CN109536663B - Rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method - Google Patents
Rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method Download PDFInfo
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- CN109536663B CN109536663B CN201811627751.0A CN201811627751A CN109536663B CN 109536663 B CN109536663 B CN 109536663B CN 201811627751 A CN201811627751 A CN 201811627751A CN 109536663 B CN109536663 B CN 109536663B
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- 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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
Abstract
The invention discloses a rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method, belongs to the technical field of non-blast furnace iron-making, and solves the problems that the non-blast furnace iron-making process in the prior art is high in fuel ratio and cannot be produced in a large scale at low cost. The ironmaking method comprises the following steps: adding iron ore powder and a flux into a rotary kiln according to a designed proportion, and directly reducing the iron ore powder in the rotary kiln by heating and gas-based reduction to generate kiln tail gas to obtain pre-reduced furnace burden; the pre-reduction furnace charge is directly hot-charged into an oxy-fuel bath smelting furnace, mixed gas of coal powder and oxygen is sprayed into the oxy-fuel bath smelting furnace, the pre-reduction furnace charge is stirred, final reduction and slag-iron separation are carried out, smelting furnace gas is generated, and slag and molten iron are obtained; and mixing the generated kiln tail gas with the smelting furnace gas to obtain mixed gas, and circulating the mixed gas to the kiln head of the rotary kiln for pre-reducing the iron ore powder in the rotary kiln. The iron-making method of the invention can be used for reducing iron ore powder.
Description
Technical Field
The invention designs a non-blast furnace ironmaking technology, in particular to a rotary kiln gas-based reduction-total oxygen molten pool smelting ironmaking method.
Background
Blast furnace iron making is the most important iron making process in the world at present, and has the characteristics of large production scale, low energy consumption, good pig iron quality, high efficiency and the like.
At present, the non-blast furnace ironmaking process known as less coke or no coke mainly comprises a COREX process, a FINEX process and a HISMELT process, only the COREX process is used for realizing industrial production, and the FINEX process and the HISMELT process of Korea pump are still tried.
From the COREX production condition, although the coke ratio can be reduced by a small amount, the coal ratio is greatly increased, and the fuel ratio is far higher than that of a blast furnace ironmaking process. For the FINEX process, only korean purpy steel owns the technology, and its actual smelting parameters are not known for the reason of technical secrecy. The main reasons are that the reduction process of the powder ore fluidized bed is difficult to control, the reduced powder needs to be pressed into balls and hot charged into a melting furnace, and the process connection is difficult.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a rotary kiln gas-based reduction-total oxygen bath smelting iron-making method, which solves the problems of high fuel ratio and incapability of large-scale low-cost production of non-blast furnace iron-making processes in the prior art.
The purpose of the invention is mainly realized by the following technical scheme:
the invention provides a rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method, which comprises the following steps:
step 1: adding iron ore powder and a flux into a rotary kiln according to a designed proportion, and directly reducing the iron ore powder in the rotary kiln by heating and gas-based reduction to generate kiln tail gas to obtain pre-reduced furnace burden;
step 2: the pre-reduction furnace charge is directly hot-charged into an oxy-fuel bath smelting furnace, mixed gas of coal powder and oxygen is sprayed into the oxy-fuel bath smelting furnace, the pre-reduction furnace charge is stirred, final reduction and slag-iron separation are carried out, smelting furnace gas is generated, and slag and molten iron are obtained; and mixing the generated kiln tail gas with the smelting furnace gas to obtain mixed gas, and circulating the mixed gas to the kiln head of the rotary kiln for pre-reducing the iron ore powder in the rotary kiln.
In a possible design, in step 1, iron ore powder and a flux are premixed according to a designed proportion, and are added into a rotary kiln after being uniformly mixed.
In one possible design, in step 2, the oxygen is pure oxygen gas or oxygen-enriched gas.
In a possible design, in step 2, the kiln tail gas is dedusted by a deduster and then mixed with the produced smelting furnace gas.
In one possible design, a heat exchanger is adopted to exchange heat with the kiln tail gas before the kiln tail gas is dedusted, so that the temperature of the kiln tail gas is reduced to the temperature required by dedusting of the deduster.
In one possible design, the kiln tail gas after dust removal is subjected to CO removal2And then mixed with the produced smelting furnace gas.
In one possible design, kiln tail gas heating before dust removal is used to remove CO2And (4) heating the kiln tail gas to 400-500 ℃.
In one possible design, the dust collected by the dust remover from the kiln tail gas is injected into the oxy-fuel bath smelting furnace.
In one possible design, the mixed gas exchanges heat with the pre-reduction furnace charge discharged from the kiln head of the rotary kiln in the process of introducing the mixed gas into the kiln head of the rotary kiln, so that the temperature of the pre-reduction furnace charge is increased.
