Method for comprehensive treatment of red mud by blast furnace process

Abstract

This invention relates to the field of red mud treatment technology, specifically disclosing a method for comprehensive treatment of red mud using a blast furnace process. The method includes: mixing red mud, manganese ore powder, binder, and anthracite, and pressing them into carbon-containing raw material pellets; sintering the carbon-containing raw material pellets, then crushing, screening, and granulating them to obtain carbon-containing clinker pellets; mixing the carbon-containing clinker pellets, flux, and coke, and then feeding them into a blast furnace for reduction smelting at 1200-1350℃; followed by slag-iron separation to obtain manganese-rich slag and pig iron. This invention, by mixing red mud and manganese ore powder to prepare carbon-containing pellets and then smelting them in a blast furnace, utilizes the difference in reduction potential between iron and manganese at different temperatures for selective reduction. This allows iron to be preferentially reduced into the metallic phase, while manganese remains in the slag phase as MnO. This achieves simultaneous and efficient recovery of iron resources from red mud and manganese resources from manganese ore, completely solving the problem of traditional processes only extracting a single element (iron) and causing secondary pollution in the tailings, significantly improving the comprehensive utilization rate of resources.

Description

Technical Field

[0001] This invention relates to the field of red mud treatment technology, and in particular to a method for the comprehensive treatment of red mud using a blast furnace method. Background Technology

[0002] Red mud is a solid waste residue discharged during the production of alumina from bauxite. It gets its name from its reddish-brown color due to its high hematite content. Red mud is classified as Class II general industrial solid waste, characterized by strong alkalinity, high salinity, small particle size, high bulk density, and complex composition. According to statistics, by 2025, the cumulative stockpile of red mud in China exceeded 1.6 billion tons. The large-scale stockpiling of red mud not only occupies significant land resources but also easily causes environmental pollution and safety hazards. The highly alkaline chemicals and heavy metal ions in red mud can leach into the soil and groundwater, leading to groundwater pollution and other ecological and environmental safety issues. Furthermore, the fine particles of red mud easily generate dust during windy weather, threatening the atmospheric environment and the health of surrounding residents. Therefore, the comprehensive utilization of red mud is of great significance for protecting the ecological environment and improving the comprehensive utilization level of industrial resources.

[0003] Although red mud is industrial solid waste, it is also an important resource. Its main chemical components are ferrous oxide, alumina, and silicon dioxide, with a high iron content. It also contains rare elements such as gallium and scandium, all of which have high recycling value. Currently, the comprehensive utilization of red mud mainly focuses on three aspects: the recovery and extraction of valuable metals, the preparation of building materials, and roadbed filling materials. Regarding iron ore beneficiation from red mud, my country's iron ore beneficiation volume reached over 9.7 million tons in 2024, accounting for more than 70% of the total utilization. In the building materials sector, red mud can be used to prepare cement, non-fired bricks, and microcrystalline glass. However, my country's current comprehensive utilization rate of red mud is only about 12%, and most technologies still face cost and process bottlenecks, with the long-term storage problem remaining unresolved. Specifically, although red mud has a high iron oxide content, the iron minerals are extremely fine-grained and closely coexist with gangue minerals such as silicates, making efficient separation difficult with traditional magnetic separation processes. Direct reduction methods are energy-intensive, limiting their industrial application and hindering large-scale promotion. Furthermore, current domestic and international methods for the comprehensive utilization of red mud mainly focus on extracting valuable elements such as iron and aluminum. The associated useless minerals are discarded, continuing to pollute the environment. Chinese patent application CN 112251601 A discloses a method for iron recovery from red mud enhanced by manganese minerals. This method involves mixing red mud with manganese minerals and then performing reduction roasting to reduce the non-magnetic iron oxide in the red mud to strongly magnetic magnetite. Metallic iron powder is then obtained through grinding and magnetic separation. However, this method can only recover iron resources; manganese minerals are mainly used as additives, failing to achieve simultaneous and efficient recovery of manganese resources. Moreover, the tailings after iron extraction still require treatment, resulting in low resource utilization and potential secondary pollution. Summary of the Invention

