Method for increasing ferrous content of sintered ore produced by hot air sintering

Abstract

The invention discloses a method for increasing the ferrous content of sintered ore produced by hot air sintering, and belongs to the field of iron and steel metallurgy sintered pellets, and the method comprises the following steps: burdening and uniformly mixing raw materials for sintering; the fuel content in the raw materials for sintering is 2-6%, and the fuel comprises 90-95% of fuel with a high heating value and 5-10% of fuel with a low heating value; the particle size composition of the fuel with the high heating value meets the following requirements that the proportion of the part with the particle size larger than 5 mm does not exceed 5%, and the proportion of the part with the particle size smaller than 3 mm is 80-95%; the particle size composition of the low-calorific-value fuel meets the following requirements: the proportion of the part with the particle size greater than 5mm is not less than 30%; and hot air sintering. The method has the beneficial effects that by adjusting the hot air sintering fuel structure and utilizing the rule that coarse particles segregate towards the sintering lower material layer in the sintering multi-roller material distribution process, more fuels with low heating values are distributed on the lower portion of the sintering material layer, heat of the lower material layer is reduced, and therefore the temperature of sintered ore of the sintering lower material layer is reduced, and the sintering efficiency is improved. And therefore, the reoxidation of FeO in the sintered ore is reduced.

Description

Technical Field

[0001] The invention relates to the field of sintering pellets in iron and steel metallurgy, and in particular to a method for increasing the ferrous content of sintered ore produced by hot air sintering. Background Art

[0002] At present, most domestic steel enterprises only use the hot waste gas in the high temperature zone (above 300℃) of the ring cooler for the utilization of the waste heat of the ring cooler. The main way to recycle it is to generate electricity after producing steam through the waste heat boiler. This method can utilize about 40% of the hot waste gas of the ring cooler, which can make the thermal efficiency of the whole plant reach 20%, and is adopted by most steel enterprises. However, due to the low temperature, difficulty and high cost of utilizing the hot waste gas of the ring cooler in the low temperature zone below 300℃, most enterprises do not consider it and directly discharge it to the atmosphere, which not only wastes the waste heat resources of the waste gas, but also causes thermal pollution to the environment and the emission of particulate matter does not meet the standards. At the same time, due to the segregation of the material and the automatic heat storage effect in the sintering production, the lower part of the material layer has excess heat and high temperature, while the upper part of the material layer has insufficient heat and low temperature. At the same time, the upper part of the material layer is rapidly cooled by the introduction of cold air, so that the liquid phase of the sintered ore has no time to crystallize, forming a large amount of glass and generating large internal stress and cracks, which reduces the strength of the surface sintered ore.

[0003] Based on the above background, a hot air sintering process has been proposed in the prior art. The hot air sintering technology mainly utilizes the high-temperature exhaust gas of the ring cooler to heat the sintering material layer for sintering. At present, there are many studies on hot air sintering, and the research on hot air process parameters focuses on the hot air temperature, hot air time, hot air area, hot air position and other process parameters. The research on the effect of hot air sintering on the sintering process is mostly focused on the effect of hot air sintering on the change of the material layer temperature during the sintering process and the oxygen content supply during the sintering process, and the appropriate oxygen content is proposed in a targeted manner. After the hot air sintering process of TISCO 450m2 was adopted, due to the volume expansion after the flue gas temperature increased, the total amount of oxygen involved in the sintering process was reduced to 91% before hot air sintering. The document "Research on Reasonable Oxygen Content and Temperature Control for Recycling of Sintering Large Flue Waste Gas" proposed the appropriate circulating air temperature and oxygen content for hot air sintering.

[0004] Research on the impact of hot air sintering on the quality of sintered ore has mostly focused on the impact on solid fuel consumption and the impact on the FeO content of sintered ore. Studies have shown that the application of hot air sintering technology can introduce the physical heat of hot air into the ore layer, and reduce the consumption of solid fuel by replacing the combustion heat of the fuel. While reducing the consumption of solid fuel, the sintering atmosphere is affected, causing the reduction zone phase to be relatively reduced, the oxygen level in the sintering process to be improved, and the oxidizing atmosphere to be enhanced, which will promote the reoxidation of low-valent iron oxides and reduce the FeO content of the sintered ore. However, the blast furnace has a certain range of requirements for the FeO content of the sintered ore, which cannot be too low or too high. Hot air sintering will reduce the FeO content of the sintered ore. How to increase the FeO content of the sintered ore when the FeO content of the sintered ore is lower than the content required by the blast furnace has not been studied yet.

