CN115323169A - Pellet and preparation method thereof - Google Patents
Pellet and preparation method thereof Download PDFInfo
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- CN115323169A CN115323169A CN202210923427.3A CN202210923427A CN115323169A CN 115323169 A CN115323169 A CN 115323169A CN 202210923427 A CN202210923427 A CN 202210923427A CN 115323169 A CN115323169 A CN 115323169A
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- pellet
- pellets
- limestone
- flux
- slaked lime
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- 239000008188 pellet Substances 0.000 title claims abstract description 165
- 238000002360 preparation method Methods 0.000 title abstract description 11
- 239000000843 powder Substances 0.000 claims abstract description 65
- 235000019738 Limestone Nutrition 0.000 claims abstract description 53
- 239000006028 limestone Substances 0.000 claims abstract description 53
- 230000004907 flux Effects 0.000 claims abstract description 47
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 44
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 43
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 43
- 235000011116 calcium hydroxide Nutrition 0.000 claims abstract description 43
- 238000005453 pelletization Methods 0.000 claims abstract description 31
- 229910000278 bentonite Inorganic materials 0.000 claims abstract description 30
- 239000000440 bentonite Substances 0.000 claims abstract description 30
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000011230 binding agent Substances 0.000 claims abstract description 28
- 238000002156 mixing Methods 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 15
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 8
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 3
- 235000010755 mineral Nutrition 0.000 claims abstract description 3
- 239000011707 mineral Substances 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 50
- 239000012141 concentrate Substances 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 31
- 229910052742 iron Inorganic materials 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 21
- 238000001035 drying Methods 0.000 claims description 21
- 238000012216 screening Methods 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 7
- 239000002131 composite material Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 22
- 238000002474 experimental method Methods 0.000 abstract description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract description 6
- 238000005979 thermal decomposition reaction Methods 0.000 abstract description 4
- 239000001569 carbon dioxide Substances 0.000 abstract description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 20
- 229910052710 silicon Inorganic materials 0.000 description 15
- 239000010703 silicon Substances 0.000 description 15
- 230000009467 reduction Effects 0.000 description 13
- 239000000203 mixture Substances 0.000 description 11
- 238000002791 soaking Methods 0.000 description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 9
- 229910000281 calcium bentonite Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 230000002411 adverse Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000011863 silicon-based powder Substances 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000013142 basic testing Methods 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical group [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
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Classifications
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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)
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- Mechanical Engineering (AREA)
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- Inorganic Chemistry (AREA)
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Abstract
The invention provides a pellet and a preparation method thereof, belonging to the technical field of blast furnace burden, wherein the pellet comprises the following components: fusing agent; fine mineral powder; and a binder; the flux comprises the following components in parts by mass: 1.5 to 1.9 portions of slaked lime and 0.6 to 1.0 portion of limestone. The pellet adopts slaked lime as a main material and limestone as an auxiliary material as a mixed flux, and the optimal mixing ratio of slaked lime and limestone in the mixed flux is determined to be (1.5-1.9) to (0.6-1.0) by an orthogonal experiment based on raw material conditions, so that the whole material of the pellet has proper viscosity, good pelletizing performance can be kept, the ratio of bentonite is reduced, the influence of overlarge viscosity on the production and quality of the flux pellets is avoided, and meanwhile, the mixed flux releases carbon dioxide through sending thermal decomposition to adjust the micro porosity of the pellet, so that the flux pellets have proper micro porosity, and the requirement of a high-sphericity ratio furnace on the quality of the pellet is met.
Description
Technical Field
The application relates to the technical field of blast furnace burden, in particular to pellet and a preparation method thereof.
