Rotary hearth furnace undersize powder ball pressing method and ball pressing system

Abstract

The rotary hearth furnace undersize powder ball pressing method comprises the following steps that S1, a discharging opening of an undersize powder bin communicates with a feeding opening of a three-way distributor, on the basis that the output amount of undersize powder and the ball pressing requirement are determined, the material distributing mode of the three-way distributor is dynamically switched according to the production mode, and the output amount of the undersize powder is adjusted; a proper amount of undersize powder is fed into a raw material scraper conveyor to be mixed with the fly ash and a binding agent, and a mixed material is obtained; s2, conveying the mixed material and a proper amount of water into a mixer to form a formed material with standard water content; and S3, the formed materials are fed into a ball pressing machine to be machined into formed pellets, then the formed pellets are dried, after the obtained dried pellets are screened through a screening machine, oversize powder is stored in a cold pressing ball bin, and undersize powder is returned into the material mixing machine to be subjected to secondary pressing, so that a material closed-loop cycle is formed. The cold-pressed pellets prepared through the method can be conveyed to a converter and an electric furnace for steelmaking, and comprehensive utilization of resources is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical solid waste treatment, and in particular to a method and system for briquetting powder under a rotary hearth furnace screen. Background Art

[0002] Rotary hearth furnaces are commonly used for comprehensive solid waste recycling within steel companies. They reduce iron oxide in various iron- and zinc-containing dust sludges to metallic iron, and zinc oxide to zinc. Ultimately, they produce three products: zinc powder, metallized pellets, and pellet undersize. Zinc powder can be packaged and exported directly, while metallized pellets can be used as a steelmaking coolant. The pellet undersize is typically humidified and transported to sintering facilities for reuse.

[0003] Since pellet undersize often does not react fully, resulting in a high zinc content (between 1.5% and 2.5%), it will indirectly increase the zinc load of the blast furnace after being sent to sintering (the zinc content per ton of molten iron is required to be below 0.4kg). Zinc is continuously enriched and precipitated in the blast furnace, making the blast furnace more prone to nodules. Therefore, sintering has basically stopped accepting pellet undersize, and it is difficult for the converter to directly accept powder materials, making the treatment of pellet undersize a problem. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method and system for briquetting powder under the screen of a rotary hearth furnace.

[0005] The present invention solves the technical problem by adopting the following technical solutions.

[0006] The present invention provides a method for pelletizing powder under a rotary hearth furnace sieve, comprising the following steps:

[0007] S1. Connect the discharge port of the undersize powder bin to the feed port of the three-way distributor. Based on the output of the undersize powder and the demand for pelletizing, dynamically switch the distribution mode of the three-way distributor according to the production mode, and feed an appropriate amount of undersize powder into the raw material scraper conveyor to mix with the dust removal ash and binder to obtain a mixed material;

[0008] S2, transporting the mixed material and an appropriate amount of water into a mixer to form a molding material with a standard moisture content;

[0009] S3. The molding material is sent to the pelletizing machine to be processed into molding pellets, and then the molding pellets are dried. The obtained dried pellets are screened by the screening machine, and the screened powder is stored in the cold pressing ball bin, and the screened powder is returned to the mixer for secondary pressing to form a closed material circulation.

[0010] The present invention also provides a rotary hearth furnace under-screen powder briquetting system for implementing the above method, comprising: a rotary hearth furnace, a cylindrical cooler, a chain bucket conveyor, a first screening machine, an under-screen powder bin, a three-way distributor, a raw material scraper, a mixer, a briquetting machine, a second screening machine, a binder bin, a humidifier, a dust removal ash bin, a finished product bin, and a cold-pressed bin, wherein:

[0011] The rotary hearth furnace is connected to the feed port of the first screening machine through the cylindrical cooler and the chain bucket conveyor in sequence. The discharge port of the first screening machine includes discharge port I and discharge port II; discharge port I is connected to the feed port of the finished ball bin, discharge port II is connected to the feed port of the under-screen powder bin, the discharge port of the under-screen powder bin is connected to the feed port of the three-way distributor, the discharge port of the three-way distributor includes discharge port III and discharge port IV, discharge port III is connected to the feed port of the humidifier, and discharge port IV is connected to the feed port of the raw material scraper. The feed port of the raw material scraper is also connected to the binder bin and the dust removal ash bin, the discharge port of the raw material scraper is connected to the feed port of the mixer, the discharge port of the mixer is connected to the feed port of the ball press, the discharge port of the ball press is connected to the feed port of the dryer, the discharge port of the dryer is connected to the feed port of the second screening machine, the discharge port of the second screening machine includes discharge port V and discharge port VI, discharge port V is connected to the feed port of the cold pressing ball bin, and discharge port VI is connected to the feed port of the mixer.

