Method for reducing iron and regulating vanadium enrichment phase by using iron ore concentrate

Abstract

The invention discloses a method for reducing iron and regulating and controlling a vanadium enrichment phase by using iron ore concentrate, and belongs to the technical field of mineral pre-enrichment. The method for reducing iron and regulating and controlling the vanadium enrichment phase by using the iron ore concentrate comprises the following steps: crushing an iron ore concentrate raw material, adding additive powder, uniformly mixing, and briquetting to obtain a roasting raw material; the roasting raw materials are placed in vacuum to be roasted, and reduced iron and a vanadium enrichment phase are obtained; wherein the additive powder comprises graphite powder, calcium oxide and magnesium oxide. According to the method, the pre-enrichment efficiency of vanadium is high, the vanadium extraction efficiency is improved by taking the vanadium enrichment phase as a raw material to extract vanadium, and the environmental protection requirement is met.

Description

Technical Field

[0001] This invention relates to the field of mineral pre-enrichment technology, and in particular to a method for reducing iron and controlling vanadium enrichment phases using iron concentrate. Background Technology

[0002] Iron concentrate is not only a major raw material for steel production, but its supply stability directly affects the quality and production cost of steel products, thereby impacting the competitiveness and market stability of the entire downstream industry chain. Vanadium, as an important associated element, significantly enhances the value of iron concentrate.

[0003] Vanadium metal has a wide range of applications, covering aerospace, chemistry, batteries, pigments, glass, optics, medicine and many other fields.

[0004] However, iron concentrate has a high iron content but low vanadium grade, is scattered, and has a complex occurrence state, making direct leaching of vanadium inefficient and environmentally unfriendly. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for reducing iron using iron concentrate and controlling the vanadium enrichment phase, aiming to solve the problems of low efficiency and environmental unfriendliness of directly leaching vanadium from iron concentrate.

[0006] To achieve the above objectives, this invention proposes a method for reducing iron and controlling the vanadium enrichment phase using iron concentrate, comprising the following steps: crushing iron concentrate raw material, adding additive powder, mixing evenly, and pressing into briquettes to obtain roasted raw material; placing the roasted raw material in a vacuum for roasting to obtain reduced iron and vanadium enriched phase; wherein the additive powder includes graphite powder, calcium oxide, and magnesium oxide.

[0007] In some embodiments, the crushing includes crushing and filtering the iron concentrate raw material to 100-300 mesh.

[0008] In some embodiments, the mass of the graphite powder is 1.3% to 12.90% of the mass of the iron concentrate raw material.

[0009] In some embodiments, the mass of the calcium oxide is 4.0% to 16.0% of the mass of the iron concentrate raw material.

[0010] In some embodiments, the mass of the magnesium oxide is 0.01% to 12% of the mass of the iron concentrate raw material.

[0011] In some embodiments, the pressure of the pressure block is 5MPa to 15MPa.

[0012] In some embodiments, the vacuum condition is: vacuum degree less than or equal to 10 Pa.

[0013] In some embodiments, the calcination temperature is 1000℃~1400℃, and the calcination heating rate is 5℃ / min~20℃ / min.

[0014] In some embodiments, after roasting, the material is kept warm for 1 to 3 hours.

[0015] In some embodiments, the calcination is carried out in a graphite crucible with a concave, arc-shaped bottom.

[0016] The beneficial effects of this invention are: The method provided by this invention for reducing iron and controlling the vanadium-enriched phase using iron concentrate fully utilizes the high content of iron oxides and titanium oxides. At high temperature, iron oxides are reduced to metallic iron by the combined action of graphite powder and calcium oxide. Calcium oxide and magnesium oxide are added to adjust the slag basicity, making it easier for vanadium oxides to combine with magnesium oxide to form the vanadium-enriched MgV₂O₅ phase. Compared with traditional methods, this method has the technical advantages of high vanadium enrichment efficiency, low environmental impact, high resource utilization efficiency, low production energy consumption, avoidance of large amounts of waste gas and wastewater, and high added value of the product. Attached Figure Description

