Flux pellet produced by adding steel slag and preparation method

Abstract

The invention relates to fluxed pellets produced by adding steel slag and a preparation method, and belongs to the technical field of metallurgy and chemical industry. The fluxed pellet is prepared from the following raw materials in parts by weight: 1 to 10 parts of steel slag, 90 to 99 parts of concentrate powder, 2 to 3.4 parts of alkalinity regulator and 1 to 1.6 parts of binder, the alkalinity of the fluxed pellet ore is 1.0 to 1.2. According to the method, the steel slag is added into the fluxed pellets to replace part of high-price pellet concentrate powder, slaked lime, light-burned dolomite and other fluxes, the alkalinity (R) of the pellets is controlled within the range of 1.0-1.2 by accurately controlling the proportion of all the components in the pellets, the production cost of the fluxed pellets is remarkably reduced, and the production efficiency of the fluxed pellets is improved. Meanwhile, Mg elements are introduced into the steel slag, so that the metallurgical performance of flux pellets is improved, the reduction expansion rate of the pellets is reduced, the compressive strength and the reduction degree of the pellets are improved, and the flux pellets are more suitable for being used in blast furnaces.

Description

Technical Field

[0001] The present application relates to the technical field of metallurgy and chemical industry, and in particular to a flux-type pellet ore produced by adding steel slag and a preparation method thereof. Background Art

[0002] In the steel production process, pellets are an important raw material and are widely used in blast furnace smelting. Traditionally, pellets are mainly divided into two categories: ordinary acid pellets and flux pellets. The main difference between them lies in the binary basicity (R=CaO / SiO2) in the composition. Ordinary pellets have a low CaO content in their natural composition due to their simple ingredients and lax control of composition. The binary basicity (R) is usually less than 0.3. In contrast, flux pellets are gradually increasing in proportion in blast furnaces because they can significantly reduce the coke ratio and fuel ratio in the blast furnace smelting process, thereby reducing carbon emissions and energy consumption. In order to produce flux pellets that meet the requirements (R≥0.8), a certain amount of slaked lime (Ca(OH)2) or limestone powder (CaCO3) needs to be added during the production process to increase the CaO content. In addition, studies have found that adding MgO-containing substances to flux pellets can significantly improve the physical and metallurgical properties of the pellets. However, in the existing technology, CaO-containing fluxes, such as slaked lime and limestone powder, and MgO-containing fluxes, such as light-burned dolomite and serpentine, are often expensive, which increases the cost of ore blending and reduces the market competitiveness of pellets.

[0003] On the other hand, steel slag, a large byproduct produced during the steelmaking process, has long had a low utilization rate. The primary chemical components of steel slag are CaO, followed by SiO2 and FeO. It also contains small amounts of MgO and P2O5, which are similar to the raw materials used in the production of flux pellets.

[0004] Therefore, there is an urgent need to develop a new technology that can reduce production costs, increase slag utilization, and improve the performance of flux pellets. Summary of the Invention

[0005] The present application provides a flux pellet produced by adding steel slag and a preparation method thereof, in order to solve the following technical problem: how to reasonably utilize the valuable elements in steel slag.

[0006] In a first aspect, an embodiment of the present application provides a flux pellet produced by adding steel slag, wherein the raw materials of the flux pellet include, by weight: 1 to 10 parts of steel slag, 90 to 99 parts of concentrate powder, 2 to 3.4 parts of alkalinity regulator, and 1 to 1.6 parts of binder;

[0007] The basicity of the flux pellets is 1.0 to 1.2.

[0008] Optionally, the raw materials of the flux pellets include, in parts by weight: 2 to 6 parts of steel slag, 92 to 96 parts of concentrate powder, 2.8 parts of alkalinity regulator and 1 part of binder.

[0009] Optionally, the mass of the steel slag with a particle size of -200 mesh is greater than 80% of the total mass of the steel slag.

