CN101736103B - Iron manufacture technology - Google Patents

Abstract

The invention belongs to the technical field of metallurgy and relates to an ironmaking process. In the present invention, a direct reduction furnace is configured outside the blast furnace type reduction gasifier; the iron-containing furnace charge is a mixed ore of ordinary powder ore/lump ore/pellet, which is produced into hot direct reduced iron by the direct reduction furnace; coke, hot state Direct reduced iron is added from the top of the blast furnace-type reduction gasifier; oxygen and coal powder are injected from the oxygen tuyere of the blast furnace-type reduction gasifier to produce high-quality hot metal, water slag and high-quality gas. The products output by this process are high-quality hot metal, water slag and high-quality gas. The SDORBF ironmaking process has no dust, no waste liquid, and no waste gas emissions. The invention does not require sintering, and only uses a small amount of coke and oxygen, thereby greatly reducing the amount of coke used and the cost of molten iron. This process can be widely used in the production of hot metal.

Description

an iron-making process

technical field

The invention belongs to the technical field of metallurgy and relates to an ironmaking process. the

Background technique

The main body of modern ironmaking, blast furnace ironmaking, can be said to have reached its peak in terms of theory and technology, and has reached a very perfect level. However, the blast furnace ironmaking method has disadvantages such as the need to use coke, long process, large investment, and serious environmental pollution. the

my country's energy consumption is dominated by coal, accounting for roughly 70% of the total energy consumption. Although coal resources are abundant (the proven recoverable amount is more than 600 billion tons), coking coal accounts for only 6%, and the distribution is uneven (coking coal resources in Shanxi Province account for more than 50%). Therefore, it is obviously unrealistic for the development of my country's ironmaking production to be entirely based on the massive consumption of coking coal. The lack of coking coal and the improvement of people's environmental protection requirements have forced people to carry out research on new ironmaking processes. For the blast furnace ironmaking method, due to the development of coal injection technology, especially the oxygen-enriched (or full oxygen) large coal injection technology, the coke ratio of the blast furnace will be greatly reduced (the coke ratio will drop below 300kg/t, and the coal ratio will be reduced to 200kg /t or more), thus injecting new vitality into the blast furnace ironmaking method. However, if the coke ratio is to be further reduced, such as the coke ratio falls below 200kg/t, the coal ratio should be injected above 300kg/t. The difficulty is revealed: the first is insufficient performance of heat in the furnace; the second is the increase of unburned coal in the furnace. As a result, blast furnace operation is difficult. the

If the high-efficiency clean coal gasifier and the direct reduction shaft furnace are used to connect the process, a non-coking coal pulverized coal is used to produce sponge iron. Sponge iron is used as a raw material for electric furnaces to produce high-quality steel. This process is feasible, but it has the following disadvantages: ①Sponge iron is a solid state, and it is used as a raw material for producing high-quality steel in an electric furnace. Therefore, the iron-containing charge for producing sponge iron must be high-quality lump ore or pellets, which are difficult to obtain in China. ②The high-temperature reducing gas (1200-1700℃, containing dust and H2S) produced by the coal gasification furnace (such as shell process) cannot be directly used in the direct reduction shaft furnace, and must be cooled, dust removed, and desulfurized before being sent to the direct reduction shaft furnace for use . ③ The coal gas treatment process for processing the high-temperature reducing gas produced by the coal gasifier (such as the shell process) into a qualified reducing gas that meets the requirements of the direct reduction shaft furnace process is extremely complicated and costly. the

