Sintered ore with CSN lump ore undersize powder instead of part of high-silicon barite and preparation method

Abstract

The invention provides sintered ore with CSN lump ore undersize powder replacing part of high-silicon baojie and a preparation method, and belongs to the technical field of metallurgical sintered ore. According to the method, the CSN lump ore undersize powder with the TFe content being not lower than 55%, the SiO2 content being not lower than 14.6% and the burning loss being within 4.3% is used for replacing part of high-silicon ore, and the proportion and moisture of the CSN lump ore undersize powder are controlled so that chemical components of the iron-containing blended ore for sintering can be controlled to reach a specific target range; meanwhile, by stabilizing the moisture content and the average particle size of the iron-containing blended ore for sintering and controlling SiO2 to be not lower than 5.4%, the non-uniformity of particle size influencing components is reduced, the caking performance in the sintering process and the generation amount of low-melting-point substances are enhanced, the amount of liquid phases generated in the sintering process is increased, the liquid phases are fully solidified, and the sintering quality of the iron-containing blended ore is improved. Therefore, the final sintering yield is promoted, the physical and chemical properties and metallurgical properties of the sintered ore are further improved, and meanwhile, the ore blending cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical sintering technology, specifically to a method for preparing sinter by replacing part of the high-silica coarse ore with CSN lump ore undersize powder. Background Technology

[0002] High-silica iron ore has a grade of around 61.5%, contains some limonite, and has good sintering properties, making it an important component of iron-containing ore in sintering blends. However, because it originates from Australia and requires long-distance transportation, it increases the cost of sintering blends and has a low SiO2 content. In the steel industry, to reduce costs, lower-priced iron ore powder is often used to replace some of the high-priced high-silica iron ore. However, low-priced iron ore powder often has high levels of impurities such as S and P, and low levels of TFe and SiO2. Using it in large proportions can lead to low sinter yield, decreased productivity, an excessive proportion of particles smaller than 10 mm in the finished ore, and deterioration of properties such as the Low Temperature Reduction Index (RDI) and drum strength, affecting the effectiveness of use and thus limiting its application, preventing a truly effective reduction in blending costs. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for replacing a portion of high-silica coarse sinter with CSN lump ore undersize powder and its preparation. By selecting an appropriate proportion of CSN lump ore undersize powder, this invention significantly reduces the amount of high-silica coarse sinter used. This reduces the proportion of particles smaller than 10 mm in the finished ore without lowering yield or production efficiency, thereby improving quality indicators such as the Low-Temperature Reduction Index (RDI) and drum strength of the sinter. This ensures stable and smooth blast furnace production while significantly reducing ore blending costs.

[0004] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0005] In a first aspect, the present invention provides a sintering iron-containing blended ore for which CSN lump ore undersize powder can replace part of the high-silica coarse powder, comprising the following raw materials by mass percentage: PB powder 11%-17%, BRBF powder 10%-19%, FMG mixed powder 14%-17%, high-silica coarse powder 1%-8%, CSN lump ore undersize powder 2%-6%, blast furnace return ore 14%-16%, Silk Road powder 10%-14%, direct-supply iron concentrate 5%-9%, domestic iron concentrate 3%-5%, Daye low-grade concentrate 1%-2%, lump ore return powder 2%-6%, and secondary resources 3%-5%;

[0006] The chemical composition of the iron-containing homogenized ore for sintering, by mass percentage, includes: TFe: 59.15%±0.3%, SiO2: 5.45%±0.2%, CaO: 2.3%±0.15%, S: 0.14%±0.05%, Al2O3: 2.12%±0.2%, and moisture: 7.9%±0.6%.

[0007] The BRBF powder has a TFe content greater than 62%, SiO2 content greater than 4.8%, a burn-off of 2.96%, and a cost per ton of ore of approximately 859.6 yuan. The high-silica coarse powder has a TFe content greater than 55%, SiO2 content greater than 13.7%, a burn-off of 4.52%, and a cost per ton of ore of approximately 646.9 yuan. Its burn-off is relatively high. When a large amount is added, the ore inventory is low, and the SiO2 content of the mixed ore is low, resulting in a low liquid phase content during the sintering process, which seriously affects the sintering productivity and the quality of the sintered ore. This invention uses CSN lump ore undersize powder with a TFe content of not less than 55%, SiO2 of not less than 14.6%, and burn loss of less than 4.3% to replace part of the high-silica coarse powder. By controlling the proportion and moisture content of the CSN lump ore undersize powder, the chemical composition of the iron-containing blended ore for sintering is controlled to reach a specific target range. At the same time, this invention reduces the impact of particle size on the non-uniformity of composition by stabilizing the moisture content and average particle size of the iron-containing blended ore for sintering, and by controlling SiO2 to not less than 5.4%. This enhances the agglomeration performance and the amount of low-melting-point substances generated during sintering, increases the amount of liquid phase generated during sintering, and allows the liquid phase to be fully solidified. This promotes the final sintering yield and further improves the physicochemical and metallurgical properties of the sintered ore, while significantly reducing the cost of ore blending.