[0010] Optionally, the water content of the steel slag is less than 10% by mass.

[0011] Optionally, the binder is at least one of calcium-based bentonite, sodium-based bentonite and composite bentonite.

[0012] Optionally, the concentrate powder is at least one of magnetite and hematite.

[0013] Optionally, the alkalinity regulator is at least one of slaked lime and limestone; wherein,

[0014] The mass of the slaked lime having a particle size of less than 200 mesh is greater than 95% of the total mass of the slaked lime;

[0015] The mass of the limestone with a particle size less than 325 mesh is greater than 90% of the total mass of the limestone.

[0016] In a second aspect, an embodiment of the present application provides a method for preparing the flux pellets described in the first aspect, the method comprising:

[0017] Mixing the steel slag, the concentrate powder, the alkalinity regulator, and the binder according to the weight parts to obtain a premix;

[0018] The premix is ​​pelletized and sieved in sequence to obtain green pellets;

[0019] The green pellets are sequentially dried, preheated, roasted and cooled to obtain finished flux pellets.

[0020] Optionally, the premix is ​​pelletized and sieved in sequence to obtain green pellets, comprising:

[0021] Water is added to the premix to form balls, wherein the water content is 8% to 9% by mass; and green balls with a particle size of 8mm to 16mm are obtained by screening.

[0022] Optionally, the preheating temperature is 650° C. to 1120° C., and the preheating time is 6 min to 7.5 min.

[0023] Optionally, the calcination temperature is 1220° C. to 1280° C., and the calcination time is 8.3 min to 10.6 min.

[0024] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0025] The present invention provides a flux pellet produced by adding steel slag. The raw materials of the flux pellet include, by weight, 1 to 10 parts of steel slag, 90 to 99 parts of fine ore concentrate, 2 to 3.4 parts of alkalinity regulator, and 1 to 1.6 parts of binder. The alkalinity of the flux pellet is 1.0 to 1.2. By adding steel slag to the flux pellet to replace part of the expensive flux such as pellet concentrate powder, slaked lime, and light-burned dolomite, and by precisely controlling the ratio of each component in the pellet, the alkalinity (R) of the pellet is controlled within the range of 1.0 to 1.2. This not only significantly reduces the production cost of the flux pellet, but also improves the metallurgical properties of the flux pellet by introducing Mg into the steel slag, reduces the reduction expansion rate of the pellet, and increases its compressive strength and reduction degree, making it more suitable for use in blast furnaces. This provides a new way to utilize steel slag, increases its recycling value, and reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A schematic flow chart of a method for preparing flux pellets produced by adding steel slag provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation to the scope of the present application; therefore, it should be considered that the range description has disclosed all possible sub-ranges and single values within the range; for example, it should be considered that the range description from 1 to 6 has disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single values such as 1, 2, 3, 4, 5, and 6, which are applicable regardless of the range; in addition, whenever a numerical range is indicated herein, it refers to any cited number (fraction or integer) within the indicated range.

[0031] In the present text, the term including "comprising" and the like means "including but not limited to". The relational terms such as "first" and "second" and the like are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between the entities or operations. "And / or", which describes the association between the associated objects, means that there can be three relationships, for example, A and / or B can mean: A alone, A and B together, B alone; where A and B can be singular or plural. "At least one" means one or more, "multiple" means two or more; "at least one", "at least one of the following" or the like means any combination of the items, including single item or any combination of multiple items; for example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. "Fractional representation" such as weight parts, mass parts, etc. represents the proportional relationship between components. In the proportional relationship described herein, the parameters that need to be described by proportion should be understood as the first term of the proportion formula in the order of description, and the proportional number should be understood as the latter term of the proportion formula, for example, the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should be one-to-one corresponding in the proportion formula according to the description order, i.e. the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0032] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment, etc. used in the present text can be purchased from the market or can be prepared by existing methods.

