CN115341063B - Efficient reduction method for iron ore - Google Patents
Efficient reduction method for iron ore Download PDFInfo
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- CN115341063B CN115341063B CN202110521717.0A CN202110521717A CN115341063B CN 115341063 B CN115341063 B CN 115341063B CN 202110521717 A CN202110521717 A CN 202110521717A CN 115341063 B CN115341063 B CN 115341063B
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 152
- 238000000034 method Methods 0.000 title claims abstract description 117
- 230000009467 reduction Effects 0.000 title claims abstract description 95
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 69
- 239000000843 powder Substances 0.000 claims abstract description 79
- 230000008569 process Effects 0.000 claims abstract description 70
- 238000005243 fluidization Methods 0.000 claims abstract description 42
- 238000002485 combustion reaction Methods 0.000 claims abstract description 21
- 238000000227 grinding Methods 0.000 claims abstract description 19
- 238000011946 reduction process Methods 0.000 claims abstract description 18
- 238000013007 heat curing Methods 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 40
- 239000011362 coarse particle Substances 0.000 claims description 22
- 238000012216 screening Methods 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 17
- 238000000926 separation method Methods 0.000 claims description 14
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 13
- 239000011707 mineral Substances 0.000 claims description 13
- 238000001723 curing Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 10
- 238000003825 pressing Methods 0.000 claims description 9
- 239000011230 binding agent Substances 0.000 claims description 7
- 239000010419 fine particle Substances 0.000 claims description 7
- QJZYHAIUNVAGQP-UHFFFAOYSA-N 3-nitrobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid Chemical compound C1C2C=CC1C(C(=O)O)C2(C(O)=O)[N+]([O-])=O QJZYHAIUNVAGQP-UHFFFAOYSA-N 0.000 claims description 3
- 239000002028 Biomass Substances 0.000 claims description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
- 239000004115 Sodium Silicate Substances 0.000 claims description 3
- 229920002472 Starch Polymers 0.000 claims description 3
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 3
- 239000000440 bentonite Substances 0.000 claims description 3
- 229910000278 bentonite Inorganic materials 0.000 claims description 3
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 3
- 239000004568 cement Substances 0.000 claims description 3
- 239000004021 humic acid Substances 0.000 claims description 3
- 239000004571 lime Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- 235000019422 polyvinyl alcohol Nutrition 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 3
- 239000008107 starch Substances 0.000 claims description 3
- 235000019698 starch Nutrition 0.000 claims description 3
- 239000004480 active ingredient Substances 0.000 claims description 2
- 239000012141 concentrate Substances 0.000 claims description 2
- 238000006722 reduction reaction Methods 0.000 abstract description 92
- 230000008901 benefit Effects 0.000 abstract description 7
- 239000002994 raw material Substances 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 239000000126 substance Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 58
- 238000001465 metallisation Methods 0.000 description 11
- 238000003723 Smelting Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 239000008188 pellet Substances 0.000 description 5
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000036962 time dependent Effects 0.000 description 3
- 230000005587 bubbling Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 229910001608 iron mineral Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000000629 steam reforming Methods 0.000 description 1
- 238000001029 thermal curing Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0033—In fluidised bed furnaces or apparatus containing a dispersion of the material
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Dispersion Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention belongs to the fields of chemical industry and metallurgy, and discloses a method for efficiently reducing iron ore. The method strengthens the high-temperature fluidization reduction process of the iron ore powder by grinding, granulating and modifying, prevents the easy-to-adhere ore powder from losing flow, enhances the raw material applicability of fluidization direct reduction, simultaneously improves the reduction reaction rate, improves the energy efficiency of the process and realizes the efficient reduction of the iron ore; the gas utilization rate is improved through the combustion and preheating of the reduction tail gas; the heat is provided for the heat curing process by the hot combustion tail gas through heat exchange between the thermal reduction ore and the reducing gas, so that the energy utilization rate of the system is improved. The method has the advantages of wide raw material adaptability, low energy consumption, environmental friendliness, high resource utilization rate, high energy utilization rate and high reaction efficiency, and has good economic and social benefits.