[0012] The present invention has the following beneficial effects:

[0013] The present invention provides a method and system for briquetting rotary hearth furnace undersize powder. This method mixes the rotary hearth furnace undersize powder with a binder and dust removal ash, humidifies it, and directly processes it into cold-pressed pellets. These pellets can then be directly sent to steelmaking for use as a coolant or raw material. This effectively solves the problem of undersize powder having nowhere to go due to excessive zinc content in traditional processes, achieving full, high-value-added utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 Schematic diagram of the powder pelletizing system under the rotary hearth furnace screen. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0017] The following is a detailed description of a method and system for briquetting powder under a rotary hearth furnace provided by an embodiment of the present invention.

[0018] In a first aspect, an embodiment of the present invention provides a method for pelletizing powder under a rotary hearth furnace, comprising the following steps:

[0019] S1. Connect the discharge port of the undersize powder bin to the feed port of the three-way distributor. Based on the output of the undersize powder and the demand for pelletizing, dynamically switch the distribution mode of the three-way distributor according to the production mode, and feed an appropriate amount of undersize powder into the raw material scraper conveyor to mix with the dust removal ash and binder to obtain a mixed material;

[0020] S2, transporting the mixed material and an appropriate amount of water into a mixer to form a molding material with a standard moisture content;

[0021] S3. The molding material is sent to the pelletizing machine to be processed into molding pellets, and then the molding pellets are dried. The obtained dried pellets are screened by the screening machine, and the screened powder is stored in the cold pressing ball bin, and the screened powder is returned to the mixer for secondary pressing to form a closed material circulation.

[0022] The present invention provides a method for pelletizing undersize powder from a rotary hearth furnace. The undersize powder from a rotary hearth furnace is mixed with a binder and dust removal ash, and is directly processed into cold-pressed pellets after humidification. At the beginning of use, the undersize powder is dynamically switched according to the production mode based on the output of the undersize powder, the need for pelletizing, etc., and the distribution mode of the three-way distributor is dynamically switched. After an appropriate amount of undersize powder is mixed with a binder and dust removal ash, the mixed material is humidified to prepare a molding material, and the molding material is then used to prepare cold-pressed pellets. In addition, during the preparation of the cold-pressed pellets, the substandard undersize powder that is screened out is returned for reuse. The obtained cold-pressed pellets are all qualified cold-pressed pellets that meet the preset specifications, and no wastewater or waste is produced. The prepared cold-pressed pellets can be directly sent to steelmaking for use as a coolant or raw material, which completely solves the problem of "nowhere to go" caused by excessive zinc content in the traditional process, and realizes the full high-value-added utilization of resources.

[0023] In some optional embodiments, the distribution mode of the three-way distributor is dynamically switched according to the production mode, including: when ball pressing is required, most of the undersize powder is sent to the raw material scraper conveyor through the three-way distributor; when ball pressing is not required, the output of the undersize powder exceeds the ball pressing processing capacity or the ball pressing system fails, most of the undersize powder is stored in the undersize powder bin and / or sent to the humidifier through the three-way distributor for humidification, and then loaded onto a truck for transfer.

[0024] The rotary hearth furnace undersize powder briquetting method provided by the present invention can flexibly adjust the path of the undersize powder according to the undersize powder output and the briquetting demand by arranging a three-way distributor below the undersize powder bin of the pelletizer. For example, when there is no need to perform briquetting, when the briquetting process fails, or when the undersize powder output exceeds the amount required for briquetting, most of the undersize powder is stored in the undersize powder bin and / or sent to a humidifier through a three-way distributor for humidification before being loaded and transferred; when briquetting is required, the undersize powder is measured by a rotor scale and then enters a raw material scraper conveyor. During the entire process, not only can the amount of undersize powder used be accurately controlled, but the path of the undersize powder can also be flexibly adjusted.

[0025] In some optional embodiments, the mass proportion of the binder in the mixed material is 3% to 8%, the mass proportion of the dust ash is 5% to 15%, and the mass proportion of the undersize powder is 77% to 92%;

[0026] Preferably, the binder includes at least one of bentonite, cement, and composite adhesives, and the dust ash includes at least one of blast furnace dust ash and converter dust ash.

