Method for recovering iron, vanadium and titanium from slag

Abstract

This invention discloses a method for recovering iron, vanadium, and titanium from furnace slag, comprising the following sequential steps: S1, adding hot titanium-containing furnace slag, vanadium-containing tailings, and iron raw materials into an electric furnace and heating at 1300–1500°C for a predetermined time; wherein the titanium-containing furnace slag is a byproduct obtained from vanadium-titanium magnetite ironmaking in a blast furnace or non-blast furnace, the vanadium-containing tailings are the tailings remaining after vanadium removal from titanium tetrachloride, and the iron raw materials are ferrous oxide, ferric oxide, and / or iron; S2, adding a carbonaceous reducing agent to the electric furnace and performing reduction carbonization at 1500–1750°C; S3, discharging the slag and performing post-processing to obtain titanium carbide slag and ferrovanadium products. This invention can recover vanadium, titanium, and iron resources from titanium-containing furnace slag and vanadium-containing tailings, and can also reduce the iron content in titanium carbide slag, ensuring the product quality and stable operation of the entire process.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method for recovering iron, vanadium, and titanium from furnace slag. Background Technology

[0002] The Panxi region is rich in vanadium-titanium magnetite resources, with titanium reserves accounting for over 90% of the national total. However, this mine is a typical polymetallic associated mineral resource of iron, vanadium, and titanium. While developing and utilizing iron, half of the titanium resources are enriched in the slag (with a TiO2 content as high as 15-45 wt%) after iron concentrate is smelted in blast furnaces or non-blast furnaces. The stockpiling of this titanium-containing slag not only causes environmental problems but also results in a significant waste of resources (currently, the utilization rate of titanium resources in the Panxi region is only 28%).

[0003] TiO2 in this type of titanium-containing slag can be converted into TiC by carbothermal reduction at high temperature, and then further chlorinated at low temperature to prepare titanium tetrachloride, thereby realizing the recycling of titanium resources in this type of slag. This is also the only titanium extraction technology route that has achieved industrial application at present.

[0004] Because slag and iron cannot be completely separated during the ironmaking process, this type of titanium-containing slag often contains 1 to 8 wt% iron. In the further carbothermic reduction and low-temperature chlorination titanium extraction process, this part of the Fe will react with chlorine to generate ferric chloride. Ferric chloride entering titanium tetrachloride will not only affect the product quality, but also cause blockage of the chlorination system and affect the stable operation of the process. Therefore, it is necessary to control the iron content in this type of slag to a low level before chlorination.

[0005] On the other hand, since the Panzhihua vanadium-titanium magnetite is a co-existing mineral resource, the slag in this type of furnace also contains a certain amount of vanadium. The crude titanium tetrachloride obtained after high-temperature carbothermal reduction and low-temperature chlorination has a high vanadium content and must be removed through a refining process; otherwise, it will affect the subsequent production of sponge titanium and titanium dioxide. After vanadium removal in titanium tetrachloride refining, vanadium is enriched in the refining tailings. This vanadium-containing tailings contains approximately 10–20 wt% vanadium and 12–25 wt% titanium. Its stockpiling not only causes environmental pollution but also wastes vanadium and titanium resources. Summary of the Invention

[0006] The main objective of this invention is to provide a method to solve the technical problem of how to extract iron, vanadium, and titanium from titanium-containing slag and vanadium-containing tailings.

[0007] According to one aspect of the present invention, a method for recovering iron, vanadium, and titanium from slag is provided, comprising the following steps performed sequentially:

[0008] S1, hot titanium-containing slag, vanadium-containing tailings and iron raw materials are added to an electric furnace and heated at 1300-1500℃ for a predetermined time; wherein the titanium-containing slag is a by-product obtained from vanadium-titanium magnetite after ironmaking in a blast furnace or non-blast furnace, the vanadium-containing tailings is the tailings remaining after vanadium removal by titanium tetrachloride refining, and the iron raw materials are ferrous oxide, ferric oxide and / or iron.

[0009] S2, add carbonaceous reducing agent into electric furnace and carry out reduction carbonization at 1500-1750℃;

[0010] S3, after slag discharge and post-processing, yields titanium carbide slag and ferrovanadium products.

[0011] According to one embodiment of the present invention, the titanium-containing slag comprises, by mass percentage: 9-25% Ti, 1-10% Fe, 3-12% Mg, 2-20% Ca, 7-14% Si, 6-8% Al and 0.1-1% TV.