Background
With the continuous improvement of the proportion of pellets in the charging material structure of the domestic blast furnace, the production of high-quality low-silicon fusing agent pellets is urgently needed. The specific surface area of most of the domestic ore powder for pelletizing is lower than 1000cm 2 About/g, the proportion of bentonite is higher than 1.5% in the pellet production process, and the SiO content of the pellets is higher 2 The content is more than 4.0 percent, the pellet iron has low taste, and is not beneficial to reducing the fuel consumption of a blast furnace. The proportion of bentonite must be reduced for producing the low-silicon high-grade pellet. Meanwhile, the low silicon is unfavorable for controlling the reduction and expansion of the pellets, so that the high-quality low-silicon high-grade pellet ore is produced, and the control of the reduction and expansion of the pellets needs to be paid attention to.
Disclosure of Invention
The embodiment of the application provides a pellet and a preparation method thereof, and aims to solve the technical problem that the requirement of a high-sphericity ratio furnace on the quality of the pellet cannot be met due to the fact that the conventional pellet cannot have the characteristics of proper viscosity, proper micro-porosity and low bentonite consumption.
In a first aspect, the present application provides a pellet, which includes the following components:
fusing agent; fine mineral powder; and a binder;
the flux comprises the following components in parts by mass: 1.5 to 1.9 portions of slaked lime and 0.6 to 1.0 portion of limestone.
Further, the mass portion of the concentrate powder is 95.1-97.4; the mass portion of the binder is 0.5-1.6.
Further, the ratio of the slaked lime with the particle size of less than 200 meshes in the slaked lime is more than 95 percent by weight.
Further, in the limestone, the proportion of limestone with the granularity smaller than 325 meshes is more than 90 percent.
Further, the binder comprises at least one of bentonite and composite bentonite; the concentrate powder includes iron concentrate powder.
Further, the alkalinity of the pellet is 1.0-1.2; the micro porosity of the pellet is 26-29%.
In a second aspect, 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 each component to obtain a premix;
pelletizing the premix, and then screening to obtain green pellets;
and drying, preheating, roasting and cooling the green pellets to obtain pellets.
Further, pelletizing the premix, and then screening to obtain green pellets, specifically comprising:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and then screening to obtain green pellets with the granularity of 8-16 mm.
Further, the preheated process parameters include: the temperature is 650-1100 ℃, and the time duration is 6-7.5 min.
Further, the roasting process parameters comprise: the temperature is 1200-1280 ℃, and the time 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 a pellet, the pellet adopts slaked lime as a main material and limestone as an auxiliary material, the optimal mixing ratio of slaked lime and limestone in the mixed flux is determined to be (1.5-1.9) to (0.6-1.0) by an orthogonal experiment based on raw material conditions, so that the whole material of the pellet has proper viscosity, good pelletizing performance can be kept, the proportioning of bentonite is reduced, the influence of overlarge viscosity on the production and quality of the flux pellet is avoided, simultaneously, the mixed flux releases carbon dioxide through thermal decomposition reaction to adjust the micro porosity of the pellet, the flux pellet has proper micro porosity, the stress concentration during the reduction expansion period of the flux pellet can be relieved, the effect of reducing the reduction expansion is realized in the mechanism, the existing pellet has the characteristics of proper viscosity, proper micro porosity and low bentonite dosage, the problem of the over-adhesion of the mixed material and the problem of high-grade silicon low-grade powder caused by the overlarge dosage of the bentonite when the limestone is singly matched with the slaked lime are effectively avoided, and the requirement of high quality ratio of the high-grade silicon powder of the pellet on the high-grade pellet is met.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic flow chart of a pellet ore manufacturing method provided in an embodiment of the present application;
fig. 2 is a flowchart of a pellet ore manufacturing process according to an embodiment of the present disclosure;
FIG. 3 is a diagram of reduction expansion boxes of pellets of different flux ratios in the example of the present application;
fig. 4 is a comparison graph of optimization of process temperature in flux proportioning sizing in the embodiment of the present application.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings 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 invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
With the continuous improvement of the proportion of pellets in the charging material structure of the domestic blast furnace, the production of high-quality low-silicon fusing agent pellets is urgently needed. The specific surface area of most of the domestic ore powder for pelletizing is lower than 1000cm 2 About/g, the proportion of bentonite is higher than 1.5% in the pellet production process, and the SiO content of the pellets is higher 2 The content is more than 4.0 percent, the pellet iron has low taste, and is not beneficial to reducing the fuel consumption of a blast furnace. The proportion of bentonite must be reduced for producing the low-silicon high-grade pellet. Meanwhile, the low silicon is unfavorable for controlling the reduction and expansion of the pellets, and the control of the reduction and expansion of the pellets is required to be paid attention to the production of high-quality low-silicon high-grade pellets.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
in a first aspect, embodiments of the present application provide a pellet, where the pellet includes the following components:
fusing agent; concentrate powder; and a binder;
the flux comprises the following components in parts by mass: 1.5 to 1.9 portions of slaked lime and 0.6 to 1.0 portion of limestone.
