Preparation method of sintered return ore cold-pressing block with high and low temperature reduction degradation index

Abstract

The invention provides a preparation method of a high-low temperature reduction degradation index sintered return ore cold-pressing block, and relates to the technical field of blast furnace ironmaking raw material preparation, and the preparation method comprises five steps of material preparation, material mixing, pressing, maintenance and drying. The high-alkalinity sintered return mine is used as a main raw material and matched with a modified binder, and the cold-pressed block is prepared through the steps of burdening, mixing, pressing and drying. The binder is composed of a component A and a component B). The cold pressing block prepared by the invention has good drop strength, relatively high compressive strength and relatively high low-temperature reduction degradation index. The high-alkalinity sintered return ore cold-pressing block is used for blast furnace ironmaking, and the adding proportion accounts for 0.5-30% of iron-containing furnace charge. Reasonable utilization of the sintering return mine is realized, the cost is reduced, the proportion of blast furnace clinker is increased, and the source of blast furnace raw materials is expanded.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking raw material preparation technology, and in particular to a method for preparing cold-pressed sintered return ore briquettes with high and low temperature reduction pulverization index. Background Technology

[0002] For a considerable period to come, sintered ore will remain the primary feedstock for blast furnaces in my country, and my country will continue to be the world's largest producer of sintered ore. Due to the fluid dynamics of the reduction reaction within the blast furnace, small-particle sintered ore (<5mm) is difficult to directly feed into the furnace as sintered return ore. The traditional high-energy-consuming re-firing process for sintered return ore urgently needs improvement. Developing low-energy-consuming sintered return ore utilization processes will significantly reduce carbon emissions from the sintering process, providing better support for the still-growing sintering industry and promoting the green and healthy development of steel enterprises. Cold-pressing sintered return ore into briquettes before blast furnace utilization is a process with fewer steps, no high-temperature processes, low energy consumption, low production costs, convenient transportation, low investment, short construction period, and environmental friendliness. Sintered return ore is clinker with stable composition, and the cold-pressed briquettes have uniform particle size, making them an ideal blast furnace feedstock. Cold-pressed sintered return ore briquettes not only avoid the re-firing of sintered return ore but also improve blast furnace operation and reduce the blast furnace fuel ratio by increasing the proportion of clinker.

[0003] Currently, the preparation of cold-pressed sintered ore briquettes faces the problem of a lack of suitable binders. Furthermore, it suffers from several drawbacks, including complex processes, introduction of large amounts of alkali metals, low utilization of sintered ore ore, and difficulty in achieving the required high-temperature strength for blast furnace smelting. Insufficient high-temperature strength is a key bottleneck restricting its large-scale industrial application. Therefore, there is an urgent need to develop a novel method for preparing cold-pressed briquettes to overcome the shortcomings of the aforementioned methods.

[0004] Chinese patent (CN120099281) discloses a composite binder for iron ore powder briquettes and its application. This invention requires modification of the water glass, which inevitably introduces alkali metals, increasing process complexity and generating waste liquid. The raw materials used include magnetite concentrate, which reduces the basicity of the cold-pressed briquettes, causing fluctuations in blast furnace conditions after feeding. Magnetite concentrate replaces 0-1mm sintered return ore, but the utilization rate of sintered return ore is only in the range of 47-62%. This invention requires screening of the sintered return ore, increasing the cost of industrial implementation. The high-temperature metallurgical properties of the cold-pressed briquettes are unknown, yet these properties are crucial for blast furnace ironmaking.

[0005] Chinese patent (CN118854054A) discloses a high-strength cold-pressed briquette made from recycled ore and its preparation method. The mixed iron ore used in this invention consists of 60% recycled ore, 30% high-silica powder, and 10% ball-milled iron particles. The recycled ore accounts for only 60%, and the high-silica powder and ball-milled iron particles reduce the basicity of the cold-pressed briquettes, causing fluctuations in blast furnace conditions and increasing slag volume. The binder contains 50-90% sodium silicate, which will introduce a large amount of alkali metals into the blast furnace, affecting normal smelting and its lifespan. The high-temperature metallurgical properties of the cold-pressed briquettes are unknown, but these properties are crucial for blast furnace ironmaking. For example, a lower low-temperature reduction pulverization index will worsen the permeability of the blast furnace burden, adversely affecting blast furnace smelting.

