Method for using iron ore fines based on blast furnace smelting

Abstract

The application relates to a method for using iron ore powder based on blast furnace smelting. The method is based on scientific classification and mutual matching of the iron ore powder, and uses the blast furnace burden structure, the slag magnesium-aluminum ratio and the sinter basicity and other production core parameters as the basis to calculate the addition amount of dolomite and limestone powder in the sintering process, so as to provide better iron ore powder combination for the blast furnace sintering, and make the utilization of the iron ore powder more economical. The method optimizes the sintering burden scheme from the source, and ensures that the sinter basicity, the slag magnesium-aluminum ratio and other key indexes accurately meet the standards. The core value lies in breaking the limitations of the traditional classification, i.e., qualitative main and fuzzy matching, and realizing the efficient matching of the ore powder and the smelting conditions in a data-based and accurate manner, so as to guarantee the sinter quality stability, optimize the slag metallurgical performance, reduce the smelting energy consumption, and provide solid scientific guidance and technical support for the ore matching optimization, efficient and low-consumption operation of the iron-making production.

Description

Technical Field

[0001] This application relates to the field of iron and steel metallurgy technology, and in particular to a method for using iron ore powder based on blast furnace smelting. Background Technology

[0002] Iron ore powder is a core metallic raw material in blast furnace ironmaking and a crucial basic raw material in sinter production. Currently, the industry's classification and application of iron ore powder are mainly based on loss on ignition, magnetite, hematite, limonite, and siderite. However, in scenarios where blast furnace smelting imposes specific requirements on the furnace charge structure and slag magnesium-aluminum ratio, this traditional classification method is insufficient to clearly define the applicable categories and specific usage conditions of iron ore powder. Furthermore, there is currently a lack of clear standards regarding the classification boundaries and supporting usage conditions for ultra-high alumina iron ore powder, which urgently require further supplementation and improvement.

[0003] In view of this, it is necessary to design a method for using iron ore powder based on blast furnace smelting in order to solve the above problems. Summary of the Invention

[0004] This application provides a method for using iron ore powder based on blast furnace smelting, in order to solve the problems of mismatch between the current iron ore powder classification and usage standards and the actual requirements of blast furnace smelting, and the lack of standards for specific types of iron ore powder, so as to achieve precise alignment between iron ore powder classification and smelting needs. This application provides a method for using iron ore powder based on blast furnace smelting, including the following steps: Obtain production demand parameters at the blast furnace end; Classify the iron ore powder to be used; Based on the blast furnace end production demand parameters, the classified iron ore powders are matched to obtain several sets of mixed iron ore powder data. Based on the blast furnace end production demand parameters and several sets of the mixed iron ore powder to be used, several sets of data on the sinter to be used are obtained. Calculate the cost-effectiveness index of several groups of sinter to be used, and select the optimal group of sinter to be used. The sintered ore from the optimal group is used for blast furnace smelting. The rules for classifying the iron ore powder to be used are as follows: the iron ore powder to be used includes: magnesium-aluminum iron ore powder and silicon-based iron ore powder; The magnesium-aluminum iron ore powder is further divided into: ultra-high aluminum iron ore powder, high aluminum iron ore powder, low magnesium iron ore powder, and high magnesium iron ore powder. The silicon-based iron ore powder is further divided into: low-silicon iron ore powder and high-silicon iron ore powder. The classification rules for the magnesium-aluminum iron ore powder are as follows: When the basicity R of the iron ore powder is greater than the target basicity R of the sinter when the blast furnace end is in stable production over the past period...标 At that time, the iron ore powder was classified as the ultra-high aluminum iron ore powder; When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 And when the Al2O3 content in the iron ore powder is greater than the target Al2O3 content in the sinter when the blast furnace end is in stable production over the past period, the iron ore powder is classified as the high-alumina iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is less than or equal to the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the low-magnesium iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is greater than the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the multi-magnesium iron ore powder. The classification rules for the silicon-based iron ore powder are as follows: When the SiO2 content in the iron ore powder is less than or equal to the target SiO2 content in the sinter when the blast furnace end was in stable production over the past period, the iron ore powder is classified as the low-silicon iron ore powder. When the SiO2 content in the iron ore powder is greater than the target SiO2 content in the sinter when the blast furnace end is in stable production over a past period, the iron ore powder is classified as high-silicon iron ore powder. The iron ore powder is divided into zone one, zone two, zone three, zone four, zone five, and zone six; The first zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the high-silicon iron ore powder. The second zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the low-silicon iron ore powder. The three zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the low-silicon iron ore powder; The four zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the high-silicon iron ore powder; The five zones refer to the iron ore powder belonging to the ultra-high aluminum iron ore powder. The sixth zone refers to the iron ore powder belonging to the polymagnesian iron ore powder.

[0005] In some embodiments, the rules for combining the various iron ore powders to be used are as follows: Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 2; Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 4; Iron ore powder belonging to Zone 1 can be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 2 to be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 1; Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 3. Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 5 and iron ore powder belonging to Zone 6 are used together.

[0006] In some embodiments, the blast furnace end production demand parameters include the target basicity R of sintered ore during stable production at the blast furnace end over a past period. 标 .