[0008] Furthermore, the secondary resources include, but are not limited to, at least one of the following: ironmaking gas ash, iron oxide scale, dust removal ash, sludge, steel slag magnetic separation powder, and steel slag tailings.

[0009] Secondly, the present invention provides a CSN lump ore undersize powder to replace part of the high-silica coarse sinter. The raw materials include, by mass percentage: 81%-83% of the iron-containing blended ore for sintering, 13.6%-14% of flux and 4.4%-4.8% of solid fuel.

[0010] This invention uses CSN lump ore undersize powder to replace part of the high-silica coarse powder. As the proportion of CSN lump ore undersize powder used increases, the SiO2 content of the iron-containing blended ore used for sintering increases significantly, and the grade of the blended ore does not decrease. This invention further reduces the energy consumption of the sintering process by appropriately reducing the coal ratio (coal powder to coke powder ratio). At the same time, the increase in MgO content is beneficial to stabilizing iron oxides, which can both prevent the formation of secondary Fe2O3 during the cooling of sinter and prevent the low-temperature reduction of iron oxides in sinter, thus inhibiting the low-temperature reduction pulverization of sinter and improving the RDI index of sinter, which can meet the requirements of blast furnace production.

[0011] Furthermore, the raw materials for the sinter include: 81.65% iron-containing blended ore for sintering, 13.6% flux, and 4.75% solid fuel.

[0012] Furthermore, the raw materials for the sinter include: 82% iron-containing blended ore for sintering, 13.6% flux, and 4.4% solid fuel.

[0013] Furthermore, the raw materials for the sinter include: 81.45% iron-containing blended ore for sintering, 13.9% flux, and 4.65% solid fuel.

[0014] Furthermore, the raw materials for the sinter include: 81.75% iron-containing blended ore for sintering, 13.6% flux, and 4.65% solid fuel.

[0015] Further, the chemical composition of the sinter, by mass percentage, includes: TFe: 54.3%-55.0%, FeO: 7.7%-9.7%, SiO2: 5.9%-6.1%, CaO: 11.3%-11.6%, MgO: 1.9%-2.0%, Al2O3: 2.3%-2.4%, S≤0.035%, and basicity of 1.88-1.92. The magnitude and fluctuation of the basicity of the sinter are affected by the content of CaO, MgO, SiO2, and Al2O3. The amount of CaO, MgO, SiO2, and Al2O3 is mainly determined by the flux ratio. The flux can strengthen sintering and is indispensable. In this invention, quicklime, limestone, and dolomite in a mass ratio of (5.8%-6%):(2.0%-2.2%):5.8% are used as flux to stabilize the basicity of the sinter. The flux of this invention must meet the following conditions: (1) the proportion of limestone with a particle size <3 mm is not less than 90%, and the moisture content is ≤5%; (2) the proportion of quicklime with a particle size <3 mm is not less than 90%, CaO ≥83%, and activity ≥220; (3) the proportion of dolomite with a particle size <3 mm is not less than 90%, and the moisture content is ≤5%. Dolomite and limestone are transported to the batching tank by belt conveyor, and quicklime is directly sent to the batching tank by sealed tank truck and then compressed into the ore bin by compressed air through pipeline. The solid fuel used in this invention is a combination of coke powder and white coal. The coke powder is transported from the coking company and blast furnace bin to the coarse fuel bin in the sintering workshop by belt conveyor, and mixed coal gas is selected as the fuel for sintering ignition. The solid fuel of this invention must meet the following conditions: solid fuel particle size <25 mm; white coal moisture content <10%. After the solid fuel is crushed, the proportion of coke powder with a particle size less than 3 mm is 67%-77%, and the proportion of white coal with a particle size less than 3 mm is 63%-73%.

