An industrial phosphogypsum and organic waste salt resource utilization system, method and application

Abstract

The application provides a resource utilization system and method and application of industrial phosphogypsum and organic waste salt, and the resource utilization method comprises the following steps: mixing, granulating, calcining, water immersion treating and post-treating: industrial phosphogypsum, organic waste salt and a reducing agent are mixed and granulated to obtain a mixture; the mixture is subjected to calcining treatment to obtain a calcined product and a calcined tail gas; the calcined product is subjected to water immersion treatment to obtain a precipitate and a salt-containing solution, and then the precipitate and the salt-containing solution are respectively subjected to post-treatment to obtain a recovery product. The organic waste salt has the characteristics of molten salt at high temperature, the decomposition temperature of the phosphogypsum is reduced, the decomposition efficiency of the phosphogypsum is improved, the conversion rate of the phosphogypsum to calcium sulfide reaches more than 98%, and the organic matter in the organic waste salt is removed, and the removal rate of the organic matter reaches more than 99.5%. The method not only realizes the collaborative disposal and resource utilization of the industrial phosphogypsum and the organic waste salt, but also is environmentally friendly, safe and efficient, and is a green and clean resource utilization process.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a resource utilization system, method and application of industrial phosphogypsum and organic waste salt. Background Technology

[0002] Phosphogypsum is a solid byproduct of wet-process phosphoric acid production. Its composition is complex, primarily consisting of CaSO4·2H2O, along with residual phosphoric acid, fluorides, and acid-insoluble substances. The presence of fluorine and phosphorus has the greatest impact on the resource utilization of phosphogypsum. my country discharges 80 million tons annually, with stockpiles exceeding 600 million tons, while global stockpiles have reached over 6 billion tons. Currently, comprehensive utilization methods for phosphogypsum include its use in the production of building materials such as bricks or slabs, cement retarders, and soil conditioners, but the average utilization rate is only around 10%. Domestically and internationally, the common methods for disposing of phosphogypsum are landfilling or dumping it into the sea. These methods not only occupy large amounts of land and cause serious resource waste but also pollute water and land resources. Therefore, the comprehensive utilization of phosphogypsum remains a global challenge.

[0003] Large quantities of industrial waste salt are produced as byproducts in various chemical industries, including pharmaceuticals, pesticides, organic chemicals, fine chemicals, and coal chemicals. For example, in the pesticide industry, approximately one ton of organic waste salt is generated for every ton of pesticide produced. The main component of this waste salt is NaCl, along with complex organic compounds such as halogenated hydrocarbons and benzene derivatives. These organic compounds have boiling points and thermal decomposition temperatures ranging from 200 to 600°C and exhibit toxicity, bioaccumulation, and environmental persistence. Therefore, industrial waste salt was included in the "National Hazardous Waste List" in 2016 and classified as hazardous waste.

[0004] Therefore, the harmless treatment and resource utilization of organic waste salts are urgent needs for the sustainable development of the industry. Current disposal methods include ocean dumping, landfilling, and pyrolysis. The first two methods rely on nature's self-purification ability to treat toxic and harmful substances, which will inevitably cause serious damage to the environment in the long run. Although pyrolysis has disadvantages such as agglomeration, caking, and melting, it has high processing efficiency, high product purity, and more thorough removal of organic matter, making it a more practical treatment method at present.

[0005] CN101428767A discloses a process for producing calcium sulfide using phosphogypsum or other gypsum. The process involves mixing and grinding gypsum and coal in a molar ratio of 1:2 to 4, adding water to form pellets or blocks, and then calcining them in a rotary kiln at 800 to 1100°C for 0.5 to 1.5 hours to obtain calcium sulfide product. The conversion rate can reach over 95%. However, the process is cumbersome, complicated to operate, and energy-intensive, making it difficult to implement.

[0006] CN112250471A discloses a method for vitrifying industrial phosphogypsum and waste salt residue. This method includes drying, pulverizing, and mixing the phosphogypsum and waste salt residue, compounding additives to obtain a ceramic blank, and then drying and sintering it to obtain the ceramic material. While the method has a simple process, it suffers from long calcination time, high energy consumption, high processing costs, and low utilization rate.

[0007] CN107990320A discloses a method and system for co-treating organic waste salt and high-salinity organic wastewater in a cement kiln. Utilizing the technological characteristics of cement kilns, it employs the waste heat from flue gas during cement production, combining low-temperature dehydration and concentration with high-temperature incineration to achieve two-stage incineration of organic waste salt and high-salinity organic wastewater to obtain clean industrial salt. However, this process suffers from drawbacks such as equipment agglomeration, caking, and difficulty in separating molten salt.

