Cold-rolled acid regeneration and impurity removal sludge co-processing device and processing method thereof

Abstract

The present application relates to the technical fields of environmental protection and waste utilization, and discloses a kind of cold-rolled acid regeneration impurity-removing sludge collaborative disposal device, including calcination furnace, the upper feed inlet of calcination furnace is connected with stock bin by crusher, and the lower discharge port is connected with connecting bin, the air inlet of calcination furnace is connected with hot blast furnace, and the air outlet is connected with dust cloth bag, and the outlet of dust cloth bag is connected with acid regeneration chlorine-containing gas disposal and utilization system.The present application also discloses a kind of disposal method of cold-rolled acid regeneration impurity-removing sludge collaborative disposal device.The present application cold-rolled acid regeneration impurity-removing sludge collaborative disposal device and its disposal method do not pass through water washing, directly pass through fire roasting method, realize high proportion decomposition of chloride ion in sludge, dispose and utilize the chlorine-containing gas of decomposition, realize the reduction of sludge disposal and high-quality utilization.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and waste utilization technology, specifically to a co-processing device and method for cold-rolled acid regeneration and impurity removal sludge. Background Technology

[0002] The waste liquid generated by the cold rolling mill of steel enterprises using hydrochloric acid to pickle strip steel mainly consists of FeCl2, with a small amount of FeCl3 and trace amounts of SiO2. The waste liquid is recycled using a spray roasting process. Regeneration requires desiliconization and impurity removal of the waste liquid. When the silica content in the waste liquid is low, impurity removal is performed directly; when the silica content is high, pre-desiliconization and impurity removal are performed before final desiliconization and impurity removal. Impurity removal mainly involves adding ammonia water to the waste liquid for neutralization, followed by air oxidation to generate Fe(OH)3. Fe(OH)3 adsorbs silica and other impurities in the waste liquid. During the Fe(OH)3 generation process, a flocculant is added to increase the size and precipitate the Fe(OH)3 particles containing impurities. Solid-liquid separation is then achieved through pressure filtration. The resulting pure liquid is roasted to obtain high-purity Fe2O3, which is sold at a high price. The chlorine-containing gas generated during roasting is treated by a pre-concentration tower, absorption tower, and washing tower to obtain concentrated HCl, which is then returned to the strip steel pickling process for reuse. The exhaust gas meets emission standards. Furthermore, the sludge produced during separation has high water and chlorine content and is highly corrosive, requiring special treatment. The primary disposal method is landfill. The main components of the sludge are Fe(OH)3, FeO(OH), and small amounts of FeCl2, FeCl3, and trace amounts of SiO2. Landfill disposal not only wastes iron resources, the main component of the sludge, but also occupies limited land resources. my country is promoting the construction of "zero-waste cities," and the "decrease in the amount of industrial hazardous waste disposed of by landfill" is an important indicator. The government is restricting the proportion of landfill disposal; therefore, it is necessary to explore ways to utilize the acid-regenerated sludge for resource recovery.

[0003] Chinese Patent (Publication Date: February 18, 2009, Publication No.: CN101367085A) discloses an apparatus and method for feeding filter cake into a burner on a roasting tower via a feeder, heating and drying the filter cake as it falls from the top of the tower to decompose it into iron oxide powder, and then absorbing the gas through pure water spraying and returning it for pickling. However, in this patent, because the pickled iron oxide red desilication filter cake has undergone flocculation and plate and frame filtration, the material is tightly connected, and the time it takes to fall from the top of the tower is extremely short. Heating and drying only occurs during this short process, so the decomposition effect of chloride in the filter cake is limited, affecting the harmless treatment effect. Secondly, the gas cannot directly form industrial hydrochloric acid by simply spraying it with pure water; heating and concentration are generally required. Thirdly, this method only considers the utilization of chlorine-containing gas in the mixed gas, and does not consider the treatment of other gases after the combustion of fuel gas and air, which will cause secondary pollution.

