CN115341061B - Method for efficiently fluidizing and reducing vanadium titano-magnetite fine powder - Google Patents

Abstract

The invention belongs to the fields of chemical industry and metallurgy, and discloses a method for efficiently fluidizing and reducing vanadium titano-magnetite fine powder. According to the method, the vanadium titano-magnetite fine powder smaller than 0.1mm is added with the binder for granulation modification, so that the high-temperature reduction fluidization quality of the vanadium titano-magnetite fine powder is improved, the bonding loss is prevented, and the purpose of efficient reduction is achieved; the reduction tail gas is combusted, preheated and oxidized to form vanadium titano-magnetite, so that the gas utilization rate and the reduction rate are improved; the heat is provided for the heat curing process by the thermal oxidation tail gas through heat exchange between the thermal reduction ore and the reducing gas, so that the energy utilization rate of the system is improved. The method has the advantages of simple process, environmental protection, high resource utilization rate, energy utilization rate and reaction efficiency, and good economic and social benefits.

Description

A method for efficient fluidized reduction of vanadium-titanium magnetite fine powder

Technical field

The invention belongs to the fields of chemical industry and metallurgy, and particularly relates to a method for efficient fluidized reduction of vanadium titanium magnetite fine powder.

Background technique

As important rare resources and strategic materials, vanadium and titanium have a very wide range of uses. About 98% of the world's vanadium and 91% of the titanium are contained in vanadium-titanium magnetite. Therefore, vanadium-titanium magnetite has a very high comprehensive Use value.

In the current process of processing vanadium-titanium magnetite, due to the high technological maturity, the blast furnace method of smelting vanadium-titanium magnetite is in a dominant position. However, blast furnace smelting is extremely dependent on metallurgical coke and causes serious environmental pollution. With the shortage of coking coal resources, The cost of blast furnace smelting is gradually increasing. In addition, most of the vanadium in the vanadium-titanium magnetite smelted by the blast furnace method can selectively enter the molten iron, and the vanadium can be extracted through the converter for better recycling, while the titanium enters the blast furnace slag. The titanium-containing phase in the slag is complex and the particle size distribution is fine. This makes it difficult to recycle titanium resources. In order to get rid of the constraints of the shortage of coking coal resources on the development of vanadium-titanium magnetite smelting and adapt to the increasing environmental protection requirements, non-blast furnace smelting technology has become one of the research hotspots in vanadium-titanium magnetite smelting. Non-blast furnace smelting technologies mainly include direct reduction and smelting reduction. Smelting reduction refers to any method that does not use a blast furnace to smelt liquid pig iron. Compared with blast furnaces, smelting reduction only uses coal instead of coke. Its products are similar to those of blast furnaces, so there is also the problem of difficulty in recycling titanium resources.

Compared with blast furnace and smelting reduction, the direct reduction method for smelting vanadium-titanium magnetite can produce sponge iron and vanadium-containing titanium slag at a temperature lower than the melting temperature of iron ore, with lower energy consumption and the gangue composition in the ore remains unchanged. Melting and slagging are beneficial to the recycling of vanadium and titanium resources. Depending on the reducing agent, the direct reduction method can be divided into two types: coal-based and gas-based. Coal-based reduction mainly uses rotary kilns and rotary hearth furnaces as reactors, while gas-based reduction mainly uses shaft furnaces and fluidized beds. Compared with coal-based reduction, gas-based reduction has the advantages of low energy consumption and environmental friendliness. As a typical gas-based direct reduction reactor, the shaft furnace mainly uses lump ore and pellets as raw materials. With the shortage of high-grade and high-quality lump ore resources, the preparation of pellets has gradually become a necessary link in shaft furnace smelting. , the preparation process of pellets needs to go through steps such as pelletizing, green pellet screening, drying and preheating, roasting and consolidation, cooling and screening, etc., and the operation is complicated. Among them, the roasting and consolidation step usually needs to be carried out at around 1250°C, which consumes a lot of energy. high. Compared with the shaft furnace, the fluidized bed eliminates the need for pellet preparation and can directly process powdered ore. It has the advantages of high gas-solid phase mass and heat transfer efficiency and fast reduction rate. It is a promising method. Vanadium titanium magnetite smelting technology. In the past few decades, fluidized ironmaking has made great progress. Typical fluidized direct reduction ironmaking processes include FIOR process, FINMET process and CIRCORED process.

