System and method for resource utilization of industrial waste salt

Abstract

The invention discloses a system and a method for resource utilization of industrial waste salt, in the system, a compatibility and feeding module is respectively connected with a melting detoxification module and a melting vitrification module, the melting detoxification module is connected with a flue gas treatment module and a refined salt separation module, and the melting vitrification module and the flue gas treatment module are respectively connected with the refined salt separation module; the compatibility and feeding module divides the waste salt entering a factory into A-type waste salt and B-type waste salt according to the content of inorganic impurities, the A-type waste salt is sent into the melting detoxification module, and the B-type waste salt is input into the melting vitrification module; the melting detoxification module and the melting vitrification module are used for treating A-type waste salt and B-type waste salt respectively, obtained crude salt is conveyed to the refining salt separation module, and flue gas is treated through the flue gas treatment module. According to the system and the method, through the compatibility and cooperative treatment of the feeding module, the melting detoxification module, the melting vitrification module, the flue gas treatment module and the refining salt separation module, efficient detoxification of industrial waste salt and resource utilization of salt and nitrate are achieved.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and resource recycling technology, and in particular to a system and method for the resource utilization of industrial waste salt. Background Technology

[0002] The efficient resource utilization of industrial waste salt is a key challenge restricting the green development of industries such as chemical and pharmaceutical manufacturing. Traditional landfill or incineration methods not only pose risks of organic residue, heavy metal migration, and secondary pollution, but also fail to achieve effective resource utilization. Current pyrolysis and hydrometallurgical processes are not well-suited for waste salt with complex compositions, especially those containing heavy metals and high impurities, making it difficult to simultaneously achieve the goals of harmlessness and resource utilization. Furthermore, they generally suffer from low salt separation efficiency and high energy consumption. Therefore, it is particularly necessary to develop an efficient and synergistic resource utilization system for industrial waste salt to achieve both harmlessness and resource utilization.

[0003] Currently, systems commonly used for industrial waste salt disposal, based on waste salt detoxification technology, mainly include incineration, pyrolysis, and rigid landfill.

[0004] Industrial waste salt incineration system: This is a treatment system centered on high-temperature oxidation of industrial waste salt. Its core principle is to completely oxidize and decompose the organic matter in the waste salt into harmless substances such as carbon dioxide and water at a high temperature of 800-1200℃. Simultaneously, an inorganic salt component, such as sodium chloride and sodium sulfate, is recovered using a crude salt refining module, thereby achieving waste salt reduction, harmlessness, and resource utilization. This system can deeply remove organic pollutants from waste salt and can handle single salt types or complex mixed salt systems. However, during the technical implementation process, challenges such as high molten salt volatilization, slagging, and equipment corrosion need to be overcome.

[0005] Industrial waste salt pyrolysis system: This system uses medium-high temperature (typically 400-800℃) thermochemical conversion under anaerobic or low-oxygen conditions as its core technology to treat industrial waste salt. Its core principle is to use thermal energy to break down the molecular structure of organic matter, causing it to decompose into small molecule gases such as CO and H2, pyrolysis oil, and solid carbon residue. Simultaneously, a crude salt refining module removes other impurities from inorganic salts (such as sodium chloride and sodium sulfate). This technology has advantages such as a mild treatment process and low salt volatilization. However, due to the relatively low treatment temperature, the organic matter removal efficiency is low, and detoxification is incomplete, limiting its application to simple and easily treated waste salts.

[0006] Rigid landfill system for industrial waste salt: This is a safe disposal method for highly toxic, high-salinity industrial waste salt. It constructs high-density, seepage-proof landfill units using reinforced concrete structures, employing a composite seepage-proof system including multi-layer high-density polyethylene (HDPE) membranes and bentonite mats, and is equipped with leachate collection and gas monitoring devices to ensure long-term isolation of heavy metals, organic pollutants, and other harmful substances in the waste salt, preventing pollution of soil and groundwater. While this technology boasts advantages such as structural stability and excellent seepage-proof performance, it suffers from high construction costs and large land occupation, and it only provides temporary storage for waste salt, not achieving its complete harmless treatment.

[0007] In summary, industrial waste salt incineration, pyrolysis, and rigid landfill systems all have certain shortcomings. Industrial waste salt incineration systems suffer from high molten salt volatilization, leading to slagging and equipment corrosion in subsequent flue gas treatment modules. Industrial waste salt pyrolysis systems suffer from low organic matter removal efficiency and incomplete detoxification, limiting their applicability to simple and easily treated waste salts. Industrial waste salt rigid landfill systems suffer from high construction costs, large land occupation, and the lack of proper waste salt treatment. With increasingly stringent environmental protection requirements, the disposal of industrial waste salt faces more stringent demands. Therefore, inventing a comprehensive, collaborative, and resource-based industrial waste salt disposal system is of significant practical importance. Summary of the Invention

[0008] The purpose of this invention is to provide a system and method for the resource utilization of industrial waste salt, so as to at least partially solve the above-mentioned problems of the prior art.

[0009] To achieve the above objectives, one aspect of the present invention provides a system for the resource utilization of industrial waste salt, comprising a compatibility and feeding module (1), a melting and detoxification module (2), a melting and vitrification module (3), a flue gas treatment module (4), and a refining and separating salt module (5). The compatibility and feeding module (1) is connected to the melting and detoxification module (2) and the melting and vitrification module (3), the melting and detoxification module (2) is connected to the flue gas treatment module (4) and the refining and separating salt module (5), and the melting and vitrification module (3) and the flue gas treatment module (4) are connected to the refining and separating salt module (5).