[0004] To address the problems of difficulty in separating valuable metals from red mud and low comprehensive utilization rate in existing technologies, which easily lead to secondary pollution, this invention provides a method for the comprehensive treatment of red mud using a blast furnace. The method involves mixing red mud with manganese ore and other materials, burning it, and then selectively reducing and smelting it in a blast furnace to achieve efficient separation and comprehensive recovery of multiple metals such as iron and manganese. The specific technical solution is as follows: A method for comprehensive treatment of red mud using the blast furnace process includes the following steps: (1) Red mud, manganese ore powder, binder and anthracite are mixed and stirred, wherein the mass ratio of red mud to manganese ore powder is 30~50:50~70, and then pressed into carbon-containing raw material pellets; (2) The carbon-containing raw material pellets obtained in step (1) are sintered, then crushed, screened and sized to obtain sintered carbon-containing clinker pellets; (3) The carbon clinker pellets, flux and coke obtained in step (2) are mixed and then put into the blast furnace for reduction smelting at 1200~1350℃. Then the slag and iron are separated to obtain manganese-rich slag and pig iron.

[0005] The technical solution of this invention, without affecting the quality of manganese-rich slag, involves mixing an appropriate amount of red mud with manganese ore, coal, and other raw materials to produce carbon-containing manganese and aluminum ore pellets. The pellets are then rationally proportioned with flux and coke and fed into a blast furnace for batch smelting. In the blast furnace, selective reduction smelting is performed using the difference in reduction temperatures between iron and manganese, achieving effective extraction of iron resources from the red mud and enrichment of manganese resources in the slag. This avoids the secondary waste of tailings after iron extraction. The manganese-rich slag can be used as a main raw material for producing manganese alloys or as an indispensable deoxidizer and alloying agent in steelmaking, significantly improving the comprehensive utilization rate of resources.

[0006] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, in step (1), the binder is composed of the following raw materials by mass percentage: sodium carbonate 10-18%, calcium oxide 3-12%, borax 2-5%, sodium humate 10-25%, and the balance being sepiolite; the amount of the binder is 2-5% of the total mass of red mud and manganese ore powder. This invention uses a binder with specific components and proportions, utilizing the bonding properties of sodium carbonate, sodium humate, and sepiolite, combined with calcium oxide and borax, to strengthen the molding process, significantly improving the molding strength and thermal stability of the raw material pellets, and preventing the pellets from breaking and pulverizing during sintering and blast furnace smelting. Sepiolite, as an inorganic carrier, has extremely strong water absorption and plasticizing capabilities, not only absorbing excess moisture in the mixture to prevent pellet deformation, but also providing an attachment carrier for sodium humate, preventing excessive shrinkage and cracking of the organic film in the early stages of drying. It should be particularly noted that… Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, in step (2), the sintering temperature is 950~1100℃ and the sintering time is 45~60min. By controlling the appropriate sintering temperature and time, it is ensured that the coal powder inside the pellets partially combusts to provide heat and promotes solid-phase reactions between minerals to form binder phases such as silicates and calcium ferrites, thereby obtaining clinker pellets with sufficient mechanical strength and good metallurgical properties.

[0007] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, the manganese content in the manganese ore powder is not less than 40%. By limiting the manganese content of the manganese ore powder, it is ensured that the manganese grade in the manganese-rich slag after blast furnace smelting meets the requirements for subsequent manganese alloy production.

[0008] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, the particle size of the carbon-containing clinker pellets is 15~150mm.

[0009] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, in step (3), the flux is limestone, dolomite, quicklime, or fluorite, and the amount of flux used is 3-8% of the total mass of red mud and manganese ore powder. This invention effectively adjusts the alkalinity and melting temperature of blast furnace slag by adding a specific flux and controlling its dosage, thereby improving the slag's fluidity and promoting smooth separation of slag and iron.

[0010] Preferably, in the above-mentioned method for comprehensively treating red mud using the blast furnace method, the amount of anthracite used is 8-11% of the total mass of red mud and manganese ore powder. Controlling the appropriate proportion of anthracite provides an internal reducing atmosphere and some heat for pellet sintering, and at the same time, it acts as an auxiliary reducing agent in blast furnace smelting, reducing coke consumption.