[0004] Chinese patent (publication date: June 19, 2020, publication number: CN113816571A) discloses a method for washing desilication sludge with water at a water-to-solid ratio of 5-12:1 for 30-60 minutes, followed by high-pressure dehydration, calcination at 300-450℃ for 30-60 minutes, and dechlorination. The residue after calcination is used in metallurgical processes, and the flue gas is cooled, deacidified, and purified before being discharged. The resulting dilute acid solution is then reused. However, in this patent, the filtrate increases by approximately 5-12 times after washing. The filtrate is acidic and classified as hazardous waste, significantly increasing the amount of hazardous waste generated. When the filtrate is used in the low-temperature calcination flue gas cooling process of the filter cake, the temperature needs to be cooled from 300-450℃ to 100℃. The rapid cooling effect is poor, failing to achieve the desired cooling effect and affecting production. When returned to the acid regeneration system, the large dilution significantly reduces the chloride ion content in the solution, rendering it unusable as pickling hydrochloric acid. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a cold-rolled acid regeneration sludge co-processing device and method, which directly achieves high-proportion decomposition of chloride ions in the sludge through pyrolysis without water washing, and treats and utilizes the decomposed chlorine-containing gas, thereby achieving sludge reduction and high-quality utilization.

[0006] To achieve the above objectives, the cold-rolled acid regeneration and impurity removal sludge co-processing device designed in this invention includes a roasting furnace. The upper feed inlet of the roasting furnace is connected to a hopper via a crusher, and the lower discharge outlet is connected to a receiving hopper. The air inlet of the roasting furnace is connected to a hot air furnace, and the air outlet is connected to a dust collector bag. The outlet of the dust collector bag is connected to an acid regeneration chlorine-containing gas treatment and utilization system.

[0007] Preferably, the air inlet of the hot air furnace is connected to a natural gas pipeline via a flow meter and a gas valve, the hot air furnace is connected to a fan, and the receiving hopper is connected to the dust collector bag.

[0008] Preferably, the outlet of the acid regeneration chlorine-containing gas treatment and utilization system is sequentially connected to a spray dust removal system and a chimney.

[0009] Preferably, the roasting furnace is divided into a high-temperature zone and a cooling zone, with the temperature in the high-temperature zone being 500–600°C.

[0010] Preferably, the high-temperature zone is made of biaxial stainless steel or titanium alloy, and the cooling zone is made of ceramic.

[0011] A treatment method for a cold-rolled acid regeneration sludge co-treatment device involves crushing the sludge obtained after removing impurities from the pickling waste liquid and transporting it to the roasting furnace for roasting. The chlorine-containing gas generated during roasting is transported to the acid regeneration chlorine-containing gas treatment and utilization system, and the Fe2O3 generated during roasting is transported to the receiving silo. After solid pelletizing, it is transported to the converter for steelmaking.

[0012] Preferably, the sludge obtained after removing impurities from the pickling waste liquid contains 45-60% iron and 13-33% chlorine on a dry basis.

[0013] Preferably, the crusher is a double-screw conveyor, which crushes the sludge during the conveying process to a particle size of less than 20mm.

[0014] Preferably, the sludge is arranged with a thickness of ≤200mm when roasting in the roasting furnace.

[0015] Preferably, the roasting furnace is divided into a high-temperature zone and a cooling zone. The temperature in the high-temperature zone of the roasting furnace is 500-600℃, the sludge residence time is 10-20 minutes, air is introduced during the roasting process, and then the sludge enters the cooling zone and is discharged after the temperature drops to 80-120℃.

[0016] In this invention, the reaction principle of the calcination process is as follows:

[0017] 2Fe(OH)3(s)=Fe2O3(s)+3H2O(g)

[0018] 2FeOOH(s)==Fe2O3(s)=+H2O(g)

[0019] 12FeCl2(s)+3O2(g)=2Fe2O3(s)+8FeCl3(s)

[0020] 4FeCl2(s)+4O2(g)+3H2O(g)=2Fe2O3(s)+4HCl(g)

[0021] 2FeCl3(s)+3H2O(g)=Fe2O3(s)+6HCl(g)

[0022] 4FeCl3(s)+3O2(g)=2Fe2O3(s)+6Cl2(g)

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. By controlling the pretreatment of sludge crushing, roasting thickness, temperature and time, the separation rate of substances with different utilization pathways in the sludge is high, 99.9% of chloride ions in the sludge are separated, and the sludge volume is reduced by about 50%.

