Sintering method of high-burning-loss siderite and high alkali metal magnetite concentrate

Abstract

The invention discloses a sintering method for high-burning-loss siderite and high alkali metal magnetite concentrate. According to the sintering process, through stable process parameter control such as precise sintering temperature, time and alkalinity regulation and control, it is ensured that the sintering reaction is fully carried out, and the rejection rate and the reworking frequency are reduced. Therefore, not only is the stability of the sintered ore product quality improved, but also the production efficiency is improved. According to the method, the drum strength of the sintered ore under the sintering condition that the high-burning-loss siderite is matched with the high alkali metal magnetite concentrate is improved, the quality of the sintered ore is stabilized, the fuel consumption is reduced, the technical and economic indexes are improved, and the cost of the sintered ore is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sintered ore, and specifically relates to a sintering method for high-loss siderite with high-alkali metal magnetite concentrate. Background Art

[0002] Siderite is widely distributed in nature and is an important iron ore resource. However, it has high burn-loss characteristics, which pose many challenges to traditional sintering processes. During the sintering process, high burn-loss can lead to problems such as poor permeability of the sintering material layer, unstable sintering speed, and large volume changes during sintering, affecting the quality and output of sintered ore. The self-produced ore of Kunming Iron and Steel Company is mainly Dahongshan concentrate, which belongs to magnetite, has a high alkali metal (potassium and sodium) content, a relatively fine particle size, with more than about 60% less than 200 mesh, and the vast majority of mineral particles exist in a monomer state, are relatively dense, have poor balling properties, a narrow softening and melting temperature range, and are relatively difficult to sinter. Since 2024, in order to broaden the ore utilization channels, Kunming Iron and Steel has tried to add 3-10% of siderite to the blended ore. Due to its 25% burn-loss and its use in combination with the relatively difficult-to-sinter Dahongshan concentrate, the following deficiencies exist when using general sintering methods: 1. When the current sintering process treats siderite, due to the poor response to the burn-loss characteristics, it is difficult to achieve an ideal level of strength for the sintered ore, which is not conducive to the subsequent blast furnace ironmaking process. For example, the sintered ore produced by some sintering methods is prone to breakage after being charged into the furnace, affecting the air permeability and smelting efficiency in the blast furnace.

[0003] 2. In terms of energy consumption, when the existing sintering methods treat high-loss siderite, due to inaccurate process control, a large amount of energy is required to maintain the sintering reaction, increasing the production cost and not meeting the environmental protection requirements of energy conservation and emission reduction.

[0004] In view of the above deficiencies, the present invention aims to provide a sintering method for high-loss siderite with high-alkali metal magnetite concentrate. Summary of the Invention

[0005] The object of the present invention is to provide a sintering method for high-loss siderite with high-alkali metal magnetite concentrate.

[0006] The first object of the present invention is achieved as follows. A sintering method for high-loss siderite with high-alkali metal magnetite concentrate is realized according to the following steps: 1) Crush and screen the siderite to a particle size of -5mm ≥80%; mix the crushed and screened siderite with other ores to obtain a blended ore; the blended ore includes the following raw materials in weight ratio: 5-10% of siderite powder, 35-40% of high-alkali metal magnetite concentrate, and 50-60% of other iron powder concentrates; 2) Add coke powder accounting for 3-5% of the total weight of the blended ore to the blended ore, so that the fixed carbon content in the sintering material is 3.4-4.0%, and the FeO content of the sinter is 8.0-9%; then add fluxes accounting for 17-20% of the total weight of the blended ore to obtain a mixed material, so that the basicity R of the mixed material is within the range of 2.15-2.25; 3) Pre-press the mixed material with a pressure of 600-900 kg to make the thickness of the material layer reach 750-850 mm; 4) Control the temperature of the sintering material to reach 47-50 °C, and control the moisture in the mixed material at 7.0-7.5%; control the rotation speed of the nine-rolls at 600-800 revolutions / min, control the speed of the sintering machine at 0.9-1.0 m / min, the ignition temperature is 1200 °C - 1300 °C, control the temperature at the end of the sintering machine at 380-450 °C, and control the exhaust gas temperature at the tail of the sintering machine at 120-150 °C; 5) After sintering, size and screen to obtain sinter, and the FeO content in the sinter is 8.0-9.0%, and the basicity is 2.15-2.25.