Description
Technical Field
The invention belongs to the fields of chemical industry and metallurgy, and particularly relates to a method for efficiently reducing iron ore.
Background
In order to get rid of the restriction of coking coal resource shortage on iron ore smelting development, the method is suitable for increasingly higher environmental protection requirements, and non-blast furnace smelting technology, especially direct reduction iron making technology, has become one of the research hotspots of iron ore smelting. The direct reduction method can be classified into a coal-based method and a gas-based method according to the reducing agent. The coal-based reduction mainly uses a rotary kiln and a rotary hearth furnace as reactors, and the gas-based reduction mainly uses a shaft furnace and a fluidized bed. Compared with coal-based reduction, gas-based reduction has the advantages of high energy efficiency, small pollution and the like, and accords with the sustainable development concept of green iron making.
The shaft furnace is a commonly used iron ore gas-based direct reduction reactor, and mainly takes lump ore and pellet ore as raw materials due to the structure and operation characteristics, along with the shortage of high-grade high-quality lump ore resources, the preparation of the pellet ore gradually becomes an essential link for smelting the shaft furnace, the preparation process of the pellet ore needs to undergo the steps of pelletizing, green pellet screening, drying and preheating, roasting and solidifying, cooling and screening and the like, the operation is complex, wherein the roasting and solidifying step is usually carried out at about 1250 ℃, and the energy consumption is higher. Compared with a shaft furnace, the fluidized bed omits a pellet ore preparation link, can directly treat the powder ore, has the advantages of high mass transfer and heat transfer efficiency between gas and solid phases, high reduction rate and the like, and is a promising iron ore smelting technology. Typical fluidization direct reduction ironmaking processes exist in the prior art, such as FIOR process, FINMET process, and Circored process.
In the FIOR process, iron ore powder with granularity smaller than 5mm sequentially passes through 4 fluidized bed reactors, the primary fluidized bed preheats the ore powder to 760 ℃, the reduction temperature of the two-to-four-stage fluidized bed reactors is 690-780 ℃, and the pressure is 1.11MPa. The metallization rate of the reduced iron ore powder reaches 92%, and the iron ore powder can be hot-pressed into blocks (US 5082251). The fluidization reducing gas is obtained by reforming natural gas steam, H 2 The content exceeds 90%, and the mixture is mixed with purified circulating gas to enter a four-stage fluidized bed reactor, and then the three-stage fluidized bed reactor and the two-stage fluidized bed reactor are in a gas-solid countercurrent state. Proper amounts of non-stick inert powders such as CaO, mgO and the like are added to prevent the loss of flow during the reduction of the iron ore powder in the FIOR process. In 1973 Mckee company designed a set of plants with 40 ten thousand tons per year in venezuela based on the FIOR method, and built in 1976, the actual annual output in 1998 reached 39 ten thousand tons. For economic reasons, the plant has been shut down around 2000.
FINMET technology was developed by FIOR Venezuela corporation in association with the Oldham Union (VAI) at the end of the 90 s of the 20 th century by modification of the FIOR method, and has been established in Australia and Venezuela. In the FINMET process, iron ore powder with granularity smaller than 12.7mm sequentially passes through 4 fluidized bed reactors connected in series and flows reversely with fluidization reducing gas. The temperature of the primary fluidized bed reactor is about 550 ℃, the temperature of the secondary fluidized bed reactor is about 800 ℃ and the pressure is 1.1-1.4MPa, and the temperature of the secondary fluidized bed reactor is gradually increased downwards. Four-stage fluidized bed outlet productionThe metallization rate of the product reaches 93 percent, and the content of C is about 0.5 to 3 percent (US 5833734). Delivering the reduced iron powder to a hot press, hot-pressing into HBI with density of more than 5g/cm 3 The product is compact, and the oxidation of the product can be reduced. The fluidized reducing gas consists of fresh gas and recycle gas obtained after natural gas steam reforming, and is heated to 850 ℃ before entering the four-stage reactor. In order to avoid the occurrence of lost flow, raw materials used in the FINMET process are mainly coarse ore powder which is not easy to adhere, the content of fine ore powder (the granularity is smaller than 0.1 mm) must be controlled within 20 percent, otherwise inert powder such as CaO, mgO and the like is needed to be added.
