Iron ore pelletizing system and control method thereof

Abstract

The present invention discloses an iron ore pelletizing system and a control method thereof, wherein the pelletizing system includes an iron ore storage tank, a bentonite storage tank, a magnesia powder storage tank, a mixer, a double-screw feeder, a disc pelletizing machine, a raw ball screening machine, a vertical furnace, a pipe chain conveyor and a fan. The control method includes 5 steps from S1 to S5. Advantages: The present invention reduces the humidity of the recycled raw material by drying and crushing the recycled unqualified raw material multiple times, and then mixing it with a well-proportioned material, while improving the uniformity of the humidity and the consistency of the proportion after the two materials are mixed, thereby improving the qualified rate of the iron ore pellets, as well as the uniformity of size and quality, helping to improve the stability of the subsequent smelting process, reduce energy consumption, and save energy.

Description

Technical Field

[0001] The present invention relates to the technical field of iron ore pellet production, in particular to an iron ore pelletizing system and a control method thereof. Background Art

[0002] Iron ore pellets are made by mixing milled iron ore powder, bentonite, magnesia powder and other raw materials to form 5-18mm green balls, which are then roasted and sintered to obtain iron-containing raw materials with good metallurgical properties to meet smelting needs. Currently, the iron ore pelletizing system primarily consists of an iron ore storage tank, a bentonite storage tank, a magnesia powder storage tank, a mixer, a pelletizer, a green ball screening machine, and a vertical furnace. The iron ore is ball-milled into a powder and stored in the iron ore storage tank. Powdered iron ore, bentonite, and magnesia powder are uniformly fed into the mixer through a star-shaped feed valve according to a set ratio (iron ore powder with a 200-mesh sieve pass rate of ≥80% and a batching ratio of 93%-97%, bentonite with a 200-mesh sieve pass rate of ≥95% and a batching ratio of 1%-3%, and magnesia powder with a 200-mesh sieve pass rate of ≥85% and a batching ratio of 1%-5%). The mixture is then conveyed by a belt conveyor to the pelletizer, where it is sprayed with water to form pellets. These pellets are then screened in a green ball screening machine. Qualified pellets are then sent to the vertical furnace for sintering, while unqualified raw materials (a mixture of powder and crushed balls) are recycled. However, the metering error of the star-shaped feed valve is large, making it difficult to accurately control the material ratio. In addition, there are currently two ways to recycle unqualified raw materials. The first is to send the unqualified raw materials to a ball mill for ball milling with iron ore, and then mix them with bentonite to make pellets; the second is to send the unqualified raw materials back to the pelletizer for re-pelleting. However, unqualified raw materials have a higher humidity than other raw materials. The first treatment method can easily cause the powder discharged from the ball mill to be high in humidity. When mixed with other raw materials in the mixer, it will clump, resulting in uneven mixing of the raw materials and affecting the uniformity of the final iron ore pellets. Moreover, the unqualified raw materials are already a mixture of iron ore, bentonite, and magnesia powder. After ball milling with iron ore, the unqualified raw materials are then mixed with bentonite and magnesia powder, which will lead to a decrease in the iron ore powder content, making it difficult to control the composition of the iron ore pellets, further affecting the regulation of the subsequent smelting process. When the second treatment method is used, the broken balls in the unqualified raw materials are directly subjected to secondary pelletizing, which easily produces oversized pellets, resulting in an increase in the amount of unqualified raw materials screened out by the raw ball screening machine, which requires repeated treatment, increasing the load and energy consumption of the disc pelletizing machine and the raw ball screening machine; moreover, the proportion of large-sized pellets in the qualified pellets is too large, affecting the uniformity of the mixing of the pellets with other raw materials and the reaction efficiency during the smelting process. Summary of the Invention

[0003] The first object of the present invention is to provide an iron ore pelletizing system.

[0004] The second object of the present invention is to provide a control method for an iron ore pelletizing system.