[0007] The beneficial effects of the present invention are as follows: 1. The sintering process of the present invention controls through stable process parameters, such as precise regulation of sintering temperature, time and basicity, to ensure the full progress of the sintering reaction, reduce the rejection rate and rework times. This not only improves the stability of the sinter product quality, but also improves the production efficiency. The method of the present invention improves the drum strength of the sinter under the sintering conditions of high-loss siderite and high-alkali metal magnetite concentrate, stabilizes the sinter quality, reduces fuel consumption, improves technical and economic indicators, and reduces the cost of sinter.

[0008] 2. By adopting the method of the present invention, enterprises can reduce the dependence on expensive iron ore, thereby reducing the raw material procurement cost.

[0009] 3. The sinter prepared by adopting the method of the present invention can improve the production stability and product quality of the blast furnace, reduce the furnace condition fluctuations caused by quality problems, and there is no need to transform the existing equipment. Specific embodiments

[0010] The following further elaborates on the present invention in conjunction with embodiments, but does not limit the present invention in any way. Any transformation or improvement based on the teachings of the present invention falls within the protection scope of the present invention.

[0011] A sintering method for high-loss siderite and high-alkali metal magnetite concentrate of the present invention is realized according to the following steps: 1) Crush and screen the siderite to a particle size of -5mm ≥80%; mix the crushed and screened siderite with other ores to obtain a mixed ore; the mixed ore includes the following raw materials by weight ratio: 5-10% siderite powder, 35-40% high-alkali metal magnetite concentrate, and 50-60% other iron-containing powder concentrates; 2) Add 3-5% of the total weight of the mixed ore of coke powder to the mixed ore, so that the fixed carbon content in the sintering material is 3.4-4.0%, and the FeO content of the sinter is 8.0-9%; then add 17-20% of the total weight of the mixed ore of flux to obtain a mixed material, so that the basicity R of the mixed material is in the range of 2.15-2.25; 3) Pre-press the mixed material with a pressure of 600-900 kg to make the thickness of the material layer reach 750-850 mm; 4) Control the temperature of the mixed material to reach 47-50 °C, and the moisture in the mixed material is controlled at 7.0-7.5%; the speed of the nine rollers is controlled at 600-800 revolutions / min, the speed of the sintering machine is controlled at 0.9-1.0 m / min, the ignition temperature is 1200 °C - 1300 °C, the temperature at the end of the sintering machine is controlled at 380-450 °C, and the exhaust gas temperature at the tail of the sintering machine is controlled at 120-150 °C; 5) After sintering, size and screen to obtain sinter, the FeO content in the sinter is 8.0-9.0%, and the basicity is 2.15-2.25.

[0012] In step 1), the high-alkali metal magnetite concentrate is Dahongshan concentrate.

[0013] In step 1), during the stacking process of the mixed ore, the herringbone stacking method is adopted, and the control range of TFe of the mixed ore is: 62±0.8%, and the control range of basicity R is: 0.2±0.05%, making the mixed ore more uniform.

[0014] In step 4), the sintering machine is a 450m 2 sintering machine.

[0015] In step 5), during the belt transportation of the prepared sinter, calcium chloride solution is sprayed on the finished product belt at a ratio of the feeding amount *(0.3-0.5%), and the low-temperature reduction degradation index ≥60%.

[0016] In step 5), after the sinter is sized and screened, the sinter in the storage bin and transfer bin ensures that there is no less than 1 / 2 of the bin capacity, reducing the number of drops and the drop height, and avoiding crushing during the transfer process Example 1 According to the existing raw materials on the stockyard and the needs of the production plan, 6% siderite powder, 25% Newman powder, 38% Dahongshan concentrate, 6% Tengchong concentrate, 12% 62-mesh concentrate, and 13% 65-mesh concentrate are added to the mixed ore. Flux and fuel are added in the sintering batching room, and the feeding amount of the sintering machine is 450 t / h.

[0017] (1) Key control points during the stacking process of blended ore ① During the stacking process, use a herringbone stacking method to make the blended ore more uniform; ② Control the TFe of the blended ore at 61.8% and the basicity R at 0.22 times.

[0018] (2) Key control points during the sintering process using a 450 m 2 sintering machine ① Control the particle size of siderite -5mm at 85%.