The Circored process was developed by Ottotai, germany (Oulotec, original Lurgi Metallurgie, lurgi Metallurgical Co.) based on the gas-based rapid direct reduction technology of iron ore fines (US 5527379, US 5603748). The circumrad reduction system consists of a primary Circulating Fluidized Bed (CFB) and a secondary bubbling Fluidized Bed (FB). The CFB reactor used in the factory with the production capacity of 50 ten thousand tons/year has the outer diameter of 5.2m, the height of 29.6m, the outer diameter of an external circulation cyclone of 5.5m, the outer diameter of the FB reactor of 7.0m, the total length of 17.5m and four material chambers inside. Fluidization of the reducing gas to pure H 2 . The reduction temperature of the primary fast fluidized bed is 630-650 ℃, the reduction temperature of the secondary bubbling fluidized bed is about 680 ℃, and the pressure is 0.4MPa. The obtained reduced iron powder can be hot-pressed into blocks or directly used for powder metallurgy. In order to avoid the occurrence of lost flow in the fluidization reduction process of the iron ore powder, the reduction temperature in the circumored process is controlled below 680 ℃, and the iron ore powder which is not easy to adhere and is about 1mm is selected as the raw material.
In addition, many chinese patents also propose fluidized direct reduction ironmaking processes, such as CN103667571B, CN103725819B, CN106319126B, CN106467930B, etc. For the typical gas-solid non-catalytic reaction of the direct reduction of the iron ore gas base, the dynamic process can be described by an unreacted nuclear model (a shrinking nuclear model), and the relation between the complete conversion time of particles and the particle size under different control steps (external diffusion, internal diffusion and interfacial chemical reaction) in the condensation model can be known, so that the smaller the particles, the shorter the required complete conversion time, namely the faster the reduction reaction rate. From the gas-solid fluidization theory, it is known that the initial fluidization velocity of particles is proportional to the square of the particle size, i.e., the smaller the particles, the less gas is required to maintain the fluidized state. Therefore, in theory, the finer raw mineral powder is more beneficial to fluidization direct reduction, however, the existing fluidization direct reduction ironmaking process is only suitable for treating coarse mineral powder which is not easy to bond, or non-bonding inert powder is needed to be added to prevent the easy-bonding iron mineral powder from losing flow, which can have great influence on fluidization reduction efficiency, and the advantages of fluidization high-efficiency reduction can not be fully exerted. This is mainly because the easily bondable iron ore powder, especially fine ore powder (less than 0.1 mm), is extremely easily bonded to each other during the fluidized reduction at high temperature (above 600 ℃) to form clusters having a large particle size and deposit at the bottom of the fluidized bed, eventually resulting in the loss of flow of the whole bed (Komatina M, gubenau H w. Metalurgija,2004, 10 (204): 309-328). Once the lost flow occurs, the reduction system has to be stopped, which causes great loss to the production and severely restricts the large-scale popularization and application of the fluidized bed direct reduction iron making.
In conclusion, the high-temperature fluidization reduction process of the iron ore powder is strengthened through technological innovation, so that the easily-bonded ore powder is prevented from losing flow, the reduction efficiency is improved, the energy consumption is reduced, the production cost is saved, and the method is an important way for realizing the efficient reduction of the iron ore in China.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a method for efficiently reducing iron ores. The method can realize the efficient reduction of the iron ore, has wide raw material adaptability, is environment-friendly, has high resource utilization rate, energy utilization rate and reaction efficiency, and has good economic and social benefits.
