CN115323169B - Pellet ore and preparation method thereof - Google Patents

Pellet ore and preparation method thereof Download PDF

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Publication number
CN115323169B
CN115323169B CN202210923427.3A CN202210923427A CN115323169B CN 115323169 B CN115323169 B CN 115323169B CN 202210923427 A CN202210923427 A CN 202210923427A CN 115323169 B CN115323169 B CN 115323169B
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pellets
flux
pellet
limestone
slaked lime
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CN115323169A (en
Inventor
刘文旺
孙大为
王凯
康海军
纪鹏飞
钱瑞清
耿朝阳
李铮
李铄
李明
董相娟
刘勇君
陈立平
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Shougang Jingtang United Iron and Steel Co Ltd
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Shougang Jingtang United Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/2406—Binding; Briquetting ; Granulating pelletizing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/02—Roasting processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/242—Binding; Briquetting ; Granulating with binders
    • C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/26—Cooling of roasted, sintered, or agglomerated ores
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The application provides pellets and a preparation method thereof, which belong to the technical field of blast furnace burden, wherein the pellets comprise the following components: a flux; concentrate powder; a binder; the flux comprises the following components in parts by mass: 1.5 to 1.9 parts of slaked lime and 0.6 to 1.0 part of limestone. The pellet ore adopts slaked lime as a main material and limestone as an auxiliary material as a mixed flux, and based on raw material conditions, the optimal mixing ratio of the slaked lime and the limestone in the mixed flux is determined to be (1.5-1.9) based on orthogonal experiments, namely (0.6-1.0), so that the whole material of the pellet ore has proper viscosity, good pelletizing performance can be reserved, the bentonite ratio is reduced, the production and quality of the flux pellet ore are prevented from being influenced by excessive viscosity, and meanwhile, the mixed flux releases carbon dioxide through thermal decomposition to adjust the microscopic porosity of the pellet ore, so that the flux pellet ore has proper microscopic porosity, and the requirement of a high-ball blast furnace on the quality of the pellet ore is met.

Description

Pellet ore and preparation method thereof
Technical Field
The application relates to the technical field of blast furnace burden, in particular to pellets and a preparation method thereof.
Background
With the continuous increase of the proportion of pellets in the domestic blast furnace burden structure, the production of high-quality low-silicon flux pellets is urgently needed. The specific surface area of mineral powder for most of domestic pellets is lower than 1000cm 2 About/g, bentonite is more than 1.5% in pellet production process, siO of pellet ore is higher 2 The content is above 4.0%, the grade of the pellet iron is low, and the reduction of the fuel consumption of the blast furnace is not facilitated. The proportion of bentonite must be reduced in producing low-silicon high-grade pellets. Meanwhile, low silicon is unfavorable for controlling the reduction expansion of the pellets, and the control of the reduction expansion of the pellets is also needed to be paid attention to for producing high-quality low-silicon high-grade pellets.
Disclosure of Invention
The embodiment of the application provides pellets and a preparation method thereof, which are used for solving the technical problem that the conventional pellets cannot meet the requirements of a high-ball blast furnace on the quality of the pellets due to the characteristics of proper viscosity, proper micro-porosity and low bentonite consumption.
In a first aspect, embodiments of the present application provide a pellet comprising the following components:
a flux; concentrate powder; a binder;
the flux comprises the following components in parts by mass: 1.5 to 1.9 parts of slaked lime and 0.6 to 1.0 part of limestone.
Further, the mass portion of the concentrate powder is 95.1 to 97.4 portions; the mass portion of the binder is 0.5-1.6 portions.
Further, the slaked lime has a particle size of less than 200 mesh in the slaked lime of > 95% by weight.
Further, in the limestone, the proportion of the limestone with the granularity smaller than 325 meshes is more than 90 percent in terms of weight fraction.
Further, the binder comprises at least one of bentonite and composite bentonite; the concentrate powder comprises iron concentrate powder.