[0011] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, the amount of coke used is 14-17% of the total mass of red mud and manganese ore powder.

[0012] Preferably, in the above-mentioned method for comprehensive treatment of red mud using the blast furnace method, in step (3), pig iron and manganese-rich slag are separated based on the density difference of the melt. The iron is reduced to molten metal and deposited at the bottom of the hearth, while the manganese enters the slag and becomes low-phosphorus, low-iron, manganese-rich slag that floats on the upper part of the hearth, thus obtaining pig iron and manganese-rich slag. By utilizing the density difference between molten iron and manganese-rich slag melt for natural stratification, with molten iron depositing at the bottom and manganese-rich slag floating on the top, precise physical separation of iron and manganese is achieved. The operation is simple and the separation purity is high. Compared with the prior art, the beneficial effects of the present invention are: 1. This invention prepares carbon-containing pellets by mixing red mud with manganese ore powder and then smelting them in a blast furnace. Utilizing the difference in reduction potential between iron and manganese at different temperatures, selective reduction is carried out at 1200~1350℃, allowing iron to be preferentially reduced into the metallic phase, while manganese remains in the slag phase as MnO. This achieves simultaneous and efficient recovery of iron resources from red mud and manganese resources from manganese ore, completely solving the problem of traditional processes that can only extract a single element, iron, and cause secondary pollution of tailings. The comprehensive utilization rate of resources is greatly improved.

[0013] 2. This invention uses a composite binder with a specific ratio, which significantly improves the pelletizing performance and pellet strength of the mixture of red mud and manganese ore powder, avoids pulverization during blast furnace smelting, and ensures the smooth operation of the smelting process.

[0014] 3. By rationally controlling sintering parameters, flux type and dosage, and the ratio of coke and anthracite, this invention optimizes the metallurgical properties and furnace thermal regime of blast furnace slag. Compared with the traditional blast furnace method for producing manganese-rich slag, it increases the yield of low-manganese pig iron, reduces coke consumption, and greatly enhances the profitability and market competitiveness of manganese-rich slag production. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a process flow diagram of the method for comprehensive treatment of red mud using the blast furnace method according to the present invention; Figure 2 The blast furnace with rich manganese slag used in this invention; Figure 3 This refers to the manganese-rich slag blast furnace top charging in this invention; Figure 4 The carbon-containing clinker pellets obtained by sintering in Example 1 of this invention; Figure 5 The image shows the low-manganese pig iron product prepared in Example 1 of this invention; Figure 6 This is a diagram of the manganese-rich slag product prepared in Example 1 of the present invention; Figure 7 This is a diagram of the multi-metal ingot prepared in Example 1 of the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be prepared by existing methods.

[0018] like Figure 1 As shown, this invention provides a method for the comprehensive treatment of red mud using a blast furnace process. This method achieves simultaneous and efficient recovery of iron resources from red mud and manganese resources from manganese ore through a process of mixing and pelletizing, sintering and granulation, and selective reduction smelting and separation. Specifically, it includes the following steps: (1) Red mud, manganese ore powder, binder and anthracite are mixed and stirred, wherein the mass ratio of red mud to manganese ore powder is 30~50:45~60, and then pressed into carbon-containing raw material pellets. Red mud, a solid waste slag rich in iron discharged during alumina production, has extremely fine iron mineral inclusions that are closely associated with silicates, making extraction from it alone extremely difficult. Manganese ore powder, on the other hand, provides the source of manganese in the system. This invention mixes the two at a specific mass ratio, allowing the iron in the red mud and the manganese in the manganese ore to complement and synergize in subsequent smelting. The ratio is limited to 30-50:50-70. When the proportion of red mud is too low and the proportion of manganese ore powder is too high, although the final grade of manganese slag may be high, the amount of red mud absorbed is extremely low, and there is a lack of sufficient iron oxides in the system to participate in the solid-phase reaction and build the framework. Conversely, when the proportion of red mud is too high and the proportion of manganese ore powder is too low, although iron reduction can still occur, the manganese grade in the manganese-rich slag will be severely insufficient, failing to meet the standards for a qualified raw material for manganese alloys. Furthermore, the excessive high-alkalinity substances inherent in the red mud will lead to an imbalance in the alkalinity of the slag and a sharp deterioration in its fluidity. Therefore, a ratio of 30-50:50-70 is the optimal balance between solid waste disposal volume and product qualification rate. In the pelletizing process, anthracite, as an internal carbon source, is evenly dispersed within the raw material pellets, providing a localized reducing atmosphere and heat for subsequent sintering and reduction.