[0025] 2. The chlorine-containing gas generated during roasting is used in conjunction with existing chlorine-containing gas treatment and utilization processes at the source of sludge generation for resource utilization. This enables the direct utilization of chlorine-containing substances through acid washing and thorough treatment of tail gas, achieving a residual solid content of Fe2O3 ≥ 88%, chlorine ≤ 0.1%, and 100% converter utilization.

[0026] 3. The sludge is directly roasted without being washed with water, which does not increase the amount of waste to be disposed of;

[0027] 4. The solids produced by roasting have a high content of valuable elements and great utilization value. Applying them to sintering or blast furnaces would consume more coal resources for iron oxide reduction. Applying them to converter steelmaking is more reasonable.

[0028] 5. The process is short, occupies a small area, has a high recycling rate, and is thoroughly disposed of. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the cold-rolled acid regeneration and impurity removal sludge co-processing device of the present invention;

[0030] Figure 2 This is a schematic diagram illustrating the principle of using the present invention for waste liquid treatment.

[0031] The components in the diagram are labeled as follows:

[0032] 1. Roasting furnace; 2. Crusher; 3. Feeding bin; 4. Hot air furnace; 5. Dust collector bag; 6. Acid regeneration chlorine-containing gas treatment and utilization system; 7. Flow meter; 8. Gas valve; 9. Fan; 10. Spray dust removal system; 11. Chimney; 12. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0034] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] like Figure 1 As shown, a cold-rolled acid regeneration and impurity removal sludge co-processing device includes a roasting furnace 1. The upper feed inlet of the roasting furnace 1 is connected to a hopper 3 via a crusher 2, and the lower discharge outlet is connected to a receiving hopper 4. The air inlet of the roasting furnace 1 is connected to a hot air furnace 5, and the air outlet is connected to a dust collector bag 6. The outlet of the dust collector bag 6 is connected to an acid regeneration chlorine-containing gas treatment and utilization system 7.

[0037] The hot air furnace 5 has an air inlet connected to a natural gas pipeline via a flow meter 8 and a gas valve 9. The hot air furnace 5 is also connected to a blower 10, and the receiving hopper 4 is connected to a dust collector bag 6.

[0038] The acid regeneration chlorine-containing gas treatment and utilization system 7 in this embodiment utilizes an existing process at the source of acid regeneration sludge removal. The main equipment includes a pre-concentration tower, an absorption tower, and a scrubbing tower. Its primary purpose is to absorb chlorine-containing gas from the gas through liquid absorption and concentrate the liquid to increase the HCl content, enabling direct acid washing and utilization of the liquid while ensuring the exhaust gas meets emission standards. In this embodiment, the outlet of the acid regeneration chlorine-containing gas treatment and utilization system 7 is sequentially connected to a spray dust removal system 11 and a chimney 12.

[0039] In addition, in this embodiment, the roasting furnace 1 is divided into a high-temperature zone and a cooling zone. The temperature of the high-temperature zone is 500-600°C and the material of the high-temperature zone is double-sided stainless steel or titanium alloy. The cooling zone is in direct contact with the sludge and the material is ceramic.

[0040] In this embodiment, the cold-rolled acid regeneration sludge co-processing device is used. After the pickling waste liquid is separated to remove impurities, the sludge obtained is crushed and transported to the roasting furnace 1 for roasting. The sludge obtained after separating impurities from the pickling waste liquid contains 45-60% iron and 13-33% chlorine on a dry basis. The crusher 2 is a double-screw conveyor, which crushes the sludge during the conveying process to a particle size of less than 20mm. When the sludge is roasted in the roasting furnace 1, the thickness of the arrangement is ≤200mm. The roasting furnace 1 is divided into a high-temperature zone and a cooling zone. The temperature in the high-temperature zone of the roasting furnace 1 is 500-600℃, and the sludge residence time is 10-20min. Air is introduced during the roasting process, and then the sludge enters the cooling zone. After being cooled to 80-120℃, the sludge is discharged. The chlorine-containing gas generated during roasting is transported to the acid regeneration chlorine-containing gas treatment and utilization system 7, and the Fe2O3 generated during roasting is transported to the receiving hopper 4. After solid pelletizing, it is transported to the converter for steelmaking.

