CN113388707A - Pulverized coal injection method and device for smelting reduction furnace - Google Patents
Pulverized coal injection method and device for smelting reduction furnace Download PDFInfo
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- 239000000843 powder Substances 0.000 claims abstract description 100
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- 229910052799 carbon Inorganic materials 0.000 claims abstract description 12
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- QMQXDJATSGGYDR-UHFFFAOYSA-N methylidyneiron Chemical compound [C].[Fe] QMQXDJATSGGYDR-UHFFFAOYSA-N 0.000 description 2
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0006—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
Abstract
The invention discloses a method and a device for injecting coal powder into a smelting reduction furnace, wherein the method comprises the steps of injecting a mixed material into a smelting pool by using a mixed spray gun for carburization, injecting a coarse-particle semi-coke agent by using a coal powder spray gun for reducing the generation of foam slag, injecting the coal powder into a secondary combustion area by using a smoldering spray gun for combustion and heat release, and injecting the coal powder into a gas chamber area by using a gas chamber spray gun for combustion and carbon neutralization, so that a systematic and three-dimensional coal powder injection process is formed.
Description
Technical Field
The invention relates to the field of non-blast furnace smelting iron making, in particular to a method and a device for injecting pulverized coal into a smelting reduction furnace.
Background
The blast furnace coal injection is a key technology for changing the energy structure of the blast furnace and is an effective energy-saving measure. The blast furnace coal injection mainly comprises a raw coal storage and transportation system, a coal powder preparation system, a coal powder conveying system, a coal powder injection system, a dry gas preparation system and a gas supply system. The blast furnace coal injection powder is the pulverized coal which is directly injected into the blast furnace from a blast furnace tuyere and is ground, coal is used for replacing coke, the resource shortage of coking coal can be relieved, heat can be provided and the pulverized coal can be used as a reducing agent, so that the coke ratio is reduced, the pig iron cost is reduced, the production capacity of a newly-built coke oven and coke can be reduced, the pollution of coking production to the environment is reduced, the blast furnace coal injection ratio is continuously increased, and the pulverized coal injection powder becomes an important means for energy conservation and emission reduction in the steel industry in recent years. The blast furnace coal injection has good economic and social benefits, so that the requirement that a newly built or modified blast furnace is provided with a coal injection facility is a necessary result. The blast furnace coal injection technology is generally applied in China, and more blast furnaces adopt the coal injection technology. However, due to the special skeleton action of the coke in the blast furnace, the pulverized coal injected into the blast furnace cannot completely replace the coke, and only can be beneficial supplement for cost reduction and efficiency improvement of the blast furnace.
At present, the non-blast furnace smelting reduction iron making technology also adopts a coal powder injection technology, but the technology is essentially different from the blast furnace coal injection technology. The research related to direct pulverized coal injection in smelting reduction iron making is less, the method is only limited to injection at a specific position, the research on the reaction process and mechanism in the furnace is less, and the efficient operation of production cannot be effectively guided. The pulverized coal injection at different positions on the smelting reduction furnace can have different functions, and the exploration and research of the pulverized coal injection on the smelting reduction furnace have great benefits on the reaction of a molten pool, the stable production, the stable coal gas heat value, the improvement of the utilization efficiency of the pulverized coal, the improvement of the temperature of a secondary combustion area and the like. Therefore, how to effectively carry out pulverized coal injection and how to control a pulverized coal injection technology in smelting reduction iron making is a problem which needs to be solved urgently at present.
Disclosure of Invention
The invention aims to provide a method and a device for systematically and three-dimensionally injecting pulverized coal into a smelting reduction furnace, aiming at the defects of the technology. Different pulverized coals are injected at different positions of the smelting reduction furnace by using different spray guns, so that the optimal pulverized coal injection effect is achieved.