Smelting reduction technology is one of several cutting-edge high-techs in the iron and steel industry. It is a new process for producing hot metal from coal and ore. Due to the characteristics of no or less use of coke, good environmental protection, low energy consumption, low investment, and strong adaptability, this method has attracted the attention of countries all over the world. According to statistics, so far there have been 35 kinds of smelting reduction methods, of which 13 are more competitive. Only a few smelting reduction processes such as COREX, FINEX, FINMET and HIsmelt have industrial production scale. But so far, only the COREX and FINEX ironmaking methods have been put into industrial scale production. COREX ironmaking uses lump ore, pellets or sinter as iron-containing charge, and directly uses lump coal as energy. The pre-reduction and final reduction of iron oxides are carried out in two reaction devices, the pre-reduction shaft furnace and the melter-gasifier respectively. The melter gasifier in the COREX unit comes with a so-called "coking plant", that is, there is a coking process of coal in the melter gasifier, so that a so-called coke bed can be formed in the furnace, because of this coke In order to increase the temperature of the molten iron and control the composition of the molten iron, it can produce molten iron similar to a blast furnace. The COREX device has the disadvantages that lump ore and lump coal must be used and the structure is huge. FINEX is a new melting reduction process, which uses non-coking coal as energy and reducing agent to smelt iron-bearing fine ore to produce hot molten iron similar to blast furnace or COREX furnace. FINEX process is developed on the basis of COREX process. The process is divided into two parts. First, the fluidized bed is used to reduce the ore powder into direct reduced iron, and then the solid sponge iron is melted, deeply reduced, heated, and the composition of the molten iron is adjusted by the melter gasifier of the COREX furnace, and finally high-quality molten iron is obtained. , At the same time, high-quality reduced gas with suitable temperature and chemical composition can be obtained. the

The FINEX process also has the following disadvantages:

a The raw material of the FINEX process is iron-containing fine ore (-8mm sintered iron-containing material), and the powdered sponge iron produced by the FINEX fluidized bed needs to be briquetted before being fed into the COREX gasifier. the

b The FINEX process still uses lump coal or pulverized coal briquettes. the

Contents of the invention

The object of the present invention is to provide a kind of ironmaking process. A direct reduction furnace is installed outside the blast furnace-type reduction gasifier; the iron-containing charge is a mixed ore of ordinary powder ore/lump ore/pellet, which is produced by the direct reduction furnace into hot direct reduced iron; coke, hot direct reduced iron Feed from the top of the blast furnace type reduction gasifier; oxygen and coal powder are injected from the oxygen tuyere of the blast furnace type reduction gasifier to produce high-quality hot metal, water slag and high-quality gas. The present invention does not require sintering, and only uses a small amount of coke and oxygen. Thereby greatly reducing the amount of coke used and the cost of molten iron. the

The present invention is a new non-blast furnace ironmaking process created on the basis of blast furnace oxygen-enriched (or full oxygen) large coal injection process, smelting reduction process, coal gasification furnace and direct reduction shaft furnace connection process ——SDORBF ironmaking process. the

SDORBF ironmaking process is divided into two parts: blast furnace type reduction gasifier and direct reduction furnace. the

The direct reduction furnace uses the high-quality reduction gas provided by the blast furnace type reduction gasifier to produce the mixed ore of iron-containing charge common powder ore/lump ore/pellet into hot direct reduced iron or hot briquetted sponge iron. the

The function of the blast furnace type reduction gasifier is to perform final reduction, heating and melting of the added hot direct reduced iron or hot briquette, store the melted slag and iron in the hearth, realize the separation of slag and iron, adjust the composition of molten iron, and regularly discharge molten iron and slag. During the process of falling in the furnace, the coke is heated by the high-temperature reducing gas, and the hot coke (~1800°C.) floats on the surface of the liquid slag iron to form a hot dynamic coke bed. The hot coke bed plays the role of raising the temperature of the molten iron and slag passing through the bed, and carburizing the molten iron. Another function of the blast furnace-type reduction gasifier is to provide high-quality reduction gas for the direct reduction furnace. the