[0008] As can be seen from the existing technologies above, it is of great significance to develop a harmless, green and clean process for disposing of solid wastes such as phosphogypsum and organic waste salts, which can effectively transform them into reusable resources while reducing environmental pollution. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a system, method, and application for the resource utilization of industrial phosphogypsum and organic waste salt. This invention utilizes the molten salt properties of organic waste salt at high temperatures to lower the decomposition temperature of phosphogypsum, thereby increasing its decomposition efficiency and achieving a conversion rate of over 98% for phosphogypsum to calcium sulfide. Simultaneously, it removes organic matter from the organic waste salt, achieving a removal rate of over 99.5%. This method not only achieves the co-processing and resource utilization of industrial phosphogypsum and organic waste salt but is also environmentally friendly, safe, and efficient—a green and clean resource utilization process.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0012] (1) Mix and granulate industrial phosphogypsum, organic waste salt and reducing agent to obtain a mixture;

[0013] (2) The mixture is calcined to obtain calcined products and calcined tail gas;

[0014] (3) The calcined product is subjected to water immersion treatment to obtain a precipitate and a salt solution. The precipitate and the salt solution are then post-treated to obtain the recovered product.

[0015] This invention utilizes the molten salt properties of organic waste salt at high temperatures to lower the decomposition temperature of phosphogypsum and improve its decomposition efficiency, enabling a conversion rate of phosphogypsum to calcium sulfide of over 98%. Simultaneously, it achieves the removal of organic matter from the organic waste salt, with a removal rate exceeding 99.5%. This method not only realizes the co-processing and resource utilization of industrial phosphogypsum and organic waste salt, but is also environmentally friendly, safe, and efficient, representing a green and clean resource utilization process.

[0016] As a preferred technical solution of the present invention, the organic waste salt in step (1) includes sodium chloride.

[0017] Preferably, the reducing agent includes any one or a combination of at least two of pulverized coal, coke powder, or biomass pellets.

[0018] Preferably, in the mixture, the mass ratio of industrial phosphogypsum, organic waste salt, and reducing agent is 100:(15-30):(10-25), wherein the organic waste salt is selected within the range of "15-30", for example, 15, 20, 25, or 30, and the reducing agent is selected within the range of "10-25", for example, 10, 15, 20, or 25. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the particle size of the mixture in step (1) is 1-5 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] As a preferred technical solution of the present invention, before mixing the industrial phosphogypsum, organic waste salt and reducing agent in step (1), the industrial phosphogypsum, organic waste salt and reducing agent are pretreated respectively.

[0021] Preferably, the pretreatment of the industrial phosphogypsum includes drying and dehydration.

[0022] Preferably, the drying and dehydration temperature is 150-300℃, for example, it can be 150℃, 180℃, 200℃, 230℃, 250℃, 280℃ or 300℃, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the pretreatment method for the organic waste salt includes low-temperature drying.

[0024] Preferably, the low-temperature drying temperature is 50-100℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃, 95℃ or 100℃, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pretreatment of the reducing agent includes crushing and sieving.

[0026] Preferably, the reducing agent after pulverization and sieving has a mesh size of 50-150 mesh, for example, it can be 50 mesh, 75 mesh, 90 mesh, 110 mesh, 120 mesh, 135 mesh or 150 mesh, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] As a preferred technical solution of the present invention, the calcination temperature in step (2) is 800-950℃, for example, it can be 800℃, 820℃, 850℃, 900℃, 930℃ or 950℃, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the calcination time in step (2) is 60-120 min, for example, it can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] Preferably, the hot air obtained after the calcination tail gas in step (2) exchanges heat with cold air is used as the heat source for the drying and dehydration, the low-temperature drying and the post-treatment of the salt solution.

[0030] This invention effectively utilizes the waste heat of calcination tail gas, reduces energy consumption, realizes the cascade utilization of energy, reduces system operating costs, and improves process economy.

[0031] Preferably, the temperature of the hot air is 250-350℃, for example, it can be 250℃, 280℃, 310℃, 330℃, 340℃ or 350℃, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] As a preferred technical solution of the present invention, the water immersion treatment in step (3) includes three-stage countercurrent immersion.

