A type of pulverized fuel for blast furnace smelting of vanadium-titanium magnetite.

Abstract

This invention relates to the field of blast furnace smelting technology and discloses a pulverized coal injection fuel for blast furnace smelting of vanadium-titanium magnetite. The fuel is composed of the following coal blends by mass percentage: 50-55% anthracite, 30% bituminous coal, and 15-20% semi-coke. The anthracite has a fixed carbon content of 80.24%, an ash content of 12.44%, and a volatile matter content of 7.32%; the bituminous coal has a fixed carbon content of 61.48%, an ash content of 8.44%, and a volatile matter content of 30.08%; and the semi-coke has a fixed carbon content of 79.69%, an ash content of 11.17%, and a volatile matter content of 9.14%. The pulverized coal injection fuel provided by this invention exhibits good combustion performance, reduces the generation of unburned coal powder, inhibits the formation of Ti(C,N) particles, and ensures the stable and smooth operation of the blast furnace smelting of vanadium-titanium magnetite. It contains an optimally proportioned semi-coke blend, realizing the application of semi-coke as a pulverized coal injection fuel in blast furnaces for vanadium-titanium magnetite smelting.

Description

Technical Field

[0001] This invention relates to the field of blast furnace smelting technology, and specifically to a pulverized fuel for blast furnace smelting of vanadium-titanium magnetite. Background Technology

[0002] Pulverized coal, as one of the main fuels for blast furnace ironmaking, provides a continuous supply of heat to the blast furnace through stable and efficient combustion. The amount of pulverized coal injected into blast furnaces in my country has been steadily increasing, leading to a sharp rise in demand for bituminous and anthracite coal. To reduce the cost of pulverized coal injection, current technology involves adding non-coal-based materials to reduce reliance on bituminous and anthracite coal.

[0003] Semi-coke is a semi-coke product made from high-volatile, weakly caking or non-caking coal. It is produced through medium- and low-temperature dry distillation and carbonization to remove tar and most of the volatile matter. It is characterized by low sulfur content, low ash content, high gasification efficiency, good reactivity, and good combustion performance, making it a promising source of raw materials for blast furnace injection. Semi-coke has gained attention from steel companies due to its excellent performance, lower price compared to anthracite, and environmentally friendly characteristics, and is gradually becoming a preferred feedstock for blast furnace injection. Current research on semi-coke injection in blast furnaces mainly focuses on blast furnaces used for smelting ordinary ore (ordinary blast furnaces), and there are no reports specifically on blast furnaces used for smelting vanadium-titanium ore (vanadium-titanium blast furnaces).

[0004] Compared to ordinary blast furnaces, vanadium-titanium blast furnaces contain a large amount of TiO2 in their slag, which is easily over-reduced within the furnace, generating high-melting-point Ti(C,N) compounds. The generated Ti(C,N) particles drastically worsen the slag's fluidity, causing it to thicken or even become difficult to flow. Simultaneously, a large number of fine Ti(C,N) particles stabilize air bubbles, resulting in foamy slag, severely impacting the smooth operation of the blast furnace. Furthermore, it deteriorates the wettability of slag and iron, causing small iron beads to be carried away by the slag, making slag-iron separation difficult and increasing iron loss. Semi-coke, as an injection fuel, suffers from poor grindability and low combustion rate. When this "problematic fuel," semi-coke, encounters the "difficult ore," vanadium-titanium magnetite, the relatively low combustion rate of semi-coke produces more unburned coal powder (carbon) that enters the slag, intensifying the TiO2 reduction reaction and promoting the formation of more and more dispersed Ti(C,N). This dramatically increases the risk of slag "thickening," amplifying furnace condition problems many times over. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a pulverized coal injection fuel for vanadium-titanium magnetite blast furnace smelting, aiming to realize the application of semi-coke as pulverized coal injection fuel in vanadium-titanium magnetite smelting blast furnaces, and to maximize the proportion of semi-coke used in pulverized coal injection fuel while ensuring the stable and smooth operation of the blast furnace.