[0016] Furthermore, the flux comprises quicklime, limestone, and dolomite in a mass ratio of (5.8%-6%):(2.0%-2.2%):5.8%.

[0017] Furthermore, the solid fuel comprises pulverized coal and coke powder in a mass ratio of (2.2%-2.4%):(2.2%-2.4%).

[0018] Furthermore, the raw materials for the sintered ore also include return ore (here, return ore refers to internal return ore, which is the sintering screen undersize material), and the amount of return ore used is 18% of the total mass of the blended ore, flux and solid fuel (i.e., 18% of the return ore is externally added).

[0019] Thirdly, the present invention provides a method for preparing the CSN lump ore undersize powder to replace part of the high-silica coarse sinter, comprising the following steps:

[0020] (1) Prepare the ingredients according to the raw material ratio;

[0021] (2) The raw materials are mixed with water and granulated to obtain sintered material; wherein the mixing includes primary mixing and secondary mixing. In order to improve the mixing and granulation effect and increase the pelletizing rate of the mixture, the present invention has taken the following measures: a. Water is sprayed on the conveyor belt in front of the primary mixer to pre-digest quicklime, increase its digestion time, and reduce the destructive effect of its digestion and water absorption in the mixer on the pellets; b. The internal liner of the secondary mixer is modified from the conventional liner to the counter-current spiral liner, which extends the granulation time by 2-3 minutes. After testing, the pelletizing rate is increased by 3%-5%, which is a significant effect.

[0022] (3) Using 260 m 2 Sintering is carried out using a belt-type exhaust sintering machine, with the material layer thickness controlled at 840 mm, the ignition temperature at 1100±50℃, the ignition time at 50-70 s, the holding time at 1-2 min, and the final sintering temperature controlled at 370±30℃.

[0023] (4) Cooling to obtain CSN block ore undersize powder to replace part of the high-silica coarse sinter.

[0024] To maintain a "dynamic balance" system for sinter quality and output during stable blast furnace operation, this invention increases the ignition temperature from 1000±50℃ to 1100±50℃ compared to previous sintering processes; reduces the sintering machine vertical firing speed from 23 mm / min to 16 mm / min, and the machine speed from 1.95 m / min to 1.85 m / min; and increases the sintering endpoint temperature from 330±30℃ to 370±30℃.

[0025] During the sintering process, the thickness of the sinter layer, the sintering machine speed, and the final temperature are among the key parameters determining the quality of the sinter. This invention employs thick-layer sintering technology, controlling the sinter layer thickness to 840 mm, using mixed gas for ignition, controlling the machine speed to 1.85 m / min, and controlling the final temperature to 370±30℃, thus achieving stable sintering and optimized production. This invention precisely controls the aforementioned key parameters during the sintering process through the following operations:

[0026] 1. Exhaust temperature (exhaust gas temperature from the tail section air box) and endpoint temperature / location:

[0027] If the endpoint is reached ahead of schedule (early waste temperature peak, earlier endpoint position), it indicates that the sintering rate is too fast. The machine speed should be reduced or the material layer appropriately thickened (needing to be combined with negative pressure) to extend the sintering time and shift the endpoint later. If the endpoint is reached behind schedule (late waste temperature peak, later endpoint position), it indicates that the sintering rate is too slow. The sintering process can be accelerated by increasing the machine speed or appropriately thinning the material layer (needing to be combined with negative pressure) to move the endpoint earlier. If the endpoint temperature is too low, it indicates that combustion may be incomplete. The heat retention effect can be improved by thickening the material layer or slightly reducing the machine speed to extend the high-temperature holding time. If the endpoint temperature is too high / overburned, it indicates that the material layer may be too thick or the machine speed too slow. The temperature can be reduced by thinning the material layer or slightly increasing the machine speed.

[0028] 2. Negative pressure:

[0029] If the negative pressure rises abnormally, it indicates poor permeability of the material layer (e.g., excessive moisture, fine particle size, or excessively thick material layer). Improving permeability should be achieved by thinning the material layer. If the problem is due to the properties of the mixture and reducing the material layer is ineffective, the machine speed can be reduced to decrease airflow requirements. If the negative pressure drops abnormally, it indicates excessive permeability or air leakage. If this is caused by an excessively thin material layer, the process can be stabilized by thickening the material layer. If improved permeability is the primary cause, increasing the machine speed can be attempted to increase production.

