A furnace charge structure to improve the softening and melting properties of high-chromium vanadium-titanium magnetite.

Abstract

This invention relates to a furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite. The furnace charge structure for high-chromium vanadium-titanium magnetite includes a global cluster structure and a high-proportion pellet structure. When the furnace charge structure is a global cluster structure, it includes 25%–35% acidic pellets and 65%–75% fluxing pellets. When the furnace charge structure is a high-proportion pellet structure, it includes 25%–35% high-basicity sinter, 25%–35% acidic pellets, and 35%–45% fluxing pellets; where percentages are by mass. By adjusting the basicity of the fluxing pellets and the proportion of 58 iron concentrate, the furnace charge structure optimization based on the softening-melting performance characterization is achieved while ensuring the overall basicity of the blast furnace charge and the proportion of high-chromium vanadium-titanium magnetite.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, and in particular to a furnace charge structure that improves the softening and melting properties of high-chromium vanadium-titanium magnetite. Background Technology

[0002] Blast furnaces are the most widely used and highest-volume ironmaking reactors worldwide. Softening-melting properties are crucial metallurgical indicators of blast furnace feedstock, directly impacting furnace conditions and stable operation. Sintered ore and pellets are currently the most widely used blast furnace feedstocks. High-basicity sintered ore is the most widely used blast furnace feedstock in my country, accounting for up to 70%. However, problems such as high pollution and carbon dioxide emissions from the sintering process, and poor reduction and pulverization performance of sintered ore, have not been effectively resolved. In the blast furnace raw material production process, sintering has the highest proportion of pollutant emissions: dust accounts for 35.4%, SO2 for 67%, and NO for [missing information]. x It accounts for 51.7%. However, the pollutant emissions from the pelletizing process are far lower than those from the sintering process: dust accounts for 5.2%, which is 1 / 7 of that from sintering; SO2 accounts for 20.1%, which is 1 / 3 of that from sintering; NO... x It accounts for 10.4%, which is 1 / 5 of the sintering process.

[0003] Compared to sinter, pellets have a more uniform particle size, higher compressive strength, and better reduction and pulverization properties. Furthermore, with advancements in grinding and beneficiation technology, finer-grained concentrates are more suitable for pelletizing processes. Compared to sintering, pellet production generates less pollution and consumes less energy, contributing to low-carbon goals at the blast furnace feed level. Increasing pellet production capacity and thus its proportion in the blast furnace feed is more conducive to smooth adaptation to the beneficiation-smelting process and is also an effective means to improve blast furnace operating parameters and ensure smooth charge flow. In existing technologies, the charge structure is typically composed of high-basicity sinter and acidic pellets, which have poor softening and melting properties. Therefore, a charge structure to improve the softening and melting properties of high-chromium vanadium-titanium magnetite is proposed. Summary of the Invention

[0004] (I) Technical Solution

[0005] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0006] This invention proposes a furnace charge structure to improve the softening and melting properties of high-chromium vanadium-titanium magnetite. The furnace charge structure for high-chromium vanadium-titanium magnetite includes a global pellet structure and a high-proportion pellet structure.

[0007] In the case of a global pellet structure for high-chromium vanadium-titanium magnetite, the charge structure includes 25%–35% acidic pellets and 65%–75% fluxing pellets.

[0008] When the furnace charge structure of high-chromium vanadium-titanium magnetite is a high proportion of pellet structure, the furnace charge structure includes 25% to 35% high basicity sinter, 25% to 35% acidic pellets and 35% to 45% fluxing pellets.

[0009] The percentage represents the mass percentage.

[0010] Optionally, the raw materials for acidic pellets include high-chromium vanadium-titanium magnetite and binders;

[0011] The raw materials for flux-type pellets include high-chromium vanadium-titanium magnetite, 58 iron concentrate powder, binder, and limestone.