The basic concept adopted by the invention is as follows:
a coal powder injection method for a smelting reduction furnace comprises the steps of injecting a mixed material into a molten pool by using a mixing spray gun for carburization, injecting a coarse-particle semi-coking agent by using a coal powder spray gun for reducing the generation of foam slag, injecting coal powder in a secondary combustion area by using a smoldering spray gun for combustion and heat release, and injecting coal powder in a gas chamber area by using a gas chamber spray gun for combustion and carbon neutralization, so that a systematically and three-dimensionally coal powder injection process is formed.
Furthermore, the mixing spray gun adopts a mode of mixing and directly spraying pulverized coal, quicklime powder, iron ore powder and dolomite powder, nitrogen is used as conveying gas to spray the mixture into the melting reduction furnace in a pneumatic conveying mode, the mixing spray gun is directly immersed in the slag layer to directly spray the mixture into iron liquid, and coal cracking, pulverized coal carburizing, iron ore powder melting, iron ore powder reducing and slagging are carried out.
Furthermore, the coal powder is anthracite, or the bituminous coal is mixed with the anthracite according to a certain proportion to form mixed coal, and the single-gun injection flux is as follows: 0-90t/h of iron ore powder, the coal powder injection amount is 0-40t/h, the injected coal powder granularity is less than 3mm, the water content is less than 2 percent, and the ash content is less than or equal to 5 percent. The inner diameter of the mixing spray gun is 175mm, the included angle between the mixing spray gun and the furnace body is 45 degrees, and the two mixing spray guns are symmetrically distributed on the furnace body.
Further, the temperature of the iron ore powder is 0-800 ℃, and the temperature of the coal powder is 0-100 ℃.
Furthermore, the pulverized coal spray gun is directly immersed in the slag layer to directly spray pulverized coal into molten iron, so that pulverized coal carburization and molten iron carbon supplement are carried out, and the pulverized coal spray gun is used as a semicoke agent to reduce foam slag.
Further, the single-gun injection flux of the pulverized coal injection gun is as follows: the coal powder injection amount is 0-20t/h, the coal powder temperature is 0-100 ℃, the coal is anthracite, semi-coke and coke powder, or semi-coke obtained by selecting cyclone dust collection and cloth bag dust collection, and the semi-coke contains TFe: 9-13%, CaO: 2-4% of SiO2：4-7％，Al2O3：3-6％，MgO：0.8-1.4％，TiO2：0.1-0.5％，P：0.01-0.12％，S：0.6-1.0％，Mn：0.1-0.15％，FeO：7-10％，Na2O：0.3-0.7％，K2O: 0.5-0.8%, ZnO: 0.08-0.12%; fixed carbon of the semicokeThe content is 60-70%, the ash content is 28-33%, the average grain diameter is 50-60um, and the moisture content of the semi-coke after drying is less than 2%; the inner diameter of the pulverized coal spray gun is 75mm, the included angle between the pulverized coal spray gun and the furnace body is 50 degrees, and the two pulverized coal spray guns and the mixing spray gun are symmetrically distributed on the furnace body on the same horizontal plane.
Furthermore, the smoldering spray gun adopts coal powder for blowing, and is arranged in a secondary combustion area at the upper part of the slag layer for burning the coal powder and increasing the temperature in the furnace; the pulverized coal of the braising spray gun needs to be sprayed by pulverized coal in order to fully combust the pulverized coal, the granularity of the sprayed pulverized coal is less than or equal to 200 meshes, the sprayed pulverized coal can be immediately combusted, and the spraying carrier gas is nitrogen, hydrogen-rich gas or oxygen and compressed air, and can be combusted or supplemented with oxygen.
Furthermore, the inner diameter of each braising spray gun is 30mm, the included angle between each braising spray gun and the furnace body is 60 degrees, the two braising spray guns are symmetrically distributed on the furnace body near the mixing spray gun, the total length of each braising spray gun is short, and the gun heads are positioned in a secondary combustion area; single gun blowing flux: the blowing amount of the pulverized coal is 0-20t/h, the temperature of the pulverized coal is 0-100 ℃, the coal can be anthracite, preferably bituminous coal, and the volatile content of the bituminous coal is more than or equal to 30%.
Further, drying and controlling the particle size by a crusher in the preparation of the granulated coal; the powdered coal is prepared by drying and controlling the granularity by a medium-speed coal mill.
