Method for preparing metallic iron through ultrasonic-assisted leaching-electrolysis of iron ore powder

Abstract

The invention discloses a method for preparing metallic iron from iron ore powder through ultrasonic-assisted leaching-electrolysis, which comprises the following steps: (1) crushing and finely grinding iron ore into iron ore powder, then carrying out sulfuric acid leaching under the ultrasonic-assisted action, and filtering to obtain an iron leachate; (2) reducing Fe < 3 + > in the iron leaching solution into Fe < 2 + > to obtain an iron reduction solution; (3) removing impurities from the iron reduction liquid, and electrolyzing the iron reduction liquid as electrolyte under the action of direct current; and (4) after electrolysis is finished, cleaning and drying the cathode material to obtain metal iron. Electrolysis after auxiliary leaching of the iron ore powder is conducted through the heat effect, the cavitation effect and the chemical effect generated by ultrasonic waves, the iron leaching rate is increased, then the follow-up current efficiency is improved, the method has the advantages of being small in environmental pollution, low in energy consumption, high in current efficiency and the like, and the problems of carbon emission, high cost and the like in the current metal iron preparation process are solved.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy, and in particular relates to a method for preparing metallic iron by ultrasonically assisted leaching-electrolysis of iron ore powder. Background Art

[0002] Iron is a key basic raw material for the preparation of steel and advanced materials. With the development of science and technology, human demand for iron-based materials is increasing. The traditional blast furnace method is still the mainstream ironmaking process. It uses coke obtained from coking of non-renewable resources such as coal as fuel and reducing agent to reduce iron ore. It has shortcomings such as high energy consumption, large carbon emissions, and environmental pollution.

[0003] To reduce CO2 emissions from the steel industry, it is crucial to develop efficient, low-carbon ironmaking processes. Currently, the main methods are hydrogen-based reduction and aqueous electrolysis, both of which use zero-carbon input without using carbon as a reducing agent. Hydrogen-based reduction ironmaking uses hydrogen instead of coke as a reducing agent to reduce iron ore. Hydrogen is generated by electricity generated from renewable energy and then electrolyzed into water. This process produces no CO2, but it requires high iron ore grade, high hydrogen production costs, and difficulty storing and transporting hydrogen. Aqueous electrolysis, which reduces iron ions to metallic iron at the cathode, is an important approach to achieving low-carbon, green steel production, offering advantages such as low carbon emissions, low costs, and high product purity.

[0004] Patent CN 113481540 A discloses a method for producing high-purity iron by electrolysis. Using a soluble anode such as industrial pure iron or low-carbon steel on a prefabricated cathode, electrolysis is performed in an acidic electrolyte primarily containing FeSO4·7H2O to produce iron with a purity of 99.90% to 99.99%. This method is simple and produces high-purity electrolytic iron. However, the use of soluble anodes such as industrial pure iron or low-carbon steel limits the availability of electrode materials, and the use of acid-resistant separator materials is expensive, increasing raw material costs. Summary of the Invention

[0005] The present invention provides a method for preparing metallic iron by ultrasonically assisted leaching-electrolysis of iron ore powder. The purpose is to address the technical difficulties of the current mainstream pyrometallurgical blast furnace ironmaking, such as high energy consumption and serious environmental pollution, and the high cost of zero-carbon input hydrogen metallurgy ironmaking. By adopting ultrasonically assisted leaching-electrolysis of iron ore powder to prepare metallic iron, the method has the advantages of low environmental pollution, low energy consumption and high iron purity of the product.

[0006] The technical solution of the present invention:

[0007] A method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder comprises the following steps:

[0008] (1) crushing and finely grinding the iron ore to produce iron ore powder, then leaching it with sulfuric acid under the assistance of ultrasound, and filtering to obtain an iron leachate;

[0009] (2) Fe in the iron leaching solution 3+ Reduction to Fe 2+ , obtaining an iron-reducing solution;

[0010] (3) removing impurities from the iron reduction solution, and then using the removed impurities as an electrolyte for electrolysis under the action of direct current;

[0011] (4) After the electrolysis reaction is completed, the cathode material is cleaned and dried to obtain metallic iron.

[0012] Preferably, the iron ore powder in step (1) has a particle size of less than 74 μm, accounting for 80% or more.

[0013] Preferably, in the ultrasonic-assisted action in step (1), the ultrasonic frequency is 20-60 kHz, the ultrasonic power is 500 W-1000 W, the leaching liquid-solid ratio is 2.5-6:1, the sulfuric acid concentration is 1.5-3.0 mol / L, the leaching temperature is 40-90°C, the stirring rate is 200-600 rpm, and the leaching time is 2-5 h.