[0027] Preferably, the mixed material is mixed with measured water to form a molding material with a standard moisture content. After the molding material is pressed into balls, dried and sieved, a sieve powder with a particle size of more than 5 mm is obtained.

[0028] In a second aspect, an embodiment of the present invention provides a rotary hearth furnace under-screen powder briquetting system for implementing the above method, comprising: a rotary hearth furnace, a cylindrical cooler, a chain bucket conveyor, a first screening machine, an under-screen powder bin, a three-way distributor, a raw material scraper, a mixer, a briquetting machine, a second screening machine, a binder bin, a humidifier, a dust removal ash bin, a finished product bin, and a cold-pressed bin, wherein:

[0029] The rotary hearth furnace is connected to the feed port of the first screening machine through the cylindrical cooler and the chain bucket conveyor in sequence. The discharge port of the first screening machine includes discharge port I and discharge port II; discharge port I is connected to the feed port of the finished ball bin, discharge port II is connected to the feed port of the under-screen powder bin, the discharge port of the under-screen powder bin is connected to the feed port of the three-way distributor, the discharge port of the three-way distributor includes discharge port III and discharge port IV, discharge port III is connected to the feed port of the humidifier, and discharge port IV is connected to the feed port of the raw material scraper. The feed port of the raw material scraper is also connected to the binder bin and the dust removal ash bin, the discharge port of the raw material scraper is connected to the feed port of the mixer, the discharge port of the mixer is connected to the feed port of the ball press, the discharge port of the ball press is connected to the feed port of the dryer, the discharge port of the dryer is connected to the feed port of the second screening machine, the discharge port of the second screening machine includes discharge port V and discharge port VI, discharge port V is connected to the feed port of the cold pressing ball bin, and discharge port VI is connected to the feed port of the mixer.

[0030] In some optional embodiments, the undersize powder bin is connected to the three-way distributor via a rotor scale, and the binder bin and the dust removal ash bin are both connected to the raw material scraper via independent metering equipment;

[0031] Preferably, the independent metering equipment is a rotor scale + a screw feeder, and the metering accuracy error of the rotor scale is ≤0.5%.

[0032] In some optional implementations, a buffer bin is provided between the mixer and the ball press, and a variable frequency quantitative feeder is configured at the bottom of the buffer bin to achieve precise feeding control, and then the material is fed into the ball press.

[0033] The present invention provides a rotary hearth furnace undersize powder briquetting system. When using this briquetting system to produce cold-pressed balls, high-precision control of raw material usage is achieved. For example, each raw material, such as undersize powder, dust removal ash, binder, water, and molding material, is precisely measured. This not only allows accurate information on the usage of each material, but also allows for timely adjustment of the formula and ratio of various raw materials based on the properties of the raw materials to ensure product quality. The system is adaptable to different binders and dust removal ash, meeting diverse raw material processing needs.

[0034] In some optional embodiments, the mixer is connected to the buffer bin via a 1# belt conveyor, the ball press is connected to the dryer via a 2# belt conveyor, and the second screening machine and the cold-pressed ball bin are connected via a 3# belt conveyor.

[0035] In some optional embodiments, sealing covers are provided on the 1# belt conveyor, the 2# belt conveyor, the 3# belt conveyor and the quantitative feeder to suppress dust.

[0036] In some optional embodiments, belt conveyors 1#, 2#, 3#, the quantitative feeder, the first screener, and the second screener are all equipped with gas collection hoods connected to a bag dust removal system, creating a negative pressure within the system. The rotary hearth furnace under-screen powder pelletizing system provided by the present invention features a fully sealed negative pressure system throughout the entire process, employing a fully sealed design for material transfer, storage, and processing. Gas collection hoods are also installed at key locations, eliminating dust spillage and wastewater discharge, providing an efficient and clean solution for solid waste resource utilization in the steel industry.

[0037] In some optional embodiments, a control box is installed for all devices in the ball pressing system and connected to a PLC control cabinet with a communication cable to establish an automatic control system. A control box is installed for all devices in the ball pressing system, and remote interlocking is performed. All devices are controlled by PLCs, enabling remote operation and one-button start.

[0038] The present invention will be further described below with reference to the embodiments.

