An iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions

Abstract

The present invention belongs to the technical field of iron ore sintering, and specifically relates to an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The method includes batching, primary mixing, secondary mixing, distribution, ignition, and sintering steps, wherein low-carbon alcohol is added in the secondary mixing step. The inventor has found through research that adding an appropriate amount of low-carbon alcohol to the secondary mixing can adjust the sintering temperature of the sintering process and extend the sintering time, which can not only improve the reducibility of the sintered ore, but also significantly reduce the emission of nitrogen oxides. Specifically, the ferrous oxide content in the sintered ore can be reduced from 11% to 9.6% compared with the blank test, and the reducibility of the sintered ore is significantly improved; at the same time, compared with the blank test, the total concentrations of nitrogen monoxide and nitrogen oxides in the sintering flue gas are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of iron ore sintering, and in particular relates to an iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions. Background Art

[0002] Iron ore sintering is an important process in steel production. It is a process of sintering raw materials such as iron ore powder, fuel, flux and various return materials into artificial rich ore under certain conditions to provide raw materials for blast furnace ironmaking. Sintered ore is the most important iron-containing charge for blast furnaces, and its reducibility has an important impact on blast furnace operation and consumption. Reducibility refers to the difficulty of oxygen combined with iron in iron ore to be captured by gas reducing agent, that is, the difficulty of indirect reduction. When sintered ore with poor reducibility is loaded into the blast furnace, it will first affect the gas utilization rate of the upper block belt of the blast furnace, resulting in a decrease in indirect reduction and an increase in direct reduction in the upper part of the blast furnace, affecting the fuel ratio and output of the blast furnace. According to data, a 10% change in the direct reduction of the ore entering the furnace affects the blast furnace fuel ratio and output by 10% respectively, which has an important impact on the intensification of the ironmaking production process and the improvement of its efficiency. Therefore, it is hoped that the ore has good reducibility. The reducibility of sintered ore is negatively correlated with the content of ferrous oxide. Therefore, research on improving the reducibility of sintered ore is generally achieved by controlling the content of ferrous oxide.

[0003] The steel industry is a typical high-energy consumption, high-material consumption and high-pollution industry. It is also one of the main sources of air pollution. Pollutants emitted by the steel industry account for 10% of total industrial emissions. Among them, the sintering process has the highest pollution load, with a pollution load of up to 39.04%, and the waste gas emitted accounts for 40% of the total emissions of all processes.

[0004] The sintering process not only provides raw materials for blast furnace production, but also has the function of absorbing various return materials. It is also the main process for flue gas pollutant emissions. Its NOx emissions account for more than 50% of the corresponding pollutant emissions in the entire steel production process, and are accompanied by pollutants such as alkali and heavy metals. With the annual increase in sintered ore production, the environmental problems it brings are becoming increasingly prominent.

[0005] In the prior art, in order to improve the efficiency of the steel industry and reduce pollution, research is generally conducted on the reducibility of sintered ore and the reduction of nitrogen oxide emissions respectively, without organically combining the two. If a method is provided that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions, it will be of great significance to promoting the development of the steel industry. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that there is no relevant technology that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions, thereby providing an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions.

[0007] To this end, the present invention provides the following technical solutions:

[0008] The invention provides an iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emission, comprising batching, primary mixing, secondary mixing, distribution, ignition and sintering steps, wherein low-carbon alcohol is added in the secondary mixing step.

[0009] Furthermore, based on the total mass of the sintering mixture, the added amount of the low-carbon alcohol accounts for 0.17-4.6% of the sintering mixture.

[0010] Furthermore, based on the total mass of the sintering mixture, the added amount of the low-carbon alcohol accounts for 0.46-0.69% of the sintering mixture.

[0011] Furthermore, the low-carbon alcohol is at least one of methanol, ethanol, ethylene glycol, and propanol;

[0012] The low-carbon alcohol is added by spraying.

[0013] Further, the solid fuel accounts for 3-8% of the sintering mixture based on the total mass of the sintering mixture.

[0014] Further, the solid fuel accounts for 4-6% of the sintering mixture based on the total mass of the sintering mixture.

[0015] Furthermore, the ignition temperature of the ignition step is 1050-1250° C., and the ignition time is 90-120 seconds.

[0016] Furthermore, the sintering pressure is 6-10 kPa.

[0017] Furthermore, in the material laying step, the material layer thickness is 500-800 mm.

