Method for producing titanium-rich direct reduced iron and high-titanium slag by using vanadium-titanium magnetite

Abstract

The present invention relates to the technical field of iron making. Specifically disclosed is a method for producing titanium-rich direct reduced iron and high-titanium slag by using vanadium-titanium magnetite, comprising: processing raw vanadium-titanium magnetite ore into a vanadium-titanium iron concentrate powder and a titanium concentrate powder, mixing the powders with a binder to prepare iron-titanium concentrate composite green pellets, and then performing oxidation roasting on the iron-titanium concentrate composite green pellets to obtain iron-titanium concentrate composite high-titanium pellets having a compressive strength greater than 2000 N per pellet and a reduction expansion rate less than 20%; and subjecting the iron-titanium concentrate composite high-titanium pellets to a direct reduction reaction in a shaft furnace to obtain titanium-rich direct reduced iron having a metallization rate greater than or equal to 85%. The method further comprises subjecting the obtained titanium-rich direct reduced iron to smelting separation in a smelting-separation electric furnace to obtain molten iron and high-titanium slag. In the present invention, by preparing iron-titanium concentrate composite high-titanium pellets that meet direct reduction smelting requirements in a gas-based shaft furnace and applying the iron-titanium concentrate composite high-titanium pellets to direct reduction in the gas-based shaft furnace to produce titanium-rich direct reduced iron, a high-quality titanium-rich raw material can be provided for smelting titanium slag in a smelting-separation electric furnace, effectively solving the problem of low recovery rate of titanium resources from existing vanadium-titanium magnetite.

Description

A method for producing titanium-rich direct reduced iron and high-titanium slag using vanadium-titanium magnetite. Technical Field

[0001] This invention relates to the field of ironmaking technology, specifically to the field of comprehensive utilization of vanadium-titanium magnetite resources, and particularly to a method for producing titanium-rich direct reduced iron and high-titanium slag from vanadium-titanium magnetite. Background Technology

[0002] The low-carbon and efficient utilization of titanium resources in vanadium-titanium magnetite is key to the green development of the titanium-iron circular economy industrial chain. After beneficiation, vanadium-titanium magnetite yields vanadium-titanium iron concentrate and titanium concentrate. Currently, the comprehensive utilization processes for vanadium-titanium magnetite resources are mainly divided into two processes: blast furnace-converter smelting of vanadium-titanium iron concentrate for iron and vanadium extraction, and pre-reduction-electric furnace smelting of titanium concentrate for titanium extraction. However, in the "blast furnace-converter process," all TiO2 in the raw materials enters the slag, forming high-titanium slag with a TiO2 content of 22-25%, which is difficult to utilize as a resource, resulting in a huge waste of 54% of the total titanium resources and causing significant CO2 emissions. The "pre-reduction-electric furnace process" is a non-blast furnace smelting process with advantages such as high recovery rate of valuable elements and low environmental impact. It has good application prospects for the low-carbon comprehensive utilization of complex symbiotic ores like vanadium-titanium magnetite. However, currently, the pre-reduction of titanium concentrate pellets mainly uses coal-based direct reduction processes such as rotary kilns and rotary hearth furnaces, which have problems such as high energy consumption, large CO2 emissions, low production capacity, and poor product quality. Gas-based vertical shaft furnace direct reduction process has advantages such as cleanliness, high efficiency, and stable product performance, and it helps to improve the TiO2 grade in subsequent titanium slag, becoming an important development direction for vanadium-titanium magnetite pre-reduction processes.

[0003] High-quality pellets are essential for the efficient and smooth operation of gas-based vertical shaft furnace direct reduction. However, vanadium-titanium magnetite, due to its complex composition and structure, is difficult to pelletize and roast, and is prone to expansion, pulverization, and agglomeration during reduction. Currently, patents concerning the preparation process of vanadium-titanium pellets for gas-based vertical shaft furnace direct reduction mainly include CN107058727A and CN103361481A. Among them, patent CN107058727A uses vanadium-titanium magnetite ore as raw material, while patent CN103361481A uses vanadium-titanium iron concentrate as raw material. However, the process suffers from problems such as low TiO2 content in the prepared pellets, making it difficult to guarantee the TiO2 grade in the subsequent electric furnace titanium slag. Regarding the direct reduction and recovery of valuable resources from vanadium-titanium magnetite, patent CN109136588A provides a method for producing high-titanium slag through direct reduction of titanium concentrate in a gas-based vertical shaft furnace. This method uses titanium concentrate as raw material to prepare pellets and is applied to a direct reduction-induction furnace melting process. Although it can obtain high-grade titanium slag, it cannot simultaneously achieve effective recovery of titanium resources from vanadium-titanium iron concentrate powder. Patent CN101575677A provides a method for producing titanium-rich materials and steel products using titanium ore. Although it can effectively recover various valuable elements from the inner and outer surfaces of vanadium-titanium magnetite ore and weathered ore or titanium sand ore, this method adds a carbonaceous reducing agent during pellet preparation, which introduces ash, reduces the grade of titanium slag, and easily leads to the formation of a large amount of glassy phase in the titanium slag, destroying its activity. It also generates CO2 pollutants during the pre-reduction process. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for producing titanium-rich direct reduced iron using vanadium-titanium magnetite. This method involves preparing high-titanium composite pellets of iron-titanium concentrate that meet the requirements of gas-based vertical shaft furnace direct reduction smelting, and applying these pellets to the gas-based vertical shaft furnace for direct reduction to produce titanium-rich direct reduced iron, thus providing high-quality titanium-rich raw materials for titanium slag smelting in electric arc furnaces.