[0039] Example 1

[0040] A rotary hearth furnace under-screen powder briquetting system, see Figure 1 , including: rotary hearth furnace, drum cooler, chain bucket conveyor, first screening machine, under-screen powder bin, three-way distributor, raw material scraper, mixer, ball press, second screening machine, binder bin, humidifier, dust removal bin, finished product bin and cold pressed bin, including:

[0041] The rotary hearth furnace is connected to the inlet of the first screening machine through the cylindrical cooler and the chain bucket conveyor in sequence. The discharge port of the first screening machine includes discharge port I and discharge port II; discharge port I is connected to the inlet of the finished ball bin, discharge port II is connected to the inlet of the undersize powder bin, the discharge port of the undersize powder bin is connected to the inlet of the three-way distributor, the discharge port of the three-way distributor includes discharge port III and discharge port IV, discharge port III is connected to the inlet of the humidifier, discharge port IV is connected to the inlet of the raw material scraper, the inlet of the raw material scraper is also connected to the binder bin and the dust ash bin, and the undersize powder bin, binder bin and dust ash bin are all connected to the raw material scraper through a rotor scale + screw feeder;

[0042] The discharge port of the raw material scraper is connected to the feed port of the mixer, the discharge port of the mixer is connected to the feed port of the buffer bin through the 1# belt conveyor, the outlet material of the buffer bin is connected to the feed port of the ball press through the quantitative feeder, the discharge port of the ball press is connected to the feed port of the second screening machine through the 2# belt conveyor, and a blower is arranged above the 2# belt conveyor to dry the material on the screen. The discharge port of the second screening machine includes discharge port V and discharge port VI, discharge port V is connected to the feed port of the cold pressing ball bin through the 3# belt conveyor, and discharge port VI is connected to the feed port of the mixer through the return scraper.

[0043] Furthermore, sealing covers are provided on the 1# belt conveyor, the 2# belt conveyor, the 3# belt conveyor and the quantitative feeder to suppress dust.

[0044] Furthermore, 1# belt conveyor, 2# belt conveyor, 3# belt conveyor, quantitative feeder, first screening machine and second screening machine are all provided with air collecting hoods, and the air collecting hoods are connected to the bag dust removal system to form negative pressure in the system.

[0045] Furthermore, control boxes are set up for all equipment in the production line, connected to the PLC control cabinet with communication cables, and an automatic control system is established.

[0046] Example 2

[0047] A method for pelletizing powder under a rotary hearth furnace comprises the following steps:

[0048] S1. First, a three-way distributor is set below the pelletizing powder bin, which has two operating modes: when there is no need for pelletizing, the powder under the screen is directly loaded onto the truck; when pelletizing is required, the powder under the screen is measured by the rotor scale and then enters the raw material scraper conveyor.

[0049] S2. Meanwhile, the dust and binder are quantitatively distributed through independent metering systems (rotor scale + screw feeder), with the rotor scale's metering accuracy error ≤0.5%. They are then mixed with the undersize powder on a raw material scraper conveyor (the binder accounts for 3% to 8% by weight of the mixed material, the dust ash accounts for 5% to 15% by weight, and the undersize powder accounts for 77% to 92% by weight). The three raw materials are then transported via the raw material scraper conveyor to a humidifying mixer connected to a water pipe. The metered water is then evenly mixed with the raw materials to form a molding material with a standard moisture content.

[0050] S3. The mixed material is sent to the buffer bin for temporary storage via the 1# belt conveyor. A variable frequency quantitative feeder is installed at the bottom of the bin to achieve precise material discharge control. After the mixed material is sent to the pelletizing machine, it is processed into oval cold-pressed pellets of size 50mm×40mm×22mm (size can be customized) and then sent to the 2# belt conveyor. During the conveyance of the formed pellets on the 2# belt conveyor, a blower is used to preliminarily dry the surface of the pellets. The subsequent screening machine is equipped with a 5mm mesh. Qualified products (>5mm) that pass the screen are transferred to the finished product bin via the 3# belt conveyor for storage. The powder that falls below the screen (≤5mm) is returned to the 1# belt conveyor via the return scraper conveyor for secondary pressing, forming a closed material circulation.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for pelletizing powder under the sieve of a rotary hearth furnace, characterized by: The following steps are involved: S1. Connect the discharge port of the undersize powder bin to the feed port of the three-way distributor. Based on the output of the undersize powder and the demand for pelletizing, dynamically switch the distribution mode of the three-way distributor according to the production mode, and feed an appropriate amount of undersize powder into the raw material scraper conveyor to mix with the dust removal ash and binder to obtain a mixed material; S2, conveying the mixed material and an appropriate amount of water into a mixer to form a molding material with a standard moisture content; S3. The molding material is fed into a pelletizing machine to produce molding pellets, and the molding pellets are then dried. The obtained dried pellets are screened by a screening machine, and the screened powder is stored in a cold pressing ball bin, and the screened powder is returned to the mixer for secondary pressing, forming a closed material circulation.

