Method for reducing emission of CO flue gas in iron ore sintering process

Abstract

The invention discloses a method for reducing emission of CO flue gas in an iron ore sintering process. The emission reduction method for the CO flue gas in the iron ore sintering process comprises the following steps that iron-containing materials are fully mixed; modifying part of the fuel to obtain modified fuel; mixing the fully mixed iron-containing material, the fully mixed modified fuel, the remaining unmodified fuel and a flux, and granulating to obtain a mixture; and putting the mixture into a sintering cup, and carrying out ignition sintering, crushing and cooling to obtain the finished product sintered ore. The invention provides a method for reducing emission of CO flue gas in the iron ore sintering process, which can effectively reduce the average concentration of CO in the flue gas and the CO emission per ton of sintered ore, improve the yield of the sintered ore and the strength of a rotary drum and reduce solid fuel consumption.

Description

Technical Field

[0001] The invention relates to the technical field of ironmaking, and in particular to a method for reducing CO flue gas emissions during an iron ore sintering process. Background Art

[0002] my country's annual sinter production exceeds 1.2 billion tons. Sinter production is the largest energy consumer and flue gas pollution emission link in the steel industry, accounting for nearly 40% of the pollution load of the steel industry. Sintering flue gas contains a variety of solid and gaseous pollutants, which is also the focus and difficulty of emission reduction in the steel industry. As the government attaches importance to environmental protection, multiple departments of the State Council jointly promote ultra-low emission transformation of steel enterprises. X 、NO X At present, most sintering plants have actively adopted source reduction, process control and terminal treatment technologies to reduce pollutant generation and emissions, and have achieved remarkable results. As the extreme climate problems caused by the greenhouse effect become more and more serious, the reduction of carbon oxides in iron ore sintering has become more and more important.

[0003] The production of carbon oxides during the sintering process mainly comes from the combustion of solid fuels, and the flue gas produced contains 7% to 15% CO2 and 0.4% to 2% CO. A lot of research has been done on CO2 emission reduction in iron ore sintering, but not much research has been done on CO emission reduction. CO, as a colorless, odorless, tasteless pollutant that is not easily detected by human senses, usually causes chronic poisoning. After being inhaled by the human body with air, it combines with hemoglobin in the human body, reducing the chance of oxygen and hemoglobin, and damaging the human heart and nervous system. The harm of CO to the human body has gradually attracted attention. The air quality index AQI issued in 2012 lists carbon monoxide together with fine particulate matter, inhalable particulate matter, sulfur dioxide, nitrogen dioxide, ozone, etc. as the main pollutants involved in air quality evaluation. In January 2018, the Environmental Protection Tax Law began to include CO emissions from waste gas in the taxable objects. In 2019, the Ministry of Ecology and Environment, the National Development and Reform Commission, the Ministry of Industry and Information Technology, the Ministry of Finance, and the Ministry of Transport jointly issued the Opinions on Promoting the Implementation of Ultra-low Emissions in the Steel Industry, which put forward stricter requirements for CO emissions in steel production. Therefore, research on the reduction of CO emissions from iron ore sintering process is of great significance to the green, low-carbon and sustainable development of the steel industry. Summary of the invention

[0004] In order to solve the above-mentioned technical problem of CO emission reduction in iron ore sintering, which has been less studied, the present invention provides a method for reducing CO flue gas in the iron ore sintering process. By modifying the fuel, the average CO concentration in the flue gas and the CO emission per ton of sintered ore can be effectively reduced, which is beneficial to improving the sintered ore yield and drum strength and reducing solid fuel consumption.

[0005] The present invention provides a method for reducing CO flue gas emissions during iron ore sintering, comprising the following steps:

[0006] Take an appropriate amount of iron-containing material and mix the iron-containing material thoroughly;

[0007] Taking a proper amount of fuel, and modifying part of the fuel to obtain modified fuel;

[0008] The fully mixed iron-containing material, the modified fuel, the remaining unmodified fuel and an appropriate amount of flux are mixed and granulated to obtain a sintering mixture;

[0009] The sintering mixture is placed in a sintering cup, and after ignition, sintering, crushing and cooling, a finished sintered ore is obtained.