[0006] To achieve the above objectives, the present invention provides a pulverized coal injection fuel for blast furnace smelting of vanadium-titanium magnetite, the fuel being composed of the following coal blends by mass percentage: 50-55% anthracite, 30% bituminous coal, and 15-20% semi-coke; wherein the anthracite has a fixed carbon content of 80.24%, an ash content of 12.44%, and a volatile matter content of 7.32%; the bituminous coal has a fixed carbon content of 61.48%, an ash content of 8.44%, and a volatile matter content of 30.08%; and the semi-coke has a fixed carbon content of 79.69%, an ash content of 11.17%, and a volatile matter content of 9.14%.

[0007] Furthermore, the anthracite coal comprises the following elements by mass percentage: C 78.40%, H 3.26%, N 1.02%, and S 0.31%.

[0008] Furthermore, the bituminous coal comprises the following elements by mass percentage: C 75.12%, H 4.18%, N 0.78%, and S 0.27%.

[0009] Furthermore, the semi-coke comprises the following elements by mass percentage: 80.28% C, 2.19% H, 0.89% N, and 0.21% S.

[0010] Furthermore, the calorific value of the anthracite is 30397.66 kJ / kg, the calorific value of the bituminous coal is 27911.26 kJ / kg, and the calorific value of the semi-coke is 27697.78 kJ / kg.

[0011] Furthermore, the anthracite, bituminous coal, and semi-coke are crushed to the specified particle size and then injected into the blast furnace in proportion.

[0012] Furthermore, the particle size of the anthracite is 4-12 mm, the particle size of the bituminous coal is 6-25 mm, and the particle size of the semi-coke is 8-12 mm.

[0013] This invention systematically analyzes the injection performance of semi-coke and pulverized coal for blast furnaces, studies the influence of semi-coke on the combustion performance of mixed coal, conducts industrial tests on semi-coke injection in blast furnaces for vanadium-titanium ore smelting, explores the impact of introducing semi-coke into the mixed coal system on the operation of blast furnaces for vanadium-titanium ore smelting, obtains the optimal addition ratio of semi-coke under the premise of ensuring stable and smooth operation of the blast furnace, and realizes the application of semi-coke as injection fuel in blast furnaces for vanadium-titanium magnetite smelting.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The pulverized coal fuel provided by this invention has good combustion performance, reduces the amount of unburned coal powder generated, inhibits the formation of Ti(C,N) particles, and ensures the stable and smooth operation of blast furnace smelting vanadium-titanium magnetite. The pulverized coal fuel provided by this invention contains an optimal ratio of semi-coke, realizing the application of semi-coke as pulverized coal fuel in blast furnace smelting vanadium-titanium magnetite. Specific implementation methods To better understand the present invention, the present invention will be further described below with reference to the embodiments. However, the content of the present invention is not limited to the following embodiments. All changes or equivalent substitutions that do not depart from the concept of the present invention are included within the protection scope of the present invention.

[0015] The anthracite, bituminous coal, and semi-coke used in the following examples were all purchased through legitimate commercial channels. Their industrial and elemental analyses are shown in Table 1 below.

[0016] Table 1. Industrial and elemental analysis of anthracite, bituminous coal and semi-coke

[0017] Based on the analysis of the basic properties of the experimental raw materials (anthracite, bituminous coal and semi-coke) and the specific conditions of blast furnace smelting of vanadium-titanium magnetite, the coal blending scheme shown in Table 2 below was formulated.

[0018] Table 2. Coal Blending Scheme

[0019] The above coal blending schemes were applied to vanadium-titanium ore blast furnaces under the same conditions. The test results showed that when 30% bituminous coal was added, the blast furnace condition was better when the semi-coke addition ratio was 15-20%. However, further increasing the semi-coke injection ratio would lead to a deterioration of the blast furnace indicators.

