CN115652009A - System and method for preparing sponge iron - Google Patents
System and method for preparing sponge iron Download PDFInfo
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- CN115652009A CN115652009A CN202211172423.2A CN202211172423A CN115652009A CN 115652009 A CN115652009 A CN 115652009A CN 202211172423 A CN202211172423 A CN 202211172423A CN 115652009 A CN115652009 A CN 115652009A
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- iron
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- bed reactor
- sponge iron
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 273
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 127
- 238000000034 method Methods 0.000 title claims abstract description 58
- 239000000463 material Substances 0.000 claims abstract description 67
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 59
- 239000003546 flue gas Substances 0.000 claims abstract description 59
- 239000007789 gas Substances 0.000 claims abstract description 47
- 239000000428 dust Substances 0.000 claims abstract description 45
- 238000006722 reduction reaction Methods 0.000 claims abstract description 37
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 23
- 239000003245 coal Substances 0.000 claims abstract description 21
- 230000008569 process Effects 0.000 claims abstract description 20
- 238000001816 cooling Methods 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 18
- 230000003647 oxidation Effects 0.000 claims abstract description 16
- 238000003860 storage Methods 0.000 claims abstract description 15
- 239000000203 mixture Substances 0.000 claims abstract description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 32
- 229910052717 sulfur Inorganic materials 0.000 claims description 28
- 239000011593 sulfur Substances 0.000 claims description 27
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical group [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 9
- 239000011701 zinc Substances 0.000 claims description 9
- 229910052725 zinc Inorganic materials 0.000 claims description 9
- 238000006477 desulfuration reaction Methods 0.000 claims description 8
- 230000023556 desulfurization Effects 0.000 claims description 8
- 229910052683 pyrite Inorganic materials 0.000 claims description 8
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 claims description 8
- 239000011028 pyrite Substances 0.000 claims description 8
- 239000002910 solid waste Substances 0.000 claims description 7
- 239000005864 Sulphur Substances 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 5
- 239000012141 concentrate Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 239000002893 slag Substances 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 230000003009 desulfurizing effect Effects 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 239000000779 smoke Substances 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 2
- 230000009467 reduction Effects 0.000 abstract description 20
- 239000002994 raw material Substances 0.000 abstract description 19
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 239000000047 product Substances 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 13
- 238000002485 combustion reaction Methods 0.000 description 12
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 239000002699 waste material Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000002245 particle Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003034 coal gas Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
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- 238000010438 heat treatment Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
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- 238000001179 sorption measurement Methods 0.000 description 2
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- 239000002351 wastewater Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 238000004131 Bayer process Methods 0.000 description 1
- 239000004484 Briquette Substances 0.000 description 1
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical class [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
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- -1 and generally Chemical compound 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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- 238000004043 dyeing Methods 0.000 description 1
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Abstract
The invention discloses a system and a method for preparing sponge iron. The system comprises a mixing device, a storage bin, a fluidized bed reactor, a high-temperature dust collector and a cooling device which are sequentially connected; the fluidized bed reactor comprises a material inlet and a flue gas outlet at the upper part, a return port and a combustion-supporting gas inlet at the lower part, and a temperature control device is arranged in the fluidized bed reactor; the high-temperature dust collector is provided with a dust removal flue gas discharge port connected with the return port. Mixing the iron-containing material with coal, feeding the mixture into a fluidized bed reactor, carrying out oxidation reaction with combustion-supporting gas fed from the lower part, and carrying out reduction reaction based on reducing gas generated by oxidation and released heat; collecting dust from the iron-containing flue gas, and cooling to obtain sponge iron; returning part of the flue gas after dust collection to the fluidized bed reactor for reuse. The invention has low requirement on raw materials, good adaptability, high heat utilization rate, reduced energy consumption, shortened process and reduced production cost, and the oxidation and the reduction are realized in the same fluidized bed reactor.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a system and a method for preparing sponge iron.