The embodiment of the application provides a pellet, the pellet adopts slaked lime as a main material and limestone as an auxiliary material, the optimal mixing ratio of slaked lime and limestone in the mixed flux is determined to be (1.5-1.9) to (0.6-1.0) by an orthogonal experiment based on raw material conditions, so that the whole material of the pellet has proper viscosity, good pelletizing performance can be kept, the proportioning of bentonite is reduced, the influence of overlarge viscosity on the production and quality of the flux pellet is avoided, simultaneously, the mixed flux releases carbon dioxide through thermal decomposition reaction to adjust the micro porosity of the pellet, the flux pellet has proper micro porosity, the stress concentration during the reduction expansion period of the flux pellet can be relieved, the effect of reducing the reduction expansion is realized in the mechanism, the existing pellet has the characteristics of proper viscosity, proper micro porosity and low bentonite dosage, the problem of the over-adhesion of the mixed material and the problem of high-grade silicon low-grade powder caused by the overlarge dosage of the bentonite when the limestone is singly matched with the slaked lime are effectively avoided, and the requirement of high quality ratio of the high-grade silicon powder of the pellet on the high-grade pellet is met.
In the application, the flux can promote the melting of the concentrate powder in the preparation process of the pellet, and more importantly, the flux is used for controlling the alkalinity of the pellet to be 1.1 +/-0.1, controlling the viscosity of the pelletizing material to be proper and controlling the micro porosity of the pellet to be proper.
In this application, the binder is used to bind the fine pellet powder and the flux into a pellet.
In the present application, the concentrate powder may be commercially available products such as iron concentrate powder, which are commonly used in the art.
As an implementation mode of the embodiment of the application, the mass part of the concentrate powder is 95.1-97.4 parts; the mass portion of the binder is 0.5-1.6.
In the application, the reasons for controlling 1.5-1.9 parts of slaked lime, 0.6-1.0 part of limestone, 95.1-97.4 parts of pellet fine powder and 0.5-1.6 parts of binder are as follows: the optimal proportion of the fusing agent is determined by an orthogonal experiment method, the viscosity of the mixture is optimal, the proportion of the bentonite is reduced, the appropriate micro porosity of the pellet is provided, and the low-silicon fusing agent pellet ore with excellent performance can be produced and prepared.
As an embodiment of the examples of the present application, the proportion of slaked lime having a particle size of less than 200 mesh in the slaked lime is > 95% by weight.
As an implementation of the examples herein, limestone having a particle size of less than 325 mesh is present in the limestone in a proportion of > 90% by weight.
In the application, the slaked lime with the granularity of less than 200 meshes accounts for more than 95 percent of the whole slaked lime; the reason why the limestone with the particle size smaller than 325 meshes accounts for more than 90 percent of the whole limestone is that: the specific surface areas of the two fluxes are increased, the pelletizing performance is enhanced, the adverse effect of excessively small ratio is adverse to the pelletizing process, the proportion of bentonite is increased, the material pelletizing performance is poor, and the compressive strength of the finished pellets is reduced.
As an implementation of the embodiments of the present application, the binder includes at least one of bentonite and composite bentonite; the concentrate powder includes iron concentrate powder.