[0007] In some embodiments, the blast furnace end production demand parameters also include the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over a past period.

[0008] In some embodiments, acquiring data from several sets of the sinter to be used includes the following steps: Based on the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over the past period, the content of dolomite that needs to be added when the mixed iron ore powder to be used as sinter is determined. Based on the target basicity R of sinter during stable production at the blast furnace end over the past period. 标 Determine the amount of limestone that needs to be added when the mixed iron ore powder to be used as sinter; When the mixed iron ore powder to be used as sinter, the amount of fuel to be added is the weighted average of the fuel added during the stable production of the blast furnace over the past period. Several sets of data for the sinter to be used are obtained from the content of the mixed iron ore powder to be used, the content of the dolomite to be added, the content of the limestone to be added, and the content of the fuel to be added.

[0009] In some embodiments, the method for selecting the sinter to be used in the optimal group includes: among mixed iron ore powders in the same region, the one with the lowest cost-performance ratio index is the most preferred sinter structure.

[0010] In some embodiments, the mixed iron ore powder in the same region is a mixed iron ore powder containing iron ore powder from the same region to be used; the same region includes any one or more of the first region, the second region, the third region, the fourth region, the fifth region, and the sixth region.

[0011] In some embodiments, the formula for calculating the cost-effectiveness index of the sinter to be used is: Cost-effectiveness index = cost per firing / quality per firing.

[0012] In some embodiments, the cost per sinter = unit price of the mixed iron ore powder to be used × mass of the mixed iron ore powder to be used + unit price of limestone × mass of limestone in the sinter to be used + unit price of dolomite × mass of dolomite in the sinter to be used + unit price of fuel × mass of fuel in the sinter to be used.

[0013] Wherein, n is any one of the following materials in the sinter to be used: mixed iron ore powder, dolomite, limestone, and fuel; m n —The quality of the materials; f n —The mass percentage of iron in the material; m 水 —Water quality; I g —The quality of material burn-off; f n — Percentage of iron by mass in the material.

[0014] In some embodiments, the formula for calculating the relationship between Al2O3 and MgO in the sinter during stable production at the blast furnace end over a past period is as follows:

[0015] in, m 1 — The mass of MgO in the sinter during the stable production of the blast furnace end over the past period; m 2—The mass of Al2O3 in the sinter during the stable production of the blast furnace end over the past period; m 总1—The sum of the mass of MgO in other ores and the mass of MgO in fuel when the blast furnace end was in stable production over the past period; m 总2 —The sum of the mass of Al2O3 in other ores and the mass of Al2O3 in fuel when the blast furnace was in stable production over the past period; W 标 —The ratio of MgO to Al2O3 in the slag of the blast furnace during stable production over a past period.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: The iron ore powder utilization method based on blast furnace smelting provided in this application involves the scientific classification and combination of iron ore powders. Based on core production parameters such as blast furnace burden structure, slag magnesium-aluminum ratio, and sinter basicity, the method calculates the addition amounts of dolomite and limestone powder during sintering, providing a higher-quality iron ore powder combination for blast furnace sintering and making iron ore powder utilization more economical. This method optimizes the sintering batching scheme from the source, ensuring that key indicators such as sinter basicity and slag magnesium-aluminum ratio are accurately met. Its core value lies in breaking the limitations of traditional classification methods that are "primarily qualitative and vaguely adaptable," achieving efficient matching of ore powder and smelting conditions through data-driven and precise methods. This ensures the stability of sinter quality, optimizes slag metallurgical properties, and reduces smelting energy consumption, providing solid scientific guidance and technical support for optimized ore blending and efficient, low-consumption operation in ironmaking production. Attached Figure Description

[0017] 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.

[0018] 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.

[0019] Figure 1 This illustration shows a schematic diagram of the classification of magnesium-aluminum iron ore powder in a method for using iron ore powder based on blast furnace smelting provided in this application; Figure 2 This illustration shows a schematic diagram of the classification of silicon-based iron ore powder in a method for using iron ore powder based on blast furnace smelting provided in this application; Figure 3 This paper shows a schematic diagram of the iron ore powder partitioning in a method for using iron ore powder based on blast furnace smelting provided in this application. Detailed Implementation

[0020] 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.