[0033] Preferably, the water immersion treatment in step (3) is carried out at a temperature of 20-70°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, or 70°C, and for a time of 30-60 minutes, such as 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, in the water immersion treatment process described in step (3), the mass ratio of the calcined product to water is 1:(1-2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0035] Preferably, the specific steps of the post-processing in step (4) include:

[0036] The precipitate is dehydrated, and the salt solution is evaporated and crystallized.

[0037] Preferably, the dehydration treatment temperature is 100-150℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃, and the time is 30-60 minutes, for example, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the evaporation and crystallization temperature is 130-150℃, for example, it can be 130℃, 135℃, 140℃, 145℃ or 150℃, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0039] As a preferred technical solution of the present invention, the resource utilization method includes the following steps:

[0040] (1) Dry and dehydrate industrial phosphogypsum at 150-300℃ to obtain phosphogypsum powder. Crush and sieve the reducing agent to obtain reducing agent powder with a mesh size of 50-150 mesh. Dry organic waste salt at 50-100℃ to obtain dried waste salt.

[0041] The obtained phosphogypsum powder, dried waste salt and reducing agent powder are mixed and granulated in a mass ratio of 100:(15-30):(10-25) to obtain a mixture with a particle size of 1-5 mm.

[0042] (2) The mixture is calcined at 800-950℃ for 60-120 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas.

[0043] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 250-350℃, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of salt solution.

[0044] (3) The calcined product is pulverized to a mesh size of 100-200 mesh, and then subjected to three-stage countercurrent leaching at a temperature of 20-70℃ for 30-60 min. The mass ratio of the calcined product to water is 1:(1-2). After leaching, liquid-solid separation is performed to obtain a precipitate and a solution containing sodium chloride.

[0045] The precipitate is dehydrated at 100-150℃ for 30-60 minutes to obtain calcium sulfide product. The sodium chloride-containing solution is evaporated and crystallized at 130-150℃ to obtain sodium chloride product.

[0046] In a second aspect, the present invention provides a resource utilization system for industrial phosphogypsum and organic waste salt, wherein the resource utilization system performs the resource utilization method described in the first aspect.

[0047] The resource utilization system includes a material mixing unit, a calcination and decomposition unit, a leaching and separation unit, and a post-processing unit connected sequentially along the material flow direction.

[0048] The resource utilization system provided by this invention can regenerate and utilize industrial phosphogypsum and industrial organic waste salts, and can dispose of solid waste on a large scale, achieving efficient and clean utilization.

[0049] As a preferred embodiment of the present invention, the material mixing unit includes a mixing and granulation device.

[0050] In this invention, the mixing and granulation device is used to mix and granulate phosphogypsum powder, reducing agent powder, and dried waste salt in a certain mass ratio to obtain a mixture.

[0051] Preferably, the mixing granulation device is a mixing granulator.

[0052] Preferably, the resource utilization system further includes a pretreatment unit, which includes a drying and dehydration device, a crushing device, and a low-temperature drying device. The outlets of the drying and dehydration device, the crushing device, and the low-temperature drying device are respectively connected to the mixing and granulation device.

[0053] In this invention, the drying and dehydration device is used to dry and dehydrate industrial phosphogypsum to obtain phosphogypsum powder.

[0054] Preferably, the drying and dehydration device is a rotary flash dryer.

[0055] It should be noted that the rotary flash dryer is a high-temperature gas drying device equipped with a screw feeder.

[0056] In this invention, the crushing device is used to pulverize and sieve the reducing agent to obtain reducing agent powder with a certain particle size.

[0057] Preferably, the crushing device is a crusher.

[0058] In this invention, a low-temperature drying device is used to dry organic waste salt at low temperatures, remove free water, and obtain dried waste salt particles.

[0059] Preferably, the low-temperature drying device is a vibrating bed dryer.

[0060] Preferably, the vibrating bed dryer is made of a corrosion-resistant material, such as stainless steel.

[0061] Preferably, the calcination and decomposition unit includes a high-temperature calcination device, the outlet of the mixing and granulation device is connected to the inlet of the high-temperature calcination device, and the high-temperature calcination device is provided with a solid outlet and a gas outlet.

[0062] In this invention, a high-temperature calcination device is used to reduce and calcine the mixture to obtain a calcination product containing calcium sulfide and sodium chloride and a calcination tail gas. The calcination product is output from the solid outlet, and the calcination tail gas is output from the gas outlet.

[0063] Preferably, the high-temperature calcination device is a high-temperature calcination kiln.

[0064] It should be noted that the kiln tail of the high-temperature calcining kiln is equipped with a material cooling and storage device.