[0005] To achieve the above and other related objectives, the present invention provides a method for producing titanium-rich direct reduced iron using vanadium-titanium magnetite, comprising the following steps:

[0006] 1) Preparation of high-titanium composite pellets from iron-titanium concentrate:

[0007] Vanadium-titanium magnetite ore is processed into vanadium-titanium iron concentrate powder and titanium concentrate powder;

[0008] The vanadium-titanium iron concentrate powder, titanium concentrate powder and binder are mixed to prepare iron-titanium concentrate composite green pellets, and then oxidatively roasted to obtain iron-titanium concentrate composite high titanium pellets.

[0009] The iron-titanium concentrate composite high-titanium pellets have a compressive strength greater than 2000 N / piece and a reduction expansion rate of less than 20%.

[0010] 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate:

[0011] The iron-titanium concentrate composite high-titanium pellets are directly reduced in a gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%.

[0012] Furthermore, in step 1), the vanadium-titanium magnetite ore is crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder.

[0013] Furthermore, the vanadium-titanium iron concentrate powder meets at least one of the following indicators: by mass fraction, the proportion of powder with a particle size less than 0.074 mm is greater than or equal to 80%, the total iron content is greater than or equal to 50%, and the TiO2 content is greater than or equal to 9%.

[0014] Furthermore, the titanium concentrate powder meets at least one of the following indicators: by mass fraction, the proportion of powder with a particle size less than 0.074 mm is greater than or equal to 80%, and the TiO2 content is greater than or equal to 45%.

[0015] Furthermore, the iron-titanium concentrate composite green pellets meet at least one of the following criteria: by mass fraction, the proportion of particles with a diameter of 8-16 mm is greater than or equal to 90%, and the moisture content is 7.5%-10.5%.

[0016] Furthermore, in step 1), when preparing the iron-titanium concentrate composite green pellets, the mass ratio of the vanadium-titanium iron concentrate powder to the titanium concentrate powder is 10-80:20-90.

[0017] Furthermore, in step 1), when preparing the iron-titanium concentrate composite green pellets, the ratio of the total mass of the vanadium-titanium iron concentrate powder and titanium concentrate powder to the mass of the binder is 100:1 to 2.

[0018] Further, in step 1), the mass ratio of the vanadium-titanium iron concentrate powder, titanium concentrate powder and binder in the iron-titanium concentrate composite pellets is 10-80:20-90:1-2.

[0019] Furthermore, the vanadium-titanium iron concentrate powder and titanium concentrate powder are dried before being mixed with the binder; preferably, the drying conditions of the vanadium-titanium iron concentrate powder and titanium concentrate powder include at least one of the following conditions: drying temperature of 150-300°C and drying time of 3-5 hours.

[0020] Furthermore, in step 1), the process of obtaining iron-titanium concentrate composite high-titanium pellets by oxidative roasting of the iron-titanium concentrate composite green pellets includes preheating and roasting steps in sequence.

[0021] Furthermore, in step 1), the preheating conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions: preheating temperature of 850-950℃ and preheating time of 8-25 minutes.

[0022] Further, in step 1), the roasting conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions: roasting temperature of 1200-1350℃, roasting time of 20-50 minutes, and roasting atmosphere of oxidizing atmosphere.

[0023] Furthermore, in step 1), before the preheating process, the iron-titanium concentrate composite green pellets are dried; preferably, the drying conditions of the iron-titanium concentrate composite green pellets include at least one of the following conditions: drying temperature of 150-300°C and drying time of 2-5 hours.

[0024] Furthermore, in step 1), after roasting, the iron-titanium concentrate composite high-titanium pellets are obtained by cooling.