In one possible design, the temperature of the kiln tail gas is 600-800 ℃, the temperature of the smelting furnace gas is 1300-1600 ℃, and the temperature of the mixed gas is 700-1000 ℃.
Compared with the prior art, the invention has the following beneficial effects:
a) the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the invention can directly adopt fine ores as iron ore raw materials, saves raw material pretreatment processes such as sintering, pelletizing and the like, and has the advantages of low capital investment and short construction period; the smelting speed is high, the production efficiency is high, and the production cost is low; the heat energy and the chemical energy of the coal gas are completely recycled; high automation degree and less pollutant discharge.
b) In the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the invention, the reduction coal gas of the rotary kiln is smelting furnace gas generated by a total oxygen molten pool smelting furnace and kiln tail coal gas of the rotary kiln, wherein the smelting furnace gas comprises CO + H in percentage by volume2 70～80％、CO220-30% of kiln tail gas, and the volume percentage of the kiln tail gas is CO + H2 45～55％、CO225-35%, and the balance being dust, wherein Fe can be realized by utilizing CO in smelting furnace gas and kiln tail gas2O3And FeO, and can also reduce the tail gas emission of the ironmaking device.
c) According to the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the invention, as the temperature of the top gas of the total oxygen molten pool smelting furnace is higher (up to about 1500 ℃), and the temperature of the top gas directly introduced into the rotary kiln is too high, the furnace burden of the rotary kiln can be melted or formed, so that the temperature of the gas mixed with the top gas of the rotary kiln is reduced to the proper temperature (700-1000 ℃) for gas-based reduction of iron ore powder by utilizing the recycling gas at the tail of the rotary kiln for recycling and cooling, and then the top gas is introduced.
d) According to the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the invention, because the reduction of iron oxide and coal gas in the rotary kiln is an exothermic reaction, the rotary kiln does not need to be heated externally, and the high-efficiency reduction in the rotary kiln can be realized only by controlling the temperature of the coal gas entering the rotary kiln within the range of 700-1000 ℃.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
Fig. 1 is a schematic structural diagram of a rotary kiln prereduction-total oxygen bath smelting iron-making device provided by the second embodiment of the invention;
fig. 2 is a schematic structural diagram of a rotary kiln in a rotary kiln prereduction-total oxygen molten pool smelting iron-making device provided by the second embodiment of the invention;
fig. 3 is a schematic structural diagram of a shoveling plate and a bending part in the rotary kiln prereduction-total oxygen molten pool smelting iron-making device provided by the second embodiment of the invention;
fig. 4 is a front view of a shoveling plate and a bending portion in the rotary kiln prereduction-total oxygen molten pool smelting iron-making device provided by the second embodiment of the invention.
Reference numerals:
1-iron ore fines storage; 2-a flux bin; 3-a rotary kiln; 4-a blanking pipe; 5-total oxygen molten pool smelting furnace; 6-a pulverized coal bunker; 7-a hot metal ladle; 8-a slag pot; 9-an oxygen tank; 10-a heat exchanger; 11-a dust remover; 12-CO2A remover; 13-a mixing bin; 14-kiln tail gas flow valve; 15-furnace gas flow valve of the smelting furnace; 16-a housing; 17-insulating bricks; 18-a liner; 19-a shoveling plate; 20-bending part; d, the length of the shoveling plate; d-length of the bending part; l-the width of the shoveling plate; the angle between the alpha-shoveling plate and the liner in the radial direction.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.
Example one
The embodiment provides a rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method, which comprises the following steps:
step 1: adding iron ore powder and a flux into a rotary kiln through a belt according to a designed proportion, and directly reducing the iron ore powder in the rotary kiln by heating and gas-based reduction to generate kiln tail gas to obtain a pre-reduced furnace charge;
step 2: the pre-reduction furnace charge is directly hot-charged into an oxy-fuel bath smelting furnace, mixed gas of coal powder and oxygen is injected into the oxy-fuel bath smelting furnace, the pre-reduction furnace charge is intensively stirred, final reduction and slag-iron separation are carried out, smelting furnace gas is generated, slag and molten iron are obtained, and after the molten iron is accumulated to a certain amount, an iron notch is opened to discharge the molten iron and the slag; and mixing the generated kiln tail gas with the smelting furnace gas to obtain mixed gas, and circulating the mixed gas to the kiln head of the rotary kiln for pre-reducing the iron ore powder in the rotary kiln.
Compared with the prior art, the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the embodiment can directly adopt fine ores as iron ore raw materials, saves raw material pretreatment processes such as sintering, pelletizing and the like, and has the advantages of low capital investment and short construction period; the smelting speed is high, the production efficiency is high, and the production cost is low; the heat energy and the chemical energy of the coal gas are completely recycled; high automation degree and less pollutant discharge.