[0021] 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 rigid 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. In addition, whenever a numerical range is indicated in this application, it means including any referenced number (fraction or integer) within the indicated range. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application can be purchased commercially or prepared by existing methods. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in this application, the terms "comprising," "including," etc., mean "including but not limited to." In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this application, "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 application, "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 represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0022] This application provides a method for using iron ore powder based on blast furnace smelting, including the following steps: Step 1: Obtain production demand parameters at the blast furnace end The material information of the blast furnace end during stable production over a past period is statistically analyzed to construct a blast furnace end production status table. The statistical content of the blast furnace end production status table includes: furnace charge structure and its content, chemical composition and its content, blast furnace hot metal composition and its content, and blast furnace hot metal yield. The furnace charge structure includes iron ore powder, other ores, flux I, and fuel I. The composition of the blast furnace hot metal includes one or more of [Fe] content and [Si] content. The other ores include one or more of pellets and lump raw ore. Flux I includes one or more of limestone and dolomite. Fuel I includes one or more of coke, pulverized coal, and coke powder. The sinter is formed by sintering a mixture of iron ore powder, flux, and fuel. Obtain the target basicity R of sinter during stable production at the blast furnace end over a past period. 标 ; Obtain the ratio of Al2O3 to MgO in the slag during stable production at the blast furnace end over a past period. W 标 (generally W 标 =0.4~0.6); to obtain the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over a past period; Step 2: Classify the iron ore powder to be used The rules for classifying iron ore powder for use are as follows: The iron ore powder to be used includes: magnesium-aluminum iron ore powder and silicon iron ore powder; like Figure 1 As shown, the magnesium-aluminum iron ore powder is further divided into: ultra-high aluminum iron ore powder, high aluminum iron ore powder, low magnesium iron ore powder, and high magnesium iron ore powder; like Figure 2 As shown, the silicon-based iron ore powder is further divided into: low-silicon iron ore powder and high-silicon iron ore powder; The classification rules for the magnesium-aluminum iron ore powder are as follows: When the basicity R of the iron ore powder is greater than the target basicity R of the sinter when the blast furnace end is in stable production over the past period... 标 At that time, the iron ore powder was classified as the ultra-high aluminum iron ore powder; When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 And when the Al2O3 content in the iron ore powder is greater than the target Al2O3 content in the sinter when the blast furnace end is in stable production over the past period, the iron ore powder is classified as the high-alumina iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is less than or equal to the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the low-magnesium iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is greater than the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the multi-magnesium iron ore powder. The classification rules for the silicon-based iron ore powder are as follows: When the SiO2 content in the iron ore powder is less than or equal to the target SiO2 content in the sinter when the blast furnace end was in stable production over the past period, the iron ore powder is classified as the low-silicon iron ore powder. When the SiO2 content in the iron ore powder is greater than the target SiO2 content in the sinter when the blast furnace end is in stable production over a past period, the iron ore powder is classified as high-silicon iron ore powder. like Figure 3 As shown, the iron ore powder is divided into zone one, zone two, zone three, zone four, zone five, and zone six; The first zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the high-silicon iron ore powder. The second zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the low-silicon iron ore powder. The three zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the low-silicon iron ore powder; The four zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the high-silicon iron ore powder; The five zones refer to the iron ore powder belonging to the ultra-high aluminum iron ore powder. The sixth zone refers to the iron ore powder belonging to the polymagnesian iron ore powder; Step 3: Obtain data for several sets of mixed iron ore powder to be used. Based on the blast furnace end production demand parameters, the classified iron ore powders are matched to obtain several sets of mixed iron ore powder data. Step 4: Obtain several sets of data for the sinter to be used. Based on the blast furnace end production demand parameters and several sets of the mixed iron ore powder to be used, several sets of data on the sinter to be used are obtained. Step 5: Select the optimal group of sinter to be used. Calculate the cost-effectiveness index of several groups of sinter to be used, and select the optimal group of sinter to be used. Step 6: Use the sinter from the optimal group for blast furnace smelting (ironmaking).

[0023] The iron ore powder utilization method based on blast furnace smelting provided in this application involves the scientific classification and combination of iron ore powders. Based on core production parameters such as blast furnace burden structure, slag magnesium-aluminum ratio, and sinter basicity, the method calculates the amount of dolomite and limestone powder to be added during sintering. This provides a higher-quality iron ore powder combination for blast furnace smelting, making the utilization of iron ore powder more scientific and economical. This method deeply integrates batching calculations with ore powder classification and usage specifications. It not only makes iron ore powder classification more aligned with the actual process requirements of sintering-blast furnace smelting, making the subsequent usage conditions of various ore powders (especially special ores such as ultra-high alumina) clearer and more operable, but also optimizes the sintering batching scheme from the source, ensuring that key indicators such as sinter basicity and slag magnesium-aluminum ratio are accurately met. Its core value lies in breaking the limitations of traditional classification, which is "primarily qualitative and vaguely adaptable." It achieves efficient matching of ore powder and smelting conditions through data-driven and precise methods, thereby ensuring the stability of sinter quality, optimizing the metallurgical performance of slag, and reducing smelting energy consumption. This provides solid scientific guidance and technical support for optimizing ore blending and achieving efficient and low-consumption operation in ironmaking production.

[0024] As an optional implementation, in this embodiment of the application, the rules for combining the various iron ore powders to be used are as follows: Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 2; Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 4; Iron ore powder belonging to Zone 1 can be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 2 to be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 1; Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 3. Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 5 and iron ore powder belonging to Zone 6 are used together.