[0010] The compatibility and feeding module (1) divides the incoming waste salt into Class A waste salt and Class B waste salt according to the content of inorganic impurities. Class A waste salt is sent to the melting and detoxification module (2), and Class B waste salt is input into the melting and vitrification module (3).

[0011] The melting and detoxification module (2) includes a melting and detoxification furnace (21), a first gas distribution component (23), and a first molten salt crushing and cooling unit (25). The melting and detoxification furnace (21) performs melting and oxidation treatment on Class A waste salt to produce molten salt and first flue gas. The first flue gas is output to the flue gas treatment module (4). The gas distribution component (23) performs oxidation treatment on the molten salt. The first molten salt crushing and cooling unit (25) is used to crush and cool the molten salt after it has been treated by the gas distribution component (23) to obtain the first crude salt. The first crude salt is then input into the refining and separating salt module (5).

[0012] The molten vitrification module (3) includes a molten vitrification furnace (31), a second gas distribution assembly (33), a second molten salt crushing and cooling unit (35), and a glass body cold extraction unit (37). The molten vitrification furnace (31) performs molten oxidation treatment on the mixture of Class B waste salt and additives to produce molten salt, glass body, and second flue gas. The second flue gas is output to the flue gas treatment module (4). The second gas distribution assembly (33) performs oxidation treatment on the molten salt. The second molten salt crushing and cooling unit (35) is used to crush and cool the molten salt after it has been treated by the second gas distribution assembly (33) to obtain a second crude salt. The second crude salt is input into the refining and separating salt module (5). The glass body cold extraction unit (37) is used to discharge the glass body formed by inorganic impurities and additives.

[0013] The flue gas treatment module (4) receives the flue gas input from the melting detoxification module (2) and the melting vitrification module (3), and performs oxygen combustion treatment on the flue gas to ensure that the flue gas meets emission standards.

[0014] The refined salt separation module (5) receives the first crude salt input from the melting detoxification module (2) and the second crude salt input from the melting vitrification module (3), and performs separation and purification processing.

[0015] Preferably, the melting and detoxification module (2) further includes a first waste salt spreading unit (22) and a first heating component (24), wherein the first waste salt spreading unit (22) is used to add waste salt into the melting and detoxification furnace (21) and spread the waste salt evenly on the upper layer of the material level of the melting and detoxification furnace (21) so that the melting and detoxification furnace (21) maintains cold top operation; the first heating component (24) is used to provide a heat source for the melting and detoxification furnace (21);

[0016] The molten vitrification module (3) also includes a second waste salt feeding unit (32) and a second heating component (34). The second waste salt feeding unit (32) is used to add waste salt into the molten vitrification furnace (31) and spread the waste salt evenly on the upper layer of the material level of the molten vitrification furnace (31) so that the molten vitrification furnace (31) maintains cold top operation. The second heating component (34) is used to provide a heat source for the molten vitrification furnace (31).

[0017] Preferably, the molten vitrification module (3) includes a mixing unit (36) for adjusting the ratio of Class B waste salt and additives to meet the vitrification requirements of inorganic impurities in Class B waste salt.

[0018] Preferably, the mixing unit (36) is connected to the refining and separating module (5) to receive the sludge output from the refining and separating module (5) and adjust the ratio of sludge, Class B waste salt and additives to meet the vitrification requirements of inorganic impurities in Class B waste salt.

[0019] Preferably, the compatibility and feeding module (1) is used to select different waste salt raw materials for compatibility and mixing, so that the organic content in the waste salt entering the furnace is maintained at the preset conditions.

[0020] Preferably, the flue gas treatment module (4) includes a secondary combustion chamber (41), a waste heat recovery unit (42), a quench unit (43), a deacidification unit (44), and a denitrification unit (45);

[0021] Among them, the secondary combustion chamber (41) is used to treat the flue gas with oxygen-enriched combustion;

[0022] The waste heat recovery unit (42) is connected to the secondary combustion chamber (41), the quench unit (43) and the salt purification module (5). It reduces the temperature of the flue gas output from the secondary combustion chamber (41) and generates steam through heat exchange. The steam is output to the salt purification module (5) for use, and the cooled flue gas is output to the quench unit (43).

[0023] The quench unit (43) quenches the flue gas output from the waste heat recovery unit (42), outputs the salt-containing quench water to the refining and salt separation module (5), and outputs the flue gas from the quench outlet to the deacidification unit (44).

[0024] The deacidification unit (44) uses alkaline solution to deacidify the flue gas and remove acidic substances from the flue gas;

[0025] The denitrification unit (45) is connected to the deacidification unit (44) to perform denitrification treatment on the flue gas after deacidification.

[0026] Preferably, the refining and separating salt module (5) includes:

[0027] Salt-nitrate compatibility unit (51) is used to compatibility of crude salt with salt-nitrate ratio and to purify the mixture of first and second crude salt that meet compatibility conditions.

[0028] Preferably, the refining and separating salt module (5) includes:

[0029] The dissolution unit (52) is used to dissolve the crude salt input from the salt-nitrate compatibility unit (51) to obtain a crude salt solution;

[0030] The sedimentation and filtration unit (53) is connected to the dissolution unit (52) and the molten vitrification module (3) for sedimentation and filtration of crude salt solution. The precipitated sludge is output to the molten vitrification module (3), and the filtered crude salt solution is output to the separation and purification unit (54).

