CN112410547A - Preparation method of composite iron-carbon sintered ore and blast furnace smelting process - Google Patents
Preparation method of composite iron-carbon sintered ore and blast furnace smelting process Download PDFInfo
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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
- C22B1/16—Sintering; Agglomerating
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- C21—METALLURGY OF IRON
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Abstract
A preparation method of composite iron-carbon sinter comprises the following steps: 1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture; 2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet; 3) microwave sintering: and (3) distributing the sintered green pellets, and then sintering by using microwaves, wherein volatile matters and crystal water are decomposed and volatilized, and fixed carbon particles in the iron ore and coal are crushed and recrystallized to obtain the high-strength composite iron-carbon sintered ore, which has the effects of sintered ore, pellet and coke and is a high-quality blast furnace burden. According to the invention, microwave heating sintering is adopted, so that fixed carbon in coal is not reacted in the sintering process, iron ore and particles of the fixed carbon are crushed and recrystallized, and the high-strength high-quality composite iron-carbon sintered ore is prepared, the production efficiency of the blast furnace is improved, and the dependence of the blast furnace on coke is relieved.
Description
Technical Field
The invention relates to preparation and application of a composite sintered ore, in particular to a preparation method of a composite iron-carbon sintered ore and a blast furnace ironmaking process, and belongs to the technical field of ironmaking raw material production.
Background
Blast furnace ironmaking is an important link in steel production. The method is developed and improved by ancient shaft furnace ironmaking. Although many new iron-making methods are researched and developed in various countries in the world, because the blast furnace iron-making technology has good economic indexes, simple process, large production capacity, high labor productivity and low energy consumption, the iron produced by the method still accounts for more than 95 percent of the total iron production in the world.
At present, the blast furnace top charging system in blast furnace iron making is the most widely applied blast furnace bell-less top charging system. When a bell-less and tank-type top charging system (suitable for large blast furnaces) is used for charging, the charging materials generally need to pass through the process flows of belt feeding, top charging device feeding, rotary chute distribution and the like before being charged into the throat of the blast furnace, as shown in fig. 1. However, the charge is accompanied by segregation behaviour of the particles during the above operations, which directly or indirectly affect the distribution of the charge in the blast furnace. Wherein, segregation behavior of furnace charge particles in the belt feeding process can influence the particle distribution in the charging basket when charging the furnace top and the charging basket, so that the particle size distribution of the particles in the two charging baskets is more uneven; in the process of carrying out tank combination and charging on furnace burden, due to the special structure of the tank combination, the furnace burden enters the two tanks and has different material flow tracks and drop point positions, so that the furnace burden forms different particle size segregation structures in the two tanks, the distribution of particles in the furnace in the subsequent tank combination, tank cutting and material distribution processes is greatly influenced, finally, the distribution of gas flow in the furnace is fluctuated, and the production of a blast furnace is not facilitated.
The bell-less parallel tank type furnace top charging system of the blast furnace is used as a research background, in the charging and parallel tank charging process of a belt conveyor, the particle segregation of mineral materials in the processes of belt conveying, tank charging and the like is serious, the subsequent chute distribution segregation is serious, the coal gas in the furnace is unevenly distributed and the utilization rate is low, the smelting coke ratio is increased, the effective volume utilization coefficient of the blast furnace is reduced, and the full oxidation reduction effect of iron ore in the blast furnace, namely the recovery of Fe in the iron ore and the stable smooth running of the furnace condition are not facilitated. The particle size segregation on the feeding belt can lead the particles to be distributed more unevenly in the charging bucket, and in the process of loading the particles in the charging bucket, the particles are easy to form different particle size segregation structures in the two buckets, so that the distribution of furnace burden in the furnace is fluctuated when the material is distributed in the subsequent cutting bucket, further, the coal gas in the furnace is fluctuated, and the stable and smooth operation of the blast furnace is influenced. In addition, the blast furnace production process is over dependent on coke, which not only causes the shortage of coke resources, but also seriously pollutes the environment in the coke making process, and is not beneficial to the sustainable development of the blast furnace production.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of a high-strength composite iron-carbon sintered ore and a blast furnace smelting process method. The invention introduces a microwave heating process, adopts microwave to directly heat the sintering material, and utilizes the characteristics of rapid heating, volume heating, selective heating (thermal effect) and lattice reforming (non-thermal effect) of iron oxide under the action of microwave to ensure that fixed carbon in coal is not reacted in the sintering process, and iron ore and fixed carbon particles of coal are crushed and recrystallized to prepare the high-strength composite iron-carbon sintering ore.