[0006] Chinese patent (CN118996116A) discloses a method for adjusting the binder ratio in the cold-pressing process of sintered return ore. This method requires first determining the proportion of different particle sizes in the sintered return ore, increasing the complexity of the process. Furthermore, in practice, even within the same batch of sintered return ore, particle size distribution differs between the top and bottom of the stockpile due to differences in gravity and friction caused by different particle sizes, making it difficult to accurately determine the proportion of different particle sizes. The binder in this invention contains 28% polyvinyl alcohol (PVA). PVA has a melting point around 230°C. The melting of a large amount of PVA can damage the structure of the cold-pressed ore, causing its high- and medium-temperature metallurgical properties to fail to meet furnace requirements. Therefore, this invention proposes a method for preparing cold-pressed sintered return ore with a high and low temperature reduction pulverization index to solve the problems existing in the prior art. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to propose a method for preparing cold-pressed sintered return ore briquettes with high and low temperature reduction pulverization index. The present invention solves the problems of lack of suitable binders, low utilization rate of return ore, and insufficient high-temperature strength in the prior art by optimizing the binder and process parameters.

[0008] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a method for preparing cold-pressed ore return briquettes with high and low temperature reduction pulverization index sintering, comprising the following steps:

[0009] Step 1: Weigh the raw materials according to the dry weight percentage. The raw materials consist of 91-96% sintered return ore and 4-9% binder, wherein the basicity of the sintered return ore is not less than 1.2.

[0010] Step 2: Mix the weighed sintered return ore and binder in the first stage. After mixing evenly, add water for the second stage of mixing. The total amount of water added accounts for 6-15% of the total dry weight of the sintered return ore and binder until a mixture with uniform moisture content is obtained.

[0011] Step 3: Using a briquetting machine, the mixture is pressed into wet, cold-pressed briquettes of a predetermined shape;

[0012] Step 4: Regularly maintain the moisture content of the wet cold-pressed green blocks;

[0013] Step 5: Place the cured wet cold-pressed block in a drying equipment and dry it at a temperature of 80-330℃ for 3-12 hours to obtain the finished cold-pressed block;

[0014] The performance indicators of the finished cold-pressed blocks must meet at least the following requirements: Under wet conditions before curing, the drop strength from 1 meter must be no less than 3 times; after curing, the room temperature compressive strength must be no less than 1800 N; the low-temperature reduction pulverization index (RDI+3.15) must be no less than 70%; the compressive strength after the low-temperature reduction pulverization index test must be ≥500 N; and the compressive strength after reduction at 900℃ must be ≥300 N. The utilization rate of sintered return ore is high, using 91~96% high-basicity (≥1.2) sintered return ore as raw material. There is no need to further refine the raw material particle size. A composite binder (component A and component B) is used to ensure that the cold-pressed blocks have excellent low-temperature and high-temperature strength. The cold-pressed blocks exhibit good drop strength (≥3 times), high compressive strength (≥1800 N), and high and low-temperature reduction pulverization index (≥70%) under wet conditions, with a compressive strength after reduction at 900℃ ≥300 N. This meets the requirements for low-temperature and high-temperature strength of the cold-pressed blocks for transportation and blast furnace smelting. The drying temperature is 80~330℃ and the drying time is 3~12h. Its advantage is that the drying temperature and drying time are within a wide range, which is conducive to the drying workshop to flexibly adjust the drying process and better control the production rhythm.

[0015] A further improvement is made in the following: In step one, the adhesive is a compound of component A and component B with different functions, wherein component A is selected from one or more organic adhesive materials including starch, methylcellulose, polyvinyl alcohol, polyacrylamide, molasses and biomass gum, and its addition amount accounts for 0.1% to 1.5% of the total dry weight of the raw materials;

[0016] Component B is selected from one or more inorganic binders, including calcium-based bentonite, hydrated lime, cement, metakaolin, lightly calcined magnesia, and dolomite powder, and its addition amount accounts for 3.9% to 7.5% of the total dry weight of the raw materials. It ensures that key indicators such as the low-temperature reduction pulverization index and compressive strength after the low-temperature reduction pulverization index test of the cold-pressed briquettes meet the requirements of blast furnace smelting, and the binder does not contain alkali metals.

[0017] A further improvement is made in step two, where the duration of the first mixing stage is 2–20 minutes, and the duration of the second mixing stage is 2–30 minutes. This ensures that the sintered return ore and binder are mixed evenly, reducing binder agglomeration.