[0031] The separation and purification unit (54) is used to decompose the crude salt solution into sodium sulfate and sodium chloride products and purify them.

[0032] Preferably, the salt-to-nitrate ratio of crude salt is 1:1 to 9:1.

[0033] Another aspect of the present invention provides a method for the resource utilization of industrial waste salt, applied to the system for the resource utilization of industrial waste salt provided in the above aspects and any preferred embodiments, comprising:

[0034] Waste salt entering the plant is classified into Class A waste salt and Class B waste salt according to the content of inorganic impurities.

[0035] The Class A waste salt is processed using a melting detoxification furnace, which outputs the first crude salt and the first flue gas.

[0036] The waste salt of type B is processed using a melting vitrification furnace, and the output is a second crude salt, a second flue gas, and a glassy substance;

[0037] The first and second flue gases are subjected to oxygen-per-combustion treatment.

[0038] The first and second crude salts are mixed and then separated and purified.

[0039] Compared with the prior art, the present invention has at least the following advantages:

[0040] Through the synergistic processing of the feed unit module, melting and detoxification module, melting and vitrification module, flue gas treatment module, and refining and separating salt module, efficient detoxification of industrial waste salt and resource utilization of salt and nitrate are achieved.

[0041] The system achieves efficient and stable operation of the melting and detoxification module, the melting and vitrification module, and the flue gas treatment module by adjusting the organic matter content in the industrial waste salt at the front end, and achieves stable operation of the refining and separating module system by adjusting the salt-nitrate ratio in the crude salt at the back end. This enables the system to operate efficiently and stably for industrial waste salts with different components.

[0042] This invention reduces the amount of salt volatilization by coupling electric heating with cold top fabric, thereby reducing the risk of corrosion and blockage to the flue gas system, while improving the system's energy utilization efficiency. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structural principle of a system for the resource utilization of industrial waste salt provided in Embodiment 1 of the present invention.

[0044] Figure 2 for Figure 1 A schematic diagram of the structure and principle of the mixing and feeding module.

[0045] Figure 3 for Figure 1 A schematic diagram of the structural principle of the medium-melting detoxification module.

[0046] Figure 4 for Figure 1 A schematic diagram illustrating the structural principle of the intermediate melting vitrification module.

[0047] Figure 5 for Figure 1 A schematic diagram of the structural principle of the flue gas treatment module.

[0048] Figure 6 for Figure 1 A schematic diagram of the structural principle of the intermediate refining and salt separation module.

[0049] Figure 7 This is a schematic flowchart of a method for the resource utilization of industrial waste salt provided in Embodiment 2 of the present invention. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0052] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0053] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0054] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "sleeving" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, components, or parts. "Cold top operation" refers to a furnace where the heat source is placed at the bottom, and newly added material is spread evenly on top, with the material at the top having a lower temperature and the material at the bottom having a higher temperature. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] Example 1

[0057] Embodiment 1 of the present invention provides a system for the resource utilization of industrial waste salt, realizing the efficient detoxification and resource utilization of industrial waste salt. Figure 1 A schematic diagram of the system structure is shown, such as... Figure 1 As shown, the system for the resource utilization of industrial waste salt provided in this embodiment of the invention includes a compatibility and feeding unit module 1, a melting and detoxification module 2, a melting and vitrification module 3, a flue gas treatment module 4, and a refining and separating salt module 5.

[0058] The compatibility and feeding module 1 is connected to the melting detoxification module 2 and the melting vitrification module 3 respectively. The melting detoxification module 2 is connected to the flue gas treatment module 4 and the refining and salt separation module 5 respectively. The melting vitrification module 3 and the flue gas treatment module 4 are connected to the refining and salt separation module 5 respectively.

[0059] The compatibility and feeding module 1 classifies the incoming waste salt into Class A waste salt and Class B waste salt according to the content of inorganic impurities. Class A waste salt is sent to the melting and detoxification module 2, and Class B waste salt is sent to the melting and vitrification module 3.

[0060] The compatibility and feeding module can also select different waste salt raw materials for compatibility and mixing, so that the organic content in the waste salt entering the furnace is maintained at preset conditions.

[0061] In a preferred embodiment, reference Figure 2 As shown, the compatibility and feeding module 1 includes a multi-level monitoring unit 11, a classification and temporary storage unit 12, an unpacking and crushing unit 13, a compatibility and mixing unit 14, and a feeding unit 15. The compatibility and feeding module 1 is used to control the composition and weight of the industrial waste salt being processed.

[0062] The multi-level monitoring unit 11 can monitor the composition and weight of industrial waste salt at different stages from generation and transportation to arrival at the plant, obtaining reliable data on the incoming waste salt. The multi-level monitoring unit 11 can include monitoring of the generated waste salt components, the incoming components, and the feed components. Each level of monitoring includes waste salt component analysis such as TOC content analysis, calorific value analysis, mass spectrometry analysis, and X-ray fluorescence spectroscopy analysis. Based on the incoming waste salt data, the classification and temporary storage unit 12 classifies and temporarily stores the waste salt according to its composition. Based on the content of inorganic impurities, waste salt with fewer inorganic impurities is classified as Class A waste salt, and waste salt with more inorganic impurities is classified as Class B waste salt. The classification criteria can be flexibly set according to actual needs. For example, waste salt with inorganic impurities not exceeding 0.03% is Class A waste salt, and waste salt with inorganic impurities exceeding 0.03% is Class B waste salt. Inorganic impurities include heavy metals such as lead, chromium, and nickel.