[0033] In a first aspect, an embodiment of the present application provides a flux pellet produced by adding steel slag, wherein the raw materials of the flux pellet include, by weight: 1 to 10 parts of steel slag, 90 to 99 parts of concentrate powder, 2 to 3.4 parts of alkalinity regulator, and 1 to 1.6 parts of binder;

[0034] The basicity of the flux pellets is 1.0 to 1.2.

[0035] Using steel slag as a raw material for pellets can partially replace expensive resources such as pellet concentrate powder, slaked lime, and light-burned dolomite, thereby achieving efficient resource reuse and reducing the reduction expansion rate of pellets. In the embodiment of the present application, alkaline steel slag is used, and the sum of the mass fractions of CaO and MgO in the steel slag is greater than 40%. The reason for controlling the weight of steel slag to 1 to 10 parts is to ensure good compressive strength of the pellets and a low reduction expansion rate. If the weight of steel slag is greater than 10 parts, it may affect the pelletizing process, reduce the compressive strength of the green balls, and increase the wet return rate. If the weight of steel slag is less than 1 part, the reduction expansion rate of the pellets may not be reduced.

[0036] Concentrate fines are the main carrier of iron in pellets. During pellet preparation, concentrate fines ensure high iron content in the pellets, which is crucial for iron reduction and extraction during blast furnace smelting.

[0037] The function of the alkalinity regulator is to control the production of pellets with appropriate alkalinity, and ultimately achieve that the alkalinity of the entire pellet is controlled within the range of 1.0 to 1.2.

[0038] The role of the binder is to improve the pelletizing performance of the pellets, improve the chemical composition of the pellets, so as to increase the strength of the pellets and improve the metallurgical properties. The principle of controlling the amount of binder is to minimize the introduction of harmful elements (Na, K) as much as possible under the premise of ensuring the strength of the pellets. The adverse effect of the binder weight being greater than 1.6 parts is that the gangue content SiO2 in the pellets increases and the content of harmful elements (Na, K) increases. The adverse effect of the binder weight being less than 1.0 parts is that the pelletizing is difficult, the compressive strength of the green balls is low, and the quality of the pellets is poor.

[0039] In some embodiments, the raw materials of the flux pellets include, by weight, 2 to 6 parts of steel slag, 92 to 96 parts of concentrate powder, 2.8 parts of alkalinity regulator, and 1 part of binder.

[0040] In some embodiments, the mass of the steel slag with a particle size of -200 mesh is greater than 80% of the total mass of the steel slag.

[0041] The reason for controlling the mass of steel slag with a particle size of -200 mesh to be greater than 80% of the total mass of steel slag is to increase the specific surface area of ​​finely ground steel slag and enhance the ball-forming performance. The adverse effect of this proportion being less than or equal to 80% is detrimental to the ball-forming process, reducing the strength of the green balls, and causing poor ball-forming properties, which affects production and quality.

[0042] In some embodiments, the water content of the steel slag is less than 10% by mass.

[0043] The reason for controlling the water content of steel slag to be less than 10% is that this water content is the optimal moisture range for pelletizing. If the water content of steel slag is greater than or equal to 10%, it may cause the green balls to be too large or the green balls to stick together, affecting the green ball formation rate, and may cause cracks during preheating and roasting, or even burst into broken balls.

[0044] In some embodiments, the binder is at least one of calcium bentonite, sodium bentonite, and composite bentonite.

[0045] Calcium bentonite is a natural layered silicate mineral with excellent water absorption, swelling, and bonding properties. During pellet production, calcium bentonite effectively binds raw materials such as concentrate, steel slag, and alkalinity regulator together, forming densely structured pellets. Its excellent water absorption helps regulate the moisture content of the green pellets, ensuring pellet stability during drying, preheating, and roasting.