[0018] Furthermore, in the iron ore sintering method provided by the present invention that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions, the other components of the sintering mixture used can be calculated in the same manner as in conventional processes, and there is no significant difference. Specifically, the sintering mixture may also include the following raw materials in percentage by mass:

[0019] Iron ore powder 52-60%;

[0020] Return of ore 10-14%;

[0021] Flux 6-8%;

[0022] Water 7-9%.

[0023] Furthermore, the sintering mixture may also include powder ore A, which is at least one of water-washed material, tank return material, magnesia powder, dust removal ash, and steel slag. The water-washed material is purchased from the market; the tank return material is from the ore returned from the blast furnace tank; the dust removal ash is from the fly ash collected by the dust removal equipment; and the steel slag is purchased from the market.

[0024] In the present invention, the flux is at least one of quicklime, limestone, dolomite and serpentine; the solid fuel is coke powder and / or coal.

[0025] In the present invention, the operations of primary mixing and secondary mixing are not significantly different from the mixing in the sintering step of conventional iron ore, except that low-carbon alcohol is sprayed in the secondary mixing.

[0026] The technical solution of the present invention has the following advantages:

[0027] 1. The present invention provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions, comprising batching, primary mixing, secondary mixing, distribution, ignition, and sintering steps, wherein low-carbon alcohol is added in the secondary mixing step. The inventor has found through research that adding an appropriate amount of low-carbon alcohol to the secondary mixing can adjust the sintering temperature of the sintering process and extend the sintering time, which can not only improve the reducibility of the sintered ore, but also significantly reduce the emission of nitrogen oxides. Specifically, the ferrous oxide content in the sintered ore can be reduced from 11% to 9.6% compared with the blank test, and the reducibility of the sintered ore is significantly improved; at the same time, compared with the blank test, the total concentrations of nitrogen monoxide and nitrogen oxides in the sintering flue gas have decreased, the NO concentration has decreased by 21.4%, and the NOx concentration has decreased by 19.5%; the average concentrations of NO and NOx have decreased by 16.5% and 13.3%, respectively. It can be seen that after adding low-carbon alcohols in the secondary mixing step, the concentration of nitrogen oxides has been significantly reduced, which fully demonstrates that adding low-carbon alcohols to the sintering mixture also has a good effect on reducing nitrogen oxide emissions. At the same time, low-carbon alcohols are an important chemical raw material and a high-quality liquid fuel with a high calorific value. Adding an appropriate amount of low-carbon alcohols can also reduce the amount of some solid fuels.

[0028] The present invention provides an iron ore sintering method capable of simultaneously improving the reducibility of the sintered ore and reducing the emission of nitrogen oxides. By limiting the amount of low-carbon alcohol used, the reducibility of the sintered ore can be further improved and the content of nitrogen oxides in the iron ore sintering process can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a graph showing changes in nitrogen oxide concentration in a blank control experiment of the present invention;

[0031] Figure 2 This is a graph showing changes in nitrogen oxide concentration in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0033] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0034] Example 1

[0035] This embodiment provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The specific operating steps are as follows:

[0036] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0037] Primary mixing: manually mix 41.48kg iron ore powder, 2.63kg washed material, 4.73kg tank return material, 1.47kg magnesia powder, 0.26kg dolomite powder, 0.79kg dust ash and 1.16kg steel slag.

[0038] Secondary mixing: add 52.52 kg of the first mixed material to 8.4 kg of returned ore, 4.9 kg of quicklime, 1.4 kg of dust removal ash, 2.4 kg of coke powder, and 5.6 kg of water, continue mixing and granulating, and spray 0.48 kg of methanol.

[0039] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, with a thickness of about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0040] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1100±50℃, and the ignition time is 2min.

[0041] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0042] Example 2

[0043] This embodiment provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The specific operating steps are as follows:

[0044] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0045] Primary mixing: manually mix 41.48kg iron ore powder, 2.63kg washed material, 4.73kg tank return material, 1.47kg magnesia powder, 0.26kg dolomite powder, 0.79kg dust ash and 1.16kg steel slag.

[0046] Secondary mixing: add 8.4 kg of return ore, 4.9 kg of quicklime, 1.4 kg of dust removal ash, 2.52 kg of coke powder, and 5.6 kg of water to 52.52 kg of the first mixed material, continue mixing and granulating, and spray 0.32 kg of methanol.