[0063] Based on the production schedule and inventory data of waste salt, and in conjunction with the system operation schedule, the unpacking and crushing unit 13 and the blending unit 14 work together to unpack and crush specific waste salt ton bags. The blending unit 14 then blends the unpacked and crushed waste salt to ensure that the overall organic content of waste salts A and B entering the furnace remains stable, for example, within a fluctuation range of 3%-10%. The feeding unit 15 transports waste salts A and B to the melting and detoxification module 2 and the melting and vitrification module 3, respectively.

[0064] refer to Figure 3As shown, the melting and detoxification module 2 includes a melting and detoxification furnace 21, a first gas distribution component 23, and a first molten salt crushing and cooling unit 25. The melting and detoxification furnace 21 performs melting and oxidation treatment on Class A waste salt to produce molten salt and first flue gas, which is output to the flue gas treatment module 4. The gas distribution component 23 performs oxidation treatment on the molten salt. The first molten salt crushing and cooling unit 25 is used to crush and cool the molten salt after it has been treated by the gas distribution component 23 to obtain first coarse salt, which is then input into the refining and separating salt module 5.

[0065] In a preferred embodiment, the melting and detoxification module 2 further includes a first waste salt distribution unit 22 and a first heating component 24. The first waste salt distribution unit 22 includes components such as a drive device and a rotating rake, used to add waste salt into the melting and detoxification furnace 21, spreading the waste salt evenly on the upper layer of the furnace to maintain a cold top operation. The first heating component 24 provides a heat source for the melting and detoxification furnace 21. The purpose of spreading the salt evenly is to ensure uniform distribution. It is easy to understand that if the waste salt is unevenly distributed, melting can still be achieved, but the effect will be poor.

[0066] In one embodiment, the first waste salt feeding unit 22 uniformly adds industrial waste salt to the melting and detoxification furnace 21, so that the industrial waste salt is spread evenly on the upper layer of the material level in the melting and detoxification furnace 21, allowing the melting and detoxification furnace 21 to maintain cold top operation, reducing energy consumption and salt evaporation. The melting and detoxification furnace 21 provides a heat source through the first heating component 24, melting the waste salt while removing most of the organic matter. The molten waste salt undergoes deep detoxification treatment through the gas distribution component 23, completely removing the organic matter. After the organic matter is removed, the molten salt is crushed and cooled by the first molten salt crushing and cooling unit 25 to obtain powdered coarse salt. The resulting coarse salt is fed into the refining and separating salt module 5 for processing. The flue gas generated by the melting and detoxification furnace 21 in removing organic matter is transmitted to the flue gas treatment module 4 for processing. Preferably, the first heating component 24 uses electrojoule heating, medium frequency heating, or other methods as a heat source, which has the advantages of easy furnace temperature control, simple operation, and low salt evaporation. Preferably, the oxidant used in the first gas distribution component 23 is air or oxygen, which diffuses into the molten salt pool through the permeable bricks.

[0067] In one embodiment, after receiving Class A waste salt through the first waste salt feeding unit 22, the melting detoxification furnace 21 can preheat the waste salt to improve reaction efficiency and reduce energy consumption. Then, using a gas-fired and electrically assisted heating method, the Class A waste salt is heated to a higher temperature, allowing the organic pollutants to undergo a complete melting, oxidation, and detoxification reaction under high temperature and aerobic conditions through multi-stage combustion. Buffer plates and other structures are used to increase the melting residence time of the waste salt in the furnace, ensuring a complete reaction and producing high-purity molten salt, high-temperature steam, and flue gas. The molten salt, after water quenching and recrystallization, is transported to the first molten salt crushing and cooling unit 25. The high-temperature steam can flow back to the preheating zone of the melting detoxification furnace 21 to preheat new waste salt. The flue gas enters the flue gas treatment module 4 for processing.

[0068] refer to Figure 4 As shown, the molten vitrification module 3 includes a molten vitrification furnace 31, a second gas distribution assembly 33, a second molten salt crushing and cooling unit 35, and a glass body cold extraction unit 37. The molten vitrification furnace 31 performs molten oxidation treatment on a mixture of Class B waste salt and additives. The Class B waste salt is melted, and the additives and inorganic impurities react to form a glass body, generating a second flue gas (the "second" flue gas is used to distinguish it from the "first" flue gas generated by the molten detoxification furnace 2). The second flue gas is output to the flue gas treatment module 4. The second gas distribution assembly 33 oxidizes the molten salt. The second molten salt crushing and cooling unit 35 crushes and cools the molten salt processed by the second gas distribution assembly 33 to obtain a second crude salt, which is then input into the refining and separating salt module 5. The glass body cold extraction unit 37 discharges the glass body formed by inorganic impurities and additives.

[0069] In a preferred embodiment, the molten vitrification module 3 includes a mixing unit 36 ​​for adjusting the ratio of Class B waste salt and additives to meet the vitrification requirements of inorganic impurities in the Class B waste salt. The mixing unit 36 ​​can be connected to the refining and separating module 5, receiving the sludge output from the refining and separating module 5, and adjusting the ratio of sludge, Class B waste salt, and additives to meet the vitrification requirements of inorganic impurities in the Class B waste salt.

