that the morphology of the electrolysis products can be controlled by adjusting the electrolysis parameters.

[0064] Comparative Example 1

[0065] The steps of electrolyzing iron ore powder to produce iron include:

[0066] S1. Dry the iron ore concentrate at 90°C and then ball-mill for 6 hours. Weigh 5g of the ball-milled iron ore concentrate and mix it with 8g of CaO and 87g of anhydrous calcium chloride to prepare a molten salt system.

[0067] S2. The molten salt system prepared in S1 is loaded into a corundum crucible, and high-purity argon (99.9999%) is used as a protective gas in a box-type resistance furnace, and the temperature is increased to 500°C at a heating rate of 4°C / min for 3 hours to remove crystal water, and then the temperature is further increased to 850°C and kept for 6 hours, and a graphite cathode and a graphite anode are placed in the crucible for pre-electrolysis at a constant voltage of 1.5V for 1 hour, and then the cathode is removed to complete the pre-electrolysis;

[0068] S3. After the pre-electrolysis is completed, prepare a new graphite cathode, insert it 2 cm below the molten salt liquid surface, and electrolyze for 3 h at a constant voltage of 1.5 V. After the electrolysis is completed, take out the cathode immediately;

[0069] S3. The cathode that has completed the electrolysis work is cleaned with deionized water and ethanol ultrasonically, and then dried at low temperature (90° C.) to obtain an electrolysis product.

[0070] Figure 2 This is a physical picture of the electrolysis product after the simultaneous electrolysis of iron ore powder to produce iron and product purification in Example 1, wherein a is before separation from the cathode, and b is after separation from the cathode; Figure 3 This is a physical picture of the electrolysis product after the electrolysis in Comparative Example 1 is completed, where a is before separation from the cathode, and b is after separation from the cathode. Figure 2-3 As shown, it can be found that the electrolysis product of Example 1 has significantly less sticky molten salt than the electrolysis product of Comparative Example 1, and an obvious iron dendrite structure can be seen. The electrolysis product of Comparative Example 1 has obvious calcium chloride molten salt sticking to its surface, which is difficult to clean.

[0071] Figure 4 The XRD diagrams of the electrolysis products of Example 1 and Comparative Example 1 show that obvious Fe peaks are detected, indicating the feasibility of the molten salt electrolysis iron-making scheme.

[0072] Figure 5 The EDS spectrum of the electrolysis product of Example 1, wherein a is the microscopic morphology, b is the EDS spectrum of iron, and c is the EDS spectrum of calcium; Figure 6 The EDS spectrum of the electrolysis product of Comparative Example 1, wherein a is the microscopic morphology, b is the EDS spectrum of iron, and c is the EDS spectrum of calcium. Figure 5-6 It can be seen that the calcium content of the electrolysis product of Example 1 using the technical solution of the present invention is significantly reduced.

[0073] Test example

[0074] In order to explore the effect of different CaO addition amounts in the molten salt system on the solubility of iron ore in molten calcium chloride, 1.1g (1wt.%), 2.2g (2wt.%), 3.3g (3wt.%), 4.5g (4wt.%), 5.7 (5wt.%), 9.4g (8wt.%), and 12g (10wt.%) of calcium oxide were added to the system of 8g iron concentrate powder + 100g CaCl2 to form a molten salt system. Under the argon protective atmosphere in the furnace, the temperature was raised to 500℃ at a heating rate of 4℃ / min and kept for 3h to remove the crystallization water. The temperature was continued to be raised to 850℃ at 4℃ / min and kept for 12h to make the composition in the molten salt system uniform. After 12h, the upper half of the molten salt was dipped with a graphite electrode and dried in a vacuum drying oven. After ICP detection, the content of iron ions in the molten salt with different CaO addition amounts was determined. The results are as follows Fig. 9 shown.

[0075] Fig. 9 The figure is the influence curve of CaO addition on the iron ion content in the molten salt. It can be seen from the figure that with the increase of CaO addition, the iron ion content in the molten salt gradually increases, and when the CaO content is 8wt.%, compared with the addition of 1wt.%, the iron ion content increases from 0.07wt.% to 0.55wt.%, and when the CaO content is added to 10wt.%, the iron ion content increases to 0.57%, and the increase is not large, so it is appropriate to add CaO to 8wt.%.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying iron ore electrolysis products, characterized in that: An electrolysis system is constructed using a molten salt system consisting of iron ore powder, calcium oxide and calcium chloride as an electrolyte. Iron is electrolyzed under the protection of an inert atmosphere. After the electrolysis is completed, the cathode is removed from the electrolyte at a rate of 1 mm / 10 min.

2. The method for purifying the product of electrolytic ironmaking by iron concentrate powder according to claim 1, characterized in that: The electrolysis system is a multi-cathode single-anode electrolysis system. During electrolysis, one of the cathodes is used for electrolytic iron production. After the electrolysis of one cathode is completed, the cathode that has completed electrolysis is lifted to the electrolyte liquid surface at a rate of 1 mm / 10 min, and at the same time, the other cathode is lowered below the electrolyte liquid surface, and the electrolytic iron production process of the previous cathode is repeated, so that electrolytic iron production and product purification are carried out simultaneously.

3. The method according to claim 1, characterized in that The mass ratio of iron ore concentrate powder, calcium oxide and calcium chloride in the molten salt system is 8:(1.1-12):

100.

4. The method according to claim 1, characterized in that The electrodes used in the electrolysis system are graphite rods and / or iron rods.

5. The method according to claim 1, characterized in that Before electrolytic iron making, the electrolyte is heated to 500°C at a heating rate of 4°C / min, kept at this temperature for 3 hours, and then continued to be heated to 800-1000°C and kept at this temperature for 6 hours.

6. The method according to claim 1, characterized in that The electrolytic iron making is constant voltage electrolysis, the constant voltage is 1.0-2.5V; and / or, The electrolysis time is 2 to 6 hours.

7. The method according to claim 1, characterized in that The inert atmosphere includes an argon atmosphere or a nitrogen atmosphere.

8. The method according to claim 1, characterized in that After the electrolysis is completed, the cathode is also cleaned and dried.

9. A device for implementing the method according to any one of claims 1 to 8, characterized in that: include: A heating system, comprising a heating device (3), a quartz tube (7) and an electrolytic cell (9), wherein the quartz tube (7) is placed inside the heating device (3), the electrolytic cell (9) is placed at the bottom of the quartz tube (7), and a plurality of through holes (1) are provided at the top of the quartz tube (7); An electrolysis system comprises an anode (2), a first cathode (5), a second cathode (6), an electrode extraction device (4) and a molten salt system (8); the anode (2), the first cathode (5) and the second cathode (6) extend through the through hole (1) into the electrolysis cell (9) and are connected to the molten salt system (8); the first cathode (5) and the second cathode (6) are controlled to rise and fall by the electrode extraction device (4).

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