Furthermore, the gas chamber spray gun is positioned at the other side of the inlet of the vaporization cooling flue, only one gas chamber spray gun is arranged, the included angle between the spray gun and the outer wall of the gas chamber is 60-120 degrees, and the single gun injection flux is as follows: the coal powder injection amount is 0-20t/h, the used raw coal is bituminous coal, the Ha's grindability coefficient of the raw coal is more than or equal to 40, and the granularity of the coal powder is as follows: 80 percent of coal powder is less than or equal to 200 meshes, the water content of dry coal powder is less than or equal to 2 percent, and the volatile component Vdaf of bituminous coal is between 20 and 40 percent.
Furthermore, the coal injection operation is effectively controlled, and the effect of accurately controlling the reactions of all parts in the furnace is achieved by changing the coal injection amount at different spray guns. Reducing the coal powder injection amount of the mixing spray gun under the condition of keeping normal coal powder carburization in the furnace; the blowing amount of the pulverized coal spray gun is increased to inhibit the generation of foam slag; the temperature of the combustion area is changed by adjusting the coal injection quantity of the smoldering lance.
Further, a device for realizing the method is provided.
Compared with the prior art, the invention has the following advantages:
a method and apparatus for omnibearing coal powder injection in smelting reduction furnace features that a mixing spray gun and a coal powder spray gun are immersed in slag layer to inject granular coal and semi-coke into molten pool, so having a certain impact depth. In order to reduce the production cost and the smooth process, the mixing spray gun is carried out by adopting a mode of spraying and blowing mixed coal powder with good carburization effect, and the coal powder spray gun is carried out by adopting a mode of spraying and blowing coarse-grain carbocoal. In the secondary combustion zone, powdery bituminous coal with good combustibility is blown into the MPR furnace through a smoldering lance, so that sufficient combustion heat release can be carried out. Powdered bituminous coal is blown to the inlet of the vaporization cooling flue from a gas chamber through a gas chamber spray gun, so that CO in the gas can be blown at high temperature2Is reduced to CO, so that the calorific value of the coal gas is increased. The reaction of each part in the furnace is accurately controlled by injecting different coal types and different coal injection quantities through different spray guns, different positions and different angles, and the stable and smooth production can be achieved.
It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.
Drawings
The above and other features, advantages and aspects of various embodiments of the present disclosure will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like or similar reference characters designate like or similar elements, and wherein:
FIG. 1 is a schematic view of an omnidirectional pulverized coal injection method and apparatus for a smelting reduction furnace according to the present invention.
FIG. 2 is a process flow diagram of an omnidirectional pulverized coal injection method for a smelting reduction furnace according to the present invention.
1-a mixing spray gun; 2-smoldering furnace spray gun; 3-a pulverized coal spray gun; 4-a gas chamber spray gun; 5-a hot air spray gun; 6-a gas chamber; 7-flue spray gun; 8-vaporizing and cooling the flue; 9-MPR furnace; 10-a secondary combustion zone; 11-slag layer; 12-iron aqueous layer.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are some, but not all embodiments of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
The omnibearing coal powder blowing method for smelting reduction furnace includes blowing granular coal into the smelting bath for carburization by means of mixing spray gun, blowing coarse-grain semi-coke agent to reduce the generation of foamed slag by means of coal powder spray gun, blowing coal powder in secondary combustion area by means of smoldering spray gun for heat release, and blowing coal powder in coal gas chamber area by means of coal gas chamber spray gun for combustion and carbon neutralization to form systematic and stereo coal powder blowing process. The coal dust injection position is different, and the action and the mechanism are also different.