[0018] A further improvement lies in the following: In step two, both the first and second stages of mixing are carried out in a mixing device with grinding capabilities, ensuring that 10%–90% of the particles by weight in the mixed material have a particle size of ≤3.5mm. The appearance of lumpy, agglomerated particles with a length, width, or diameter of ≥15mm in the mixed material is used as a visual indicator that the mixing uniformity has met the requirements and the mixing step can be terminated. The grinding function during the mixing process improves the particle size distribution of the cold-pressed briquette raw materials, controlling the particle size (10%–90% ≤3.5mm), resulting in higher strength in the cold-pressed briquette and easier reduction of smaller particles during reduction. The appearance of large, agglomerated particles (side length ≥15mm) is used as the termination indicator to ensure uniform mixing and good molding results.

[0019] A further improvement lies in the following: In step four, the curing is carried out through intermittent water spraying. Specifically, starting from the pressing and molding process, the cold-pressed block green is sprayed with water every 8-12 hours, with a total curing cycle of 7-30 days. The strength of the cold-pressed block continuously increases during the curing period.

[0020] A further improvement is made in step five, where the drying equipment is any one or a combination of several of the following: a microwave drying oven, an electric heating drying oven, and a gas-fired drying oven. A microwave drying oven allows the drying process to be completed in a shorter time, significantly improving production efficiency.

[0021] A further improvement is made in step five, where the finished cold-pressed briquettes can be directly used as iron-containing furnace charge in blast furnace ironmaking, with an addition ratio ranging from 0.5% to 30%. This expands the utilization pathways of sintered return ore, and the addition of cold-pressed briquettes to the furnace increases the proportion of clinker in blast furnace ironmaking, avoiding adverse effects on the permeability of the blast furnace charge column, and is conducive to the stable and smooth operation of the blast furnace ironmaking process.

[0022] Further improvements are made in that the finished cold-pressed block also has the following additional metallurgical properties: after the low-temperature reduction pulverization index standard test, its residual compressive strength is not less than 500N, and after simulated reduction at 900℃, its residual compressive strength is not less than 300N.

[0023] The beneficial effects of this invention are as follows: Through the synergistic effect of an innovative composite binder system and an optimized process flow, this invention successfully transforms high-basicity sintered return ore into high-performance ironmaking raw materials on a large scale, thereby achieving multiple goals of resource recycling, energy consumption reduction, and smelting enhancement. This scheme uses a high proportion of return ore (91-96%) as raw material and employs a special composite binder composed of organic and inorganic components, endowing the cold-pressed briquettes with excellent comprehensive metallurgical properties without introducing harmful alkali metals.

[0024] The cold-pressed briquettes prepared by this invention not only possess excellent wet strength to meet transportation requirements, but also exhibit a compressive strength exceeding 1800N after curing, a low-temperature reduction pulverization index (RDI+3.15) exceeding 70%, and high strength maintained even after reduction at 900℃. These combined ensure that the briquettes maintain structural integrity and good permeability even under the harsh high-temperature environment of a blast furnace. Simultaneously, the unique mixing process optimizes the raw material particle size through crushing, further enhancing the density and reducibility of the briquettes. This comprehensive solution fundamentally avoids the high energy consumption and emissions of traditional remelting processes, significantly reducing production costs, broadening the raw material sources for blast furnaces, and providing a practical technical path for stable blast furnace operation, reduced fuel ratios, and even the green and low-carbon transformation of the entire steel production process by increasing the proportion of clinker fed into the furnace. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0026] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0027] Example 1

[0028] according to Figure 1 As shown in the figure, this embodiment proposes a method for preparing cold-pressed ore cold-pressed blocks from high and low temperature reduction pulverization index sintering ore, including the following steps:

[0029] Step 1: Ingredients

[0030] Sintered return ore obtained from the blast furnace bottom screening of a steel enterprise was selected. Its main chemical composition was stable, and its basicity (CaO / SiO2 mass ratio) was tested to be 1.8. 95.0 kg of this sintered return ore (dry basis) was accurately weighed as the main iron-containing raw material. Simultaneously, 5.0 kg of composite binder (dry basis) was weighed. The composite binder consisted of: component A, industrial-grade corn starch, used in a quantity of 0.5 kg; and component B, commercially available metakaolin (Al2O3·2SiO2), used in a quantity of 4.5 kg. All raw materials in this step are based on dry weight.