[0019] (2) The carbon-containing raw material pellets obtained in step (1) are sintered, then crushed, screened and granulated to obtain sintered carbon-containing clinker pellets; the raw material pellets undergo a high-temperature solid-phase reaction in the sintering equipment, and silicates and calcium ferrites are generated between the minerals, so that the originally loose powder is solidified into clinker pellets with sufficient mechanical strength. The purpose of the crushing and screening process is to remove excessively large or small particle sizes to ensure that the particle size of the material fed into the furnace is uniform, and to provide a good permeability foundation for the blast furnace material layer; (3) The carbon clinker pellets, coke and flux obtained in step (2) are mixed and then put into the blast furnace for reduction smelting at 1200~1350℃. Then the slag and iron are separated to obtain manganese-rich slag and pig iron.

[0020] Using carbon-containing clinker in the furnace can reduce the low-temperature pulverization of manganese ore, improve the permeability of the furnace charge, improve the smelting conditions of the high-manganese slag blast furnace, and reduce coke consumption.

[0021] In blast furnaces, coke not only serves as the primary reducing agent, providing carbon, but also facilitates selective reduction reactions at temperatures controlled between 1200 and 1350°C. Within the blast furnace hearth, there is a significant difference in the chemical potentials for the reduction of iron and manganese: iron oxides have a low initial reduction temperature within this range and are readily reduced to molten iron by CO or C; while manganese oxides (especially MnO) have a much higher initial reduction temperature, requiring a higher thermodynamic driving force for their reduction. Therefore, by strictly controlling the furnace temperature between 1200 and 1350°C, the reduction reaction of manganese can be suppressed, allowing manganese to remain stably in the slag phase as MnO. This selective reduction based on the difference in thermodynamic chemical potential enables phase separation of iron and manganese within the same reactor: iron sinks to the metallic phase, while manganese floats to the slag phase. Finally, through slag-iron separation, the low-phosphorus, low-iron, and manganese-rich slag floating on top and the pig iron settling at the bottom are precisely extracted, completely avoiding the problems of traditional processes that can only extract a single element and require secondary waste of tailings, achieving simultaneous and efficient recovery of iron and manganese.

[0022] During blast furnace smelting, the large amounts of silicates and aluminates introduced by red mud and manganese ore powder make the formation temperature and viscosity characteristics of the initial slag extremely complex. Without intervention, the slag is prone to problems such as excessively high melting temperature or extremely poor fluidity, leading to difficulties in slag-iron separation and even causing severe conditions such as hearth accumulation. This embodiment introduces a specific type of flux to precisely adjust the basicity and physical properties of the slag, creating a suitable hydrodynamic environment for slag-iron separation.

[0023] The main components of the manganese-rich slag production process include: a charging system, a furnace top system, a blast furnace, a gas dust removal system, a hot blast stove, an iron (slag) tapping area, and a casting machine. The blast furnace is described below. Figure 2 The blast furnace top material distribution is shown below. Figure 3 .

[0024] Meanwhile, the waste gas (coal gas) is collected and purified, and then fully utilized as fuel for sintering machines, blast furnace hot blast stoves, and waste heat boilers. The high-temperature waste gas from the hot blast stoves, waste heat boilers, and blast furnace is collected and used as a heat source for drying red mud, achieving secondary reuse. The tail gas, after treatment to below emission standards, is then released in an organized manner. The flue gas (coal gas) dust from the blast furnace is rich in zinc and polymetallics; after collection by gravity dust collectors, bag filters, and electrostatic precipitators, it is treated as a byproduct.

[0025] The main components of the manganese ore and red mud used in the following examples and comparative examples are shown in Table 1. The main minerals in the South African manganese ore are manganese oxide, hematite, and silicon dioxide, while the main minerals in the Huasheng red mud are aluminum trihydrate, hematite, and silicon dioxide. The main associated minerals in both are hematite and silicon dioxide.