[0030] 3. Principle of coordinated adjustment:

[0031] The material layer and machine speed are usually adjusted in opposite directions: thickening the material layer often requires slowing down to maintain the endpoint, while thinning the material layer can increase the speed.

[0032] Stability First: Adjustments should be made in small, gradual steps. During the adjustment period, close attention should be paid to parameter changes, and priority should be given to ensuring that the endpoint is stable at a reasonable position.

[0033] Comprehensive judgment: The decision is made by taking into account the shape of the waste temperature curve, the final temperature, the negative pressure, and the properties of the mixture (moisture, particle size, etc.).

[0034] Core objective: By adjusting the machine speed (controlling sintering time) and the material layer (affecting permeability, heat storage, and sintering time), the sintering endpoint is stabilized at the last 1-2 bellows, with a suitable temperature, ensuring the quality of sintered ore and production efficiency.

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] This invention replaces a portion of the high-silica coarse ore with CSN lump ore undersize powder containing no less than 55% TFe, no less than 14.6% SiO2, and less than 4.3% loss on ignition. By controlling the proportion and moisture content of the CSN lump ore undersize powder, the chemical composition of the iron-containing blended ore for sintering is controlled to reach a specific target range. Simultaneously, by stabilizing the moisture content and average particle size of the iron-containing blended ore for sintering, and controlling SiO2 to no less than 5.4%, this invention reduces the impact of particle size on the non-uniformity of the composition, enhances the agglomeration performance during sintering, reduces the amount of low-melting-point substances generated, and increases the amount of liquid phase generated during sintering, allowing the liquid phase to fully solidify. This promotes further improvement in the final sintering yield and the physicochemical and metallurgical properties of the sintered ore, while significantly reducing the cost of ore blending. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In a first aspect, the present invention provides a sintering iron-containing blended ore for which CSN lump ore undersize powder can replace part of the high-silica coarse powder, comprising the following raw materials by mass percentage: PB powder 11%-17%, BRBF powder 10%-19%, FMG mixed powder 14%-17%, high-silica coarse powder 1%-8%, CSN lump ore undersize powder 2%-6%, blast furnace return ore 14%-16%, Silk Road powder 10%-14%, direct-supply iron concentrate 5%-9%, domestic iron concentrate 3%-5%, Daye low-grade concentrate 1%-2%, lump ore return powder 2%-6%, and secondary resources 3%-5%;

[0039] The chemical composition of the iron-containing homogenized ore for sintering, by mass percentage, includes: TFe: 59.15%±0.3%, SiO2: 5.45%±0.2%, CaO: 2.3%±0.15%, S: 0.14%±0.05%, Al2O3: 2.12%±0.2%, and moisture: 7.9%±0.6%.

[0040] In some examples, the secondary resources include, but are not limited to, at least one of the following: ironmaking gas ash, iron oxide scale, dust collector ash, sludge, steel slag magnetic separation powder, and steel slag tailings.

[0041] Secondly, the present invention provides a CSN lump ore undersize powder to replace part of the high-silica coarse sinter. The raw materials include, by mass percentage: 81%-83% of the iron-containing blended ore for sintering, 13.6%-14% of flux and 4.4%-4.8% of solid fuel.

[0042] In some examples, the chemical composition of the sinter, by mass percentage, includes: TFe: 54.3%-55.0%, FeO: 7.7%-9.7%, SiO2: 5.9%-6.1%, CaO: 11.3%-11.6%, MgO: 1.9%-2.0%, Al2O3: 2.3%-2.4%, S≤0.035%, and basicity of 1.88-1.92.

[0043] In some examples, the flux comprises quicklime, limestone, and dolomite in a mass ratio of (5.8%-6%):(2.0%-2.2%):5.8%; the solid fuel comprises pulverized coal and coke powder in a mass ratio of (2.2%-2.4%):(2.2%-2.4%); the raw materials for the sinter also include recycled ore, the amount of which is 18% of the total mass of the blended ore, flux, and solid fuel (i.e., 18% recycled ore is added externally).

