A method for reducing the agglomeration of pellets in the gas-based shaft furnace smelting of vanadium titano-magnetite

Abstract

The present application belongs to the field of vanadium-titanium magnetite gas-based shaft furnace smelting, and particularly relates to a method for reducing the agglomeration of vanadium-titanium magnetite pellets in gas-based shaft furnace smelting and a gas-based shaft furnace-electric furnace smelting and separation process for vanadium-titanium magnetite. The method for reducing the agglomeration of vanadium-titanium magnetite pellets in gas-based shaft furnace smelting comprises the following steps: Step 1: preparing shaped sintered calcium flux pellets; Step 2: uniformly mixing the shaped sintered calcium flux pellets prepared in Step 1 with vanadium-titanium magnetite oxidized pellets and then loading them into a gas-based shaft furnace for smelting. In the present application, the slag modifier in the smelting and separation process of the gas-based shaft furnace-electric furnace smelting and separation process for vanadium-titanium magnetite is separately pelletized and pre-added in the gas-based shaft furnace process, which can reduce the agglomeration of pellets in the shaft furnace smelting process, ensure normal discharging and good air permeability in the process of smelting vanadium-titanium magnetite pellets in the gas-based shaft furnace, and ensure the stable and smooth operation of the gas-based shaft furnace.

Description

Technical Field

[0001] This invention belongs to the field of vanadium-titanium magnetite gas-based vertical furnace smelting, specifically involving a method for reducing pellet adhesion in vanadium-titanium magnetite gas-based vertical furnace smelting and a gas-based vertical furnace-electric furnace smelting process for vanadium-titanium magnetite. Background Technology

[0002] Vanadium-titanium magnetite is a composite iron ore primarily composed of iron, titanium, and vanadium, possessing extremely high comprehensive utilization value. As an important iron ore resource in my country, non-blast furnace smelting of vanadium-titanium magnetite is receiving increasing attention. The gas-based shaft furnace-electric furnace smelting process is currently the most mature and widely used non-blast furnace smelting technology. This process can utilize large quantities of clean, hydrogen-rich gas and green electricity to achieve clean and efficient metallurgical separation of vanadium-titanium magnetite, meeting current carbon reduction requirements. Simultaneously, it avoids the use of coke resources required in blast furnace processes, eliminating sintering and coking processes, significantly reducing environmental pollution and environmental pressure, and demonstrating sustainable development capabilities.

[0003] Gas-based shaft furnaces are used to produce vanadium-titanium magnetite metallized pellets for subsequent electric furnace smelting. However, due to iron whisker growth and pressure from the overhead charge, the metallized pellets in gas-based shaft furnaces tend to agglomerate, causing problems such as uneven feeding and gas flow distribution, thus affecting the smooth operation of the gas-based shaft furnace. Therefore, reducing pellet agglomeration during the reduction process in gas-based shaft furnaces is one of the key issues for ensuring the smooth operation of vanadium-titanium magnetite smelting in gas-based shaft furnaces. Summary of the Invention

[0004] This invention addresses the problem of pellet agglomeration in the production of vanadium-titanium magnetite metallized pellets in gas-based vertical shaft furnaces. It proposes a method to reduce pellet agglomeration during the gas-based vertical shaft furnace smelting process by pre-adding calcium flux pellets required for electric furnace smelting, thereby ensuring smooth operation of existing vanadium-titanium magnetite gas-based vertical shaft furnaces.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] According to a first aspect of the present invention, a method for reducing pellet agglomeration in vanadium-titanium magnetite gas-based vertical shaft furnace smelting is provided, comprising the following steps:

[0007] Step 1: Prepare shaped and sintered calcium flux pellets;

[0008] Step 2: After uniformly mixing the shaped sintered calcium flux pellets prepared in Step 1 with vanadium-titanium magnetite oxide pellets, the mixture is loaded into a gas-based vertical shaft furnace for smelting.