2. The method for pelletizing powder under the rotary hearth furnace according to claim 1, characterized in that: The material distribution mode of the three-way distributor is dynamically switched according to the production mode, including: when ball pressing is required, most of the undersize powder is sent to the raw material scraper conveyor through the three-way distributor; when ball pressing is not required, the undersize powder output exceeds the ball pressing processing capacity or the ball pressing system fails, most of the undersize powder is stored in the undersize powder bin and / or sent to the humidifier through the three-way distributor for humidification before being loaded and transferred.

3. The method for pelletizing powder under the rotary hearth furnace according to claim 1, characterized in that: The mass proportion of the binder in the mixed material is 3% to 8%, the mass proportion of the dust ash is 5% to 15%, and the mass proportion of the undersize powder is 77% to 92%; Preferably, the binder includes at least one of bentonite, cement, and composite adhesive, and the dust ash includes at least one of blast furnace dust ash and converter dust ash; Preferably, the mixed material is mixed with measured water to form a molding material with a standard moisture content, and the molding material is pelletized, dried and sieved to obtain a sieve powder with a particle size of more than 5 mm.

4. A rotary hearth furnace under-sieve powder briquetting system for implementing the method according to any one of claims 1 to 3, characterized in that: include: Rotary hearth furnace, cylindrical cooler, chain bucket conveyor, first screening machine, under-screen powder bin, three-way distributor, raw material scraper, mixer, ball press, second screening machine, binder bin, humidifier, dust removal bin, finished product bin and cold-pressed bin, including: The rotary hearth furnace is connected to the feed port of the first screening machine through a cylindrical cooler and a chain bucket conveyor in sequence. The discharge port of the first screening machine includes a discharge port I and a discharge port II. The discharge port I is connected to the feed port of the finished ball bin, the discharge port II is connected to the feed port of the under-screen powder bin, the discharge port of the under-screen powder bin is connected to the feed port of the three-way distributor, the discharge port of the three-way distributor includes a discharge port III and a discharge port IV, the discharge port III is connected to the feed port of the humidifier, and the discharge port IV is connected to the feed port of the raw material scraper. The feed port of the raw material scraper is also connected to the binder bin and the dust removal ash bin, the discharge port of the raw material scraper is connected to the feed port of the mixer, the discharge port of the mixer is connected to the feed port of the ball press, the discharge port of the ball press is connected to the feed port of the dryer, the discharge port of the dryer is connected to the feed port of the second screening machine, the discharge port of the second screening machine includes discharge port V and discharge port VI, the discharge port V is connected to the feed port of the cold pressed ball bin, and the discharge port VI is connected to the feed port of the mixer.

5. The rotary hearth furnace under-sieve powder briquetting system according to claim 4, characterized in that: The under-sieve powder bin is connected to the three-way distributor via a rotor scale, and the binder bin and the dust removal ash bin are both connected to the raw material scraper via independent metering equipment; Preferably, the independent metering equipment is a rotor scale + a screw feeder, and the metering accuracy error of the rotor scale is ≤0.5%.

6. The method for pelletizing powder under the rotary hearth furnace according to claim 4, characterized in that: A buffer bin is further provided between the mixer and the ball press, and a variable frequency quantitative feeder is arranged at the bottom of the buffer bin to realize precise feeding control and then feed the materials into the ball press.

7. The rotary hearth furnace under-sieve powder briquetting system according to claim 6, characterized in that: The mixer is connected to the buffer bin via a 1# belt conveyor, the ball press is connected to the dryer via a 2# belt conveyor, and the second screening machine is connected to the cold-pressed ball bin via a 3# belt conveyor.

8. The rotary hearth furnace under-sieve powder briquetting system according to claim 7, characterized in that: Sealing covers are installed on 1# belt conveyor, 2# belt conveyor, 3# belt conveyor and quantitative feeder to suppress dust.

9. The rotary hearth furnace under-sieve powder briquetting system according to claim 7, characterized in that: 1# belt conveyor, 2# belt conveyor, 3# belt conveyor, quantitative feeder, first screening machine and second screening machine are all equipped with air collection hoods, which are connected to the bag dust removal system to form negative pressure in the system.

10. The rotary hearth furnace under-sieve powder briquetting system according to claim 4, characterized in that: Set up control boxes for all equipment in the production line, connect them to the PLC control cabinet with communication cables, and establish an automatic control system.

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