[0005] The first object of the present invention is implemented by the following technical scheme: an iron ore pelletizing system, which also includes an iron ore storage tank, a bentonite storage tank, a magnesia powder storage tank, a mixer, a double-screw feeder, a disc pelletizing machine, a raw ball screening machine, a vertical furnace, a pipe chain conveyor and a fan, the outlet of the iron ore storage tank, the outlet of the bentonite storage tank and the outlet of the magnesia powder storage tank are respectively connected with the inlet of the iron ore metering tank, the bentonite metering tank and the magnesia powder metering tank through a dosing pipe, a first control valve is installed on the dosing pipe, the outlets of the iron ore metering tank, the bentonite metering tank and the magnesia powder metering tank are respectively connected with the feed port of the mixer through a feeding pipe, and a fourth control valve is installed on the feeding pipe; the outlet of the mixer is connected with the inlet of the double-screw feeder through a feeding pipe, and a second control valve is installed on the feeding pipe; the outlet of the double-screw feeder is connected with the inlet of the disc pelletizing machine, and the outlet of the disc pelletizing machine is connected with the inlet of the raw ball screening machine. The qualified material outlet of the green ball screening machine is located above the feeding end of the conveyor, and the discharge port of the conveyor is located above the inlet of the distributor of the vertical furnace; the unqualified material outlet of the green ball screening machine is connected with the inlet of the tube chain conveyor, and the outlet of the tube chain conveyor is connected with the inlet of the recovery tank, the exhaust port of the recovery tank is connected with the inlet of the cyclone dust collector, and the ash discharge port of the cyclone dust collector is connected with the inlet of the mixer; the discharge port of the recovery tank is connected with the inlet of the double-screw feeder through a recovery pipe, and a third control valve is installed on the recovery pipe; the exhaust gas outlet of the vertical furnace is connected with the inlet of the fan, and the outlet of the fan is connected with the inlet of the tube chain conveyor; the iron ore metering tank, the bentonite metering tank, and the magnesia powder metering tank are all connected to the input end of the controller, and the output end of the controller is connected to the first control valve, the second control valve, the third control valve, and the fourth control valve respectively.

[0006] Furthermore, a pair of crushing rollers that rotate downward relative to each other are provided in the feed port of the double-screw feeder, and either end of the crushing rollers is transmission-connected to the rotating shaft of the double-screw feeder; a plurality of stirring teeth are transversely fixed on the spiral blades of the double-screw feeder.

[0007] Furthermore, a plurality of intermediate discs are provided on the conveying chain of the tube chain conveyor, and the discs of the tube chain conveyor are spaced apart from the intermediate discs; the center of the intermediate disc is fixed to the conveying chain, and a plurality of mounting grooves are provided in the circumferential direction of the intermediate disc, and a rolling roller is provided for rotation in the mounting groove, and the axis of the rolling roller is arranged perpendicularly to the conveying chain, and the rolling roller is in rolling contact with the inner wall of the conveying tube.

[0008] Furthermore, a second material level sensor is provided on the mixer, an output end of the second material level sensor is connected to an input end of the controller, and an output end of the controller is connected to the first control valve.

[0009] Furthermore, a humidity sensor is provided on the discharge port of the double-screw feeder, and the humidity sensor is connected to the input end of the controller.

[0010] Furthermore, a first material level sensor is installed on the recovery tank, and the first material level sensor is connected to the input end of the controller.

[0011] The second object of the present invention is implemented by the following technical solution: a control method for an iron ore pelletizing system, which includes the following control process:

[0012] S1: according to the ratio of iron ore powder, bentonite and magnesia powder, the weighing weights of the iron ore measuring tank, bentonite measuring tank and magnesia powder measuring tank are set respectively; the first control valve is opened, and the materials in the iron ore storage tank, bentonite storage tank and magnesia powder storage tank are respectively sent into the corresponding iron ore measuring tank, bentonite measuring tank and magnesia powder measuring tank through the dosing pipe, and when the corresponding weighing weight is reached, the corresponding first control valve is closed;

[0013] S2: Open the fourth control valve, discharge all the materials in the iron ore metering tank, bentonite metering tank and magnesia powder metering tank into the mixer and then close the fourth control valve;