To achieve the purpose, the invention adopts the following technical scheme:
the method for efficiently reducing the iron ore comprises a mixing and grinding process 1, a briquetting process 2, a heat curing process 3, a crushing and screening process 4, a combustion preheating process 5, a fluidization reduction process 6, a heat exchange process 7 and a separation process 8, and specifically comprises the following steps of:
1) In the mixing and grinding process 1, the iron ore powder and/or the fine particles from the crushing and screening process 4 are added with a binder and mixed uniformly, and ground into fine powder;
2) In the briquetting process 2, the fine powder is pressed into blocks to obtain block materials;
3) In the heat curing process 3, the block-shaped material is heated by the hot combustion tail gas from the combustion preheating process 5 to obtain a cured material;
4) In the crushing and screening step 4, the solidified material is crushed and screened to obtain coarse particles meeting the fluidization reduction requirement, and the rest fine particles are returned to the mixing and grinding step 1 for recycling;
5) In the combustion preheating process 5, air is introduced to fully combust the reducing tail gas from the fluidized reduction process 6 and part of hot reducing gas from the heat exchange process 7, coarse particle mineral powder is preheated, preheated ore and hot combustion tail gas are obtained, and the hot combustion tail gas is sent to the heat curing process 3;
6) In the fluidized reduction process 6, the preheated ore is reduced by hot reducing gas from the heat exchange process 7 to obtain hot reduced ore and reduced tail gas, and the reduced tail gas is sent to the combustion preheating process 5;
7) In the heat exchange process 7, heat exchange is carried out between the hot reducing ore and the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidization reduction process 6;
8) In the separation step 8, the cold reduced ore is separated to obtain reduced iron powder and tailings.
In the mixing and grinding step 1, the grain size of the ground powder is controlled to be not more than 0.01mm. The binder is one or a combination of a plurality of sodium silicate, bentonite, cement, biomass, humic acid, lime, starch and polyvinyl alcohol. The addition mass of the binder is 0.5-10% of the mass of the iron ore powder. The iron ore powder is iron ore concentrate.
In the briquetting process 2, the ground powder is formed by pressing, wherein the pressure is 0.2-20MPa.
In the heat curing procedure 3, the curing temperature is 20-300 ℃ and the curing time is 60-600min.
In the crushing and screening process 4, the screening particle size of the coarse grain mineral powder is controlled to be 0.1-5 mm.
In the fluidized reduction process 6, the reduction temperature is 600-800 ℃, the reduction time is 10-90min, and the reduction pressure is 0.1-1MPa.
The heat exchanging engineeringIn the step 7, the reducing gas is gas or reformed gas, H 2 And CO as an active ingredient.
Compared with the prior art, the invention has the following outstanding advantages:
(1) The invention improves the fluidization quality of the easy-to-adhere iron ore powder in high-temperature fluidization reduction through granulation modification, effectively inhibits lost flow and widens the application range of raw materials for fluidization direct reduction;
(2) According to the method, through the grinding pretreatment of the iron ore, the reaction activity of the powder ore is improved, the reduction process is enhanced, the reduction reaction rate is accelerated, and the process energy efficiency is improved;
(3) According to the invention, through heat exchange between the thermal reduction ore and the reducing gas, the waste heat recovery and utilization method for providing heat for the thermal curing process by the thermal combustion tail gas, and the like, the energy utilization rate of the system is improved.
Drawings
FIG. 1 is a flow chart of a method for efficient reduction of iron ore according to the present invention;
FIG. 2 shows the time-dependent change of the metallization rate of raw ore powder and the modified material of the method described in example 2 in high-temperature fluidization reduction;
FIG. 3 shows the time-dependent change of the metallization rate of the raw ore powder and the modified material of the method described in example 3 in high-temperature fluidization reduction;
fig. 4 shows the time-dependent metallization rate of the raw ore powder and the modified material of the method described in example 4 in high-temperature fluidization reduction.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
Example 1
As shown in fig. 1, the method for efficiently reducing the iron ore comprises a mixing and grinding process 1, a briquetting process 2, a heat curing process 3, a crushing and screening process 4, a combustion preheating process 5, a fluidization reduction process 6, a heat exchange process 7 and a separation process 8, and specifically comprises the following steps:
1) In the mixing and grinding process 1, the iron ore powder and/or the fine particles from the crushing and screening process 4 are added with a binder and mixed uniformly, and ground into fine powder;
2) In the briquetting process 2, the ground powder is pressed into blocks to obtain block materials;
3) In the heat curing step 3, the pressed block is heated by the hot combustion exhaust gas from the combustion preheating step 5 to obtain a cured material;
4) In the crushing and screening step 4, the solidified material is crushed and screened to obtain coarse particles meeting the fluidization reduction requirement, and the rest fine particles are returned to the mixing and grinding step 1 for recycling;
5) In the combustion preheating process 5, air is introduced to fully combust the reducing tail gas from the fluidized reduction process 6 and part of hot reducing gas from the heat exchange process 7, coarse particle mineral powder is preheated, preheated ore and hot combustion tail gas are obtained, and the hot combustion tail gas is sent to the heat curing process 3;
6) In the fluidized reduction process 6, the preheated ore is reduced by hot reducing gas from the heat exchange process 7 to obtain hot reduced ore and reduced tail gas, and the reduced tail gas is sent to the combustion preheating process 5;
7) In the heat exchange process 7, heat exchange is carried out between the hot reducing ore and the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidization reduction process 6;
8) In the separation step 8, the cold reduced ore is separated to obtain reduced iron powder and tailings.