[0026] Table 1 Chemical composition of manganese ore and red mud (wt.%) Example 1 A method for comprehensive treatment of red mud using the blast furnace process includes the following steps: (1) Red mud, manganese ore powder, binder and anthracite are put into a mixing mixer and mixed. The mass ratio of red mud to manganese ore powder is 37.3:52.6. The binder is composed of the following raw materials by mass percentage: sodium carbonate 15%, calcium oxide 8%, borax 3.5%, sodium humate 17%, and the balance is sepiolite. The amount of binder is 3% of the total mass of red mud and manganese ore powder, and the amount of anthracite is 9.33% of the total mass of red mud and manganese ore powder. The mixture is fed into a double roller briquetting machine and pressed into carbon-containing raw material pellets. (2) The carbon-containing raw material pellets obtained in step (1) are sintered at 1000℃ for 50 min, then crushed, sieved and granulated to obtain blocks with a particle size of 15 mm to 150 mm, which are the sintered carbon-containing clinker pellets (see Figure 4 ); (3) The carbon-containing clinker pellets, coke, and flux obtained in step (2) are mixed together. The amount of coke is 15.38% of the total mass of red mud and manganese ore powder, and the amount of flux is 6.22% of the total mass of red mud and manganese ore powder. Then, the mixture is fed into the blast furnace. The hot blast stove heats the air to about 1150℃~1200℃ and blows it into the hearth of the blast furnace. By controlling the smelting temperature in the furnace to 1350℃, controlling the air volume and air temperature, the reduction of iron is used to inhibit the reduction of manganese, and iron, phosphorus and manganese are separated. Iron, phosphorus and a very small amount of other metals in the ore are reduced to liquid metal and deposited at the bottom of the hearth. Manganese enters the slag in the form of MnO and becomes low-phosphorus and low-iron rich manganese slag that floats in the upper part of the hearth. The blast furnace has one tapping port and one spare port. When tapping the slag, the molten iron with a higher specific gravity flows out from the tapping port first and flows into the casting machine to cast the ingots. After tapping the iron, the molten iron discharges liquid rich manganese slag from the tapping port and casts the ingots using slag molds. Pig iron is obtained separately (see Figure 5 ) and manganese-rich slag (see Figure 6 In addition, a small number of gold and silver polymetallic ingots were also obtained (see...). Figure 7 Byproducts such as )

[0027] The composition of the manganese-rich slag prepared in this embodiment is shown in Table 2, and the main components of the pig iron are shown in Table 3.

[0028] Table 2. Main components of manganese-rich slag products (wt.%) Table 3. Main components of pig iron (wt.%) As shown in Tables 2 and 3, the iron content in the manganese-rich slag prepared in this embodiment is less than 3%, the manganese content is greater than 30%, and the iron content in the pig iron is 92.25%. The iron recovery rate is 91.8%.

[0029] Example 2 Red mud, a solid waste rich in iron discharged during alumina production, has extremely fine-grained iron minerals that are closely associated with silicates, making extraction from it alone extremely difficult. Manganese ore powder, on the other hand, provides the source of manganese in the system. This invention mixes the two at a specific mass ratio, allowing the iron in the red mud and the manganese in the manganese ore to complement and synergize during subsequent smelting. To more clearly illustrate the beneficial effects of the red mud to manganese ore powder mass ratio in this invention, this embodiment compares and analyzes different red mud to manganese ore powder mass ratios. Other steps are the same as in Example 1, specifically including Comparative Group 2-1 and Comparative Group 2-2.

[0030] Comparative Group 2-1: The mass ratio of red mud to manganese ore powder was set at 20:80. In this system, the proportion of manganese ore powder was extremely high, while the proportion of red mud was low.