[0044] Thirdly, the present invention provides a method for preparing the CSN lump ore undersize powder to replace part of the high-silica coarse sinter, comprising the following steps:

[0045] (1) Prepare the ingredients according to the raw material ratio;

[0046] (2) The raw materials are mixed with water and granulated to obtain sintered material; wherein the mixing includes primary mixing and secondary mixing. In order to improve the mixing and granulation effect and increase the pelletizing rate of the mixture, the present invention has taken the following measures: a. Water is sprayed on the conveyor belt in front of the primary mixer to pre-digest quicklime, increase its digestion time, and reduce the destructive effect of its digestion and water absorption in the mixer on the pellets; b. The internal liner of the secondary mixer is modified from the conventional liner to the counter-current spiral liner, which extends the granulation time by 2-3 minutes. After testing, the pelletizing rate is increased by 3%-5%, which is a significant effect.

[0047] (3) To maintain a "dynamic balance" system for sinter quality and output production while ensuring stable operation of the blast furnace, this invention employs a 260 m 2The sintering process is carried out using a belt-type exhaust sintering machine. Compared with the previous sintering process, the present invention increases the material layer thickness from 810 mm to 840 mm, increases the ignition temperature from 1000±50℃ to 1100±50℃, the ignition time is 50-70 s, and the holding time is 1-2 min; the vertical firing speed of the sintering machine is reduced from 23 mm / min to 16 mm / min, and the machine speed is reduced from 1.95 m / min to 1.85 m / min; the final sintering temperature is increased from 330±30℃ to 370±30℃.

[0048] (4) Cooling to obtain CSN block ore undersize powder to replace part of the high-silica coarse sinter.

[0049] In the following specific embodiments, the flux meets the following conditions: (1) the proportion of limestone with a particle size <3 mm is not less than 90%, and the moisture content is ≤5%; (2) the proportion of quicklime with a particle size <3 mm is not less than 90%, CaO ≥83%, and activity ≥220; (3) the proportion of dolomite with a particle size <3 mm is not less than 90%, and the moisture content is ≤5%. Dolomite and limestone are transported to the batching tank by belt conveyor, and quicklime is directly sent to the batching tank by sealed tank truck and then compressed into the ore bin by compressed air through pipeline. The solid fuel meets the following conditions: the solid fuel particle size is <25 mm; the moisture content of the white coal is <10%. After the solid fuel is crushed, the proportion of coke powder with a particle size less than 3 mm is 67%-77%, and the proportion of white coal with a particle size less than 3 mm is 63%-73%.

[0050] The mineral powder data used in the following specific embodiments are shown in Table 1.

[0051] Table 1: Mineral Powder Data

[0052]

[0053] Example 1

[0054] A method for preparing CSN lump ore undersize powder to replace part of the high-silica coarse sinter includes the following steps:

[0055] S1, Ingredients

[0056] To ensure accurate batching, the blended ore, flux, fuel, and return ore are automatically batched according to pre-set ratios using a quantitative feeding device, with the feeding rate automatically controlled by a computer. To stabilize the material level in the batching troughs and ensure a constant material feed rate, each trough is equipped with a weighing level gauge that can continuously display the measured values ​​online. The raw materials for the blended ore are as follows: PB powder 14%, BRBF powder 10%-19%, FMG mixed powder 16%, high-silica coarse powder 1%-8%, CSN lump ore undersize powder 2%-6%, blast furnace return ore 15%, Silk Road powder 12%, direct-supply iron concentrate 7%, domestic iron concentrate 4%, Daye low-grade concentrate 1.5%, lump ore return powder 3%, and secondary resources 4.5%. Specifically, the secondary resources are ironmaking gas ash 0.6%, iron oxide scale 0.8%, dust collector ash 1.5%, sludge 0.2%, steel slag magnetic separation powder 1%, and steel slag tailings 0.4%.

[0057] The batching sequence in this embodiment is: mixed ore → fuel → limestone → dolomite → quicklime → return ore.

[0058] S2, Mixing and Granulation

[0059] To enhance the mixing and granulation of the mixture and improve its permeability, this embodiment employs a cylindrical mixer for two-stage mixing. The first stage involves adding water for wetting and mixing to ensure uniform distribution of the components and particle size in the mixture. The second stage primarily aims at granulation. During granulation, a small amount of water is added for wetting, and steam is used to increase the material temperature, thereby improving the permeability and sintering effect in the subsequent sintering process.