Further, the alkalinity of the pellets is 1.0-1.2; the microscopic porosity of the pellet is 26% -29%.
In a second aspect, an embodiment of the present application provides a method for preparing pellets according to the first aspect, where the method includes:
stirring and mixing the raw materials of all the components to obtain a premix;
pelletizing the premix, and screening to obtain green pellets;
and drying, preheating, roasting and cooling the green pellets to obtain pellets.
Further, the pelletizing of the premix and the sieving are carried out to obtain green pellets, which comprises the following steps:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and sieving to obtain green pellets with the granularity of 8-16 mm.
Further, the preheated process parameters include: the temperature is 650-1100 ℃ and the duration is 6-7.5 min.
Further, the process parameters of the roasting include: the temperature is 1200-1280 ℃ and the duration is 8.3-10.6 min.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the embodiment of the application provides pellets, which adopt slaked lime as a main material and limestone as an auxiliary material as a mixed flux, and based on raw material conditions, the optimal mixing ratio of the slaked lime and the limestone in the mixed flux is determined to be (1.5-1.9) (0.6-1.0), so that the whole material of the pellets has proper viscosity, good pelletizing performance can be kept, bentonite ratio is reduced, and the production and quality of the flux pellets are prevented from being influenced by excessive viscosity, and meanwhile, the mixed flux releases carbon dioxide through thermal decomposition reaction to adjust the microscopic porosity of the pellets, so that the flux pellets have proper microscopic porosity, stress concentration during reduction expansion can be relieved, reduction expansion effect is reduced mechanically, and the existing pellets have the characteristics of proper viscosity, proper microscopic porosity and low bentonite consumption, thereby effectively avoiding the problems of excessive adhesion of the mixture caused by single-matched slaked lime and high grade and low quality of the pellets caused by excessive bentonite addition when single-matched limestone powder, and meeting the requirements of high-grade pellet furnaces on the high quality of the high-grade pellets.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic flow chart of a method for preparing pellets according to an embodiment of the present application;
FIG. 2 is a flow chart of a preparation process of pellets provided by the embodiment of the application;
FIG. 3 is a diagram of a reduction expansion tank of pellets with different flux ratios in the embodiment of the application;
fig. 4 is a temperature optimization comparison chart of the flux proportioning and shaping process in the embodiment of the application.
Detailed Description
The advantages and various effects of the present application will be more clearly apparent from the following detailed description and examples. It will be understood by those skilled in the art that these specific embodiments and examples are intended to illustrate the application, not to limit the application.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In case of conflict, the present specification will control.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
With the continuous increase of the proportion of pellets in the domestic blast furnace burden structure, the production of high-quality low-silicon flux pellets is urgently needed. The specific surface area of mineral powder for most of domestic pellets is lower than 1000cm 2 About/g, bentonite is more than 1.5% in pellet production process, siO of pellet ore is higher 2 The content is above 4.0%, the grade of the pellet iron is low, and the reduction of the fuel consumption of the blast furnace is not facilitated. The proportion of bentonite must be reduced in producing low-silicon high-grade pellets. Meanwhile, low silicon is unfavorable for controlling the reduction expansion of the pellets, and the control of the reduction expansion of the pellets is also needed to be paid attention to for producing high-quality low-silicon high-grade pellets.
The technical scheme provided by the embodiment of the application aims to solve the technical problems, and the overall thought is as follows:
in a first aspect, embodiments of the present application provide a pellet comprising the following components:
a flux; concentrate powder; a binder;
the flux comprises the following components in parts by mass: 1.5 to 1.9 parts of slaked lime and 0.6 to 1.0 part of limestone.