[0047] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, and the thickness is generally about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0048] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1100±50℃, and the ignition time is 2min.

[0049] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0050] Example 3

[0051] This embodiment provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The specific operating steps are as follows:

[0052] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0053] Primary mixing: manually mix 42kg iron ore powder, 2.54kg washed material, 5kg tank return material, 1.64kg magnesia powder, 0.23kg dolomite powder, 0.82kg dust ash and 1.10kg steel slag.

[0054] Secondary mixing: add 8.2kg of return ore, 4.8kg of quicklime, 1.35kg of dust removal ash, 2.6kg of coke powder, and 5.3kg of water to 53.33kg of the first mixed material, continue mixing and granulating, and spray 0.45kg of methanol.

[0055] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, and the thickness is generally about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0056] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1100±50℃, and the ignition time is 2min.

[0057] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0058] Example 4

[0059] This embodiment provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The specific operating steps are as follows:

[0060] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0061] Primary mixing: manually mix 43.4kg iron ore powder, 2.82kg washed material, 4.90kg tank return material, 1.47kg magnesia powder, 0.26kg dolomite powder, 0.93kg dust ash and 1.55kg steel slag.

[0062] Secondary mixing: add 55.33kg of the first mixed material to 9.8kg of returned ore, 5.6kg of quicklime, 1.4kg of dust ash, 4.2kg of coke powder, and 5.6kg of water, continue mixing and granulating, and spray 0.48kg of methanol.

[0063] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, and the thickness is generally about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0064] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1200±50℃, and the ignition time is 2min.

[0065] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0066] Example 5

[0067] This embodiment provides an iron ore sintering method that can simultaneously improve the reducibility of sintered ore and reduce nitrogen oxide emissions. The specific operating steps are as follows:

[0068] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0069] Primary mixing: manually mix 40.6kg iron ore powder, 2.4kg washed material, 4.3kg tank return material, 1.38kg magnesia powder, 0.20kg dolomite powder, 0.67kg dust ash and 1.05kg steel slag.

[0070] Secondary mixing: add 50.6 kg of the first mixed material to 7.1 kg of returned ore, 4.2 kg of quicklime, 1.4 kg of dust ash, 2.4 kg of coke powder, and 4.3 kg of water, and continue mixing and granulating, and spray 0.32 kg of methanol.

[0071] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, and the thickness is generally about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0072] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1200±50℃, and the ignition time is 2min.

[0073] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0074] Comparative Example 1

[0075] This comparative example provides an iron ore sintering method, and the specific operating steps are as follows:

[0076] Ingredients: Quality batching method, each raw material is mixed in a certain proportion.

[0077] Primary mixing: manually mix 41.48kg iron ore powder, 2.63kg washed material, 4.73kg tank return material, 1.47kg magnesia powder, 0.26kg dolomite powder, 0.79kg dust ash and 1.16kg steel slag.

[0078] Secondary mixing: add 8.4kg of return ore, 4.9kg of quicklime, 1.4kg of dust removal ash, 2.4kg of coke powder and 5.6kg of water to 52.5kg of the first mixed material and continue mixing and granulating.

[0079] Material distribution: 10-16mm sintered ore is placed on the grate bars of the sintering cup as the base material, with a thickness of about 20mm. The size of the sintering cup is Φ300×1000mm, and the second mixed material obtained by mixing and granulating is placed in the sintering cup, and the thickness of the sintering material is 700mm.

[0080] Ignition: The fuel used for ignition is liquefied petroleum gas, the ignition temperature is 1100±50℃, and the ignition time is 2min.

[0081] Sintering: After ignition, the exhaust fan air volume is 20% of the rated power of the Roots blower, and the negative pressure is generally 6-10kPa. After sintering, when the vacuum chamber temperature reaches the maximum temperature and then drops by 100℃, the sintering process is over.

[0082] Experimental example

[0083] 1. Test of nitrogen oxides in sintering flue gas

[0084] The concentration of nitrogen oxides in the sintering flue gas was measured by a CHEMIST 600 portable flue gas analyzer produced by Seitron.