The FIOR process was designed and developed by Exxon Research and Engineering Company. Iron ore powder with a particle size less than 5mm passes through four fluidized bed reactors in sequence. The first-level fluidized bed preheats the ore powder to 760°C. The reduction temperature of the second- to fourth-level fluidized bed reactors is 690-780°C, and the pressure is 1.11MPa. The metallization rate of the reduced iron ore powder reaches 92% and can be hot-pressed into blocks (US5082251). The fluidized reduction gas is obtained from the steam reforming of natural gas. The H ₂ content exceeds 90%. It is mixed with the purified circulating gas and enters the four-stage fluidized bed reactor, followed by the third stage and the second stage. The bed is in a gas-solid countercurrent state. When reducing iron ore powder in the FIOR process, an appropriate amount of non-stick inert powder such as CaO, MgO, etc. needs to be added to prevent loss of flow.

The FINMET process was developed by FIOR Venezuela and VAI by improving the FIOR method. Iron ore powder with a particle size less than 12.7mm passes through four series-connected fluidized bed reactors in sequence and flows countercurrently with the fluidized reduction gas. The temperature of the first-stage fluidized bed reactor is about 550°C and gradually increases downward. The temperature of the fourth-stage fluidized bed reactor is about 800°C and the pressure is 1.1-1.4MPa. The metallization rate of the export product from the four-stage fluidized bed reaches 93%, and the C content is about 0.5-3% (US5833734). The fluidized reduction gas used consists of fresh gas and circulating gas obtained after natural gas steam reforming, and needs to be heated to 850°C before entering the four-stage reactor. In order to avoid bonding loss, the raw materials used in the FINMET process are mainly coarse mineral powders that are not easy to bond. The content of fine mineral powders (particle size less than 0.1mm) must be controlled within 20%, otherwise inert powders such as CaO and MgO need to be added. .

The CIRCORED process was developed by the German company Outotec (formerly Lurgi Metallurgie) based on the gas-based rapid direct reduction technology of iron ore powder. The reduction system consists of a primary circulating fluidized bed (CFB) and a secondary bubbling fluidized bed (FB) (US5527379, US5603748). The CFB reactor used in a plant with a production capacity of 500,000 tons/year has an outer diameter of 5.2m and a height of 29.6m. The outer diameter of the external circulation cyclone is 5.5m. The outer diameter of the FB reactor is 7.0m. The total length is 17.5m. The internal There are four material rooms. The fluidizing reducing gas is pure H ₂ . The reduction temperature of the first-stage rapid fluidized bed is 630-650°C, and the reduction temperature of the second-stage bubbling fluidized bed is about 680°C, with a pressure of 0.4MPa. The obtained reduced iron powder can be hot-pressed into blocks or directly used in powder metallurgy. As the only commercial hydrogen direct reduction technology in the world, in order to avoid bonding loss during the fluidized reduction of iron ore powder, the reduction temperature in the CIRCORED process is controlled below 680°C, and about 1 mm of iron that is not easy to bond is selected. Mineral powder as raw material.

In addition, many Chinese patents also propose fluidized direct reduction ironmaking processes, such as CN103667571B, CN103725819B, CN106319126B, CN106467930B, etc. For the gas-based direct reduction of iron ore, a typical gas-solid non-catalytic reaction, the kinetic process can be described by the unreacted core model (condensation core model), which is composed of different control steps (external diffusion, internal diffusion and interface) in the condensation model. The relationship between the complete conversion time of particles and the particle size under chemical reaction) shows that the smaller the particles, the shorter the complete conversion time required, that is, the faster the reduction reaction rate. According to the basic theory of gas-solid fluidization, the initial fluidization velocity of particles is proportional to the square of the particle size, that is, the smaller the particles, the less gas required to maintain the fluidized state. Therefore, in theory, the finer the raw material ore powder, the more beneficial it is for fluidized direct reduction. However, the above-mentioned fluidized direct reduction ironmaking process is only suitable for processing coarse ore powder that is not easy to bond, or it is necessary to add inert substances to inhibit the loss of fine ore powder. Flow, these will have a greater impact on the efficiency of fluidized reduction, and the advantages of efficient fluidized reduction cannot be fully utilized. This is mainly because fine mineral powder (less than 0.1mm) is easily bonded during the fluidized reduction process at high temperatures (above 600°C), forming agglomerates with larger particle sizes and depositing at the bottom of the fluidized bed, which will eventually lead to Loss of flow throughout the bed. Once loss of flow occurs, the reduction system will have to be stopped, which will cause great losses to production (Komatina M, Gudenau H W. Metalurgija, 2004, 10(204): 309-328).