[0031] The results showed that although the large amount of manganese ore powder introduced resulted in a relatively high concentration of manganese in the manganese-rich slag floating on the top of the hearth after blast furnace smelting, and the manganese slag grade met the standards for high-quality raw materials, the problem was that red mud, as an industrial solid waste for comprehensive treatment and disposal, accounted for only 20% of the raw material system by mass. This meant that the amount of solid waste that could be treated in each batch of feed material was reduced, resulting in a low overall solid waste treatment capacity and fundamentally negating its core role and environmental significance as a comprehensive solid waste treatment method. Furthermore, due to the low amount of red mud introduced, the system lacked sufficient iron oxides and silicates to participate in slag formation and solid-phase skeleton reactions, compressing the adjustment of the physicochemical properties of the blast furnace slag and making it difficult to form a suitable alkalinity and fluidity window.

[0032] Comparative Group 2-2: The mass ratio of red mud to manganese ore powder was set at 60:40. Under this ratio, the proportion of red mud in the system was too high and the proportion of manganese ore powder was insufficient.

[0033] The results showed that the reduction of iron oxides in the red mud was still possible, and the output of pig iron settled at the bottom of the hearth increased. However, the quality of the manganese-rich slag decreased, with a Mn content of 30.12%. Due to the severely insufficient amount of manganese ore powder fed into the furnace, the total amount of MnO entering the slag phase after selective reduction was extremely low. Meanwhile, a large amount of gangue components such as silica and alumina accompanying the red mud entered the slag phase, resulting in a severely insufficient manganese grade in the final manganese-rich slag. This made it impossible to meet the downstream manganese alloy smelting industry's feeding standards for high-quality manganese-rich slag (usually requiring an Mn grade greater than 35%), rendering the process economically unprofitable in terms of resource recovery. Simultaneously, the excessive introduction of high-alkalinity substances from the red mud caused a severe imbalance in slag alkalinity, an abnormally high melting temperature, and a sharp deterioration in fluidity. This made the process prone to adverse conditions such as hearth accumulation and difficulty in slag-iron separation during blast furnace smelting, resulting in an iron content of 85.42% in the obtained pig iron.

[0034] In summary, neither excessively low nor excessively high red mud ratios can achieve simultaneous and efficient recovery of iron and manganese. This fully demonstrates that the mass ratio range of 30~50:50~70 defined in this invention is the optimal ratio for balancing solid waste disposal volume, product qualification rate, and smooth furnace operation.

[0035] Example 3 To further illustrate the beneficial effects of the adhesive of the present invention, this embodiment conducts a comparative analysis of the adhesive. The composition of the adhesive is different from that of Example 1, but the other steps are the same as those of Example 1. Specifically, it includes comparative group 3-1, comparative group 3-2 and comparative group 3-3.

[0036] Comparative Group 3-1: The binder is composed of the following raw materials by mass percentage: sodium carbonate 15%, calcium oxide 8%, sodium humate 17%, and the balance is sepiolite.

[0037] The results showed that the carbon-containing clinker pellets in the control group were extremely prone to violent pulverization in the blast furnace, with the originally strong clinker pellets instantly disintegrating into a large amount of fine powder. A possible reason for this is that when borax is lacking, the raw pellet sintering process lacks a liquid phase buffer and thermal stress release mechanism. The microscopic process of premature local liquid phase generation and filling of the solid-phase skeleton gaps, which is normally facilitated by borax, cannot occur. When the pellets encounter high-temperature thermal shock, the internal mineral phases generate enormous thermal stress due to differences in their expansion coefficients, and cannot be wetted and buffered by the liquid phase, leading to a sharp deterioration in the thermal stability of the pellets.

[0038] Comparative Group 3-2: The binder is composed of the following raw materials by mass percentage: sodium carbonate 15%, calcium oxide 8%, borax 3.5%, and the balance is sepiolite.

[0039] The results showed that, compared to Example 1, the raw material pellets in this control group were extremely prone to breakage during transport and distribution, with a 15% increase in breakage rate. Sodium humate played a role in the organic binder film formation during the room-temperature molding stage. When sodium humate was lacking, the raw material pellets lost the initial encapsulation and connection of the polymer binder film under cold pressing, directly resulting in extremely low initial molding strength. After demolding, the pellets could not maintain a complete spherical structure and were extremely prone to breakage during transport and distribution. A large amount of broken powder could not be successfully fed into the furnace for sintering, reducing the pelletizing rate and production efficiency of the sintering process.

[0040] Comparative Group 3-3: The binder is composed of the following raw materials by mass percentage: sodium carbonate 15%, calcium oxide 8%, borax 3.5%, sodium humate 17%, and the balance is montmorillonite.