[0012] According to one embodiment of the present invention, the vanadium-containing tailings comprises, by mass percentage: 10-20% TV, 12-25% Ti, 2-5% Cl, 4-7% Si, 1-6% Fe, 2-4% Al, 5-10% Ca, and 1-3% Mg.

[0013] According to one embodiment of the present invention, in step S1, the predetermined time is 20 to 50 minutes.

[0014] According to one embodiment of the present invention, in step S1, based on 100 parts by weight of titanium-containing slag, the amounts of vanadium-containing tailings and iron raw materials added are 5 to 40 parts by weight and 1 to 5 parts by weight, respectively.

[0015] According to one embodiment of the present invention, with the amount of titanium-containing slag added in step S1 being 100 parts by weight, the amount of carbonaceous reducing agent added in step S2 is 10 to 30 parts by weight.

[0016] According to one embodiment of the present invention, in step S2, the reduction carbonization time is 1 to 6 hours.

[0017] According to one embodiment of the present invention, in step S2, the carbonaceous reducing agent is at least one of anthracite, coke, petroleum coke and graphite, and wherein the fixed carbon content is not less than 75%; and / or the particle size of the carbonaceous reducing agent is not greater than 3 mm.

[0018] According to one embodiment of the present invention, in step S3, the post-processing includes: sequentially performing cooling, crushing, and magnetic separation.

[0019] According to one embodiment of the present invention, in step S3, the particle size is crushed to less than 80 mesh, preferably between 100 and 240 mesh; and / or when performing magnetic separation, the magnetic field strength is controlled to be 500 to 3000 Gs, preferably 500 to 1500 Gs.

[0020] In the technical solution of this invention, titanium-containing slag, vanadium-containing tailings, and iron raw materials are first heated at 1300–1500°C for a predetermined time. Then, a carbonaceous reducing agent is added, and reduction carbonization is carried out at 1500–1750°C. On the one hand, the titanium in the titanium-containing slag and vanadium-containing tailings can be converted into titanium carbide that can be chlorinated at low temperatures, thus extracting titanium resources from the slag. On the other hand, the iron and vanadium in the titanium-containing slag and vanadium-containing tailings combine to form ferrovanadium alloy, which is more easily separated from the titanium carbide slag after enrichment and growth. This invention can both recover vanadium and titanium resources from titanium-containing slag and vanadium-containing tailings and reduce the iron content in titanium carbide slag, ensuring the product quality and stable operation of the entire process. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0022] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0023] As mentioned in the background section above, the inventors of this application recognized that the titanium-containing slag obtained from vanadium-titanium magnetite after ironmaking in a blast furnace or non-blast furnace contains 1-8% iron. This iron content can affect the subsequent low-temperature chlorination process, therefore it is necessary to control the iron content in the slag to a low level before chlorination. The inventors further recognized that the vanadium-containing tailings obtained after vanadium removal from titanium tetrachloride contain approximately 10-20% vanadium and approximately 12-25% titanium, resulting in a waste of vanadium and titanium resources. Based on the above understanding, this invention proposes one or more embodiments as described below to achieve the extraction and recovery of iron, vanadium, and titanium from titanium-containing slag and vanadium-containing tailings, and to reduce the iron content in titanium carbide slag used for low-temperature chlorination.

[0024] This invention proposes a method for recovering iron, vanadium, and titanium from furnace slag, comprising the following steps performed sequentially:

[0025] S1, hot titanium-containing slag, vanadium-containing tailings and iron raw materials are added to an electric furnace and heated at 1300-1500℃ for a predetermined time; wherein the titanium-containing slag is a by-product obtained from vanadium-titanium magnetite after ironmaking in a blast furnace or non-blast furnace, the vanadium-containing tailings is the tailings remaining after vanadium removal from titanium tetrachloride, and the iron raw materials are ferrous oxide, iron oxide and / or iron;

[0026] S2, add carbonaceous reducing agent into electric furnace and carry out reduction carbonization at 1500-1750℃;

[0027] S3, after slag discharge and post-processing, yields titanium carbide slag and ferrovanadium products.