[0046] Similar to calcium bentonite, sodium bentonite also exhibits good bonding and water absorption. However, sodium bentonite is more dispersible in water, forming a finer slurry that facilitates green ball formation and stability. Furthermore, sodium bentonite exhibits high heat resistance and chemical stability, maintaining the structural integrity of the pellets during the roasting process.

[0047] Composite bentonite is made by mixing calcium-based bentonite, sodium-based bentonite, or other types of bentonite in a specific ratio according to specific needs. By adjusting the ratio of different bentonite types, the performance of the binder can be further optimized to meet the special needs of the pellet production process.

[0048] In some embodiments, the concentrate powder is at least one of magnetite and hematite.

[0049] Magnetite (primarily composed of Fe₃O₄) is a magnetic iron ore with excellent magnetic properties, making it easily enriched by magnetic separation. It typically contains a high iron grade and is one of the most common and important types of iron ore. During pellet production, magnetite's magnetic properties make it easy to handle and recover, helping to improve the iron content and overall quality of the pellets.

[0050] Hematite (mainly Fe2O3) is a reddish-brown iron ore that exists in the form of iron oxide. Compared with magnetite, hematite has weaker or no magnetic properties, but its iron content is also high and its resources are abundant in certain areas.

[0051] In the examples of this application, magnetite and hematite are selected as the concentrate powder, taking into account the wide range and availability of resources while fully utilizing the advantages of these two iron ores. By selecting magnetite and hematite as the concentrate powder, the chemical composition and physical properties of the pellets can be optimized to meet the different requirements of blast furnace smelting for pellets.

[0052] In some embodiments, the alkalinity regulator is at least one of slaked lime and limestone; wherein,

[0053] The mass of the slaked lime having a particle size of less than 200 mesh is greater than 95% of the total mass of the slaked lime;

[0054] The mass of the limestone with a particle size less than 325 mesh is greater than 90% of the total mass of the limestone.

[0055] Slaked lime (Ca(OH)2) and limestone (CaCO3) are the primary raw materials for regulating the alkalinity of pellets. In the examples of this application, the slaked lime and limestone used in the alkalinity regulator are required to meet specific particle size requirements. This requirement ensures that the slaked lime and limestone particles are small and uniform, facilitating their rapid dissolution and reaction during pellet preparation, thereby more effectively regulating the alkalinity of the pellets.

[0056] Figure 1 A schematic flow chart of a method for preparing flux pellets produced by adding steel slag provided in an embodiment of the present application.

[0057] See Figure 1 In a second aspect, an embodiment of the present application provides a method for preparing the flux pellets described in the first aspect, the method comprising:

[0058] S1. Mixing the steel slag, the concentrate powder, the alkalinity regulator, and the binder according to the weight parts to obtain a premix;

[0059] S2, pelletizing and screening the premix in sequence to obtain green pellets;

[0060] In some embodiments, the pelletizing and screening the premix in sequence to obtain green pellets comprises:

[0061] Water is added to the premix to form balls, wherein the water content is 8% to 9% by mass; and green balls with a particle size of 8mm to 16mm are obtained by screening.

[0062] In order to meet the particle size of the raw balls, the raw balls need to be screened, and the qualified ones will be sent to the next step, and the unqualified ones will be returned and re-balled.

[0063] S3. Drying, preheating, roasting and cooling the green balls in sequence to obtain finished flux pellets.

[0064] In some embodiments, the preheating temperature is 650° C. to 1120° C., and the preheating time is 6 min to 7.5 min.

[0065] The selection of preheating temperature requires balancing multiple factors. Preheating temperatures below 650°C may result in incomplete chemical reactions within the pellets, such as the decomposition of water of crystallization and the calcination of sulfides, which in turn may affect the pellets' compressive strength. Furthermore, preheating temperatures below 650°C may also cause cracks in the pellets during roasting due to uneven internal stress, affecting their overall quality. Conversely, preheating temperatures exceeding 1120°C, while accelerating chemical reactions, may also cause a hard shell to form too quickly on the pellets' outer layer, hindering the diffusion of oxygen within the pellets and thus affecting the oxidation reaction within the pellets, similarly leading to a reduction in compressive strength.