[0005] In view of this, the inventor conducted in-depth research on this demand, and thus the present case was produced. Summary of the invention

[0006] Aiming at the problem that after hot air sintering in the prior art, the carbon content in the sintering process is reduced, the reducing atmosphere is weakened, and the FeO content in the sintered ore is reduced, and after hot air sintering, the ore temperature of the sintered ore is increased, resulting in increased FeO reoxidation and reduced FeO content, the present invention provides a method for increasing the ferrous content of sintered ore produced by hot air sintering, which can reduce the consumption of solid fuel without reducing the FeO content, thereby achieving the purpose of reducing consumption while meeting the needs of blast furnace production. The specific technical scheme is as follows:

[0007] A method for increasing the ferrous content of sintered ore produced by hot air sintering, comprising the following steps:

[0008] Step 1: batching and mixing the raw materials for sintering; before batching, the fuel is crushed by a fuel crusher, and the particle size of the fuel is made finer by controlling the parameters of the fuel crusher, so that the number of fuel particles is greater under the same fuel mass ratio, and thus the number of fuel particle distribution points is greater, the more reducing atmosphere is distributed, and the more FeO is generated; and the more fuel distribution points, the more uniform the fuel distribution, and thus the more uniform the heat distribution, the more uniform the sintering ore temperature, the less local high temperature, and the reoxidation of FeO in the sintering ore can be reduced.

[0009] The fuel content in the sintering raw material is 2-6% by mass, and the fuel includes 90-95% of high calorific value fuel and 5-10% of low calorific value fuel;

[0010] The particle size composition of the high calorific value fuel meets the following requirements: the particle size fraction larger than 5 mm does not exceed 5%, and the particle size fraction smaller than 3 mm is between 80% and 95%;

[0011] The particle size composition of the low calorific value fuel meets the following requirements: the particle size fraction larger than 5 mm is not less than 30%;

[0012] Step 2: hot air sintering.

[0013] By adjusting the fuel structure of hot air sintering and utilizing the rule that coarse particles segregate to the lower sintering layer during the multi-roller distribution process, more fuel with low calorific value is distributed in the lower part of the sintering layer, reducing the heat of the lower layer, thereby lowering the sintering ore temperature in the lower layer and reducing the reoxidation of FeO in the sintered ore.

[0014] The particle sizes of high calorific value fuel and low calorific value fuel are designed so that coarse particles account for a larger proportion in low calorific value fuel and a smaller proportion in high calorific value fuel. As a result, coarse particles with larger particle sizes will segregate to the lower material layer of sintering in the distribution process, forming a fuel structure with coarser particles in the lower material layer and finer particles in the upper material layer, that is, a fuel structure with more low calorific value fuel distributed in the lower particle layer, which reduces the heat of the lower material layer and thus reduces the sintering ore temperature of the lower material layer.

[0015] Preferably, the particle size composition of the high calorific value fuel in the fuel meets the following requirements:

[0016] The particle size of particles larger than 5mm shall not exceed 5% and shall not be less than 3%, and the particle size of particles smaller than 3mm shall be between 80% and 90%;

[0017] The particle size composition of the low calorific value fuel in the fuel meets the following requirements: the particle size fraction larger than 5 mm is not less than 30% and not more than 45%.

[0018] Preferably, the particle size composition of the high calorific value fuel also meets the following requirements: the particle size fraction smaller than 0.5 mm does not exceed 30%;

[0019] Preferably, the particle size composition of the high calorific value fuel also meets the following requirements: the particle size fraction smaller than 0.5 mm does not exceed 30% and is not less than 20%.

[0020] Preferably, the proportion of particles larger than 5 mm in the fuel is not less than 6%.

[0021] Preferably, the high calorific value fuel is one or both of coal powder and coke powder, and the low calorific value fuel is one or a combination of two or more of waste activated carbon powder from the flue gas purification system of the sintering plant, waste adsorbent activated carbon produced by the coal gas hydrogen production process, and coke produced by the coal gas hydrogen production process.