[0017] Figure 1 This is an XRD (X-ray diffraction) pattern of a vanadium-enriched phase according to an embodiment of the present invention. The horizontal axis represents the diffraction angle, and the vertical axis represents the diffraction intensity. Figure 2 This is an XRD (X-ray diffraction) diagram of a pair of vanadium-enriched phases of the present invention, with the horizontal axis representing the diffraction angle and the vertical axis representing the diffraction intensity. Figure 3 This is a scanning electron microscope (SEM-EDS) mapping analysis diagram according to an embodiment of the present invention.

[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] To make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter recorded in the claims.

[0020] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0022] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0023] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0024] Iron ore concentrate, a crucial raw material for the steel industry, occupies a pivotal position in the modern industrial system. As the world's largest consumer of iron ore and steel producer, China has a huge demand for iron ore concentrate. Iron ore concentrate is not only a primary raw material for steel production, but its supply stability directly impacts the quality and production costs of steel products, thereby affecting the competitiveness and market stability of the entire downstream industrial chain. Vanadium, as an important by-product element, significantly enhances the value of iron ore concentrate.

[0025] However, iron concentrate has a high iron content but low vanadium grade, is scattered, and has a complex occurrence state, making direct leaching of vanadium inefficient and environmentally unfriendly.

[0026] In view of this, this application proposes a method for reducing iron and controlling the vanadium enrichment phase using iron concentrate, comprising the following steps: S1: Crush iron concentrate raw material, add additive powder, mix evenly, and then press into blocks to obtain roasting raw material; S2: The roasting raw material is placed in a vacuum and roasted to obtain a reduced iron and vanadium enriched phase; wherein the additive powder includes graphite powder, calcium oxide and magnesium oxide.

[0027] In a vacuum environment, graphite powder provides a carbon source, efficiently reducing iron oxides in iron concentrate to metallic iron. CaO and MgO adjust the slag basicity, allowing MgO to react with vanadium oxides at high temperatures to form stable vanadium-enriched phases such as MgV₂O₅. This selectively enriches and retains vanadium in the slag phase, effectively separating it from the reduced iron. Furthermore, CaO and MgO also possess desulfurization and dephosphorization capabilities, absorbing some harmful impurities such as sulfur and phosphorus in the iron concentrate and improving the purity of the reduced iron.

[0028] This method enables the reduction of iron and the enrichment and regulation of vanadium from iron concentrate to be completed in one step, efficiently recovering iron and associated valuable metal vanadium. This method has the technical advantages of high vanadium enrichment efficiency, low environmental pressure, high resource utilization efficiency, low production energy consumption, avoidance of large amounts of waste gas and wastewater, and high product added value.

[0029] In some embodiments, the pulverization includes pulverizing and filtering the iron concentrate raw material to 100-300 mesh. Fine particles of 100-300 mesh have a particle size of approximately 150-50 μm, significantly increasing the contact area between the iron concentrate and the additives. After being compressed into briquettes, the fine particles form a uniform microporous structure, ensuring a thorough reaction. After the reaction, a clear interface is generated, which is beneficial for further extraction of the vanadium-enriched phase. In some embodiments, the iron concentrate raw material is pulverized and filtered to any value within the 100-300 mesh range, such as 100 mesh, 150 mesh, 200 mesh, 250 mesh, or 300 mesh.

[0030] In some embodiments, the mass of the graphite powder is 1.3% to 12.90% of the mass of the iron concentrate raw material. In this embodiment, the mass of the graphite powder can control the degree of iron reduction and the separation of slag and iron after roasting, preferably 1.3% to 5%, and more preferably 4.8%.

[0031] In some embodiments, the mass of calcium oxide is 4.0% to 16.0% of the mass of the iron concentrate raw material. The addition of calcium oxide can adjust the alkalinity of the slag system to a suitable range, preferably 5.6% to 6.4%.