Therefore, through process and technological innovation, it is necessary to improve the high-temperature reduction fluidization quality of vanadium titanium magnetite fine powder less than 0.1mm, prevent flow loss, improve reduction efficiency, reduce energy consumption, and save production costs, which is the key to realizing the realization of my country's vanadium titanium magnets. An important way to efficiently utilize minerals.

Contents of the invention

In view of the problems existing in the prior art, the object of the present invention is to provide a method for efficient fluidized reduction of vanadium titanium magnetite fine powder. The method can achieve efficient reduction of vanadium-titanium magnetite fine powder, has a simple process, is environmentally friendly, has high resource utilization rate, energy utilization rate and reaction efficiency, and has good economic and social benefits.

To achieve this goal, the present invention adopts the following technical solutions:

A method for efficient fluidized reduction of vanadium-titanium magnetite fine powder. The method includes a mixing and briquetting process 1, a thermal curing process 2, a crushing and screening process 3, a combustion pre-oxidation process 4, and a fluidized reduction process 5. , heat exchange process 6 and separation process 7, specifically including the following steps:

1) In the mixing and briquetting process 1, the vanadium titanium magnetite fine powder and/or the fine powder from the crushing and screening process 3 are mixed with a binder, ground and mixed evenly, and pressed into blocks;

2) In the thermal curing process 2, the pressed block is heated by the thermal oxidation tail gas from the combustion pre-oxidation process 4 to obtain a cured material;

3) In the crushing and screening process 3, the solidified material is crushed and screened to obtain coarse particles that meet the requirements of high-temperature fluidized reduction, and the remaining fine powder is returned to the mixing and briquetting process 1 for recycling;

4) In the combustion pre-oxidation process 4, air is introduced to fully burn the reduction tail gas from the fluidized reduction process 5, preheat and oxidize the coarse-grained ore powder, and obtain thermal oxidation ore and thermal oxidation tail gas. The thermal oxidation tail gas is heated and solidified. Process 2;

5) In the fluidized reduction process 5, the thermally oxidized ore is reduced by the thermal reducing gas from the heat exchange process 6, and at the same time, supplementary air is introduced for combustion and heat supplementation to obtain thermally reduced ore and reduction tail gas. The reduction tail gas is sent to the combustion pre-oxidation process. 4;

6) In the heat exchange step 6, the hot reducing ore exchanges heat with the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidized reduction step 5;

7) In the separation process 7, the cold reduced ore is separated to obtain reduced iron powder and vanadium-rich titanium material.

The total iron content in the vanadium titanium magnetite fine powder is 40-70%, the TiO ₂ content is 5-20%, and the particle size of the vanadium titanium magnetite fine powder is less than 0.1 mm.

In the mixing and briquetting process 1, the mixing method of mineral powder and binder is grinding and mixing. The mixture is formed by pressing, where the pressure is 0.2-20MPa. The binder refers to one or a combination of water glass, bentonite, cement, biomass, humic acid, lime, starch, and polyvinyl alcohol. The added mass of the binder is 0.5-10% of the mass of the fine mineral powder.

In the thermal curing step 2, the curing temperature is 20-300°C and the curing time is 1-10 hours.

In the crushing and screening process 3, the screening particle size of the coarse mineral powder is controlled to be between 0.1-5mm.

In the combustion pre-oxidation process 4, the oxidation temperature is 600-800°C, the oxidation time is 0.5-2h, and the oxidation pressure is 0.1-1MPa.