The embodiment of the application provides pellets, which adopt slaked lime as a main material and limestone as an auxiliary material as a mixed flux, and based on raw material conditions, the optimal mixing ratio of the slaked lime and the limestone in the mixed flux is determined to be (1.5-1.9) (0.6-1.0), so that the whole material of the pellets has proper viscosity, good pelletizing performance can be kept, bentonite ratio is reduced, and the production and quality of the flux pellets are prevented from being influenced by excessive viscosity, and meanwhile, the mixed flux releases carbon dioxide through thermal decomposition reaction to adjust the microscopic porosity of the pellets, so that the flux pellets have proper microscopic porosity, stress concentration during reduction expansion can be relieved, reduction expansion effect is reduced mechanically, and the existing pellets have the characteristics of proper viscosity, proper microscopic porosity and low bentonite consumption, thereby effectively avoiding the problems of excessive adhesion of the mixture caused by single-matched slaked lime and high grade and low quality of the pellets caused by excessive bentonite addition when single-matched limestone powder, and meeting the requirements of high-grade pellet furnaces on the high quality of the high-grade pellets.
In the application, the flux can promote the melting of concentrate powder in the preparation process of pellets, and more importantly, the flux is used for controlling the alkalinity of the pellets to be 1.1+/-0.1, controlling the viscosity of the pelletizing materials to be proper and controlling the micro-porosity of the pellets to be proper.
In the present application, a binder is used to bind the pellet fine powder and the flux into pellets.
In the application, the concentrate powder can be selected from commercial products commonly used in the field, such as iron concentrate powder and the like.
As an implementation mode of the embodiment of the application, the mass portion of the concentrate powder is 95.1-97.4 portions; the mass portion of the binder is 0.5-1.6 portions.
In the application, the reasons for controlling 1.5-1.9 parts of slaked lime, 0.6-1.0 parts of limestone, 95.1-97.4 parts of pellet fine powder and 0.5-1.6 parts of binder are as follows: the optimum proportion of the flux is determined by an orthogonal experiment method, the viscosity of the mixture is optimum, the proportion of bentonite is reduced, and the proper microscopic porosity of the pellets is provided, so that the low-silicon flux pellets with excellent performance can be produced and prepared.
As an embodiment of the present example, the slaked lime has a particle size of less than 200 mesh in the slaked lime of > 95% by weight.
As an implementation of the embodiment of the application, the limestone has a particle size of less than 325 mesh and accounts for > 90% of the limestone in weight fraction.
In the application, the slaked lime with granularity smaller than 200 meshes is controlled to account for more than 95% of the whole slaked lime; the reason why the limestone with the granularity smaller than 325 meshes accounts for more than 90% of the whole limestone is that: the specific surface area of the two fluxes is increased, the pelletizing performance is enhanced, the adverse effect of the excessively small ratio is that the pelletizing process is adverse, the bentonite proportion is increased, the material balling performance is poor, and the compressive strength of the finished pellets is reduced.
As an implementation of the embodiment of the present application, the binder includes at least one of bentonite and composite bentonite; the concentrate powder comprises iron concentrate powder.
In the present application, the binder includes, but is not limited to: at least one of bentonite and composite bentonite; the binder has the functions of improving the balling performance of the pellet mixture to improve the pellet green ball index and the metallurgical performance, the principle of controlling the dosage of the binder is to reduce the gangue carrying-in as much as possible on the premise of ensuring the pellet green ball strength, and the adverse effect of overlarge weight part is the gangue content SiO in the pellet ore 2 The adverse effect of the increase and the undersize is that the balling is difficult, the green pellet strength is low, and the pellet quality is poor.
In the present application, the composite bentonite specifically refers to bentonite added with an organic binder.
As an implementation mode of the embodiment of the application, the alkalinity of the pellets is 1.0-1.2; the microscopic porosity of the pellet is 26% -29%.
In a second aspect, an embodiment of the present application provides a method for preparing pellets according to the first aspect, as shown in fig. 1, where the method includes:
stirring and mixing the raw materials of all the components to obtain a premix;
pelletizing the premix, and screening to obtain green pellets;
and drying, preheating, roasting and cooling the green pellets to obtain pellets.
The embodiment of the application provides a preparation method of pellets, which does not need extra specific equipment, is simple to operate, can be produced in batches, and meets the quality requirement of pellets with a high charging ratio.