Background
Sponge iron is also called direct reduction iron, and generally, iron in iron ore is reduced below a melting temperature by using an oxidation-reduction reaction principle, and the reduced iron is in the form of fine iron cores like sponge, so that the sponge iron is called sponge iron. The sponge iron has a metallization rate of more than 92 percent, normally contains more than 90 percent of iron, contains 0.2 percent of carbon, contains few other elements such As S, P, sn, sb, as and the like, has uniform granularity and pure components, is an ideal raw material for electric furnace steelmaking, can improve the comprehensive toughness and plasticity of steel, reduce cold brittleness and the like, and has become a trend for the electric furnace steelmaking development of iron and steel enterprises by replacing part of special high-quality steel smelted by scrap steel. In addition, the sponge iron is also a novel water treatment material, has the characteristics of large specific surface area, high activity and the like, and has stronger electrochemical adsorption, oxidation reduction, physical adsorption and coagulating sedimentation capabilities due to the increase of the specific surface area, so that the sponge iron is more and more emphasized in water treatment, such as the deoxidization of boiler water, the treatment of electroplating wastewater, the treatment of organic printing and dyeing wastewater and the like.
The existing production processes of sponge iron are various, such as a rotary kiln method, a shaft furnace method, a shaft tank method, a belt machine method and the like, most of the processes are carried out by mixing, drying, preheating, reducing and the like on solids, the whole treatment process flow is long, equipment is huge, the investment cost is high, the trial run time is long, the production rate is lower than that of gas reduction, and the energy consumption is high.
Among them, the rotary kiln method and the shaft furnace method are widely used. For example:
1) The one-step rotary kiln production process of the reduced iron hot briquetting comprises the following steps: natural gas or coal gas is used as a heat source, CO or anthracite is used as a reducing agent, and a batching and ball pressing system, a drying and heating system, a secondary combustion system, a rotary kiln reduction system, a hot-press forming passivation system, a tail gas exhaust purification system, a coal injection system, a circulating water cooling system and the like are required to be arranged. The main technological process is that iron powder, iron scale and adhesive are mixed in certain proportion, and the mixture is pressed in a ball press to form iron powder balls, which are stoved and heated in a chain plate type stoving machine by the hot blast from a rotary kiln for sintering in the rotary kiln, the sintered balls are sealed and heated in a rotary reduction kiln for reduction and sieving, and the hot reduced balls on the sieve are hot pressed and passivated in a briquetting machine to obtain hot pressed reduced iron briquette product.
2) The Chinese application CN 1042993998A discloses a method and a system for preparing sponge iron by a gas-based shaft furnace, and the technology mainly comprises the step of introducing reducing gas into the shaft furnace to reduce pellets to produce sponge iron.
3) The chinese application CN 111321264A discloses a preparation method of sponge iron, which adopts a tunnel kiln process and comprises the following steps: preparing raw materials, preparing a reducing agent, loading a cylindrical mold, reducing in a tunnel kiln, and cooling products.
4) Chinese application CN1818081A discloses a sponge iron production method, which combines the characteristics of a shaft furnace and a tunnel kiln.
However, the above-mentioned conventional process for producing sponge iron has many problems, although it is improved to some extent. The gas-based shaft furnace method mainly comprises the steps of preparing coal gas from reduced coal for heating and reduction, namely, the requirements on raw materials are high, and the roasting air quantity, the reduction temperature, the air flow distribution and the like need to be fully controlled. The coal-based method is mainly a rotary kiln or a tunnel kiln, and generally comprises the steps of premixing solid fuel/reducing agent and iron ore raw materials and then roasting; the rotary kiln has high control requirements, and if the control is not good, the problems of ring formation and the like can be caused by local overheating in the kiln; in addition, the requirement for the coal types as reducing agents and fuels is high, and the coal types with low ash content, low sulfur content, good reactivity, high fixed carbon, proper amount of volatile components and good ash reflow property are generally selected, so that the operation cost is increased; the tunnel kiln has the problems of low unit yield, large occupied area, high labor intensity, low degree of mechanization, high operation cost and the like.
In summary, the existing process for preparing sponge iron generally has the problems of high raw material requirement, poor adaptability, high energy consumption, long process, complex operation, low mechanization degree and the like.