[0012] Optionally, high-chromium vanadium-titanium magnetite and 58 iron concentrate powder are used as iron-containing raw materials;

[0013] Flux-containing pellets include:

[0014] High-chromium vanadium-titanium magnetite accounts for 50-70% of the iron-bearing raw materials, 58 iron concentrate powder accounts for 50-30% of the iron-bearing raw materials, limestone accounts for 13-22% of the flux-containing pellets, and binder accounts for 2% of the flux-containing pellets. The percentages are by mass.

[0015] Optionally, high-chromium vanadium-titanium magnetite raw materials include:

[0016] 50–52% TFe, 25–27% FeO, 4.5–6.5% SiO2, 0.6–1.2% CaO, 2–3.5% Al2O3, 3–4% MgO, 11–13% TiO2 and 0.8–1.5% Cr2O3; where percentages are mass percentages.

[0017] Optionally, 58 iron concentrate powder includes:

[0018] 57.5-58.5% TFe, 17-18% FeO, 7-8% SiO2, 1-2% CaO, 2-3.5% Al2O3, and 1-2% MgO; where percentages are mass percentages.

[0019] Optionally, high-basicity sinter includes:

[0020] 49–51% TFe, 7–9% FeO, 5–6% SiO2, 10–11% CaO, 3–4% Al2O3, 2–3% MgO, and 7–8% TiO2, where the percentages are by mass.

[0021] Optionally, acidic pellets include:

[0022] 50-51% TFe, ≤0.5% FeO, 5-6% SiO2, 0.5-1.5% CaO, 3-4% Al2O3, 3-4% MgO, 11-12% TiO2, 0.8-1.5% Cr2O3, where percentages are mass percentages.

[0023] Optionally, the binder is bentonite, the basicity range of the fluxing pellets is 1.5 to 2.2, the compressive strength of the fluxing pellets is ≥3000 N / P, and the reduction expansion rate of the fluxing pellets is ≤20%.

[0024] Optionally, the basicity of the high-basicity sinter is 1.92, and the drum strength of the high-basicity sinter is ≥78.5%.

[0025] Optionally, the compressive strength of the acidic pellets is ≥3000 N / P, and the reduction expansion rate of the acidic pellets is ≤15%.

[0026] (II) Beneficial Effects

[0027] The beneficial effects of this invention are as follows: This invention provides a furnace charge structure that improves the softening and melting properties of high-chromium vanadium-titanium magnetite. By adjusting the basicity of the tempered fluxing pellets and the proportion of 58 iron concentrate powder, it optimizes the furnace charge structure based on softening-melting performance characteristics, achieving a high proportion of pellets and global pellets while maintaining the overall basicity and proportion of high-chromium vanadium-titanium magnetite in the blast furnace charge. This high-proportion / global pellet charge structure reduces pollution, energy consumption, and CO2 emissions from the ironmaking process by decreasing the proportion of sinter and reducing sinter production. Simultaneously, while maintaining the basicity of the blast furnace slag and the proportion of vanadium-titanium ore in the furnace, it achieves better softening-melting properties, ensuring stable blast furnace charge performance and smooth blast furnace operation, which is beneficial for the efficient smelting of high-chromium vanadium-titanium magnetite. Detailed Implementation

[0028] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below through specific embodiments.

[0029] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0030] In these embodiments, unless otherwise specified, all parts and percentages are expressed by mass. A “part by mass” refers to a basic unit of measurement representing the mass ratio of multiple components. One part can represent any unit mass, such as 1 g or 3.527 g. If we say that component A has a parts by mass and component B has b parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It should not be misunderstood that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts. “And / or” is used to indicate that one or both of the described situations may occur; for example, A and / or B includes (A and B) and (A or B).

[0031] This invention proposes a furnace charge structure to improve the softening and melting properties of high-chromium vanadium-titanium magnetite. The furnace charge structure for high-chromium vanadium-titanium magnetite includes a global cluster structure and a high-proportion pellet structure. When the furnace charge structure is a global cluster structure, it comprises 25%–35% acidic pellets and 65%–75% fluxing pellets. When the furnace charge structure is a high-proportion pellet structure, it comprises 25%–35% high-basicity sinter, 25%–35% acidic pellets, and 35%–45% fluxing pellets. All percentages are by mass.