[0070] In one embodiment, after Class B waste salt enters the molten vitrification module 3, the waste salt, additives, and sludge from the refining and separating salt module 5 are mixed and blended by the mixing unit 36 ​​to ensure that the inorganic impurities are sufficient to meet the requirements for vitrification. The blended waste salt is then evenly added to the molten vitrification furnace 31 through the second waste salt distribution unit 32, ensuring that the waste salt is evenly distributed on the upper layer of the molten vitrification furnace 31, allowing the molten vitrification furnace 31 to maintain a cold top operation, reducing energy consumption and salt evaporation. The molten vitrification furnace 31 provides a heat source through the second heating component 34, melting the waste salt while removing most of the organic matter. The molten waste salt undergoes deep detoxification treatment through the second gas distribution component 33, completely removing the organic matter. After the organic matter is removed, the molten salt is crushed and cooled by the second molten salt crushing and cooling unit 35 to obtain powdered coarse salt. The resulting coarse salt is then transferred to the refining and separating salt module 5 for processing. The flue gas generated by the molten vitrification furnace 31 during organic matter removal is transferred to the flue gas treatment module 4 for treatment. The glassy substance formed by inorganic impurities and additives is discharged through the glassy substance cold extraction unit 37, thereby solidifying the inorganic impurities in industrial waste salt.

[0071] The second waste salt feeding unit 32 includes a driving device, a feeding device, etc., which is used to uniformly add waste salt into the molten glass furnace 31, so that the waste salt is spread evenly on the upper layer of the material level of the molten glass furnace 32, so that the molten glass furnace 32 maintains cold top operation, reduces energy consumption and reduces salt evaporation.

[0072] Preferably, the second heating component 34 uses electrojoule heating, medium-frequency heating, or other methods as a heat source, which has the advantages of easy furnace temperature control, simple operation, and low salt evaporation. Preferably, the oxidant used in the second gas distribution component 33 is air or oxygen, which diffuses into the molten salt pool through permeable bricks. The molten salt pool can be a device at the bottom of the molten vitrification furnace 31 for storing molten waste salt.

[0073] The flue gas treatment module 4 receives the flue gas input from the melting detoxification module 2 and the melting vitrification module 3, and performs oxygen combustion treatment on the flue gas to ensure that the flue gas meets emission standards.

[0074] In one implementation, reference Figure 5 As shown, the flue gas treatment module 4 includes a secondary combustion chamber 41, a waste heat recovery unit 42, a quench unit 43, a deacidification unit 44, and a denitrification unit 45;

[0075] Among them, the secondary combustion chamber 41 is used for oxygen-excessive combustion treatment of flue gas;

[0076] Waste heat recovery unit 42 is connected to secondary combustion chamber 41, quench unit 43 and refining salt separation module 5. It reduces the temperature of flue gas output from secondary combustion chamber 41 and generates steam through heat exchange. The steam is output to refining salt separation module 5 for utilization, and the cooled flue gas is output to quench unit 43.

[0077] The quench unit 43 quenches the flue gas output from the waste heat recovery unit 42, outputs the salt-containing quench water to the refining and salt separation module 5, and outputs the flue gas from the quench outlet to the deacidification unit 44.

[0078] The deacidification unit 44 uses alkaline solution to deacidify the flue gas, removing acidic substances from the flue gas;

[0079] The denitrification unit 45 is connected to the deacidification unit 44 to perform denitrification treatment on the flue gas after the deacidification treatment.

[0080] Among them, the waste heat recovery unit 42 is, for example, a heat exchanger, in which the boiler water exchanges heat with the high-temperature flue gas output from the secondary combustion chamber 41, and the generated steam can be sent to the refining and separating salt module 5 (e.g., sodium chloride MVR subunit).

[0081] In one embodiment, the flue gas generated by the melting detoxification module 2 and the melting vitrification module 3 enters the secondary combustion chamber 41 for oxygen-enriched combustion treatment. The combustion temperature exceeds 1100°C, and the residence time exceeds 2 seconds, ensuring the complete decomposition of organic matter in the flue gas. The high-temperature flue gas generated in the secondary combustion chamber 41 is cooled to above 500°C by the waste heat recovery unit 42, simultaneously generating steam. This steam can be utilized by the refining and salt separation module 5. Salt dust settled in the waste heat boiler can also be sent to the refining and salt separation module 5 for treatment. The flue gas exiting the waste heat recovery unit 42 enters the quenching unit 43 for further cooling, reducing the flue gas temperature to below 100°C within 1 second to prevent the formation of dioxins. The discharged saline quenching water is disposed of in the refining and salt separation module 5. The flue gas exiting the quenching unit 43 passes through the alkaline washing and deacidification unit 44 and the catalytic denitrification unit 45 to remove acidic pollutants from the flue gas, ensuring that the flue gas meets emission standards. The alkaline washing and deacidification unit 44 may include an alkaline solution tank through which the flue gas undergoes deacidification treatment. The catalytic denitrification unit 45 may include, for example, ammonia water, through which the flue gas undergoes denitrification treatment. The quenching unit 43 uses quenching water (i.e., industrial water) sprayed into the quencher through nozzles to cool the flue gas from above 500°C to below 100°C within 1 second. The quenching unit 43 may also utilize the alkaline solution in the alkaline solution tank of the alkaline washing and deacidification unit 44, spraying it together with the quenching water into the quencher through nozzles to further remove acidic gases from the flue gas while simultaneously achieving cooling.

[0082] The refined salt separation module 5 receives the first crude salt input from the melting detoxification module 2 and the second crude salt input from the melting vitrification module 3, and performs separation and purification processing.