[0032] In some embodiments, the mass of magnesium oxide is 0.01% to 12% of the mass of the iron concentrate raw material. Magnesium oxide within this range helps to adjust alkalinity and reacts directly with vanadium, which facilitates the efficient enrichment of vanadium in a specific, easily processed slag phase. This significantly improves the grade of the vanadium-enriched phase, greatly simplifies the subsequent vanadium extraction process, and helps to increase the overall vanadium recovery rate. Preferably, it is 10.0% to 10.4%.

[0033] In some embodiments, the pressure of the briquette is 5 MPa to 15 MPa. After uniformly mixing the pulverized iron concentrate with the additive powder, the mixture is briquetteed under a pressure of 5 MPa to 15 MPa, resulting in a roasted raw material with suitable strength and porosity. Such briquetting ensures sufficient contact and reaction between the raw material and the additives during the roasting process.

[0034] In some embodiments, the vacuum condition is: a vacuum degree less than or equal to 10 Pa. Calcination under a vacuum condition of less than or equal to 10 Pa effectively reduces the partial pressure of gases during the calcination process. This is beneficial for the reduction reaction, reduces interference from impurity gases, suppresses possible oxidation side reactions, and improves the purity of the reduced iron and the quality of the vanadium-enriched phase. Simultaneously, the vacuum environment also helps remove volatile impurities, further purifying the reaction system and improving the quality of the final product. Furthermore, vacuum calcination can also reduce the amount of flue gas and dust emissions.

[0035] In some embodiments, the calcination temperature is 1000℃~1400℃, and the calcination heating rate is 5℃ / min~20℃ / min.

[0036] Within this temperature range, the reduction reaction can proceed fully, and iron can be effectively reduced to produce high-quality reduced iron. At the same time, vanadium can also undergo corresponding phase transformation and enrichment reactions at suitable temperatures to generate vanadium-enriched phases that are easy to separate and extract.

[0037] Controlling the heating rate during the roasting process to 5℃ / min~20℃ / min ensures a stable and uniform heating process. This avoids excessively rapid heating that could lead to large internal temperature gradients in the raw materials, causing localized overheating and material bursting, thus guaranteeing the uniformity and stability of the reaction. Simultaneously, an appropriate heating rate also facilitates the orderly progress of each reaction stage, allowing the reduction reaction and vanadium enrichment process to fully unfold, ensuring the quality and yield of the final product.

[0038] In some embodiments, after roasting, the material is kept warm for 1 to 3 hours.

[0039] By precisely controlling the additive ratio, calcination temperature, holding time, and vacuum degree, under synergistic effects, and without metallurgical operations, the final product can form two phases with significantly different physical morphology and chemical properties: metallic iron particles (reduced iron) and vanadium-rich slag phase (vanadium-enriched phase). This clear phase separation greatly facilitates subsequent crushing, magnetic separation, and vanadium extraction.

[0040] In some embodiments, the roasting is carried out in a graphite crucible with a concave, arc-shaped bottom. The concave bottom of the graphite crucible facilitates uniform heating of the pressed blocks, and the reduced metallic iron, due to its high density, settles at the bottom, making it easier to separate the metallic iron from the vanadium-rich slag phase after roasting.

[0041] Example 1

[0042] (1) The iron concentrate is crushed and filtered to 200 mesh, and then mixed evenly with 4.8 wt% graphite powder, 6.0 wt% calcium oxide and 10.0 wt% magnesium oxide in a mortar and then pressed into briquettes under a pressure of 15 MPa. (2) The compressed material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to <10Pa. The temperature was increased to 1300℃ at 10℃ / min and held for 2h to obtain the reduced iron and vanadium enriched phase.

