Preparation method of high-purity iron

Abstract

The invention discloses a preparation method of high-purity iron, which comprises the following steps: dissolving and analyzing pure ferrite by using pure water, and adjusting the pH value to obtain electrolyte; carrying out at least two-stage precise filtration on the electrolyte; carrying out surface treatment on the electrolytic anode; and an anode, a cathode and an electrolyte are used for pre-electrolysis and electrolysis in sequence, and the high-purity iron is obtained. According to the preparation method, the high-purity iron with the purity of 4N-5N can be prepared, the preparation process is simple, the process energy consumption is low, and the preparation method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of metal preparation and relates to a method for preparing high-purity iron. Background Art

[0002] The purity of metals is usually indicated by N (the first letter of the English word nine) and numbers. The purity of general industrial pure iron is 2N5~3N, 3N~4N is called high-purity iron, and 4N and above is ultra-high purity iron. High-purity and ultra-high purity iron have good ductility, corrosion resistance, thermal properties, soft magnetism and electrical conductivity, etc., which can significantly improve the performance and quality of materials such as steel, semiconductors, and amorphous materials, and greatly improve the heat resistance and corrosion resistance of alloys, thereby further promoting the development of aerospace, energy and new semiconductor industries.

[0003] CN114232033A discloses a method for preparing high-purity iron by high-temperature molten salt electrodeposition, which uses CaCl2-Fe2O3-CaO as a molten salt system, and grows high-purity iron materials by molten salt electrodeposition under constant current and constant voltage conditions and an argon inert atmosphere at 850°C. Although this method can prepare high-purity iron by electrolysis in one step, it requires a lot of energy to maintain the electrolysis state during the molten salt heating and electrolysis process, and the preparation cost is high.

[0004] CN 118437931 A discloses a method for preparing high-purity iron powder, comprising: 1) adding blast furnace molten iron treated with three decarburization processes into a converter, and the tapping temperature of the molten steel at the end of blowing is higher than 1750°C, and the active oxygen content is ≥0.085%. 2) The molten steel in the ladle is subjected to RH vacuum oxygen blowing decarburization treatment, and the composition of the molten steel after treatment is [O] ≥0.010%. 3) The ladle is moved to a VD, vacuumized, and left to stand for ≥20 minutes. 4) The molten steel is made into an ingot by a vacuum casting method to obtain an "oxygen-enriched high-purity iron" with an ingot composition of [Fe] + [O] ≥99.99%. 6) The "oxygen-enriched high-purity iron" ingot is made into an "oxygen-enriched high-purity iron fraction". 7) The "oxygen-enriched high-purity iron fraction" is passed through a hydrogen reduction furnace to remove oxygen and obtain a "hydrogen-containing high-purity iron powder". This method prepares high-purity iron powder by smelting, which has a complex preparation process, a smelting temperature higher than 1750°C, high energy consumption and high preparation cost. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a method for preparing high-purity iron, which can prepare high-purity iron with a purity of 4N to 5N. The preparation process is simple, the process energy consumption is low, and it is suitable for industrial production.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing high-purity iron, which comprises the following steps:

[0008] Use pure water to dissolve analytical pure ferrous salt and adjust the pH to obtain an electrolyte;

[0009] Perform at least two stages of precision filtration on the electrolyte;

[0010] Surface treatment of electrolytic anodes;

[0011] The high-purity iron is obtained by sequentially performing pre-electrolysis and electrolysis using an anode, a cathode and an electrolyte.

[0012] As a preferred technical solution of the present invention, the concentration of ferrous ions in the electrolyte is 50-70 g / L.

[0013] As a preferred technical solution of the present invention, the pH of the electrolyte is adjusted to 2-4.

[0014] As a preferred technical solution of the present invention, the precision filtration includes first-stage precision filtration and second-stage precision filtration performed sequentially.

[0015] As a preferred technical solution of the present invention, the filtration accuracy of the first stage precision filtration is 15 to 20 μm, and the filtration accuracy of the second stage precision filtration is 5 to 10 μm.

[0016] As a preferred technical solution of the present invention, the surface treatment of the electrolytic anode includes acid leaching and water washing performed in sequence.

[0017] As a preferred technical solution of the present invention, the surface treatment of the electrolytic cathode includes pickling.

[0018] As a preferred technical solution of the present invention, acid leaching includes immersing in dilute sulfuric acid with a concentration of 0.1 to 0.5 mol / L for not less than 24 hours.

[0019] As a preferred technical solution of the present invention, the pre-electrolysis and electrolysis are carried out under the condition of a vacuum degree of 1 to 100Pa.