Disclosure of Invention
According to one embodiment of the invention, the purpose is to provide a system and a method for preparing sponge iron, which can reduce the requirement of raw materials, shorten the flow, improve the utilization rate of energy and reduce the energy consumption. The above object can be achieved by the following technical solution:
according to an aspect of an embodiment of the present invention, there is provided a system for preparing sponge iron, including:
the mixing device is used for mixing the iron-containing material and the coal and sending the mixed material to the storage bin;
the outlet of the storage bin is connected with a screw feeder, and the mixed material stored in the storage bin is fed into the fluidized bed reactor through the screw feeder;
the fluidized bed reactor comprises a material inlet, a combustion-supporting gas inlet, a flue gas outlet and a return port, and a temperature control device is arranged in the fluidized bed reactor; the material inlet and the flue gas outlet are positioned at the upper part, the combustion-supporting gas inlet is positioned at the lower part, so that the entering mixed material and combustion-supporting gas entering from the lower part are subjected to oxidation reaction in the fluidized bed reactor, reduction reaction is carried out in the fluidized bed reactor based on reducing gas generated by oxidation and released heat, and reduced iron is discharged from the flue gas outlet along with the flue gas;
a high temperature dust collector, comprising: the inlet, the dedusting flue gas discharge port and the product discharge port are connected with the flue gas outlet, and the dedusting flue gas discharge port is connected with the return port;
and the cooling device is connected with the product discharge port and is used for cooling the discharged product to obtain the sponge iron.
Optionally, the method further comprises: and the desulfurizing device is connected with the dedusting smoke outlet.
Optionally, the desulfurization device is a sulfur preparation device, and sulfur resources in the dedusted flue gas are recovered to prepare a sulfur product.
Optionally, the method further comprises: and the granulating device is arranged in front of the mixing device and is used for granulating the iron-containing material.
Optionally, the method further comprises: and the separation forming device is connected with the cooling device and is used for separating the sponge iron and briquetting the sponge iron.
According to another aspect of the embodiments of the present invention, there is provided a method for preparing sponge iron, including:
mixing iron-containing materials with coal to obtain mixed materials, and conveying the mixed materials to a storage bin;
feeding the mixed material in the storage bin into a fluidized bed reactor by adopting a screw feeder, introducing combustion-supporting gas from the lower part of the fluidized bed reactor, carrying out oxidation reaction on the mixed material and the combustion-supporting gas in the fluidized bed reactor, carrying out reduction reaction in the fluidized bed reactor based on reducing gas generated by oxidation and released heat, and allowing reduced iron to enter a high-temperature dust collector along with flue gas for dust collection; wherein, the temperature in the fluidized bed reactor is controlled to be 900-1200 ℃;
cooling the product after dust collection to obtain sponge iron; returning part of the flue gas after dust collection to the fluidized bed reactor for recycling; and discharging the other part of the flue gas after dust collection.
Optionally, the iron-containing material is iron ore concentrate, scrap steel or bulk solid waste, wherein the bulk solid waste comprises one or more of iron-containing red mud, blast furnace zinc-containing steel ash and pyrite-making acid iron slag.
Optionally, if the iron-containing material contains sulfur, before another part of the flue gas after dust collection is discharged outside, the method further includes: and carrying out desulfurization treatment on the other part of flue gas after dust collection.
Optionally, the step of performing desulfurization treatment on the other part of flue gas after dust collection includes: judging the sulfur concentration of the other part of the flue gas after dust collection; if the concentration is higher than the preset value, recovering sulfur resources, and preparing a sulfur product by using the sulfur resources; if the concentration is not higher than the preset value, adopting a abandoning method to carry out desulfurization treatment.
Optionally, before mixing the iron-containing material with the coal, the method further comprises: granulating the iron-containing material; after the step of obtaining the sponge iron, the method further comprises the following steps: and sorting the sponge iron and briquetting.
Optionally, the method further comprises: determining the feeding amount and the introduction amount of air or oxygen according to the composition of the iron-containing material so as to ensure the required heat and reducing gas amount of the reducing atmosphere; wherein the determination is made by model calculation.