[0025] Thus, based on the core needs of blast furnace smelting, and using key process conditions such as burden structure, slag magnesium-aluminum ratio, and sinter basicity as classification criteria, a refined classification system of iron ore powder comprising six categories was constructed, clearly defining the suitable scenarios and application schemes for each type of iron ore powder. This classification method effectively overcomes the limitations of traditional classification methods based on burn-off and mineral composition (magnetite, hematite, limonite, siderite) in defining the applicable scope and usage conditions of iron ore powder. Especially for ultra-high alumina iron ore powder, which previously lacked clear standards, it precisely clarifies its classification boundaries and suitable usage specifications, filling relevant application gaps. This provides scientific and precise theoretical support and practical guidance for optimizing iron ore powder blending in blast furnace ironmaking, helping to improve the stability of sinter quality, optimize blast furnace smelting technical indicators, and lay a solid foundation for the efficient, low-consumption, and stable operation of ironmaking production.

[0026] As an optional implementation, in this embodiment of the application, the blast furnace end production demand parameters include the target basicity R of sinter when the blast furnace end is in stable production over a past period. 标 .

[0027] As an optional implementation, in this embodiment of the application, the blast furnace end production demand parameters also include the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over a past period.

[0028] As an optional implementation, in this embodiment of the application, obtaining several sets of data on the sinter to be used includes the following steps: Based on the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over the past period, the content of dolomite II that needs to be added when the mixed iron ore powder to be used as sinter is determined. Based on the target basicity R of sinter during stable production at the blast furnace end over the past period. 标 Determine the content of limestone II that needs to be added when the mixed iron ore powder to be used as sintered ore; When the mixed iron ore powder to be used as sinter, the amount of fuel 2 that needs to be added is the weighted average of the amount of fuel 1 added during the stable production of the blast furnace end in the past period. Several sets of data for the sinter to be used are obtained from the content of the mixed iron ore powder to be used, the content of the dolomite II to be added, the content of the limestone II to be added, and the content of the fuel II to be added.

[0029] A batching table for the sinter to be used can be constructed from several groups of the sinter to be used; the statistical content of the batching table includes: the chemical composition of the materials to be used, the loss on ignition of the materials to be used, and the unit price of the materials to be used; the materials to be used include: iron ore powder (TFe, SiO2, CaO, MgO, Al2O3), flux II, and fuel II; the iron ore powder to be used includes one or more of iron concentrate, PB powder, Mac powder, SP10 powder, FMG mixed powder, and Brazilian mixed powder; flux II includes one or more of dolomite II and limestone II; fuel II includes one or more of coke II, coal powder II, and coke powder II.

[0030] As an optional implementation, in this embodiment of the application, the method for selecting the sinter to be used in the optimal group includes: among mixed iron ore powders in the same region, the one with the lowest cost-effectiveness index is the most preferred sinter structure. The mixed iron ore powders in the same region are mixed iron ore powders containing sinter to be used from the same region; the same region includes any one or more of the following: region one, region two, region three, region four, region five, and region six.

[0031] As an optional implementation, in this embodiment of the application, the formula for calculating the cost-effectiveness index of the sinter to be used is: Cost-effectiveness index = cost per firing / quality per firing; Single sintering cost = unit price of mixed iron ore powder to be used × mass of mixed iron ore powder to be used + unit price of limestone II × mass of limestone II in sinter to be used + unit price of dolomite II × mass of dolomite II in sinter to be used + unit price of fuel II × mass of fuel II in sinter to be used.

[0032] Where, n is any one of the following materials in the sinter to be used: mixed iron ore powder, dolomite II, limestone II, and fuel II. m n —The quality of the materials; f n —The mass percentage of iron in the material; m 水 —Water quality; I g —The quality of material burn-off; f n — Percentage of iron by mass in the material.

[0033] Thus, by using the cost-effectiveness index as the criterion for determining the optimal combination of iron ore powder, the sintering and smelting processes can be optimized at the best cost while meeting the requirements of blast furnace ironmaking.

[0034] As an optional implementation, in this embodiment of the application, the formula for calculating the relationship between Al2O3 and MgO in the sinter during stable production at the blast furnace end over a past period is as follows:

[0035] in, m 1 — The mass of MgO in the sinter during the stable production of the blast furnace end over the past period; m 2—The mass of Al2O3 in the sinter during the stable production of the blast furnace end over the past period; m 总1 —The sum of the mass of MgO in other ores and the mass of MgO in fuel when the blast furnace end was in stable production over the past period; m 总2 —The sum of the mass of Al2O3 in other ores and the mass of Al2O3 in fuel when the blast furnace was in stable production over the past period; W 标 —The ratio of MgO to Al2O3 in the slag of the blast furnace during stable production over a past period.

[0036] Note that limestone includes limestone type I and limestone type II of different qualities; dolomite includes dolomite type I and dolomite type II of different qualities; and fuel includes fuel type I and fuel type II of different qualities.