[0014] S3: Then, the second control valve is opened by 70%, so that the material in the mixer is fed into the double screw feeder through the feeding pipe, and then mixed again by the double screw feeder and fed into the disc pelletizing machine to spray water to form green pellets;

[0015] S4: The material discharged from the disc pelletizing machine is screened by the green ball screening machine. The qualified pellets with a diameter of 5-18mm are sent to the vertical furnace by the conveyor, and the unqualified materials are sent to the recovery tank for storage via the pipe chain conveyor. In addition, the exhaust gas discharged from the vertical furnace is introduced into the pipe chain conveyor by the fan to dry the material in it;

[0016] S5: Open the third control valve, and the material collected in the recovery tank is sent to the double screw feeder of S4 through the recovery pipe;

[0017] The above S2-S5 are continuous production processes.

[0018] Furthermore, the specific control process of S5 is as follows:

[0019] S5-1: The material level in the recovery tank is detected by the first material level sensor. When the material level in the recovery tank exceeds the maximum material level set by the first material level sensor, the opening of the third control valve is increased by 10% every 20 seconds, and the opening of the second control valve is reduced by 10% every 20 seconds from the current opening, until the opening of the third control valve reaches 30% and the opening of the second control valve reaches 40%, and then the adjustment stops;

[0020] S5-2: When the material level in the recovery tank reaches the lowest level set by the first material level sensor, the third control valve is reduced by 10% every 10 seconds until it is closed, and the second control valve is increased by 10% every 10 seconds until it reaches 70%;

[0021] Furthermore, it also includes the following control process:

[0022] The controller can set the upper limit HS0 of the material humidity at the discharge port of the twin-screw feeder, and the real-time material humidity HS1 at the discharge port of the twin-screw feeder can be detected by the humidity sensor. When HS1-HS0>1%, the third control valve is reduced by 10% every 10 seconds, and the second control valve is increased by 10% every 10 seconds until the opening of the second control valve reaches 60%, the opening of the third control valve reaches 10%, or the system stops when HS1-HS0=0.

[0023] Furthermore, a first material level and a second material level are sequentially arranged in the mixer from low to high, and the material level in the mixer can be detected by a second material level sensor;

[0024] When the second material level sensor detects that the material level in the mixer reaches the second material level, the first control valve is opened and the process of S1 is repeated;

[0025] When the second material level sensor detects that the material level in the mixer reaches the first material level, the fourth control valve is opened and the process of S2 is repeated.

[0026] The advantages of the present invention include the addition of iron ore metering tanks, bentonite metering tanks, and magnesia powder metering tanks. Iron ore powder, bentonite, and magnesia powder are metered and proportioned in the corresponding metering tanks before being delivered to the mixer. This improves proportioning accuracy compared to direct metering via a star-shaped discharge valve. Unqualified raw material screened by the raw ball screening machine is transported to a recovery tank via a pipe chain conveyor. During this process, exhaust gas from the vertical furnace is fed into the conveying pipe of the pipe chain conveyor via a fan. This high-temperature exhaust gas can be used to dry the raw material within the recovery tank, reducing humidity and thereby improving uniformity in subsequent mixing with other materials. Furthermore, high-temperature dust in the exhaust gas can be directly mixed with the raw material, recycling the dust while further improving drying efficiency and enabling thermal energy recovery, thereby achieving energy conservation. Furthermore, the raw material recovered by the present invention and the material discharged from the mixer are both proportioned according to process requirements. The two are then mixed via a double-screw feeder, further ensuring the uniformity of the quality of the iron ore pellets, helping to improve the stability of the subsequent smelting process, reduce energy consumption, and conserve energy. The broken balls in the raw material are first rolled by the rolling rollers on the middle disc and dried with hot air, then crushed by the crushing rollers, and finally stirred and mixed with the materials sent from the mixer through the double-screw feeder, which can ensure the uniformity of the materials entering the disc pelletizing machine, further improve the uniformity and qualified rate of the size of the obtained raw pellets, and reduce the load and energy consumption of the disc pelletizing machine and the raw ball screening machine. In short, the present invention reduces the humidity of the recycled raw material by drying and crushing it multiple times, and then mixing it with the material with a good ratio, while improving the uniformity of the humidity and the consistency of the ratio after the two materials are mixed, thereby improving the qualified rate of the iron ore pellets, as well as the uniformity of size and quality, and helping to improve the uniformity of the mixing of iron ore pellets with other raw materials and the smelting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the system of the present invention.