In particular, the technical core of the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method is to control the gas-based direct reduction of iron ore powder in a rotary kiln and the final reduction and slag-iron separation of pre-reduced furnace burden in a total oxygen molten pool smelting furnace, ensure that the iron ore powder has higher reduction degree in the rotary kiln and the iron oxide is completely reduced and the slag-iron is separated in the total oxygen molten pool smelting furnace, can produce molten iron for steel making with the same quality as that of blast furnace molten iron under the conditions of no need of iron ore powder agglomeration and no coke consumption, because the rotary kiln gas-based reduction and the total-oxygen molten pool smelting furnace are connected into a whole, the raw materials are pre-reduced in the rotary kiln and then directly hot-charged into the total-oxygen molten pool smelting furnace, the temperature of the pre-reduced materials entering the total-oxygen molten pool smelting furnace can reach 700-1000 ℃, the reduction degree is 40-95%, and the energy consumption required by final reduction and slag-iron separation in the material total-oxygen molten pool smelting furnace can be greatly reduced. Meanwhile, in the iron-making device, the reducing coal gas of the rotary kiln is the smelting furnace coal gas generated by the total-oxygen molten pool smelting furnace and the kiln tail coal gas of the rotary kiln, wherein the smelting furnace coal gas comprises CO + H in percentage by volume2 70～80％、CO220-30% of kiln tail gas, and the volume percentage of the kiln tail gas is CO + H2 45～55％、CO225-35%, and the balance being dust, wherein Fe can be realized by utilizing CO in smelting furnace gas and kiln tail gas2O3And FeO, and can also reduce the tail gas emission of the ironmaking device.
However, because the temperature of the top gas of the total-oxygen molten pool smelting furnace is high (about 1500 ℃), and the temperature of the top gas directly introduced into the rotary kiln is too high, the furnace burden of the rotary kiln can be melted or formed, the temperature of the gas mixed by the top gas and the tail gas of the rotary kiln is reduced to the proper temperature (700-1000 ℃) for the gas-based reduction of the iron ore powder by utilizing the recycling cooling of the tail gas of the rotary kiln, and then the top gas is introduced into the rotary kiln from the kiln head.
In addition, because the reduction of the iron oxide and the coal gas in the rotary kiln is an exothermic reaction, the rotary kiln does not need to be heated externally, and the high-efficiency reduction in the rotary kiln can be realized only by controlling the temperature of the coal gas entering the rotary kiln within the range of 700-1000 ℃.
It should be noted that, in order to further improve the utilization rate of the kiln tail gas and the smelting furnace gas and the reduction rate of the iron ore powder in the rotary kiln, the temperature of the kiln tail gas can be controlled within the range of 600-800 ℃, the temperature of the smelting furnace gas can be controlled within the range of 1300-1600 ℃, and the temperature of the mixed gas can be controlled within the range of 700-1000 ℃.
In order to improve the mixing uniformity of smelting raw materials, in the step 1, the iron ore powder and the flux can be premixed according to a designed proportion, and the mixture is added into the rotary kiln after being uniformly mixed, so that the mixing uniformity of the raw materials can be improved, and the reduction rate of the iron ore powder in the rotary kiln is further improved.
In step 2, the oxygen may be pure oxygen or oxygen-enriched gas, for example, the oxygen concentration is 80% to 100%, and the oxygen-enriched gas refers to air with a volume fraction of oxygen greater than the average volume fraction of oxygen in air, that is, the volume fraction of oxygen in the oxygen-enriched gas is greater than 21%. Wherein, the pure oxygen gas is blown in to improve the combustion rate of the coal powder at the tuyere and reduce the heat taken away by the coal gas of the total oxygen molten pool smelting furnace, but the pure oxygen gas has high price. Although the cost of blowing the oxygen-enriched gas is low, the inert gas nitrogen can take away a large amount of heat, and the energy utilization efficiency is reduced.
Considering that the reduction rate of the iron ore powder in the rotary kiln is affected by the dust in the kiln tail gas, in the step 2, the kiln tail gas can be dedusted by a deduster (for example, a bag deduster) and then mixed with the generated smelting furnace gas, so that the deduster can effectively remove the dust in the kiln tail gas of the rotary kiln, reduce the influence of the dust on the reduction rate of the iron ore powder, and improve the reduction rate of the iron ore powder.
It should be noted that the temperature of the kiln tail gas of the rotary kiln is within the range of 600-800 ℃, so as to avoid the high-temperature kiln tail gas damaging the dust remover and affecting the dust removal effect, before the kiln tail gas is subjected to dust removal, a heat exchanger can be adopted to exchange heat with the kiln tail gas, so that the temperature of the kiln tail gas is reduced to the proper temperature (below 200 ℃) for dust removal of the dust remover.