The prepared composite iron-carbon sintered ore is directly used as a blast furnace raw material for smelting, additional fuel is not needed, a coking process is omitted, and the process flow is greatly shortened; meanwhile, the composite iron-carbon sintered ore is directly used as a blast furnace raw material for smelting, so that the material distribution is more uniform, and the phenomenon that the sintering mixture and the fuel are distributed in a layered manner and are easy to segregate in the prior art is avoided.
According to a first embodiment of the present invention, there is provided a method for manufacturing a composite iron-carbon sintered ore.
A preparation method of composite iron-carbon sinter comprises the following steps:
1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture;
2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet;
3) microwave sintering: and (3) after the sintered green pellets are distributed and sintered, adopting microwave sintering, wherein volatile matters and crystal water in the sintered green pellets are decomposed and volatilized, and the iron ore and fixed carbon particles in coal are crushed and recrystallized to obtain the high-strength composite iron-carbon sintered ore.
Preferably, oxygen-free or low-oxygen sintering is used in step 3).
Preferably, the oxygen concentration in the sintering system during the microwave sintering in step 3) is less than 16%, preferably less than 13%, and more preferably less than 10%.
In the present invention, the temperature of the microwave sintering in step 3) is controlled to be not higher than 1300 ℃, preferably not higher than 1250 ℃, and more preferably not higher than 1200 ℃.
Preferably, during the microwave sintering process in the step 3), nitrogen or inert gas is introduced into the sintering system. The introduced nitrogen or inert gas mainly plays a role in air induction, so that the generated gas is discharged in time, and deep reduction of iron and rapid combustion of coal are also prevented.
Preferably, the step 3) further comprises a step of cooling the sintered ore, specifically: and introducing nitrogen or inert gas to cool the composite iron-carbon sintered ore after microwave sintering.
In the invention, in the sintering mixture obtained in the step 1), the weight ratio of the iron ore, the coal and the flux is 50-80:20-50:1-10, preferably 60-70:30-40: 3-8.
In the invention, the mixing in the step 1) is performed by adopting an intensive mixer for intensive mixing.
In the invention, the granulation in the step 2) adopts a roller granulation or disc granulation mode.
In the invention, the composite iron-carbon sintered ore obtained in the step 3) also comprises a silicate binder phase.
In the invention, the microwave sintering in the step 3) is specifically as follows: and adopting one or more microwave sources, and heating and roasting the sintered green pellets after distribution by the microwave sources.
According to a second embodiment of the present invention, a blast furnace process is provided.
A blast furnace smelting process method comprises the following steps:
1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture;
2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet;
3) microwave sintering: after the sintered green pellets are distributed and sintered in the system, microwave sintering is adopted, wherein volatile matters and crystal water in the sintered green pellets are decomposed and volatilized, and iron ore and fixed carbon particles in coal are crushed and recrystallized to obtain high-strength composite iron-carbon sintered ore;
4) conveying the composite iron-carbon sintered ore obtained in the step 3) into a blast furnace for smelting to obtain molten iron.
Preferably, oxygen-free or low-oxygen sintering is used in step 3).
Preferably, the oxygen concentration in the sintering system during the microwave sintering in step 3) is less than 16%, preferably less than 13%, and more preferably less than 10%.
In the present invention, the temperature of the microwave sintering in step 3) is controlled to be not higher than 1300 ℃, preferably not higher than 1250 ℃, and more preferably not higher than 1200 ℃.
Preferably, during the microwave sintering process in the step 3), nitrogen or inert gas is introduced into the sintering system. The introduced nitrogen or inert gas mainly plays a role in air induction, so that the generated gas is discharged in time, and deep reduction of iron and rapid combustion of coal are also prevented.
Preferably, the step 3) further comprises a step of cooling the sintered ore, specifically: and introducing nitrogen or inert gas to cool the composite iron-carbon sintered ore after microwave sintering.
In the invention, in the sintering mixture obtained in the step 1), the weight ratio of the iron ore, the coal and the flux is 50-80:20-50:1-10, preferably 60-70:30-40: 3-8.
In the invention, the mixing in the step 1) is performed by adopting an intensive mixer for intensive mixing.
In the invention, the granulation in the step 2) adopts a roller granulation or disc granulation mode.
In the invention, the composite iron-carbon sintered ore obtained in the step 3) also comprises a silicate binder phase.