[0028] In an embodiment of the present invention, titanium-containing slag, vanadium-containing tailings, and iron raw materials are first heated at 1300–1500°C for a predetermined time. Then, a carbonaceous reducing agent is added, and reduction carbonization is carried out at 1500–1750°C. On the one hand, the titanium in the titanium-containing slag and vanadium-containing tailings can be converted into titanium carbide that can be chlorinated at low temperatures, thus extracting titanium resources from the slag. On the other hand, the iron and vanadium in the titanium-containing slag and vanadium-containing tailings combine to form ferrovanadium alloy, which is more easily separated from the titanium carbide slag after enrichment and growth. The present invention can both recover vanadium and titanium resources from titanium-containing slag and vanadium-containing tailings and reduce the iron content in titanium carbide slag (for example, the iron content in titanium carbide slag can be reduced to below 1 wt%), ensuring the product quality and stable operation of the entire process.

[0029] In the technical solution of this invention, titanium-containing slag is prepared into titanium carbide slag through high-temperature carbonization and reduction. The titanium carbide slag can then be further processed into titanium tetrachloride through low-temperature chlorination. During the carbonization and reduction process, a certain amount of vanadium-containing tailings is added, allowing the iron in the titanium-containing slag to combine with the vanadium in the vanadium-containing tailings to form a ferrovanadium alloy. This method can both recover vanadium resources from the vanadium-containing tailings and reduce the iron content in the titanium carbide slag.

[0030] The heating at 1300–1500℃ in step S1 serves two purposes: firstly, it raises the temperature to facilitate the subsequent carbonization and reduction reaction; secondly, it removes the small amount of chloride ions from the vanadium-containing tailings. The addition of iron raw materials (ferrous oxide, ferric oxide, and / or iron) in step S1 serves two purposes: firstly, it provides iron to combine with vanadium in the vanadium-containing tailings to produce ferrovanadium alloy; secondly, it causes the originally dispersed iron in the slag to aggregate and settle, facilitating subsequent magnetic separation and achieving the goal of reducing iron content.

[0031] In some embodiments, the titanium-containing slag comprises, by mass percentage: 9-25% Ti, 1-10% Fe, 3-12% Mg, 2-20% Ca, 7-14% Si, 6-8% Al, and 0.1-1% TV.

[0032] In some embodiments, the vanadium-containing tailings, by mass percentage, comprises: 10-20% TV, 12-25% Ti, 2-5% Cl, 4-7% Si, 1-6% Fe, 2-4% Al, 5-10% Ca, and 1-3% Mg.

[0033] In some embodiments, the predetermined time in step S1 is 20 to 50 minutes.

[0034] In some embodiments, in step S1, vanadium-containing tailings and iron raw materials are added immediately after the hot titanium-containing slag is added to the electric furnace.

[0035] In some embodiments, in step S1, based on 100 parts by weight of titanium-containing slag, the amounts of vanadium-containing tailings and iron raw materials added are 5 to 40 parts by weight and 1 to 5 parts by weight, respectively.

[0036] In some embodiments, the amount of titanium-containing slag added in step S1 is 100 parts by weight, and the amount of carbonaceous reducing agent added in step S2 is 10 to 30 parts by weight.

[0037] In some embodiments, the reduction carbonization time in step S2 is 1 to 6 hours.

[0038] In some embodiments, in step S2, the carbonaceous reducing agent is at least one of anthracite, coke, petroleum coke and graphite, and wherein the fixed carbon content is not less than 75%; and / or the particle size of the carbonaceous reducing agent is not greater than 3 mm.

[0039] In some embodiments, step S3 includes performing post-processing sequentially: cooling, crushing, and magnetic separation.

[0040] In some embodiments, in step S3, the particle size is crushed to less than 80 mesh, preferably between 100 and 240 mesh; and / or when performing magnetic separation, the magnetic field strength is controlled to be 500 to 3000 Gs, preferably 500 to 1500 Gs, to ensure a better separation effect.

[0041] In summary, this invention provides a method for recovering iron, vanadium, and titanium from furnace slag. This method uses titanium-containing furnace slag from vanadium-titanium magnetite ironmaking and vanadium-containing tailings obtained after vanadium removal from titanium tetrachloride as raw materials. It can recover titanium resources from these two types of slag to prepare titanium carbide, which can be further chlorinated to prepare titanium tetrachloride. Furthermore, by combining vanadium and iron, it can reduce the iron content in the entire furnace slag while recovering vanadium, thus ensuring the product quality and stable operation of the entire process.