Has the advantages that: the invention is based on a fluidized bed reactor, and the oxidation combustion and the reduction reaction are realized in the same reactor, namely the fluidized bed reactor. The mixed material and the combustion-supporting gas are subjected to oxidation (combustion) reaction in the fluidized bed reactor to generate reducing gas and release heat, and the reducing gas generated by combustion and the released heat are subjected to reduction reaction in the fluidized bed reactor, namely, the heat energy generated by oxidation combustion and the reducing gas are directly utilized for reduction reaction, so that the heat utilization rate is improved, the energy consumption is reduced, the flow is greatly shortened, and the preparation cost of the sponge iron is reduced. Iron obtained by reaction in the fluidized bed reactor enters a high-temperature dust collector along with flue gas, the dust is collected, and then the sponge iron is obtained by cooling, and meanwhile, part of the flue gas after dust collection returns to the fluidized bed reactor to recycle heat and reducing gas carried by the flue gas, so that the energy utilization rate is further improved.
The method has low requirements on raw materials, can treat iron-containing materials such as iron ore concentrate, waste steel and the like, is particularly suitable for treating bulk solid wastes such as iron-containing red mud, zinc-containing steel ash of a blast furnace, iron slag of acid production from pyrite and the like, and has low requirements on the quality of coal; the method has better adaptability, and different post-treatment processes can be combined according to the composition of the iron-containing material; the method has the advantages of high product quality, less impurities, low operation cost, simple operation, high mechanization degree and the like.
Drawings
FIG. 1 is a schematic structural diagram of a system for preparing sponge iron according to an embodiment of the present invention.
FIG. 2 is a schematic flow chart of a method for preparing sponge iron according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Fig. 1 schematically shows the structure of a system for preparing sponge iron in one embodiment of the present invention. As shown in fig. 1, the system for preparing sponge iron provided in this embodiment includes a mixing device 1, a storage bin 2, a fluidized bed reactor 3, a high temperature dust collector 4, a cooling device 5, and a sorting and forming device 6, which are connected in sequence. Wherein the outlet of the storage bin 2 is also connected with a screw feeder (not shown). The fluidized bed reactor 3 comprises a material inlet and a flue gas outlet which are positioned at the upper part, a return port and a combustion-supporting gas inlet which is positioned at the bottom part, and a temperature control device (not shown) is arranged inside the fluidized bed reactor 3. The high-temperature dust collector 4 comprises an inlet connected with the flue gas outlet, a dedusting flue gas discharge port and a product discharge port, and the dedusting flue gas discharge port is connected with the return port.
Fig. 2 schematically shows a flow of a method for preparing sponge iron in one embodiment of the present invention. The method for preparing sponge iron according to the present invention will be further described with reference to FIGS. 1 and 2. Specifically, the following steps may be included:
and S10, mixing the iron-containing material and the coal to obtain a mixed material, and conveying the mixed material to a storage bin.
Wherein the iron-containing materials can be iron ore concentrate and waste steel, and can also be bulk solid wastes such as iron-containing red mud, zinc-containing steel ash of a blast furnace, acid iron slag produced by pyrite and the like. Coal is used as fuel and reducing agent, and has no other quality requirement.
In addition, if the particle size of the iron-containing material does not meet the requirement, the iron-containing material is granulated before mixing, for example, a pellet preparation device or a crushing device can be arranged, so that the particle size of the iron-containing material meets the feeding requirement, for example, the particle size of the iron-containing material is controlled within the range of 2 mm-10 mm through granulation, so that the contact area of the iron-containing material such as iron oxide and reducing gas is further increased, and the subsequent reduction reaction efficiency is improved.
And S20, feeding the mixed material in the storage bin into a fluidized bed reactor by using a screw feeder, introducing combustion-supporting gas from the lower part of the fluidized bed reactor, carrying out oxidation reaction on the mixed material and the combustion-supporting gas introduced from the bottom in the fluidized bed reactor, and carrying out reduction reaction on the basis of reducing gas generated by oxidation and released heat. Wherein, the combustion-supporting gas can be oxygen, air and the like. Furthermore, the temperature in the fluidized bed reactor is controlled to be 900-1200 ℃ to ensure that the reduction reaction is effectively and fully carried out.