[0083] In one implementation, reference Figure 6 As shown, the refined salt separation module 5 includes:

[0084] The dissolving unit 52 is used to dissolve the crude salt input from the salt-nitrate compatibility unit 51 to obtain a crude salt solution;

[0085] The sedimentation and filtration unit 53 is connected to the dissolution unit 52 and the molten vitrification module 3. It is used to precipitate and filter the crude salt solution, and output the precipitated sludge to the molten vitrification module 3 and the filtered crude salt solution to the separation and purification unit 54.

[0086] The separation and purification unit 54 is used to decompose the crude salt solution into sodium sulfate and sodium chloride products and then purify them.

[0087] The salt-to-nitrate ratio of crude salt is 1:1 to 9:1.

[0088] In one embodiment, the refined salt separation module 5 includes a salt-nitrate compatibility unit 51, a dissolution unit 52, a precipitation and filtration unit 53, and a separation and purification unit 54. The separation and purification unit 54 includes a cryogenic crystallization sub-unit 541, a nitrate recrystallization sub-unit 542, a nanofiltration sub-unit 543, and a sodium chloride MVR sub-unit 544. This module can separate the salt and nitrate produced by the system, realizing the productization and resource utilization of salt and nitrate.

[0089] In one embodiment, the crude salt produced by the melting detoxification module 2 and the melting vitrification module 3 is mixed in a salt-nitrate ratio-matching unit 51, and then sequentially enters the dissolution unit 52 and the precipitation and filtration unit 53. The sludge generated in the precipitation and filtration unit 53 is treated by the melting vitrification module 3. Subsequently, the salt passes through the cryogenic crystallization sub-unit 541, the nitrate recrystallization sub-unit 542, the nanofiltration sub-unit 543, and the sodium chloride MVR sub-unit 544 in the separation and purification unit 54 to achieve the separation and purification of sodium sulfate and sodium chloride, producing sodium sulfate and sodium chloride products, thus realizing the resource utilization of industrial waste salt.

[0090] Among them, the salt-nitrate compatibility unit 51 compatibility is based on the salt-nitrate ratio in the crude salt produced by the melting detoxification module 2 and the melting vitrification module 3, so as to reduce the fluctuation of the salt-nitrate ratio and ensure the stable operation of subsequent units.

[0091] The dissolving unit 52 is used to receive the material after it has been processed by the salt-nitrate compatibility unit 51 and dissolve it to convert the crude salt and other solid materials into a salt solution. This creates conditions for subsequent separation and purification operations such as precipitation, filtration, and crystallization, so that components such as salt and nitrate can be separated in the solution environment according to their respective characteristics.

[0092] The sedimentation and filtration unit 53 is used to precipitate and filter the salt solution produced by the dissolution unit 52. Sedimentation allows insoluble impurities in the solution (such as possible solid impurities like mud and sand, as well as some precipitates produced by reactions) to settle to the bottom of the container. Then, filtration (such as using filter screens, filter cloths, or other filter media) separates the precipitate from the solution, resulting in a relatively clear salt solution. Meanwhile, the sludge produced is transported to the molten vitrification module 3 for disposal, achieving reasonable treatment and reuse of impurities.

[0093] The cryo-crystallization subunit 541 is used to perform cryo-crystallization on the salt solution after it has been treated by the precipitation and filtration unit 53. By utilizing the difference in solubility of different substances at different temperatures, the temperature is lowered so that a certain component (such as sodium sulfate) in the solution reaches a supersaturated state and crystallizes out, thereby achieving the initial separation of this component from other components (such as sodium chloride) in the solution, preparing for further purification in subsequent units such as nitrate recrystallization and nanofiltration.

[0094] Nitrate recrystallization subunit 542 is used to recrystallize nitrates (such as sodium sulfate crystals) that have crystallized out in the freeze crystallization unit 541. Through the process of redissolving and crystallizing, impurities that may be contained in the nitrate crystals are removed, the purity of the nitrate products is improved, and high-purity sodium sulfate and other nitrate products are obtained, thereby improving the product quality of industrial waste salt resource utilization.

[0095] Nanofiltration subunit 543 is used to perform nanofiltration on the salt solution processed by the previous unit. Utilizing the selective permeability of the nanofiltration membrane, the components in the salt solution are further separated based on differences in the size, charge, etc., of different ions or molecules. This allows for fine separation of ions in the solution, providing a purer raw material solution for the subsequent sodium chloride MVR subunit 544 to prepare high-purity sodium chloride products, thereby improving the quality and purity of the sodium chloride products.

[0096] The sodium chloride MVR subunit 544 is used to perform MVR (mechanical vapor recompression) evaporation and crystallization on the sodium chloride-containing solution after treatment by the nanofiltration subunit 543. Through MVR technology, the water in the solution is evaporated, causing the sodium chloride to reach a supersaturated state and crystallize out, ultimately yielding a high-purity sodium chloride product. This realizes the resource utilization of sodium chloride in industrial waste salt, producing recyclable sodium chloride product, and completing an important step in the resource utilization of industrial waste salt.