[0041] Example 1:

[0042] 1) Start the roasting furnace 1 and its supporting equipment such as air intake, ignition, and exhaust, and heat it until the temperature in the high-temperature zone inside the furnace reaches 580℃;

[0043] 2) Sludge with a water content of 45.68%, a TFe content (dry basis) of 45.92%, and a chlorine content (dry basis) of 25.64% is conveyed by a double-screw conveyor and crushed to a particle size of less than 20mm into the roasting furnace 1. The rotation speed of the roasting furnace 1 is adjusted so that the thickness of the sludge in the furnace does not exceed 145mm.

[0044] 3) After being roasted in a high-temperature zone of 500℃ for 20 minutes, the sludge enters the cooling zone and is discharged when the temperature reaches 80℃. The roasted sludge has an Fe2O3 content of 88.22% and a chlorine content of 0.09%.

[0045] 4) The sludge is metered through receiving hopper 4, and after being briquetized with binder at a ratio of 98:2, it is transported to the converter for steelmaking as scrap steel.

[0046] Example 2:

[0047] 1) Start the roasting furnace 1 and its supporting equipment such as air intake, ignition, and exhaust, and heat it until the temperature in the high-temperature zone inside the furnace reaches 590℃.

[0048] 2) Sludge with a water content of 52.48%, a TFe content (dry basis) of 51.36%, and a chlorine content (dry basis) of 18.76% is conveyed by a double-screw conveyor and crushed to a particle size of less than 20mm into the roasting furnace 1. The speed of the roasting furnace 1 is adjusted so that the thickness of the sludge in the furnace does not exceed 160mm.

[0049] 3) After being roasted in a high-temperature zone of 560℃ for 16 minutes, the sludge enters the cooling zone and is discharged after the temperature reaches 100℃. The roasted sludge has an Fe2O3 content of 90.31% and a chlorine content of 0.07%.

[0050] 4) The sludge is metered through receiving hopper 4, and after being briquetized with binder at a ratio of 96:4, it is transported to the converter for steelmaking as scrap steel.

[0051] Example 3:

[0052] 1) Start the roasting furnace 1 and its supporting equipment such as air intake, ignition, and exhaust, and heat it until the temperature in the high-temperature zone inside the furnace reaches 600℃;

[0053] 2) Sludge with a water content of 48.69%, a TFe content (dry basis) of 49.64%, and a chlorine content (dry basis) of 23.82% is conveyed by a double-screw conveyor and crushed to a particle size of less than 20mm into the roasting furnace 1. The rotation speed of the roasting furnace 1 is adjusted so that the thickness of the sludge in the furnace does not exceed 200mm.

[0054] 3) After being roasted in a high-temperature zone of 600℃ for 10 minutes, the sludge enters the cooling zone and is discharged when the temperature reaches 120℃. The roasted sludge has an Fe2O3 content of 93.09% and a chlorine content of 0.03%.

[0055] 4) The sludge is metered through receiving hopper 4, and after being briquetized with binder at a ratio of 97:3, it is transported to the converter for steelmaking as scrap steel.

[0056] like Figure 2 As shown, when treating waste liquid, the waste liquid is first acid-washed, and then impurities are removed and separated. The pure liquid is treated by existing acid regeneration process equipment, and the sludge is treated by the cold rolling acid regeneration impurity removal sludge co-treatment device and treatment method of the present invention. The chlorine-containing gas is transported to the existing acid regeneration chlorine-containing gas treatment and utilization system 7 for treatment.