[0010] In a preferred embodiment of the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention, the iron-containing material is concentrate, powder ore or a mixture of the two.

[0011] In a preferred embodiment of the method for reducing CO flue gas emissions in an iron ore sintering process provided by the present invention, the flux is at least one of limestone, dolomite and quicklime.

[0012] In a preferred embodiment of the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention, the modified fuel is prepared by taking appropriate amounts of coke powder, quicklime and water, first mixing the quicklime and water in equal proportions to convert them into lime milk, and then mixing part of the coke powder with the lime milk to obtain the modified fuel.

[0013] In a preferred embodiment of the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention, the coke powder used for modification accounts for 80% to 100% of the total mass of the coke powder.

[0014] In a preferred embodiment of the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention, the mass ratio of the coke powder used for modification to the lime milk is 1.5 to 3:1.

[0015] In a preferred embodiment of the method for reducing CO flue gas emissions in an iron ore sintering process provided by the present invention, before the coke powder is mixed with the lime milk, the coke powder is subjected to fuel classification, and the fuel classification is based on 1 mm as the boundary, and the coke powder is divided into coarse-grained coke powder of +1 mm and fine-grained coke powder of -1 mm.

[0016] In a preferred embodiment of the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention, appropriate amounts of coke powder, quicklime and water are respectively taken, and the coke powder is subjected to fuel classification, wherein the fuel classification is based on 1 mm as the boundary, and the coke powder is divided into coarse-grained coke powder of +1 mm and fine-grained coke powder of -1 mm; then the quicklime and the water are mixed in equal proportions and converted into lime milk, and then the coarse-grained coke powder in the coke powder is mixed with the lime milk to obtain modified coarse-grained fuel; finally, the fully mixed iron-containing material, the modified coarse-grained fuel, the fine-grained coke powder in the coke powder and the flux are mixed and granulated to obtain a mixture.

[0017] Compared with the prior art, the method for reducing CO flue gas emissions during iron ore sintering provided by the present invention has the following beneficial effects:

[0018] 1. Improve the fuel storage state in the mixture

[0019] According to the sintering method provided by the present invention, quicklime is added to water to form lime milk, which is then mixed with coke powder in a certain proportion. After the quicklime becomes lime milk, it will absorb fine particles of coke powder, and the average particle size of the granulated mixture will be significantly increased, and the air permeability index of the material layer will be significantly improved. At the same time, the Ca element contained in the lime milk can catalyze the combustion of coke powder particles and improve the combustion efficiency.

[0020] 2. Improve the quality of sintered ore

[0021] By adopting the sintering method provided by the present invention, the binding phase of the obtained finished sintered ore is mainly calcium ferrite, which improves the fuel occurrence state in the mixture, increases the permeability of the material layer, is conducive to the formation of the calcium ferrite binding phase, optimizes sintering mineralization, increases the sintered ore yield and drum strength, and reduces solid fuel consumption.

[0022] 3. Improve the degree and efficiency of fuel combustion during sintering and reduce CO emissions

[0023] By adopting the sintering method provided by the present invention, after the fuel is modified, the fuel occurrence state is optimized, the fuel combustion efficiency and the degree of complete combustion are greatly improved, and the average concentration of CO in the flue gas is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0025] Figure 1 The present invention provides a process flow chart of a method for reducing CO flue gas emissions during iron ore sintering. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] In this embodiment, the specific raw material ratio is shown in Table 1, wherein the iron-containing material is a mixture of powder ore and concentrate (Brazil, Chile, Harbin powder, Yangdi, Newman, oxidized iron sheet, desulfurized steel slag, magnetic separation powder), the flux is a mixture of quicklime, limestone and dolomite, and the fuel is coke powder.