[0097] In one embodiment, the salt-nitrate blending unit 51 mixes the first and second crude salts produced over a period of time, ensuring a stable mass ratio of sodium chloride to sodium sulfate in the crude salt entering the crude salt refining module 5, which is beneficial for efficient system operation. The dissolving unit 52 places the crude salt into a salt pool to obtain near-saturated brine. The precipitation and filtration unit 53 initially removes impurities such as calcium, magnesium, and heavy metals from the brine by adding alkali and flocculants. Some of these impurities come from the melting and detoxification module 2, while a small amount also exists from the molten salt flowing out of the melting and vitrification module 3 and dust particles carried out of the flue gas. The cryogenic crystallization subunit 541 includes a compressor and refrigerant, which cools the brine. Because sodium sulfate has near-zero solubility at low temperatures, it can precipitate, leaving mainly sodium chloride solution in the brine. The nitrate recrystallization subunit 542 includes devices for dissolving and evaporating sodium sulfate. The sodium sulfate precipitated in the cryogenic crystallization subunit 541 contains 10 molecules of water of crystallization and cannot be used as a product; it needs to be dissolved and then evaporated to obtain anhydrous sodium sulfate. Nanofiltration subunit 543 includes a nanofiltration membrane that allows monovalent chloride ions to pass through while preventing divalent sulfate ions from passing through. This separates the small amount of sulfate ions (i.e., sodium sulfate) remaining in the brine after freeze crystallization, thereby purifying the sodium chloride in the brine. Sodium chloride MVR (Mechanical Vapor Recompression) subunit 544 is a commonly used evaporation crystallization device with high evaporation energy utilization, yielding sodium chloride product.

[0098] The system for the resource utilization of industrial waste salt provided in this invention achieves efficient detoxification and resource utilization of salt and nitrates through the coordinated processing of the feeding unit module, melting and detoxification module, melting and vitrification module, flue gas treatment module, and refining and separating salt module. The system achieves efficient and stable operation of the melting and detoxification module, melting and vitrification module, and flue gas treatment module by adjusting the organic matter content in the industrial waste salt at the front end, and stable operation of the refining and separating salt module system by adjusting the salt-nitrate ratio in the crude salt at the back end. This enables efficient and stable operation of the system for industrial waste salts with different components. The coupling of electric heating and cold top material reduces the volatilization of salt, thereby reducing the risk of corrosion and blockage in the flue gas system and improving the system's energy utilization efficiency. By adopting the system provided in this invention, the problems of incomplete removal of organic pollutants from industrial waste salt and the vitrification of inorganic impurities (heavy metal ions, calcium, magnesium, etc.) in industrial waste salt can be solved; the problem of coordinated treatment of waste generated by different modules of the industrial waste salt treatment system (such as salt dust, saline wastewater, sludge, etc.) can also be solved.

[0099] Example 2

[0100] Based on the same technical concept as the system for industrial waste salt resource utilization provided in Example 1, this embodiment of the invention provides a method for industrial waste salt resource utilization. Figure 7 A flowchart illustrating this method is shown, as follows: Figure 7 As shown, it includes:

[0101] Step 701: Based on the content of inorganic impurities, the incoming waste salt is divided into Class A waste salt and Class B waste salt;

[0102] Step 702: The Class A waste salt is processed using a melting detoxification furnace to output the first crude salt and the first flue gas;

[0103] Step 703: The waste salt of type B is processed using a melting vitrification furnace to output the second crude salt, the second flue gas, and the glass body;

[0104] Step 704: Perform oxygen-permeable combustion treatment on the first and second flue gas;

[0105] Step 705: Mix the first crude salt and the second crude salt and perform separation and purification treatment.

[0106] The specific implementation of each of the above steps can be found in Embodiment 1 and its various implementation methods, and will not be repeated here.

[0107] By employing the method for resource utilization of industrial waste salt provided in this invention, the efficient detoxification and resource utilization of salt and nitrate are achieved through the coordinated operation of steps such as formulation and feeding, melting detoxification, melting vitrification, flue gas treatment, and refining and separating salt. The efficient and stable operation of melting detoxification, melting vitrification, and flue gas treatment is achieved by front-end formulation of the organic matter content in the industrial waste salt, while the stable system of refining and separating salt is achieved by back-end formulation of the salt-to-nitrate ratio in the crude salt. This enables efficient and stable system operation for industrial waste salts with different components. Furthermore, the coupling of electric heating and cold top covering reduces the volatilization of salt, thereby reducing the risk of corrosion and blockage in the flue gas system and improving the system's energy utilization efficiency.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for the resource utilization of industrial waste salt, characterized in that, It includes a compatibility and feeding module (1), a melting and detoxification module (2), a melting and vitrification module (3), a flue gas treatment module (4), and a refining and salt separation module (5). The compatibility and feeding module (1) is connected to the melting and detoxification module (2) and the melting and vitrification module (3), respectively. The melting and detoxification module (2) is connected to the flue gas treatment module (4) and the refining and salt separation module (5), respectively. The melting and vitrification module (3) and the flue gas treatment module (4) are connected to the refining and salt separation module (5). The compatibility and feeding module (1) divides the incoming waste salt into Class A waste salt and Class B waste salt according to the content of inorganic impurities. Class A waste salt is sent to the melting and detoxification module (2), and Class B waste salt is input into the melting and vitrification module (3). The melting and detoxification module (2) includes a melting and detoxification furnace (21), a first gas distribution component (23), and a first molten salt crushing and cooling unit (25). The melting and detoxification furnace (21) performs melting and oxidation treatment on Class A waste salt to produce molten salt and first flue gas. The first flue gas is output to the flue gas treatment module (4). The gas distribution component (23) performs oxidation treatment on the molten salt. The first molten salt crushing and cooling unit (25) is used to crush and cool the molten salt after it has been treated by the gas distribution component (23) to obtain the first crude salt. The first crude salt is then input into the refining and separating salt module (5). The molten vitrification module (3) includes a molten vitrification furnace (31), a second gas distribution assembly (33), a second molten salt crushing and cooling unit (35), and a glass body cold extraction unit (37). The molten vitrification furnace (31) performs molten oxidation treatment on the mixture of Class B waste salt and additives to produce molten salt, glass body, and second flue gas. The second flue gas is output to the flue gas treatment module (4). The second gas distribution assembly (33) performs oxidation treatment on the molten salt. The second molten salt crushing and cooling unit (35) is used to crush and cool the molten salt after it has been treated by the second gas distribution assembly (33) to obtain a second crude salt. The second crude salt is input into the refining and separating salt module (5). The glass body cold extraction unit (37) is used to discharge the glass body formed by inorganic impurities and additives. The flue gas treatment module (4) receives the flue gas input from the melting detoxification module (2) and the melting vitrification module (3), and performs oxygen combustion treatment on the flue gas to ensure that the flue gas meets emission standards. The refined salt separation module (5) receives the first crude salt input from the melting detoxification module (2) and the second crude salt input from the melting vitrification module (3), and performs separation and purification processing.