In the present application, binders include, but are not limited to: at least one of bentonite and composite bentonite; the binder has the function of improving the pelletizing performance of the pellet mixture, so as to improve the pellet green-ball index and the metallurgical performance, the principle of controlling the dosage of the binder is to reduce gangue entrainment as much as possible on the premise of ensuring the pellet green-ball strength, and the adverse effect of overlarge weight part is that the gangue content SiO in the pellet ore is too high 2 The adverse effects of too small a size are difficult pelletizing, low green strength of the pellets and poor pellet quality.
In the present application, the composite bentonite is specifically bentonite added with an organic binder.
As an implementation manner of the embodiment of the present application, the basicity of the pellet is 1.0 to 1.2; the micro porosity of the pellet is 26-29%.
In a second aspect, the present embodiments provide a method for preparing pellets according to the first aspect, as shown in fig. 1, the method includes:
stirring and mixing the raw materials of each component to obtain a premix;
pelletizing the premix, and then 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 pellet ore, no additional specific equipment is needed, the preparation method is simple to operate, batch production can be realized, and the quality requirement of the pellet ore with a high charging ratio is met.
As an implementation manner of the embodiment of the present application, pelletizing the premix, and then sieving to obtain a green pellet specifically includes:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and then screening to obtain green pellets with the granularity of 8-16 mm.
In the application, the mixture is controlled to be added with 7.8 to 8.8 parts by weight of water for pelletizing to obtain green pellets, and the reason why the granularity of the green pellets is 8mm to 16mm is as follows: the limestone powder has strong water absorption, poor balling property and good balling property, and the weight of added water needs to be properly increased for meeting the balling requirement when the two fluxes are mixed; in order to meet the air permeability requirement of roasting, the green pellets need to be screened, qualified green pellets are screened out to be subjected to the next step, unqualified green pellets are returned, and pelletizing is carried out again; of course, other suitable particle sizes may be selected.
As an implementation manner of the embodiment of the present application, the process parameters of preheating include: the temperature is 650-1100 ℃, and the time 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 full decomposition reaction of compounds such as crystal water decomposition and evaporation is ensured, the proper high preheating temperature and full preheating practice are required to be ensured when limestone powder is added, the full pyrolysis reaction of the limestone powder is ensured, and the micro porosity of the flux pellets is adjusted.
As an implementation manner of the embodiment of the present application, the baking process parameters include: the temperature is 1200-1280 ℃, and the time 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 flux balls is increased, the temperature in a roasting system is reduced due to decomposition and heat absorption of the limestone powder, the strength control of the pellets is not facilitated, the roasting temperature is properly increased, the roasting time is prolonged, and the iron oxide is ensured to be fully oxidized and form firm Fe 2 O 3 Recrystallization bonds, strengthen the generation of secondary hematite, thereby strengthening Fe 2 O 3 And (5) recrystallizing and consolidating.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental methods without specifying specific conditions in the following examples were generally determined according to national standards. If there is no corresponding national standard, it is carried out according to the usual international standards, to the conventional conditions or to the conditions recommended by the manufacturer.
Test examples
According to the embodiment of the pellet described in the first aspect, the present example provides an orthogonal experiment method for determining the optimal ratio of flux, as shown in fig. 3, the method includes the following steps: according to the flux pellet alkalinity requirement (R = 1.1), performing ingredient measurement according to the existing raw material conditions (Peru powder + Hainan powder), completing an ingredient basic test table on the premise of meeting ingredient component requirements, and performing various proportioning pelletizing tests according to a small pelletizing disk in a laboratory, wherein 4 ingredient schemes are preferably selected (the experiment ratio is 1-4, wherein the experiment ratio is 1: peru powder: hainan powder =91.5: peru powder: hainan powder = 91.5; 1.05 percent of externally-prepared bentonite and 2.35 percent of slaked lime; limestone means that only limestone is used as a flux: peru powder: hainan powder = 91.5; 1.05 percent of externally-prepared bentonite and 3.35 percent of limestone. The two proportioning schemes are original proportioning modes and are used as test comparison. The above mixture ratio is tested in a repeated laboratory (the technological parameters are fixed according to the original production parameters of the slaked lime), and the optimal test mixture ratio 3 is selected (Peru powder: hainan powder = 91.5; external bentonite 1.05%, slaked lime 1.75%, limestone 0.85%).
