Low alkali metal pellets

Abstract

The application relates to the technical field of blast furnace smelting, in particular to a low-alkali metal pellet. The raw materials of the low-alkali metal pellet include fine powder, ore powder and bentonite; wherein the content of the fine powder is 85-95% by weight, the content of the ore powder is 5-15% by weight, and the weight of the bentonite is set according to the category of the bentonite. The application can reduce the alkali metal content in the pellet, thereby reducing the alkali metal content in the furnace raw material, achieving cost reduction and benefit increase, and the method is simple and easy to operate, and has a wide application prospect.

Description

Technical Field

[0001] This application relates to the field of blast furnace smelting technology, and in particular to a low-alkali metal pellet. Background Technology

[0002] Alkali metals pose a significant threat to blast furnace production. Alkali metals such as potassium (K) and sodium (Na) can cause hearth buildup, blast furnace lining defects, deterioration of permeability, damage to furnace walls, and severe malfunctions. In the past, the destructive potential of alkali metals like K and Na was insufficiently recognized. In recent years, several accidents involving hearth rise, tuyeres warping, lining flattening, and even hearth burn-through have brought this issue to the forefront of public attention. Alkali metals like K and Na also degrade coke, causing coke pulverization within the furnace and affecting blast furnace permeability and smooth operation. Simultaneously, a small amount of alkali metals introduced into the furnace burden is carried away by the gas and slag, while the majority circulates and accumulates within the furnace. In severe cases, the amount of alkali metals in the furnace can exceed ten times the amount of alkali metals introduced into the furnace, thus harming blast furnace production, corroding the blast furnace lining and shortening its lifespan, and causing significant damage to blast furnace operation. This is mainly manifested in the following aspects:

[0003] (1) Alkali metals accelerate the deterioration process of coke and affect the permeability of blast furnace charge and the working condition of hearth.

[0004] (2) Alkali metals disrupt the smooth operation of the blast furnace. Alkali metals in the iron-containing materials fed into the furnace are prone to form low-melting-point compounds, which leads to the upward movement of the softening zone and the increase of resistance to the rise of gas. At the same time, alkali metals can, to a certain extent, deteriorate the medium-temperature reduction and pulverization performance of sinter and affect the permeability of the material layer.

[0005] (3) Excessive alkali metal load accelerates the erosion rate of the furnace lining, which is detrimental to the long service life of the blast furnace. Summary of the Invention

[0006] This application provides a low-alkali metal pellet to solve the technical problem of excessively high alkali metal content in existing pellets.

[0007] In a first aspect, this application provides a low-alkali metal pellet, the raw materials of which include:

[0008] Concentrated flour, mineral powder, and bentonite; among which,

[0009] The content of the refined powder is 85% to 95% by weight, the content of the mineral powder is 5% to 15% by weight, and the weight of the bentonite is set according to the type of bentonite.

[0010] Optionally, setting the weight of the bentonite according to its type includes:

[0011] If the bentonite is sodium-based bentonite, then the content of sodium-based bentonite is 0.8% to 1.5% by weight.

[0012] Optionally, the sodium-based bentonite content is 0.8% to 1.0% by weight.

[0013] Optionally, the alkali metal component of the sodium-based bentonite includes: K₂O and Na₂O; wherein,

[0014] The K2O content is 0.1% to 0.5% by weight, and the Na2O content is 2.0% to 4.0% by weight.

[0015] Optionally, setting the weight of the bentonite according to its type includes:

[0016] If the bentonite is calcium-based bentonite, then the content of calcium-based bentonite is 1.7% to 2.5% by weight.

[0017] Optionally, the content of the calcium-based bentonite is 1.7% to 2.0% by weight.

[0018] Optionally, the alkali metal components of the calcium-based bentonite include: K₂O and Na₂O; wherein,

[0019] The K2O content is 0.1% to 0.5% by weight, and the Na2O content is 0.1% to 0.5% by weight.

[0020] Optionally, the alkali metal component of the refined powder includes: K₂O and Na₂O; wherein,

[0021] The K2O content is 0.01% to 0.2% by weight, and the Na2O content is 0.1% to 0.4% by weight.