Example 2
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 0.5% of cement into iron ore powder (the total iron content is about 55%), mixing and grinding, pressing into blocks under 0.5MPa, and curing for 300min at 20 ℃ to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 800 ℃ for fluidized reduction for 10min, wherein the reduction pressure is 0.1MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings. As shown in figure 2, the metallization rate of the raw mineral powder and the modified material of the method of the invention changes with time in high-temperature fluidization reduction. It can be seen that the raw mineral powder is subjected to fluidization reduction for 1.1min to generate lost flow, and the modified material of the method can be stably subjected to fluidization reduction for 6min to the metallization rate of about 87%. In addition, the fluidization reduction rate of the modified material of the method is obviously higher than that of the raw ore powder.
Example 3
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 5% bentonite into iron ore powder (the total iron content is about 60%), mixing and grinding, pressing into blocks under 0.2MPa, and curing at 300 ℃ for 480min to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 600 ℃ for fluidized reduction for 90min, wherein the reduction pressure is 1MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings. As shown in figure 3, the metallization rate of the raw mineral powder and the modified material of the method of the invention changes with time in high-temperature fluidization reduction. It can be seen that the raw mineral powder is subjected to fluidization reduction for 25min to generate lost flow, and the modified material of the method can be stably subjected to fluidization reduction for 90min to a metallization rate of about 90%. In addition, the fluidization reduction rate of the modified material of the method is obviously higher than that of the raw ore powder.
Example 4
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, 10% biomass (treated by alkali liquor) is added into iron ore powder (the total iron content is about 62%) and fine particles from a crushing and screening process 4, the mixture is mixed and ground, pressed into blocks under 20MPa, and then the blocks are cured for 120 minutes at 150 ℃ to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 700 ℃ for fluidized reduction for 24min, wherein the reduction pressure is 0.5MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings. As shown in figure 4, the metallization rate of the raw mineral powder and the modified material of the method of the invention in high-temperature fluidization reduction changes regularly with time. It can be seen that the raw mineral powder is subjected to fluidization reduction for 5min to generate lost flow, and the modified material of the method can be stably subjected to fluidization reduction for 24min to a metallization rate of about 88%. In addition, the fluidization reduction rate of the modified material of the method is obviously higher than that of the raw ore powder.
Example 5
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 3% polyvinyl alcohol into iron ore powder (the total iron content is about 68%), mixing and grinding, pressing into blocks under 10MPa, and curing at 200 ℃ for 60min to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 780 ℃ for fluidized reduction for 18min, wherein the reduction pressure is 0.2MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings.
Example 6
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 0.5% sodium silicate into iron ore powder (the total iron content is about 65%), mixing and grinding, pressing into blocks under 5MPa, and curing at 220 ℃ for 60min to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 700 ℃ for fluidization reduction for 60min, wherein the reduction pressure is 0.5MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings.
Example 7
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 2% humic acid into iron ore powder (the total iron content is about 57%), mixing and grinding, pressing into blocks under 6MPa, and curing for 600min at 150 ℃ to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 770 ℃ for fluidized reduction for 60min, wherein the reduction pressure is 0.1MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings.