The blast furnace type reduction gasifier is completely different from the gasifiers of COREX and FINEX. The lump coal or briquette fed from the top of the gasifier in the COREX and FINEX devices has a coal coking process, and the tar produced during the coal gasification must be burned to ensure the smooth progress of the process. Therefore, the top of the gasifier of COREX and FINEX must adopt a large ball vault structure, and the temperature of the reduced gas at the outlet of the gasifier of COREX and FINEX must be kept ≥ 1050 °C. The reduction gas temperature must be lowered to ~850°C before it can be used by the direct reduction furnace. As a result, the gasifiers of COREX and FINEX have a large structure and high energy consumption. Coke is added from the top of the blast furnace type reduction gasifier, there is no gasification and coking process of lump coal or briquette, the top does not need to be designed with a large spherical vault structure, and it is not necessary to maintain the temperature of the reduction gas at the gasifier outlet ≥ 1050 °C. the

Blast furnace type reduction gasifier adopts a furnace type similar to that of a blast furnace. However, the output furnace top gas is high-temperature reduction gas, and the temperature of the reduction gas is adjustable. Blast furnace-type reduction gasifier outputs ~850°C reduced coal gas, which is directly fed into the direct reduction furnace of SDORBF after hot cyclone dedusting. The dust collected by the cyclone dust collector is sprayed from the blast furnace-type reduction gasifier oxygen tuyere through the dust injection system. SDORBF direct reduction furnace top output high-quality gas. the

Furnace top gas cleaning process adopts dry dust removal. The gas ash and the dust collected at each dust production point of this process are sprayed into the blast furnace through the dust injection system. the

The products output by SDORBF ironmaking process are: high-quality hot metal, water slag, and high-quality gas. the

The SDORBF ironmaking process has no dust, no waste liquid, and no waste gas emissions. the

Description of drawings

Accompanying drawing is the flowchart of the present invention

Among them, item 1 is a blast furnace type reduction gasifier, item 2 is a fluidized bed reduction furnace, item 3 is a hot briquette system, item 4 is a heat-resistant belt, item 5 is a coke loading equipment, and item 6 is a reducing gas gas pipe , item 7 is a hot cyclone dust collector, item 8 is a furnace top gas dry dust collector, item 9 is a TRT, item 10 is a dust collection tank, item 11 is a dust injection tank, item 12 is a coke feeding system, and item 13 is a block Shape flux feeding system, item 14 is reducing gas heating system, item 15 is dust/coal powder distributor, item 16 is dust mixer, item 17 is nitrogen/coal gas system for dust conveying, item 18 is blast furnace tuyere, item 19 Oxygen pipeline, item 20 is molten iron, item 21 is blast furnace slag, item 22 is blast furnace water slag flushing system, item 23 is dryer, item 24 is fine ore, limestone powder and dolomite powder, item 25 is coal powder bin, item 26 is a tundish, piece 27 is a spray tank, piece 28 is a mixer, piece 29 is pressurized gas, piece 30 is coal powder, piece 31 is dust, piece 32 is a feeding belt, and piece 33 is a reduction furnace top installation material equipment, part 34 is a blast furnace type reduction gasifier iron hole. Item 35 is for exporting coal gas for CCPP, item 36 is for exporting coal gas for producing DRI, item 37 is for exporting coal gas for chemical industry, item 38 is for exporting coal gas for the recirculation system of this process, and item 39 is a reducing gas delivery pipe. the

Detailed ways

Embodiments of the present invention will be further described below in conjunction with accompanying drawings:

For the iron-containing charge, take the SDORBF ironmaking process using all fine ore as an example. the

The fine ore, limestone powder and dolomite powder 24 from the raw material field are dried by the dryer 23, and the iron-containing fine ore and powdery flux with a particle size of 0-8 mm are sent to the fluidized bed via the feeding belt 32 and the top charging equipment 33 of the reduction furnace. Reduction furnace 2 loading. The fluidized bed reduction furnace 2 is divided into four stages R4, R3, R2, R1; the reduced coal gas produced by the blast furnace type reduction gasifier 1 delivered by the reducing gas delivery pipe 39 will pass through the fluidized bed reduction furnace 2 stages of fluidized beds R4, R3, The iron-containing fine ore in R2 and R1 is reduced to sponge iron, and the temperature of the sponge iron discharged from the fluidized bed R1 is 700°C. the