[0022] Optionally, the alkali metal component of the mineral powder includes: K₂O and Na₂O; wherein,

[0023] The K2O content is 0.01% to 0.1% by weight, and the Na2O content is 0.01% to 0.1% by weight.

[0024] The technical solutions provided in this application have the following advantages compared with the prior art:

[0025] The low-alkali metal pellets provided in this application reduce the alkali metal content in the pellets by adding low-alkali metal bentonite and reducing the proportion of bentonite used in the pellets, ultimately solving the problem of high alkali metal content in pellets. Using concentrate and ore powder as the main raw materials, sodium-based bentonite and calcium-based bentonite are added as supplementary ingredients. Although sodium-based bentonite itself contains a high alkali metal content, this can be reduced by lowering the addition ratio. Calcium-based bentonite itself contains a low alkali metal content, so even a higher addition ratio can still achieve the goal of reducing the alkali metal content in the pellets. Whether adding two types of sodium-based bentonite in low proportions or adding calcium-based bentonite, which itself has a low alkali metal content, the goal of reducing alkali metal content in the pellets can be achieved, thereby reducing the alkali metal content in the raw materials fed into the furnace, achieving cost reduction and efficiency improvement. The method is simple and easy to operate, and has broad application prospects. Attached Figure Description

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

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1-2 A microstructure diagram of a low-alkali metal pellet provided in an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0031] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0032] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0033] Firstly, this application provides a low-alkali metal pellet, please refer to [link to relevant documentation]. Figure 1-2 The raw materials for the low-alkali metal pellets include:

[0034] Concentrated flour, mineral powder, and bentonite; among which,

[0035] The content of the refined powder is 85% to 95% by weight, the content of the mineral powder is 5% to 15% by weight, and the weight of the bentonite is set according to the type of bentonite.

[0036] To ensure normal blast furnace smelting and achieve good technical indicators, an effective method is to control the alkali metal content in the feed and increase the amount of alkali metal discharged. Through investigation, the alkali load of a certain blast furnace has been consistently around 3.0 kg / t, of which 1.39 kg / t (45%) is carried in by pellets. Therefore, reducing the alkali metal content of the pellets is an important way to reduce the blast furnace alkali load. Reducing the alkali metal content of the pellets is mainly achieved by reducing the alkali metal content in the pellet feed and increasing the proportion of low-alkali metal feedstocks.

[0037] The low-alkali metal pellets provided in this application reduce the alkali metal content in the pellets by adding low-alkali metal bentonite and reducing the proportion of bentonite used in the pellets, ultimately solving the problem of high alkali metal content in pellets. Using concentrate and ore powder as the main raw materials, sodium-based bentonite and calcium-based bentonite are added as supplementary ingredients. Although sodium-based bentonite itself contains a high alkali metal content, this can be reduced by lowering the addition ratio. Calcium-based bentonite itself contains a low alkali metal content, so even a higher addition ratio can still achieve the goal of reducing the alkali metal content in the pellets. Whether adding two types of sodium-based bentonite in low proportions or adding calcium-based bentonite, which itself has a low alkali metal content, the goal of reducing alkali metal content in the pellets can be achieved, thereby reducing the alkali metal content in the raw materials fed into the furnace, achieving cost reduction and efficiency improvement. The method is simple and easy to operate, and has broad application prospects.

[0038] Mineral concentrate is the main raw material for pelletizing. It is mineral powder produced from ore through crushing, grinding, and beneficiation. Controlling the content of mineral concentrate to 85% to 95% by weight has the positive effect of serving as the main raw material. If the content of mineral concentrate is too low, it may lead to poor pelletizing results to some extent. Specifically, the content of mineral concentrate can be 85% by weight, 90% by weight, 95% by weight, etc. In the embodiments of this application, domestic mineral concentrate with a mesh size of less than 200 is used.

[0039] Mineral powder generally refers to the powder obtained after crushing mined ore. Controlling the mineral powder content to 5% to 15% by weight has the following positive effects: it serves as an auxiliary raw material, reduces the alkali metal content of the finished pellets, and ensures the reduction expansion rate of the finished pellets. If the mineral powder content is too high, it will increase the alkali metal content of the finished pellets to some extent; if the mineral powder content is too low, it may lead to poor subsequent pelletizing results to some extent. Specifically, the mineral powder content can be 5% by weight, 10% by weight, 15% by weight, etc. In the embodiments of this application, African mineral powder is used.