[0065] Preferably, a grinding device is provided between the calcination decomposition unit and the leaching separation unit, and the inlet of the grinding device is connected to the solid outlet.

[0066] Preferably, the grinding device is a grinding machine.

[0067] Preferably, the leaching separation unit includes a leaching device and a filtration device connected sequentially along the material flow direction, the inlet of the leaching device is connected to the outlet of the grinding device, and the filtration device is provided with a solid phase outlet and a liquid phase outlet.

[0068] Preferably, the leaching device is a leaching tank.

[0069] Preferably, the leaching tank is made of a chloride ion resistant material, such as steel lined with PTFE.

[0070] Preferably, the leaching tank is a pulping device, and the upper end of the pulping device is equipped with a cold water inlet and a stirring device.

[0071] Preferably, the filtration device is a plate and frame filter press.

[0072] In this invention, a precipitate and a sodium chloride-containing solution can be obtained through a leaching device and a filtration device.

[0073] Preferably, a discharge pump is further provided between the leaching device and the filtration device, the inlet of the discharge pump being connected to the outlet of the leaching device, and the outlet of the discharge pump being connected to the inlet of the filtration device.

[0074] Preferably, the post-processing unit includes a dehydration device and an evaporation crystallization device;

[0075] A conveying device is provided between the dehydration device and the filtration device. The inlet of the conveying device is connected to the solid phase outlet of the filtration device, and the outlet of the conveying device is connected to the inlet of the dehydration device.

[0076] A liquid outlet pump is provided between the filtration device and the evaporation crystallization device. The inlet of the liquid outlet pump is connected to the liquid phase outlet of the filtration device, and the outlet of the liquid outlet pump is connected to the inlet of the evaporation crystallization device.

[0077] Preferably, the dehydration device is a drum dryer.

[0078] Preferably, the conveying device is a belt conveyor.

[0079] In this invention, the precipitate is dehydrated to obtain calcium sulfide product.

[0080] Preferably, the evaporation crystallization apparatus includes an evaporator crystallizer and a particle dryer connected in sequence.

[0081] In this invention, a sodium chloride solution is passed through an evaporator crystallizer and a particle dryer to obtain sodium chloride product.

[0082] As a preferred embodiment of the present invention, the resource utilization system further includes an exhaust gas purification unit, the inlet of which is connected to the gas outlet of the calcination and decomposition unit.

[0083] Preferably, the exhaust gas purification unit includes a heat exchange device and an exhaust gas absorption device connected sequentially along the gas flow direction.

[0084] Preferably, the exhaust gas absorption device is an exhaust gas absorption tower.

[0085] Preferably, the heat exchange device is a heat exchanger.

[0086] Preferably, the tube-side inlet of the heat exchanger is connected to the gas outlet of the high-temperature calcining device.

[0087] Preferably, the exhaust gas purification unit further includes a blower, the shell-side inlet of the heat exchanger is connected to the outlet of the blower, and the shell-side outlet of the heat exchanger is connected to the gas inlet of the drying and dehydration device, the gas inlet of the low-temperature drying device, and the gas inlet of the particle dryer, respectively.

[0088] Preferably, the blowing device is a blower.

[0089] Preferably, an induced draft device is provided between the heat exchange device and the exhaust gas absorption device, the inlet of the induced draft device is connected to the tube outlet of the heat exchange device, and the outlet of the induced draft device is connected to the gas inlet of the exhaust gas absorption device.

[0090] Preferably, the exhaust fan is an acid-resistant exhaust gas exhaust fan.

[0091] Thirdly, the present invention provides an application of the resource utilization method of industrial phosphogypsum and organic waste salt as described in the first aspect, wherein the resource utilization method is applied to the field of solid waste resource utilization technology.

[0092] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] (1) This invention utilizes the reducing properties of organic matter in waste salt at high temperatures to promote the decomposition of phosphogypsum. Furthermore, the presence of phosphogypsum avoids problems such as caking and scaling, achieving the goal of "treating waste with waste." Moreover, this invention utilizes the high-temperature melting characteristics of organic waste salt to lower the decomposition temperature of phosphogypsum to 800-950℃, a reduction of 150-200℃ compared to the conventional decomposition temperature of phosphogypsum. This reduces energy consumption, saves costs, and achieves a conversion rate of over 98% for the decomposition of phosphogypsum to calcium sulfide. Simultaneously, it removes organic matter from the organic waste salt, achieving a removal rate of over 99.5%, thus realizing the synergistic and efficient resource utilization of both solid wastes. Therefore, the method provided by this invention not only achieves the resource utilization of phosphogypsum and eliminates the environmental pollution risks posed by phosphogypsum, but also completely eliminates organic waste salt pollution, realizing the harmless and synergistic resource utilization of both solid wastes. It is a green and clean new process.