[0060] To improve the mixing and granulation effect and increase the pelletizing rate of the mixture, the following measures were taken in this embodiment: a. Water was sprayed on the conveyor belt in front of the primary mixer to pre-digest the quicklime, increase its digestion time, and reduce the destructive effect of water absorption during digestion in the mixer on the pellets; b. The internal liner of the secondary mixer was modified from the conventional liner to a counter-current spiral liner, extending the granulation time by 2-3 minutes. After testing, the pelletizing rate increased by 3%-5%, which was a significant effect.

[0061] Specifically, in this embodiment, the water content of the first mixture is 90%, and the filling rate is 10%-16%; the water content of the second mixture is 10%, and the filling rate is 9%-15%, with a total mixing and granulation time of 5-9 min.

[0062] S3, sintering

[0063] (1) Laying the base material

[0064] This embodiment adopts a bottom-laying process to protect the trolley grate bars, ensure thorough burning of the material layer, reduce dust content in the flue gas, and extend the service life of the trolley. The particle size of the bottom-laying material is 10-20 mm, and the thickness of the bottom-laying material layer is 50-60 mm, before the material is spread.

[0065] (2) Fabric

[0066] To achieve uniform material distribution and reasonable particle size distribution, this embodiment uses a shuttle feeder to uniformly feed the material into the mixing trough of the sintering machine, and then uses a round roller feeder and a nine-roller feeder to uniformly distribute the material on the trolley with the bottom material laid on it. The particle size of the raw material segregates from top to bottom and gradually increases, thereby improving the permeability of the material layer and improving the quality and yield of the sinter. The thickness of the material layer is controlled at 840 mm.

[0067] (3) Ignition

[0068] The sintering ignition process uses mixed coal gas as the main fuel, with a calorific value of 9211 kJ·m³. -3 This embodiment uses thick-layer sintering technology with an ignition temperature of 1100±50℃. To reduce the negative impact on the quality of the sinter caused by the rapid drop in the surface sinter temperature, the ignition time is about 1 minute and the holding time is 1~2 minutes.

[0069] (4) Sintering

[0070] The sintering machine used in this embodiment is a 260 m³ / h sintering machine. 2 The belt-type exhaust sintering machine has a trolley width of 4 m and an effective exhaust length of 67 m. After the mixture on the sintering machine is ignited, it is subjected to exhaust sintering. The sintering process proceeds from top to bottom and continues until the end of the sintering process. The vertical firing speed of the sintering machine is 16 mm / min, and the machine speed is 1.85 m / min. The temperature at the end of the sintering process is controlled at 370±30℃. Finally, the mixture is sintered into a sintered cake and unloaded at the tail end of the machine. It then enters the cooler through the feed chute, single-roll crusher, and feed chute.

[0071] S4, Cooling

[0072] The temperature of the sinter after single-roll crushing is still relatively high, which will cause significant damage to the equipment in subsequent processes and increase the difficulty of product transportation and plant layout. Therefore, a cold ore process is adopted, which is to cool the sinter after hot crushing.

[0073] The cooling methods for sintered ore are mainly divided into exhaust cooling and forced air cooling. Forced air cooling is suitable for thick material layer sintering, so this implementation adopts forced air ring cooling.

[0074] S5. Granulation System and Finished Ore Storage

[0075] To ensure the quality of the bottom material and produce sinter with low powder content and uniform particle size to meet the requirements of blast furnace smelting, this embodiment adopts a one-crusher-three-screen process and selects a two-use-one-standby granulation system. The 20~10 mm particle size product from the screening product is selected as the bottom material, and the sinter powder with a return ore particle size <5 mm and the sinter powder in the dust removal are transported to the batching room to participate in the batching. The finished sinter is first stored in the finished product warehouse and then transferred to the blast furnace for use.

[0076] Five sets of experiments were designed in this embodiment, and the specific data of the five sets of experiments are shown in Table 2-5.

[0077] Table 2: Ingredients and composition of the blended ore in each experimental group

[0078]

[0079] As shown in Table 2, compared with the original ore blending scheme (Group 1), the present invention uses CSN lump ore undersize powder to replace part of the high-silica coarse powder, which can save up to 46.85 yuan per ton of ore blending cost.