In the fluidized reduction process 5, the reduction temperature is 600-800°C, the reduction time is 0.5-2h, and the reduction pressure is 0.1-1MPa.

In the heat exchange step 6, the reducing gas is coal gas or reformed gas, with _H2 and CO as active components.

Compared with the existing technology, the present invention has the following outstanding advantages:

(1) The present invention granulates vanadium titanium magnetite fine powder less than 0.1mm with a binder to obtain 0.1-5mm coarse particles for high-temperature fluidized reduction, which significantly improves the fluidized quality of its high-temperature reduction and is effective Suppresses flow loss and achieves efficient reduction of vanadium-titanium magnetite fine powder less than 0.1mm;

(2) The present invention improves gas utilization and reduction rate by preheating and oxidizing vanadium-titanium magnetite by reducing exhaust gas combustion;

(3) The present invention improves the energy utilization of the system by exchanging heat between thermally reduced ore and reducing gas, and the thermal oxidation tail gas provides heat and other waste heat for the thermal curing process.

Description of drawings

Figure 1 is a flow chart of a method for efficient fluidized reduction of vanadium titanium magnetite fine powder according to the present invention;

Figure 2 shows the change pattern of the metallization rate with time in the high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method described in Example 2;

Figure 3 shows the variation pattern of the metallization rate with time in the high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method described in Example 3;

Figure 4 shows the variation pattern of the metallization rate with time in the high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method described in Example 4.

Detailed ways

The present invention will be described in further detail below with reference to the drawings and specific embodiments.

Example 1

As shown in Figure 1, a method for efficient fluidized reduction of vanadium titanium magnetite fine powder, the method includes a mixing and briquetting process 1, a thermal curing process 2, a crushing and screening process 3, a combustion pre-oxidation process 4, Fluidized reduction process 5, heat exchange process 6 and separation process 7 specifically include the following steps:

1) In the mixing and briquetting process 1, the vanadium titanium magnetite fine powder and/or the fine powder from the crushing and screening process 3 are mixed with a binder, ground and mixed evenly, and pressed into blocks;

2) In the thermal curing process 2, the pressed block is heated by the thermal oxidation tail gas from the combustion pre-oxidation process 4 to obtain a cured material;

3) In the crushing and screening process 3, the solidified material is crushed and screened to obtain coarse particles that meet the requirements of high-temperature fluidized reduction, and the remaining fine powder is returned to the mixing and briquetting process 1 for recycling;

4) In the combustion pre-oxidation process 4, air is introduced to fully burn the reduction tail gas from the fluidized reduction process 5, preheat and oxidize the coarse-grained ore powder, and obtain thermal oxidation ore and thermal oxidation tail gas. The thermal oxidation tail gas is heated and solidified. Process 2;

5) In the fluidized reduction process 5, the thermally oxidized ore is reduced by the thermal reducing gas from the heat exchange process 6, and at the same time, supplementary air is introduced for combustion and heat supplementation to obtain thermally reduced ore and reduction tail gas. The reduction tail gas is sent to the combustion pre-oxidation process. 4.

6) In the heat exchange step 6, the hot reducing ore exchanges heat with the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidized reduction step 5.

7) In the separation process 7, the cold reduced ore is separated to obtain reduced iron powder and vanadium-rich titanium material.

Example 2

This embodiment adopts an efficient fluidized reduction method of vanadium titanium magnetite fine powder described in Example 1. First, add vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content about 40%, _TiO2 content about 20%) into 2% water glass, grind and mix evenly, and press it into blocks at 0.2MPa, and then place it Cured at 300°C for 1 hour to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in air at 600°C for 2 hours with an oxidation pressure of 1MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 600°C for 2 hours, and the reduction pressure is 1MPa to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore. As shown in Figure 2, the metallization rate changes with time during high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method of the present invention. Vanadium-titanium magnetite fine powder smaller than 0.1mm cannot be fluidized and reduced normally under experimental conditions, but the modified material of the method of the present invention can be fluidized and reduced stably for 2 hours to a metallization rate of about 90%. In addition, the fluidized reduction rate of the modified material of the method of the present invention is significantly higher than that of vanadium-titanium magnetite fine powder less than 0.1 mm.