Further, the coal is sprayed by the mixing spray gun, the mixing spray gun adopts a mode of mixing and directly spraying pulverized coal, quicklime powder, iron ore powder and dolomite powder, nitrogen is used as conveying gas to spray the mixture into the melting reduction furnace in a pneumatic conveying mode, the mixing spray gun is directly immersed in a slag layer to directly spray the mixture into molten iron, and coal cracking, pulverized coal carburization, iron ore powder melting, iron ore powder reduction and slagging are carried out. The coal can be anthracite, or the bituminous coal can be mixed with anthracite according to a certain proportion to form mixed coal, and the coal with good carburization effect is selected. Single gun blowing flux: 0-90t/h of mineral powder (the temperature of hot ore is 0-800 ℃), and the coal powder injection amount is 0-40t/h (the temperature of coal powder is 0-100 ℃). The inner diameter of the mixing spray gun is 175mm, the included angle between the mixing spray gun and the furnace body is 45 degrees, and the two mixing spray guns are symmetrically distributed on the furnace body. Guarantee under given pressure that the solid can effectual jetting advances in the molten iron and have a certain degree of depth, guarantee that the raw materials has sufficient time to melt the dissolution, realize the abundant carburization of buggy and reduction reaction, realize efficient spring heat transfer. The specific reaction equation is as follows:
coal pyrolysis → H2+CO+N2+CCoke (coke)； CCoke (coke)→[C]Iron；
Fe2O3+3[C]I iron＝2[Fe]Iron+3CO-Q (suction); fe3O4+4[C]Iron3Fe +4CO-Q (absorbtion);
FeO+[C]iron＝[Fe]Iron+ CO-Q (suction).
Furthermore, the coal powder spray gun for spraying coal is mainly different from the mixing spray gun only in that the coal powder is independently sprayed, and the coal powder spray gun is also directly immersed in a slag layer to directly spray the coal powder into molten iron for performing coal powder carburization, molten iron carbon supplement and serving as a semicoke agent to reduce foam slag. Single gun blowing flux: the coal powder injection amount is 0-20t/h (the coal powder temperature is 0-100 ℃), and the coal can be anthracite, semi-coke and coke powder, or semi-coke obtained by cyclone dust removal and cloth bag dust removal. The semicoke contains TFe: 9-13%, CaO: 2-4% of SiO2：4-7％，Al2O3：3-6％，MgO：0.8-1.4％，TiO2：0.1-0.5％，P：0.01-0.12％，S：0.6-1.0％，Mn：0.1-0.15％，FeO：7-10％，Na2O：0.3-0.7％，K2O: 0.5-0.8%, ZnO: 0.08-0.12%; the fixed carbon content of the semi-coke is 60-70%, the ash content is 28-33%, the average grain diameter is 50-60um, and the moisture content of the semi-coke after drying is less than 2%. The inner diameter of the pulverized coal spray gun is 75mm, the included angle between the pulverized coal spray gun and the furnace body is 50 degrees, and the two pulverized coal spray guns and the mixing spray gun are symmetrically distributed on the furnace body on the same horizontal plane.
Furthermore, the pulverized coal injected by the mixing spray gun and the pulverized coal spray gun needs to be injected by using granular coal in order to ensure that the pulverized coal reaches a certain injection depth, which is different from the pulverized coal injection of a blast furnace, and the pulverized coal injected into the blast furnace can be immediately combusted as the pulverized coal for the blast furnace is finer, which also determines the difference of pulverized coal preparation systems. The system for producing coal from granulated coal is dry coal powder obtained by crushing and drying raw coal by a crusher and collecting coal powder by cyclone dust removal and cloth bag dust removal. The granularity of the raw coal is between 2mm and 8mm, the proportion of the raw coal smaller than 2mm is not more than 10 percent, and the water content of the raw coal is not more than 10 percent. In order to reduce the raw material cost, the mixed coal of soft coal and anthracite is adopted, the coal with low sulfur, low ash content and good grindability is selected, and the proportion of the soft coal in the mixed coal is 20-60%. The particle size of the obtained dry coal powder is as follows: 90 percent of coal powder is less than or equal to 3mm, 80 percent of coal powder is less than or equal to 2mm, 50 percent of coal powder is less than or equal to 0.5mm, and the water content of dry coal powder is less than or equal to 2 percent and is controlled to be less than 1.5 percent as much as possible so as to reduce the blockage of the coal powder in a conveying pipeline and an injection pipeline.