According to the content of the embodiment of the pellet preparation method of the second aspect, the thermal technology is optimized on the basis of the optimal flux ratio of the orthogonal experiment, as shown in fig. 4, according to the heat consumption characteristic of limestone powder thermal decomposition (825-896 ℃), 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 that the strength of the matched limestone powder is slightly low is solved. Examples production of flux pellets the expected effect was achieved: the components are unchanged, the reduction expansion is reduced, and the cost is optimized.
Example 1
The present embodiment provides a pellet, and the preparation process thereof is shown in fig. 2, and specifically includes:
the first step is as follows: preparing materials: iron ore concentrate powder, limestone, slaked lime and a binder are mixed according to the quality requirement of the pellets; 0.85 part of limestone, 1.75 parts of slaked lime, 91.5 parts of Peru iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.05 parts of calcium bentonite;
the second step is that: uniformly mixing: mixing the pellet fine powder, flux and binder;
the third step: pelletizing: adding proper water into a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: and (3) putting the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine by using a shuttle type distributing machine for drying, preheating and roasting. The drying temperature is 390 ℃, and the drying time is 7.2min; preheating temperature is 650-1100 deg.C, and preheating time is 7min; the roasting temperature is 1250 ℃, and the roasting time is 9.8min; soaking temperature is 1150 deg.C, and soaking time is 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 1.10; the micro-porosity of the pellets is 27.15%.
Example 2
The embodiment of the present application differs from embodiment 1 in that: the limestone proportion is reduced, and the slaked lime proportion is improved. The method specifically comprises the following steps:
the first step is as follows: preparing materials: iron ore concentrate powder, limestone, slaked lime and a binder are mixed according to the quality requirement of the pellets; 0.6 part of limestone, 2 parts of slaked lime, 91.5 parts of Peru iron ore concentrate powder, 4.8 parts of Hainan iron ore concentrate powder and 1.05 parts of calcium bentonite;
the second step is that: uniformly mixing: fully and uniformly mixing various pellet fine powders, a flux and a binder;
the third step: pelletizing: adding proper water into a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: placing qualified green balls with the diameter of 8mm-16mm into a belt type roasting machine by using a shuttle type distributing machine for drying, preheating and roasting; the drying temperature is 360 ℃, and the drying time is 7min; preheating temperature is 650-1050 ℃, and preheating time is 6.7min; the roasting temperature is 1240 ℃, and the roasting time is 9.5min; soaking temperature is 1150 deg.C, and soaking time is 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 1.11; the micro-porosity of the pellets was 26.95%.
Comparative example 1
Comparative example 1 of the present application differs from example 1 in that: stopping preparing limestone and only adding slaked lime as flux. The method specifically comprises the following steps:
the first step is as follows: preparing materials: iron ore concentrate powder, slaked lime and a binder are mixed according to the quality requirement of the pellets; 2.6 parts of slaked lime, 91.5 parts of Peru iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 0.97 part of calcium bentonite;
the second step is that: uniformly mixing: fully and uniformly mixing various pellet fine powders, a flux and a binder;
the third step: pelletizing: adding proper water to a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: using a shuttle distributing machine to place the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine for drying, preheating and roasting; the drying temperature is 330 ℃, and the drying time is 6.7min; preheating at 550-1050 deg.C for 6.5min; the roasting temperature is 1230 ℃, and the roasting time is 9.5min; soaking temperature is 1150 deg.C, and soaking time is 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 1.10; the micro-porosity of the pellets was 23.9%.
