Method and apparatus for improving sinter quality

Abstract

This invention discloses a method and apparatus for improving the quality of sintered ore, belonging to the field of sintered ore technology. The method includes: weighing and batching iron ore powder, flux, and fuel according to the target basicity and MgO content of the sintered ore to obtain sintering raw materials; adding water to the sintering raw materials to form pellets, and then distributing the pellets onto the surface of the sintering machine trolley; igniting and sintering the sintering machine trolley with the distributed materials; using an air heater for exhaust sintering; and cooling, screening, and granulation after sintering to obtain sintered ore. The apparatus of this invention includes: a cold air blower, an air heater, a flow regulating valve, a hot air guide hood, a sintering machine trolley, and an exhaust system. Applying the method and apparatus of this invention can improve the sintered ore drum index, significantly reduce the internal return rate and solid fuel consumption, and comprehensively achieve the effects of quality improvement and energy saving.

Description

Technical Field

[0001] This invention relates to the field of sinter production technology, specifically to a method and apparatus for improving the quality of sinter. Background Technology

[0002] Sinter is a primary raw material for blast furnace ironmaking, and its yield and quality directly impact the technical and economic indicators of subsequent ironmaking processes. Currently, the mainstream process for producing sinter in domestic and international enterprises is pyrometallurgical blast sintering. However, traditional blast sintering processes have inherent technical flaws. During sintering, ambient temperature air (cold air) is continuously drawn in, initially contacting the already sintered, high-temperature surface layer of sinter, causing rapid cooling in that area within a very short time. From a microscopic perspective, this rapid cooling generates significant thermal stress within the silicate binder phase of the sinter, leading to embrittlement of its microstructure and the formation of microcracks. This microscopic damage manifests macroscopically as a significant decrease in the strength of the surface sinter, resulting in a brittle texture. Sinter with insufficient strength is prone to powder formation during subsequent crushing, screening, transportation, and furnace loading, leading to a reduced yield. This powder is screened out during the granulation process as return ore, which must be returned to the batching system for re-sintering. This not only increases the return rate and reduces effective output, but also consumes additional solid fuel due to the repeated sintering of the returned ore, directly leading to an increase in solid fuel consumption in the process and a huge waste of energy.

[0003] Therefore, how to slow down or eliminate the rapid cooling effect of surface sintered ore has been a technical problem that has long been in the hands of those skilled in the art. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, the present invention aims to provide a method for improving the quality of sintered ore, which can improve the quality of sintered ore and reduce solid fuel consumption. The method specifically includes the following steps: (1) Weigh and batch iron ore powder, flux and fuel according to the target basicity (CaO / SiO2) and MgO content of sinter to obtain sintering raw materials; add water to the sintering raw materials to form pellets (water content is 8.0±0.2%) and then spread the materials onto the surface of the sintering machine trolley.

[0005] (2) Ignite and sinter the sintering machine trolley with the material loaded.

[0006] (3) Use an air heater to perform sintering; after sintering, cool and screen the granules to obtain sintered ore.

[0007] Preferably, in step (1) of the present invention, the target alkalinity is 1.90-2.40 times; the mass percentage of MgO in the sintering raw material is 2.6%-3.1%; and the thickness of the fabric layer is 800mm-880mm.

[0008] The flux and fuel used in this invention are conventional fluxes and fuels; preferably, the flux in step (1) of this invention is quicklime, limestone and dolomite, and the fuel is coke under blast furnace screen.

[0009] Preferably, the conditions for ignition sintering in step (2) of the present invention are: sintering machine speed of 0.95-1.45m / min, ignition temperature of 1130-1180℃, and ignition time of 3-5min.

[0010] Preferably, the conditions for exhaust sintering in step (3) of the present invention are: heating temperature of 360℃-400℃ and air pressure of 6kPa-9kPa.

[0011] Another object of the present invention is to provide an apparatus for a method of improving the quality of sintered ore, the method of improving the quality of sintered ore being implemented by means of the following apparatus: a cold air blower 1, an air heater 4, a flow regulating valve 6, a hot air guide hood 8, a sintering machine trolley 9, and an exhaust system.