Example 3

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, add 10% humic acid to vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content is about 70%, _TiO2 content is about 5%), grind and mix evenly, and press it into blocks at 20MPa, and then place it Cured at 200°C for 2 hours to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in air at 800°C for 0.5h with an oxidation pressure of 0.1MPa to obtain thermal oxidized ore. The thermally oxidized ore is fluidized and reduced in a reducing gas at 800°C for 0.5h with a reduction pressure of 0.1MPa to obtain the thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore. As shown in Figure 3, the metallization rate changes with time during high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method of the present invention. Vanadium-titanium magnetite fine powder smaller than 0.1mm cannot be fluidized and reduced normally under experimental conditions, but the modified material of the method of the present invention can be stably fluidized and reduced for 0.5h to a metallization rate of about 88%. In addition, the fluidized reduction rate of the modified material of the method of the present invention is significantly higher than that of vanadium-titanium magnetite fine powder less than 0.1 mm.

Example 4

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, add 0.5% cement to the vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content is about 62%, _TiO2 content is about 15%) and the fine powder from the crushing and screening process 3, grind and mix evenly. Press into blocks at 10 MPa, and then solidify at 20°C for 10 hours to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in air at 700°C for 1 hour with an oxidation pressure of 0.5MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 700°C for 1.5 hours, and the reduction pressure is 0.8MPa to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore. As shown in Figure 4, the metallization rate changes with time during high-temperature fluidized reduction of vanadium-titanium magnetite fine powder less than 0.1mm and the modified material of the method of the present invention. Vanadium-titanium magnetite fine powder smaller than 0.1mm cannot be fluidized and reduced normally under experimental conditions, but the modified material of the method of the present invention can be stably fluidized and reduced for 1.5 hours to a metallization rate of about 91%. In addition, the fluidized reduction rate of the modified material of the method of the present invention is significantly higher than that of vanadium-titanium magnetite fine powder less than 0.1 mm.

Example 5

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, add 5% bentonite fine powder of vanadium-titanium magnetite with a particle size less than 0.1mm (full iron content about 53%, _TiO2 content about 12%), grind and mix evenly, and press it into blocks at 15MPa, and then place it at 250 Cure for 5 hours at ℃ to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in the air at 600°C for 1 hour with an oxidation pressure of 0.1MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 800°C for 1 hour with a reduction pressure of 0.5MPa to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore.

Example 6

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content is about 45%, _TiO2 content is about 15%) is added to 10% biomass (treated with alkali solution), ground and mixed evenly and pressed at 15MPa Form into blocks and then solidify at 90°C for 3 hours to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in air at 640°C for 0.8h with an oxidation pressure of 0.3MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 780°C for 0.5h, and the reduction pressure is 0.8MPa to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore.

Example 7

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content is about 47%, _TiO2 content is about 10%) is added to 7% lime, ground and mixed evenly and pressed into blocks at 5MPa, and then placed at 50 Cure for 4 hours at ℃ to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in the air at 680°C for 1 hour with an oxidation pressure of 0.4MPa to obtain thermal oxidized ore. Thermal oxidized ore was fluidized and reduced in reducing gas at 730°C for 1.2 hours with a reduction pressure of 0.6MPa to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore.

Example 8

This embodiment adopts a method for efficient fluidized reduction of vanadium titanium magnetite fine powder described in Example 1. First, vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content about 53%, _TiO2 content about 14%) is added to 5% starch, ground and mixed evenly and pressed into blocks at 3MPa, and then placed at 180 Cure for 6 hours at ℃ to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in the air at 660°C for 1.5 hours with an oxidation pressure of 0.1MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 800°C for 1.8 hours, with a reduction pressure of 0.3MPa, to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore.