In the invention, the microwave sintering in the step 3) is specifically as follows: and adopting one or more microwave sources, and heating and roasting the sintered green pellets after distribution by the microwave sources.
The invention provides a preparation method of a composite iron-carbon sintered ore. After the materials are mixed, the mixture is strongly mixed and then is granulated by a roller or pelletized by a disc to prepare the sintered green pellets. And then distributing the sintered green pellets, and roasting and consolidating the green pellets by adopting microwave sintering after distributing to obtain the high-strength composite iron-carbon sintered ore. In the present invention, the microwave sintering is performed in a closed environment without oxygen or with weak oxygen. Preferably, nitrogen or inert gas is introduced at the same time of microwave sintering, so that the microwave sintering is carried out under the protective atmosphere of nitrogen or inert gas. In the present invention, the temperature of the microwave sintering is 1300 ℃ or less, preferably 1250 ℃ or less, and more preferably 1200 ℃ or less. The roasting consolidation mechanism is that after the green pellets are sintered to absorb microwaves, the iron ore and fixed carbon particles in coal are crushed and recrystallized to consolidate the iron ore and the fixed carbon particles together, and a part of silicate binder phase exists at the same time, so that the strength of the sintered ore is ensured. Preferably, the step of cooling the sintered ore after the microwave sintering is also included, namely, nitrogen or inert gas is introduced to cool the sintered ore. In the invention, nitrogen or inert gas is introduced in the microwave sintering process, so that on one hand, an oxygen-free or weak-oxygen environment can be realized, and simultaneously, the nitrogen or inert gas also plays a role in protection. Nitrogen or inert gas is also introduced in the cooling process after microwave sintering, so that the sintered ore can be cooled and the protection effect is also achieved.
In the prior art, fuel (such as coke and the like) and iron ore are sintered and then added with new coke to enter a blast furnace. In the conventional sintering process, fuel is subjected to combustion reaction, so that when the blast furnace is used for iron making and distributing, additional fuel needs to be added into the blast furnace. In addition, the round pellets and irregular sintered ores are seriously subjected to particle segregation in the processes of belt conveying, canning and the like, and are easily segregated to the edge of the blast furnace when entering the mixed material distribution of the blast furnace, so that the operation fluctuation of the blast furnace is caused, and the quality of molten iron is reduced. Segregation is easy to occur when iron-containing furnace burden and coke are distributed in a layered manner in the blast furnace.
Aiming at the problem that iron-containing furnace burden and coke are easy to segregate during distribution in a blast furnace in the prior art, a microwave heating process is introduced, namely, microwave sintering is adopted in the sintering process of coal and iron ore, the oxygen consumption required by the microwave sintering is small, at the moment, fixed carbon in the coal is not reacted, the iron ore and fixed carbon particles in the coal are crushed and recrystallized, and the iron ore and the fixed carbon particles are consolidated together to form iron coke, namely, composite iron-carbon sintered ore. Part of silicate binder phase exists in the composite iron-carbon sintered ore to ensure the strength of the sintered ore. Aiming at the defects of the prior art, the invention also provides the application of the composite iron-carbon sinter prepared by the preparation method in blast furnace iron making, and the application method comprises the following steps: and uniformly distributing the composite iron-carbon sintered ore in a blast furnace for smelting. Compared with the traditional sintering ore sintering and blast furnace iron-making processes, the composite iron-carbon sintering ore provided by the invention is used for blast furnace iron-making, does not need to add additional fuel, can be directly used as a blast furnace raw material for smelting, and saves a coking process. And when the blast furnace burden is distributed, the composite iron-carbon sinter provided by the invention is more uniform in distribution, and the phenomenon that the sinter of the conventional iron-containing burden and coke are distributed in a layered manner and are easy to segregate is avoided. Meanwhile, the iron and carbon in the composite iron and carbon sintered ore are in close contact, the gasification reaction in the blast furnace is rapid, the smelting efficiency is improved, the bottom reaction of the blast furnace is optimized, the reaction flow is shortened, the reaction efficiency is improved, the quality of the obtained molten iron is good, the carbon content is low, and the energy consumption of subsequent decarburization is reduced.