[0022] Preferably, the calorific value of the high calorific value fuel is greater than 27MJ / kg, and the calorific value of the low calorific value fuel is between 15-27MJ / kg;

[0023] Preferably, the calorific value of the low calorific value fuel is 17-26 MJ / kg, and the calorific value of the high calorific value fuel is 28-40 MJ / kg.

[0024] Preferably, in step 2, hot air sintering is performed using circulating hot flue gas, so that the thickness of the red layer in the combustion zone at the end of the sintering machine is 20%-50%.

[0025] Preferably, the fuel content in the sintering raw material is 2-6% by mass, preferably 3-5%.

[0026] Preferably, before hot air sintering, multi-roller distribution is used to make the coarse particles larger than 5 mm in size segregate to the lower sintering material layer, and more low calorific value fuel is distributed in the lower part of the sintering material layer.

[0027] The beneficial effects produced by the technical solution of the present invention are as follows:

[0028] (1) By adjusting the fuel structure of hot air sintering and utilizing the rule that coarse particles segregate to the lower sintering layer during the multi-roller distribution process, more low calorific value fuel is distributed in the lower part of the sintering layer, reducing the heat of the lower layer, thereby reducing the sintering temperature of the lower layer, thereby reducing the reoxidation of FeO in the sintered ore.

[0029] (2) The fuel is crushed by a fuel crusher. By controlling the parameters of the fuel crusher, the fuel particle size is made finer, so that the number of fuel particles is greater under the same fuel mass ratio, and the fuel particles are distributed at more points, the more reducing atmosphere is distributed, and the more FeO is generated; and the more points the fuel is distributed, the more uniform the fuel distribution is, and thus the more uniform the heat distribution is, the more uniform the sintering ore temperature is, the less local high temperature is, and the reoxidation of FeO in the sintering ore is reduced.

[0030] (3) The particle sizes of high calorific value fuel and low calorific value fuel are designed so that the proportion of coarse particles in low calorific value fuel is larger and the proportion of coarse particles in high calorific value fuel is smaller. As a result, the coarse particles with larger particle sizes will be segregated to the lower material layer of sintering during the distribution process, forming a fuel structure in which the lower material layer has coarser particles and the upper material layer has finer particles, that is, a fuel structure in which more low calorific value fuel is distributed in the lower particle layer, thereby reducing the heat of the lower material layer and thus reducing the sintering ore temperature of the lower material layer.

[0031] (4) A certain proportion of low calorific value fuel is used here, and low calorific value secondary resources or low calorific value inferior fuel can be comprehensively utilized. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. 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.

[0033] This implementation method designs the particle size of high calorific value fuel and low calorific value fuel so that the proportion of coarse particles in low calorific value fuel is relatively large and the proportion of coarse particles in high calorific value fuel is relatively small, so that in the distribution process, the coarse particles with larger particle size are segregated to the lower material layer of sintering, forming a fuel structure with coarser particles distributed in the lower material layer and finer particles distributed in the upper material layer, that is, a fuel structure with more low calorific value fuel distributed in the lower particle layer, reducing the heat of the lower material layer, thereby reducing the sintering temperature of the sintered ore in the lower material layer of sintering, reducing the reoxidation of FeO in the sintered ore, and achieving the purpose of increasing the ferrous content of the sintered ore produced by hot air sintering. The specific implementation method is as follows:

[0034] A method for increasing the ferrous content of sintered ore produced by hot air sintering, comprising the following steps:

[0035] Step 1, preparing and mixing raw materials for sintering;

[0036] The fuel content in the sintering raw material is 2-6% by mass, and the fuel includes 90-95% of high calorific value fuel and 5-10% of low calorific value fuel;

[0037] The particle size composition of the high calorific value fuel meets the following requirements: the particle size fraction larger than 5 mm does not exceed 5%, and the particle size fraction smaller than 3 mm is between 80% and 95%;

[0038] The particle size composition of low calorific value fuel meets the following requirements: the particle size larger than 5mm is not less than 30%;

[0039] Step 2: hot air sintering.