[0025] Furthermore, in step 2), the direct reduction process conditions of the gas-based vertical furnace include at least one of the following conditions: the direct reduction temperature is 950-1050℃, and the direct reduction time is 3-5 hours.

[0026] Furthermore, in step 2), the iron-titanium concentrate composite high-titanium pellets are first subjected to slurry spraying treatment, and then subjected to a gas-based vertical furnace direct reduction process to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%.

[0027] Furthermore, in step 2), the iron-titanium concentrate composite high-titanium pellets are directly reduced with reducing gas in a gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%.

[0028] Furthermore, the reducing gas meets at least one of the following criteria: the volume ratio of H2 and CO is greater than or equal to 80%; the volume ratio of H2 and CO is 1.5% to 4%; and the oxidation degree is less than or equal to 10%, wherein the oxidation degree is calculated according to the following formula:

[0029] Degree of oxidation = V1 / V2

[0030] In the formula, V1 represents the total volume of CO2 and H2O in the reducing gas, and V2 represents the total volume of CO and H2 in the reducing gas.

[0031] The present invention also provides a method for producing high-titanium slag using titanium-rich direct reduced iron, comprising: melting the titanium-rich direct reduced iron produced by the method described above in a melting electric furnace to obtain molten iron and high-titanium slag, wherein the TiO2 content of the obtained high-titanium slag is greater than or equal to 70% by mass fraction.

[0032] As described above, the method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite of the present invention has the following beneficial effects:

[0033] The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite provided by this invention differs from the conventional process of separately smelting vanadium-titanium iron concentrate powder and titanium concentrate powder obtained after grinding and beneficiation of vanadium-titanium magnetite ore. Instead, it first mixes these ore powders to prepare composite high-titanium iron-titanium concentrate pellets that meet the requirements of gas-based vertical shaft furnace direct reduction smelting. These pellets are then applied to a gas-based vertical shaft furnace for direct reduction to produce titanium-rich direct reduced iron, achieving a metallization rate of ≥85% and providing high-quality titanium-rich raw materials for titanium slag smelting in electric arc furnaces. Subsequently, the resulting titanium-rich direct reduced iron is used for electric arc furnace smelting to obtain high-titanium slag with TiO2 ≥70%, suitable for titanium dioxide production, thus effectively solving the problem of low titanium resource recovery rate in existing vanadium-titanium magnetite ore. Attached Figure Description

[0034] Figure 1 shows a schematic diagram of the process flow for producing titanium-rich direct reduced iron using vanadium-titanium magnetite in Examples 1-3 of the present invention. Detailed Implementation

[0035] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] In this invention, unless otherwise stated, the term "multiple" means two or more.

[0037] The character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0038] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0039] One embodiment of the present invention provides a method for producing titanium-rich direct reduced iron using vanadium-titanium magnetite, comprising the following steps:

[0040] 1) Preparation of high-titanium composite pellets from iron-titanium concentrate:

[0041] Vanadium-titanium magnetite ore is processed into vanadium-titanium iron concentrate powder and titanium concentrate powder;

[0042] The vanadium-titanium iron concentrate powder, titanium concentrate powder and binder are mixed to prepare iron-titanium concentrate composite green pellets, and then oxidatively roasted to obtain iron-titanium concentrate composite high titanium pellets.

[0043] The iron-titanium concentrate composite high-titanium pellets have a compressive strength >2000N / pellet and a reduction expansion rate <20%.

[0044] 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate:

[0045] The iron-titanium concentrate composite high-titanium pellets are directly reduced in a gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate of ≥85%.

[0046] The method provided by the above embodiments of the present invention first prepares vanadium-titanium magnetite into vanadium-titanium iron concentrate powder and titanium concentrate powder, then mixes them with a binder to form iron-titanium concentrate composite green pellets, and then oxidizes and roasts them to obtain iron-titanium concentrate composite high-titanium pellets with a compressive strength >2000N / pellet and a reduction expansion rate <20%. These iron-titanium concentrate composite high-titanium pellets meet the requirements of gas-based vertical shaft furnace direct reduction smelting. When applied to gas-based vertical shaft furnace direct reduction to produce titanium-rich direct reduced iron, a metallization rate ≥85% can be achieved, and high-quality titanium-rich raw materials can be provided for the smelting of titanium slag in electric arc furnaces. Subsequently, the titanium-rich direct reduced iron obtained can be used for electric arc furnace smelting to obtain high-titanium slag with TiO2 ≥70%, which is suitable for the production of titanium dioxide, thereby effectively solving the problem of low titanium resource recovery rate in existing vanadium-titanium magnetite.