[0029] Table 1 Sintering raw material ratio table

[0030]

[0031] Fixed sintering basic parameters: sintering basicity 2.0, return ore external mixing 10%, granulation time 5min, mixed material moisture 7.0%, material height 900mm, ignition temperature 1100℃, ignition time 2min, ignition negative pressure -5KPa, sintering negative pressure -12KPa, insulation system: >950℃, insulation time 1min.

[0032] See also Figure 1 , Figure 1 The present invention provides a process flow chart of a method for reducing CO flue gas emissions during iron ore sintering.

[0033] The method for reducing CO flue gas emission in the iron ore sintering process comprises the following steps:

[0034] (1) taking an appropriate amount of iron-containing material and thoroughly mixing the iron-containing material;

[0035] (2) taking an appropriate amount of fuel and modifying the fuel to obtain a modified fuel;

[0036] Specifically, the preparation method of the modified fuel is: respectively taking appropriate amounts of coke powder, quicklime and water, first mixing the quicklime and the water in equal proportions to convert them into lime milk, and then mixing the coke powder and the lime milk in a mass ratio of 2:1 to obtain the modified fuel;

[0037] (3) mixing and granulating the fully mixed iron-containing material, the modified fuel and an appropriate amount of flux to obtain a mixture;

[0038] (4) The mixed material is placed in a sintering cup, and after ignition, sintering, crushing and cooling, a finished sintered ore is obtained, and the sintering flue gas data is recorded.

[0039] In this embodiment, the yield rate, drum strength, solid fuel consumption, average CO concentration, and CO emission per ton of sintered ore obtained are 70.01%, 58.33%, 50.13 kg / t, 6281.18 ppm, and 23.8 kg, respectively.

[0040] Example 2

[0041] The basic content of this embodiment is the same as that of Embodiment 1, except that the coke powder and the lime milk are mixed at a mass ratio of 1.5:1 to obtain the modified fuel.

[0042] In this embodiment, the yield rate, drum strength, solid fuel consumption, average CO concentration, and CO emission per ton of sintered ore obtained are 66.79%, 58.80%, 50.39 kg / t, 7283.1 ppm, and 24.85 kg, respectively.

[0043] Example 3

[0044] The basic content of this embodiment is the same as that of Embodiment 1, except that the coke powder and the lime milk are mixed at a mass ratio of 3:1 to obtain the modified fuel.

[0045] In this embodiment, the yield rate, drum strength, solid fuel consumption, average CO concentration, and CO emission per ton of sintered ore obtained are 66.92%, 59.10%, 51.39 kg / t, 7199.2 ppm, and 24.29 kg, respectively.

[0046] Example 4

[0047] The basic content of this embodiment is the same as that of Embodiment 1, except that: the coke powder accounting for 80% of the total mass of the coke powder is mixed with the lime milk in a mass ratio of 2:1 to obtain a modified fuel, and the fully mixed iron-containing material, the modified fuel, the remaining coke powder accounting for 20% of the total mass of the coke powder and the flux are mixed and granulated to obtain a mixture.

[0048] In this embodiment, the yield rate, drum strength, solid fuel consumption, average CO concentration, and CO emission per ton of sintered ore obtained are 68.92%, 58.10%, 50.45 kg / t, 6979.3 ppm, and 23.89 kg, respectively.

[0049] Example 5

[0050] The basic content of this embodiment is the same as that of Embodiment 1, except that: the preparation method of the modified fuel is as follows: respectively taking appropriate amounts of coke powder, quicklime and water, firstly subjecting the coke powder to fuel classification, wherein the fuel classification is based on 1 mm as the boundary, and the coke powder is divided into coarse-grained coke powder of +1 mm and fine-grained coke powder of -1 mm; then the quicklime and the water are mixed in equal proportions and converted into lime milk, and then the coarse-grained coke powder in the coke powder is mixed with the lime milk to obtain modified coarse-grained fuel; finally, the fully mixed iron-containing material, the modified coarse-grained fuel, the fine-grained coke powder in the coke powder and the flux are mixed and granulated to obtain a mixture.