[0043] Example 2 (1) The iron concentrate is crushed and filtered to 200 mesh, and then mixed evenly with 4.8 wt% graphite powder, 5.6 wt% calcium oxide and 10.4 wt% magnesium oxide in a mortar and then pressed into briquettes under a pressure of 15 MPa. (2) The compressed material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to <10Pa. The temperature was increased to 1300℃ at 10℃ / min and held for 2h to obtain the reduced iron and vanadium enriched phase.

[0044] Example 3 (1) The iron concentrate is crushed and filtered to 200 mesh, and then mixed evenly with 4.8 wt% graphite powder, 6.4 wt% calcium oxide and 10.4 wt% magnesium oxide in a mortar and then pressed into briquettes under a pressure of 15 MPa. (2) The compressed material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to <10Pa. The temperature was increased to 1300℃ at 10℃ / min and held for 2h to obtain the reduced iron and vanadium enriched phase.

[0045] Example 4 (1) The iron concentrate is crushed and filtered to 150 mesh, and then mixed evenly with 4.8 wt% graphite powder, 8.0 wt% calcium oxide and 8.0 wt% magnesium oxide in a mortar and then pressed into briquettes under a pressure of 10 MPa. (2) The compressed material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to <10Pa. The temperature was increased to 1300℃ at 15℃ / min and held for 2.5h to obtain the reduced iron and vanadium enriched phase.

[0046] Example 5 (1) The iron concentrate is crushed and filtered to 300 mesh, and then mixed evenly with 4.8 wt% graphite powder, 4.8 wt% calcium oxide and 11.2 wt% magnesium oxide in a mortar and then pressed into briquettes under a pressure of 10 MPa. (2) The compressed material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to <10Pa. The temperature was increased to 1300℃ at 15℃ / min and held for 2.5h to obtain the reduced iron and vanadium enriched phase.

[0047] Comparative Example 1: (1) The vanadium-containing low-grade iron concentrate is crushed and filtered to 200 mesh, and then mixed evenly with 4.8wt% graphite powder and 16.0wt% calcium oxide in a mortar and briquette under a pressure of 15 MPa.

[0048] (2) The briquetted material was placed in the graphite crucible used in the experiment. The crucible was placed in a vertical vacuum furnace and evacuated to 0-10 Pa. The temperature was increased to 1300℃ at 10℃ / min and held for 2 hours to obtain reduced iron and slag phase.

[0049] Performance testing The contents of various elements in the iron concentrate were determined, and the results are shown in Table 1: Table 1. Element content in iron concentrate

[0050] Furthermore, the vanadium-enriched phase / slag phase in the examples and comparative examples were characterized by XRD and SEM-EDS, and the yield of reduced iron was calculated: The XRD testing method includes the following steps: After grinding and filtering the slag sample containing vanadium enriched phase to 200 mesh, X-ray diffraction (XRD, X'pert 3 powder, Malvern Panalytical, Netherlands) is used to measure the sample under Cu Kα radiation, with a scanning range of 10° to 90° and a step size of 0.02626° to identify the crystalline phase in the sample.

[0051] The SEM-EDS testing method includes the following steps: A vanadium-enriched slag sample is loaded into epoxy resin. Using SiC paper, the sample is polished from coarse to fine, and its microstructure and the presence of scratches are carefully observed using an optical microscope (OM). Samples without scratches are then used for scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS, VEGA3, Tescan, Czech Republic) in backscattered electron mode using an accelerating voltage of 20 kV to study the morphology and chemical composition of the phases within the sample. To improve the accuracy of the composition measurement, the composition of each phase is measured three times.

[0052] The test results are shown in Table 2.

[0053] Table 2. Yield of reduced iron in the examples and comparative examples

[0054] See the instruction manual appendix Figure 1 and 3 The results are from Example 1. According to X-ray diffraction (XRD) analysis, vanadium in the sample is mainly found in the MgV₂O₅ phase, indicating that vanadium combines with magnesium during calcination to form stable vanadate compounds. Energy dispersive spectroscopy (SEM-EDS) mapping analysis shows a highly consistent distribution of magnesium, vanadium, and titanium in the sample, indicating that these three elements exhibit similar migration and enrichment behaviors during calcination. Combining the XRD and SEM-EDS analysis results, it is evident that vanadium tends to enrich in the MgTi₂O₅ phase during calcination and solidifies within MgTi₂O₅ to form the MgV₂O₅ phase.