[0040] As a preferred embodiment, the particle size composition of the high calorific value fuel in the fuel meets the following requirements:

[0041] The particle size of particles larger than 5mm shall not exceed 5% and shall not be less than 3%, and the particle size of particles smaller than 3mm shall be between 80% and 90%;

[0042] The particle size composition of the low calorific value fuel in the fuel meets the following requirements: the particle size portion larger than 5mm is not less than 30% and not more than 45%.

[0043] In order to optimize the fuel structure, the content of fine particles is further limited here. The particle size composition of the high calorific value fuel also meets the following requirements: the particle size fraction less than 0.5 mm does not exceed 30%;

[0044] As a preferred embodiment, the particle size composition of the high calorific value fuel also meets the following requirements: the particle size fraction smaller than 0.5 mm does not exceed 30% and is not less than 20%.

[0045] As a preferred embodiment, the proportion of particles larger than 5 mm in the fuel is not less than 6%, that is, the proportion of particles larger than 5 mm in the mixed fuel of high calorific value fuel and low calorific value fuel is not less than 6%.

[0046] As a preferred embodiment, the high calorific value fuel is one or both of coal powder and coke powder, and the low calorific value fuel is one or a combination of two or more of waste activated carbon powder from a sintering plant flue gas purification system, waste adsorbent activated carbon produced by a coal gas hydrogen production process, and coke produced by a coal gas hydrogen production process.

[0047] As a preferred embodiment, the calorific value of the high calorific value fuel is greater than 27MJ / kg, and the calorific value of the low calorific value fuel is between 15-27MJ / kg;

[0048] Preferably, the calorific value of the low calorific value fuel is 17-26 MJ / kg, and the calorific value of the high calorific value fuel is 28-40 MJ / kg.

[0049] In actual operation, the red layer of the terminal combustion zone of the sintering machine refers to the thickness of the material layer that is still in the burning state when the sintering machine burns to the bottom layer. Usually, the thickness of the terminal combustion zone red layer needs to be less than 50%. When the fuel structure is not good and the ferrous content of the sintered ore needs to meet the standard, it is difficult to achieve a thickness of less than 50% of the terminal combustion zone red layer. Here, circulating hot flue gas is used for hot air sintering. By adjusting the fuel structure and controlling the particle size composition of the fuel, the fuel particle size is finer, the combustion time is shorter, and the combustion zone is narrower, that is, the thickness of the combustion zone red layer is smaller; at the same time, more low calorific value fuel is distributed in the lower sintering material layer, the sintering material layer temperature is reduced, and the combustion zone can also be narrowed, thereby controlling the thickness of the terminal combustion zone red layer of the sintering machine to 20%-50%.

[0050] As a preferred embodiment, the fuel content in the sintering raw material is 2-6% by mass, preferably 3-5%.

[0051] As a preferred embodiment, before hot air sintering, multi-roller distribution is used to make the coarse particles larger than 5 mm in size segregate to the lower sintering material layer, and more low calorific value fuel is distributed in the lower part of the sintering material layer.

[0052] The beneficial effects of the method for increasing the ferrous content of sintered ore produced by hot air sintering in this embodiment are further reviewed below through several groups of examples and comparative examples.

[0053] Embodiment 1:

[0054] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0055] Step S1, preparing and mixing raw materials for sintering;

[0056] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 92.40% of high calorific value fuel and 7.60% of low calorific value fuel;

[0057] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 4.73% of the particle size larger than 5mm, 86.15% of the particle size smaller than 3mm, and 27.04% of the particle size smaller than 0.5mm.

[0058] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 39.26%;

[0059] The proportion of particles larger than 5 mm in the fuel is 7.35%.

[0060] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 47%.

[0061] Embodiment 2:

[0062] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0063] Step S1, preparing and mixing raw materials for sintering;

[0064] The fuel content in the sintering raw material is 3.62% by mass, and the fuel includes 90.57% of high calorific value fuel and 9.43% of low calorific value fuel;

[0065] The high calorific value fuel is coke powder, a common fuel for sintering. The calorific value of the high calorific value fuel is 29.53MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is as follows: 4.96% of the particles are larger than 5mm, 83.74% of the particles are smaller than 3mm, and 25.62% of the particles are smaller than 0.5mm.