[0095] (2) The resource utilization system provided by the present invention can realize the recycling of industrial phosphogypsum and industrial organic waste salt, and can dispose of solid waste on a large scale, achieving efficient and clean utilization. Attached Figure Description

[0096] Figure 1 This is a schematic flowchart of a method for the resource utilization of industrial phosphogypsum and organic waste salt in a specific embodiment of the present invention.

[0097] Figure 2 This is a schematic diagram of a resource utilization system for industrial phosphogypsum and organic waste salt in a specific embodiment of the present invention.

[0098] Among them, 1-rotary flash dryer, 2-crusher, 3-vibrating bed dryer, 4-mixing granulator, 5-high temperature calcining kiln, 6-heat exchanger, 7-acid-resistant tail gas induced draft fan, 8-tail gas absorption tower, 9-blower, 10-grinding mill, 11-leaching tank, 12-discharge pump, 13-plate and frame filter press, 14-liquid discharge pump, 15-evaporator crystallizer, 16-granule dryer, 17-belt conveyor, 18-drum dryer. Detailed Implementation

[0099] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms 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," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0100] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" 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.

[0101] In one specific embodiment, the present invention provides a resource utilization system for industrial phosphogypsum and organic waste salt, the schematic diagram of which is shown below. Figure 2 As shown;

[0102] The resource utilization system includes a material mixing unit, a calcination and decomposition unit, a leaching and separation unit, and a post-processing unit connected sequentially along the material flow direction.

[0103] The resource utilization system provided by this invention can regenerate and utilize industrial phosphogypsum and industrial organic waste salts, and can dispose of solid waste on a large scale, achieving efficient and clean utilization.

[0104] Furthermore, the material mixing unit includes a mixing and granulation device.

[0105] In this invention, the mixing and granulation device is used to grind and mix phosphogypsum powder, reducing agent powder, and dried waste salt in a certain mass ratio to obtain a mixture.

[0106] Furthermore, the mixing granulation device is a mixing granulator 4.

[0107] Furthermore, the resource utilization system also includes a pretreatment unit, which includes a drying and dehydration device, a crushing device, and a low-temperature drying device. The outlets of the drying and dehydration device, the crushing device, and the low-temperature drying device are respectively connected to the mixing and granulation device.

[0108] In this invention, the drying and dehydration device is used to dry and dehydrate industrial phosphogypsum to obtain phosphogypsum powder.

[0109] Furthermore, the drying and dehydration device is a rotary flash dryer 1.

[0110] It should be noted that the rotary flash dryer 1 is a high-temperature gas drying device equipped with a screw feeder.

[0111] In this invention, the crushing device is used to pulverize and sieve the reducing agent to obtain reducing agent powder with a certain particle size.

[0112] Furthermore, the crushing device is a crusher 2.

[0113] In this invention, a low-temperature drying device is used to dry organic waste salt at low temperatures, remove free water, and obtain dried waste salt particles.

[0114] Furthermore, the low-temperature drying device is a vibrating bed dryer 3.

[0115] Furthermore, the vibrating bed dryer 3 is made of a corrosion-resistant material, such as stainless steel.

[0116] Furthermore, the calcination and decomposition unit includes a high-temperature calcination device, the outlet of the mixing and granulation device is connected to the inlet of the high-temperature calcination device, and the high-temperature calcination device is provided with a solid outlet and a gas outlet.

[0117] In this invention, a high-temperature calcination device is used to reduce and calcine the mixture to obtain a calcination product containing calcium sulfide and sodium chloride and a calcination tail gas. The calcination product is output from the solid outlet, and the calcination tail gas is output from the gas outlet.

[0118] Furthermore, the high-temperature calcination device is a high-temperature calcination kiln 5.

[0119] It should be noted that the kiln tail of the high-temperature calcining kiln 5 is equipped with a material cooling and storage device.

[0120] Furthermore, a grinding device is provided between the calcination decomposition unit and the leaching separation unit, and the inlet of the grinding device is connected to the solid outlet.

[0121] Furthermore, the grinding device is a grinding machine 10.

