Fuel layered sintering method for ultra-thick material layer

Abstract

The fuel layered sintering method for ultra-thick material layers is to first evenly distribute the 10-16mm bottom material to the lower layer of the sintering machine trolley as the sintering machine trolley runs; then mix and granulate the mixed ore with a particle size range of 0-10mm, the internal fuel with a particle size of 0-5mm, the quicklime or lightly burned dolomite with a particle size of 0-3mm, the dolomite or limestone with a particle size of 0-3mm, and the return ore and dust removal ash with a particle size of 0-5mm, and evenly distribute it to the middle layer of the sintering machine trolley; then evenly distribute the external fuel with a particle size of 0-3mm to the upper layer of the sintering machine trolley. After the distribution is completed, the surface material is turned over and mixed by the roller sled device, and the flattening plate completes the flattening. After the treatment, the original sintered material enters the ignition furnace with the sintering machine trolley for ignition to complete the exhaust sintering process. The three-stage distribution achieves the purpose of improving the surface sintered ore quality and strengthening the redox atmosphere of the sintering process, while effectively reducing the sintering solid fuel consumption and saving energy and reducing carbon.

Description

Technical Field

[0001] The invention belongs to the field of metallurgical technology and is a method for reasonably distributing a certain proportion of sintering fuel on the upper layer of a sintering machine mixture before ignition to perform ignition sintering to improve the surface sintering ore quality and strengthen the redox atmosphere during the sintering process. Background Art

[0002] Carbon peak refers to the process in which the annual carbon dioxide emissions of a region or industry reach a historical high, then experience a plateau period and enter a continuous decline. It is a historical turning point in the transition from an increase to a decrease in carbon dioxide emissions, marking the decoupling of carbon emissions from economic development. The peak target includes the peak year and peak value; carbon neutrality offsets the CO2 emissions or total greenhouse gas emissions generated over a period of time through energy conservation and emission reduction, planting green plants, etc., to achieve zero emissions. According to the "2006 National Greenhouse Gas Emission Inventory Guidelines" published by the IPCC, the steel industry, as a major consumer of fossil energy and a major carbon emitter, will inevitably become the main target of carbon emission reduction. At the same time, the steel industry's carbon emission reduction is both an important measure to actively respond to climate change and an important challenge for sustainable development.

[0003] At present, various scientific research institutions or steel companies have developed various technologies such as layered distribution and segmented addition of fuel for sintering, in order to maximize the utilization of sintering solid fuels, thereby achieving energy conservation and carbon reduction. Among them, CN201910095844.1 discloses "a sintering method for layered distribution of fuel after pre-screening", which is a method of adding fuel to a mixer in stages to form a mixture of fuels with different mass ratios and then layering it on the sintering machine; CN202111568109.1 discloses "a method for strengthening sintering of the upper material layer", which is a method of layering the secondary and tertiary mixtures by using different proportions of ingredients for sintering. In the fuel layered sintering method of the above patent, the process method is deeply optimized through the basic principle of heat storage of the sintering material layer, but there are also major problems: first, the difficulty and investment of the patent are large, which is reflected in the need to build a complete batching room system on the basis of the original sintering workshop; second, the overall process flow is complicated, involving the production of a variety of mixed materials, etc., and the water vapor generated by the second-stage sintering will reduce the strength of the sintered ore in the lower layer that has been sintered, and increase the sintering return rate. Therefore, it is necessary to study a fuel layered sintering method that can be easily implemented and has good results, which can be used in actual production under the conditions of "double carbon" and the downward situation of steel enterprises, so as to achieve the purpose of sintering energy saving and carbon reduction. Summary of the invention

[0004] The purpose of the present invention is to provide a fuel layered sintering method for an ultra-thick material layer, so as to improve the surface sintered ore quality and strengthen the redox atmosphere during the sintering process, while effectively reducing the sintering solid fuel consumption, saving energy and reducing carbon.