[0009] According to some embodiments of the present invention, in step 1, the sintering calcium flux pellets are made from raw materials that can be calcined to obtain calcium oxide.

[0010] According to some embodiments of the present invention, in step 1, the sintering calcium flux pellets are prepared from one or more of quicklime, hydrated lime, and limestone.

[0011] According to some embodiments of the present invention, in step 1, the diameter of the sintered calcium flux pellets is controlled at 5-15 mm, and the compressive strength is above 2000 N.

[0012] According to some embodiments of the present invention, in step 1, the compressive strength of the sintered calcium flux pellets is above 2500N.

[0013] According to some embodiments of the present invention, in step 2, the amount of calcium flux pellets added for shaping and sintering is determined according to the basicity required for electric furnace smelting.

[0014] According to some embodiments of the present invention, the basicity required for electric furnace smelting is 0.2-1.2.

[0015] According to some embodiments of the present invention, in step 2, the amount of sintering calcium flux pellets added is between 2% and 10% by mass.

[0016] According to a second aspect of the present invention, a gas-based vertical shaft furnace-electric furnace smelting process for vanadium-titanium magnetite is provided, comprising the following steps:

[0017] Step 10: Prepare vanadium-titanium magnetite oxide pellets;

[0018] Step 20: Prepare shaped and sintered calcium flux pellets;

[0019] Step 30: The shaped sintered calcium flux pellets prepared in step 20 are uniformly mixed with the vanadium-titanium magnetite oxide pellets prepared in step 10 and then loaded into a gas-based vertical shaft furnace. Reducing gas is introduced for pre-reduction to obtain vanadium-titanium magnetite metallized pellets and calcium flux pellets.

[0020] Step 40: The vanadium-titanium magnetite metallized pellets and calcium flux pellets obtained in Step 30 are hotly charged into an electric furnace for electric furnace melting and separation to obtain vanadium-containing molten iron and titanium-containing slag.

[0021] According to some embodiments of the present invention, in step 40, no flux needs to be added.

[0022] By adopting the above technical solution, the present invention has the following beneficial effects:

[0023] This invention reduces pellet adhesion during the vertical furnace smelting process by separately pelletizing the slag conditioning agent in the smelting process of the vanadium-titanium magnetite gas-based vertical furnace-electric furnace smelting and adding it in advance in the gas-based vertical furnace process. This ensures normal feeding and good permeability during the vanadium-titanium magnetite pelletizing process in the gas-based vertical furnace, and ensures the stable and smooth operation of the gas-based vertical furnace. Attached Figure Description

[0024] Figure 1 A diagram is drawn to define the adhesion index (SI). Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] Specific embodiments of the invention are disclosed herein as needed; however, it should be understood that the embodiments disclosed herein are merely examples of the invention that may be implemented in various alternative forms. In the following description, various operating parameters and components are described in several contemplated embodiments. These specific parameters and components are provided as examples only and are not intended to be limiting.

[0027] According to a first aspect of the present invention, a method for reducing pellet agglomeration in vanadium-titanium magnetite gas-based vertical shaft furnace smelting is provided, comprising the following steps:

[0028] Step 1: Prepare shaped and sintered calcium flux pellets;

[0029] Step 2: After uniformly mixing the shaped sintered calcium flux pellets prepared in Step 1 with vanadium-titanium magnetite oxide pellets, the mixture is loaded into a gas-based vertical shaft furnace for smelting.

[0030] This invention pre-adds the slag conditioner (calcareous flux) typically used in the smelting process to the pre-reduction process of a gas-based vertical shaft furnace after it has been separately pelletized. Since the calcium flux pellets do not bond with the vanadium-titanium pellets, their addition reduces the contact between the vanadium-titanium pellets, thereby reducing pellet adhesion during the vertical shaft furnace smelting process. This ensures normal feeding and good permeability during the vanadium-titanium magnetite pelletizing process in the gas-based vertical shaft furnace, thus ensuring the stable and smooth operation of the gas-based vertical shaft furnace.