[0020] Based on the comprehensive technical indicators of the vanadium-titanium blast furnace at the target enterprise, it was decided to initially incorporate 15% semi-coke into the mixed coal to replace anthracite in the initial industrial trial of semi-coke injection, exploring the impact of semi-coke injection on the core indicators and stability of the vanadium-titanium blast furnace. The experimental results showed that, compared to the baseline period, the ash content of the mixed coal decreased from 11.90% to 11.77% after semi-coke injection. A small portion of the ash residue from pulverized coal combustion rises with the gas flow and enters the upper part of the blast furnace or is discharged from the top, while the majority enters the slag, affecting its metallurgical properties. The decrease in mixed coal ash content after partial replacement of anthracite with semi-coke injection is mainly due to the lower ash content of semi-coke compared to anthracite. The sulfur load showed a decreasing trend after semi-coke injection, decreasing from 5.40 kg / t to 5.37 kg / t. This is likely due to the lower sulfur content of semi-coke, which reduces the sulfur content in the mixed coal, thus reducing the sulfur load entering the furnace.

[0021] In addition, relevant statistics were also compiled on the changes in more key blast furnace indicators before and after the injection of semi-coke into the vanadium-titanium blast furnace, as shown in Table 3 below. Overall, the operating status of the vanadium-titanium blast furnace fluctuated during the test but remained relatively stable. After the injection of semi-coke, the vanadium-titanium blast furnace was still able to maintain basically stable operation. This indicates that a low proportion of semi-coke injection has no significant impact on the stable operation of the vanadium-titanium blast furnace.

[0022] Table 3. Changes in key indicators of vanadium-titanium blast furnace between the baseline period and the testing period

[0023] The results show that after injecting a low proportion of semi-coke, the core indicators of the vanadium-titanium blast furnace, such as blast temperature, oxygen enrichment rate, and pressure difference, did not change significantly, and the blast furnace maintained stable operation. Compared with the baseline period, the average sulfur load of the blast furnace decreased by 0.03% and the average ash content decreased by 0.13% during the test period, resulting in reduced desulfurization costs.

[0024] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, any improvements and modifications made based on the core ideas of the present invention without departing from the spirit and scope of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A type of injection fuel for blast furnace smelting of vanadium-titanium magnetite, characterized in that: The fuel is composed of the following coal blends by mass percentage: 50-55% anthracite, 30% bituminous coal, and 15-20% semi-coke; wherein the anthracite has a fixed carbon content of 80.24%, an ash content of 12.44%, and a volatile matter content of 7.32%; the bituminous coal has a fixed carbon content of 61.48%, an ash content of 8.44%, and a volatile matter content of 30.08%; and the semi-coke has a fixed carbon content of 79.69%, an ash content of 11.17%, and a volatile matter content of 9.14%.

2. The fuel according to claim 1, characterized in that: The anthracite coal comprises the following elements by mass percentage: C 78.40%, H 3.26%, N 1.02%, and S 0.31%.

3. The fuel according to claim 1, characterized in that: The bituminous coal comprises the following elements by mass percentage: 75.12% C, 4.18% H, 0.78% N, and 0.27% S.

4. The fuel according to claim 1, characterized in that: The semi-coke comprises the following elements by mass percentage: 80.28% C, 2.19% H, 0.89% N, and 0.21% S.

5. The fuel according to claim 1, characterized in that: The calorific value of the anthracite is 30397.66 kJ / kg, the calorific value of the bituminous coal is 27911.26 kJ / kg, and the calorific value of the semi-coke is 27697.78 kJ / kg.

6. The fuel according to claim 1, characterized in that: The anthracite, bituminous coal, and semi-coke are crushed to the specified particle size and then injected into the blast furnace in proportion.

7. The fuel according to claim 6, characterized in that: The anthracite has a particle size of 4-12 mm, the bituminous coal has a particle size of 6-25 mm, and the semi-coke has a particle size of 8-12 mm.

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