Sponge iron is briquetted by hot briquetting system 3 in hot state. The hot briquette sponge iron produced by the fluidized bed 2 is directly loaded from the top charging equipment of the blast furnace type reduction gasifier 1 through the heat-resistant belt 4. the

The task of the blast furnace type reduction gasifier 1 is to melt the sponge iron and obtain qualified molten iron, and at the same time produce reducing gas that meets the requirements of the fluidized bed reduction furnace 2 . The hot briquetted sponge iron is added from the top of the blast furnace type reducing gasifier 1 through the heat-resistant belt 4, coke 12 through the coke loading equipment 5 and the bulk flux feeding system 13, and the pulverized coal 30 and oxygen 19 are fed from the blast furnace type reducing gas Furnace 1 oxygen tuyere 18 sprays into. The dust collected by the hot cyclone dust collector 7 is returned to the blast furnace type reduction gasifier 1 . the

The function of the blast furnace type reduction gasifier 1 is to perform final reduction, heating and melting of the added hot direct reduced iron or hot briquette, store the melted slag and iron in the hearth, realize the separation of slag and iron and adjust the composition of molten iron, The iron gate 34 discharges the molten iron 20 and the slag 21 . The slag 21 is washed into water slag through the slag flushing system. The coke 12 is heated by the high-temperature reducing gas during the descent in the furnace, and the hot coke (~1800°C.) floats on the surface of the liquid slag iron to form a hot dynamic coke bed. The hot coke bed plays the role of raising the temperature of the molten iron and slag passing through the bed, carburizing the molten iron, and finally reducing it. the

The temperature of the reducing gas 6 derived from the blast furnace-type reducing gasifier 1 is 800-850°C, and the temperature of the reducing gas 6 at 800-850°C can be obtained through the control of operating parameters, such as adjusting the height of the reducing gasification charge surface, adjusting the amount of coal injection, Adjust the amount of steam injected into the top and more. The reducing gas 6 at 800-850°C is dedusted by the hot cyclone dust collector 7, and then sent to the RI fluidized bed of the fluidized bed 2 after being processed by the reducing gas delivery pipe 39 to the heater 14. The reducing gas passes through the fluidized beds R1, R2, R3, and R4 at all levels of the fluidized bed reduction furnace 2, and the iron-containing fine ore is processed into sponge iron; while the reducing gas is processed into the top gas by the iron-containing charge, and the top gas is produced by R3/R4 export. Top coal gas adopts dry dust removal 8, and the dust collected by dry dust removal 8 is sent to the pulverized coal bin 25 of the pulverized coal injection system through the pneumatic conveying system 31. The coal gas dedusted by the dry dust collector 8 adopts TRT9 to generate electricity and recover the top pressure energy of the furnace. Pieces 35-38 are options for exporting gas usage. Part 35 is for exporting coal gas for CCPP, part 36 is for exporting coal gas for producing DRI, part 37 is for exporting coal gas for chemical industry, and part 38 is for exporting coal gas for the recirculation system of this process. the

The dust collected by the hot cyclone dust collector 7 is loaded into a dust collection tank 10 . The dust collecting tank 10 packs the powder into the dust blowing tank 11 . The powder in the spray tank is sprayed from the blast furnace tuyere 18 through the mixer 16 and the dust distributor 15 . The dust injection aid gas adopts nitrogen or furnace top gas pressurized gas 17 . the