[0020] As a preferred technical solution of the present invention, the current density of the pre-electrolysis and electrolysis is independently 50 to 100 A / m 2 .

[0021] As a preferred technical solution of the present invention, the pre-electrolysis time is at least 48 hours.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] The invention provides a method for preparing high-purity iron. The method can prepare high-purity iron with a purity of 4N to 5N, has a simple preparation process, low process energy consumption, and is suitable for industrial production. DETAILED DESCRIPTION

[0024] The technical solution of the present application is further described below through specific implementation methods.

[0025] The specific embodiment of the present invention provides a method for preparing high-purity iron, which comprises the following steps:

[0026] Use pure water to dissolve analytical pure ferrous salt and adjust the pH to obtain an electrolyte;

[0027] Perform at least two stages of precision filtration on the electrolyte;

[0028] Surface treatment of electrolytic anodes;

[0029] The high-purity iron is obtained by sequentially performing pre-electrolysis and electrolysis using an anode, a cathode and an electrolyte.

[0030] In a specific embodiment of the present invention, the concentration of ferrous ions in the electrolyte is 50-70 g / L, such as 50 g / L, 52 g / L, 55 g / L, 58 g / L, 60 g / L, 62 g / L, 65 g / L, 68 g / L or 70 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In one specific embodiment of the present invention, the analytically pure ferrous salt is preferably analytically pure ferrous chloride.

[0032] In a specific embodiment of the present invention, the pH of the electrolyte is adjusted to 2-4, such as 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8 or 4, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In one embodiment of the present invention, the pH value of the electrolyte is adjusted by a base or acid such as ammonia or hydrochloric acid, wherein the base or acid used to adjust the pH value of the electrolyte is analytical grade.

[0034] In a specific embodiment of the present invention, the precision filtration includes a first stage precision filtration and a second stage precision filtration performed sequentially.

[0035] In a specific embodiment of the present invention, the filtration accuracy of the first stage precision filtration is 15 to 20 μm, and the filtration accuracy of the second stage precision filtration is 5 to 10 μm. The filtration accuracy of the first stage precision filtration can be 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc., and the filtration accuracy of the second stage precision filtration can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc., but are not limited to the listed values, and other values ​​not listed within the above numerical ranges are also applicable.

[0036] In one embodiment of the present invention, the surface treatment of the electrolytic anode comprises acid leaching and water washing performed sequentially.

[0037] In a specific embodiment of the present invention, acid leaching includes soaking in dilute sulfuric acid with a concentration of 0.1 to 0.5 mol / L for not less than 24 hours. The concentration of the dilute sulfuric acid may be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L, etc., and the soaking time may be 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours or 48 hours, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are also applicable.

[0038] In a specific embodiment of the present invention, the dilute sulfuric acid is prepared by using analytically pure sulfuric acid and pure water.

[0039] In a specific embodiment of the present invention, pure water is used for water washing to remove the acid solution remaining on the surface of the electrolytic anode.

[0040] In one specific embodiment of the present invention, the surface treatment of the electrolytic cathode includes acid washing.

[0041] In one embodiment of the present invention, the pickling includes cleaning the surface of the electrolytic cathode with analytically pure dilute sulfuric acid to remove oil stains and impurities.

[0042] In a specific embodiment of the present invention, pre-electrolysis and electrolysis are carried out under a vacuum degree of 1 to 100 Pa. The vacuum degree can be 1Pa, 10Pa, 20Pa, 50Pa, 80Pa or 100Pa, etc., but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0043] In one specific embodiment of the present invention, pre-electrolysis and electrolysis are carried out in a bottom pressure electrolysis cell.

[0044] In one embodiment of the present invention, the current density of the pre-electrolysis and the electrolysis is independently 50 to 100 A / m 2 , such as 50A / m 2 、60A / m 2 , 70A / m 2 、80A / m 2 , 90A / m 2 or 100A / m 2 The above range is not limited to the listed values, and other values ​​not listed within the above range are also applicable.

[0045] In a specific embodiment of the present invention, during the electrolysis process, the pH value of the electrolyte is adjusted by adding a base or acid such as ammonia water or hydrochloric acid to stabilize the pH value of the electrolyte at 2-4.