Taking an oxide taking iron-containing materials as iron as an example, the main chemical reactions in the fluidized bed reactor comprise:
C+O 2 →CO 2
C+1/2O 2 →CO
C+CO 2 →2CO
C+H 2 O→CO+H 2
CO+H 2 O→CO 2 +H 2
CO+Fe 2 O 3 →CO 2 +Fe
H 2 +Fe 2 O 3 →H 2 O+Fe。
the mixed material of iron-containing material and coal is fed into fluidized bed reactor, and makes them produce oxidation reaction with combustion-supporting gas coming from bottom of fluidized bed reactor, and the coal and air coming from bottom are combusted to release heat, and then the CO and H can be produced in the upper portion of reactor 2 And (3) waiting for the reducing gas and releasing heat, wherein the released heat is used as a heat source of a reduction reaction, the reduction reaction is carried out in a reducing atmosphere formed by the reducing gas, the iron-containing oxide is reduced into iron, and the reduced iron powder leaves the fluidized bed reactor along with the flue gas and enters a high-temperature dust collector for dust collection.
The combustion-supporting gas inlet is arranged at the bottom, so that the oxidation combustion reaction mainly occurs in the lower area of the fluidized bed reactor, the heat and the reducing gas generated by the oxidation combustion enter the upper area, the reduction reaction mainly occurs in the upper area of the fluidized bed reactor, and the flue gas generated by the reduction in the upper area directly leaves the fluidized bed reactor from the upper flue gas outlet; the oxidation and the reduction are carried out in the same reactor, and in the gas-solid reaction process, the materials are fully contacted with the gas, so that the reaction efficiency is improved, and the utilization rate of the raw materials is improved.
In addition, the combustion of coal is exothermic reaction, and the reduction needs heat absorption, the heat required by the reduction reaction is released from the combustion of coal, and the combustion and the reduction are carried out in the same reactor, and the inventor of the application further finds that if the air adding amount is small, the combustion of coal is low in heat release, and the reduction cannot be satisfied; if the amount of air added is too large, H will be caused 2 And the reduction of the amount of CO, the reducing atmosphere in the upper part of the fluidized bed reactor cannot be effectively controlled, and thus the reduction cannot be efficiently performed. In order to more efficiently perform oxidation and reduction in the same reactor, the feeding amount of the mixed material is determined according to the composition of the iron-containing material, and the feeding amount of combustion-supporting gas such as air is controlled to ensure the required heat of the reducing atmosphere and the reducing atmosphere at the upper part of the fluidized bed reactor. Preferably, based on the chemical reaction in the fluidized bed reactor, the proportional relation between the feeding amount of the well-mixed material and the air is determined through model calculation so as to achieve the optimal effect.
Furthermore, when iron-bearing material contains iron sulphides, i.e. the material contains elemental sulphur, then in the oxidation zone the sulphur in the material forms SO 2 Further to the upper part, SO 2 The reducing gas is reduced by the reducing gas, and part of the reducing gas required by the reduced iron reaction is consumed, so that in the case that the reduction of the iron is finished, the content of sulfur element in the mixed material needs to be considered to determine the feeding amount and the feeding amount of combustion-supporting gas so as to ensure the high-efficiency operation of the iron reduction reaction.
Step S30, feeding the reacted flue gas into a high-temperature dust collector for dust collection; cooling the product after dust collection to obtain sponge iron; returning part of the flue gas after dust collection to the fluidized bed reactor; and discharging the other part of the flue gas after dust collection.
In order to avoid the heat loss of the flue gas, part of the flue gas subjected to high-temperature dust removal is used as a heat source and returned to the fluidized bed reactor for heat reutilization; in addition, the reducing gas carried in the part of the flue gas can be reused, so that the energy consumption is greatly reduced.