[0042] This invention converts titanium in titanium-containing slag and vanadium-containing tailings into titanium carbide slag, which can be chlorinated at a relatively low temperature (500℃) without calcium and magnesium participating in the chlorination process. On one hand, it transforms the titanium in both types of slag into titanium tetrachloride, an indispensable raw material for the titanium industry, effectively utilizing the titanium resources in the slag. On the other hand, by introducing vanadium-containing tailings and iron raw materials, the iron in the titanium-containing slag combines with vanadium to form a ferrovanadium alloy, recovering vanadium resources from the slag and reducing the overall iron content, ensuring the product quality and stable operation of the entire process. This is of great significance for alleviating environmental pressures on enterprises and improving the comprehensive utilization rate of vanadium and titanium resources.

[0043] The following description is based on specific embodiments.

[0044] Example 1

[0045] The titanium-containing slag processed in this embodiment mainly contains (by mass fraction): 9% Ti, 1.5% Fe, 3.8% Mg, 19.7% Ca, 13.6% Si, 8% Al, and 0.23% V. The vanadium-containing tailings mainly contain (by mass fraction): 10.9% V, 13.2% Ti, 3.8% Cl, 6.2% Si, 5.6% Fe, 9.2% Ca, 2.4% Mg, and 3.8% Al. The carbonaceous reducing agent is a graphite carburizing agent with a fixed carbon content of 75% and a particle size of less than 3 mm. The main steps are as follows:

[0046] A. Add 10t of hot titanium-containing slag to the electric furnace, then add 1.3t of vanadium-containing tailings and 120kg of ferrous oxide, and heat at 1300℃ for 20min;

[0047] B. Add 1.25t of graphite recarburizer and continue reduction smelting at 1500℃ for 1.5h;

[0048] C. Remove slag, cool, and crush the cooled product to below 80 mesh;

[0049] D. Control the magnetic field strength to 3000 Gs, perform magnetic separation, and obtain titanium carbide slag and ferrovanadium products.

[0050] Example 2

[0051] The titanium-containing slag processed in this embodiment mainly comprises (by mass fraction): 15% Ti, 3.5% Fe, 6.1% Mg, 15% Ca, 10.3% Si, 7.2% Al, and 0.18% V. The vanadium-containing tailings mainly comprise (by mass fraction): 13% V, 21.2% Ti, 2.8% Cl, 4.6% Si, 3.4% Fe, 7.2% Ca, 1.7% Mg, and 2.8% Al. The carbonaceous reducing agent is coke powder, with a fixed carbon content of 85% and a particle size of less than 1 mm. The main steps are as follows:

[0052] A. Add 10t of hot titanium-containing slag to the electric furnace, then add 2.7t of vanadium-containing tailings and 250kg of ferrous oxide, and heat at 1350℃ for 30min.

[0053] B. Add 1.8t of coke powder and continue reduction smelting at 1600℃ for 3 hours;

[0054] C. Remove slag, cool, and crush the cooled product to below 80 mesh;

[0055] D. Control the magnetic field strength to 2000 Gs, perform magnetic separation, and obtain titanium carbide slag and ferrovanadium products.

[0056] Example 3

[0057] The titanium-containing slag processed in this embodiment mainly comprises (by mass fraction): 19% Ti, 10% Fe, 11.2% Mg, 2.5% Ca, 7.8% Si, 6.4% Al, and 0.92% V. The vanadium-containing tailings mainly comprise (by mass fraction): 15.4% V, 20.6% Ti, 4.7% Cl, 5.1% Si, 2.8% Fe, 5.6% Ca, 1.6% Mg, and 2.6% Al. The carbonaceous reducing agent is semi-coke, with a fixed carbon content of 80% and a particle size of less than 3 mm. The main steps are as follows:

[0058] A. Add 10t of hot titanium-containing slag to the electric furnace, then add 4t of vanadium-containing tailings and 400kg of ferrous oxide, and heat at 1450℃ for 40min.

[0059] B. Add 2.6t of semi-coke and continue reduction smelting at 1650℃ for 4.5h;

[0060] C. Remove slag, cool, and crush the cooled product to below 80 mesh;

[0061] D. Control the magnetic field strength to 1000 Gs, perform magnetic separation, and obtain titanium carbide slag and ferrovanadium products.