[0037] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0038] Example 1 Example 1 provides a method for using iron ore powder based on blast furnace smelting, including the following steps: Step 1: Obtain production demand parameters at the blast furnace end Based on the smelting patterns of the blast furnace end, the material information of the blast furnace end during stable production over a past period was statistically analyzed to construct the blast furnace end production status table, the results of which are shown in Tables 1 and 2. The statistical content of the blast furnace end production status table includes: furnace charge structure and its content, chemical composition and its content, composition and content of blast furnace hot metal, and blast furnace hot metal yield. The furnace charge structure includes iron ore powder, other ores, flux I, and fuel I. The composition of the blast furnace hot metal includes the content of [Fe] and [Si]. The other ores include one or more of pellets and lump raw ore. The flux I includes one or more of limestone I and dolomite I. The fuel I includes one or more of coke I, pulverized coal I, and coke powder I. The sintered ore is formed by sintering a mixture of iron ore powder, flux, and fuel. Obtain the target basicity R of sinter during stable production at the blast furnace end over a past period. 标 ; Obtain the ratio of Al2O3 to MgO in the slag during stable production at the blast furnace end over a past period. W 标 (generally W 标 =0.4~0.6); to obtain the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over a past period; The formula for calculating the relationship between Al2O3 and MgO in the sinter during stable production at the blast furnace end over a past period is as follows:

[0039] in, m 1 — The mass of MgO in the sinter during the stable production of the blast furnace end over the past period; m 2—The mass of Al2O3 in the sinter during the stable production of the blast furnace end over the past period; m 总1 —The sum of the mass of MgO in other ores and the mass of MgO in fuel when the blast furnace end was in stable production over the past period; m 总2 —The sum of the mass of Al2O3 in other ores and the mass of Al2O3 in fuel when the blast furnace was in stable production over the past period; W 标 —The ratio of MgO to Al2O3 in the slag of the blast furnace during stable production over a past period.

[0040] Table 1. Production Status of Blast Furnace End During Stable Production in Previous Periods - Burden Structure

[0041] m g = M n × w g , Wherein, n — includes any one of the following materials: iron ore powder, limestone, dolomite, coke, coal powder, coke powder, and other minerals; g —Including any one of the chemical components: Fe, SiO2, CaO, Al2O3, and MgO; m g —The content of each chemical component in the materials of the furnace charge structure; M n — Batch weight, which is the total weight of materials added to the blast furnace in a single batch; w g —— The percentage content of chemical components in a material.

[0042] Table 2 Production Status of Blast Furnace During Stable Production Periods - Smelting Status

[0043] Mass of [Fe] in molten iron:

[0044] Mass of Fe in slag: TFe slag = TFe - TFe molten iron Mass of [Si] in molten iron: ; w [Si] — The percentage content of [Si] in molten iron; Mass of [Si] in slag: Si in slag = total Si Si molten iron Si_total — The total mass of Si in the furnace charge structure; ; w [Fe] —Percentage of [Fe] in molten iron; Batch weight —Mass of molten iron produced from a single batch of furnace charge; ; Batch weight of furnace charge – the weight of a single batch of furnace charge;

[0045]

[0046] ; w [Al2O3] —Percentage content of Al2O3 in the material; ; w [MgO] —Percentage content of MgO in the material; The relationship between MgO and Al2O3 in sintered ore is as follows:

[0047] n—Other ores that were in stable production at the blast furnace end during past periods;

[0048]

[0049] n—any one of the following materials: iron ore powder, dolomite, limestone, or fuel; have to:

[0050] remember: a = target magnesium-aluminum ratio Right now: m 烧MgO =a× m 烧Al2O3 +b w 烧Al2O3 —Percentage content of Al2O3 in sinter; w 烧MgO —Percentage content of MgO in sinter; m 烧Al2O3 —The mass of Al2O3 in the sinter; m 烧MgO —The mass of MgO in the sinter; Step 2: Classify the iron ore powder to be used The rules for classifying iron ore powder for use are as follows: The iron ore powder to be used includes: magnesium-aluminum iron ore powder and silicon iron ore powder; like Figure 1 As shown, the magnesium-aluminum iron ore powder is further divided into: ultra-high aluminum iron ore powder, high aluminum iron ore powder, low magnesium iron ore powder, and high magnesium iron ore powder.

[0051] like Figure 2 As shown, the silicon-based iron ore powder is further divided into: low-silicon iron ore powder and high-silicon iron ore powder; The classification rules for the magnesium-aluminum iron ore powder are as follows: When the basicity R of the iron ore powder is greater than the target basicity R of the sinter when the blast furnace end is in stable production over the past period... 标 At that time, the iron ore powder was classified as the ultra-high aluminum iron ore powder; When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 And when the Al2O3 content in the iron ore powder is greater than the target Al2O3 content in the sinter when the blast furnace end is in stable production over the past period, the iron ore powder is classified as the high-alumina iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is less than or equal to the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the low-magnesium iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is greater than the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the multi-magnesium iron ore powder. The classification rules for the silicon-based iron ore powder are as follows: When the SiO2 content in the iron ore powder is less than or equal to the target SiO2 content in the sinter when the blast furnace end was in stable production over the past period, the iron ore powder is classified as the low-silicon iron ore powder. When the SiO2 content in the iron ore powder is greater than the target SiO2 content in the sinter when the blast furnace end is in stable production over a past period, the iron ore powder is classified as high-silicon iron ore powder. like Figure 3 As shown, the iron ore powder is divided into zone one, zone two, zone three, zone four, zone five, and zone six; The first zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the high-silicon iron ore powder. The second zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the low-silicon iron ore powder. The three zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the low-silicon iron ore powder; The four zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the high-silicon iron ore powder; The five zones refer to the iron ore powder belonging to the ultra-high aluminum iron ore powder. The sixth zone refers to the iron ore powder belonging to the polymagnesian iron ore powder; Step 3: Obtain data for several sets of mixed iron ore powder to be used. Based on the blast furnace end production demand parameters, the classified iron ore powders are matched to obtain several sets of mixed iron ore powder data. The rules for combining the various iron ore powders to be used are as follows: Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 2; Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 4; Iron ore powder belonging to Zone 1 can be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 2 to be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 1; Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 3. Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 5 and iron ore powder belonging to Zone 6 are used together.