[0066] If the preheating time is less than 6 minutes, the chemical reaction within the pellets may not be complete. This is especially true for large pellets, where unreacted components may remain, resulting in insufficient compressive strength. Furthermore, a preheating time of less than 6 minutes may cause thermal stress during the roasting process due to the large temperature difference between the inside and outside of the pellets, leading to cracks or even explosions. Conversely, if the preheating time exceeds 7.5 minutes, while sufficient chemical reactions within the pellets can be ensured, it will increase production costs and reduce production efficiency. Furthermore, a preheating time exceeding 7.5 minutes may cause the outer layer of the pellets to oversinter, forming a hard shell that impedes further diffusion of oxygen within the pellets.

[0067] In some embodiments, the calcination temperature is 1220° C. to 1280° C., and the calcination time is 8.3 min to 10.6 min.

[0068] If the roasting temperature is lower than 1220°C, the iron oxides may not be fully oxidized and strong Fe2O3 recrystallized bonds may not be formed, which will reduce the strength of the pellets and affect their performance in practical applications. Furthermore, roasting temperatures below 1220°C may also leave unreacted components inside the pellets, affecting their overall performance. Conversely, if the roasting temperature exceeds 1280°C, while sufficient oxidation of the iron oxides is ensured, an excessive amount of liquid phase may be produced. This liquid phase may hinder further oxidation of the iron oxides and even lead to their decomposition, thereby reducing the reduction degree of the pellets. Furthermore, roasting temperatures exceeding 1280°C may increase energy consumption and production costs.

[0069] Roasting times shorter than 8.3 minutes may not ensure full oxidation and recrystallization of the iron oxides, resulting in insufficient pellet strength. Unreacted components or gases may also remain within the pellets, impacting their performance and stability. However, roasting times exceeding 10.6 minutes, while ensuring full oxidation and recrystallization of the iron oxides, increase production costs and energy consumption. Furthermore, it may overburn the pellets, causing cracks or deformation, reducing their quality.

[0070] The adoption of the technical solution of the present application can significantly improve the recycling value of steel slag and realize the efficient resource utilization of valuable elements such as Fe, Ca, Mg, and Si in steel slag. By adding finely ground steel slag to the production of flux pellets, not only the production cost is reduced, but also pellets with excellent quality, environmental friendliness, and relatively low cost are successfully prepared. In addition, the addition of steel slag also effectively reduces the reduction expansion rate of the pellets and improves their performance in the blast furnace smelting process. In summary, the technical solution of the present application not only has significant economic benefits, but also brings obvious environmental benefits by reducing waste emissions and improving resource utilization efficiency.

[0071] The product prepared by the method for preparing flux pellets is the flux pellets produced by adding steel slag as described above. Since the method for preparing flux pellets adopts part or all of the technical solutions of the embodiment of flux pellets produced by adding steel slag, it has at least all the beneficial effects brought by the technical solutions of the embodiment of flux pellets produced by adding steel slag, which will not be described one by one here.

[0072] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0073] Example 1

[0074] Fine grinding of steel slag: The steel slag is finely ground to a particle size of -200 mesh, accounting for 83%, and the water content of the steel slag is 9.5%.

[0075] Ingredients: By weight, mix 1 part of steel slag, 97 parts of magnetite, 2 parts of hematite, 2.05 parts of slaked lime, 0.8 parts of limestone, and 1.1 parts of calcium-based bentonite.

[0076] Ball making: On a disc ball making machine, add water to make balls, the water content is 8.5%; use a double-layer roller screen to screen out qualified green balls with a particle size of 8mm-16mm.

[0077] Calcination: Place qualified green pellets of 8mm-16mm into a belt roaster for drying, preheating, and roasting. The preheating temperature is 680℃-1120℃ for 6.5 minutes; the roasting temperature is 1230℃ for 10 minutes.