In order to fully utilize the dust of the mobile phone in the dust remover, the dust in the kiln tail gas collected by the dust remover is pneumatically conveyed and sprayed into the total-oxygen molten pool smelting furnace through the spray gun, so that the high-efficiency utilization of iron powder ore is realized. As the coal gas in the rotary kiln is easy to bring the fine ores into the dust remover, in order to improve the utilization efficiency of the fine ores, the dust collected by the dust remover is sprayed into the total-oxygen molten pool smelting furnace through a spray gun.
Likewise, consider CO in kiln tail gas2The reduction rate of the iron ore powder in the rotary kiln can be influenced, so the kiln tail gas after dust removal can be CO2After removal, the CO is mixed with the generated smelting furnace gas2The remover can effectively remove CO in the kiln tail gas of the rotary kiln2Reduction of CO2Influence on the reduction rate of the iron ore powder, thereby improving the reduction rate of the iron ore powder. In addition, since the suitable temperature for dust removal by the dust remover is 200 ℃ or lower, CO2The proper temperature of the remover is below 60 ℃, and the dust remover can absorb part of heat in the dust removing process to further reduce the temperature of the kiln tail gas after dust removal, so that the kiln tail gas can sequentially exchange heat, remove dust and remove CO from the kiln tail gas from the viewpoint of energy conservation2Then mixing with the generated smelting furnace gas.
Notably, via CO2Removing CO by a remover2Then, the temperature of the kiln tail gas can be reduced to below 60 ℃, if the kiln tail gas is completely and directly added into the smelting furnace gas of the total oxygen molten pool smelting furnace, the temperature of the mixed gas of the kiln tail gas and the smelting furnace gas is too low to be controlled within the range of 700-1000 ℃, and if the CO is removed, the temperature of the mixed gas is too low2The rear kiln tail gas part is added into the smelting furnace gas of the total oxygen molten pool smelting furnace, the whole circulation of the kiln tail gas can not be realized, therefore, the kiln tail gas before dust removal is used for heating and removing CO2The temperature of the kiln tail gas can reach 400-500 ℃, and the kiln tail gas can be completely recycled on the basis of ensuring that the temperature of the mixed gas is in the range of 700-1000 DEG CAnd the reduction efficiency of the rotary kiln is improved. Simultaneously, kiln tail gas and CO are separated from the kiln tail gas before dust removal by utilizing a heat exchanger2The heat exchange of the kiln tail gas can realize the high-efficiency utilization of the waste heat of the kiln tail gas, and no additional afterburning equipment is needed.
In order to avoid the excessive reduction of the temperature of the furnace burden after the pre-reduction of the rotary kiln and influence the reduction rate of the furnace burden entering the total oxygen molten pool smelting furnace, the mixed gas can exchange heat with the pre-reduced furnace burden discharged from the kiln head of the rotary kiln in the process of introducing into the kiln head of the rotary kiln, so that the temperature of the furnace burden after the pre-reduction of the rotary kiln is further improved, the excessive reduction of the temperature of the furnace burden after the pre-reduction of the rotary kiln is avoided, and the reduction rate of the furnace burden in the total oxygen molten pool.
Example two
The embodiment provides a rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making device, which comprises a raw material bin, a rotary kiln 3, a total oxygen molten pool smelting furnace 5, a pulverized coal bin 6, an oxygen tank 9, a slag tank 8 and a hot metal tank 7, and is shown in the figures 1 to 4. Wherein, the raw material bin, the rotary kiln 3 and the total oxygen molten pool smelting furnace 5 are sequentially connected, a slag iron outlet of the total oxygen molten pool smelting furnace 5 is respectively connected with a slag tank 8 and a hot metal tank 7, and a discharge hole of the coal powder bin 6 and an air outlet of the oxygen tank 9 are both communicated with an air inlet of the total oxygen molten pool smelting furnace 5; the gas outlet (positioned at the kiln tail) of the rotary kiln 3 is communicated with the gas inlet (positioned at the kiln head) of the rotary kiln 3, and the gas outlet of the total oxygen molten pool smelting furnace 5 is communicated with the gas inlet at the kiln head of the rotary kiln 3.
When the method is implemented, smelting raw materials are added into the rotary kiln 3 through a raw material bin according to a certain proportion, iron ore powder is directly reduced in the rotary kiln 3 through heating and gas-based reduction, the reduced furnace burden is directly hot-charged into the total oxygen molten pool smelting furnace 5, and coal powder in the coal powder bin 6 and oxygen in the oxygen tank 9 are blown into the total oxygen molten pool smelting furnace 5 through a tuyere. Coal gas at the tail of the rotary kiln 3 is mixed with smelting furnace coal gas generated by a total oxygen molten pool smelting furnace 5 and enters the head of the rotary kiln 3, and iron ore powder is reduced in the rotary kiln 3. The iron ore powder is pre-reduced and then enters a total oxygen molten pool smelting furnace 5 for final reduction and slag iron separation.