[0012] Preferably, the outlet of the cold air blower 1 is connected to the inlet of the air heater 4 through a cold air pipe 2; the outlet of the air heater is connected to the air inlet of the hot air guide shroud through a hot air pipe 7, and a flow regulating valve 6 is provided on the hot air pipe 7; the air outlet of the hot air guide shroud 8 faces upwards towards the sintering machine trolley 9 and covers the entire material surface of the sintering machine trolley; the exhaust system is located below the sintering machine trolley 9, and the exhaust port of the exhaust system is connected to the air box 11 at the bottom of the sintering machine trolley to form a negative pressure at the bottom of the material layer and guide hot air to penetrate the material layer.

[0013] Preferably, the air heater of the present invention adopts a double-shell structure; the inner layer of the double-shell structure is made of high-temperature resistant material, and multiple sets of high-temperature resistant Cr25Ni20 alloy heating rods 3 are built in a matrix uniform arrangement to ensure full coverage of the heating area; multiple spiral guide plates 5 are set inside, which can effectively extend the residence time of cold air in the heater, ensure sufficient and stable heat exchange, and the hot air can also introduce some heat for sintering.

[0014] Preferably, the hot air guide hood 8 of the present invention adopts a streamlined design with an inlet diameter of 500mm and an outlet with a wide and flat structure (width 5000mm, height 2000mm), which is compatible with the width of the sintering machine trolley; the hot air guide hood 8 is equipped with a honeycomb flow equalization plate 10 with a hole diameter of 15mm to ensure that the hot air is evenly diffused to the surface of the sintering material layer; the bottom of the hot air guide hood 8 is bolted to make the height between it and the surface of the sintering material adjustable, with an adjustable height range of 50-100mm, to ensure the hot air delivery efficiency.

[0015] Preferably, the exhaust system of the present invention is located below the sintering machine trolley 8, the air box 11 is connected to the main flue 13 through the air duct 12, and the main flue is connected to the main exhaust fan 14.

[0016] Preferably, the device of the present invention can be equipped with an intelligent PID temperature controller and a pressure transmitter, with a temperature control accuracy of ±5℃ and a pressure control accuracy of ±0.2kPa; the temperature sensor (PT100) collects the hot air temperature at the outlet of the air heater 4 in real time, feeds it back to the controller and compares it with the set value 0, and achieves precise closed-loop temperature control by adjusting the power supply voltage (0-380V) of the heating rod 3; the pressure transmitter is installed at the outlet of the hot air pipe 7 to monitor the air pressure in real time, and automatically adjusts the valve opening through the electric flow regulating valve 6 (adjustment range 0-100%) to control the hot air output pressure to be stable within the set range.

[0017] This invention provides a method and apparatus for improving the quality of sintered ore, which has the following beneficial effects: This invention, through the synergistic effect of process and equipment, can generate hot air with highly stable temperature and pressure. A hot air guide hood covering the entire material surface is used to uniformly guide the hot air to the surface of the sintering layer for exhaust sintering. On the one hand, this invention significantly slows down the rapid cooling rate of the material layer surface, effectively preventing embrittlement and pulverization of the sinter, greatly improving the yield and strength of the sinter, and enhancing various physical properties. On the other hand, the introduction of physical heat optimizes the heat distribution of the material layer, significantly reducing solid fuel consumption while ensuring quality. Furthermore, the stable hot air supply and uniform guide design eliminate edge effects on the material surface, ensuring the uniformity and stability of the sintering process, achieving a comprehensive effect of improving quality and reducing consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system device for improving the quality of sintered ore according to the present invention.

[0019] Figure 2 This is a schematic diagram of the exhaust device of the present invention.

[0020] Figure 1 In the middle: 1-Cold air induced draft fan; 2-Cold air pipe; 3-Heating rod; 4-Air heater; 5-Baffle plate; 6-Flow regulating valve; 7-Hot air pipe; 8-Hot air guide hood; 9-Sintering machine trolley; 10-Honeycomb flow equalization plate.