[0066] The low calorific value fuel is waste adsorbent activated carbon produced in the coal gas hydrogen production process. The calorific value of the low calorific value fuel is 19.54MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size portion larger than 5mm accounts for 37.61%;

[0067] The proportion of particles larger than 5 mm in the fuel is 8.04%.

[0068] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 41%.

[0069] Embodiment 3:

[0070] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0071] Step S1, preparing and mixing raw materials for sintering;

[0072] The fuel content in the sintering raw material is 3.32% by mass, and the fuel includes 93.18% of high calorific value fuel and 6.82% of low calorific value fuel;

[0073] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 28.76MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 4.13% of the particle size larger than 5mm, 88.94% of the particle size smaller than 3mm, and 29.13% of the particle size smaller than 0.5mm.

[0074] The low calorific value fuel is waste coke produced by the coal gas hydrogen production process. The calorific value of the low calorific value fuel is 25.17MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 41.24%;

[0075] The proportion of particles larger than 5 mm in the fuel is 6.66%.

[0076] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 37%.

[0077] Comparative Example 1:

[0078] The method for producing sintered ore by hot air sintering in this comparative example comprises the following steps:

[0079] Step S1, preparing and mixing raw materials for sintering;

[0080] The fuel content in the sintering raw material is 3.51% by mass, and the fuel is anthracite, which is a common fuel for sintering, and the calorific value of anthracite is 30.12 MJ / kg; after the conventional fuel crushing process, the fuel particle size composition is as follows: the particle size portion greater than 5 mm is 9.12%, the particle size portion less than 3 mm is 74.85%, and the particle size portion less than 0.5 mm is 22.48%;

[0081] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 52%.

[0082] Comparative Example 2:

[0083] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0084] Step S1, preparing and mixing raw materials for sintering;

[0085] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 87.15% of high calorific value fuel and 12.85% of low calorific value fuel;

[0086] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 4.73% of the particle size larger than 5mm, 86.15% of the particle size smaller than 3mm, and 27.04% of the particle size smaller than 0.5mm.

[0087] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 39.26%;

[0088] The proportion of particles larger than 5 mm in the fuel is 9.16%.

[0089] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine end point is 45%.

[0090] Comparative Example 3:

[0091] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0092] Step S1, preparing and mixing raw materials for sintering;

[0093] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 95.80% of high calorific value fuel and 4.20% of low calorific value fuel;

[0094] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 4.73% of the particle size larger than 5mm, 86.15% of the particle size smaller than 3mm, and 27.04% of the particle size smaller than 0.5mm.

[0095] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 39.26%;

[0096] The proportion of particles larger than 5 mm in the fuel is 6.18%.

[0097] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine end point is 44%.

[0098] Comparative Example 4:

[0099] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0100] Step S1, preparing and mixing raw materials for sintering;

[0101] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 92.40% of high calorific value fuel and 7.60% of low calorific value fuel;

[0102] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 4.73% of the particle size larger than 5mm, 86.15% of the particle size smaller than 3mm, and 27.04% of the particle size smaller than 0.5mm.

[0103] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 25.36%;

[0104] The proportion of particles larger than 5 mm in the fuel is 6.29%.

[0105] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 40%.

[0106] Comparative Example 5:

[0107] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0108] Step S1, preparing and mixing raw materials for sintering;

[0109] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 92.40% of high calorific value fuel and 7.60% of low calorific value fuel;

[0110] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 10.54% of the particle size larger than 5mm, 78.32% of the particle size smaller than 3mm, and 20.67% of the particle size smaller than 0.5mm.

[0111] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 39.26%;

[0112] The proportion of particles larger than 5 mm in the fuel is 12.72%.

[0113] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine at the end is 56%.

[0114] Comparative Example 6:

[0115] The method for producing sintered ore by hot air sintering in this embodiment comprises the following steps:

[0116] Step S1, preparing and mixing raw materials for sintering;

[0117] The fuel content in the sintering raw material is 3.48% by mass, and the fuel includes 92.40% of high calorific value fuel and 7.60% of low calorific value fuel;

[0118] The high calorific value fuel is anthracite, a common fuel for sintering, and the calorific value of the high calorific value fuel is 30.24MJ / kg. After the conventional fuel crushing process, the particle size composition of the high calorific value fuel is: 2.79% of the particle size larger than 5mm, 92.14% of the particle size smaller than 3mm, and 36.72% of the particle size smaller than 0.5mm.