[0019] ② Add coke powder accounting for 3.5% of the total weight of the blended ore to make the fixed carbon content in the sintering material 3.5%, ensure the thickness of the red layer at the tail of the sintering machine and the strength of the sintered ore, and control the FeO of the sintered ore at 8.5%; ③ Add limestone powder accounting for 12% of the total weight of the blended ore, dolomite powder accounting for 5%, and quicklime powder accounting for 2% to make the basicity R of the sintered ore = 2.18; ④ Pre - press the mixed material on the sintering machine (pressure 800 kg) to increase the thickness of the material layer to 820 mm; ⑤ Use steam to heat in two mixing drums to make the temperature of the sintering material reach 48℃; ⑥ Control the moisture content in the mixed material at 7.2%, which is beneficial to the balling of the mixed material and increases the air permeability of the thick material layer; ⑦ To make the fuel distribution more reasonable, control the speed of the nine - roll at 700 revolutions / min; ⑧ The speed of the sintering machine is 0.9 m / min to ensure the uniform and continuous speed of the sintering machine and stabilize the quality of the sintered ore; ⑨ Control the ignition temperature of the sintering machine at 1250℃ and the end - point temperature at 400℃ to ensure that the sintering is complete without raw material phenomenon; ⑩ Control the exhaust gas temperature at the tail of the sintering machine at 130℃ to control fuel consumption and reduce costs.

[0020] (3) Key control points during the belt transportation process of sintered ore ① Spray calcium chloride solution on the finished product belt at a ratio of 0.3% of the feeding amount, and the low - temperature reduction degradation index of the sintered ore is 65%.

[0021] ② After the sintered ore is sized and screened, ensure that 1 / 2 of the bins in the storage bin and transfer bin are filled with sintered ore, reduce the number and height of drops, and avoid crushing during the transfer process.

[0022] In this embodiment, with a 6% siderite material structure, the fuel consumption is only 45.1 kg / t, which is 2.5 kg / t lower than the original technology (mixing ore with 6% siderite powder, 25% Newman powder, 38% Dahongshan concentrate, 6% Tengchong concentrate, 12% 62-matched concentrate, 13% 65-matched concentrate, flux ratio of 10% limestone powder, 5% dolomite powder, 2% quicklime powder, fixed carbon content in the sintering material of 3.6%, sintered ore basicity of 2.1 ± 0.05%, FeO content of 7.5 - 8.0%, mixture temperature of 40 °C, mixture moisture of 7.5%, nine-roll speed of 600 rpm, sintering machine speed of 1.0 m / min, end point temperature controlled at 380 ± 20 °C, exhaust gas temperature of 120 ± 10 °C, and no calcium oxide solution sprayed on the sintered ore); the return ore rate under the blast furnace bunker is reduced by 2%, only 11.3%; the drum index is 81%. Compared with the original technology, the cost of the sintered ore is reduced by 4.5 yuan per ton.

[0023] Example 2 According to the existing raw materials in the stockyard and the requirements of the production plan, 10% siderite powder, 21% Newman powder, 38% Dahongshan concentrate, 6% Tengchong concentrate, 12% 62-matched concentrate, and 13% 65-matched concentrate are added to the mixing ore. Fluxes and fuels are added in the sintering batching room, and the feeding amount of the sintering machine is 450 t / h.

[0024] (1) Control points during the stacking process of the mixing ore ① During the stacking process, the herringbone stacking method is adopted to make the mixing ore more uniform; ② The TFe of the mixing ore is controlled at 61.5%, and the basicity R is controlled at 0.25 times.

[0025] (2) Control points during the sintering process using a 450 m 2 sintering machine ① The -5 mm particle size of the siderite is controlled at 85%.

[0026] ② 4% of the total weight of the coke powder is added to the mixing ore to make the fixed carbon content in the sintering material 3.8%, ensuring the thickness of the red layer at the tail of the sintering machine and the strength of the sintered ore, and controlling the FeO of the sintered ore at 8.8%; ③ 13% of the total weight of the limestone powder, 5% of the dolomite powder, and 2% of the quicklime powder are added to the mixing ore to make the basicity R of the sintered ore = 2.20 times; ④ The mixture on the sintering machine is pre-pressed (pressure 900 kg) to increase the thickness of the material layer to 840 mm; ⑤ Steam is used to heat in two mixing barrels to make the temperature of the sintering material reach 50 °C; ⑥ The moisture in the mixture is controlled at 7.3%, which is beneficial to the balling of the mixture and increases the air permeability of the thick material layer; ⑦ In order to make the fuel distribution more reasonable, the nine-roll speed is controlled at 700 rpm; ⑧ The machine speed of the sintering machine is 0.9 m / min to ensure the uniform and continuous speed of the sintering machine and the quality of the sintered ore is stable. ⑨ The ignition temperature of the sintering machine is controlled at 1260 °C, and the end point temperature is controlled at 420 °C to ensure that the sintering is complete and no raw material phenomenon occurs. ⑩ The exhaust gas temperature at the tail of the sintering machine is controlled at 140 °C to control fuel consumption and reduce costs.