[0046] In a specific embodiment of the present invention, the pre-electrolysis time is at least 48 hours, such as 48 hours, 52 hours, 56 hours, 60 hours, 64 hours, 68 hours or 72 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In a specific embodiment of the present invention, the electrolysis time is not less than 120 hours, such as 120 hours, 150 hours, 180 hours, 210 hours or 240 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In the present invention, the electrolyte is subjected to multi-stage precision filtration treatment to remove possible impurities remaining in the electrolyte as much as possible. Before the electrical connection treatment, the anode and cathode are surface treated to remove impurities in the anode and cathode to avoid the introduction of impurities during the electrolysis process. The compounds used for preparing the electrolyte and adjusting the pH are all analytically pure, and high-purity iron can be directly prepared by electrolysis.

[0049] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] Example 1

[0051] This embodiment provides a method for preparing high-purity iron, the preparation method comprising:

[0052] Use pure water to dissolve analytical pure ferrous chloride, use analytical pure ammonia and hydrochloric acid to adjust the pH of the electrolyte to 2-4, and the concentration of ferrous ions in the electrolyte is 60g / L;

[0053] The electrolyte is subjected to first-stage precision filtration and second-stage precision filtration in sequence, the filtration accuracy of the first-stage precision filtration is 20μm, and the filtration accuracy of the second-stage precision filtration is 5μm;

[0054] The pure iron anode was soaked in 0.2 mol / L dilute sulfuric acid (prepared with analytical grade sulfuric acid and pure water) for 36 hours, and the pure iron anode after acid immersion was cleaned with pure water to remove the residual acid on the surface of the pure iron anode; the cathode of the titanium plate was pickled with analytical grade dilute nitric acid to remove oil stains and impurities;

[0055] Place the anode, cathode and electrolyte into a low-pressure electrolytic cell, maintain the vacuum degree at 1-100 Pa, and the current density at 75 A / m 2 , pre-electrolysis for 48 hours, electrolysis for 120 hours, to obtain the high-purity iron.

[0056] Example 2

[0057] This embodiment provides a method for preparing high-purity iron, the preparation method comprising:

[0058] Use pure water to dissolve analytical pure ferrous chloride, use analytical pure ammonia and hydrochloric acid to adjust the pH of the electrolyte to 2-4, and the concentration of ferrous ions in the electrolyte is 50g / L;

[0059] The electrolyte is subjected to first-stage precision filtration and second-stage precision filtration in sequence, the filtration accuracy of the first-stage precision filtration is 15μm, and the filtration accuracy of the second-stage precision filtration is 10μm;

[0060] Use 0.1 mol / L dilute sulfuric acid (prepared with analytical grade sulfuric acid and pure water) to soak the pure iron anode for 48 hours, and use pure water to clean the pure iron anode after acid leaching to remove the residual acid on the surface of the pure iron anode; use analytical grade dilute nitric acid to pickle the titanium plate cathode to remove oil stains and impurities;

[0061] Place the anode, cathode and electrolyte into a low-pressure electrolytic cell, maintain the vacuum degree at 1-100 Pa, and the current density at 50 A / m 2 , pre-electrolysis for 60 hours, electrolysis for 150 hours, to obtain the high-purity iron.

[0062] Example 3

[0063] This embodiment provides a method for preparing high-purity iron, the preparation method comprising:

[0064] Use pure water to dissolve analytical pure ferrous chloride, use analytical pure ammonia and hydrochloric acid to adjust the pH of the electrolyte to 2-4, and the concentration of ferrous ions in the electrolyte is 70g / L;

[0065] The electrolyte is subjected to first-stage precision filtration and second-stage precision filtration in sequence, the filtration accuracy of the first-stage precision filtration is 20μm, and the filtration accuracy of the second-stage precision filtration is 10μm;

[0066] Use 0.5 mol / L dilute sulfuric acid (prepared with analytical grade sulfuric acid and pure water) to soak the pure iron anode for 24 hours, and use pure water to clean the pure iron anode after acid immersion to remove the residual acid on the surface of the pure iron anode; use analytical grade dilute nitric acid to pickle the titanium plate cathode to remove oil stains and impurities;

[0067] Place the anode, cathode and electrolyte into a low-pressure electrolytic cell, maintain the vacuum degree at 1-100 Pa, and the current density at 100 A / m 2 , pre-electrolysis for 50 hours, electrolysis for 125 hours, to obtain the high-purity iron.

