A blast furnace smelting method based on cold-pressed iron scale pellets

Abstract

The present application relates to the field of blast furnace smelting technology, in particular to a blast furnace smelting method based on oxide skin cold-pressed pellets. The method comprises the following steps: mixing the crushed oxide skin with blast furnace dust and glutinous rice starch solution, and uniformly mixing; cold-pressing to obtain pellets with iron content of 68% to 70% and carbon content of less than 5%; adding the pellets with ore batch into the blast furnace and arranging in the middle region of the throat material surface; adjusting the coke batch through a formula according to the amount of pellets, simultaneously increasing the alkalinity, air temperature and oxygen enrichment rate, and adjusting the material distribution system to control the central airflow. The present application efficiently converts metallurgical solid waste into blast furnace raw materials, eliminates the sintering process, and significantly reduces production cost and energy consumption; through the supporting operation strategy, the blast furnace is stably and smoothly operated, the resource recycling and green smelting are realized, and the present application has outstanding economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of blast furnace smelting technology, specifically a blast furnace smelting method based on cold-pressed iron oxide pellets. Background Technology

[0002] Recycling waste resources in the steel industry is a key theme advocated in the industry today and a way for steel companies to reduce energy consumption and achieve sustainable development. Steel companies generate various smelting solid wastes (steel slag, iron oxide scale, sludge, dust collector ash, etc.) during production, all of which contain a large amount of recyclable resources. Processing these powdered solid wastes into cold-pressed briquettes of a certain strength for use as blast furnace feedstock or steelmaking cooling feedstock can turn waste into treasure, further reducing enterprise costs and protecting the environment, which has profound significance. Iron oxide scale and other powdered materials cannot be used directly in ironmaking and steelmaking; they require sintering and blast furnace processes. If powdered materials are briquetted using briquetting equipment and then directly supplied to the blast furnace without mixing and sintering, the costs required for mixing and sintering processes will be directly saved. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a blast furnace smelting method based on cold-pressed iron oxide pellets, which efficiently converts metallurgical solid waste into blast furnace raw materials, eliminates the sintering process, and reduces production costs. Furthermore, through a matching material distribution and operation control strategy, it ensures that the blast furnace operates stably and smoothly while digesting solid waste, thereby achieving resource recycling and green smelting.

[0004] To achieve the above objectives, the present invention employs the following technical solution: A blast furnace smelting method based on cold-pressed iron oxide pellets specifically includes the following steps: 1) Preparation of cold-pressed iron oxide scale pellets: After crushing the iron oxide scale, it is mixed with blast furnace dust and glutinous rice starch solution, and then cold-pressed by a pelletizing machine to form cold-pressed iron oxide scale pellets for steel rolling, which are ellipsoidal in shape; The iron oxide scale cold-pressed pellets are added as an additional raw material, without replacing the original ore raw material, and the amount added in each batch is less than 10t; 2) Cold-pressed iron oxide pellets: The cold-pressed iron oxide pellets obtained in step 1) are added to the blast furnace along with the ore batch and their flow is placed at the rear of the overall furnace charge flow, so that the cold-pressed iron oxide pellets are finally placed in the middle area of ​​the furnace throat charge surface. 3) Coke batch adjustment: Based on the amount of added iron oxide scale cold-pressed pellets, adjust the coke batch according to the formula △J=(K×M×TFe)-[(M×C) / 0.85]; Where: △J is the coke batch adjustment amount, in kg; K is the coke ratio fed into the furnace, in kg / t; M is the mass of cold-pressed iron oxide pellets, in tons; TFe represents the iron content by weight in cold-pressed iron oxide pellets, % . C represents the carbon content (by weight) of the cold-pressed iron oxide pellets, in percentages (%). 4) Basicity adjustment: Adjust the basicity of the raw materials fed into the furnace according to the amount of cold-pressed iron oxide pellets added to stabilize the basicity of the final slag; 5) Furnace condition adjustment: Based on the amount of cold-pressed iron oxide pellets added, increase the blast furnace blast temperature and oxygen enrichment rate to cope with the increase in direct reduction degree in the furnace and the change in hearth heat load; 6) Adjustment of the ore distribution system: reduce the proportion of central coke by 1% to 2% or shift the overall ore distribution angle inward by 0.5° to 1°.

[0005] Further, in step 1), the chemical composition of the cold-pressed iron oxide pellets, by weight percentage, includes: TFe: 68%~70%, C<5%, CaO<0.5%, Al2O3<0.3%, and moisture<5%.