[0028] Figure 2 Schematic diagram of the local structure of the tube chain conveyor.

[0029] Figure 3 Schematic diagram of the structure of the middle disk.

[0030] Figure 4 It is a structural diagram of a double screw feeder.

[0031] Iron ore storage tank 1, bentonite storage tank 2, mixer 3, double screw feeder 4, crushing roller 401, stirring rod 402, spiral blade 403, rotating shaft 404, disc pelletizer 5, raw ball screening machine 6, vertical furnace 7, pipe chain conveyor 8, conveying pipe 801, intermediate disc 803, disc 804, conveying chain 805, mounting groove 806, rolling roller 807, jacket 808, fan 9, batching pipe 10, iron ore metering tank 11, bentonite metering tank 12, first control valve 13, feeding pipe 14, fourth control valve 15, feeding pipe 16, second control valve 17, recovery tank 18, cyclone dust collector 19, recovery pipe 20, third control valve 21, controller 22, second material level sensor 23, humidity sensor 24, first material level sensor 25, magnesia powder storage tank 26, magnesia powder metering tank 27, conveyor 28. DETAILED DESCRIPTION

[0032] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate and simplify the description of the present invention and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0033] like Figures 1 to 4As shown, an iron ore pelletizing system includes an iron ore storage tank 1, a bentonite storage tank 2, a magnesia powder storage tank 26, a mixer 3, a double screw feeder 4, a disc pelletizing machine 5, a green ball screening machine 6, a vertical furnace 7, a pipe chain conveyor 8 and a fan 9. The outlets of the iron ore storage tank 1, the bentonite storage tank 2 and the magnesia powder storage tank 26 are connected to the inlets of the iron ore metering tank 11, the bentonite metering tank 12 and the magnesia powder metering tank 27 through a dosing pipe 10, respectively. A first control valve 13 is installed on the dosing pipe 10. The outlet of the metering tank 27 is connected to the feed port of the mixer 3 through a feeding pipe 14, and a fourth control valve 15 is installed on the feeding pipe 14; the outlet of the mixer 3 is connected to the inlet of the double-screw feeder 4 through a feeding pipe 16, and a second control valve 17 is installed on the feeding pipe 16; a pair of crushing rollers 401 that are arranged to rotate downward relative to each other are arranged in the feed port of the double-screw feeder 4, and either end of the crushing rollers 401 is transmission-connected to the rotating shaft 404 of the double-screw feeder 4; a number of stirring rods 402 are horizontally fixed on the spiral blades 403 of the double-screw feeder 4. In this embodiment, the rotating shaft 404 is connected to the crushing roller 401 through a chain, thereby driving the crushing roller 401 to rotate. When the crushing roller 401 rotates downward relatively, on the one hand, the material sent from the recovery tank 18 can be squeezed and crushed, and on the other hand, the material sent from the recovery tank 18 and the mixer 3 can be preliminarily mixed; then, they are transported and mixed together to the discharge port through the spiral blade 403, and the stirring rod 402 can further enhance the mixing effect of the material and improve the uniformity of the material discharged by the double-screw feeder 4.