[0055] See the instruction manual appendix Figure 2 Table 2 shows the test results of Comparative Example 1. The reduced iron yield of Comparative Example 1 is much higher than that of the Example. However, X-ray diffraction and scanning electron microscopy revealed that no obvious vanadium-rich phase was generated during the roasting process, indicating that simply adding graphite powder and calcium oxide failed to achieve the effect of enriching vanadium while reducing iron in iron concentrate.

[0056] In summary, the method for reducing iron and controlling the vanadium-enriched phase using iron concentrate provided by this invention fully utilizes the high content of iron oxides and titanium oxides. At high temperatures, iron oxides are reduced to metallic iron by the combined action of graphite powder and calcium oxide. The addition of calcium oxide and magnesium oxide adjusts the slag basicity, making it easier for vanadium oxides to combine with magnesium oxide to form the vanadium-enriched MgV₂O₅ phase. Compared with traditional methods, this method has the technical advantages of high vanadium enrichment efficiency, low environmental impact, high resource utilization efficiency, low production energy consumption, avoidance of large amounts of waste gas and wastewater, and high product added value.

[0057] Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0058] The above description is only a part or preferred embodiment of the present invention. Neither the text nor the drawings should limit the scope of protection of the present invention. All equivalent structural transformations made using the content of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A method for reducing iron and controlling the vanadium enrichment phase using iron concentrate, characterized in that, Includes the following steps: The iron concentrate raw material is crushed, and the additive powder is added, mixed evenly, and then pressed into briquettes to obtain the roasting raw material. The roasting raw material was placed in a vacuum and roasted to obtain a reduced iron and vanadium-enriched phase. The additive powder includes graphite powder, calcium oxide, and magnesium oxide.

2. The method for reducing iron and controlling the vanadium enrichment phase using iron concentrate according to claim 1, characterized in that, The crushing process includes crushing and filtering the iron concentrate raw material to 100-300 mesh.

3. The method for reducing iron and controlling the vanadium enrichment phase using iron concentrate according to claim 2, characterized in that, The mass of the graphite powder is 1.3% to 12.90% of the mass of the iron concentrate raw material.

4. The method for reducing iron and controlling the vanadium enrichment phase using iron concentrate according to claim 3, characterized in that, The mass of the calcium oxide is 4.0% to 16.0% of the mass of the iron concentrate raw material.

5. The method for reducing iron and controlling the vanadium enrichment phase using iron concentrate according to claim 4, characterized in that, The mass of the magnesium oxide is 0.01% to 12% of the mass of the iron concentrate raw material.

6. The method for reducing iron with iron concentrate and controlling the vanadium enrichment phase according to any one of claims 1 to 5, characterized in that, The pressure of the pressure block is 5MPa~15MPa.

7. The method for reducing iron with iron concentrate and controlling the vanadium enrichment phase according to any one of claims 1 to 5, characterized in that, The vacuum condition is: vacuum degree less than or equal to 10 Pa.

8. The method for reducing iron with iron concentrate and controlling the vanadium enrichment phase according to any one of claims 1 to 5, characterized in that, The calcination temperature is 1000℃~1400℃, and the calcination heating rate is 5℃ / min~20℃ / min.

9. The method for reducing iron with iron concentrate and controlling the vanadium enrichment phase according to any one of claims 1 to 5, characterized in that, After roasting, the food is kept warm for 1 to 3 hours.

10. The method for reducing iron and controlling the vanadium enrichment phase using iron concentrate according to claim 1, characterized in that, The calcination is carried out in a graphite crucible with a concave, arc-shaped bottom.

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