[0078] Cooling: Cool to below 120℃ in the cooling section of the belt roaster.

[0079] Example 2

[0080] Finely grind the steel slag, and adopt a ball mill wet grinding process to finely grind the steel slag to a particle size of -200 mesh, accounting for 85%, and the water content of the steel slag is 9.8%.

[0081] Ingredients: By weight, mix 3 parts of steel slag, 97 parts of magnetite, 1.75 parts of slaked lime, 0.8 parts of limestone, and 1.12 parts of calcium-based bentonite.

[0082] Ball making: On a disc ball making machine, add water to make balls, the water content is 8.5%; use a double-layer roller screen to screen out qualified green balls with a particle size of 8mm-16mm.

[0083] Calcination: Place qualified green pellets of 8mm-16mm into a belt roaster for drying, preheating, and roasting. The preheating temperature is 690℃-1120℃ for 7 minutes; the roasting temperature is 1240℃ for 10.5 minutes.

[0084] Cooling: Cool to below 120℃ in the cooling section of the belt roaster.

[0085] Example 3

[0086] Fine grinding of steel slag: First, a ball mill wet grinding process is used to finely grind the steel slag to a particle size of -200 mesh, accounting for 83%, and the water content of the steel slag is 9.7%.

[0087] Ingredients: By weight, mix 6 parts of steel slag, 94 parts of magnetite, 1.4 parts of slaked lime, 0.8 parts of limestone, and 1.15 parts of calcium-based bentonite.

[0088] Ball making: On a disc ball making machine, add water to make balls, the water content is 8.5%; use a double-layer roller screen to screen out qualified green balls with a particle size of 8mm-16mm.

[0089] Calcination: Place qualified green pellets of 8mm-16mm into a belt roaster for drying, preheating, and roasting. The preheating temperature is 680℃~1120℃ for 6 minutes; the roasting temperature is 1250℃ for 10 minutes.

[0090] Cooling: Cool to below 120℃ in the cooling section of the belt roaster.

[0091] Comparative Example 1

[0092] Fine grinding of steel slag: First, a ball mill wet grinding process is used to finely grind the steel slag to a particle size of -200 mesh, accounting for 83%, and the water content of the steel slag is 9.5%.

[0093] Ingredients: By weight, mix 0 parts of steel slag, 97 parts of magnetite, 6 parts of hematite, 2.4 parts of slaked lime, 0.8 parts of limestone, and 1.1 parts of calcium-based bentonite.

[0094] Ball making: On a disc ball making machine, add water to make balls, the water content is 8.5%; use a double-layer roller screen to screen out qualified green balls with a particle size of 8mm-16mm.

[0095] Calcination: Place qualified green pellets of 8mm-16mm into a belt roaster for drying, preheating, and roasting. The preheating temperature is 680℃-1120℃ for 4.5 minutes; the roasting temperature is 1220℃ for 10 minutes.

[0096] Cooling: Cool to below 120℃ in the cooling section of the belt roaster.

[0097] Comparative Example 2

[0098] Fine grinding of steel slag: First, a ball mill wet grinding process is used to finely grind the steel slag to a particle size of -200 mesh, accounting for 83%, and the water content of the steel slag is 9.5%.

[0099] Ingredients: By weight, mix 12 parts of steel slag, 88 parts of magnetite, 4 parts of hematite, 1.0 part of slaked lime, 0.8 part of limestone, and 1.25 parts of calcium-based bentonite.

[0100] Ball making: On a disc ball making machine, add water to make balls, the water content is 8.5%; use a double-layer roller screen to screen out qualified green balls with a particle size of 8mm-16mm.

[0101] Calcination: Place qualified green pellets of 8mm-16mm into a belt roaster for drying, preheating, and roasting. The preheating temperature is 680℃-1120℃ for 6.5 minutes; the roasting temperature is 1220℃ for 10 minutes.