[0057] This invention relates to a cold-rolled acid regeneration sludge co-processing device and method. By controlling sludge crushing pretreatment, roasting thickness, temperature, and time, it achieves a high separation rate of substances from different utilization pathways within the sludge, resulting in 99.9% chloride ion separation and a sludge reduction of approximately 50%. The chlorine-containing gas generated during roasting is co-utilized with existing chlorine-containing gas treatment and utilization processes at the sludge source, enabling direct utilization of chlorine-containing substances through acid washing and thorough treatment of tail gas. This achieves a residual solid content of ≥88% Fe2O3, ≤0.1% chlorine, and 100% converter utilization. The sludge is directly roasted without water washing, thus not increasing waste disposal volume. The solids generated during roasting have high valuable element content and significant utilization value. Applying them to sintering or blast furnaces would consume more coal resources for iron oxide reduction; applying them to converter steelmaking is more rational. The process is short, requires little floor space, has a high recycling rate, and provides thorough treatment.

[0058] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0059] The aspects disclosed in this specification and claims are merely examples, and therefore, this specification and claims are not limited to the details shown. In the foregoing description, detailed descriptions of relevant known functions or configurations have been omitted where it would unnecessarily obscure the focus of this specification and claims.

[0060] When using the terms “comprising,” “having,” and “including” as described in this specification, there may be another part or other part unless used, and the terms used are generally singular but may also be plural.

[0061] Finally, it should be noted that the above description is a further detailed explanation of the invention in conjunction with specific embodiments. It should not be considered that the specific implementation of the invention is limited to these descriptions. For those skilled in the art, any simple substitutions made without departing from the concept of the invention should be considered within the scope of protection of this invention. The above embodiments are merely representative examples of the invention. Obviously, the invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the invention should be considered within the scope of protection of this invention.

[0062] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of this specification to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims. Features of various embodiments of this invention may be combined or spliced ​​together in part or in whole, and may be implemented in various different configurations as will be fully understood by those skilled in the art. Embodiments of this invention may be implemented independently of each other or may be implemented together in an interdependent relationship.

[0063] For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should all be considered to fall within the protection scope of the present invention.

Claims

1. A co-processing device for cold-rolled acid regeneration and impurity removal sludge, characterized in that: The furnace includes a roasting furnace (1), the upper feed inlet of which is connected to a hopper (3) via a crusher (2), and the lower discharge outlet is connected to a receiving hopper (4). The air inlet of the roasting furnace (1) is connected to a hot air furnace (5), and the air outlet is connected to a dust collector bag (6). The outlet of the dust collector bag (6) is connected to an acid regeneration chlorine-containing gas treatment and utilization system (7). The air inlet of the hot air furnace (5) is connected to a natural gas pipeline via a flow meter (8) and a gas valve (9). The hot air furnace (5) is connected to a fan (10). The receiving hopper (4) is connected to the dust collector bag (6). The air outlet of the acid regeneration chlorine-containing gas treatment and utilization system (7) is connected in sequence to a spray dust removal system (11) and a chimney (12). The roasting furnace (1) is divided into a high-temperature zone and a cooling zone. The temperature of the high-temperature zone is 500~600℃. The material of the high-temperature zone is biaxial stainless steel or titanium alloy. The material of the cooling zone is ceramic.

2. A treatment method for sludge co-treatment device for cold-rolled acid regeneration and impurity removal as described in claim 1, characterized in that: The sludge obtained after removing impurities from the pickling waste liquid is crushed and transported to the roasting furnace (1) for roasting. The chlorine-containing gas generated during roasting is transported to the acid regeneration chlorine-containing gas treatment and utilization system (7). The Fe2O3 generated during roasting is transported to the receiving silo (4). After solid pelletizing, it is transported to the converter for steelmaking. The sludge obtained after removing impurities from the pickling waste liquid contains 45-60% iron and 13-33% chlorine on a dry basis. When the sludge is roasted in the roasting furnace (1), the thickness of the arrangement is ≤200mm. The roasting furnace (1) is divided into a high-temperature zone and a cooling zone. The temperature of the high-temperature zone in the roasting furnace (1) is 500-600℃, and the sludge residence time is 10-20min. Air is introduced during the roasting process, and then the sludge enters the cooling zone and is discharged after being cooled to 80-120℃. The crusher (2) is a double-screw conveyor, which crushes the sludge during the conveying process and crushes the sludge to a particle size of less than 20mm.

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