[0006] Further, in step 4), the specific method of adjusting the basicity is as follows: when the amount of each batch of cold-pressed iron oxide pellets added is less than 5t, the basicity of the furnace feed will be increased by 0.01; when the amount of each batch of cold-pressed iron oxide pellets added is less than 10t, the basicity of the furnace feed will be increased by 0.02.

[0007] Further, in step 5), the specific method of adjusting the furnace condition is as follows: when the amount of each batch of cold-pressed iron oxide scale pellets added is less than 5t, the blast furnace blast temperature is increased by 5~10℃ and the oxygen enrichment rate is increased by 0.05%~0.1%; when the amount of each batch of cold-pressed iron oxide scale pellets added is less than 10t, the blast furnace blast temperature is increased by 10~15℃ and the oxygen enrichment rate is increased by 0.1%~0.3%.

[0008] The blast furnace smelting method based on cold-pressed iron oxide scale pellets provided by this invention has the following significant advantages compared with the prior art: 1. Significantly efficient resource utilization and cost savings: This invention directly uses solid waste such as iron oxide scale and blast furnace gravity dust generated during steel plant production as raw materials. Through cold pressing technology, these materials are processed into iron-carbon pellets and returned to the blast furnace, achieving "on-site digestion" and resource recycling of steel plant solid waste. This method eliminates the necessary mixing and sintering processes in traditional methods, directly saving significant amounts of fuel and electricity consumption, as well as equipment operation and maintenance costs during sintering, thus significantly reducing production costs at the source.

[0009] 2. Optimize blast furnace burden structure and reduce smelting energy consumption: The cold-pressed pellets prepared by this invention have a high iron content (TFe 68%~70%) and contain a certain amount of carbon (C<5%), making them a high-quality "iron-carbon composite burden". After being added to the blast furnace, the carbon in the pellets can act as an internal reducing agent in the furnace, participating in the direct reduction reaction, thereby effectively reducing the blast furnace coke ratio, reducing the consumption of external fuel, and achieving energy saving and consumption reduction in the smelting process.

[0010] 3. Targeted Operating Processes Ensure Stable and Smooth Blast Furnace Operation: This invention does not simply involve adding pellets to the blast furnace, but rather employs a complete set of refined operating processes. By distributing the pellets in the middle area of ​​the furnace throat burden surface, a stable gas flow distribution is ensured; the established coke batch adjustment formula accurately calculates the change in coke quantity required due to pellet addition, guaranteeing stable furnace temperature; and the accompanying basicity adjustment and furnace condition adjustment strategies effectively offset the negative impacts of reduced final slag basicity and increased hearth heat load caused by pellet addition. These measures work together to ensure the long-term stable and smooth operation of the blast furnace while processing solid waste, without disrupting the blast furnace operating procedures.

[0011] 4. Significant environmental benefits: The pelletizing process directly avoids the highly polluting pelletizing and sintering steps in traditional processing. As it is a cold-pressing physical process, the entire process produces almost no CO2 or NO. x Pollutants such as SO2 are eliminated, and the binder's main component is modified starch, which is carbon-neutral like biomass. Therefore, the briquetting product has high environmental protection attributes. It aligns with the green, low-carbon, and sustainable development direction of the steel industry, and has significant environmental and social benefits.

[0012] 5. Simple process, convenient implementation, and high economic benefits: The cold-pressed pellet production process described in this invention has a short flow, low equipment investment, no need for high-temperature sintering, and extremely low energy consumption. The entire method can be directly embedded into the existing blast furnace production process without large-scale modification of the main equipment. It has the advantages of low investment, quick results, and significant economic benefits, providing a practical and feasible technical path for steel plants to reduce costs, increase efficiency, and achieve zero solid waste output. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0014] This invention discloses a blast furnace smelting method based on cold-pressed iron oxide pellets. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0015] The complete process flow of the blast furnace smelting method based on cold-pressed iron oxide pellets of the present invention is as follows: Figure 1 As shown. The core of the method lies in adding cold-pressed iron oxide scale pellets of a specific composition as an additional raw material to the blast furnace, and ensuring the stable and smooth operation of the blast furnace in processing this solid waste resource through a set of synergistic control strategies. The synergistic control strategies include at least specific charge distribution control, precise coke batch adjustment, and corresponding basicity and furnace condition adjustments.

[0016] The following are several specific embodiments of the present invention: Example 1: Low-load production (pellet addition rate ~3t / batch) This embodiment provides a blast furnace smelting method based on cold-pressed iron oxide pellets for stable production when the amount of pellets added is low.

[0017] Pellet preparation: After crushing the iron oxide scale from steel rolling, blast furnace dust and glutinous rice starch solution are added and mixed evenly. The mixture is then cold-pressed into pellets using a pelletizing machine. The chemical composition of the pellets, by weight percentage, includes: TFe: 69%, CaO: 0.4%, Al2O3: 0.25%, C: 4.2%, Moisture: 4%.