[0041] The results showed that the compressive strength of the sintered clinker pellets was about 15.3% lower than that of pellets using sepiolite. The pulverization rate increased significantly after entering the blast furnace, leading to poor permeability of the feed bed, unsatisfactory furnace operation, and ultimately a decrease in iron recovery rate of about 8.3%. The Mn grade of the manganese-rich slag decreased by about 2.3% due to dilution by additional impurities. In contrast, the pellets using sepiolite exhibited excellent compressive strength after sintering, a low pulverization rate after entering the furnace, and smooth furnace operation.

[0042] Possible reasons for its existence: Montmorillonite is a layered mineral composed of hydrous aluminosilicates with a two-dimensional lamellar structure. At high temperatures, the interlayer bonding force decreases. In contrast, the fibrous crystal structure of sepiolite can maintain the basic structural integrity of the skeleton under high temperature conditions, providing continuous microscopic support for the solid-phase reaction during the sintering stage. This allows the silicate and calcium ferrite binder phase to remain on the fibrous skeleton, rather than collapsing and failing completely at high temperatures like montmorillonite, leaving voids and impurities.

[0043] Regarding the synergistic effect of the organic-inorganic interface, montmorillonite's interlayer adsorption sites are two-dimensional planar, and organic binders such as sodium humate can only adhere in a planar spreading manner between the layers, resulting in weak interfacial bonding. During the drying process, the organic film is easily peeled off from the montmorillonite interlayer, leading to the breakdown of the synergistic effect between the organic binder and the inorganic carrier. In contrast, the outer surface and internal pores of sepiolite's fibrous crystals provide sodium humate with far more abundant and robust three-dimensional adhesion sites than montmorillonite's interlayer adsorption, enabling a deeper interfacial bond between the organic film and the inorganic carrier, effectively preventing the organic film from peeling off from the carrier surface during drying. Furthermore, sepiolite has an extremely low Al2O3 content, avoiding the dilution of iron grade by impurities and ensuring the quality of the feed material from the source. The MgO content in sepiolite can improve slag fluidity and enhance blast furnace operation.

[0044] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for comprehensive treatment of red mud using the blast furnace method, characterized in that, Includes the following steps: (1) Red mud, manganese ore powder, binder and anthracite are mixed and stirred, wherein the mass ratio of red mud to manganese ore powder is 30~50:50~70, and then pressed into carbon-containing raw material pellets; (2) The carbon-containing raw material pellets obtained in step (1) are sintered, then crushed, screened and sized to obtain sintered carbon-containing clinker pellets; (3) The carbon clinker pellets, flux and coke obtained in step (2) are mixed and then put into the blast furnace for reduction smelting at 1200~1350℃. Then the slag and iron are separated to obtain manganese-rich slag and pig iron.

2. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, In step (1), the binder is composed of the following raw materials by mass percentage: sodium carbonate 10-18%, calcium oxide 3-12%, borax 2-5%, sodium humate 10-25%, and the balance being sepiolite; the amount of the binder is 2-5% of the total mass of red mud and manganese ore powder.

3. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, In step (2), the sintering temperature is 950~1100℃ and the sintering time is 45~60min.

4. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, The manganese content in the manganese ore powder is not less than 40%.

5. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, The particle size of the carbon-containing clinker pellets is 15~150mm.

6. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, In step (3), the flux is limestone, dolomite, quicklime or fluorite, and the amount of flux used is 3 to 8% of the total mass of red mud and manganese ore powder.

7. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, The amount of anthracite used is 8-11% of the total mass of red mud and manganese ore powder.

8. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, The amount of coke used is 14-17% of the total mass of red mud and manganese ore powder.

9. The method for comprehensive treatment of red mud using the blast furnace method according to claim 1, characterized in that, In step (3), pig iron and manganese-rich slag are separated based on the difference in melt density. Iron is reduced to molten metal and deposited at the bottom of the furnace hearth, while manganese enters the slag and becomes low-phosphorus, low-iron manganese-rich slag that floats on the upper part of the furnace hearth, thus obtaining pig iron and manganese-rich slag.

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