[0040] In some embodiments, setting the weight of the bentonite according to its type includes:

[0041] If the bentonite is sodium-based bentonite, then the content of sodium-based bentonite is 0.8% to 1.5% by weight.

[0042] Bentonite is a non-metallic mineral with montmorillonite as its main mineral component. It has a binding effect, and controlling the content of sodium-based bentonite to be between 0.8% and 1.5% by weight has the following positive effects: Although sodium-based bentonite itself contains a relatively high alkali metal content, the alkali metal content of the finished pellets can be reduced by lowering the addition ratio. If the content of sodium-based bentonite is too high, it will lead to an increase in the alkali metal content of the finished pellets to some extent; if the content of sodium-based bentonite is too low, it may lead to poor subsequent pelletizing results to some extent. Specifically, the content of sodium-based bentonite can be 0.8% by weight, 1.0% by weight, 1.2% by weight, 1.5% by weight, etc.

[0043] In some embodiments, the sodium-based bentonite content is 0.8% to 1.0% by weight.

[0044] In the embodiments of this application, preferably, the content of the sodium-based bentonite is 0.8% to 1.0% by weight.

[0045] In some embodiments, the alkali metal components of the sodium-based bentonite include: K₂O and Na₂O; wherein,

[0046] The K2O content is 0.1% to 0.5% by weight, and the Na2O content is 2.0% to 4.0% by weight.

[0047] In sodium-based bentonite, controlling the K₂O content to 0.1 wt%–0.5 wt% and the Na₂O content to 2.0 wt%–4.0 wt% has the positive effect of reducing the alkali metal content of the finished pellets. Specifically, the K₂O content can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, etc.; specifically, the Na₂O content can be 0.2 wt%, 0.3 wt%, 0.4 wt%, etc.

[0048] In some embodiments, setting the weight of the bentonite according to its type includes:

[0049] If the bentonite is calcium-based bentonite, then the content of calcium-based bentonite is 1.7% to 2.5% by weight.

[0050] The positive effects of controlling the content of calcium-based bentonite to 1.7%–2.5% by weight: Calcium-based bentonite itself contains low alkali metal content, so even a higher addition ratio can still achieve the goal of reducing the alkali metal content in the pellets. If the content of calcium-based bentonite is too high, it will lead to an increase in the alkali metal content of the finished pellets to some extent; if the content of calcium-based bentonite is too low, it may lead to poor subsequent pelletizing effect to some extent. Specifically, the content of calcium-based bentonite can be 1.7% by weight, 1.9% by weight, 2.1% by weight, 2.3% by weight, 2.5% by weight, etc.

[0051] In some embodiments, the content of the calcium-based bentonite is 1.7% to 2.0% by weight.

[0052] In the embodiments of this application, preferably, the content of the above-mentioned calcium-based bentonite is 1.7% to 2.0% by weight.

[0053] In some embodiments, the alkali metal components of the calcium-based bentonite include: K₂O and Na₂O; wherein,

[0054] The K2O content is 0.1% to 0.5% by weight, and the Na2O content is 0.1% to 0.5% by weight.

[0055] In calcium-based bentonite, controlling the K₂O content to 0.1 wt%–0.5 wt% and the Na₂O content to 0.1 wt%–0.5 wt% has the positive effect of reducing the alkali metal content of the finished pellets. Specifically, the K₂O content can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, etc.; and the Na₂O content can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, etc.

[0056] In some embodiments, the alkali metal component of the refined powder includes K2O and Na2O; wherein the K2O content is 0.01% to 0.2% by weight, and the Na2O content is 0.1% to 0.4% by weight.

[0057] The positive effect of controlling the K₂O content to 0.01 wt%–0.2 wt% and the Na₂O content to 0.1 wt%–0.4 wt% in the alkali metal composition of the concentrate is to reduce the alkali metal content of the finished pellets. Specifically, the K₂O content can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, etc.; and the Na₂O content can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, etc.