Furthermore, the smoldering spray gun sprays coal, the smoldering spray gun adopts coal powder for spraying, and the smoldering spray gun burns the coal powder in a secondary combustion area at the upper part of the slag layer and improves the temperature in the furnace. The specific reaction equation is as follows: 2C(s) + O2(g) 2co (g) + Q (iso).
Furthermore, in order to fully combust the pulverized coal, the pulverized coal of the braising spray gun needs to be sprayed by pulverized coal injection, and the sprayed pulverized coal can be immediately combusted. The blowing carrier gas is nitrogen, hydrogen-rich gas or oxygen, compressed air, etc., and can be used for combustion or oxygen supplementation. The process for preparing coal from pulverized coal is different from that for preparing coal from granular coal, a pulverized coal preparation system is used for crushing and drying raw coal by a vertical medium-speed coal mill, the used raw coal is bituminous coal, and the water content is less than or equal to 12%. The particle size of the obtained dry coal powder is as follows: 80% of coal powder is less than or equal to 200 meshes, and the water content of dry coal powder is less than or equal to 2%. The finer the pulverized coal, the larger its specific surface area, and the more rapidly the combustion. The coal powder should meet the requirements of good combustion performance, low ignition temperature, strong reactivity and high calorific value. The inner diameter of each braising spray gun is 30mm, the included angle between the braising spray gun and the furnace body is 60 degrees, the two braising spray guns are symmetrically distributed on the furnace body near the mixing spray gun, the total length of the braising spray gun is short, and the head of the braising spray gun is positioned in a secondary combustion area. Single gun blowing flux: the blowing amount of the pulverized coal is 0-20t/h (the temperature of the pulverized coal is 0-100 ℃), and the coal can be anthracite, and is preferably bituminous coal.
Further, the secondary fuel rate is controlled by controlling the amount of coal powder injected by the smoldering lance. The afterburning rate being the CO and H leaving the metal melt2The ratio at which the space in and above the slag layer is burned again, namely:
the secondary combustion rate must be effectively controlled, when the secondary combustion rate is high, the energy must be effectively transferred to the molten pool, and the heat quantity taken away by the overflow of coal gas is reduced as much as possible, which is related to the factors of the spring heat exchange effect of the molten pool, the thickness of a slag layer, the temperature of molten iron and the like. The secondary combustion rate is about 50-60% generally, and the temperature of the combustion zone is kept stable and constant.
Furthermore, the gas chamber spray gun sprays coal, the gas chamber spray gun is positioned at the other side of the inlet of the vaporization cooling flue, only one gas chamber spray gun is arranged, and the included angle between the spray gun and the outer wall of the gas chamber is 60-120 degrees. Single gun blowing flux: the blowing amount of the pulverized coal is 0-20 t/h. The raw coal is bituminous coal which has higher volatile content and lower price than anthracite, and can be blown by bituminous coal with higher volatile content, so that a large amount of hydrocarbon can be generated, the gas reducing capability can be enhanced, and the heat value of the gas can be increased. As pulverized coal injection is adopted, the Ha's grindability coefficient of raw coal is required to be more than or equal to 40, thus being beneficial to pulverized coal grinding and long service life of equipment. The particle size of the obtained dry coal powder is as follows: 80% of coal powder is less than or equal to 200 meshes, and the water content of dry coal powder is less than or equal to 2%. The volatile component Vdaf of bituminous coal is 20% -40%, and H is produced by coal cracking2、CO、N2，CCoke (coke)The reaction equation is: coal pyrolysis → H2+CO+N2+CCoke (coke)。
Example 1
An omnibearing pulverized coal injection method for a smelting reduction furnace is completed by utilizing a smelting furnace and a device shown in figure 1. The method comprises the step of respectively blowing reducing agents through a mixing spray gun, a coal powder spray gun, a stewing spray gun and a gas chamber spray gun. Two mixing spray guns, two coal powder spray guns, two smoldering spray guns and a gas chamber spray gun are arranged on the MPR furnace body.