[0021] Figure 2 In the middle: 9-Sintering machine trolley; 11-Blowbox; 12-Air duct; 13-Main flue; 14-Main exhaust fan. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0023] The method for improving the quality of sintered ore in this embodiment of the invention is carried out in the following apparatus (see schematic diagram of the apparatus as shown). Figure 1 and Figure 2 As shown), after the sintering material is fed, the trolley carrying the material is moved to the sintering furnace for ignition and sintering. After ignition, exhaust sintering is performed. The specific process is as follows: the cold air blower 1 is turned on, and the ambient cold air (temperature 10-25℃) is delivered to the air heater 4 through the cold air pipe 2. The air heater adopts a double-shell structure, the outer layer is galvanized sheet, and the inner layer is made of high-temperature resistant 310L stainless steel. It has 9 sets of high-temperature resistant Cr25Ni20 alloy heating rods 3, each with a heating power of 5kW and a total heating power of 45kW. The heating rods are arranged in a matrix to ensure full coverage of the heating area. The interior is equipped with 4 layers of spiral guide tubes. The air guide plates 5 are arranged at intervals. The tops of the first and third groups of air guide plates are connected to the air heater 4, and the bottoms of the second and fourth groups of air guide plates are connected to the air heater 4. This effectively prolongs the residence time of cold air in the heater, ensuring sufficient and stable heat exchange. The heating rods generate heat when energized. After entering the air heater 4, the cold air is guided by the air guide plates and flows in an "S" shape along the heating rod matrix area, fully exchanging heat with the heating rods and raising its temperature. After the temperature and pressure are regulated by the intelligent PID control system, the hot air is delivered to the hot air guide hood 8 through the hot air pipe 7 (the hot air guide hood 8 adopts a streamlined design and has a honeycomb-type flow equalization plate 10 inside, such as...). Figure 2 As shown, after being evenly distributed by the flow equalization plate 10, the material is precisely blown onto the sintering material layer on the surface of the sintering machine trolley 9. The exhaust system is located below the sintering machine trolley, and the exhaust port of the exhaust system is connected to the air box 11 at the bottom of the sintering machine trolley 9. A negative pressure is formed at the bottom of the material layer to guide the hot air through the material layer and realize hot air exhaust sintering. The air box 11 of the exhaust system is connected to the main flue 13 through the air duct 12, and the main flue is connected to the main exhaust fan 14.

[0024] Example 1 In this embodiment, the composition and content (by mass percentage) of the sintering raw materials are as follows: 80.30% iron ore powder (of which the mass ratio of concentrate to fine ore is 3:2), 8.90% dolomite, 1.90% limestone, 6.00% quicklime, and 2.90% fuel (coke dust under the blast furnace screen).

[0025] A method for improving the quality of sintered ore, comprising the following specific steps: (1) Based on the target basicity of the sinter (1.90 times) and the MgO content (mass percentage of 2.6%), iron ore powder, dolomite, limestone, quicklime and fuel (coke dust under blast furnace screen) are weighed and batched to obtain sintering raw materials; after adding water to form pellets, the sintering raw materials are spread onto the surface of the sintering machine trolley with a layer thickness of 800 mm.

[0026] (2) Move the sintering machine trolley with the material loaded to the sintering ignition furnace for ignition and sintering (ignition temperature is 1130℃, ignition time is 5min).

[0027] (3) Control the sintering machine speed to 0.95 m / min to ensure uniform and continuous speed; then turn on the air heater to heat the air to 360°C and perform sintering under an air pressure of 9 kPa; after sintering, cool and screen the granules to obtain the finished sintered ore.

[0028] Example 2 In this embodiment, the composition and content (by mass percentage) of the sintering raw materials are as follows: 78.75% iron ore powder (of which the mass ratio of concentrate to fine ore is 3:2), 9.75% dolomite, 1.60% limestone, 7.00% quicklime, and 3.00% fuel (coke dust under blast furnace screen).

[0029] A method for improving the quality of sintered ore, comprising the following specific steps: (1) Based on the target basicity of the sinter (2.10 times) and the MgO content (mass percentage of 2.8%), iron ore powder, dolomite, limestone, quicklime and fuel (coke dust under blast furnace screen) are weighed and batched to obtain sintering raw materials; after adding water to form pellets, the sintering raw materials are spread onto the surface of the sintering machine trolley with a layer thickness of 840 mm.