Comparative example 2
Comparative example 2 of the present application differs from example 1 in that: a small amount of limestone is added, the proportion of the limestone is 0.3 percent, and slaked lime is mainly used as a fusing agent. The method specifically comprises the following steps:
the first step is as follows: preparing materials: iron ore concentrate powder, limestone, slaked lime and a binder are mixed according to the quality requirement of the pellets; 0.3 part of limestone, 2.3 parts of slaked lime, 91.5 parts of Peru iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.02 parts of calcium bentonite;
the second step is that: uniformly mixing: fully and uniformly mixing various pellet fine powders, a flux and a binder;
the third step: pelletizing: adding proper water to a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: using a shuttle distributing machine to place the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine for drying, preheating and roasting; the drying temperature is 390 ℃, and the drying time is 7.2min; preheating temperature is 650-1100 deg.C, and preheating time is 7min; the roasting temperature is 1250 ℃, and the roasting time is 9.8min; soaking at 1150 deg.C for 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 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 the slaked lime is 0.6 percent, and limestone is mainly used as a fusing agent; the method specifically comprises the following steps:
the first step is as follows: preparing materials: iron ore concentrate powder, limestone, slaked lime and a binder are mixed according to the quality requirement of the pellets; 2.15 parts of limestone, 0.6 part of slaked lime, 91.5 parts of Peru iron ore concentrate powder, 4.8 parts of Hainan iron ore concentrate powder and 1.3 parts of calcium bentonite;
the second step is that: uniformly mixing: fully and uniformly mixing various pellet fine powders, a flux and a binder;
the third step: pelletizing: adding proper water into a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: placing qualified green balls with the diameter of 8mm-16mm into a belt type roasting machine by using a shuttle type distributing machine for drying, preheating and roasting; the drying temperature is 450 ℃, and the drying time is 7.5min; preheating temperature is 650-1150 ℃, and preheating time is 7.5min; the roasting temperature is 1280 ℃, and the roasting time is 10.5min; soaking temperature is 1150 deg.C, and soaking time is 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 1.12; the micro-porosity of the pellets was 32%.
Comparative example 4
Comparative example 4 of the present application differs from example 1 in that: and (4) stopping preparing slaked lime, and taking limestone as a fusing agent. The method specifically comprises the following steps:
the first step is as follows: preparing materials: iron ore concentrate powder, limestone and a binder are mixed according to the quality requirement of the pellets; 4.3 parts of limestone, 91.5 parts of Peru iron concentrate powder, 4.8 parts of Hainan iron concentrate powder and 1.55 parts of calcium bentonite;
the second step: uniformly mixing: fully and uniformly mixing various pellet fine powders, a flux and a binder;
the third step: pelletizing: adding proper water into a disc pelletizer to pelletize, and controlling the water content to be 8.3 +/-0.5%;
the fourth step: green ball screening: screening qualified green balls with the granularity of 8-16 mm by using a double-layer roller screen;
the fifth step: and (3) putting the qualified green pellets with the diameter of 8mm-16mm into a belt type roasting machine by using a shuttle type distributing machine for drying, preheating and roasting. The drying temperature is 450 ℃, and the drying time is 7.8min; preheating temperature is 650-1150 ℃, and preheating time is 7.5min; the roasting temperature is 1280 ℃, and the roasting time is 10.8min; soaking temperature is 1150 deg.C, and soaking time is 3min;
and a sixth step: balling and cooling: cooling to below 120 ℃ in the cooling section of the belt type roasting machine.