[0005] The technical solution adopted by the present invention is:

[0006] The key process steps of the fuel layered sintering method for ultra-thick material layer include:

[0007] 1) Evenly distribute the 10~16mm granular base material to the lower layer of the sintering machine trolley as the sintering machine trolley runs;

[0008] 2) The mixed ore with a particle size range of 0-10mm, the internal fuel with a particle size of 0-5mm, the quicklime or lightly burned dolomite with a particle size of 0-3mm, the dolomite or limestone with a particle size of 0-3mm, and the return ore and dust ash with a particle size of 0-5mm are brought into the sintering workshop and stored in the corresponding ore slots in the sintering batching room. After being mixed and granulated into a mixed material, it is evenly distributed to the middle layer of the sintering machine trolley;

[0009] 3) Evenly distribute the 0~3mm external fuel to the upper layer of the sintering machine trolley, that is, the upper layer of the mixed material. After the distribution is completed, the surface materials are turned over and mixed by the roller sled device, and the flattening plate completes the flattening. After the treatment, the sintering raw materials enter the ignition furnace with the sintering machine trolley for ignition to complete the exhaust sintering process.

[0010] Furthermore, the thickness of the base material in step 1) is 50-100 mm; the thickness of the mixed material in step 2) is 850-950 mm, its moisture content is ≤6.4%, and the proportion of particle size ≥3 mm is more than 45%; the thickness of the external fuel in step 3) is 5-30 mm; the sintered original material layer after the material distribution is completed is controlled at 900-1000 mm.

[0011] Furthermore, the base material in step 1) is distributed through the fan-shaped gate of the ground paving silo; in step 2), the internal fuel accounts for 85% to 100% of the total sintering fuel ratio, and the external fuel accounts for 0% to 15% of the total sintering fuel ratio, and the mixture is distributed through the auxiliary distribution door, round roller, and nine rollers, and is loosened by the loosener; the external fuel in step 3) is distributed through the double screw feeder, and the roller sled device turns over the material at a depth of 10 to 50 mm on the surface and mixes it with the external fuel.

[0012] The external fuel in step 3) is selected from one or a mixture of coke powder, coal powder, biomass fuel, and semi-coke; the particle size of the external fuel is 0-3 mm, and the proportion of the external fuel with a particle size of 0-0.5 mm does not exceed 30%.

[0013] The present invention distributes fuel that meets certain particle size requirements evenly on the upper layer of low-moisture mixed material before the sintering machine trolley enters the ignition furnace through three-stage distribution, and controls the combustion speed and degree of the upper layer fuel by the slight negative pressure ignition intensity. Applying the sintering fuel layer distribution technology to actual sintering production can achieve the following beneficial effects:

[0014] (1) The external fuel layered on the upper layer of the mixture is ignited and burned continuously under a slight negative pressure, which inhibits the sudden drop in the temperature of the sintered ore on the surface of the sintering machine, improves the strength of the surface sintered ore, and reduces the amount of returned ore;

[0015] (2) The external fuel layered on the upper layer of the mixture is incompletely burned in the ignition furnace to produce CO, which diffuses out and flows into the mixture through exhaust air, improving the reducing atmosphere and thus improving FO X The degree of redox can enhance the sintering process;

[0016] (3) By distributing the coke powder, which accounts for 0% to 15% of the mixture, to the upper layer of the mixture, the fuel distribution during the sintering process is controlled, thereby improving the temperature field distribution during the sintering process, improving the sintering mineral and quality indicators, and reducing solid fuel consumption;

[0017] (4) Through this method, the amount of sintering return ore, the ignition furnace gas consumption and the sintering solid fuel consumption are all reduced, which can be achieved with low investment in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flow chart for fuel pre-screening.

[0019] Figure 2 This is the process flow chart of sintering with fuel added to the surface layer.

[0020] Figure 3 This is the sintering machine system layout diagram.