In addition, after cooling, other dust exists in the sponge iron, and can be separated in a magnetic separation mode and the like, so that subsequent application is facilitated. For example, the cooled sponge iron is further sorted, and briquetted after sorting for use, for example, sent to a steel mill for use as a raw material.
In addition, before the other part of the residual flue gas in the high-temperature dust collector after dust collection is discharged, corresponding treatment modes can be adopted for flue gas treatment and the like according to the condition of raw materials (iron-containing materials), such as whether other pollutants are contained. For example, when sulfur is contained, desulfurization treatment is required, specifically, if the sulfur concentration in the flue gas is high (higher than a preset value), a process for preparing sulfur from flue gas is adopted, and sulfur resources such as H in the flue gas are recovered 2 S/COS, producing a sulfur product; if the sulfur concentration in the flue gas is low (not higher than a preset value), treatment modes such as a disposal method desulfurization process and the like can be adopted, so that the flue gas is discharged up to the standard. The preset value of the sulfur concentration is not particularly limited, and can be set according to the regulations in the field.
In addition, the product after high-temperature dust collection can be returned to the fluidized bed reactor, so that the unreduced materials in the product can participate in the reaction again, the reaction efficiency is further improved, the method can be realized under the condition that other devices are not added to the system and other reactors are not added, the investment is reduced, and the recovery rate is improved.
In one embodiment, pyrite is used as the feedstock (i.e., iron-containing material). The main elements in the pyrite are iron and sulfur, the system is adopted and the steps are carried out, namely, sponge iron can be directly produced through material mixing, feeding reaction, dust collection and cooling, and sulfur is prepared by recycling sulfur resources. At present, pyrite is usually oxidized and roasted by a fluidized bed roaster, and the produced iron powder is supplied to a steel mill to prepare sulfuric acid by using sulfur entering flue gas. Compared with the process, the invention has the advantages that the pyrite is treated, the process energy consumption is reduced, the sponge iron and the sulfur are obtained, and the product value is higher.
In one embodiment, the zinc-containing steel ash of the blast furnace is used as a raw material. The main elements in the zinc-containing steel ash of the blast furnace are iron and zinc, the system is adopted and the process is carried out through the steps, namely, sponge iron can be directly produced through mixing, feeding reaction, dust collection and cooling, and zinc oxide is directly produced through zinc oxide smoke dust recovery. At present, a rotary hearth furnace is mostly adopted for treatment, the produced iron powder is supplied to a steel mill, and the iron powder is difficult to recover when the content of zinc element is high. Compared with the process, the process has wider raw material adaptability, and can recover zinc oxide besides iron.
In one embodiment, iron-containing red mud is used as a raw material. Iron-containing red mud is a byproduct of an alumina plant, and because raw material components and an alumina production process are different, chemical components and mineral compositions of the red mud are greatly different, taking red mud produced by a certain Bayer process as an example, main elements are iron (accounting for about 40 percent) and Al 2 O 3 (about 17%) and SiO 2 (about 9%) using the above system and through the above steps, sponge iron was directly produced. Wherein the reduction temperature is controlled at 1150 ℃.
Some embodiments of the invention also have the following advantages over the prior art:
1) The process route has low requirement on raw materials, better adaptability, wider coal source and lower cost. Especially for front-end raw materials, the method has less restriction conditions, and can treat not only iron ore concentrate or waste steel but also large solid wastes such as iron-containing red mud, zinc-containing steel ash of a blast furnace, iron slag of acid production from pyrite and the like.
2) Short process flow, simple operation, high mechanization degree, high quality of produced products and less impurities.
3) The reactor is a gas-solid reactor in the form of a fluidized bed, and oxidation (combustion heat release) and reduction reactions are realized in the same reactor, so that the system is simplified, and the energy consumption is reduced. And (3) multi-stage reduction is not needed, and if the reduction degree is required to be improved, the product can be returned to the fluidized bed reactor to participate in the reaction again.