[0018] Pellet addition: The prepared cold-pressed iron oxide scale pellets are added to the blast furnace along with the ore batch as an additional raw material, without replacing the original ore raw material. In this embodiment, the amount added per batch is 3t.

[0019] Material distribution control: By adjusting the material distributor, the flow of the cold-pressed iron oxide pellets is distributed in the middle of the overall furnace charge flow, ensuring that after passing through the intermediate hopper, main belt, and upper and lower hoppers and being distributed into the furnace, most of it can be distributed in the middle area of ​​the furnace throat material surface.

[0020] Coke batch adjustment: Adjust the coke batch size based on the amount of pellets added. Set the current blast furnace coke ratio K = 360 kg / t, pellet mass M = 3t, pellet iron content TFe = 69%, and carbon content C = 4.2%.

[0021] Calculate the coke batch adjustment amount using the formula: △J = (360 × 3 × 69%) - [(3 × 4.2%) / 0.85]; △J = (360 × 3 × 0.69) - [(3 × 0.042) / 0.85]; △J=745.2-148.23=596.97kg.

[0022] Calculations show that approximately 596.97 kg / batch of coke needs to be added due to the addition of pellets.

[0023] Basicity adjustment: Since the amount of pellets added in each batch is less than 5t, the basicity (R2) of the raw materials fed into the furnace will be increased by 0.01 to stabilize the basicity of the final slag.

[0024] Furnace condition adjustment: Since the amount of pellets added in each batch is less than 5t, the blast furnace blast temperature will be increased by 8℃ and the oxygen enrichment rate will be increased by 0.08% to cope with the increase in direct reduction degree in the furnace and the change in hearth heat load.

[0025] Adjustment of the feeding system: Based on the phenomenon that the central airflow develops and the gas utilization rate decreases after adding iron oxide scale and cold-pressing pellets, the proportion of central coke is reduced by 1.5%.

[0026] Example 2: Medium-load production (pellet addition rate ~6t / batch) This embodiment provides a blast furnace smelting method based on cold-pressed iron oxide pellets for stable production when the pellet addition amount is moderate.

[0027] Pellet preparation: (Same as Example 1, with slight adjustments to the composition: TFe: 68.5%, C: 4.5%, other components are the same as in Example 1).

[0028] Pellet addition: (Same as in Example 1). In this example, the amount added per batch is 6t.

[0029] Fabric control: (Same as Example 1).

[0030] Coke batch adjustment: set K=360kg / t, M=6t, TFe=68.5%, C=4.5%.

[0031] △J = (360 × 6 × 68.5%) - [(6 × 4.5%) / 0.85]; △J = (360 × 6 × 0.685) - [(6 × 0.045) / 0.85]; △J = 1479.6 - 317.65; △J=1161.95kg.

[0032] Calculations show that approximately 1161.95 kg / batch of coke needs to be replenished.

[0033] Basicity adjustment: Since the amount of pellets added in each batch is between 5t and 10t, the basicity (R2) of the raw materials fed into the furnace will be increased by 0.02 to stabilize the basicity of the final slag.

[0034] Blast furnace condition adjustment: Since the amount of pellets added in each batch is between 5t and 10t, the blast furnace blast temperature will be increased by 12℃ and the oxygen enrichment rate will be increased by 0.2% to cope with the changes in furnace condition.

[0035] Adjustment of the ore distribution system: Based on the phenomenon that the central airflow develops and the gas utilization rate decreases after adding iron oxide scale and cold-pressing pellets, the ore distribution angle is shifted inward by 0.5° to 1°.

[0036] Example 3: High-load production (pellet addition rate ~8t / batch) This embodiment provides a blast furnace smelting method based on cold-pressed iron oxide pellets for stable production when the pellet addition amount is high.

[0037] Pellet preparation: After crushing the iron oxide scale from the rolled steel, blast furnace dust and glutinous rice starch solution are added and mixed evenly. The mixture is then cold-pressed into pellets using a pelletizing machine. The chemical composition of the pellets, by weight percentage, includes: TFe 70%, CaO content <0.5%, Al2O3 <0.3%, C content 4.8%, and moisture content <5%.

[0038] Pellet addition: The prepared cold-pressed iron oxide scale pellets are added to the blast furnace along with the ore batch as an additional raw material, without replacing the original ore raw material. In this embodiment, the amount added per batch is 8t.