[0014] Preferably, the iron content in the iron leaching solution in step (1) is 108-194 g / L; the iron leaching rate is 70-94%.

[0015] Preferably, the Fe of the iron leaching solution in step (2) 3+ Reduction to Fe 2+ The method is achieved by adding iron chips, wherein the amount of the iron chips added is in a mass ratio of 0.5 to 1.5 to the amount of iron in the iron ore powder.

[0016] Preferably, in step (3), the iron reduction solution is removed from impurities by adding sulfides, and the amount of sulfides added depends on the type and content of impurities; the sulfides include sodium sulfide and hydrogen sulfide; and the impurities include: Cu, Co, Ni, Ca and Mg ions.

[0017] Preferably, the cathode material of the electrolysis process in step (3) is titanium alloy, and the anode material is nickel alloy. The cathode reaction is: Fe 2+ +2e→Fe; The anode reaction is: The overall reaction is:

[0018]

[0019] Preferably, in step (3), the pH of the electrolyte is adjusted to 1.5-3.5 by sulfuric acid solution before electrolysis; during the electrolysis process, the current density is 600-800 A / m2, the electrolytic cell voltage is 3-3.5 V, the electrolysis temperature is 25-40°C, and the electrolysis time is 2-6 h.

[0020] Preferably, a small amount of L-ascorbic acid is added during the electrolysis process, with the concentration of ascorbic acid being 0.05 to 0.3 mol / L, to maintain the stability of the electrolyte.

[0021] Preferably, the cathode material in step (4) is first rinsed with distilled water, the distilled water after rinsing is poured out, and then the cathode material is placed in distilled water and cleaned with ultrasonic waves;

[0022] The ultrasonic frequency is 20-60 kHz, the ultrasonic power is 500W-1000W, the ultrasonic temperature is 40-90°C, and the stirring rate is 200-600 rpm;

[0023] The drying process has a drying temperature of 100 to 180° C. and a drying time of 1 to 2 hours.

[0024] The iron purity of the obtained metallic iron product is greater than 96%, and the current efficiency is greater than 92%.

[0025] The present invention has the following advantages and positive effects:

[0026] (1) The present invention prepares metallic iron through ultrasonic-assisted leaching-electrolysis. Compared with the high CO2 emissions and high-temperature process conditions of 1250-1300°C in traditional pelletizing-blast furnace ironmaking, it has the advantages of less environmental pollution and low energy consumption, and solves the current problems of carbon emissions and high costs in the metallic iron preparation process.

[0027] (2) The present invention arranges an ultrasonic generator during the leaching process of iron ore powder, and utilizes the thermal effect, cavitation effect and chemical effect generated by ultrasound to assist the leaching of iron ions, thereby greatly accelerating the H + The mass transfer effect inside the iron ore powder particles increases the iron leaching rate and thus improves the subsequent current efficiency.

[0028] (3) The present invention adds iron filings to remove the Fe 3+ Reduction to Fe 2+ , and then use sulfide to purify and remove impurities, preventing Fe 3+ The iron loss caused by hydrolysis and the influence of impurities on the subsequent electrolysis efficiency are reduced, and the reagents used are easily available and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below through specific examples and in conjunction with the accompanying drawings.

[0031] Example 1:

[0032] The iron ore used comes from Peru, and its main components and their mass percentages are FeO: 28.54%, Al2O3: 0.28%, V2O3: 0.09%, SiO2: 1.39%, CaO: 0.54%, MgO: 0.92%, CuO: 0.27%, Co2O3: 0.19%, NiO2: 0.20%, TiO2: 0.21%, and TFe: 65.35%.

[0033] Process such as Figure 1 As shown:

[0034] (1) The iron ore was crushed and finely ground into iron ore powder with a particle size of less than 74 μm accounting for 80%, and then leached under the auxiliary action of ultrasonic frequency of 20 kHz and power of 800 W; wherein the leaching liquid-solid ratio was 2.5:1, the sulfuric acid concentration was 2.0 mol / L, the leaching temperature was 90°C, the stirring rate was 400 rpm, the leaching time was 3 h, and the iron leachate was filtered to obtain the iron content of 194 g / L and the iron leaching rate was 70%;

[0035] (2) Add iron filings with a mass ratio of 1.0 to iron ore powder to reduce the Fe content in the iron leaching solution. 3+ Reduction to Fe 2+ , obtaining an iron-reducing solution;

[0036] (3) Sodium sulfide is added to remove impurities in the iron reduction solution, including Ca, Mg, Cu, Co, Ni and other ions; then the pH is adjusted to 3.5 with sulfuric acid solution as the electrolyte and electrolysis is carried out under the action of direct current; the current density is 800A / m 2 , the electrolytic cell voltage was 3 V, the electrolysis temperature was 40°C, and the electrolysis time was 4 h; 0.05 mol / L L-ascorbic acid was added during the electrolysis process to maintain the stability of the electrolyte.