[0102] Cooling: Cool to below 120℃ in the cooling section of the belt roaster.

[0103] The pellets prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0104] Table 1

[0105]

[0106] It can be seen from the data in the above table that the pellets prepared using the ratio and method provided in the examples of the present application have an effectively reduced reduction expansion rate, maintained below 13%; and improved compressive strength and reduction degree.

[0107] One or more technical solutions in the embodiments of the present invention may have at least the following technical effects or advantages:

[0108] (1) The method for preparing pellets provided in the embodiments of the present application provides a new way to use steel slag, which solves the technical problems existing in the existing steel slag use technology, such as increased sintering fuel consumption, decreased quality, and low environmental, social and economic benefits of products, and increases the reuse value of steel slag.

[0109] (2) The method for preparing pellets provided in the embodiments of the present application efficiently utilizes steel slag to replace part of the concentrate powder used in pellets, thereby reducing costs and increasing efficiency, producing pellets with excellent quality, environmental friendliness, and high cost-effectiveness, improving the use value of steel slag, and creating greater environmental, social, and economic benefits.

[0110] (3) The method for preparing pellets provided in the embodiments of the present application can efficiently utilize the valuable elements such as Fe, Ca, Mg, and Si in steel slag as resources, and can produce pellets with excellent quality, environmental friendliness, and low cost.

[0111] (4) The pellets provided in the embodiments of the present application have high compressive strength, and the reduction expansion rate of the pellets is maintained at a low level.

[0112] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A flux pellet produced by adding steel slag, wherein the raw materials of the flux pellet include, in parts by weight: 1 to 10 parts of steel slag, 90 to 99 parts of concentrate powder, 2 to 3.4 parts of alkalinity regulator and 1 to 1.6 parts of binder; The basicity of the flux pellets is 1.0 to 1.

2.

2. The flux pellet according to claim 1, characterized in that: In parts by weight, the raw materials of the flux pellets include: 2 to 6 parts of steel slag, 92 to 96 parts of concentrate powder, 2.8 parts of alkalinity regulator and 1 part of binder.

3. The flux pellet according to claim 1 or 2, characterized in that: The mass of the steel slag with a particle size of -200 mesh is greater than 80% of the total mass of the steel slag.

4. The flux pellet according to claim 1 or 2, characterized in that: Calculated by mass fraction, the water content of the steel slag is less than 10%.

5. The flux pellet according to claim 1 or 2, characterized in that: The binder is at least one of calcium bentonite, sodium bentonite and composite bentonite; and / or, The concentrate powder is at least one of magnetite and hematite.

6. The flux pellet according to claim 1 or 2, characterized in that: The alkalinity regulator is at least one of slaked lime and limestone; wherein, The mass of the slaked lime having a particle size of less than 200 mesh is greater than 95% of the total mass of the slaked lime; The mass of the limestone with a particle size less than 325 mesh is greater than 90% of the total mass of the limestone.

7. A method for preparing flux pellets according to any one of claims 1 to 6, comprising: Mixing the steel slag, the concentrate powder, the alkalinity regulator, and the binder according to the weight parts to obtain a premix; The premix is ​​pelletized and sieved in sequence to obtain green pellets; The green pellets are sequentially dried, preheated, roasted and cooled to obtain finished flux pellets.

8. The method according to claim 7, characterized in that The process of sequentially pelletizing and screening the premix to obtain green pellets comprises: Water is added to the premix to form balls, wherein the water content is 8% to 9% by mass; and green balls with a particle size of 8mm to 16mm are obtained by screening.

9. The method according to claim 7, characterized in that The preheating temperature is 650° C. to 1120° C., and the preheating time is 6 min to 7.5 min.

10. The method according to claim 7, characterized in that The calcination temperature is 1220° C. to 1280° C., and the calcination time is 8.3 min to 10.6 min.

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