The main reaction is as follows: fe2O3+CO(g)＝2FeO+CO2(g)、FeO+CO(g)＝Fe+CO2(g)。
It should be noted that when no kiln tail gas and high temperature gas are generated, i.e. at the initial stage of operation of the equipment, a mixed gas of pulverized coal and oxygen may be injected into the total oxygen molten pool smelting furnace 5, and the pulverized coal is combusted to obtain CO, which is introduced into the rotary kiln 3 as the reducing atmosphere at the initial stage of operation of the equipment.
Compared with the prior art, the beneficial effects of the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making device provided by the embodiment are basically the same as the beneficial effects of the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method provided by the embodiment one, and detailed descriptions are omitted here.
It should be noted that, in general, the raw materials used for iron making mainly include iron ore powder and flux, and therefore, the raw material bin may include an iron ore powder bin 1, a flux bin 2 and a mixing bin 13, discharge ports of the iron ore powder bin 1 and the flux bin 2 are connected to a feed port of the mixing bin 13, and a discharge port of the mixing bin 13 is connected to a feed port of the rotary kiln 3. When the method is implemented, the iron ore powder can be transferred into the iron ore powder bin 1, the flux is loaded into the flux bin 2, when the iron ore powder needs to be fed, the discharge ports of the iron ore powder bin 1 and the flux bin 2 are opened, and the iron ore powder and the flux enter the mixing bin 13 in proportion for premixing, so that the mixing uniformity of raw materials is improved, and the reduction rate of the iron ore powder in the rotary kiln 3 is improved.
Considering that the dust in the kiln tail gas influences the reduction rate of the iron ore powder in the rotary kiln 3, the gas outlet of the rotary kiln 3 can be connected with the gas inlet of the rotary kiln 3 through a dust remover 11 (for example, a bag-type dust remover), and the dust remover 11 can effectively remove the dust in the kiln tail gas of the rotary kiln 3, reduce the influence of the dust on the reduction rate of the iron ore powder, and thus improve the reduction rate of the iron ore powder.
It should be noted that the temperature of the kiln tail gas of the rotary kiln 3 is within the range of 600-800 ℃, so as to avoid the high-temperature kiln tail gas from damaging the dust remover 11 and affecting the dust removal effect, the gas outlet of the rotary kiln 3 can be connected with the dust remover 11 through the heat exchanger 10, so that the temperature of the kiln tail gas is reduced to the proper temperature (below 200 ℃) for dust removal of the dust remover 11.
In order to fully utilize the dust of the mobile phone in the dust remover 11, the dust outlet of the dust remover 11 can be connected with the total oxygen molten pool smelting furnace 5, and the dust collected by the dust remover 11 is pneumatically conveyed and sprayed into the total oxygen molten pool smelting furnace 5 through a spray gun, so that the high-efficiency utilization of iron powder ore is realized. As the coal gas in the rotary kiln 3 is easy to bring the fine ores into the dust remover 11, in order to improve the utilization efficiency of the fine ores, the dust collected by the dust remover 11 is sprayed into the total oxygen molten pool smelting furnace 5 through a spray gun.
Likewise, consider CO in kiln tail gas2Also affects the reduction rate of the iron ore powder in the rotary kiln 3, so that the gas outlet of the rotary kiln 3 can pass through CO2The remover 12 is connected with the air inlet of the rotary kiln 3, and CO2The remover 12 can effectively remove CO in the tail gas of the rotary kiln 32Reduction of CO2Influence on the reduction rate of the iron ore powder, thereby improving the reduction rate of the iron ore powder.
It is noted that the temperature of kiln tail gas of the rotary kiln 3 is within the range of 600-1000 ℃, and CO is2The suitable temperature of the remover 12 is below 60 ℃, and the air outlet of the rotary kiln 3 can also pass through the heat exchanger 10 and CO2The remover 12 is connected to reduce the temperature of the kiln tail gas to CO2A suitable temperature for remover 12 (below 60 c).
Of course, the iron-making apparatus may be provided with the dust collector 11 and the CO at the same time2The remover 12, notably, CO, is suitably cooled to 200 ℃ or lower in the dust collector 112The suitable temperature of the remover 12 is below 60 ℃, and the temperature of the kiln tail gas after dust removal is further reduced because the dust remover 11 absorbs part of the heat in the dust removal process, therefore, the gas outlet of the rotary kiln 3 can sequentially pass through the heat exchanger 10, the dust remover 11 and the CO from the viewpoint of energy conservation2The remover 12 is connected to the air inlet of the rotary kiln 3.