In the prior art, the raw materials for blast furnace smelting are sintered ore pellets after a sintering process. The sintering raw materials comprise iron ore, fuel, flux and the like, and are mixed to obtain the sintering raw materials; and then conveying the sintering raw materials to a sintering system for sintering and roasting, wherein fuel is combusted in the sintering system to provide heat for roasting and consolidating the iron ore. The fuel in the sintering raw material provides heat in the sintering process of the sintered ore pellets after the sintering process, and the use is finished. Then the sintered ore pellets obtained through the sintering process are conveyed to a blast furnace, and fuel (generally coke) is added again and mixed to be smelted in the blast furnace. In the prior art, the sinter pellets and the coke are added simultaneously during charging of the blast furnace. However, as the grain diameter difference between the sintered ore pellets and the coke is increased, the segregation condition inevitably occurs when the sintered ore pellets and the coke are added into the blast furnace, so that the coke and the sintered ore pellets are layered in the blast furnace. In the prior art, a layer of sinter ore pellets, a layer of coke, a layer of sinter ore pellets and a layer of coke … … exist in a blast furnace; namely, the materials in the blast furnace are in an interval layered state of 'sinter pellets-coke-sinter pellets-coke'. The phenomenon results in poor heat transfer effect after blast furnace smelting, uneven heating of the sinter pellets in the blast furnace, no contribution to the occurrence of direct reduction reaction at the upper part of the blast furnace, long smelting time and low efficiency; and the obtained molten iron has low quality and high carbon content, and the obtained molten iron must be subjected to decarburization treatment subsequently.
The process of the invention skillfully combines the process requirements of blast furnace smelting by introducing microwave sintering, adds fuel coal powder into the sintering mixture, and then adopts microwave sintering to obtain the high-strength composite iron-carbon sinter. Because the microwave sintering is adopted, fuel is not consumed in the sintering process, and heat is provided by microwaves to roast and consolidate the iron ore. Researches and experiments show that coal can be changed in the process by adopting microwave sintering, volatile components in the coal react, iron ore and fixed carbon in the coal are crushed and recrystallized in the process, and the iron ore and the fixed carbon in the coal are tightly combined together to form the composite iron-carbon sintered ore uniformly containing the iron ore and the fixed carbon. The composite iron-carbon sintered ore obtained through the sintering process is used as a blast furnace raw material, and because the composite iron-carbon sintered ore contains fixed carbon, the composite iron-carbon sintered ore only needs to be added in the smelting process of the blast furnace, and new fuel does not need to be added additionally to directly smelt. Because the coal in the composite iron-carbon sinter is added into the sintering mixture, the iron ore and the coal are subjected to the working procedures of mixing (especially strong mixing), granulating, pelletizing and the like, the coal and the iron-containing raw material are uniformly mixed, and the condition of layering in a blast furnace is avoided. In the prior art, the raw materials of the blast furnace are sinter ore pellets and coke, and just because of the existence of the sinter ore pellets, the blast furnace raw materials cannot be uniformly mixed by adopting equipment such as a mixer and the like when the sinter ore pellets are added into the blast furnace, otherwise, the sinter ore pellets are damaged. According to the invention, iron ore and coal are uniformly mixed in a sintering mixture before a sintering process, then the mixture is subjected to granulation and pelletizing processes, and then microwave sintering is carried out, because fixed carbon in the coal is not consumed by the microwave sintering, only volatile components in the coal are reacted, so that the composite iron-carbon sintered ore with uniformly mixed iron-containing raw materials and fixed carbon in the coal is obtained, and meanwhile, the volatile components in the coal are removed. And then the composite iron-carbon sintered ore containing fixed carbon is used as a raw material for blast furnace smelting and is conveyed to a blast furnace, and new fuel does not need to be added again, so that the problem of segregation of the blast furnace raw material is fundamentally avoided. In addition, the composite iron-carbon sintered ore processed by the process is used as a blast furnace raw material, the iron-containing component and the coal are uniformly mixed, the coal provides heat and a reducing agent in the blast furnace, the sintered ore pellets are uniformly heated in the blast furnace, the occurrence of direct reduction reaction is accelerated, the smelting time is shortened, and the efficiency is high; the obtained molten iron has high quality and low carbon content, and the obtained molten iron does not need to be subjected to decarburization treatment subsequently.
In addition, in the technical scheme of the application, coal is subjected to a sintering process, wherein volatile matters and crystal water in the coal are decomposed and volatilized, and iron ore and fixed carbon particles in the coal are crushed and recrystallized to obtain the high-strength composite iron-carbon sintered ore. In the prior art, the fuel added to the blast furnace requires a separate coking treatment to obtain coke; then the coke and the iron-containing raw material which is subjected to the sintering process are added into a blast furnace. The technical scheme of the invention utilizes the sintering process, realizes the coking process of coal, shortens the process flow and saves the energy consumption of coking.