1. Mixed spray gun blowing
The mixing spray gun adopts a mode of directly spraying and blowing the mixture of coal powder, quicklime powder, iron ore powder and dolomite powder, and the spraying flux of a single gun is as follows: the blowing amount of the mineral powder is 72t/h, and the hot ore temperatureThe temperature is 400 ℃; the coal powder injection amount is 20t/h, the coal powder temperature is 95 ℃, and the injection air amount is 5000m3H is used as the reference value. The coal powder for injection is mixed coal, the ratio of bituminous coal is 30%, and the specific industrial analysis of the anthracite and the bituminous coal is as follows:
the industrial analysis of anthracite coal is: 5.04% of ash, 7.23% of volatile matter, 87.06% of fixed carbon, 0.31% of sulfur, 46.61 of Hawski grindability coefficient, 7401kcal/kg of lower calorific value, 67.12% of particle size of 2-8 mm and 7.61% of raw coal moisture.
The industrial analysis of bituminous coal was: 6.25 percent of ash, 39.56 percent of volatile matter, 48.26 percent of fixed carbon, 0.39 percent of sulfur, 5369kcal/kg of low calorific value and 5.93 percent of raw coal moisture.
2. Pulverized coal injection by spray gun
The pulverized coal spray gun only uses pulverized coal for independent injection, the pulverized coal is semicoke, the injection amount of the pulverized coal is 10t/h, the temperature of the pulverized coal is 95 ℃, and the injection amount is 1300m3The industrial analysis of the semicoke is:
TABLE 1 semicoke chemical composition (wt/%)
TABLE 2 Industrial analysis of semicoke (%)
3. Smoldering furnace spray gun blowing
The smoldering spray gun only uses coal powder to carry out independent blowing, the blowing carrier gas is compressed air, the oxygen content is 21 percent, and the blowing air quantity is 1000m3The pulverized coal is selected from bituminous coal, the pulverized coal injection amount is 10t/h, the pulverized coal temperature is 95 ℃, the secondary combustion rate is 60%, and the industrial analysis of the bituminous coal is as follows:
ash content of 2.91%, volatile matter of 33.26%, fixed carbon of 51.76%, sulfur content of 1.35%, lower calorific value of 5756kcal/kg, and raw coal moisture of 2.91%.
4. Gas chamber spray gun blowing
The spray gun of the gas chamber only uses coal powder to carry out independent injection, the injection carrier gas is coke oven gas, and the injection gas amount is 300m3The pulverized coal is selected from bituminous coal, the injection amount of the pulverized coal is 10t/h, the temperature of the pulverized coal is 95 ℃, and the industrial analysis of the bituminous coal is as follows:
4.55% of ash, 34.23% of volatile matter, 54.38% of fixed carbon, 1.07% of sulfur, 6184kcal/kg of low-grade heat value and 6.85% of raw coal moisture.
The component of the injected coke oven gas is H2：60％，CH4：25％，CO：8％，CO2：2％，N2：5％。
In the description of the present application, the description of the terms "one embodiment," "some embodiments," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (9)
1. A coal powder injection method for a smelting reduction furnace is characterized by comprising the steps of injecting a mixed material into a molten pool by using a mixing spray gun for carburization, injecting a coarse-particle semi-coking agent by using a coal powder spray gun for reducing the generation of foam slag, injecting coal powder in a secondary combustion area by using a smoldering spray gun for combustion and heat release, and injecting the coal powder in a gas chamber area by using a gas chamber spray gun for combustion and carbon neutralization, so that a systematically and three-dimensionally coal powder injection process is formed.
2. The pulverized coal injection method for a smelting reduction furnace according to claim 1, wherein the mixing lance is used for directly injecting the mixture of pulverized coal, quicklime powder, iron ore powder and dolomite powder by mixing, nitrogen is used as a conveying gas to inject the mixture into the smelting reduction furnace by pneumatic conveying, the mixing lance is directly immersed in a slag layer to directly inject the mixture into iron liquid, and the coal cracking, the pulverized coal carburizing, the iron ore powder melting, the iron ore powder reducing and the slagging are performed.