[0030] (2) Move the sintering machine trolley with the material loaded to the sintering ignition furnace for ignition and sintering (ignition temperature is 1150℃, ignition time is 4min).

[0031] (3) Control the speed of the sintering machine to 1.15 m / min to ensure uniform and continuous speed; then turn on the air heater to heat the air to 380°C and perform sintering under an air pressure of 8 kPa; after sintering, cool and screen the granules to obtain the finished sintered ore.

[0032] Example 3 In this embodiment, the composition and content (by mass percentage) of the sintering raw materials are as follows: 75.35% iron ore powder (of which the mass ratio of concentrate to fine ore is 3:2), 11.00% dolomite, 3.45% limestone, 7.00% quicklime, and 3.20% fuel (coke dust under the blast furnace screen).

[0033] A method for improving the quality of sintered ore, comprising the following specific steps: (1) Based on the target basicity of the sinter (2.40 times) and the MgO content (mass percentage of 3.1%), iron ore powder, dolomite, limestone, quicklime and fuel (coke dust under blast furnace screen) are weighed and batched to obtain sintering raw materials; after adding water to form pellets, the sintering raw materials are spread onto the surface of the sintering machine trolley with a layer thickness of 880 mm.

[0034] (2) Move the sintering machine trolley with the material loaded to the sintering ignition furnace for ignition and sintering (ignition temperature is 1180℃, ignition time is 3min).

[0035] (3) Control the sintering machine speed to 1.45 m / min to ensure uniform and continuous speed; then turn on the air heater to heat the air to 400°C and perform sintering under an air pressure of 6 kPa; after sintering, cool, screen and granulate to obtain the finished sintered ore.

[0036] Comparative Example 1 The composition and content (by mass percentage) of the sintering raw materials in this comparative example are as follows: 80.9% iron ore powder (of which the mass ratio of concentrate to fine ore is 3:2), 8.5% dolomite, 1.75% limestone, 6% quicklime, and 2.85% fuel (coke dust under blast furnace screen).

[0037] A method for improving the quality of sintered ore, comprising the following specific steps: (1) Based on the target basicity of the sinter (1.85 times) and the MgO content (mass percentage of 2.2%), the iron ore powder, dolomite, limestone, quicklime and fuel (coke dust under the blast furnace screen) are weighed and batched to obtain the sintering raw materials; after adding water to form pellets, the sintering raw materials are spread onto the surface of the sintering machine trolley with a layer thickness of 790 mm.

[0038] (2) Move the sintering machine trolley with the material loaded to the sintering ignition furnace for ignition and sintering (ignition temperature is 1100℃, ignition time is 4min).

[0039] (3) Control the sintering machine speed to 1.25 m / min to ensure uniform and continuous speed; after sintering, cool and screen the granules to obtain the finished sintered ore.

[0040] Comparative Example 2 The composition and content (by mass percentage) of the sintering raw materials in this comparative example are as follows: 74.85% iron ore powder (of which the mass ratio of concentrate to fine ore is 3:2), 11.4% dolomite, 3.55% limestone, 7.00% quicklime, and 3.2% fuel (coke dust under blast furnace screen).

[0041] A method for improving the quality of sintered ore, comprising the following specific steps: (1) Based on the target basicity of the sinter (2.45 times) and the MgO content (mass percentage of 3.2%), iron ore powder, dolomite, limestone, quicklime and fuel (coke dust under blast furnace screen) are weighed and batched to obtain sintering raw materials; after adding water to form pellets, the sintering raw materials are spread onto the surface of the sintering machine trolley with a layer thickness of 890 mm.

[0042] (2) Move the sintering machine trolley with the material loaded to the sintering ignition furnace for ignition and sintering (ignition temperature is 1200℃, ignition time is 5min).

[0043] (3) Control the speed of the sintering machine to 1.05 m / min to ensure that the speed is uniform and continuous; after sintering, cool and screen the granules to obtain the finished sintered ore.

[0044] The comparison of sinter quality between Example 1 and Comparative Example 1 of the present invention is shown in Table 1 below.