The invention preferably adopts an anaerobic or low-oxygen environment for sintering, because the microwave provides heat, the coal is prevented from burning in the sintering process as much as possible, and the anaerobic or low-oxygen environment is adopted for sintering to ensure the fixed carbon component in the coal in the composite iron-carbon sintered ore.
Because the microwave sintering is adopted, the fixed carbon in the coal does not need to be combusted, the temperature of the sintering process is controlled to be lower than 1300 ℃, the microwave provides heat and radiation energy, and the consolidation of the iron ore and the fixed carbon particles in the coal is facilitated.
In the present application, "volatiles" and "volatiles" are used interchangeably. The fuel in the invention is mainly coal, and other fuels can also be adopted.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention introduces a microwave heating process, adopts microwave to directly heat the sintering material, and utilizes the characteristics of rapid heating, volume heating, selective heating (thermal effect) and lattice reforming (non-thermal effect) of iron oxide under the action of microwave to ensure that fixed carbon in coal is not reacted in the sintering process, iron ore and fixed carbon particles in coal are crushed and recrystallized to prepare the high-strength composite iron-carbon sintering ore;
2. the prepared composite iron-carbon sintered ore is directly used as a blast furnace raw material for smelting, additional fuel is not needed, a coking process is omitted, and the process flow is greatly shortened;
3. the prepared composite iron-carbon sintered ore is directly used as a blast furnace raw material for smelting, so that the material distribution is more uniform, the phenomenon that a sintering mixture and coke layered material distribution are easy to segregate in the prior art is avoided, and meanwhile, the iron carbon in the composite iron-carbon sintered ore is in close contact with each other, the gasification reaction in the blast furnace is rapid, the smelting efficiency is improved, the bottom reaction of the blast furnace is optimized, the quality of the obtained molten iron is good, the carbon content is low, and the energy consumption of subsequent decarburization is reduced;
4. the microwave sintering is adopted, the microwaves directly act on the material body, the conduction heat loss is reduced, no gas is generated during microwave heating, and the exhaust emission is reduced, so that the purposes of energy conservation and emission reduction are achieved.
Drawings
FIG. 1 is a flow diagram of a prior art process for preparing sintered ore;
FIG. 2 is a flow chart of a process for preparing a composite iron-carbon sintered ore according to the present invention;
FIG. 3 is a process flow diagram of blast furnace smelting in the prior art;
FIG. 4 is a process flow chart of the composite iron-carbon sintered ore prepared by the invention for blast furnace smelting.
Detailed Description
For a better understanding of the present invention, reference will now be made in detail to the present invention by way of specific embodiments thereof. It should be understood by those skilled in the art that the following examples are illustrative only and not limiting to the present invention, and that changes and modifications to the above-described examples may be made within the spirit and scope of the present invention as defined by the appended claims.
Example 1
As shown in fig. 2, a method for preparing a composite iron-carbon sintered ore includes the following steps:
1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture;
2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet;
3) microwave sintering: and distributing the sintered green pellets, and then sintering by using microwaves, wherein volatile matters and crystal water in the sintered green pellets are decomposed and volatilized, and the iron ore and fixed carbon particles in coal are crushed and recrystallized to obtain the high-strength composite iron-carbon sintered ore.
Wherein, the composite iron-carbon sinter obtained in the step 3) also comprises a silicate binder phase. The microwave sintering in the step 3) is specifically as follows: and adopting a plurality of microwave sources, and heating and roasting the sintered green pellets after distribution by the microwave sources.
Example 2
Example 1 is repeated except that step 3) further comprises a step of cooling the sinter, specifically: and introducing nitrogen to cool the composite iron-carbon sintered ore after microwave sintering.
Example 3
Example 2 is repeated except that the microwave sintering described in step 3) is performed in an oxygen-free or low-oxygen closed environment, specifically: and introducing nitrogen, and performing microwave sintering in a nitrogen protection environment. Wherein the oxygen concentration in the sintering system is less than 10%.
Example 4
Example 3 was repeated except that in step 3), the maximum temperature of the microwave sintering was 1200 ℃.
Example 5
Example 4 is repeated, except that in step 1), the sintering ingredients comprise the following raw materials in percentage by mass: 60 parts of iron ore, 35 parts of coal and 5 parts of flux.
Example 6
Example 5 was repeated except that the mixing described in step 1) was performed by intensive mixing.
Example 7
Example 6 was repeated, except that the granulation described in step 2) was carried out using a roller granulation.