[0047] Furthermore, compared with existing technologies (such as CN107058727A, CN103361481A, CN109136588A, CN101575677A), the method provided by the above embodiments of the present invention also has the following advantages:

[0048] 1. The high-titanium composite pellets of iron-titanium concentrate obtained have a higher TiO2 content than pellets obtained directly from vanadium-titanium magnetite, which can provide high-quality titanium-rich raw materials for subsequent smelting of titanium slag in electric furnaces, thereby improving the TiO2 grade in the smelting titanium slag of electric furnaces.

[0049] 2. By mixing vanadium-titanium iron concentrate powder and titanium concentrate powder made from vanadium-titanium magnetite ore to form green pellets, and then oxidizing and roasting them, composite high-titanium iron-titanium concentrate pellets are obtained. This can fully utilize the titanium resources in vanadium-titanium iron concentrate while obtaining high-grade electric furnace slag, thus achieving effective recovery of titanium resources in vanadium-titanium magnetite ore.

[0050] 3. No carbonaceous reducing agent was added during the preparation of iron-titanium concentrate composite high-titanium pellets, thus avoiding the introduction of ash to reduce the grade of titanium slag, causing the titanium slag to form a large amount of glass phase, destroying the activity of titanium slag, and also avoiding the generation of CO2 pollutants during the pre-reduction process.

[0051] In some embodiments, in step 1), the vanadium-titanium magnetite ore is crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder.

[0052] In some embodiments, the vanadium-titanium iron concentrate powder meets at least one of the following indicators: by mass fraction, the proportion of powder with a particle size <0.074 mm is ≥80%, the total iron content is ≥50%, and the TiO2 content is ≥9%.

[0053] In some embodiments, the titanium concentrate powder meets at least one of the following criteria: by mass fraction, the proportion of powder with a particle size <0.074 mm is ≥80%, and the TiO2 content is ≥45%.

[0054] Controlling the performance of vanadium-titanium iron concentrate powder and titanium concentrate powder according to the above indicators is, on the one hand, to prepare high-quality iron-titanium concentrate composite high-titanium pellets, and on the other hand, to increase the TiO2 content in the obtained iron-titanium concentrate composite high-titanium pellets, thereby obtaining higher-grade electric furnace slag and realizing the effective recovery of titanium resources in vanadium-titanium magnetite ore.

[0055] In some embodiments, the iron-titanium concentrate composite green pellets meet at least one of the following indicators: by mass fraction, the proportion of particles with a diameter of 8-16 mm is ≥90%, and the moisture content is 7.5%-10.5%. The particle size requirement for the iron-titanium concentrate composite green pellets helps to control the size of the composite high-titanium pellets within a suitable range and improves particle size uniformity, which is beneficial for the full progress of the subsequent direct reduction reaction. Controlling the moisture content helps to ensure the green pellets can agglomerate; if the moisture content is too high, agglomeration is difficult, and if the moisture content is too low, cracking is likely during the drying process.

[0056] In some embodiments, in step 1), when preparing the iron-titanium concentrate composite green pellets, the mass ratio of the vanadium-titanium iron concentrate powder to the titanium concentrate powder is 10-80:20-90.

[0057] In some embodiments, in step 1), when preparing the iron-titanium concentrate composite green pellets, the ratio of the total mass of the vanadium-titanium iron concentrate powder and the titanium concentrate powder to the mass of the binder is 100:1 to 2.

[0058] In some embodiments, in step 1), the mass ratio of the vanadium-titanium iron concentrate powder, titanium concentrate powder and binder in the iron-titanium concentrate composite pellets is 10-80:20-90:1-2.

[0059] In some embodiments, the adhesive is selected from at least one of inorganic adhesives, organic adhesives, or composite adhesives (a combination of organic and inorganic adhesives). Inorganic adhesives include, but are not limited to, bentonite, sodium bentonite, calcium bentonite, quicklime, or water glass. Organic adhesives include, but are not limited to, perlido, modified starch, cornmeal, polyacrylamide, hydroxycellulose, carboxymethyl cellulose, lignin, or molasses. Composite adhesives are a combination of inorganic and organic adhesives.

[0060] In the above embodiments, controlling the mass ratio of vanadium-titanium iron concentrate powder to titanium concentrate powder according to the above proportions ensures the full utilization of vanadium-titanium magnetite ore-derived vanadium-titanium iron concentrate powder and titanium concentrate powder. It also guarantees the TiO2 content in the resulting high-titanium composite pellets, thereby obtaining high-grade electric furnace slag and achieving effective recovery of titanium resources from the vanadium-titanium magnetite ore. Simultaneously, controlling the amount of binder within the above range avoids both insufficient binder dosage (making it difficult to obtain high-strength pellets) and excessive binder dosage (causing adverse effects).