As an implementation mode of the embodiment of the application, the pelletizing of the premix and the sieving are carried out to obtain green pellets, and the method specifically comprises the following steps:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and sieving to obtain green pellets with the granularity of 8-16 mm.
In the application, 7.8-8.8 parts by weight of water is added into the mixture to make balls, and green balls are obtained, wherein the granularity of the green balls is 8-16 mm because: the limestone powder has strong water absorption and poor balling property, the slaked lime powder has good balling property, and the two fluxes are mixed for use, so that the weight of added water is moderately increased to meet the balling requirement; in order to meet the air permeability requirement of roasting, green pellets are screened, qualified green pellets are screened out and subjected to the next step, unqualified green pellets are returned, and pelletizing is performed again; of course, other suitable particle sizes may be used.
As an implementation manner of the embodiment of the present application, the preheating process parameters include: the temperature is 650-1100 ℃ and the duration is 6-7.5 min.
In the application, the preheating temperature is controlled to be 650-1100 ℃, and the preheating time is 6min-7.5m because: the decomposition reaction of the compounds such as crystal water decomposition and evaporation is guaranteed to be full, the addition of limestone powder needs to guarantee a moderately high preheating temperature and full preheating practice, the pyrolysis reaction of the limestone powder is guaranteed to be full, and the micro porosity of the flux pellets is regulated.
As an implementation manner of the embodiment of the present application, the process parameters of roasting include: the temperature is 1200-1280 ℃ and the duration is 8.3-10.6 min.
In the application, the roasting temperature is controlled to be 1200-1280 ℃, and the roasting time is 8.3-10.6 min because: after limestone powder is added, the porosity of the flux balls is increased, and the temperature in the roasting system is reduced due to the decomposition and heat absorption of the limestone powder, which is unfavorable for controlling the strength of the pellets, moderately improves the roasting temperature and prolongs the roasting time, and ensures that the iron oxide is fully oxidized and forms firm Fe 2 O 3 Recrystallization bonds strengthen the formation of secondary hematite, thereby strengthening Fe 2 O 3 And (5) recrystallization consolidation.
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
Test examples
According to the embodiment of the pellet of the first aspect, the present example provides a method for determining the optimum proportion of flux by orthogonal experiment, as shown in fig. 3, the method comprising the steps of: according to the alkalinity requirement (R=1.1) of the flux pellets, carrying out batching measurement and calculation according to the existing raw material conditions (Peru powder and Hainan powder), completing a batching base test table on the premise of meeting the batching component requirement, and carrying out various proportioning pelleting tests according to a small pelleting disc of a laboratory, wherein 4 batching schemes are preferably selected (test proportioning 1-4; the experimental proportion 1 comprises Peruvian powder, namely, hainan powder=91.5:4.8, externally-compounded bentonite 1.05%, slaked lime 2.15% and limestone 0.3%, the experimental proportion 2 comprises Peruvian powder, namely, hainan powder=91.5:4.8, externally-compounded bentonite 1.05%, slaked lime 1.95% and limestone 0.6%, the experimental proportion 3 comprises Peruvian powder, namely, hainan powder=91.5:4.8, externally-compounded bentonite 1.05%, slaked lime 1.75% and limestone 0.85%, the experimental proportion 4 comprises Peruvian powder, hainan powder=91.5:4.8, externally-compounded bentonite 1.05%, slaked lime 1.55% and limestone 1.15%, the proportion of the main raw materials of the Peruvian powder, hainan powder and bentonite binder is basically unchanged, the proportion is changed into the mixture to replace a certain amount of slaked lime, and the comparative analysis consumption is carried out, wherein the preferable standard of the mixture has proper viscosity, good sphericity, high green ball strength and the like, and the slaked lime is only used as a solvent in the experimental scheme: peru powder: southwest flour=91.5:4.8; 1.05% of externally-matched bentonite and 2.35% of slaked lime; limestone refers to limestone alone as a flux: peru powder: southwest flour=91.5:4.8; 1.05 percent of externally-matched bentonite and 3.35 percent of limestone. The two proportioning schemes are the original proportioning modes and are used as test comparison. The above proportions are subjected to repeated laboratory tests (the technological parameters are fixed and the original slaked lime production parameters), and the test proportion 3 is selected to be optimal (Peruvian powder: hainan powder=91.5:4.8; externally compounded bentonite 1.05%, slaked lime 1.75% and limestone 0.85%).