4) Various resources in the raw materials are recycled in a classified manner, and waste is turned into wealth. The flue gas treatment can be carried out according to different raw materials, and other valuable metals or other products can be recovered while the sponge iron is produced by adopting a corresponding post-treatment process.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (11)
1. A system for producing sponge iron, comprising:
the mixing device is used for mixing the iron-containing material and the coal and sending the mixed material to the storage bin;
the outlet of the storage bin is connected with a screw feeder, and the mixed material stored in the storage bin is fed into the fluidized bed reactor through the screw feeder;
the fluidized bed reactor comprises a material inlet, a combustion-supporting gas inlet, a flue gas outlet and a return port, and a temperature control device is arranged in the fluidized bed reactor; the material inlet and the flue gas outlet are positioned at the upper part, the combustion-supporting gas inlet is positioned at the lower part, so that the entering mixed material and combustion-supporting gas entering from the lower part are subjected to oxidation reaction in the fluidized bed reactor, reduction reaction is carried out in the fluidized bed reactor based on reducing gas generated by oxidation and released heat, and reduced iron is discharged from the flue gas outlet along with the flue gas;
a high temperature dust collector, comprising: the inlet, the dedusting flue gas discharge port and the product discharge port are connected with the flue gas outlet, and the dedusting flue gas discharge port is connected with the return port;
and the cooling device is connected with the product discharge port and is used for cooling the discharged product to obtain the sponge iron.
2. The system for producing sponge iron as claimed in claim 1 further comprising: and the desulfurizing device is connected with the dedusting smoke outlet.
3. The system for preparing sponge iron as claimed in claim 2, wherein the desulphurization device is a sulphur preparation device, and sulphur products are prepared by recovering sulphur resources in the dedusted flue gas.
4. The system for producing sponge iron as claimed in claim 1 further comprising:
the granulating device is arranged in front of the mixing device and is used for granulating the iron-containing material;
and the separation forming device is connected with the cooling device and is used for separating the sponge iron and briquetting the sponge iron.
5. A process for producing sponge iron, comprising:
mixing iron-containing materials with coal to obtain mixed materials, and conveying the mixed materials to a storage bin;
feeding the mixed material in the storage bin into a fluidized bed reactor by adopting a screw feeder, introducing combustion-supporting gas from the lower part of the fluidized bed reactor, carrying out oxidation reaction on the mixed material and the combustion-supporting gas in the fluidized bed reactor, carrying out reduction reaction in the fluidized bed reactor based on reducing gas generated by oxidation and released heat, and feeding reduced iron into a high-temperature dust collector along with flue gas for dust collection; wherein the temperature in the fluidized bed reactor is controlled to be 900-1200 ℃;
cooling the product after dust collection to obtain sponge iron; returning part of the flue gas after dust collection to the fluidized bed reactor for recycling; and discharging the other part of the flue gas after dust collection.
6. The method for preparing sponge iron as claimed in claim 5 wherein the iron bearing material is iron concentrate, steel scrap or bulk solid waste, wherein the bulk solid waste comprises one or more of iron bearing red mud, blast furnace zinc bearing steel ash, pyrite making acid iron slag.
7. The method for preparing the sponge iron as claimed in claim 5, wherein if the iron-bearing material contains sulfur, before another part of the flue gas after dust collection is discharged, the method further comprises: and carrying out desulfurization treatment on the other part of flue gas after dust collection.
8. The method for preparing the sponge iron as claimed in claim 7, wherein the step of desulfurizing the other part of the flue gas after dust collection comprises the following steps:
judging the sulfur concentration of the other part of the flue gas after dust collection;
if the concentration is higher than the preset value, recovering sulfur resources, and preparing a sulfur product by using the sulfur resources;
if the concentration is not higher than the preset value, adopting a discarding method to carry out desulfurization treatment.
9. The method for preparing sponge iron as claimed in claim 5 further comprising, prior to blending the iron bearing material with coal: granulating the iron-containing material.
10. The process for producing sponge iron as claimed in claim 5 further comprising, after the step of obtaining sponge iron: and sorting the sponge iron and briquetting.
11. The process for producing sponge iron as claimed in claim 5 further comprising: according to the composition of the iron-containing material, the feeding amount and the introduction amount of air or oxygen are determined so as to ensure the required heat and reducing gas amount of the reducing atmosphere.
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