[0061] In some embodiments, the vanadium-titanium iron concentrate powder and titanium concentrate powder are dried before being mixed with the binder to reduce the moisture content of the powder, which helps to shorten the drying time required for subsequent green pellets and improve the quality of the pellets. Further, in some embodiments, the drying conditions of the vanadium-titanium iron concentrate powder and titanium concentrate powder include at least one of the following conditions: drying temperature of 150-300°C and drying time of 3-5 hours.

[0062] In some embodiments, step 1) involves the process of obtaining high-titanium iron ...

[0063] Furthermore, in some embodiments, in step 1), the preheating conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions: preheating temperature of 850-950°C and preheating time of 8-25 minutes.

[0064] Furthermore, in some embodiments, in step 1), the roasting conditions of the iron-titanium concentrate composite green pellets include at least one of the following conditions: roasting temperature of 1200-1350°C, roasting time of 20-50 minutes, and roasting atmosphere of oxidizing atmosphere.

[0065] In the above embodiments, by controlling the oxidation roasting process parameters according to the above conditions, it can be ensured that the obtained iron-titanium concentrate high-titanium pellets meet the requirements of gas-based vertical shaft furnace direct reduction smelting.

[0066] In some embodiments, step 1) further includes drying the iron-titanium concentrate composite green pellets before the preheating process to further reduce the moisture content of the green pellets, which is beneficial to shorten the time required for subsequent oxidation roasting, accelerate production efficiency, and improve pellet quality; furthermore, in some embodiments, the drying conditions of the iron-titanium concentrate composite green pellets include at least one of the following conditions: drying temperature of 150-300°C and drying time of 2-5 hours.

[0067] In some embodiments, after roasting in step 1), the iron-titanium concentrate composite high-titanium pellets are obtained by cooling; further, in some embodiments, the cooling method is selected from natural cooling or exhaust cooling, but is not limited to these.

[0068] In some embodiments, in step 2), the direct reduction process conditions of the gas-based vertical furnace include at least one of the following conditions: the direct reduction temperature is 950-1050°C, that is, the high-temperature reducing gas temperature is 950-1050°C; and the direct reduction time is 3-5 hours.

[0069] In some embodiments, in step 2), the iron-titanium concentrate composite high-titanium pellets are first subjected to a slurry spraying treatment, and then subjected to a gas-based vertical shaft furnace direct reduction process to obtain titanium-rich direct reduced iron with a metallization rate ≥85%. The main purpose of the slurry spraying treatment is to reduce the adhesion of the pellets in the vertical shaft furnace. Further, in some embodiments, the slurry spraying solution used for the slurry spraying treatment is selected from lime water, but is not limited to it; wherein, the lime water is prepared by mixing lime powder and water, preferably lime water containing 50-70 g / L lime powder. Even further, in some embodiments, the mass ratio of lime powder to the iron-titanium concentrate composite high-titanium pellets is 0.15-0.25:100.

[0070] In some embodiments, in step 2), the iron-titanium concentrate composite high-titanium pellets are directly reduced with reducing gas in a gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate of ≥85%.

[0071] Furthermore, in some embodiments, the reducing gas meets at least one of the following criteria: the volume percentage of H2 and CO is ≥80%; the volume ratio of H2 and CO is 1.5% to 4%; and the oxidation degree is less than or equal to ≤10%, wherein the oxidation degree is calculated according to the following formula:

[0072] Degree of oxidation = V1 / V2

[0073] In the formula, V1 represents the total volume of CO2 and H2O in the reducing gas, and V2 represents the total volume of CO and H2 in the reducing gas.

[0074] Controlling the performance of reducing gas according to the above-mentioned indicators is beneficial to the subsequent direct reduction reaction, improves the metallization rate of titanium-rich direct reduced iron, and provides high-quality titanium-rich raw materials for titanium slag smelting in electric arc furnaces.

[0075] Another embodiment of the present invention provides a method for producing high-titanium slag using titanium-rich direct reduced iron, comprising: melting the titanium-rich direct reduced iron produced by the method described in the above embodiments / examples in a melting electric furnace to obtain molten iron and high-titanium slag, wherein the obtained high-titanium slag has a TiO2 content of ≥70% by mass fraction, and is suitable for the production of titanium dioxide.

[0076] In addition, it should be noted that the compressive strength, reduction expansion rate, metallization rate, total iron / TiO2 / moisture content, powder / particle ratio, oxidation degree and other indicators mentioned in this invention can all be obtained by conventional or known methods recorded in the prior art, and will not be repeated here; other process parameters and details not mentioned in the method of this invention can be carried out in accordance with conventional or known methods in the field of metallurgical ironmaking, and will not be repeated here either.