According to the embodiment of the pellet preparation method of the second aspect, the thermal technology is optimized based on the optimal flux ratio of the orthogonal experiment, as shown in fig. 4, according to the heat consumption characteristics of thermal decomposition (825-896 ℃) of limestone powder, the temperature is properly increased in the early stage of preheating, and the roasting temperature is increased in the later stage, so that the problem of slightly lower strength of the limestone powder for matching is overcome. Examples flux pellets produced to achieve the desired effect: the components are unchanged, the reduction expansion is reduced, and the cost is optimized.
Example 1
The example provides a pellet, the preparation process of which is shown in figure 2, and specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, limestone, slaked lime and a binder according to the mass requirement of the pellets; 0.85 parts of limestone, 1.75 parts of slaked lime, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.05 parts of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: and (3) putting the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting. The drying temperature is 390 ℃ and the drying time is 7.2min; the preheating temperature is 650-1100 ℃ and the preheating time is 7min; the roasting temperature is 1250 ℃ and the roasting time is 9.8min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The basicity of the pellets obtained in this example was 1.10; the microscopic porosity of the pellets was 27.15%.
Example 2
The embodiment of the present application is different from embodiment 1 in that: reducing the limestone proportion and improving the lime hydrate proportion. The method specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, limestone, slaked lime and a binder according to the mass requirement of the pellets; 0.6 part of limestone, 2 parts of slaked lime, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.05 parts of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: placing qualified green pellets with the diameter of 8mm-16mm into a belt roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting; the drying temperature is 360 ℃ and the drying time is 7min; the preheating temperature is 650-1050 ℃, and the preheating time is 6.7min; roasting temperature is 1240 ℃ and roasting time is 9.5min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The basicity of the pellets obtained in this example was 1.11; the microscopic porosity of the pellets was 26.95%.
Comparative example 1
The comparative example 1 of the present application differs from example 1 in that: lime stone is stopped, and only slaked lime is added as flux. The method specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, slaked lime and a binder according to the mass requirement of the pellets; 2.6 parts of slaked lime, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 0.97 part of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: placing qualified green pellets with the diameter of 8mm-16mm into a belt roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting; the drying temperature is 330 ℃, and the drying time is 6.7min; the preheating temperature is 550-1050 ℃, and the preheating time is 6.5min; the roasting temperature is 1230 ℃, and the roasting time is 9.5min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The basicity of the pellets obtained in this example was 1.10; the microscopic porosity of the pellets was 23.9%.
Comparative example 2
Comparative example 2 of the present application differs from example 1 in that: small amount of limestone is added, the proportion of the limestone is 0.3 percent, and the slaked lime is taken as a main flux. The method specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, limestone, slaked lime and a binder according to the mass requirement of the pellets; 0.3 part of limestone, 2.3 parts of slaked lime, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.02 parts of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: placing qualified green pellets with the diameter of 8mm-16mm into a belt roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting; the drying temperature is 390 ℃ and the drying time is 7.2min; the preheating temperature is 650-1100 ℃ and the preheating time is 7min; the roasting temperature is 1250 ℃ and the roasting time is 9.8min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The basicity of the pellets obtained in this example was 1.11; the micro porosity of the pellets was 25.76%.