[0021] Figure 4 This is a diagram of the sintering machine mixture distribution system.

[0022] In the figure: 1-sintering machine; 2-ignition furnace; 3-bottom material bin; 4-coke powder bin; 5-mixing bin; 6-sintering machine feeding system; 7-sintering machine loosening device; 8-sintering machine feeding auxiliary door; 9-nine-roller feeding device; 10-round roller feeding device. DETAILED DESCRIPTION

[0023] The following is further described with reference to the examples in the accompanying drawings.

[0024] Example 1: Sintered cup test

[0025] Process steps:

[0026] 1) Conduct a benchmark sintering cup test to explore the optimal sintering utilization factor and sinter strength under normal fuel addition conditions;

[0027] 2) On this basis, by gradually reducing the amount of fuel in the mixture and increasing the amount of fuel in the upper layer, the optimal sintering parameters and sinter strength are gradually explored;

[0028] 3) The optimal parameters are used as a guide for further industrial trials. The industrial trials are described in Example 2.

[0029] Table 1 is the sintering cup test results of the fuel surface addition sintering process in Example 1. From Table 1, it can be seen that when the surface layer is added with coke powder to stabilize the total amount of fuel, the fuel ratio in the mixture is reduced to 83% (i.e. 3.32%), the drum strength is stabilized at about 67%, which is slightly lower than that of the whole coke, the changes in the utilization coefficient, the yield, the average particle size, the return rate, etc. are all small, the terminal temperature shows a downward trend, and the fuel consumption is significantly reduced; when the surface layer is added with coke powder to stabilize the total amount of fuel, the coke ratio of the mixture is reduced to 80% (i.e. 3.2%), the decline in drum strength becomes larger, the utilization coefficient and the yield rate decrease, and the return rate increases significantly and becomes larger and larger.

[0030] Table 1 Sintering cup test results before process modification

[0031] .

[0032] Example 2: Industrial test example

[0033] Figure 1 ~ Figure 4 As shown: The process steps include:

[0034] 1) Through three-stage distribution, the fuel that meets the requirements of a certain particle size range is evenly distributed on the upper layer of the low-moisture mixture before the sintering machine trolley enters the ignition furnace 2, and the combustion speed and degree of the upper layer fuel are controlled by the micro-negative pressure ignition intensity below -20pa. The key process steps include: evenly distributing the 10~16mm base material to the lower layer of the sintering machine trolley as the sintering machine trolley runs;

[0035] 2) Then, the mixed ore with a particle size range of 0-10mm, the internal fuel with a particle size of 0-5mm, the quicklime or lightly burned dolomite with a particle size of 0-3mm, the dolomite or limestone with a particle size of 0-3mm, and the returned ore and dust ash with a particle size of 0-5mm are brought into the sintering workshop and stored in the corresponding ore slots of the sintering batching room. After being mixed and granulated into a mixed material, it is transported to the mixed material bin 5, and then evenly distributed to the middle layer of the sintering machine trolley through the sintering machine distribution system 6;

[0036] 3) The 0~3mm external fuel is transported to the coke powder bin 4 through pneumatic ash conveying, and then evenly distributed to the upper layer of the sintering machine trolley, that is, the upper layer of the mixed material. After the distribution is completed, the surface material is turned over and mixed by the roller sled device, and the flattening plate completes the flattening. After the treatment, the sintered raw material enters the ignition furnace 2 with the sintering machine 1 trolley for ignition to complete the exhaust sintering process.

[0037] The thickness of the base material in step 1 is 50~100mm; the thickness of the mixed material is 850~950mm, its moisture content is ≤6.4%, and the proportion of particle size ≥3mm is more than 45%; the thickness of the external fuel is 5~30mm; the sintered original material layer after the material distribution is completed is controlled at 900~1000mm.