The alkalinity of the pellet obtained in the example is 1.12; the micro-porosity of the pellet 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 proportioning table of examples and comparative examples
| Serial number | Peru powder | Hainan powder | Slaked lime | Limestone | 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 composition and Property parameters of finished pellets from examples and comparative examples
| Serial number | TFe％ | SiO 2 ％ | CaO％ | Alkalinity% | Compressive strength | Reduction and 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 pellet prepared by the mixture ratio and the method provided by the embodiment of the invention is matched with the mixed flux with proper proportion, the compressive strength of the pellet is stable, and the compressive strength can be kept above 3200N/p; the pellet silicon has low quality and high quality, the silicon content is about 2.2 percent, and the quality is more than 65 percent; the reduction expansion is as low as 15.6%, the comparison of the comparative example and the data of the example can obtain that only lime hydrate is added as the fusing agent, or the limestone amount is added, the micro porosity of the fusing agent pellets is not good, and the reduction expansion is higher than 17%; and the slaked lime is added in a large amount, the viscosity of the mixture is high, the production stability is influenced by frequent bonding of a production system, the green ball quality is poor, and the deformation of the pellets is serious. Only limestone is added as a fusing agent, or the amount of limestone removal is too small, the balling property of the mixture is poor, the proportion of bentonite is increased, the silicon pellets reaches about 3 percent, and the taste is reduced to below 65 percent; and the limestone proportion is large, the pellet pores are too much, the pellet strength control is not facilitated, and the compression resistance of the pellet is reduced to below 3000N/p.
In summary, the embodiment of the application provides a pellet ore and a preparation method thereof, by optimizing the flux addition method of the flux pellet, and taking slaked lime as a main component and limestone as an auxiliary component as the flux, the best viscosity of the flux is flexibly adjusted, the proportion of bentonite is reduced, the influence of overlarge flux viscosity on material transportation and pelletizing is avoided, and the micro porosity of the pellet is improved. Can produce a low-silicon low-expansion high-quality flux pellet ore, effectively meets the requirement of a high-sphericity ratio furnace on the quality of the pellet ore, is beneficial to the green development of the steel industry, and has remarkable social benefit and economic benefit.
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 such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be 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. Also, 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 only one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. 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 invention. Thus, the present invention 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 (10)
1. A pellet, characterized in that the pellet comprises the following components:
fusing agent; fine mineral powder; and a binder;
the flux comprises the following components in parts by mass: 1.5 to 1.9 portions of slaked lime and 0.6 to 1.0 portion of limestone.
2. The pellet as claimed in claim 1, wherein the mass fraction of the concentrate powder is 95.1-97.4; the mass portion of the binder is 0.5-1.6.
3. Pellet as claimed in claim 1, characterized in that the proportion of slaked lime having a particle size of less than 200 mesh in the slaked lime is > 95% in weight fraction.
4. The pellet as claimed in claim 1, wherein the limestone having a particle size of less than 325 mesh is > 90% by weight.
5. The pellet as claimed in claim 1, wherein the binder comprises at least one of bentonite and composite bentonite; the concentrate powder includes iron concentrate powder.
6. The pellet as claimed in any one of claims 1 to 5, wherein the basicity of the pellet is 1.0 to 1.2; the micro porosity of the pellet is 26% -29%.
7. A method for preparing pellets as claimed in any one of claims 1 to 6, which comprises:
stirring and mixing the raw materials of each component to obtain a premix;
pelletizing the premix, and then screening to obtain green pellets;
and drying, preheating, roasting and cooling the green pellets to obtain pellets.
8. The method for preparing pellet ore according to claim 7, wherein the pelletizing the premix and then screening to obtain green pellets specifically comprises:
adding 7.8-8.8 parts by weight of water into the premix for pelletizing, and then screening to obtain green pellets with the granularity of 8-16 mm.
9. The method for manufacturing pellets as claimed in claim 7, wherein the preheated process parameters include: the temperature is 650-1100 ℃, and the time duration is 6-7.5 min.
10. The method for preparing pellets as claimed in claim 7, wherein the roasting process parameters include: the temperature is 1200-1280 ℃, and the time duration is 8.3-10.6 min.
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| CN115747483A (en) * | 2022-12-26 | 2023-03-07 | 中天钢铁集团(南通)有限公司 | Production method of zero-bentonite pellets |
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| 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 |
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| 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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| CN115747483A (en) * | 2022-12-26 | 2023-03-07 | 中天钢铁集团(南通)有限公司 | Production method of zero-bentonite pellets |
| CN115747483B (en) * | 2022-12-26 | 2024-06-07 | 中天钢铁集团(南通)有限公司 | Production method of zero bentonite pellets |
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