[0085] After testing, the total concentration of nitric oxide, nitrogen dioxide and nitrogen oxides in the sintering flue gas in Comparative Example 1 (blank control) is as follows: Figure 1 As shown; nitrogen dioxide concentration is 2mg / m 3 The concentration of nitric oxide is low at the beginning, and then it increases, reaching a peak around the 6th minute and maintaining at 200 mg / m 3 The highest concentration of NO is 220 mg / m 3 , began to decrease gradually at the 18th minute and dropped to 1 mg / m at the 30th minute. 3 , at this time sintering is completed. NO x The emission pattern is similar to that of NO. xThe highest concentration reached 339 mg / m 3 It can be seen that the nitrogen oxides in the sintering process mainly come from nitric oxide. In addition, the average concentration of NO is about 114.8 mg / m 3 , NO x The average concentration was 177.7 mg / m 3 In Example 1, the nitrogen monoxide in the sintering fume increased sharply from the start of sintering to the first 4 minutes, and then showed a steady growth trend after 4 minutes, reaching a maximum of 173 mg / m around the 17th minute. 3 , indicating that the environmental conditions around the 17th minute are most conducive to the formation of nitric oxide. Combined with the sintering temperature curve, it can be analyzed that around the 17th minute, the sintering temperature reaches the highest temperature in the entire sintering process, and the oxygen concentration is the lowest at this time. In the later stage of sintering, the concentration of nitric oxide drops rapidly, and the sintering lasts for about 25 minutes; the nitrogen dioxide content is still very low, and the highest value appears at around 21 minutes, with a maximum value of 21mg / m 3 The total concentration of nitrogen oxides was consistent with that of nitric oxide, and increased rapidly to 209 mg / m 4 minutes before sintering. 3 , and then it showed a steady growth trend, reaching a maximum of 273mg / m at 18 minutes 3 .

[0086] Comparison of the data of Example 1 and Comparative Example 1 shows that the total concentrations of nitric oxide and nitrogen oxides have decreased, with the highest concentrations being 173 mg / m 3 , 21mg / m 3 , 273mg / m 3 , NO concentration decreased by 21.4%, NO x The concentration decreased by 19.5%, and the NO2 concentration was higher than that in the experiment without replacing coke powder. x The average concentration was 95.9 mg / m 3 and 154.1 mg / m 3 , respectively reduced by 16.5% and 13.3%, which fully demonstrates that adding low-carbon alcohols to the mixture has a good effect on reducing nitrogen oxide emissions. Other embodiments can also significantly reduce the total concentration and average concentration of nitrogen monoxide and nitrogen oxides in sintering flue gas, and the reduction level is equivalent to that of Example 1, which will not be repeated here.

[0087] 2. Test of ferrous oxide content in sintered ore

[0088] The FeO content in the sintered ore was determined by X-ray fluorescence spectrometer.

[0089] Table 1

[0090] Test Case FeO content, % Test Case FeO content, % Example 1 9.6 Example 4 10.13 Example 2 9.74 Example 5 9.80 Example 3 9.88 Comparative Example 1 11.0

[0091] From the data in the table, it can be seen that after low-carbon alcohol is used to replace coke powder, the FeO content decreases. The best solution is Example 1, in which the FeO content decreases from 11% to 9.6%. The reducibility of the sintered ore is significantly improved, which can reduce the amount of coke used in the blast furnace ironmaking process.

[0092] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. An iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions, comprising batching, primary mixing, secondary mixing, material distribution, ignition, and sintering steps, characterized in that: Adding low carbon alcohol in the secondary mixing step; Based on the total mass of the sintering mixture, the addition amount of the low-carbon alcohol accounts for 0.46-0.69% of the sintering mixture; the solid fuel accounts for 3-8% of the sintering mixture; The solid fuel is coke powder and / or coal.

2. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 1, characterized in that: The low-carbon alcohol is at least one of methanol, ethanol, ethylene glycol and propanol.

3. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to any one of claims 1 or 2, characterized in that: The low-carbon alcohol is added in a spraying manner.

4. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 1, characterized in that: Based on the total mass of the sintering mix, the solid fuel accounts for 4-6% of the sintering mix.

5. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 1, characterized in that: The ignition temperature of the ignition step is 1050-1250° C., and the ignition time is 90-120 seconds.

6. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 5, characterized in that: The sintering pressure is 6-10kPa.

7. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 5, characterized in that: In the material distribution step, the material layer thickness is 500-800 mm.

8. The iron ore sintering method capable of simultaneously improving the reducibility of sintered ore and reducing nitrogen oxide emissions according to claim 1, characterized in that: The sintering mixture also includes the following raw materials in percentage by weight: Iron ore powder 52-60%; Return of ore 10-14%; Flux 6-8%; Water 7-9%.

Images