[0031] Step 2: Mixing

[0032] The weighed sintered return ore and all the binder (starch and metakaolin) were fed into a roller mill mixer with powerful stirring and crushing functions. The equipment was started for the first stage of dry mixing, which lasted for 5 minutes to initially and uniformly disperse the solid powder. Then, 10.0 kg of clean industrial water was sprayed evenly into the mixer. The total amount of water added accounted for 10.0% of the total dry weight of the aforementioned sintered return ore and binder (100.0 kg). The second stage of wet mixing was then carried out for 10 minutes. During the mixing process, the crushing function of the equipment continued to operate, breaking down some of the coarser return ore particles. Process sampling and sieving analysis showed that approximately 30% (by weight) of the particles in the mixed material had a particle size of 3.5 mm or less. When the operator observed the appearance of multiple irregularly shaped, moist, blocky, and cohesive materials with a minimum side length of 15 mm in the mixture, it was determined that the mixing uniformity had met the process requirements, and the mixing operation was stopped.

[0033] Step 3: Suppression

[0034] The uniformly mixed, moist material is continuously fed into a double-roller briquetting machine via a conveyor belt. Under a set forming pressure, the material is pressed into an elliptical, wet, cold-pressed briquette. Typical briquette dimensions are approximately: major axis 50mm, minor axis 30mm, height 25mm, and a single briquette weight of approximately 40–45g.

[0035] Step 4: Maintenance

[0036] The pressed, wet cold-pressed blocks are transferred to a curing workshop with moisture-retaining conditions and neatly stacked. Starting from the completion of pressing, the stack of cold-pressed blocks is sprayed with water evenly every 10 hours using a spraying device to keep the surface moist and promote internal hydration. The entire curing process lasts for 14 days.

[0037] Step 5: Drying

[0038] The fully cured cold-pressed blocks are placed in trays and then into a microwave drying oven. The drying temperature is set to 150℃, and the drying time is 6 hours. Moderate air circulation is maintained during the drying process. After drying, the cold-pressed blocks are allowed to cool naturally to room temperature to obtain the final finished product: sintered return ore cold-pressed blocks.

[0039] The performance of the finished cold-pressed blocks prepared according to the above method was tested, and the results are as follows:

[0040] Wet 1-meter drop strength (before curing): Ten wet green billets were randomly selected and dropped freely from a height of 1 meter onto a 10mm thick steel plate. The number of consecutive drops each block endured until it broke was recorded. The average value of the 10 samples was calculated, and the result was 3 drops.

[0041] Compressive strength (after curing): Ten dried finished briquettes were randomly selected and loaded at a constant rate of 10 mm / min using a universal testing machine. The maximum pressure value at which the briquettes broke was recorded. The average value of the 10 samples was calculated, and the result was 2000 N.

[0042] Low-temperature reduction pulverization index (RDI+3.15): This measures the mass percentage of particles larger than 3.15 mm after reduction. The measured RDI+3.15 value was 75%.

[0043] Compressive strength after low-temperature reduction pulverization experiment: The residual briquettes with a particle size ≥3.15mm obtained after sieving in the above RDI experiment were tested for compressive strength, and the average value was 550 N.

[0044] Compressive strength after reduction at 900℃: The finished compressed block was placed in a reducing atmosphere (CO / N2 mixture) at 900℃ for isothermal reduction test, and then cooled to room temperature. Its compressive strength was tested, with an average value of 352 N.

[0045] Example 2

[0046] according to Figure 1 As shown in the figure, this embodiment proposes a method for preparing cold-pressed ore cold-pressed blocks from high and low temperature reduction pulverization index sintering ore, including the following steps:

[0047] Step 1: Ingredients

[0048] 95.0 kg of sintered return ore (dry basis) with an alkalinity of 2.0 was selected. The total amount of composite binder (dry basis) was 6.0 kg, and its specific composition was as follows: component A was polyvinyl alcohol, with a dosage of 0.5 kg, and component B was lightly calcined magnesium oxide (active MgO content ≥85%), with a dosage of 5.5 kg.

[0049] Step 2: Mixing

[0050] The dry mixing time is 7 minutes. Then, 8.08 kg of water (8.0% of the total dry weight of the raw materials, 101.0 kg) is added for wet mixing, which takes 12 minutes. The mixing equipment also has a crushing function, resulting in approximately 50% of the particles in the mixed material having a particle size ≤3.5 mm. The mixing process ends when large, cohesive pieces of material with a side length of not less than 17 mm appear.