[0052] Step 4: Obtain several sets of data for the sinter to be used. Based on the blast furnace production demand parameters and several sets of ready-to-use mixed iron ore powder, several sets of ready-to-use sinter data are obtained, including the following steps: Based on the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over the past period, the content of dolomite II that needs to be added when the mixed iron ore powder to be used as sinter is determined. Based on the target basicity R of sinter during stable production at the blast furnace end over the past period. 标 Determine the content of limestone II that needs to be added when the mixed iron ore powder to be used as sintered ore; When the mixed iron ore powder to be used as sinter, the content of fuel 2 that needs to be added is the weighted average of the amount of fuel 1 added during the stable production of the blast furnace over the past period. Several sets of data for the sinter to be used are obtained from the content of the mixed iron ore powder to be used, the content of the dolomite II to be added, the content of the limestone II to be added, and the content of the fuel II to be added. A batching table for the sinter to be used was then constructed from several groups of sinter to be used, and the results are shown in Table 3. The statistical contents of the batching table for the sinter to be used include: the chemical composition of the materials to be used, the loss on ignition of the materials to be used, and the unit price of the materials to be used. The materials to be used include: iron ore powder (TFe, SiO2, CaO, MgO, Al2O3), flux II, and fuel II. The iron ore powder to be used includes iron concentrate, PB powder, Mac powder, SP10 powder, FMG mixed powder, and Brazilian mixed powder. Flux II includes dolomite II and limestone II. Fuel II includes coke II, coal powder II, and coke powder II. Step 5: Select the optimal group of sinter to be used. Calculate the cost-effectiveness index of several groups of sinter to be used, and select the optimal group of sinter to be used. The formula for calculating the cost-effectiveness index of the sinter to be used is as follows: Cost-effectiveness index = cost per firing / quality per firing; Single sintering cost = unit price of mixed iron ore powder to be used × mass of mixed iron ore powder to be used + unit price of limestone II × mass of limestone II in sinter to be used + unit price of dolomite II × mass of dolomite II in sinter to be used + unit price of fuel II × mass of fuel II in sinter to be used.

[0053] Where, n is any one of the following materials in the sinter to be used: mixed iron ore powder, dolomite II, limestone II, and fuel II. m n —The quality of the materials; f n —The mass percentage of iron in the material; m 水 —Water quality; I g —The quality of material burn-off; f n — Percentage of iron by mass in the material.

[0054] The selection method for the optimal group of sintered ore includes: among mixed iron ore powders in the same region, the one with the lowest cost-effectiveness index is the most preferred sintered ore structure. The mixed iron ore powders in the same region are mixed iron ore powders containing sintered ore powders from the same region; the same region includes any one or more of the following: region one, region two, region three, region four, region five, and region six. Step 6: Use the sinter from the optimal group for blast furnace smelting.

[0055] Table 3. List of raw materials for sinter to be used

[0056] The above method was used to operate an iron smelting plant.

[0057] In the blast furnace charge structure of a certain ironmaking plant, sintered ore accounts for 45.5t / batch, oxide pellets 13.5t / batch, hot-pressed iron blocks 2.0t / batch, coke 12.5t / batch, coke briquettes 1.6t / batch, and pulverized coal 5.9t / batch. The composition of each material (TFe, SiO2, CaO, Al2O3, etc.) is shown in Tables 4-6. The composition, content, and recovery rate of molten iron in the blast furnace are shown in Table 7. It can be seen that the percentage of [Si] in the molten iron is 0.40%, the percentage of [Fe] in the molten iron is 94.8%, the iron element recovery rate (molten iron recovery rate) is 99.50%, the percentage of CaO in the slag is 40.00%, and the required ratio of magnesium oxide to aluminum oxide in the slag is 0.5.

[0058] The iron ore powder in the sinter of this ironmaking plant includes: domestic iron concentrate 1, PB powder, FMG mixed powder, and nickel ore. The basicity R of the sinter is 2.0. Based on the actual conditions of the plant, it is proposed to optimize the ore blending without changing the blast furnace burden structure and the magnesium-aluminum ratio of the slag (0.5). The optimization involves: 1) calculating the impact of current surrounding resources and mainstream iron ore powders on the SiO2 and Al2O3 content of the sinter, clarifying the classification, zoning, and feasibility of each iron ore powder; 2) determining the cost-effectiveness index of each ore powder; and 3) based on the cost-effectiveness index of each iron ore powder, proposing specific optimization suggestions for iron ore blending.