2. The industrial waste salt resource utilization system according to claim 1, characterized in that, The melting and detoxification module (2) also includes a first waste salt spreading unit (22) and a first heating component (24). The first waste salt spreading unit (22) is used to add waste salt into the melting and detoxification furnace (21) and spread the waste salt evenly on the upper layer of the material level of the melting and detoxification furnace (21) so that the melting and detoxification furnace (21) maintains cold top operation. The first heating component (24) is used to provide a heat source for the melting and detoxification furnace (21). The molten vitrification module (3) also includes a second waste salt feeding unit (32) and a second heating component (34). The second waste salt feeding unit (32) is used to add waste salt into the molten vitrification furnace (31) and spread the waste salt evenly on the upper layer of the material level of the molten vitrification furnace (31) so that the molten vitrification furnace (31) maintains cold top operation. The second heating component (34) is used to provide a heat source for the molten vitrification furnace (31).

3. The industrial waste salt resource utilization system according to claim 1 or 2, characterized in that, The molten vitrification module (3) includes a mixing unit (36) for adjusting the ratio of Class B waste salt and additives to meet the vitrification requirements of inorganic impurities in Class B waste salt.

4. The industrial waste salt resource utilization system according to claim 3, characterized in that, The mixing unit (36) is connected to the refining and separating module (5) to receive the sludge output from the refining and separating module (5) and adjust the ratio of sludge, Class B waste salt and additives to meet the vitrification requirements of inorganic impurities in Class B waste salt.

5. The industrial waste salt resource utilization system according to claim 1 or 2, characterized in that, The compatibility and feeding module (1) is used to select different waste salt raw materials for compatibility and mixing, so that the organic content in the waste salt entering the furnace is maintained at the preset conditions.

6. The industrial waste salt resource utilization system according to claim 1 or 2, characterized in that, The flue gas treatment module (4) includes a secondary combustion chamber (41), a waste heat recovery unit (42), a quench unit (43), a deacidification unit (44), and a denitrification unit (45); Among them, the secondary combustion chamber (41) is used to treat the flue gas with oxygen-enriched combustion; The waste heat recovery unit (42) is connected to the secondary combustion chamber (41), the quench unit (43) and the salt purification module (5). It reduces the temperature of the flue gas output from the secondary combustion chamber (41) and generates steam through heat exchange. The steam is output to the salt purification module (5) for use, and the cooled flue gas is output to the quench unit (43). The quench unit (43) quenches the flue gas output from the waste heat recovery unit (42), outputs the salt-containing quench water to the refining and salt separation module (5), and outputs the flue gas from the quench outlet to the deacidification unit (44). The deacidification unit (44) uses alkaline solution to deacidify the flue gas and remove acidic substances from the flue gas; The denitrification unit (45) is connected to the deacidification unit (44) to perform denitrification treatment on the flue gas after deacidification.

7. The industrial waste salt resource utilization system according to claim 1 or 2, characterized in that, The refining and separating salt module (5) includes: Salt-nitrate compatibility unit (51) is used to compatibility of crude salt with salt-nitrate ratio and to purify the mixture of first and second crude salt that meet compatibility conditions.

8. The industrial waste salt resource utilization system according to claim 7, characterized in that, The refining and separating salt module (5) includes: The dissolution unit (52) is used to dissolve the crude salt input from the salt-nitrate compatibility unit (51) to obtain a crude salt solution; The sedimentation and filtration unit (53) is connected to the dissolution unit (52) and the molten vitrification module (3) for sedimentation and filtration of crude salt solution. The precipitated sludge is output to the molten vitrification module (3), and the filtered crude salt solution is output to the separation and purification unit (54). The separation and purification unit (54) is used to decompose the crude salt solution into sodium sulfate and sodium chloride products and purify them.

9. The industrial waste salt resource utilization system according to claim 7, characterized in that, The salt-to-nitrate ratio of crude salt is 1:1 to 9:

1.

10. A method for the resource utilization of industrial waste salt, characterized in that, The system applied according to any one of claims 1-9 comprises: Waste salt entering the plant is classified into Class A waste salt and Class B waste salt according to the content of inorganic impurities. The Class A waste salt is processed using a melting detoxification furnace, which outputs the first crude salt and the first flue gas. The waste salt of type B is processed using a melting vitrification furnace, and the output is a second crude salt, a second flue gas, and a glassy substance; The first and second flue gases are subjected to oxygen-per-combustion treatment. The first and second crude salts are mixed and then separated and purified.

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