[0034] The outlet of the double-screw feeder 4 is connected to the inlet of the disc pelletizing machine 5, and the outlet of the disc pelletizing machine 5 is connected to the inlet of the raw ball screening machine 6. The qualified material outlet of the raw ball screening machine 6 is located above the feeding end of the conveyor 28, and the discharge port of the conveyor 28 is located above the inlet of the distributor of the vertical furnace 7; the unqualified material outlet of the raw ball screening machine 6 is connected to the inlet of the tube chain conveyor 8, and the outlet of the tube chain conveyor 8 is connected to the inlet of the recovery tank 18, and the exhaust port of the recovery tank 18 is connected to the inlet of the cyclone dust collector 19, and the ash discharge port of the cyclone dust collector 19 is connected to the inlet of the mixer 3; the discharge port of the recovery tank 18 is connected to the inlet of the cyclone dust collector 19 through the recovery pipe 20 is connected to the inlet of the double-screw feeder 4, and a third control valve 21 is installed on the recovery pipe 20; the exhaust gas outlet of the vertical furnace 7 is connected to the inlet of the fan 9, and the outlet of the fan 9 is connected to the inlet of the tube chain conveyor 8; the fan 9 can send the exhaust gas discharged from the vertical furnace 7 into the tube chain conveyor 8. On the one hand, the heat of the exhaust gas can be used to dry the unqualified raw material in the tube chain conveyor 8, thereby reducing the humidity of the material that finally reaches the recovery tank 18. On the other hand, the high-temperature dust in the exhaust gas is collected in the tube chain conveyor 8, realizing the recycling of the material while allowing the high-temperature dust particles to be mixed with the biological material, which helps to enhance the drying effect. Several intermediate discs 803 are installed on the conveyor chain 805 of the tube chain conveyor 8. The discs 804 of the tube chain conveyor 8 are spaced apart from the intermediate discs 803. The center of the intermediate discs 803 is fixed to the conveyor chain 805. Several mounting slots 806 are provided in the circumferential direction of the intermediate discs 803. Rolling rollers 807 are rotatably installed in the mounting slots 806. The axes of the rolling rollers 807 are arranged perpendicular to the conveyor chain 805, and the rolling rollers 807 are in rolling contact with the inner wall of the conveyor tube 801 of the tube chain conveyor 8. During operation of the tube chain conveyor 8, the intermediate discs 803 can be driven to move along with the conveyor chain 805. The movement of the intermediate discs 803 can drive the rolling rollers 807 to roll along the inner wall of the conveyor tube 801, thereby crushing the pellets. This increases the contact area between the hot air and the recovered raw material, thereby enhancing the drying effect, further reducing the moisture content of the recovered raw material, and helping to improve the uniformity of the pellets subsequently produced. The roller 807 can have a toothed cross-section or, as shown in this embodiment, a prismatic cross-section. A jacket 808 is provided on the exterior of the conveying pipe 801. The outlet of the cyclone dust collector 19 is connected to the inlet of the jacket 808. Exhaust gas from the cyclone dust collector 19 enters the jacket 808, heating and insulating the conveying pipe 801 and enhancing the drying effect. Exhaust gas from the jacket 808 is then sent to the exhaust gas treatment system of the vertical furnace 7 for treatment.

[0035] A humidity sensor 24 is provided on the discharge port of the double-screw feeder 4, a second material level sensor 23 is provided on the mixer 3, and a first material level sensor 25 is installed on the recovery tank 18. The iron ore metering tank 11, the bentonite metering tank 12, the magnesia powder metering tank 27, the second material level sensor 23, the humidity sensor 24, and the first material level sensor 25 are all connected to the input end of the controller 22, and the output end of the controller 22 is respectively connected to the first control valve 13, the second control valve 17, the third control valve 21, and the fourth control valve 15.

[0036] The control process is as follows:

[0037] S1: According to the ratio of iron ore powder, bentonite and magnesia powder (in this embodiment, the iron ore powder has a 200 mesh sieve with a screening rate of ≥80% and a batching ratio of 95%, the bentonite has a 200 mesh sieve with a screening rate of ≥95% and a batching ratio of 2%, and the magnesia powder has a 200 mesh sieve with a screening rate of ≥85% and a batching ratio of 3%), the weighing weights of the iron ore metering tank 11, the bentonite metering tank 12 and the magnesia powder metering tank 27 are set respectively; the first control valve 13 is opened, and the iron ore storage tank 1, the bentonite storage tank 2 and the magnesia powder storage tank 27 are respectively filled with water. The materials in the stone powder storage tank 26 are respectively fed into the corresponding iron ore metering tank 11, bentonite metering tank 12 and magnesia powder metering tank 27 through the dosing pipe 10. When the corresponding weighing weight is reached, the corresponding first control valve 13 is closed; the iron ore powder stored in the iron ore metering tank 11, the bentonite stored in the bentonite metering tank 12 and the magnesia powder stored in the magnesia powder metering tank 27 are first metered and proportioned by the corresponding metering tanks, which is more accurate than the metering of the star-shaped discharge valve.