[0059] Table 4 Batch weight, composition and content of various materials in the blast furnace

[0060] Table 5. Unit price, composition, loss on burn, and content of each material

[0061] Table 6 Blast Furnace Batching Table (Composition and Content)

[0062] Table 7 Parameters of Molten Iron and Slag

[0063] The calculated relationship between MgO and Al2O3 in the sinter is: MgO = 0.75% + 0.5 * Al2O3.

[0064] Table 8. Classification results of various iron ore powders to be used

[0065] Suggestion 1: The classification of various iron ore powders is shown in the table. Ultra-high aluminum iron ore powder must be used in combination with high magnesium iron ore powder, and Zone 5 and Zone 6 must be used together. Other ore powders are Zone 1 + Zone 3 + other zones (excluding Zone 5) or Zone 2 + Zone 4 + other zones (excluding Zone 5). That is, nickel ore is used in combination with domestic concentrate 1, domestic concentrate 3 and domestic concentrate 6; FMG mixed powder, printing powder 57, and domestic refined powder 2, domestic refined powder 7, PB powder, Mac powder, bar blend, and card powder can be used together; SP10 powder can be used in combination with domestic refined powder 4, domestic refined powder 5, domestic refined powder 8, and domestic refined powder 9; Recommendation 2: Furthermore, based on the pairing method in suggestion 1, and sorted by cost-effectiveness index within each section, the following pairings are recommended: Nickel ore and domestic concentrate 6; Indian powder 57 and domestic concentrate 7; SP10 powder and domestic concentrate 9; Recommendation 3: Increase the proportion of refined powder by 6 and decrease the proportion of refined powder by 1; or increase the proportion of printing powder by 57 and decrease the proportion of FMG mixed powder; or increase the proportion of refined powder by 9 and decrease the proportion of PB powder.

[0066] This iron ore powder classification method provides guidance on how to mix different ore powders without altering the original furnace charge structure, while also meeting the magnesium-aluminum ratio requirements of the blast furnace slag. Furthermore, according to this method, the proportion of iron ore powder can be dynamically adjusted based on market conditions, thereby reducing costs.

[0067] In summary, this invention provides a method for utilizing iron ore powder in blast furnace smelting. By scientifically classifying and combining iron ore powders, and based on core production parameters such as blast furnace burden structure, slag magnesium-aluminum ratio, and sinter basicity, the method calculates the amount of dolomite and limestone powder to be added during sintering. This provides a higher-quality iron ore powder combination for blast furnace smelting, making iron ore powder utilization more economical. This method optimizes the sintering batching scheme from the source, ensuring that key indicators such as sinter basicity and slag magnesium-aluminum ratio are accurately met. Its core value lies in breaking through the limitations of traditional classification methods that are "primarily qualitative and vaguely adaptable," achieving efficient matching of ore powder and smelting conditions through data-driven and precise methods. This ensures the stability of sinter quality, optimizes slag metallurgical properties, and reduces smelting energy consumption, providing solid scientific guidance and technical support for optimized ore blending and efficient, low-consumption operation in ironmaking production.

[0068] 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 in this application.

Claims

1. A method for using iron ore powder based on blast furnace smelting, characterized in that, Includes the following steps: Obtain production demand parameters at the blast furnace end; Classify the iron ore powder to be used; Based on the blast furnace end production demand parameters, the classified iron ore powders are matched to obtain several sets of mixed iron ore powder data. Based on the blast furnace end production demand parameters and several sets of the mixed iron ore powder to be used, several sets of data on the sinter to be used are obtained. Calculate the cost-effectiveness index of several groups of sinter to be used, and select the optimal group of sinter to be used. The sintered ore from the optimal group is used for blast furnace smelting. The rules for classifying the iron ore powder to be used are as follows: the iron ore powder to be used includes: magnesium-aluminum iron ore powder and silicon-based iron ore powder; The magnesium-aluminum iron ore powder is further divided into: ultra-high aluminum iron ore powder, high aluminum iron ore powder, low magnesium iron ore powder, and high magnesium iron ore powder. The silicon-based iron ore powder is further divided into: low-silicon iron ore powder and high-silicon iron ore powder. The classification rules for the magnesium-aluminum iron ore powder are as follows: When the basicity R of the iron ore powder is greater than the target basicity R of the sinter when the blast furnace end is in stable production over the past period... 标 At that time, the iron ore powder was classified as the ultra-high aluminum iron ore powder; When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 And when the Al2O3 content in the iron ore powder is greater than the target Al2O3 content in the sinter when the blast furnace end is in stable production over the past period, the iron ore powder is classified as the high-alumina iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is less than or equal to the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the low-magnesium iron ore powder. When the basicity R of the iron ore powder is less than or equal to the target basicity R of the sinter when the blast furnace end is in stable production over the past period. 标 When the Al2O3 content in the iron ore powder is less than or equal to the target Al2O3 content in the sinter when the blast furnace end was in stable production over a past period, and when the MgO content in the iron ore powder is greater than the target MgO content in the sinter when the blast furnace end was in stable production over a past period, the iron ore powder is classified as the multi-magnesium iron ore powder. The classification rules for the silicon-based iron ore powder are as follows: When the SiO2 content in the iron ore powder is less than or equal to the target SiO2 content in the sinter when the blast furnace end was in stable production over the past period, the iron ore powder is classified as the low-silicon iron ore powder. When the SiO2 content in the iron ore powder is greater than the target SiO2 content in the sinter when the blast furnace end is in stable production over a past period, the iron ore powder is classified as high-silicon iron ore powder. The iron ore powder is divided into zone one, zone two, zone three, zone four, zone five, and zone six; The first zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the high-silicon iron ore powder. The second zone refers to the iron ore powder that belongs to both the high-alumina iron ore powder and the low-silicon iron ore powder. The three zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the low-silicon iron ore powder; The four zones are: the iron ore powder belongs to both the low-magnesium iron ore powder and the high-silicon iron ore powder; The five zones refer to the iron ore powder belonging to the ultra-high aluminum iron ore powder. The sixth zone refers to the iron ore powder belonging to the polymagnesian iron ore powder.