[0045] Table 1 As shown in Table 1, the quality of sintered ore is significantly improved after using the method and apparatus of this invention for sintering production. The drum index of Examples 1-3 is better than that of Comparative Examples 1-2. Among them, Example 2 reaches 81.46%, which is 1.77% higher than Comparative Example 1 and 1.23% higher than Comparative Example 2. In terms of internal return rate, Examples 1-3 are all lower than Comparative Examples 1-2. Example 2 drops to 17.3%, which is 2.22% lower than Comparative Example 1 and 1.67% lower than Comparative Example 2. In terms of solid fuel consumption, Examples 1-3 are all lower than Comparative Examples 1-2. Example 2 drops to 48.39 kg / t, which is 2.02 kg / t lower than Comparative Example 1 and 1.17 kg / t lower than Comparative Example 2.

[0046] In summary, this invention effectively mitigates the rapid cooling effect of surface sinter and improves the microstructure strength of sinter through the synergistic effect of the process and equipment. This results in an increase in the drum index while reducing the internal return rate and solid fuel consumption, thus achieving a significant effect of improving quality and reducing consumption.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the quality of sintered ore, characterized in that, Specifically, the following steps are included: (1) According to the target basicity and MgO content of the sinter, the iron ore powder, flux and fuel are weighed and batched to obtain the sintering raw material; the sintering raw material is granulated by adding water and then distributed onto the surface of the sintering machine trolley; (2) Ignite and sinter the sintering machine trolley with the material already placed; (3) Use an air heater for exhaust sintering; After sintering, the ore is cooled, screened, and granulated to obtain sintered ore.

2. The method for improving the quality of sintered ore according to claim 1, characterized in that, The target alkalinity in step (1) is 1.90-2.40 times; the mass percentage of MgO in the sintering raw material is 2.6%-3.1%; and the thickness of the fabric layer is 800mm-880mm.

3. The method for improving the quality of sintered ore according to claim 1, characterized in that, The conditions for ignition sintering in step (2) are: sintering machine speed of 0.95-1.45 m / min, ignition temperature of 1130-1180℃, and ignition time of 3-5 min.

4. The method for improving the quality of sintered ore according to claim 1, characterized in that, The conditions for exhaust sintering in step (3) are: heating temperature of 360℃-400℃ and air pressure of 6kPa-9kPa.

5. The apparatus for the method of improving the quality of sintered ore according to claim 1, characterized in that, The method for improving the quality of sintered ore is implemented by the following device, which includes: a cold air blower (1), an air heater (4), a flow regulating valve (6), a hot air guide hood (8), a sintering machine trolley (9), and an exhaust system.

6. The apparatus for improving the quality of sintered ore according to claim 1, characterized in that, The outlet of the cold air blower (1) is connected to the inlet of the air heater (4) through the cold air pipe (2); the outlet of the air heater is connected to the air inlet of the hot air guide hood through the hot air pipe (7), and a flow regulating valve (6) is provided on the hot air pipe (7); the air outlet of the hot air guide hood (8) faces the top of the sintering machine trolley (9) and covers the entire material surface of the sintering machine trolley; the exhaust system is located below the sintering machine trolley (9), and the exhaust port of the exhaust system is connected to the air box (11) at the bottom of the sintering machine trolley.

7. The apparatus for improving the quality of sintered ore according to claim 5 or 6, characterized in that, The air heater adopts a double-shell structure; the inner layer of the double-shell structure is made of high-temperature resistant material and has multiple sets of Cr25Ni20 alloy heating rods (3) inside, which are arranged in a matrix uniformly; and multiple spiral guide plates (5) are set inside.

8. The apparatus for the method of improving the quality of sintered ore according to claim 5 or 6, characterized in that, The hot air guide hood (8) adopts a streamlined design. A honeycomb flow equalization plate (10) is set inside the guide hood. The bottom of the hot air guide hood (8) is adjusted in height with the surface of the sintered material through a bolt structure. The adjustable height range is 50-100mm.

9. The apparatus for improving the quality of sintered ore according to claim 5 or 6, characterized in that, The exhaust system includes a blower box (11) located below the sintering machine trolley (9), which is connected to the main flue (13) via a duct (12), and the main flue is connected to the main exhaust fan (14).

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