[0051] Step 3: Suppression

[0052] The uniformly mixed, moist material is continuously fed into a double-roller briquetting machine via a conveyor belt. Under a set forming pressure, the material is pressed into an elliptical, wet, cold-pressed briquette. Typical briquette dimensions are approximately: major axis 50mm, minor axis 30mm, height 25mm, and a single briquette weight of approximately 40–45g.

[0053] Step 4: Maintenance

[0054] The pressed, wet cold-pressed green blocks are transferred to a curing workshop with moisture-retaining conditions and neatly stacked. Starting from the completion of pressing, the stack of cold-pressed blocks is sprayed with water evenly every 9 hours using a spraying device to keep the surface moist and promote internal hydration. The entire curing process lasts for 14 days.

[0055] Step 5: Drying

[0056] The fully cured cold-pressed blocks are placed on trays and then into an electrically heated drying oven. The drying temperature is set to 200℃, and the drying time is 4 hours. Moderate air circulation is maintained during the drying process. After drying, the cold-pressed blocks are allowed to cool naturally to room temperature, yielding the final finished product: sintered return ore cold-pressed blocks.

[0057] The performance of the finished cold-pressed blocks prepared according to the above method was tested, and the results are as follows:

[0058] Wet 1-meter drop strength (before curing): Ten wet green billets were randomly selected and dropped freely from a height of 1 meter onto a 10mm thick steel plate. The number of consecutive drops each block endured until it broke was recorded. The average value of the 10 samples was calculated, and the result was 3 drops.

[0059] Compressive strength (after curing): Ten dried finished briquettes were randomly selected and loaded at a constant rate of 10 mm / min using a universal testing machine. The maximum pressure value at which the briquettes broke was recorded. The average value of the 10 samples was calculated, and the result was 2100 N.

[0060] Low-temperature reduction pulverization index (RDI+3.15): This measures the mass percentage of particles larger than 3.15 mm after reduction. The measured RDI+3.15 value was 80%.

[0061] Compressive strength after low-temperature reduction pulverization experiment: The residual briquettes with a particle size ≥3.15mm obtained after sieving in the above RDI experiment were tested for compressive strength, and the average value was 600 N.

[0062] Compressive strength after reduction at 900℃: The finished compressed block was placed in a reducing atmosphere (CO / N2 mixture) at 900℃ for isothermal reduction test, and then cooled to room temperature. Its compressive strength was tested, with an average value of 403 N.

[0063] Comparative Example 1

[0064] This comparative example is used for comparison and illustration. When the binder system does not adopt the composite form of components A and B as described in this invention, but only a single organic component is used, the medium and high temperature metallurgical properties of the cold-pressed block are significantly deteriorated.

[0065] In this comparative example, the preparation method is basically the same as in Example 1. The key difference is that only component A is used as the binder, that is, 5.0 kg of corn starch is used as the sole binder, and component B (kaolinite) is not added at all. The water addition ratio is still 10% of the total dry weight.

[0066] After mixing, pressing, curing, and drying using the same process, the finished products were tested, and the results are as follows:

[0067] Wet drop strength from 1 meter: 3 times (equivalent to Example 1).

[0068] Compressive strength after curing: 1600 N (lower than 2000 N in Example 1).

[0069] Low-temperature reduction powdering index (RDI+3.15): 10% (far lower than 75% in Example 1, indicating severe low-temperature powdering).

[0070] Compressive strength after low-temperature reduction and pulverization test: 30 N (strength almost completely lost).

[0071] Compressive strength after reduction at 900℃: 10 N (extremely poor high-temperature structural strength).

[0072] Results analysis: Comparative example 1 shows that although a single organic binder can provide certain strength in both wet and dry states at room temperature, its bonding network is destroyed under the simulated medium-temperature reducing atmosphere of a blast furnace, resulting in severe pulverization of the briquettes and a sharp drop in strength, which completely fails to meet the stringent requirements of blast furnace smelting for high-temperature strength in the furnace charge.

[0073] Comparative Example 2

[0074] This comparative example is for illustrative purposes only. If the mixing process does not have a crushing function and the particle size distribution of the raw materials cannot be optimized, it will have an adverse effect on the performance of the cold-pressed briquettes, especially their low-temperature reduction and pulverization performance.

[0075] In this comparative example, the preparation method is basically the same as in Example 2, with the key difference being that the mixing equipment used is a common twin-shaft paddle mixer, which does not have a crushing function. Other parameters, such as mixing time, remain consistent with Example 2.

[0076] After preparation, performance tests were conducted, and the results are as follows:

[0077] Wet drop strength from 1 meter: 3 times.