2. The method for using iron ore powder based on blast furnace smelting according to claim 1, characterized in that, The rules for combining the various iron ore powders to be used are as follows: Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 2; Iron ore powder belonging to Zone 1 to be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 4; Iron ore powder belonging to Zone 1 can be used in combination with iron ore powder belonging to Zone 3 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 2 to be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 1; Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 3. Iron ore powder belonging to Zone 2 can be used in combination with iron ore powder belonging to Zone 4 and iron ore powder belonging to Zone 6. Iron ore powder belonging to Zone 5 and iron ore powder belonging to Zone 6 are used together.

3. The method for using iron ore powder based on blast furnace smelting according to claim 2, characterized in that, The blast furnace end production demand parameters include the target basicity R of sinter when the blast furnace end is in stable production over a past period. 标 .

4. The method for using iron ore powder based on blast furnace smelting according to claim 3, characterized in that, The blast furnace end production demand parameters also include the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over a past period.

5. The method for using iron ore powder based on blast furnace smelting according to claim 3, characterized in that, Obtaining several sets of data for the sinter to be used includes the following steps: Based on the relationship between Al2O3 and MgO in the sinter when the blast furnace end was in stable production over the past period, the content of dolomite that needs to be added when the mixed iron ore powder to be used as sinter is determined. Based on the target basicity R of sinter during stable production at the blast furnace end over the past period. 标 Determine the amount of limestone that needs to be added when the mixed iron ore powder to be used as sinter; When the mixed iron ore powder to be used as sinter, the amount of fuel to be added is the weighted average of the fuel added during the stable production of the blast furnace over the past period. Several sets of data for the sinter to be used are obtained from the content of the mixed iron ore powder to be used, the content of the dolomite to be added, the content of the limestone to be added, and the content of the fuel to be added.

6. The method for using iron ore powder based on blast furnace smelting according to claim 2, characterized in that, The selection method for the optimal group of sintered ore includes: among mixed iron ore powders in the same region, the one with the lowest cost-performance ratio index is the most preferred sintered ore structure.

7. The method for using iron ore powder based on blast furnace smelting according to claim 6, characterized in that, The mixed iron ore powder of the same region refers to the mixed iron ore powder containing iron ore powder of the same region to be used; the same region includes any one or more of the first region, the second region, the third region, the fourth region, the fifth region, and the sixth region.

8. The method for using iron ore powder based on blast furnace smelting according to claim 7, characterized in that, The formula for calculating the cost-effectiveness index of the sinter to be used is as follows: Cost-effectiveness index = cost per firing / quality per firing.

9. The method for using iron ore powder based on blast furnace smelting according to claim 8, characterized in that, Single sintering cost = unit price of mixed iron ore powder to be used × mass of mixed iron ore powder to be used + unit price of limestone × mass of limestone in sinter to be used + unit price of dolomite × mass of dolomite in sinter to be used + unit price of fuel × mass of fuel in sinter to be used. Wherein, n is any one of the following materials in the sinter to be used: mixed iron ore powder, dolomite, limestone, and fuel; m n —The quality of the materials; f n —The mass percentage of iron in the material; m 水 —Water quality; I g —The quality of material burn-off; f n — Percentage of iron by mass in the material.

10. The method for using iron ore powder based on blast furnace smelting according to any one of claims 1 to 9, characterized in that, The formula for calculating the relationship between Al2O3 and MgO in the sinter during stable production at the blast furnace end over a past period is as follows: in, m 1 — The mass of MgO in the sinter during the stable production of the blast furnace end over the past period; m 2—The mass of Al2O3 in the sinter during the stable production of the blast furnace end over the past period; m 总1 —The sum of the mass of MgO in other ores and the mass of MgO in fuel when the blast furnace end was in stable production over the past period; m 总2 —The sum of the mass of Al2O3 in other ores and the mass of Al2O3 in fuel when the blast furnace was in stable production over the past period; W 标 —The ratio of MgO to Al2O3 in the slag of the blast furnace during stable production over a past period.

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