[0058] In some embodiments, the alkali metal component of the mineral powder includes: K₂O and Na₂O; wherein,

[0059] The K2O content is 0.01% to 0.1% by weight, and the Na2O content is 0.01% to 0.1% by weight.

[0060] The positive effect of controlling the K₂O content to be 0.01 wt% to 0.1 wt% and the Na₂O content to be 0.01 wt% to 0.1 wt% in the alkali metal composition of mineral powder is to reduce the alkali metal content of the finished pellets. Specifically, the K₂O content can be 0.01 wt%, 0.05 wt%, 0.1 wt%, etc.; specifically, the Na₂O content can be 0.01 wt%, 0.05 wt%, 0.1 wt%, etc.

[0061] The preparation method of the above-mentioned low-alkali metal pellets includes: mixing concentrate, mineral powder and bentonite to obtain a mixture; pelletizing the mixture to obtain green pellets; and then roasting the green pellets to obtain finished pellets.

[0062] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0063] Table 1. Composition (wt%) of low-alkali metal pellets

[0064] Serial number Fine powder Mineral powder Sodium bentonite Calcium bentonite Common bentonite Example 1 85 15 0.8 - - Example 2 87 13 1.0 - - Example 3 90 10 - 2.0 - Example 4 92 8 - 1.7 - Example 5 95 5 1.5 - - Example 6 90 10 - 2.5 - Comparative Example 1 93 7 2.3 - - Comparative Example 2 90 10 - - 2.0 Comparative Example 3 87 13 2.0 - - Comparative Example 4 99 1 - 4.0 - Comparative Example 5 97 3 - 3.8 -

[0065] Table 2 Alkali metal composition (wt%) in low-alkali metal pellets

[0066]

[0067]

[0068] As shown in Table 2 above, compared with the total alkali metal content of the pellets obtained in Comparative Examples 1-5 (0.203%, 0.201%, 0.185%, 0.175%, and 0.169%, respectively), Examples 1-6 were implemented using the method of the embodiments of this application. The total alkali metal content of the obtained pellets was less than 0.165%, which was reduced by 0.004% to 0.062% compared with the comparative examples. This indicates that the low alkali metal pellets obtained by the pellet production method of the embodiments of this application effectively control the alkali metal content in the pellets, thereby reducing the alkali metal content in the raw materials fed into the furnace, achieving cost reduction and efficiency improvement. The method is simple and easy to operate and has broad application prospects.

[0069] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A low-alkali metal pellet, characterized in that, The raw materials for the low-alkali metal pellets include: Concentrated flour, mineral powder, and bentonite; among which, The content of the refined powder is 85% to 95% by weight, the content of the mineral powder is 5% to 15% by weight, and the mesh size of the refined powder is below 200 mesh. The bentonite is sodium-based bentonite or calcium-based bentonite; When the bentonite is sodium-based bentonite, its content is 0.8 wt% to 1.5 wt%; the alkali metal components of the sodium-based bentonite include K2O and Na2O; wherein the K2O content is 0.1 wt% to 0.5 wt%, and the Na2O content is 2.0 wt% to 4.0 wt%; When the bentonite is calcium-based bentonite, its content is 1.7% to 2.5% by weight; the alkali metal components of the calcium-based bentonite include K2O and Na2O; wherein the K2O content is 0.1% to 0.5% by weight, and the Na2O content is 0.1% to 0.5% by weight.

2. The low-alkali metal pellets according to claim 1, characterized in that, The content of sodium-based bentonite is 0.8% to 1.0% by weight.

3. The low-alkali metal pellets according to claim 1, characterized in that, The content of the calcium-based bentonite is 1.7% to 2.0% by weight.

4. The low-alkali metal pellets according to claim 1, characterized in that, The alkali metal of the refined powder The components include: K2O and Na2O; among which, The K₂O content is 0.01% to 0.2% by weight, and the Na₂O content is 0.1% to 0.4% by weight. weight%.

5. The low-alkali metal pellets according to claim 1, characterized in that, The alkali metal of the mineral powder The components include: K2O and Na2O; among which, The K₂O content is 0.01% to 0.1% by weight, and the Na₂O content is 0.01% to 0.1% by weight. weight%.

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