The dust collected at each dust producing point of this process and the dust collected by dry dust removal 8 are sent to the pulverized coal bin 25 of the pulverized coal injection system through the pneumatic conveying system 31, and the pulverized coal 30 produced by the pulverizing system is also sent into the pulverized coal bin 25 . The pulverized coal and dust in the pulverized coal bin 25 are sprayed into by blast furnace tuyere 18 through equipment such as tundish tank 26, injection tank 27, mixer 28, distributor 15 and the like. The blasting aid gas adopts nitrogen or coal gas pressurized gas 29 . the

A blast furnace type reduction gasifier can be equipped with multiple direct reduction furnaces. the

The iron-containing charge can also be a mixed ore of powder ore/lump ore/pellet, or one of them. When lump ore/pellet is used, the lump ore/pellet is added to the direct reduction furnace to produce hot reduced iron; when only fine ore is used, the fine ore is added to the fluidized bed reduction furnace 2 to generate hot briquetted sponge iron. The hot reduced iron or hot briquette is sent to the blast furnace type reduction gasifier 1 to produce hot molten iron. the

The products output by this process are: high-quality hot metal, water slag, and high-quality gas. the

The SDORBF ironmaking process has no dust, no waste liquid, and no waste gas emissions. the

The present invention does not require sintering, and only uses a small amount of coke and oxygen. Thereby greatly reducing the amount of coke used and the cost of molten iron. This process can be widely used in the production of hot metal.

Claims (12)

1. An ironmaking process, characterized in that: a direct reduction furnace is configured outside the blast furnace type reduction gasifier; the iron-containing charge is a mixed ore of ordinary fine ore/lump ore/pellet, which is produced by the direct reduction furnace into heat State direct reduced iron; coke and hot direct reduced iron are added from the top of the blast furnace type reduction gasifier; oxygen and coal powder are injected from the oxygen tuyere of the blast furnace type reduction gasifier to produce high-quality hot metal, water slag and high-quality gas. 2. The ironmaking process according to claim 1, characterized in that: the blast furnace type reducing gasifier is equipped with a direct reduction furnace in addition to a fluidized (fluidized) bed direct reduction furnace using powdered ore, and the iron-containing charge can be Only fine ore is used and hot briquetted direct reduced iron is produced by a flowing or fluidized bed direct reduction furnace using fine ore. 3. The ironmaking process according to claim 1, characterized in that: the coal gas output from the blast furnace-type reduction gasifier is a high-temperature reducing gas with adjustable gas temperature, and the reduced gas output at ~850°C is directly used by the direct reduction furnace. 4. The ironmaking process according to claim 1, characterized in that ≤200kg/t coke is used, and the coke is heated by high-temperature reducing gas to form a hot dynamic coke bed at ~1800°C floating on the liquid slag iron surface. It also includes coke consumption ≥ 200kg/t. 5. The ironmaking process according to claim 1, characterized in that: the furnace top gas cleaning process adopts dry dust removal. 6. The ironmaking process according to claim 1, characterized in that: gas ash and dust collected at each dust producing point are injected into the blast furnace through a pulverized coal injection system. 7. The ironmaking process according to claim 1, characterized in that various fluxes, such as limestone powder, dolomite powder or mixed powder of flux and ore, are sprayed from the tuyere of the blast furnace. 8. The ironmaking process according to claim 2, characterized in that: the top gas exported from the fluidized bed direct reduction furnace is dedusted by dry method, the dedusted gas is generated by TRT, and the gas is output after recovering the pressure energy of the top gas. 9. The ironmaking process according to claim 8, characterized in that: the output gas is used for CCPP, for producing DRI, for chemical industry, and for the recirculation system of this process. 10. The ironmaking process according to claim 1, characterized in that: the blast furnace type reduction gasifier is similar to the blast furnace type, and there is no large ball vault structure on the top. 11. The ironmaking process according to claim 1, characterized in that one blast furnace type reduction gasifier is equipped with multiple direct reduction furnaces. 12. The ironmaking process according to claim 1, characterized in that nitrogen or coal gas pressurized gas is used as the injection aid gas.

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