[0038] The base material in step 1) is distributed through the fan-shaped gate of the floor silo 3; the mixed material is distributed through the auxiliary distribution door 8, the round roller 10, and the nine rollers 9, and is loosened by the loosening device 7; the external fuel is distributed through the double screw feeder; the roller sled device turns over the material with a depth of 10 to 50 mm on the surface and mixes it with the external fuel; the internal fuel accounts for 85% to 100% of the total proportion of the sintering fuel, and the external fuel accounts for 0% to 15% of the total proportion of the sintering fuel.

[0039] Step 1) The bellows flaps of the sintering machine exhaust system can be controlled at an opening of 0~100%, among which the openings of 1#, 2#, and 3# bellows are controlled at 0%, 15%, and 30% respectively during normal production. The openings of the subsequent bellows are controlled at 100% during normal production. The first 1#~6# bellows are separated by soft magnetic sealing devices to ensure that there is no air leakage between the bellows, meeting the normal production micro-negative pressure ignition requirements after adding coke powder to the surface of the mixed material on the sintering machine trolley.

[0040] The external fuel is selected from one or a mixture of coke powder, coal powder, biomass fuel, and semi-coke; the particle size of the external fuel is 0-3 mm, and the proportion of 0-0.5 mm particle size of the external fuel does not exceed 30%; the external fuel is produced by a pre-screening system and transported by a pneumatic ash conveying system.

[0041] Table 2 is the industrial test results of the sintering workshop of the fuel surface layer addition process in Example 2. From Table 2, it can be seen that as the coke powder used in the upper layer increases from 0 t / h to 1.5 t / h, the total fuel ratio decreases from 3.82% to 3.57%, the sintering feed amount and drum strength are stable, the amount of returned ore and dust decreases, and the NOx and CO emission concentrations decrease, with obvious effects.

[0042] Table 2 Industrial test results

[0043] .

Claims

1. A fuel layered sintering method for ultra-thick material layers, characterized in that The key process steps include: 1) Evenly distribute the 10~16mm granularity bottom material to the lower layer of the sintering machine trolley as the sintering machine trolley runs, and the thickness of the bottom material is 50~100mm; 2) Mix the mixed ore with a particle size range of 0-10mm, the internal fuel with a particle size of 0-5mm, the quicklime or lightly burned dolomite with a particle size of 0-3mm, the dolomite or limestone with a particle size of 0-3mm, and the return ore and dust ash with a particle size of 0-5mm, and granulate them into a mixed material, which is evenly distributed on the middle layer of the sintering machine trolley; the thickness of the mixed material is 850-950mm, the moisture content is ≤6.4%, and the proportion of particles ≥3mm is more than 45%; 3) Evenly distribute the external fuel with a particle size of 0~3mm to the upper layer of the sintering machine trolley. After the distribution is completed, the surface materials are turned over and mixed by the roller sled device, and the flattening plate completes the flattening. After the treatment, the sintering raw materials enter the ignition furnace with the sintering machine trolley for ignition to complete the exhaust sintering process; the thickness of the external fuel is 5~30mm; the sintering raw material layer after the distribution is controlled at 900~1000mm.

2. The fuel layered sintering method of a material layer according to claim 1, characterized in that: The base material in step 1) is distributed through the fan-shaped gate of the ground silo; in step 2), the internal fuel accounts for 85% to 100% of the total sintering fuel ratio, and the external fuel accounts for 0% to 15% of the total sintering fuel ratio, and the mixture is distributed through the auxiliary distribution door, round roller, and nine rollers, and is loosened by the loosener; the external fuel in step 3) is distributed through the double screw feeder, and the roller sled device turns over the material at a depth of 10 to 50 mm on the surface and mixes it with the external fuel.

3. The fuel layered sintering method of the material layer according to any one of claims 1 to 2, characterized in that: The external fuel is selected from one or a mixture of coke powder, coal powder, biomass fuel, and semi-coke; the particle size of the external fuel is 0-3 mm, and the proportion of the external fuel with a particle size of 0-0.5 mm does not exceed 30%.

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