[0080] Table 3: Raw material ratio of sinter for each test group

[0081]

[0082] Table 4: Chemical composition of sinter in each experimental group

[0083]

[0084] Table 5: Quality of sinter in each test group

[0085]

[0086] Comparative Example 1

[0087] The sintered ore in this comparative example is basically the same as group 4 in Example 1, except that the improved sintering scheme is used. Specifically, during sintering, the material layer thickness is 810 mm, the ignition temperature is 1000±50℃, the vertical sintering speed of the sintering machine is 23 mm / min, the machine speed is 1.95 m / min, and the final sintering temperature is 330±30℃. The quality of the sintered ore in this comparative example is as follows:

[0088]

[0089] In summary, this invention replaces a portion of the high-silica coarse ore with CSN lump ore undersize powder containing no less than 55% TFe, no less than 14.6% SiO2, and a burn loss of no more than 4.3%. By controlling the proportion and moisture content of the CSN lump ore undersize powder, the chemical composition of the iron-containing blended ore for sintering is controlled to reach a specific target range. Simultaneously, by stabilizing the moisture content and average particle size of the iron-containing blended ore for sintering, and controlling SiO2 to no less than 5.4%, this invention reduces the impact of particle size on compositional inhomogeneity, enhances the agglomeration performance and the generation of low-melting-point substances during sintering, increases the amount of liquid phase generated during sintering, and ensures sufficient solidification of the liquid phase. This promotes further improvement in the final sintering yield and the physicochemical and metallurgical properties of the sintered ore, while significantly reducing the cost of ore blending.

[0090] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for replacing a portion of high-silica coarse iron-containing blended ore for sintering with CSN lump ore undersize powder, characterized in that, By weight percentage, it includes the following raw materials: PB powder 11%-17%, BRBF powder 10%-19%, FMG mixed powder 14%-17%, high-silica coarse powder 1%-8%, CSN lump ore undersize powder 2%-6%, blast furnace return ore 14%-16%, Silk Road powder 10%-14%, direct supply iron concentrate 5%-9%, domestic iron concentrate 3%-5%, Daye low-grade concentrate 1%-2%, lump ore return powder 2%-6%, secondary resources 3%-5%; The chemical composition of the iron-containing homogenized ore for sintering, by mass percentage, includes: TFe: 59.15%±0.3%, SiO2: 5.45%±0.2%, CaO: 2.3%±0.15%, S: 0.14%±0.05%, Al2O3: 2.12%±0.2%, and moisture: 7.9%±0.6%.

2. A method for replacing part of the high-silica coarse sinter with CSN lump ore undersize powder, characterized in that, The raw materials, by mass percentage, include: 81%-83% of the iron-containing blended ore for sintering as described in claim 1, 13.6%-14% of flux, and 4.4%-4.8% of solid fuel.

3. The CSN lump ore undersize powder used to replace part of the high-silica coarse sinter as described in claim 2, characterized in that, The chemical composition of the sinter, by mass percentage, includes: TFe: 54.3%-55.0%, FeO: 7.7%-9.7%, SiO2: 5.9%-6.1%, CaO: 11.3%-11.6%, MgO: 1.9%-2.0%, Al2O3: 2.3%-2.4%, S≤0.035%, and basicity of 1.88-1.

92.

4. The CSN lump ore undersize powder used to replace part of the high-silica coarse sinter as described in claim 2, characterized in that, The flux comprises quicklime, limestone and dolomite in a mass ratio of (5.8%-6%):(2.0%-2.2%):5.8%.

5. The CSN lump ore undersize powder used to replace part of the high-silica coarse sinter as described in claim 2, characterized in that, The solid fuel comprises pulverized coal and coke powder in a mass ratio of (2.2%-2.4%):(2.2%-2.4%).

6. The CSN lump ore undersize powder used to replace part of the high-silica coarse sinter as described in claim 2, characterized in that, The raw materials for the sinter also include recycled ore, and the amount of recycled ore is 18% of the total mass of the blended ore, flux and solid fuel.

7. The method for preparing CSN lump ore undersize powder to replace part of the high-silica coarse sinter as described in any one of claims 2-6, characterized in that, Includes the following steps: Prepare the ingredients according to the specified proportions. The raw materials are mixed with water and granulated to obtain sintered material; During the sintering process, the material layer thickness is controlled at 840 mm, the ignition temperature is 1100±50℃, the ignition time is 50-70 s, the holding time is 1-2 min, and the sintering endpoint temperature is controlled at 370±30℃. After cooling, CSN lump ore undersize powder is obtained to replace part of the high-silica coarse sinter.

8. The method for preparing CSN lump ore undersize powder to replace part of the high-silica coarse sinter according to claim 7, characterized in that, During the sintering process, the sintering speed of the sintering machine is 16 mm / min.

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