[0031] In step 1, the shaped sintered calcium flux pellets are made from raw materials that yield calcium oxide after calcination, with a calcium oxide content >95%. For example, in some embodiments, the shaped sintered calcium flux pellets are made from one or more of quicklime, hydrated lime, and limestone. The diameter of the shaped sintered calcium flux pellets needs to be controlled between 5-15 mm, and the compressive strength should be above 2000 N, preferably above 2500 N. Sufficient strength in the pellets prevents the furnace charge from being crushed by the material layer, reduces the generation of powder in the vertical furnace, maintains the permeability of the material layer, and facilitates the smooth operation of the vertical furnace.

[0032] In step 2, the amount of sintering calcium flux pellets added is determined based on the basicity required for electric furnace smelting. In some embodiments, the binary basicity range for electric furnace smelting can be 0.2-1.2. The mass fraction of the added sintering calcium flux pellets is generally between 2-10%.

[0033] Before adding sintering calcium flux pellets, the reduction-bonding index of gas-based vertical shaft furnace pellets at reduction temperatures of 900–1100℃ is 5–50. After adding sintering calcium flux pellets, the reduction-bonding index can be reduced to below 5, showing significant effect.

[0034] The reduction adhesion index is defined as follows: Pellet balls are placed in a crucible with pores at the bottom, a suitable load is applied, and the balls are reduced to the reduction endpoint at a specific temperature. After cooling, the pellets are removed, their total weight is measured, and a drop test is performed to calculate the adhesion index. The removed sample is divided into a bonded portion and an unbonded portion. Two or more pellets bonded together constitute the bonded portion. The weight of the bonded portion is weighed and recorded as the weight of the sample in the 0th drop. The bonded portion of the pellets is dropped from a height of 1 m, and the weight of the remaining bonded portion after the drop is measured. This is repeated 10 times. A graph is plotted showing the mass of bonded pellets relative to the total mass of the pellets after each drop, corresponding to the number of drops. Figure 1 The adhesion index (SI) is defined as follows: Figure 1 The percentage of the image occupied by the area enclosed by the mid-curve.

[0035] According to a second aspect of the present invention, a gas-based vertical shaft furnace-electric furnace smelting process for vanadium-titanium magnetite is provided, comprising the following steps:

[0036] Step 10: Prepare vanadium-titanium magnetite oxide pellets;

[0037] Step 20: Prepare shaped and sintered calcium flux pellets;

[0038] Step 30: The shaped sintered calcium flux pellets prepared in step 20 are uniformly mixed with the vanadium-titanium magnetite oxide pellets prepared in step 10 and then loaded into a gas-based vertical shaft furnace. Reducing gas is introduced for pre-reduction to obtain vanadium-titanium magnetite metallized pellets and calcium flux pellets.

[0039] Step 40: The vanadium-titanium magnetite metallized pellets and calcium flux pellets obtained in Step 30 are hotly charged into an electric furnace for electric furnace melting and separation to obtain vanadium-containing molten iron and titanium-containing slag.

[0040] This invention reduces pellet agglomeration during vertical shaft furnace smelting by separately pelletizing the slag conditioner (calcareous flux) typically used in the smelting process (step 40) and pre-adding it to the pre-reduction process (step 30) of the gas-based vertical shaft furnace. This ensures normal feeding and good permeability during the smelting of vanadium-titanium magnetite pellets in the gas-based vertical shaft furnace, guaranteeing stable and smooth operation of the furnace. Furthermore, after high-temperature reduction in the vertical shaft furnace, the mixed, shaped, and sintered calcareous flux pellets and vanadium-titanium magnetite oxide pellets are hot-charged into the electric furnace for direct electric furnace smelting. The calcareous pellets can simultaneously enter the deep molten pool along with the vanadium-titanium magnetite metallized pellets, avoiding the problems of difficulty in adding flux directly into the electric furnace and long mixing times.