[0038] S2: Open the fourth control valve 15, discharge all the materials in the iron ore metering tank 11, the bentonite metering tank 12 and the magnesia powder metering tank 27 into the mixer 3, and then close the fourth control valve 15; the materials accurately measured by the iron ore metering tank 11, the bentonite metering tank 12 and the magnesia powder metering tank 27 are discharged into the mixer 3 together for mixing, which can ensure the accuracy of the material ratio discharged from the mixer 3.

[0039] S3: Then, the second control valve 17 is opened by 70%, so that the material in the mixer 3 is fed into the double screw feeder 4 through the feeding pipe 16, and then mixed again by the double screw feeder 4 and fed into the disc pelletizing machine 5 to spray water to form green pellets;

[0040] S4: The material discharged from the disc pelletizing machine 5 is screened by the raw ball screening machine 6, and the qualified pellets with a diameter of 5-18 mm are sent to the vertical furnace 7 by the conveyor 28, and the unqualified materials are sent to the recovery tank 18 for storage via the pipe chain conveyor 8, and the exhaust gas discharged from the vertical furnace 7 is introduced into the pipe chain conveyor 8 by the fan 9 to dry the material therein; the exhaust gas from the vertical furnace 7 enters the pipe chain conveyor 8 through the fan 9, which can dry the raw material inside it, and the high-temperature dust in the exhaust gas can be directly mixed with the raw material, further enhancing the drying effect; and during the operation of the pipe chain conveyor 8, the conveying chain 805 can drive the middle disc 803 to move together, and then drive the rolling roller 807 to rotate to crush the broken balls, increase the contact area between the hot air and the material, and help enhance the drying effect.

[0041] S5: Open the third control valve 21, and the material collected in the recovery tank 18 is sent to the double screw feeder 4 in S4 through the recovery pipe 20;

[0042] The specific control process of S5 is as follows:

[0043] S5-1: The material level in the recovery tank 18 is detected by the first material level sensor 25. When it is detected that the material level in the recovery tank 18 exceeds the maximum material level set by the first material level sensor 25, the opening of the third control valve 21 is increased by 10% every 20 seconds, and the opening of the second control valve 17 is reduced by 10% every 20 seconds from the current opening, until the opening of the third control valve 21 reaches 30% and the opening of the second control valve 17 reaches 40%, and the adjustment is stopped; the unqualified raw material collected in the recovery tank 18 can be sent to the double screw feeder 4 through the recovery pipe 20, and mixed with the well-proportioned material sent from the mixer 3 through the double screw feeder 4 to realize the recovery of unqualified raw material, and the well-proportioned material is mixed with the recycled material, which can further improve the material ratio accuracy.

[0044] S5-2: When the material level in the recovery tank 18 reaches the lowest material level set by the first material level sensor 25, the third control valve 21 is reduced by 10% every 10 seconds until it is closed, and the second control valve 17 is increased by 10% every 10 seconds until it is adjusted to 70%; the detection of the first material level sensor 25 can timely detect the lack of material in the recovery tank 18. At this time, the third control valve 21 is gradually closed, and the opening of the second control valve 17 is increased, and finally the mixer 3 is switched to feed the double screw feeder 4 entirely.

[0045] It also includes the following control process: the controller 22 can set the upper limit HS0 of the material humidity at the discharge port of the double screw feeder 4, and the humidity sensor 24 can detect the real-time material humidity HS1 at the discharge port of the double screw feeder 4. When HS1-HS0>1%, it indicates that the humidity of the material sent from the recovery tank 18 is too high. At this time, the third control valve 21 is reduced by 10% every 10 seconds, and the second control valve 17 is increased by 10% every 10 seconds until the opening of the second regulating valve reaches 60%, the opening of the third control valve 21 reaches 10%, or HS1-HS0=0 is stopped; in this way, the humidity of the material entering the disc pelletizing machine 5 can be controlled to avoid the humidity of the entering material being too high, thereby ensuring the uniformity of the iron ore pellets discharged from the disc pelletizing machine 5.