[0078] Compressive strength after curing: 1700 N (lower than 2100 N in Example 2).

[0079] Low-temperature reduction pulverization index (RDI+3.15): 65% (significantly lower than 80% in Example 2).

[0080] Compressive strength after low-temperature reduction and pulverization test: 510 N.

[0081] Compressive strength after reduction at 900℃: 380 N.

[0082] Results analysis: Comparative Example 2 shows that the lack of crushing function in the mixing process leads to coarser raw material particle size, reduced density and contact area between particles, which affects the full utilization of the binder's effectiveness and ultimately reduces the overall strength and medium-temperature anti-pulverization (RDI) performance of the cold-pressed block.

[0083] By combining Examples 1 and 2, and Comparative Examples 1 and 2, it can be found that the present invention uses a composite binder of components A and B in a specific ratio, and combines it with a mixing process that has a crushing function, to prepare sintered return ore cold-pressed blocks that simultaneously possess excellent abnormal temperature strength, high and low temperature reduction pulverization index, and good high temperature post-strength. This effectively solves the key problems in the prior art, such as low return ore utilization rate and insufficient high temperature strength of cold-pressed blocks, and provides a reliable technical path for realizing large-scale, high-value-added resource utilization of sintered return ore.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its framework and scope of application, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing cold-pressed ore return briquettes with high and low temperature reduction pulverization index sintering, characterized in that: Includes the following steps: Step 1: Weigh the raw materials according to the dry weight percentage. The raw materials consist of 91-96% sintered return ore and 4-9% binder, wherein the basicity of the sintered return ore is not less than 1.

2. Step 2: Mix the weighed sintered return ore and binder in the first stage. After mixing evenly, add water for the second stage of mixing. The total amount of water added accounts for 6-15% of the total dry weight of the sintered return ore and binder until a mixture with uniform moisture content is obtained. Step 3: Using a briquetting machine, the mixture is pressed into wet, cold-pressed briquettes of a predetermined shape; Step 4: Regularly maintain the moisture content of the wet cold-pressed green blocks; Step 5: Place the cured wet cold-pressed block in a drying equipment and dry it at a temperature of 80-330℃ for 3-12 hours to obtain the finished cold-pressed block; Among them, the performance indicators of the finished cold-pressed blocks must meet at least the following: under wet conditions before curing, its drop strength of 1 meter is not less than 3 times; after curing, its room temperature compressive strength is not less than 1800N; and the low-temperature reduction and pulverization index, characterized by the RDI+3.15 index, is not less than 70%.

2. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step one, the adhesive is a compound of component A and component B with different functions. Component A is selected from one or more organic adhesive materials, including starch, methylcellulose, polyvinyl alcohol, polyacrylamide, molasses and biomass gum, and its addition amount accounts for 0.1% to 1.5% of the total dry weight of the raw materials. Component B is selected from one or more inorganic binders, including calcium-based bentonite, hydrated lime, cement, metakaolin, lightly calcined magnesium oxide and dolomite powder, and its addition amount accounts for 3.9 to 7.5% of the total dry weight of the raw materials.

3. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step two, the duration of the first mixing stage is 2 to 20 minutes, and the duration of the second mixing stage is 2 to 30 minutes.

4. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step two, both the first and second stages of mixing are carried out in a mixing device with grinding function, so that 10-90% of the particles by weight in the mixed material have a particle size of less than or equal to 3.5 mm. The appearance of blocky agglomerates with a length, width, or diameter of not less than 15 mm in the mixed material is used as a visual indicator to determine that the mixing uniformity has met the requirements and the mixing step can be ended.

5. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step four, the curing is intermittent water spraying curing. Specifically, starting from the pressing and molding, the cold-pressed green block is sprayed with water once every 8 to 12 hours, and the total curing cycle is 7 to 30 days.

6. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step five, the drying equipment is any one or a combination of several of the following: microwave drying oven, electric heating drying oven, and gas drying oven.

7. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: In step five, the finished cold-pressed briquettes can be directly used as iron-containing furnace charge in blast furnace ironmaking, with a mixing ratio ranging from 0.5% to 30%.

8. The method for preparing high and low temperature reduction pulverization index sintered return ore cold-pressed blocks according to claim 1, characterized in that: The finished cold-pressed block also has the following additional metallurgical properties: after the low-temperature reduction pulverization index standard test, its residual compressive strength is not less than 500N, and after simulated reduction at 900℃, its residual compressive strength is not less than 300N.

Images