[0041] Since the slag conditioner (calcium flux) has been added in advance, there is no need to add the corresponding flux again in step 40.

[0042] The specific process parameters for steps S20 and S30 are the same as those for steps S1 and S2 mentioned above, and will not be repeated here.

[0043] The specific embodiments of the present invention will be further illustrated below, but the specific embodiments of the present invention are not limited to the following embodiments.

[0044] Example 1:

[0045] Shaped calcareous pellets were made from quicklime (with a calcium oxide content >97%), controlled at a diameter of 10-12.5 mm, and the compressive strength was measured to be 2378 N. Before addition, the vanadium-titanium pellets had a bonding index of 49.10 at 1100℃ and a reducing gas composition of H2:CO = 50%:50%. To control the basicity of the electric furnace slag at 0.4, 5.91% by mass of calcareous pellets were added. After addition, the bonding index of the pellets in the mixed furnace charge was measured to be 3.82, showing a significant decrease in bonding index.

[0046] Example 2:

[0047] Shaped calcareous pellets made from limestone (with a calcium oxide content >95%), controlled to a diameter of 5-10 mm, had a compressive strength of 2578 N. Before addition, at 1000℃ and with a reducing gas composition of H2:CO = 75%:25%, the blistering index of the vanadium-titanium pellets was 16.83. To control the basicity of the electric furnace slag at 1.1, 9.56% by mass of calcareous pellets were added. After addition, the blistering index of the pellets in the mixed furnace charge was measured to be 1.15, indicating that the pellets essentially did not blister.

Claims

1. A gas-based vertical shaft furnace-electric furnace smelting process for vanadium-titanium magnetite, characterized in that, Includes the following steps: Step 10: Prepare vanadium-titanium magnetite oxide pellets; Step 20: Prepare shaped sintered calcium flux pellets from raw materials that can be calcined to obtain calcium oxide and used as slag conditioners in the melting process. The shaped sintered calcium flux pellets are made from one or more of quicklime, hydrated lime, and limestone. The diameter of the shaped sintered calcium flux pellets is controlled at 5-15 mm, and the compressive strength is above 2000 N. Step 30: The shaped sintered calcium flux pellets prepared in Step 20 are uniformly mixed with the vanadium-titanium magnetite oxide pellets prepared in Step 10 and then loaded into a gas-based vertical shaft furnace. Reducing gas is introduced for pre-reduction to obtain vanadium-titanium magnetite metallized pellets and calcium flux pellets. The loaded shaped sintered calcium flux pellets reduce the contact between vanadium-titanium magnetite oxide pellets, thereby reducing pellet adhesion during vertical shaft furnace smelting. Step 40: The vanadium-titanium magnetite metallized pellets and calcium flux pellets obtained in Step 30 are hotly charged into an electric furnace for electric furnace melting and separation to obtain vanadium-containing molten iron and titanium-containing slag.

2. The gas-based vertical shaft furnace-electric furnace vanadium-titanium magnetite smelting process according to claim 1, characterized in that, In step 40, no flux needs to be added.

3. The gas-based vertical shaft furnace-electric furnace vanadium-titanium magnetite smelting process according to claim 1, characterized in that, In step 20, the compressive strength of the sintered calcium flux pellets is above 2500N.

4. The gas-based vertical shaft furnace-electric furnace vanadium-titanium magnetite smelting process according to claim 1, characterized in that, In step 30, the amount of calcium flux pellets added for shaping and sintering is determined according to the basicity required for the electric furnace melting.

5. The gas-based vertical shaft furnace-electric furnace vanadium-titanium magnetite smelting process according to claim 4, characterized in that, The basicity required for electric furnace melting is 0.2-1.

2.

6. The gas-based vertical shaft furnace-electric furnace vanadium-titanium magnetite smelting process according to claim 5, characterized in that, In step 30, the amount of calcium flux pellets added for shaping and sintering is between 2% and 10% by mass.

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