[0046] The above S2-S5 are continuous production processes; a first material level and a second material level are sequentially set in the mixer 3 from low to high, and the material level in the mixer 3 can be detected by the second material level sensor 23. When the second material level sensor 23 detects that the material level in the mixer 3 has reached the second material level, it indicates that the material in the mixer 3 is about to be insufficient, and the process of S1 is repeated. The materials in the iron ore storage tank 1, the bentonite storage tank 2, and the magnesia powder storage tank 26 are added to the corresponding iron ore metering tank 11, the bentonite metering tank 12, and the magnesia powder metering tank 27 according to the set ratio for standby use; when the second material level sensor 23 detects that the material level in the mixer 3 has reached the first material level, it indicates that the material in the mixer 3 is insufficient, and the process of S2 is repeated. The materials in the iron ore metering tank 11, the bentonite metering tank 12, and the magnesia powder metering tank 27 that have been measured in advance are added to the mixer 3 to achieve accurate proportioning, which helps to improve the accuracy of the ingredients.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An iron ore pelletizing system, characterized in that: It includes an iron ore storage tank, a bentonite storage tank, a magnesia powder storage tank, a mixer, a double screw feeder, a disc pelletizing machine, a green ball screening machine, a vertical furnace, a pipe chain conveyor and a fan. The outlets of the iron ore storage tank, the bentonite storage tank and the magnesia powder storage tank are connected to the inlets of the iron ore metering tank, the bentonite metering tank and the magnesia powder metering tank through a feed pipe, respectively. A first control valve is installed on the feed pipe. The outlets of the iron ore metering tank, the bentonite metering tank and the magnesia powder metering tank are connected to the feed port of the mixer through a feed pipe, respectively. A fourth control valve is installed; the outlet of the mixer is connected to the inlet of the double-screw feeder through a feeding pipe, and a second control valve is installed on the feeding pipe; the outlet of the double-screw feeder is connected to the inlet of the disc pelletizing machine, and the outlet of the disc pelletizing machine is connected to the inlet of the green ball screening machine. The qualified material outlet of the green ball screening machine is located above the feeding end of the conveyor, and the discharge port of the conveyor is located above the inlet of the distributor of the vertical furnace; the unqualified material outlet of the green ball screening machine is connected to the inlet of the pipe chain conveyor, and the pipe chain conveyor The outlet of the conveyor is connected to the inlet of the recovery tank, the exhaust port of the recovery tank is connected to the inlet of the cyclone dust collector, and the ash discharge port of the cyclone dust collector is connected to the inlet of the mixer; the discharge port of the recovery tank is connected to the inlet of the double-screw feeder through a recovery pipe, and a third control valve is installed on the recovery pipe; the tail gas outlet of the vertical furnace is connected to the inlet of the fan, and the outlet of the fan is connected to the inlet of the pipe chain conveyor; the iron ore metering tank, the bentonite metering tank, and the magnesia powder metering tank are all connected to the input end of the controller, and the controller The output ends are respectively connected to the first control valve, the second control valve, the third control valve, and the fourth control valve; a plurality of intermediate discs are arranged on the conveying chain of the pipe chain conveyor, and the discs of the pipe chain conveyor are spaced apart from the intermediate discs; the center of the intermediate disc is fixed to the conveying chain, and a plurality of mounting grooves are provided in the circumferential direction of the intermediate disc, and a rolling roller is rotatably provided in the mounting groove, and the axis of the rolling roller is arranged perpendicularly to the conveying chain, and the rolling roller is in rolling contact with the inner wall of the conveying pipe of the pipe chain conveyor.