[0032] The aforementioned high-chromium vanadium-titanium magnetite and the aforementioned 58 iron concentrate powder are iron-bearing raw materials; the aforementioned fluxing pellets include: high-chromium vanadium-titanium magnetite accounting for 50-70% of the iron-bearing raw materials, 58 iron concentrate powder accounting for 50-30% of the iron-bearing raw materials, limestone accounting for 13-22% of the fluxing pellets, and binder accounting for 2% of the fluxing pellets, wherein the percentages are by mass.

[0033] The aforementioned high-chromium vanadium-titanium magnetite raw material includes: 50–52% TFe, 25–27% FeO, 4.5–6.5% SiO2, 0.6–1.2% CaO, 2–3.5% Al2O3, 3–4% MgO, 11–13% TiO2, and 0.8–1.5% Cr2O3; where the percentages are by mass.

[0034] The binder is bentonite, the basicity of the flux-modified pellets is in the range of 1.5 to 2.2, the compressive strength of the flux-modified pellets is ≥3000 N / P, and the reduction expansion rate of the flux-modified pellets is ≤20%.

[0035] The aforementioned 58% iron concentrate powder comprises: 57.5-58.5% TFe, 17-18% FeO, 7-8% SiO2, 1-2% CaO, 2-3.5% Al2O3, and 1-2% MgO; wherein, the percentages are mass percentages.

[0036] The aforementioned high-basicity sinter includes: 49-51% TFe, 7-9% FeO, 5-6% SiO2, 10-11% CaO, 3-4% Al2O3, 2-3% MgO, and 7-8% TiO2, where the percentages are by mass.

[0037] The basicity of the above-mentioned high-basicity sinter is 1.92, and the drum strength of the above-mentioned high-basicity sinter is ≥78.5%.

[0038] The aforementioned acidic pellets include: 50-51% TFe, ≤0.5% FeO, 5-6% SiO2, 0.5-1.5% CaO, 3-4% Al2O3, 3-4% MgO, 11-12% TiO2, and 0.8-1.5% Cr2O3, where the percentages are by mass.

[0039] The compressive strength of the above-mentioned acidic pellets is ≥3000 N / P, and the reduction expansion rate of the above-mentioned acidic pellets is ≤15%.

[0040] Preparation of acidic ore pellets: High-chromium vanadium-titanium magnetite and binder are mixed and pelletized; the mixing and pelletizing regime is as follows: mixing time 5 min, pelletizing disc rotation speed 72 r / min, pelletizing time 40 min, and green pellet moisture content 8.5%;

[0041] Preparation of flux-modified pellets: High-chromium vanadium-titanium magnetite, 58 iron concentrate powder, binder and limestone are mixed and pelletized according to the scheme; the mixing and pelletizing regime is as follows: mixing time 10 min, pelletizing disc rotation speed 60 r / min, pelletizing time 60 min, and green pellet moisture content 8.0%;

[0042] Calcination of acidic and flux-treated pellets: Acidic and flux-treated pellets are oxidatively calcined to obtain cooked pellets; the calcination process is as follows:

[0043] During the preheating oxidation stage, the temperature is increased to 880-960℃ at a heating rate of 8-12℃ / min, and held for 8-15min.

[0044] During the heating stage, the temperature is increased from 880-960℃ to 1200-1280℃ at a heating rate of 3-7℃ / min, and held for 15-25 minutes.

[0045] During the cooling phase, the temperature is reduced to 350°C at a rate of 6–10°C / min, and then the product is air-cooled to room temperature.

[0046] The roasted flux pellets, acid pellets, and sinter were combined according to weight ratios to form a comprehensive furnace charge scheme. The weight percentages included: 0-30% high-basicity sinter, 40-70% flux pellets, and 0-30% acid pellets. The comprehensive furnace charges under each scheme were subjected to softening-melting experiments according to the national standard GB / T 34211-2017 "Determination of Softening and Melting Performance of Iron Ore under High-Temperature Load Reduction". The softening-melting performance of each charge combination was compared.