Notably, via CO2Remover 12 removes CO2Then, the temperature of the kiln tail gas can be reduced to below 60 ℃, if the kiln tail gas is completely and directly added into the smelting furnace gas of the total oxygen molten pool smelting furnace 5, the temperature of the mixed gas of the kiln tail gas and the smelting furnace gas is too low to be controlled within the range of 700-1000 ℃, and if the CO is removed, the temperature of the mixed gas is too low2The part of the kiln tail gas is added into a total oxygen molten poolIn the furnace gas of the furnace 5, the whole circulation of the furnace tail gas cannot be realized, and therefore, CO2The remover 12 can be connected with the air inlet of the rotary kiln 3 through a heat exchanger 10, and the kiln tail gas before dust removal is used for heating and removing CO2The temperature of the kiln tail gas can reach 400-500 ℃, on the basis of ensuring that the temperature of the mixed gas is within the range of 700-1000 ℃, the kiln tail gas is completely recycled, and the reduction efficiency of the rotary kiln 3 is improved. Meanwhile, kiln tail gas before dust removal and CO removal are carried out by utilizing the heat exchanger 102The heat exchange of the kiln tail gas can realize the high-efficiency utilization of the waste heat of the kiln tail gas, and no additional afterburning equipment is needed.
In order to realize the temperature adjustment of the mixed gas of the kiln tail gas and the smelting furnace gas, a kiln tail gas flow valve 14 can be arranged on a connecting pipeline between the gas outlet of the rotary kiln 3 and the gas inlet of the rotary kiln 3, a smelting furnace gas flow valve 15 can be arranged on a connecting pipeline between the total oxygen molten pool smelting furnace 5 and the gas inlet of the rotary kiln 3, the flow rates of the kiln tail gas and the smelting furnace gas entering the rotary kiln 3 can be respectively controlled through the two flow valves, and the temperature of the mixed gas of the kiln tail gas and the smelting furnace gas can be accurately controlled.
It should be noted that, because the kiln tail gas flow valve 14 and the smelting furnace gas flow valve 15 are arranged, the kiln tail gas and the smelting furnace gas may not be completely recycled, so the kiln tail gas discharge port may be formed in the rotary kiln 3, the smelting furnace gas discharge port may be formed in the oxy-fuel molten pool smelting furnace 5, and both may be connected to other power generation devices or gas user pipelines.
Illustratively, the heat required by the total-oxygen molten pool smelting furnace 5 is mainly provided by injecting oxygen gas into the oxygen combustion pulverized coal bunker 6 from an oxygen tank 9, wherein the oxygen gas in the oxygen tank 9 can be pure oxygen gas or oxygen-enriched gas, and the oxygen-enriched gas refers to air with the volume fraction of oxygen being larger than the average volume fraction of oxygen in the air, namely, the volume fraction of oxygen in the oxygen-enriched gas is larger than 21%. Wherein, the pure oxygen gas is blown in to improve the combustion rate of the coal powder at the tuyere and reduce the heat taken away by the smelting furnace gas of the total oxygen molten pool smelting furnace 5, but the pure oxygen gas has high price. Although the cost of blowing the oxygen-enriched gas is low, the inert gas nitrogen can take away a large amount of heat, and the energy utilization efficiency is reduced.
In order to avoid that the temperature of the furnace burden after the pre-reduction of the rotary kiln 3 is reduced too much and the reduction rate of the furnace burden entering the full-oxygen molten pool smelting furnace 5 is influenced, the gas outlet of the full-oxygen molten pool smelting furnace 5 can be connected with the gas inlet of the rotary kiln 3 through the discharging pipe 4, that is, the discharging port and the gas inlet of the rotary kiln 3 are the same port, and the feeding port and the gas outlet of the full-oxygen molten pool smelting furnace 5 are the same port, so that the smelting furnace gas (more than 1500 ℃) of the full-oxygen molten pool smelting furnace 5 can exchange heat with the furnace burden after the pre-reduction in the discharging pipe 4, the temperature of the furnace burden after the pre-reduction is further improved, and the temperature of the furnace burden after the pre-reduction of the rotary.