[0068] Example 4

[0069] This embodiment provides a method for preparing high-purity iron, the preparation method comprising:

[0070] Use pure water to dissolve analytical pure ferrous chloride, use analytical pure ammonia and hydrochloric acid to adjust the pH of the electrolyte to 2-4, and the concentration of ferrous ions in the electrolyte is 55g / L;

[0071] The electrolyte is subjected to first-stage precision filtration and second-stage precision filtration in sequence, the filtration accuracy of the first-stage precision filtration is 18μm, and the filtration accuracy of the second-stage precision filtration is 8μm;

[0072] The pure iron anode was soaked in 0.3 mol / L dilute sulfuric acid (prepared with analytical grade sulfuric acid and pure water) for 48 hours, and the pure iron anode after acid leaching was cleaned with pure water to remove the residual acid on the surface of the pure iron anode; the titanium plate cathode was pickled with analytical grade dilute nitric acid to remove oil stains and impurities;

[0073] Place the anode, cathode and electrolyte into a low-pressure electrolytic cell, maintain the vacuum degree at 1-100 Pa, and the current density at 80 A / m 2 , pre-electrolysis for 60 hours, electrolysis for 120 hours, to obtain the high-purity iron.

[0074] Comparative Example 1

[0075] Except that no fine filtration was performed, the other conditions in this comparative example were the same as those in Example 1.

[0076] Comparative Example 2

[0077] Except that the first stage fine filtration is not performed, the other conditions in this comparative example are the same as those in Example 1.

[0078] Comparative Example 3

[0079] Except that the second stage fine filtration is not performed, the other conditions of this comparative example are the same as those of Example 1.

[0080] Comparative Example 4

[0081] Except that the surface treatment of the electrolytic anode is not performed, the other conditions of this comparative example are the same as those of Example 1.

[0082] Comparative Example 5

[0083] In this comparative example, except that the surface treatment of the electrolytic cathode is not performed, the other conditions are the same as those of Example 1.

[0084] Comparative Example 6

[0085] Except that no pre-electrolysis was performed, the other conditions in this comparative example were the same as those in Example 1.

[0086] The electrolytic iron prepared in Examples 1-4 and Comparative Examples 1-6 was sampled and the purity was detected by glow discharge mass spectrometry (GDMS). The results are shown in Table 1.

[0087] Table 1

[0088] purity Example 1 4N Example 2 4N Example 3 5N Example 4 4N Comparative Example 1 2N Comparative Example 2 3N Comparative Example 3 3N Comparative Example 4 3N Comparative Example 5 3N Comparative Example 6 3N

[0089] It can be seen from the test results in Table 1 that the method for preparing high-purity iron provided by the present invention can prepare high-purity iron of 4N to 5N. Comparative Example 1 did not finely filter the electrolyte, and only 2N purity iron was obtained by electrolysis; while Comparative Examples 2 and 3 only performed one-stage fine filtration on the electrolyte, and 3N purity iron was obtained by electrolysis. Comparative Examples 4 and 5 did not perform surface treatment on the anode and cathode, and Comparative Example 6 did not perform pre-electrolysis, and only 3N purity iron was obtained by electrolysis.

[0090] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing high-purity iron, characterized in that: The preparation method comprises the following steps: Use pure water to dissolve analytical pure ferrous salt and adjust the pH to obtain an electrolyte; Performing at least two stages of precision filtration on the electrolyte; Surface treatment of electrolytic anodes and cathodes; The anode, cathode and electrolyte are used to carry out pre-electrolysis and electrolysis in sequence to obtain the high-purity iron.

2. The preparation method according to claim 1, characterized in that: The concentration of ferrous ions in the electrolyte is 50-70 g / L.

3. The preparation method according to claim 1, characterized in that: The pH of the electrolyte is adjusted to 2-4.

4. The preparation method according to claim 1, characterized in that: The precision filtration includes first-stage precision filtration and second-stage precision filtration performed sequentially.

5. The preparation method according to claim 1, characterized in that: The filtration accuracy of the first stage precision filtration is 15-20 μm, and the filtration accuracy of the second stage precision filtration is 5-10 μm.

6. The preparation method according to claim 1, characterized in that: The surface treatment of the electrolytic anode includes acid leaching and water washing performed in sequence; Surface treatment of electrolytic cathodes includes pickling.

7. The preparation method according to claim 1, characterized in that: The acid leaching includes immersing in dilute sulfuric acid with a concentration of 0.1 to 0.5 mol / L for not less than 24 hours.

8. The preparation method according to claim 1, characterized in that: The pre-electrolysis and electrolysis are carried out under the condition of a vacuum degree of 1-100Pa.

9. The preparation method according to claim 1, characterized in that: The current density of the pre-electrolysis and electrolysis is independently 50 to 100 A / m 2 .

10. The preparation method according to claim 1, characterized in that: The pre-electrolysis time is at least 48 hours.