[0077] The following specific examples illustrate the present invention in detail. It should also be understood that the following examples are only for specific illustrative purposes and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0078] The vanadium-titanium magnetite ore used in the following examples all comes from the Panxi region, but is not limited thereto. That is, the present invention does not impose special restrictions on the origin of vanadium-titanium magnetite ore, and vanadium-titanium magnetite ore from other regions may also be used.

[0079] Example 1

[0080] As shown in Figure 1, this embodiment provides a method for producing titanium-rich direct reduced iron and high-titanium slag using vanadium-titanium magnetite, including the following steps:

[0081] 1) Preparation of high-titanium composite pellets from iron-titanium concentrate:

[0082] The vanadium-titanium magnetite ore was crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder, respectively. The main chemical compositions of the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are shown in Table 1. By mass fraction, the total iron content of the vanadium-titanium iron concentrate powder is 56.50%, the TiO2 content is 12.53%, and the TiO2 content of the titanium concentrate powder is 48.80%. Meanwhile, the proportions of powder with a particle size <0.074 mm in the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are 91.3% and 92.1%, respectively.

[0083] Vanadium-titanium iron concentrate powder and titanium concentrate powder were dried at 150℃ for 4 hours, and then mixed with sodium-based bentonite as a binder at a mass ratio of 35:65:1.5 to prepare iron-titanium concentrate composite green pellets. The resulting iron-titanium concentrate composite green pellets had a moisture content of 9% and a particle size of 8-16 mm accounted for 92.5%.

[0084] Iron-titanium concentrate composite green pellets were sequentially dried at 180℃ for 5 hours, preheated at 900℃ for 15 minutes, calcined at 1200℃ for 20 minutes under an oxidizing atmosphere, and then naturally cooled to obtain iron-titanium concentrate composite high-titanium pellets. The obtained iron-titanium concentrate composite high-titanium pellets had a compressive strength of 2364 N / pellet and a reduction expansion rate of 7.89%.

[0085] 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate:

[0086] Take the iron-titanium concentrate composite high-titanium pellets obtained in step (1), use lime water containing 60g / L lime powder as the spraying solution, and perform spraying treatment according to the mass ratio of lime powder to iron-titanium concentrate composite high-titanium pellets of 0.15:100.

[0087] The iron-titanium concentrate composite high-titanium pellets, after being treated with slurry, were directly reduced in a vertical shaft furnace with a high-temperature reducing gas at 950℃ for 4 hours to obtain titanium-rich direct reduced iron. The metallization rate of the obtained titanium-rich direct reduced iron was 87.3%. The effective components H2+CO in the high-temperature reducing gas were 86.5%, the H2 / CO volume ratio was 1.8, and the oxidation degree was 7.5%.

[0088] The titanium-rich direct reduced iron obtained in step 2) is smelted in a melting electric furnace to obtain high-quality molten iron and high-titanium slag. The resulting high-titanium slag has a TiO2 content of ≥70% by mass fraction, making it suitable for titanium dioxide production.

[0089] Table 1. Main chemical components of vanadium-titanium iron concentrate and titanium concentrate obtained in Examples 1-3

[0090] Example 2

[0091] As shown in Figure 1, this embodiment provides a method for producing titanium-rich direct reduced iron and high-titanium slag using vanadium-titanium magnetite, including the following steps:

[0092] 1) Preparation of high-titanium composite pellets from iron-titanium concentrate:

[0093] The vanadium-titanium magnetite ore was crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder, respectively. The main chemical compositions of the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are shown in Table 1. By mass fraction, the total iron content of the vanadium-titanium iron concentrate powder is 56.50%, the TiO2 content is 12.53%, and the TiO2 content of the titanium concentrate powder is 48.80%. Meanwhile, the proportions of powder with a particle size <0.074 mm in the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are 92.5% and 91.8%, respectively.

[0094] Vanadium-titanium iron concentrate powder and titanium concentrate powder were dried at 180℃ for 3 hours, and then mixed with sodium-based bentonite as a binder at a mass ratio of 25:75:1.8 to prepare iron-titanium concentrate composite green pellets. The resulting iron-titanium concentrate composite green pellets had a moisture content of 9.5% and a particle size of 8-16 mm accounted for 93.2% of the total.

[0095] Iron-titanium concentrate composite green pellets were sequentially dried at 200℃ for 4 hours, preheated at 850℃ for 10 minutes, calcined at 1250℃ for 20 minutes under an oxidizing atmosphere, and then naturally cooled to obtain iron-titanium concentrate composite high-titanium pellets. The obtained iron-titanium concentrate composite high-titanium pellets had a compressive strength of 2513 N / pellet and a reduction expansion rate of 7.32%.