As for the structure of the rotary kiln 3, specifically, it may include an inner liner 18 (for example, a heat-resistant steel inner liner 18), insulating bricks 17, an outer shell 16 (for example, a steel shell), and a plurality of shoveling plates 19 provided on the inner wall of the inner liner 18, which are sequentially nested from inside to outside. Wherein, the fixed end of the shoveling plate 19 is fixedly connected with the lining 18, and the suspended end of the shoveling plate 19 is provided with a bending part 20 facing the rotation direction of the rotary kiln 3; the free end of the shoveling plate 19 is inclined to the rotation direction of the rotary kiln 3 with respect to the radial direction of the lining 18. When the method is implemented, the iron ore powder is added from the tail of the rotary kiln 3, the shoveling plates 19 fixed on the inner wall of the kiln shovel the iron ore powder in the rotating process of the rotary kiln 3, the iron ore powder falls down after being raised to a certain height, and the fallen iron ore powder is fully basic with the reducing atmosphere and is reduced by the reducing atmosphere. Because the rotary kiln 3 has a certain inclination angle, the iron ore powder gradually moves from the tail of the kiln to the head of the kiln in the process of repeatedly shoveling and falling, thereby realizing the deep reduction of the fine ore. The rotary kiln 3 is provided with a shoveling plate 19, a bent part 20 facing the rotation direction of the rotary kiln 3 is arranged at the suspended end of the shoveling plate 19, and the bent part 20 can ensure that the iron ore powder is raised to a certain height, so that the reduction time of the iron ore powder is ensured; meanwhile, in the rotation process of the rotary kiln 3, the iron ore powder is repeatedly raised and reduced, so that higher reduction rate and metallization rate are achieved. Meanwhile, in the rotary kiln 3, the suspended end of the shoveling plate 19 is inclined towards the rotation direction of the rotary kiln 3 relative to the radial direction of the lining 18, so that the falling iron ore powder can be lifted up by the shoveling plate 19 again.
In order to reduce the deposition of iron ore powder at the junction of the material shoveling plate 19 and the bending portion 20, the junction of the material shoveling plate 19 and the bending portion 20 may be arc-shaped, so that the junction of the material shoveling plate 19 and the bending portion 20 can be prevented from forming corners through the arc-shaped, the stress concentration at the junction of the material shoveling plate 19 and the bending portion 20 can be reduced, and the deposition of iron ore powder at the junction of the material shoveling plate 19 and the bending portion 20 can be reduced.
Similarly, in order to reduce the deposition of iron ore powder at the connection between the shoveling plate 19 and the lining 18, the connection between the shoveling plate 19 and the lining 18 may also be arc-shaped.
In order to promote the raising of the iron ore powder between the shoveling plates 19, the arc shape can be a convex arc shape, and when the iron ore powder falls onto the convex arc shape in the rotation process of the rotary kiln 3, the convex arc shape can enable the iron ore powder to be fully raised at the joint, so that the reduction time and the reduction rate of the iron ore powder are further improved.
As for the shape of the scraper plate 19, specifically, the cross-sectional shape of the scraper plate 19 along the radial direction of the liner 18 may be a straight line or an arc, and likewise, the cross-sectional shape of the bent portion 20 along the radial direction of the liner 18 may also be a straight line or an arc.
In order to increase the reduction rate of the iron ore powder on the basis of ensuring the treatment capacity, the radial included angle α between the shoveling plate 19 and the lining 18 can be controlled to be 10 ° to 45 °, for example, 23 °. This is because the smaller the included angle is, the lower the height of the iron ore powder uplift is, which is not beneficial to the reduction of the iron ore powder, but can improve the treatment capacity; the larger the included angle is, the higher the shoveling height of the iron ore powder is, which is beneficial to the reduction of the iron ore powder, but the treatment capacity is reduced, therefore, the included angle between the shoveling plate 19 and the liner 18 in the radial direction can be controlled at 10-45 degrees, and the reduction rate of the iron ore powder can be improved on the basis of ensuring the treatment capacity.
In order to improve the reduction rate of the iron ore powder on the basis of ensuring the treatment capacity, the distance between the fixed ends of two adjacent shoveling plates 19 is 0.5-0.8 m, illustratively, for the rotary kiln 3 with the diameter of 2-3 m, the number of the shoveling plates 19 can be controlled to be 18-30, the larger the diameter of the rotary kiln 3 is, the more the shoveling plates 19 are arranged, the smaller the rotary kiln 3 is, and the less the shoveling plates 19 are arranged. This is because the distance between the fixed ends of two adjacent shoveling plates 19 is too small, which can increase the shoveling amount too much, and the speed of the iron ore powder moving from the kiln tail to the kiln head is too small, which will affect the treatment amount; the distance between the fixed ends of two adjacent shoveling plates 19 is too large, so that the shoveling amount is too small, the reduction of the iron ore powder is not facilitated, and the reduction rate of the iron ore powder is influenced.
In order to avoid the poor-fluidity iron ore powder from being retained between the two adjacent shoveling plates 19, the length D of each shoveling plate is 1/8-1/4 of the diameter of the rotary kiln 3, and it should be noted that for the good-fluidity iron ore powder, the length D of each shoveling plate can be larger, which is beneficial to raising the iron ore powder, and for the poor-fluidity iron ore powder, the length D of each shoveling plate is smaller, so that the poor-fluidity iron ore powder can be prevented from being retained between the two adjacent shoveling plates 19, the ratio of the length D of each shoveling plate to the diameter of the rotary kiln 3 is limited within the above range, which not only can promote the reduction of the iron ore powder, but also can prevent the poor-fluidity iron ore powder from being.