[0047] To better explain and facilitate understanding of the present invention, a detailed description of the invention will be provided through specific embodiments.

[0048] Table 1 shows the furnace charge structure schemes for the comparative examples and embodiments; Table 2 shows the metallurgical properties, softening-melting properties, for the comparative examples and embodiments.

[0049]

[0050] Table 1

[0051]

[0052]

[0053] Table 2

[0054] As shown in Table 2, Comparative Example 1 represents the actual furnace charge structure on site. The furnace charge structures of Comparative Examples 1 and 2, which consist of single flux pellets, exhibit poor softening-melting performance. As the proportion of acidic pellets and the basicity of flux pellets increase, the overall softening-melting performance of the furnace charge improves until the proportion of acidic pellets reaches 30%, at which point the quality of flux pellets fails to meet the requirements for furnace entry. Therefore, under the global pellet furnace charge structure, in Example 3, the furnace charge structure of 30% acidic pellets + 70% flux pellets exhibits the best softening-melting performance, specifically characterized by a lower and more downward-shifted softening-melting zone and good furnace charge permeability.

[0055] For example, in blast furnace production, return materials and solid waste (gas ash, active ash, and steel slag, etc.) need to be disposed of in the blast furnace process, and the sintering process is one of the best ways to handle these raw materials. Therefore, based on the on-site raw material and fuel conditions and a high-proportion pelletized charge structure, an optimal charge structure with sintered ore is given. With the increase of the proportion of high-basicity sintered ore, in Example 6, the charge structure of 30% high-basicity sintered ore + 30% acidic pellets + 40% fluxing pellets achieved better softening-melting performance.

[0056] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite, wherein the charge structure of the high-chromium vanadium-titanium magnetite is a global cluster structure, characterized in that: The furnace charge structure comprises 25%–35% acidic pellets and 65%–75% fluxing pellets; wherein, the percentages are by mass. The raw materials for the flux-forming pellets include high-chromium vanadium-titanium magnetite, 58 iron concentrate powder, binder, and limestone. The high-chromium vanadium-titanium magnetite accounts for 50-70% of the iron-containing raw materials, the 58 iron concentrate powder accounts for 50-30% of the iron-containing raw materials, the limestone accounts for 13-22% of the flux-forming pellets, and the binder accounts for 2% of the flux-forming pellets. All percentages are by mass. The high-chromium vanadium-titanium magnetite and the 58 iron concentrate powder are iron-containing raw materials. The basicity range of the flux-dependent pellets is 1.5 to 2.

2.

2. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 1, characterized in that: The raw materials for the acidic pellets include high-chromium vanadium-titanium magnetite and binders.

3. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 1, characterized in that: The high-chromium vanadium-titanium magnetite includes: 50–52% TFe, 25–27% FeO, 4.5–6.5% SiO2, 0.6–1.2% CaO, 2–3.5% Al2O3, 3–4% MgO, 11–13% TiO2 and 0.8–1.5% Cr2O3; where percentages are mass percentages.

4. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 1, characterized in that: The 58 iron concentrate powder comprises: 57.5-58.5% TFe, 17-18% FeO, 7-8% SiO2, 1-2% CaO, 2-3.5% Al2O3, and 1-2% MgO; where percentages are mass percentages.

5. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 2, characterized in that... The acidic pellets include: 50-51% TFe, ≤0.5% FeO, 5-6% SiO2, 0.5-1.5% CaO, 3-4% Al2O3, 3-4% MgO, 11-12% TiO2, 0.8-1.5% Cr2O3, where percentages are mass percentages.

6. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 1, characterized in that: The binder is bentonite, the compressive strength of the flux-modified pellets is ≥3000 N / P, and the reduction expansion rate of the flux-modified pellets is ≤20%.

7. The furnace charge structure for improving the softening and melting properties of high-chromium vanadium-titanium magnetite as described in claim 1, characterized in that: The compressive strength of the acidic pellets is ≥3000 N / P, and the reduction expansion rate of the acidic pellets is ≤15%.

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