2. The iron ore pelletizing system according to claim 1, characterized in that: A pair of crushing rollers that rotate downward relative to each other are arranged in the feed port of the double-screw feeder, and either end of the crushing rollers is transmission-connected to the rotating shaft of the double-screw feeder; a plurality of stirring rods are transversely fixed on the spiral blades of the double-screw feeder.

3. The iron ore pelletizing system according to claim 1, characterized in that: A second material level sensor is provided on the mixer, an output end of the second material level sensor is connected to an input end of the controller, and an output end of the controller is connected to the first control valve.

4. The iron ore pelletizing system according to claim 1, characterized in that: A humidity sensor is provided on the discharge port of the double-screw feeder, and the humidity sensor is connected to the input end of the controller.

5. The iron ore pelletizing system according to claim 1, characterized in that: A first material level sensor is installed on the recovery tank, and the first material level sensor is connected to the input end of the controller.

6. The control method of an iron ore pelletizing system according to any one of claims 1 to 5, characterized in that: It includes the following control processes: S1: according to the ratio of iron ore powder, bentonite and magnesia powder, the weighing weights of the iron ore measuring tank, bentonite measuring tank and magnesia powder measuring tank are set respectively; the first control valve is opened, and the materials in the iron ore storage tank, bentonite storage tank and magnesia powder storage tank are respectively sent into the corresponding iron ore measuring tank, bentonite measuring tank and magnesia powder measuring tank through the dosing pipe, and when the corresponding weighing weight is reached, the corresponding first control valve is closed; S2: Open the fourth control valve, discharge all the materials in the iron ore metering tank, bentonite metering tank and magnesia powder metering tank into the mixer and then close the fourth control valve; S3: Then, the second control valve is opened by 70%, so that the material in the mixer is fed into the double screw feeder through the feeding pipe, and then mixed again by the double screw feeder and fed into the disc pelletizing machine to spray water to form green pellets; S4: The material discharged from the disc pelletizing machine is screened by the green ball screening machine. The qualified pellets with a diameter of 5-18mm are sent to the vertical furnace by the conveyor, and the unqualified materials are sent to the recovery tank for storage via the pipe chain conveyor. In addition, the exhaust gas discharged from the vertical furnace is introduced into the pipe chain conveyor by the fan to dry the material in it; S5: Open the third control valve, and the material collected in the recovery tank is sent to the double screw feeder of S4 through the recovery pipe; The above S2-S5 are continuous production processes.

7. The control method of the iron ore pelletizing system according to claim 6, characterized in that: The specific control process of S5 is as follows: S5-1: The material level in the recovery tank is detected by the first material level sensor. When the material level in the recovery tank exceeds the maximum material level set by the first material level sensor, the opening of the third control valve is increased by 10% every 20 seconds, and the opening of the second control valve is reduced by 10% every 20 seconds from the current opening, until the opening of the third control valve reaches 30% and the opening of the second control valve reaches 40%, and then the adjustment stops; S5-2: When the material level in the recovery tank reaches the lowest level set by the first material level sensor, the third control valve is reduced by 10% every 10 seconds until it is closed, and the second control valve is increased by 10% every 10 seconds until it is adjusted to 70%.

8. The control method of the iron ore pelletizing system according to claim 7, characterized in that: It also includes the following control processes: The controller sets the upper limit HS0 of the material humidity at the discharge port of the twin-screw feeder, and the humidity sensor detects the real-time material humidity HS1 at the discharge port of the twin-screw feeder. When HS1-HS0>1%, the third control valve is reduced by 10% every 10 seconds, and the second control valve is increased by 10% every 10 seconds until the opening of the second regulating valve reaches 60%, the opening of the third control valve reaches 10%, or the control stops when HS1-HS0=0.

9. The control method of an iron ore pelletizing system according to claim 6, characterized in that: A first material level and a second material level are sequentially set in the mixer from low to high, and the material level in the mixer is detected by a second material level sensor; when the second material level sensor detects that the material level in the mixer reaches the second material level, the process of S1 is repeated; when the second material level sensor detects that the material level in the mixer reaches the first material level, the process of S2 is repeated.

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