[0027] (3) Control key points during the belt transportation of sintered ore ① Spray calcium chloride solution on the finished product belt at a ratio of 0.5% of the feeding amount, and the low-temperature reduction degradation index of the sintered ore is 65%.

[0028] ② After the sintered ore is sized and screened, ensure that 1 / 2 of the bins in the storage bin and transfer bin are filled with sintered ore, reduce the number of drops and the drop height, and avoid crushing during the transfer process.

[0029] In this embodiment, under the condition of a 10% siderite material structure, the fuel consumption is only 45.3 kg / t, which is 2.3 kg / t lower than the original technology (in the blended ore, 6% siderite powder, 25% Newman powder, 38% Dahongshan concentrate, 6% Tengchong concentrate, 12% 62-mesh concentrate, 13% 65-mesh concentrate, the flux ratio is 10% limestone powder, 5% dolomite powder, 2% quicklime powder, the fixed carbon content in the sintering material is 3.6%, the sintered ore basicity is 2.1 ± 0.05%, the FeO content is 7.5 - 8.0%, the temperature of the mixed material is 40 °C, the moisture content of the mixed material is 7.5%, the nine-roll rotates at 600 r / min, the machine speed of the sintering machine is 1.0 m / min, the end point temperature is controlled at 380 ± 20 °C, the exhaust gas temperature is 120 ± 10 °C, and no calcium oxide solution is sprayed on the sintered ore); the return ore rate under the blast furnace trough is reduced by 1.8%, only 11.5%; the drum index is 80.6%. The cost of the sintered ore is reduced by 4.1 yuan / ton compared with the original technology.

Claims

1. A sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate, characterized in that: To do this, follow these steps: 1) Crushing and screening the siderite to a particle size of -5mm ≥80%; mixing the crushed and screened siderite with other ores to obtain a mixed ore; the mixed ore includes the following raw materials in weight ratio: 5-10% siderite powder, 35-40% high alkali metal magnetite concentrate, and 50-60% other iron-containing powder concentrate; 2) Add 3-5% coke powder to the mixed ore, so that the fixed carbon content in the sintered material is 3.4-4.0%, and the FeO content of the sintered ore is 8.0-9%; then add 17-20% flux to the total weight of the mixed ore to obtain a mixed material, so that the basicity R of the mixed material is in the range of 2.15-2.25; 3) Pre-press the mixture with a pressure of 600-900kg to make the material layer thickness reach 750-850mm; 4) Control the temperature of the mixture to 47-50℃, and the moisture content of the mixture to 7.0-7.5%; the speed of the nine rollers is controlled at 600-800 rpm, the speed of the sintering machine is controlled at 0.9-1.0 m / min, the ignition temperature is 1200℃-1300℃, the terminal temperature of the sintering machine is controlled at 380-450℃, and the exhaust gas temperature of the sintering machine is controlled at 120-150℃; 5) After sintering, the ore is sized and sieved to obtain sintered ore, in which the FeO content is 8.0-9.0% and the basicity is 2.15-2.

25.

2. The sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate according to claim 1, characterized in that: In step 1), the high alkali metal magnetite concentrate is Dahongshan concentrate.

3. The sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate according to claim 1, characterized in that: In step 1), herringbone stacking is adopted in the process of mixing the ore, the control range of TFe of the mixed ore is: 62±0.8%, and the control range of alkalinity R is: 0.2±0.05%, so that the mixed ore is more uniform.

4. The sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate according to claim 1, characterized in that: In step 4), the sintering machine is 450m 2 Sintering machine.

5. The sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate according to claim 1, characterized in that: In step 5), during the belt transportation of the prepared sintered ore, a calcium chloride solution is sprayed on the finished product belt at a ratio of feed amount × (0.3-0.5%), and the low-temperature reduction pulverization index is ≥ 60%.

6. The sintering method of high-burning-loss siderite with high-alkali metal magnetite concentrate according to claim 1, characterized in that: In step 5), after the sintered ore is screened, the sintered ore in the storage bin and the transfer bin is guaranteed to have a bin space of not less than 1 / 2, so as to reduce the number of drops and the height of the drops and avoid crushing during the transportation process.