Comparative example 3
Comparative example 3 of the present application differs from example 1 in that: adding a small amount of slaked lime, wherein the proportion of slaked lime is 0.6%, and limestone is used as a main flux; the method specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, limestone, slaked lime and a binder according to the mass requirement of the pellets; 2.15 parts of limestone, 0.6 part of slaked lime, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.3 parts of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: placing qualified green pellets with the diameter of 8mm-16mm into a belt roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting; the drying temperature is 450 ℃, and the drying time is 7.5min; the preheating temperature is 650-1150 ℃ and the preheating time is 7.5min; roasting temperature is 1280 ℃, and roasting time is 10.5min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The alkalinity of the pellets obtained in this example was 1.12; the microscopic porosity of the pellets was 32%.
Comparative example 4
Comparative example 4 of the present application differs from example 1 in that: lime hydrate is stopped and limestone is used as flux. The method specifically comprises the following steps:
the first step: and (3) batching: mixing iron concentrate powder, limestone and binder according to the mass requirement of the pellets; 4.3 parts of limestone, 91.5 parts of Peruvian iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.55 parts of calcium bentonite;
and a second step of: mixing evenly: fully and uniformly mixing various pellet refined powders, flux and binder;
and a third step of: pelletizing: adding proper water to a disc pelletizer for pelletizing, and controlling the water content to be 8.3+/-0.5%;
fourth step: screening green balls: screening qualified green pellets with the granularity of 8-16 mm by using a double-layer rolling screen;
fifth step: and (3) putting the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine by utilizing a shuttle type material distributor for drying, preheating and roasting. The drying temperature is 450 ℃, and the drying time is 7.8min; the preheating temperature is 650-1150 ℃ and the preheating time is 7.5min; roasting temperature is 1280 ℃, and roasting time is 10.8min; soaking temperature is 1150 ℃, and soaking time is 3min;
sixth step: and (3) ball forming and cooling: cooling to below 120 ℃ in a cooling section of the belt roasting machine.
The alkalinity of the pellets obtained in this example was 1.12; the micro porosity of the pellets was 32.27%.
The composition ratios of the above examples 1-2 and comparative examples 1-4 are shown in Table 1, and the composition and performance parameters of the finished pellets are shown in Table 2.
Table 1 examples and comparative examples proportioning table
Sequence number Peruvian powder Hainan powder Slaked lime Limestone powder Bentonite clay
Example 1 91.5 4.8 1.75 0.85 1.05
Example 2 91.5 4.8 2.0 0.6 1.05
Comparative example 1 91.5 4.8 2.6 0.97
Comparative example 2 91.5 4.8 2.3 0.3 1.02
Comparative example 3 91.5 4.8 0.6 2.15 1.3
Comparative example 4 91.5 4.8 4.3 1.55
Table 2 example and comparative example finished pellet composition and performance parameters
Sequence number TFe％ SiO 2 ％ CaO％ Alkalinity% Compressive Strength Reduction expansion%
Example 1 65.41 2.19 2.42 1.10 3251 15.6
Example 2 65.44 2.19 2.44 1.11 3289 15.9
Comparative example 1 65.55 2.16 2.38 1.10 3327 17.5
Comparative example 2 65.49 2.17 2.41 1.11 3339 17.2
Comparative example 3 64.96 2.27 2.54 1.12 3022 16.7
Comparative example 4 64.17 2.38 2.67 1.12 2957 16.3
As can be seen from the above tables 1 and 2, the pellets prepared by the proportion and method provided by the embodiment of the application are mixed with a proper proportion of mixed flux, and the compressive strength of the pellets is stable and can be kept above 3200N/p; the pellet silicon has low grade and high grade, silicon is about 2.2 percent, and the grade is more than 65 percent; the reduction expansion is as low as 15.6%, which is obtained by comparing the data of the comparative example and the data of the example, and only lime hydrate is added as the flux, or the amount of limestone is too small, the micro porosity of the flux pellet is poor, and the reduction expansion is higher than 17%; and the lime hydrate is added in a large amount, so that the viscosity of the mixture is high, the production stability is frequently influenced by the bonding of a production system, the quality of green pellets is poor, and the pellets are seriously deformed. Only limestone is added as flux, or the amount of lime hydrate is too small, the balling performance of the mixture is poor, the proportion of bentonite is increased, the silicon of the pellets reaches about 3%, and the taste is reduced to below 65%; and the limestone has large proportion and too many pores of the pellets, which is not beneficial to controlling the pellet strength, and the pellet compression resistance is reduced to below 3000N/p.