[0037] (4) After the electrolysis reaction is completed, the cathode material is first washed with distilled water, the water is poured out, and then it is placed in distilled water and cleaned with ultrasonic waves, and then dried at a temperature of 180°C for 1.5 hours to obtain metallic iron.

[0038] The purity of the obtained metallic iron was 98%, and the current efficiency was 94%.

[0039] Comparative Example 1:

[0040] A comparative test was conducted without ultrasonic treatment under the same conditions as in Example 1. The purity of the obtained iron was 87% and the current efficiency was 84%.

[0041] Example 2:

[0042] The iron ore used comes from Peru, and its main components and their mass percentages are FeO: 28.54%, Al2O3: 0.28%, V2O3: 0.09%, SiO2: 1.39%, CaO: 0.54%, MgO: 0.92%, CuO: 0.27%, Co2O3: 0.19%, NiO2: 0.20%, TiO2: 0.21%, and TFe: 65.35%.

[0043] Process such as Figure 1 As shown:

[0044] (1) Iron ore powder was leached with the aid of an ultrasonic wave at a frequency of 60 kHz and an ultrasonic power of 500 W; wherein the leaching liquid-solid ratio was 6:1, the sulfuric acid concentration was 3.0 mol / L, the leaching temperature was 40°C, the stirring rate was 600 rpm, the leaching time was 2 h, and the iron leachate was obtained by filtration; wherein the iron content was 108 g / L and the iron leaching rate was 94%;

[0045] (2) Add iron filings with a mass ratio of 0.5 to iron ore powder to reduce the Fe content in the iron leaching solution. 3+ Reduction to Fe 2+ , obtaining an iron-reducing solution;

[0046] (3) Add hydrogen sulfide to remove impurities in the iron reduction solution, including Ca, Mg, Cu, Co, Ni ions, etc.; then adjust the pH to 2.0 with sulfuric acid solution as the electrolyte and perform electrolysis under the action of direct current; the current density is 600A / m 2 , the electrolytic cell voltage was 3.5 V, the electrolysis temperature was 25°C, and the electrolysis time was 2 h; 0.1 mol / L L-ascorbic acid was added during the electrolysis process to maintain the stability of the electrolyte.

[0047] (4) After the electrolysis reaction is completed, the cathode material is first washed with distilled water, and then the water is poured out and the cathode material is placed in distilled water and cleaned with ultrasonic waves. After the cathode material is cleaned, it is dried at a temperature of 130°C for 2 hours to obtain metallic iron.

[0048] The purity of the obtained metallic iron was 96%, and the current efficiency was 92%.

[0049] Comparative Example 2:

[0050] A comparative test was conducted under the same conditions as in Example 2 without ultrasonic treatment. The purity of the obtained iron was 85% and the current efficiency was 82%.

[0051] Example 3:

[0052] The iron ore used comes from Peru, and its main components and their mass percentages are FeO: 28.54%, Al2O3: 0.28%, V2O3: 0.09%, SiO2: 1.39%, CaO: 0.54%, MgO: 0.92%, CuO: 0.27%, Co2O3: 0.19%, NiO2: 0.20%, TiO2: 0.21%, and TFe: 65.35%.

[0053] Process such as Figure 1 As shown:

[0054] (1) Iron ore powder was leached with the aid of an ultrasonic wave having a frequency of 40 kHz and an ultrasonic power of 1000 W; wherein the leaching liquid-solid ratio was 5:1, the sulfuric acid concentration was 1.5 mol / L, the leaching temperature was 60°C, the stirring rate was 200 rpm, the leaching time was 5 h, and the iron leachate was obtained by filtration; wherein the iron content was 117 g / L and the iron leaching rate was 85%;

[0055] (2) Add iron filings with a mass ratio of 1.5 to iron ore powder to reduce the Fe content in the iron leaching solution. 3+ Reduction to Fe 2+ , obtaining an iron-reducing solution;

[0056] (3) Add hydrogen sulfide to remove impurities in the iron reduction solution, including Ca, Mg, Cu, Co, Ni ions, etc.; then adjust the pH to 1.5 with sulfuric acid solution as the electrolyte and perform electrolysis under the action of direct current; the current density is 700A / m 2 , the electrolytic cell voltage was 3.2 V, the electrolysis temperature was 35°C, and the electrolysis time was 6 h; 0.3 mol / L L-ascorbic acid was added during the electrolysis process to maintain the stability of the electrolyte.