[0062] Example 4

[0063] The titanium-containing slag processed in this embodiment mainly comprises (by mass fraction): 23% Ti, 6.6% Fe, 10% Mg, 2.6% Ca, 7% Si, 7.6% Al, and 0.67% V. The vanadium-containing tailings mainly comprise (by mass fraction): 20% V, 16.1% Ti, 2.7% Cl, 4.5% Si, 2.3% Fe, 6.7% Ca, 1.6% Mg, and 2.7% Al. The carbonaceous reducing agent is anthracite, with a fixed carbon content of 90% and a particle size of less than 2 mm. The main steps are as follows:

[0064] A. Add 10t of hot titanium-containing slag to the electric furnace, then add 3.3t of vanadium-containing tailings and 330kg of ferrous oxide, and heat at 1500℃ for 50min;

[0065] B. Add 2.9t of anthracite and continue reduction smelting at 1700℃ for 6 hours;

[0066] C. Remove slag, cool, and crush the cooled product to below 80 mesh;

[0067] D. Control the magnetic field strength to 500 Gs, perform magnetic separation, and obtain titanium carbide slag and ferrovanadium products.

[0068] The titanium carbide slag obtained in Examples 1-4 above contains 10-30 wt% titanium carbide, and the titanium recovery rate can reach over 90%; the ferrovanadium product contains 5-75 wt% vanadium and iron, and the vanadium and iron recovery rate is 30%-80%. The finished titanium carbide slag obtained above can be directly transported to a low-temperature chlorination process for further chlorination to prepare titanium tetrachloride, and the resulting ferrovanadium product can be used as an alloying additive or catalyst.

[0069] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for recovering iron, vanadium and titanium from a slag, characterized in that, The steps are as follows, performed sequentially: S1, hot titanium-containing slag, vanadium-containing tailings and iron raw materials are added to an electric furnace and heated at 1300~1500℃ for a predetermined time; wherein the titanium-containing slag is a by-product obtained from vanadium-titanium magnetite after ironmaking in a blast furnace or non-blast furnace, the vanadium-containing tailings is the tailings remaining after vanadium removal by titanium tetrachloride refining, and the iron raw materials are ferrous oxide, ferric oxide and / or iron. S2, add a carbonaceous reducing agent to the electric furnace and perform reduction carbonization at 1500~1750℃, so that the titanium in the titanium-containing slag and the vanadium-containing tailings are converted into titanium carbide, and at the same time, the iron in the titanium-containing slag and the vanadium in the vanadium-containing tailings are combined to form ferrovanadium alloy. S3, slag is discharged and post-processed to obtain titanium carbide slag and ferrovanadium products, wherein the iron content in the titanium carbide slag is less than 1 wt%. The titanium-containing slag, by mass percentage, comprises: 9-25% Ti, 1-10% Fe, 3-12% Mg, 2-20% Ca, 7-14% Si, 6-8% Al, and 0.1-1% TV; The vanadium-containing tailings, by mass percentage, comprise: 10-20% TV, 12-25% Ti, 2-5% Cl, 4-7% Si, 1-6% Fe, 2-4% Al, 5-10% Ca, and 1-3% Mg. In step S1, with 100 parts by weight of titanium-containing slag, the amounts of vanadium-containing tailings and iron raw materials added are 5-40 parts by weight and 1-5 parts by weight, respectively. Based on the amount of titanium-containing slag added in step S1 being 100 parts by weight, the amount of carbonaceous reducing agent added in step S2 is 10 to 30 parts by weight.

2. The method according to claim 1, characterized in that, In step S1, the predetermined time is 20~50 minutes.

3. The method of claim 1, wherein, In step S2, the reduction carbonization time is 1~6 hours.

4. The method of claim 1, wherein, In step S2, the carbonaceous reducing agent is at least one of anthracite, coke, petroleum coke and graphite, and the fixed carbon content is not less than 75%.

5. The method of claim 1, wherein, In step S2, the particle size of the carbonaceous reducing agent is no greater than 3 mm.

6. The method according to claim 1, characterized in that, In step S3, the post-processing includes: sequentially performing cooling, crushing, and magnetic separation.

7. The method of claim 6, wherein, In step S3, the particles are crushed to a size of less than 80 mesh.

8. The method of claim 7, wherein, In step S3, the particles are crushed to a size between 100 and 240 mesh.

9. The method of claim 6, wherein, In step S3, during magnetic separation, the magnetic field strength is controlled to be 500~3000Gs.

10. The method of claim 9, wherein, In step S3, during magnetic separation, the magnetic field strength is controlled to be 500~1500Gs.