Application example 1
As shown in fig. 4, the composite iron-carbon sintered ore prepared in example 7 is used for blast furnace ironmaking, and the application method comprises the following steps: and uniformly distributing the prepared composite iron-carbon sinter ore in a blast furnace for smelting.
TABLE 1 comparison of conventional sinter to composite sinter according to the invention in blast furnace smelting
The invention introduces a microwave heating process, adopts microwave sintering to ensure that the fixed carbon in the coal is not reacted in the sintering process, and the iron ore and the fixed carbon particles in the coal are crushed and recrystallized to prepare the high-strength composite iron-carbon sintered ore. As can be seen from table 1, in the present embodiment, the prepared composite iron-carbon sintered ore is directly used as a blast furnace raw material for smelting, no additional fuel is required to be added, a coking process is omitted, and the process flow is greatly shortened; the composite iron-carbon sintered ore is directly used as a blast furnace raw material, so that the material distribution is more uniform, and the phenomenon that the sintering mixture and fuel are distributed in a layered manner and are easy to segregate in the prior art is avoided; meanwhile, the iron and carbon in the composite iron and carbon sintered ore are in close contact, the gasification reaction in the blast furnace is rapid, the smelting efficiency is improved, the bottom reaction of the blast furnace is optimized, the obtained molten iron has good quality and low carbon content, and the energy consumption of subsequent decarburization is reduced.
Through engineering tests, compared with the conventional process (conventional sintering, fuel is added into sintering raw materials, and coke is added into blast furnace raw materials) by adopting the blast furnace smelting process, the test results are as follows:
TABLE 1 blast furnace smelting results comparison
Claims (10)
1. A preparation method of composite iron-carbon sinter comprises the following steps:
1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture;
2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet;
3) microwave sintering: and (3) after the sintered green pellets are distributed and sintered, adopting microwave sintering, wherein volatile matters and crystal water in the sintered green pellets are decomposed and volatilized, and the iron ore and fixed carbon particles in coal are crushed and recrystallized to obtain the high-strength composite iron-carbon sintered ore.
2. A blast furnace smelting process method comprises the following steps:
1) uniformly mixing the ingredients: mixing iron ore and coal, adding a fusing agent into the mixture, and mixing the mixed materials to obtain a sintering mixture;
2) and (3) granulating: granulating and pelletizing the sintering mixture to obtain a sintered green pellet;
3) microwave sintering: after the sintered green pellets are distributed and sintered in the system, microwave sintering is adopted, wherein volatile matters and crystal water in the sintered green pellets are decomposed and volatilized, and iron ore and fixed carbon particles in coal are crushed and recrystallized to obtain high-strength composite iron-carbon sintered ore;
4) conveying the composite iron-carbon sintered ore obtained in the step 3) into a blast furnace for smelting to obtain molten iron.
3. The method according to claim 1 or 2, characterized in that: in the step 3), anaerobic or low-oxygen sintering is adopted; preferably, the oxygen concentration in the sintering system during the microwave sintering in step 3) is less than 16%, preferably less than 13%, and more preferably less than 10%.
4. The method according to any one of claims 1-3, wherein: the temperature of the microwave sintering in the step 3) is controlled to be not higher than 1300 ℃, preferably not higher than 1250 ℃, and more preferably not higher than 1200 ℃.
5. The method according to any one of claims 1-4, wherein: and 3) in the microwave sintering process of the step 3), introducing nitrogen or inert gas into the sintering system.
6. The method according to any one of claims 1-5, wherein: the step 3) also comprises a step of cooling the sinter, which comprises the following specific steps: and introducing nitrogen or inert gas to cool the composite iron-carbon sintered ore after microwave sintering.
7. The method according to any one of claims 1-6, wherein: in the sintering mixture obtained in the step 1), the weight ratio of iron ore, coal and flux is 50-80:20-50:1-10, preferably 60-70:30-40: 3-8; and/or
In the step 1), the mixture is intensively mixed by adopting an intensive mixer.
8. The production method according to any one of claims 1 to 7, characterized in that: and 2) granulating in the step 2) by adopting a roller granulating or disc pelletizing mode.
9. The production method according to any one of claims 1 to 8, characterized in that: the composite iron-carbon sinter obtained in the step 3) also comprises a silicate binder phase.
10. The production method according to any one of claims 1 to 9, characterized in that: the microwave sintering in the step 3) is specifically as follows: and adopting one or more microwave sources, and heating and roasting the sintered green pellets after distribution by the microwave sources.
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