3. The pulverized coal injection method for a smelting reduction furnace according to claim 2, wherein the pulverized coal is anthracite, or the bituminous coal is mixed with the anthracite in a certain ratio to form mixed coal, and the single-gun injection flux is as follows: 0-90t/h iron ore powder, the coal powder injection amount is 0-40t/h, the inner diameter of the mixing spray gun is 175mm, the included angle with the furnace body is 45 degrees, and the two mixing spray guns are symmetrically distributed on the furnace body.
4. The method for injecting pulverized coal into a smelting reduction furnace according to claim 3, wherein the temperature of iron ore powder is 0 to 800 ℃, the temperature of pulverized coal is 0 to 100 ℃, the pulverized coal injection lance is directly immersed in the slag layer to directly inject pulverized coal into molten iron, and the pulverized coal is carburized, the molten iron is supplemented with carbon, and the pulverized coal is used as a semicoke agent to reduce foaming slag.
5. The pulverized coal injection method for a smelting reduction furnace according to claim 4, wherein a single-lance injection flux of the pulverized coal injection lance is: the coal powder injection amount is 0-20t/h, the coal powder temperature is 0-100 ℃, the coal is anthracite, semi-coke and coke powder, or semi-coke obtained by selecting cyclone dust collection and cloth bag dust collection, and the semi-coke contains TFe: 9-13%, CaO: 2-4% of SiO2：4-7％，Al2O3：3-6％，MgO：0.8-1.4％，TiO2：0.1-0.5％，P：0.01-0.12％，S：0.6-1.0％，Mn：0.1-0.15％，FeO：7-10％，Na2O：0.3-0.7％，K2O: 0.5-0.8%, ZnO: 0.08-0.12%; the fixed carbon content of the semi-coke is 60-70%, the ash content is 28-33%, the average grain diameter is 50-60um, and the moisture content of the semi-coke after drying is less than 2%; the inner diameter of the pulverized coal spray gun is 75mm, the included angle between the pulverized coal spray gun and the furnace body is 50 degrees, and the pulverized coal spray gun and the furnace body are totally two coalsThe powder spray gun and the mixing spray gun are symmetrically distributed on the furnace body on the same horizontal plane.
6. The pulverized coal injection method for a smelting reduction furnace according to claim 5, wherein the smoldering lance injects pulverized coal, and the smoldering lance burns pulverized coal in a secondary combustion area at the upper part of the slag layer to increase the temperature in the furnace; the pulverized coal of the braising spray gun needs to be sprayed by pulverized coal in order to fully combust the pulverized coal, the sprayed pulverized coal can be immediately combusted, and the spraying carrier gas is nitrogen, hydrogen-rich gas or oxygen, and compressed air, and can be combusted or supplemented with oxygen.
7. The pulverized coal injection method for a smelting reduction furnace according to claim 6, wherein the inner diameter of the annealing lance is 30mm, the included angle with the furnace body is 60 degrees, two annealing lances are symmetrically distributed on the furnace body near the mixing lance, the total length of the annealing lances is short, and the lance head is located in the secondary combustion area; single gun blowing flux: the blowing amount of the pulverized coal is 0-20t/h, the temperature of the pulverized coal is 0-100 ℃, and the coal can be anthracite, preferably bituminous coal.
8. The pulverized coal injection method for a smelting reduction furnace according to claim 7, wherein the gas chamber lance is located at the other side of the inlet of the vaporization cooling flue, only one gas chamber lance is provided, an included angle between the lance and the outer wall of the gas chamber is 60 ° to 120 °, and a single lance injection flux: the coal powder injection amount is 0-20t/h, the used raw coal is bituminous coal, the Ha's grindability coefficient of the raw coal is more than or equal to 40, and the granularity of the coal powder is as follows: 80 percent of coal powder is less than or equal to 200 meshes, the water content of dry coal powder is less than or equal to 2 percent, and the volatile component Vdaf of bituminous coal is between 20 and 40 percent.
9. Apparatus for carrying out the method of claims 1 to 8.
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