Example 9

This embodiment adopts an efficient fluidized reduction method of vanadium titanium magnetite fine powder described in Example 1. First, add 7% polyvinyl alcohol to vanadium-titanium magnetite fine powder with a particle size less than 0.1mm (full iron content is about 63%, _TiO2 content is about 8%), grind and mix evenly, and press it into blocks at 8MPa, and then place it Cured at 130°C for 3 hours to obtain cured material. The solidified material is crushed and screened to obtain coarse particles of 0.1-5mm, which are then oxidized in air at 600°C for 0.8h with an oxidation pressure of 0.7MPa to obtain thermal oxidized ore. Thermal oxidized ore is fluidized and reduced in reducing gas at 800°C for 1.7 hours, with a reduction pressure of 0.2MPa, to obtain thermally reduced ore. After heat exchange and separation, reduced iron powder and vanadium-rich titanium material can be obtained from the thermally reduced ore.

In the present invention, if % is not stated, it is mass percentage content.

This method can be realized by the upper and lower limits of the interval values of the process parameters (such as temperature, time, etc.) and the interval values of the present invention, and the embodiments will not be listed one by one here.

Contents not described in detail in the present invention may adopt conventional technical knowledge in the field.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and they shall all be covered by the scope of the present invention. within the scope of the claims.

Claims (5)

1. The method comprises a mixing briquetting process (1), a heat curing process (2), a crushing and screening process (3), a combustion pre-oxidation process (4), a fluidization reduction process (5), a heat exchange process (6) and a separation process (7), and specifically comprises the following steps of:

1) In the mixing and briquetting process (1), vanadium titano-magnetite fine powder with the particle size smaller than 0.1mm and/or fine powder from the crushing and screening process (3) are added with a binder, and are evenly mixed by grinding, and are pressed into blocks; the addition mass of the binder is 0.5-10% of the mass of the fine mineral powder;

2) In the heat curing process (2), heating the pressed block to 20-300 ℃ through the thermal oxidation tail gas from the combustion pre-oxidation process (4) to obtain a cured material;

3) In the crushing and screening process (3), the solidified material is crushed and screened to obtain coarse particle mineral powder with the particle size of 0.1-5mm, and the rest fine powder is returned to the mixing and briquetting process (1) for recycling;

4) In the combustion pre-oxidation step (4), introducing air to fully combust the reduction tail gas from the fluidization reduction step (5), preheating and oxidizing coarse particle mineral powder at 600-800 ℃ to obtain thermally oxidized ore and thermally oxidized tail gas, and sending the thermally oxidized tail gas to the thermal curing step (2); in the combustion pre-oxidation step (4), the oxidation time is 0.5-2h, and the oxidation pressure is 0.1-1MPa;

5) In the fluidized reduction process (5), the thermally oxidized ore is reduced at 600-800 ℃ by hot reducing gas from the heat exchange process (6), and supplementary air is introduced to burn and supplement heat at the same time, so that thermally reduced ore and reduced tail gas are obtained, and the reduced tail gas is sent to the combustion pre-oxidation process (4); in the fluidized reduction process (5), the reduction time is 0.5-2h, and the reduction pressure is 0.1-1MPa;

6) In the heat exchange process (6), heat exchange is carried out between the hot reducing ore and the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidization reduction process (5);

7) In the separation process (7), the cold reduced ore is separated to obtain reduced iron powder and vanadium-titanium-rich material.

2. The method for high-efficiency fluidization reduction of vanadium titano-magnetite fine powder according to claim 1, wherein the content of total iron in the vanadium titano-magnetite fine powder is 40-70%, and the content of TiO is ₂ The content is 5-20%.

3. The method for high-efficiency fluidization reduction of vanadium titano-magnetite fine powder according to claim 1 or 2, wherein in the mixing and briquetting process (1), the mixing method of mineral powder and binder is grinding and mixing; the mixture is formed by pressing, wherein the pressure is 0.2-20MPa; the binder is one or a combination of a plurality of sodium silicate, bentonite, cement, biomass, humic acid, lime, starch and polyvinyl alcohol.

4. The method for efficient fluidization reduction of fine powder of vanadium titano-magnetite according to claim 1 or 2, wherein the curing time is 1 to 10 hours in the heat curing process (2).

5. The method for efficient fluidized reduction of vanadium titano-magnetite fine powder according to claim 1 or 2, wherein in the heat exchanging step (6), the reducing gas is gas or reformed gas, and H is used as the reducing gas ₂ And CO as an active ingredient.