[0096] 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate:

[0097] Take the iron-titanium concentrate composite high-titanium pellets obtained in step (1), use lime water containing 55g / L lime powder as the spraying solution, and spray the pellets according to the mass ratio of lime powder to iron-titanium concentrate composite high-titanium pellets of 0.2:100.

[0098] The iron-titanium concentrate composite high-titanium pellets, after being treated with slurry, were directly reduced in a vertical shaft furnace with a high-temperature reducing gas at 1000℃ for 3.5 hours to obtain titanium-rich direct reduced iron. The metallization rate of the obtained titanium-rich direct reduced iron was 86.8%. The effective components of the high-temperature reducing gas were H2+CO, accounting for 88%, with an H2 / CO volume ratio of 2.0 and an oxidation degree of 6.8%.

[0099] The titanium-rich direct reduced iron obtained in step 2) is smelted in a melting electric furnace to obtain high-quality molten iron and high-titanium slag. The resulting high-titanium slag has a TiO2 content of ≥70% by mass fraction, making it suitable for titanium dioxide production.

[0100] Example 3

[0101] As shown in Figure 1, this embodiment provides a method for producing titanium-rich direct reduced iron and high-titanium slag using vanadium-titanium magnetite, including the following steps:

[0102] 1) Preparation of high-titanium composite pellets from iron-titanium concentrate:

[0103] The vanadium-titanium magnetite ore was crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder, respectively. The main chemical compositions of the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are shown in Table 1. By mass fraction, the total iron content of the vanadium-titanium iron concentrate powder is 56.50%, the TiO2 content is 12.53%, and the TiO2 content of the titanium concentrate powder is 48.80%. Meanwhile, the proportions of powder with a particle size <0.074 mm in the obtained vanadium-titanium iron concentrate powder and titanium concentrate powder are 90.8% and 91.5%, respectively.

[0104] Vanadium-titanium iron concentrate powder and titanium concentrate powder were dried at 150℃ for 4 hours, and then mixed with sodium-based bentonite as a binder at a mass ratio of 15:85:1.9 to prepare iron-titanium concentrate composite green pellets. The resulting iron-titanium concentrate composite green pellets had a moisture content of 9% and a particle size of 8-16 mm accounted for 93.5%.

[0105] Iron-titanium concentrate composite green pellets were sequentially dried at 250℃ for 4 hours, preheated at 900℃ for 15 minutes, calcined at 1250℃ for 25 minutes under an oxidizing atmosphere, and then naturally cooled to obtain iron-titanium concentrate composite high-titanium pellets. The obtained iron-titanium concentrate composite high-titanium pellets had a compressive strength of 2213 N / pellet and a reduction expansion rate of 8.14%.

[0106] 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate:

[0107] Take the iron-titanium concentrate composite high-titanium pellets obtained in step (1), use lime water containing 60g / L lime powder as the spraying solution, and perform spraying treatment according to the mass ratio of lime powder to iron-titanium concentrate composite high-titanium pellets of 0.2:100.

[0108] The iron-titanium concentrate composite high-titanium pellets, after being treated with slurry, were directly reduced in a vertical shaft furnace with a high-temperature reducing gas at 1025℃ for 4 hours to obtain titanium-rich direct reduced iron. The metallization rate of the obtained titanium-rich direct reduced iron was 86.5%. The effective components of the high-temperature reducing gas were H2+CO, with an H2 / CO volume ratio of 2.0 and an oxidation degree of 7.0%.

[0109] The titanium-rich direct reduced iron obtained in step 2) is smelted in a melting electric furnace to obtain high-quality molten iron and high-titanium slag. The resulting high-titanium slag has a TiO2 content of ≥70% by mass fraction, making it suitable for titanium dioxide production.

[0110] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for producing titanium-rich direct reduced iron using vanadium-titanium magnetite, characterized in that, Includes the following steps: 1) Preparation of high-titanium composite pellets from iron-titanium concentrate: Vanadium-titanium magnetite ore is processed into vanadium-titanium iron concentrate powder and titanium concentrate powder; The vanadium-titanium iron concentrate powder, titanium concentrate powder and binder are mixed to prepare iron-titanium concentrate composite green pellets, and then oxidatively roasted to obtain iron-titanium concentrate composite high titanium pellets. The iron-titanium concentrate composite high-titanium pellets have a compressive strength greater than 2000 N / piece and a reduction expansion rate of less than 20%. 2) Direct reduction of high-titanium composite pellets from iron-titanium concentrate: The iron-titanium concentrate composite high-titanium pellets are directly reduced in a gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%.

2. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 1, characterized in that: In step 1), the vanadium-titanium magnetite ore is crushed, ground, and screened to obtain vanadium-titanium iron concentrate powder and titanium concentrate powder. And / or, the vanadium-titanium iron concentrate powder meets at least one of the following indicators (A1) to (A3): (A1) By mass fraction, the proportion of powder with a particle size less than 0.074 mm is greater than or equal to 80%; (A2) The total iron content is greater than or equal to 50% by mass fraction; (A3) The TiO2 content is greater than or equal to 9% by mass fraction; And / or, the titanium concentrate powder meets at least one of the following indicators (B1) to (B2): (B1) By mass fraction, the proportion of powder with a particle size less than 0.074 mm is greater than or equal to 80%; (B2) The TiO2 content is greater than or equal to 45% by mass fraction; And / or, the iron-titanium concentrate composite green pellets meet at least one of the following indices (C1) to (C2): (C1) The moisture content is 7.5% to 10.5% by mass fraction; (C2) Particles with a diameter of 8–16 mm account for 90% or more.

3. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 1 or 2, characterized in that: In step 1), when preparing the iron-titanium concentrate composite green pellets, the mass ratio of the vanadium-titanium iron concentrate powder to the titanium concentrate powder is 10-80:20-90. And / or, in step 1), when preparing the iron-titanium concentrate composite green pellets, the ratio of the total mass of the vanadium-titanium iron concentrate powder and titanium concentrate powder to the mass of the binder is 100:1 to 2.

4. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 1, characterized in that: In step 1), the vanadium-titanium iron concentrate powder and titanium concentrate powder are dried before being mixed with the binder; And / or, in step 1), the process of obtaining iron-titanium concentrate composite high-titanium pellets by oxidative roasting of the iron-titanium concentrate composite green pellets includes preheating and roasting steps in sequence.

5. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 4, characterized in that: The drying conditions for the vanadium-titanium iron concentrate powder and titanium concentrate powder include at least one of the following conditions (a1) to (a2): (a1) The drying temperature is 150–300℃; (a2) Drying time is 3 to 5 hours; And / or, the preheating conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions (b1) to (b2): (b1) The preheating temperature is 850–950°C; (b2) The preheating time is 8 to 25 minutes; And / or, the roasting conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions (c1) to (c2): (c1) The calcination temperature is 1200~1350℃; (c2) The roasting time is 20 to 50 minutes; (c3) The roasting atmosphere is an oxidizing atmosphere.

6. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 4 or 5, characterized in that: In step 1), before the preheating process, the iron-titanium concentrate composite green pellets are dried; And / or, in step 1), after roasting, the iron-titanium concentrate composite high-titanium pellets are obtained by cooling.

7. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 6, characterized in that: The drying conditions for the iron-titanium concentrate composite green pellets include at least one of the following conditions (d1) to (d2): (d1) The drying temperature is 150–300℃; (d2) Drying time is 2 to 5 hours; And / or, the cooling method is selected from natural cooling or exhaust cooling.

8. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 1, characterized in that: Step 2) The process conditions include at least one of the following conditions (e1) to (e4): (e1) The direct reduction temperature is 950–1050℃; (e2) Direct reduction time is 3 to 5 hours; (e3) The iron-titanium concentrate composite high-titanium pellets are first sprayed and then directly reduced by gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%. (e4) The iron-titanium concentrate composite high-titanium pellets and reducing gas are directly reduced by gas-based vertical furnace to obtain titanium-rich direct reduced iron with a metallization rate greater than or equal to 85%.

9. The method for producing titanium-rich direct reduced iron from vanadium-titanium magnetite according to claim 8, characterized in that: In step 2), the reducing gas satisfies at least one of the following indices (D1) to (D3): (D1) The volume percentage of H2 and CO is greater than or equal to 80%; The volume ratio of (D2)H2 to CO is 1.5% to 4%; (D3) The degree of oxidation is less than or equal to 10%, which is calculated according to the following formula: Degree of oxidation = V1 / V2 In the formula, V1 represents the total volume of CO2 and H2O in the reducing gas, and V2 represents the total volume of CO and H2 in the reducing gas.

10. A method for producing high-titanium slag by direct reduction of iron with titanium-rich materials, characterized in that, include: The titanium-rich direct reduced iron produced by the method as described in any one of claims 1 to 9 is smelted in a smelting electric furnace to obtain molten iron and high-titanium slag, wherein the TiO2 content of the high-titanium slag is greater than or equal to 70% by mass fraction.

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