[0039] Material distribution control: By adjusting the material distributor, the flow of cold-pressed iron oxide pellets is distributed in the middle of the overall furnace charge flow, ensuring that after passing through the intermediate hopper, main belt, and upper and lower hoppers and being distributed into the furnace, most of the cold-pressed pellets flow is in the middle area of ​​the furnace throat charge surface.

[0040] Coke batch adjustment: Adjust the coke batch size based on the amount of pellets added. Set the current blast furnace coke ratio K = 360 kg / t, pellet mass M = 8t, pellet iron content TFe = 70%, and carbon content C = 4.8%. Calculate using the formula: △J = (360 × 8 × 70%) - [(8 × 4.8%) / 0.85]; △J=2016-451.76; △J=1564.24kg.

[0041] Calculations show that approximately 1564.24 kg / batch of coke needs to be replenished.

[0042] Basicity adjustment: Since the amount of pellets added in each batch is less than 10t, the basicity (R2) of the raw materials fed into the furnace will be increased by 0.02 to stabilize the basicity of the final slag.

[0043] Blast furnace condition adjustment: Increase the blast furnace blast temperature by 12°C and increase the oxygen enrichment rate by 0.2% to cope with the increase in direct reduction in the furnace and the change in hearth heat load.

[0044] Adjustment of the ore distribution system: Based on the phenomenon that the central airflow develops and the gas utilization rate decreases after adding iron oxide scale and cold-pressing pellets, the ore distribution angle is shifted inward by 0.5° to 1°.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A blast furnace smelting method based on cold-pressed iron oxide scale pellets, characterized in that, Specifically, the following steps are included: 1) Preparation of cold-pressed iron oxide scale pellets: After crushing the iron oxide scale, it is mixed with blast furnace dust and glutinous rice starch solution, and then cold-pressed by a pelletizing machine to form cold-pressed iron oxide scale pellets for steel rolling, which are ellipsoidal in shape; The iron oxide scale cold-pressed pellets are added as an additional raw material, without replacing the original ore raw material, and the amount added in each batch is less than 10t; 2) Cold-pressed iron oxide pellets: The cold-pressed iron oxide pellets obtained in step 1) are added to the blast furnace along with the ore batch and their flow is placed at the rear of the overall furnace charge flow, so that the cold-pressed iron oxide pellets are finally placed in the middle area of ​​the furnace throat charge surface. 3) Coke batch adjustment: Based on the amount of added iron oxide scale cold-pressed pellets, adjust the coke batch according to the formula △J=(K×M×TFe)-[(M×C) / 0.85]; Where: △J is the coke batch adjustment amount, in kg; K is the coke ratio fed into the furnace, in kg / t; M is the mass of cold-pressed iron oxide pellets, in tons; TFe represents the iron content by weight in cold-pressed iron oxide pellets, % . C represents the carbon content (by weight) of the cold-pressed iron oxide pellets, in percentages (%). 4) Basicity adjustment: Adjust the basicity of the raw materials fed into the furnace according to the amount of cold-pressed iron oxide pellets added to stabilize the basicity of the final slag; 5) Furnace condition adjustment: Based on the amount of cold-pressed iron oxide pellets added, increase the blast furnace blast temperature and oxygen enrichment rate to cope with the increase in direct reduction degree in the furnace and the change in hearth heat load; 6) Adjustment of the ore distribution system: reduce the proportion of central coke by 1% to 2% or shift the overall ore distribution angle inward by 0.5° to 1°.

2. The blast furnace smelting method based on cold-pressed iron oxide scale pellets according to claim 1, characterized in that, In step 1), the chemical composition of the cold-pressed iron oxide pellets, by weight percentage, includes: TFe: 68%~70%, C<5%, CaO<0.5%, Al2O3<0.3%, and moisture<5%.

3. The blast furnace smelting method based on cold-pressed iron oxide pellets according to claim 1, characterized in that, In step 4), the specific method for adjusting the basicity is as follows: when the amount of cold-pressed iron oxide pellets added in each batch is less than 5t, the basicity of the feed furnace will be increased by 0.01; when the amount of cold-pressed iron oxide pellets added in each batch is less than 10t, the basicity of the feed furnace will be increased by 0.

02.

4. The blast furnace smelting method based on cold-pressed iron oxide scale pellets according to claim 1, characterized in that, In step 5), the specific method for adjusting the furnace condition is as follows: when the amount of each batch of cold-pressed iron oxide scale pellets added is less than 5t, the blast furnace blast temperature is increased by 5~10℃ and the oxygen enrichment rate is increased by 0.05%~0.1%; when the amount of each batch of cold-pressed iron oxide scale pellets added is less than 10t, the blast furnace blast temperature is increased by 10~15℃ and the oxygen enrichment rate is increased by 0.1%~0.3%.

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