[0057] (4) After the electrolysis reaction is completed, the cathode material is first washed with distilled water, and then the water is poured out and the cathode material is placed in distilled water and cleaned with ultrasonic waves. After the cathode material is washed, it is dried at a temperature of 100°C for 1 hour to obtain metallic iron.

[0058] The purity of the obtained metallic iron was 97%, and the current efficiency was 93%.

[0059] Comparative Example 3:

[0060] A comparative test was conducted under the same conditions as in Example 3 without ultrasonic treatment. The purity of the obtained iron was 86% and the current efficiency was 83%.

[0061] Comparative Example 4:

[0062] No hydrogen sulfide was added to remove impurities in the iron reduction solution. A comparative test was conducted under the same conditions as in Example 3. The purity of the obtained iron was 72% and the current efficiency was 68%.

[0063] Comparative Example 5:

[0064] No L-ascorbic acid was added during the electrolysis process. A comparative test was conducted under the same conditions as in Example 3. The purity of the obtained iron was 78%, and the current efficiency was 75%.

[0065] Comparative Example 6:

[0066] Without the process of adding iron filings in step (2), a comparative test was conducted under the same conditions as in Example 3. The purity of the obtained iron was 70%, and the current efficiency was 43%.

[0067] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder, characterized in that: The following steps are involved: (1) The iron ore is crushed and finely ground into iron ore powder, and then sulfuric acid leaching is performed under the assistance of ultrasound, and the iron leachate is obtained by filtration; (2) Fe in the iron leaching solution 3+ Reduction to Fe 2+ , obtaining an iron-reducing solution; (3) removing impurities from the iron reduction solution, and then using it as an electrolyte for electrolysis under the action of direct current; (4) After the electrolysis reaction is completed, the cathode material is cleaned and dried to obtain metallic iron.

2. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: The iron ore powder in step (1) has a particle size of less than 74 μm, accounting for 80% or more.

3. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: In the ultrasonic-assisted effect described in step (1), the ultrasonic frequency is 20~60kHz, the ultrasonic power is 500W~1000W, the leaching liquid-solid ratio is 2.5~6:1, the sulfuric acid concentration is 1.5~3.0mol / L, the leaching temperature is 40~90℃, the stirring rate is 200~600rpm, and the leaching time is 2~5h.

4. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: The iron content in the iron leaching solution in step (1) is 108-194 g / L; the iron leaching rate is 70-94%.

5. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: Fe of the iron leaching solution in step (2) 3+ Reduction to Fe 2+ This is achieved by adding iron filings, wherein the amount of the iron filings added is in a mass ratio of 0.5 to 1.5 to the amount of iron in the iron ore powder.

6. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: In the step (3), the iron reduction solution is removed from impurities by adding sulfides; the sulfides include sodium sulfide and hydrogen sulfide; and the impurities include Cu, Co, Ni, Ca and Mg ions.

7. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: In the electrolysis process in step (3), the cathode material is titanium alloy and the anode material is nickel alloy.

8. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: In the step (3), the pH of the electrolyte is adjusted to 1.5-3.5 by sulfuric acid solution before electrolysis; the current density during the electrolysis is 600-800 A / m 2 , the electrolytic cell voltage is 3~3.5V, the electrolysis temperature is 25~40℃, and the electrolysis time is 2~6h.

9. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 8, characterized in that: L-ascorbic acid is added during the electrolysis process, and the concentration of the ascorbic acid is 0.05-0.3 mol / L.

10. The method for preparing metallic iron by ultrasonic-assisted leaching-electrolysis of iron ore powder according to claim 1, characterized in that: In step (4), the cathode material is first rinsed with distilled water, the distilled water is discarded, and then the cathode material is placed in the distilled water and cleaned with ultrasonic waves; The ultrasonic frequency is 20~60kHz, the ultrasonic power is 500W~1000W, the ultrasonic temperature is 40~90℃, and the stirring rate is 200~600rpm; The drying process has a drying temperature of 100 to 180° C. and a drying time of 1 to 2 hours.

Images