In order to balance the reduction of the iron ore powder and the movement rate of the iron ore powder, the width L of the shoveling plate can be controlled to be 0.2-0.6 m, so that the iron ore powder can move towards the direction of a kiln head, and the treatment capacity is ensured. It should be noted that the width L of the shoveling plate may be determined according to the length of the rotary kiln 3, and the larger the length of the rotary kiln 3 is, the larger the width L of the shoveling plate is, the smaller the length of the rotary kiln 3 is, and the smaller the width L of the shoveling plate is.
For the length D of the bent portion, it may be 10% to 30% of the length D of the shoveling plate, and it is noted that the total length of the shoveling plate 19 and the bent portion 20 needs to be controlled within a certain range, so the length D of the bent portion with the larger length D of the shoveling plate is smaller, and the length D of the bent portion with the smaller length D of the shoveling plate is larger.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (3)
1. A rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method is characterized by comprising the following steps:
step 1: adding iron ore powder and a flux into a rotary kiln according to a designed proportion, and directly reducing the iron ore powder in the rotary kiln by heating and gas-based reduction to generate kiln tail gas to obtain pre-reduced furnace burden;
step 2: the pre-reduction furnace charge is directly hot-charged into an oxy-fuel bath smelting furnace, mixed gas of coal powder and oxygen is sprayed into the oxy-fuel bath smelting furnace, the pre-reduction furnace charge is stirred, final reduction and slag-iron separation are carried out, smelting furnace gas is generated, and slag and molten iron are obtained; mixing the generated kiln tail gas with the smelting furnace gas to obtain mixed gas, and circulating the mixed gas to the kiln head of the rotary kiln for pre-reducing iron ore powder in the rotary kiln;
the iron-making method realizes Fe by using CO in smelting furnace gas and kiln tail gas2O3And reduction of FeO;
the device adopted by the rotary kiln gas-based reduction-total oxygen molten pool smelting iron-making method comprises a raw material bin, a rotary kiln, a total oxygen molten pool smelting furnace, a coal dust bin, an oxygen tank, a slag tank and a hot metal ladle, wherein the raw material bin, the rotary kiln and the total oxygen molten pool smelting furnace are sequentially connected, a slag iron outlet of the total oxygen molten pool smelting furnace is respectively connected with the slag tank and the hot metal ladle, and a discharge hole of the coal dust bin and an air outlet of the oxygen tank are both communicated with an air inlet of the total oxygen molten pool smelting furnace; the gas outlet of the rotary kiln is communicated with the gas inlet of the rotary kiln, and the gas outlet of the total oxygen molten pool smelting furnace is communicated with the gas inlet of the kiln head of the rotary kiln;
the rotary kiln comprises a lining, insulating bricks, a shell and a plurality of shoveling plates arranged on the inner wall of the lining, wherein the lining, the insulating bricks and the shell are sequentially sleeved from inside to outside; the suspended end of the shoveling plate deflects towards the rotation direction of the rotary kiln relative to the radial direction of the lining;
the raw material bin comprises an iron ore powder bin, a flux bin and a mixing bin, discharge ports of the iron ore powder bin and the flux bin are connected with a feed port of the mixing bin, and a discharge port of the mixing bin is connected with a feed port of the rotary kiln; in the step 1, the iron ore powder and the flux are premixed according to a design proportion, and are added into the rotary kiln after being uniformly mixed;
in the step 2, the kiln tail gas is dedusted by a deduster and then mixed with the generated smelting furnace gas;
before the kiln tail gas is dedusted, heat exchange is carried out between the kiln tail gas and a heat exchanger, so that the temperature of the kiln tail gas is reduced to the temperature required by dedusting of a deduster;
removing CO from kiln tail gas after dust removal2Then mixing the obtained product with the produced smelting furnace gas;
heating kiln tail gas before dust removal to remove CO2The kiln tail gas after the reaction is used for removing CO2Raising the temperature of the kiln tail gas to 400-500 ℃;
and dust in the kiln tail gas collected by the dust remover is sprayed into the total-oxygen molten pool smelting furnace.
2. The rotary kiln gas-based reduction-total oxygen bath smelting iron-making method as claimed in claim 1, wherein in the step 2, the oxygen is pure oxygen gas or oxygen-enriched gas.
3. The rotary kiln gas-based reduction-total oxygen bath smelting iron-making method as claimed in claim 1 or 2, characterized in that the mixed gas exchanges heat with pre-reduction charge discharged from the kiln head of the rotary kiln in the process of introducing into the kiln head of the rotary kiln, so that the temperature of the pre-reduction charge is raised.
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