Example 8
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 5% lime into iron ore powder (the total iron content is about 50%), mixing and grinding, pressing into blocks under 4MPa, and curing for 120min at 120 ℃ to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 850 ℃ for fluidized reduction for 48min, wherein the reduction pressure is 0.3MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings.
Example 9
This example employs a method for efficient reduction of iron ore as described in example 1. Firstly, adding 7% starch into iron ore powder (the total iron content is about 70%), mixing and grinding, pressing into blocks under 8MPa, and curing at 110 ℃ for 480min to obtain a cured material. Crushing and screening the solidified material to obtain coarse particles with the diameter of 0.1-5mm, and burning and preheating the coarse particles by reducing tail gas to obtain preheated ore. And (3) placing the preheated ore in reducing gas at 750 ℃ for fluidized reduction for 90min, wherein the reduction pressure is 0.1MPa, and obtaining the thermal reduction ore. The hot reduced ore is subjected to heat exchange and separation to obtain reduced iron powder and tailings.
The percentages in the invention are not illustrated, and are all mass percent.
The method can be realized by the upper and lower limit values of the interval and the interval value of the process parameters (such as temperature, time and the like), and the examples are not necessarily listed here.
The invention may be practiced without these specific details, using any knowledge known in the art.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.
Claims (5)
1. The method for efficiently reducing the iron ore comprises a mixing and grinding process (1), a briquetting process (2), a heat curing process (3), a crushing and screening process (4), a combustion preheating process (5), a fluidization reduction process (6), a heat exchange process (7) and a separation process (8), and specifically comprises the following steps of:
1) In the mixing and grinding process (1), the iron ore powder and/or the fine particles from the crushing and screening process (4) are added with a binder and mixed uniformly, and the mixture is ground into fine powder with the particle size smaller than 0.01 mm; the addition mass of the binder is 0.5-10% of the mass of the iron ore powder;
2) In the briquetting process (2), the fine powder is pressed into blocks to obtain block materials;
3) In the heat curing process (3), the blocky material is heated to 20-300 ℃ through the hot combustion tail gas from the combustion preheating process (5) to obtain a cured material;
4) In the crushing and screening process (4), the solidified material is crushed and screened to obtain coarse particle mineral powder with the particle size of 0.1-5mm, and the rest fine particles are returned to the mixing and grinding process (1) for recycling;
5) In the burning preheating process (5), introducing air to fully burn the reducing tail gas from the fluidization reduction process (6) and part of hot reducing gas from the heat exchange process (7), preheating coarse particle mineral powder to obtain preheated ore and hot burning tail gas, and sending the hot burning tail gas to the heat curing process (3);
6) In the fluidized reduction process (6), the preheated ore is reduced by hot reducing gas from the heat exchange process (7) at 600-800 ℃ to obtain hot reduced ore and reduced tail gas, and the reduced tail gas is sent to the combustion preheating process (5); in the fluidized reduction process (6), the reduction time is 10-90min, and the reduction pressure is 0.1-1MPa;
7) In the heat exchange process (7), heat exchange is carried out between the hot reducing ore and the reducing gas to obtain cold reducing ore and hot reducing gas, and the hot reducing gas is sent to the fluidization reduction process (6);
8) In the separation step (8), the cold reduced ore is separated to obtain reduced iron powder and tailings.
2. The method for efficient reduction of iron ore according to claim 1, wherein the iron ore powder is iron ore concentrate; the binder is one or a combination of a plurality of sodium silicate, bentonite, cement, biomass, humic acid, lime, starch and polyvinyl alcohol.
3. The method for efficient reduction of iron ore according to claim 1 or 2, wherein in the briquetting process (2), the fine powder is formed by pressing, wherein the pressure is 0.2 to 20MPa.
4. The method for efficient reduction of iron ore according to claim 1 or 2, wherein the curing time in the heat curing process (3) is 60 to 600 minutes.
5. The method for efficiently reducing iron ore according to claim 1 or 2, wherein in the heat exchange step (7), the reducing gas is gas or reformed gas, and the gas is H 2 And CO as an active ingredient.
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