[0119] The low calorific value fuel is waste activated carbon powder from the flue gas purification system of the sintering plant. The calorific value of the low calorific value fuel is 17.96MJ / kg. After the conventional fuel crushing process, the particle size composition of the low calorific value fuel is as follows: the particle size greater than 5mm accounts for 39.26%;

[0120] The proportion of particles larger than 5 mm in the fuel is 5.56%.

[0121] Step S2, hot air sintering, uses circulating hot flue gas for hot air sintering, and the thickness of the red layer in the combustion zone of the sintering machine end point is 25%.

[0122] The FeO content of the sintered ores obtained in the above three groups of embodiments and six groups of comparative examples was tested, and the results were as follows:

[0123] Table 1 Detection results of FeO content in sintered ore

[0124] Example FeO content Example FeO content Example 1 7.61％ Comparative Example 3 7.12％ Example 2 8.13％ Comparative Example 4 6.98％ Example 3 8.23％ Comparative Example 5 5.82％ Comparative Example 1 5.45％ Comparative Example 6 5.37％ Comparative Example 2 5.62％

[0125] As shown in Table 1, it can be seen that the FeO content in the sintered ore obtained in Examples 1-3 reached more than 7.5%, which is significantly higher than the FeO content of the sintered ore in Comparative Examples 1-6. It can be seen that the sintered ore obtained by sintering the fuel structure formed by the combination of high calorific value fuel and low calorific value fuel in this case can increase the FeO content of the sintered ore.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for increasing the ferrous content of sintered ore produced by hot air sintering, characterized in that: The steps include: Step 1, preparing and mixing raw materials for sintering; The fuel content in the sintering raw material is 2-6% by mass, and the fuel includes 90-95% of high calorific value fuel and 5-10% of low calorific value fuel; The particle size composition of the high calorific value fuel meets the following requirements: the proportion of particles larger than 5 mm does not exceed 5%, and the proportion of particles smaller than 3 mm is 80-95%; The particle size composition of the low calorific value fuel meets the following requirements: the proportion of particles larger than 5 mm is not less than 30%; Step 2: hot air sintering.

2. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: The particle size composition of the high calorific value fuel in the fuel meets the following requirements: The particle size of particles larger than 5mm shall not exceed 5% and shall not be less than 3%, and the particle size of particles smaller than 3mm shall be between 80% and 90%; The particle size composition of the low calorific value fuel in the fuel meets the following requirements: the particle size fraction larger than 5 mm is not less than 30% and not more than 45%.

3. According to a method for increasing the ferrous content of sintered ore produced by hot air sintering in claim 1, the high calorific value fuel is one or both of coal powder and coke powder, and the low calorific value fuel is one or a combination of two or more of waste activated carbon powder from the flue gas purification system of the sintering plant, waste adsorbent activated carbon produced by the coal gas hydrogen production process, and coke produced by the coal gas hydrogen production process.

4. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: The proportion of particles larger than 5 mm in the fuel is not less than 6%.

5. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: The particle size composition of the high calorific value fuel also meets the following requirement: the particle size fraction smaller than 0.5 mm does not exceed 30%.

6. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: The high calorific value fuel has a calorific value greater than 27 MJ / kg, and the low calorific value fuel has a calorific value between 15 and 27 MJ / kg.

7. A method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 6, characterized in that: The calorific value of the low calorific value fuel is 17-26 MJ / kg, and the calorific value of the high calorific value fuel is 28-40 MJ / kg.

8. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: In step 2, hot air sintering is performed using circulating hot flue gas, so that the thickness of the red layer in the combustion zone of the sintering machine end point is 20%-50%.

9. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: Calculated by mass percentage, the fuel content in the sintering raw material is 3-5%.

10. The method for increasing the ferrous content of sintered ore produced by hot air sintering according to claim 1, characterized in that: Before hot air sintering, multi-roller distribution is used to make the coarse particles larger than 5mm in size segregate to the lower sintering material layer, and more low calorific value fuel is distributed in the lower part of the sintering material layer.