[0051] In this embodiment, the yield rate, drum strength, solid fuel consumption, average CO concentration, and CO emission per ton of sintered ore obtained are 67.21%, 61.60%, 51.22kg / t, 6365.5ppm, and 24.01kg, respectively.

[0052] Comparative Example 1

[0053] The basic content of this embodiment is the same as that of Embodiment 1, except that: the fuel is not modified, and the iron-containing material, the fuel and an appropriate amount of flux are subjected to conventional mixing, granulation, distribution and ignition sintering. The yield, drum strength, solid fuel consumption, average CO concentration and CO emissions per ton of sintered ore are 66.48%, 61.33%, 53.28 kg / t, 7777.8 ppm and 28.96 kg respectively.

[0054] By comparing the data of Example 1, Example 2, Example 3, Example 4, Example 5 and Comparative Example 1, it can be found that by modifying the fuel, the average CO concentration in the flue gas and the CO emissions per ton of sintered ore can be effectively reduced, the sintered ore yield and drum strength can be improved, and the solid fuel consumption can be reduced.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for reducing CO flue gas emissions during iron ore sintering, characterized in that: The following steps are involved: Take an appropriate amount of iron-containing material and mix the iron-containing material thoroughly; Taking a proper amount of fuel, and modifying part of the fuel to obtain modified fuel; The fully mixed iron-containing material, the modified fuel, the remaining unmodified fuel and an appropriate amount of flux are mixed and granulated to obtain a sintering mixture; The sintering mixture is placed in a sintering cup, and after ignition, sintering, crushing and cooling, a finished sintered ore is obtained.

2. The method for reducing CO flue gas emissions during iron ore sintering according to claim 1, characterized in that: The iron-containing material is concentrate, powder ore or a mixture of the two.

3. The method for reducing CO flue gas emissions during iron ore sintering according to claim 1, characterized in that: The flux is at least one of limestone, dolomite and quicklime.

4. The method for reducing CO flue gas emissions during iron ore sintering process according to any one of claims 1 to 3, characterized in that: The preparation method of the modified fuel is: take appropriate amounts of coke powder, quicklime and water, first mix the quicklime and the water in equal proportions to convert them into lime milk, and then mix part of the coke powder with the lime milk to obtain the modified fuel.

5. The method for reducing CO flue gas emissions during iron ore sintering process according to claim 4, characterized in that: The coke powder used for modification accounts for 80% to 100% of the total mass of the coke powder.

6. The method for reducing CO flue gas emissions during iron ore sintering process according to claim 5, characterized in that: The mass ratio of the coke powder used for modification to the lime milk is 1.5 to 3:

1.

7. The method for reducing CO flue gas emissions during iron ore sintering process according to claim 5 or 6, characterized in that: Before the coke powder is mixed with the lime milk, the coke powder is subjected to fuel classification. The fuel classification is to classify the coke powder into coarse-grained coke powder of +1 mm and fine-grained coke powder of -1 mm with a boundary of 1 mm.

8. The method for reducing CO flue gas emissions during iron ore sintering process according to claim 7, characterized in that: Firstly, appropriate amounts of coke powder, quicklime and water are taken respectively, and the coke powder is subjected to fuel classification, wherein the fuel classification is based on 1 mm as the boundary, and the coke powder is divided into coarse-grained coke powder of +1 mm and fine-grained coke powder of -1 mm; then the quicklime and the water are mixed in equal proportions to convert into lime milk, and then the coarse-grained coke powder in the coke powder is mixed with the lime milk to obtain modified coarse-grained fuel; finally, the fully mixed iron-containing material, the modified coarse-grained fuel, the fine-grained coke powder in the coke powder and the flux are mixed and granulated to obtain a mixture.

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