In summary, the embodiment of the application provides a pellet and a preparation method thereof, and the flux adding method of the flux pellet is optimized, slaked lime is used as a main component, and limestone is used as an auxiliary component, so that the optimal viscosity of the flux is flexibly adjusted, the bentonite proportion is reduced, the influence of excessive flux viscosity on material transportation and pelletizing is avoided, and the microscopic porosity of the pellet is improved. The method can produce the low-silicon low-expansion high-quality flux pellets, effectively meets the requirements of a high-pellet blast furnace on the quality of the pellets, is beneficial to the green development of the steel industry, and has remarkable social and economic benefits.
It should be understood that the endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and that the range or value is to be understood as encompassing values close to the range or value. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, the term "and/or" appearing herein is merely an association relationship describing the associated object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A pellet, characterized in that the pellet is composed of the following components:
a flux; concentrate powder; a binder;
the weight portion of the concentrate powder is 95.1 to 97.4 portions; the mass portion of the binder is 0.5-1.6 portions, and the flux comprises: 1.5 to 1.9 parts of slaked lime and 0.6 to 1.0 part of limestone; the binder comprises at least one of bentonite and composite bentonite, wherein the proportion of the slaked lime with the granularity smaller than 200 meshes is more than 95%, the proportion of the limestone with the granularity smaller than 325 meshes is more than 90%, and the alkalinity of the pellet ore is 1.0-1.2; the microscopic porosity of the pellet is 26% -29%, the preparation method of the pellet comprises the steps of drying, preheating, roasting and cooling raw pellets to obtain the pellet, and the preheating process parameters comprise: the temperature is 650-1100 ℃ and the duration is 6-7.5 min, and the roasting process parameters comprise: the temperature is 1200-1280 ℃ and the duration is 8.3-10.6 min.
2. The pellet of claim 1, wherein the concentrate powder comprises iron concentrate powder.
3. A method of producing pellets as claimed in any of claims 1 to 2, comprising:
stirring and mixing the raw materials of all the components to obtain a premix;
pelletizing the premix, and screening to obtain green pellets;
and drying, preheating, roasting and cooling the green pellets to obtain pellets.
4. The method for preparing pellets according to claim 3, wherein the pelletizing of the premix and the post-sieving to obtain green pellets comprises:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and sieving to obtain green pellets with the granularity of 8-16 mm.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1804058A (en) * 2006-01-10 2006-07-19 许贵宾 Method for making fluxed iron ore powder composite pellet
CN108998660A (en) * 2018-09-30 2018-12-14 四川德胜集团钒钛有限公司 A kind of vanadium ilmenite concentrate powder deep-bed sintering technique
CN113186391A (en) * 2021-04-01 2021-07-30 首钢京唐钢铁联合有限责任公司 Pellet and preparation method thereof
WO2021197258A1 (en) * 2020-03-30 2021-10-07 中南大学 Oxidized pellet binding agent made from low-rank coal, preparation method for same, and applications thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1804058A (en) * 2006-01-10 2006-07-19 许贵宾 Method for making fluxed iron ore powder composite pellet
CN108998660A (en) * 2018-09-30 2018-12-14 四川德胜集团钒钛有限公司 A kind of vanadium ilmenite concentrate powder deep-bed sintering technique
WO2021197258A1 (en) * 2020-03-30 2021-10-07 中南大学 Oxidized pellet binding agent made from low-rank coal, preparation method for same, and applications thereof
CN113186391A (en) * 2021-04-01 2021-07-30 首钢京唐钢铁联合有限责任公司 Pellet and preparation method thereof

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