[0122] Furthermore, the leaching separation unit includes a leaching device and a filtration device connected sequentially along the material flow direction. The inlet of the leaching device is connected to the outlet of the grinding device, and the filtration device is provided with a solid phase outlet and a liquid phase outlet.

[0123] Furthermore, the leaching device is a leaching tank 11.

[0124] Furthermore, the leaching tank 11 is made of a chloride ion resistant material, such as steel lined with PTFE.

[0125] Furthermore, the leaching tank 11 is a pulping device, and the upper end of the pulping device is equipped with a cold water inlet and a stirring device.

[0126] Furthermore, the filtration device is a plate and frame filter press 13.

[0127] In this invention, a precipitate and a sodium chloride-containing solution can be obtained through a leaching device and a filtration device.

[0128] Furthermore, a discharge pump 12 is provided between the leaching device and the filtration device. The inlet of the discharge pump 12 is connected to the outlet of the leaching device, and the outlet of the discharge pump 12 is connected to the inlet of the filtration device.

[0129] Furthermore, the post-processing unit includes a dehydration device and an evaporation crystallization device;

[0130] A conveying device is provided between the dewatering device and the filtration device. The inlet of the conveying device is connected to the solid phase outlet of the filtration device, and the outlet of the conveying device is connected to the inlet of the dewatering device.

[0131] A liquid outlet pump 14 is provided between the filtration device and the evaporation crystallization device. The inlet of the liquid outlet pump 14 is connected to the liquid phase outlet of the filtration device, and the outlet of the liquid outlet pump 14 is connected to the inlet of the evaporation crystallization device.

[0132] Furthermore, the dehydration device is a drum dryer 18.

[0133] Furthermore, the conveying device is a belt conveyor 17.

[0134] In this invention, the precipitate is dehydrated to obtain calcium sulfide product.

[0135] Furthermore, the evaporation crystallization apparatus includes an evaporator crystallizer 15 and a particle dryer 16 connected in sequence.

[0136] In this invention, a sodium chloride solution is passed through an evaporator crystallizer 15 and a particle dryer 16 to obtain a sodium chloride product.

[0137] Furthermore, the resource utilization system also includes an exhaust gas purification unit, the inlet of which is connected to the gas outlet of the calcination and decomposition unit.

[0138] Furthermore, the exhaust gas purification unit includes a heat exchange device and an exhaust gas absorption device connected sequentially along the gas flow direction.

[0139] Furthermore, the exhaust gas absorption device is an exhaust gas absorption tower 8.

[0140] Furthermore, the heat exchange device is a heat exchanger 6.

[0141] Furthermore, the tube-side inlet of the heat exchanger 6 is connected to the gas outlet of the high-temperature calcining device.

[0142] Furthermore, the exhaust gas purification unit also includes a blower, the shell-side inlet of the heat exchanger 6 is connected to the outlet of the blower, and the shell-side outlet of the heat exchanger 6 is connected to the gas inlet of the drying and dehydration device, the gas inlet of the low-temperature drying device, and the gas inlet of the particle dryer 16, respectively.

[0143] Furthermore, the blowing device is a blower 9.

[0144] Furthermore, an induced draft device is provided between the heat exchange device and the exhaust gas absorption device. The inlet of the induced draft device is connected to the tube outlet of the heat exchange device, and the outlet of the induced draft device is connected to the gas inlet of the exhaust gas absorption device.

[0145] Furthermore, the exhaust fan is an acid-resistant exhaust gas fan 7.

[0146] In another specific embodiment, the present invention provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the process flow diagram of which is shown below. Figure 1 As shown, the resource utilization method includes the following steps:

[0147] (1) Dry and dehydrate industrial phosphogypsum at 150-300℃ to obtain phosphogypsum powder. Crush and sieve the reducing agent to obtain reducing agent powder with a mesh size of 50-150 mesh. Dry organic waste salt at 50-100℃ to obtain dried waste salt.

[0148] The obtained phosphogypsum powder, dried waste salt and reducing agent powder are mixed and granulated in a mass ratio of 100:(15-30):(10-25) to obtain a mixture with a particle size of 1-5 mm.

[0149] (2) The mixture is calcined at 800-950℃ for 60-120 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas.

[0150] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 250-350℃, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of salt solution.

[0151] (3) The calcined product is pulverized to a mesh size of 100-200 mesh, and then subjected to three-stage countercurrent leaching at a temperature of 20-70℃ for 30-60 min. The mass ratio of the calcined product to water is 1:(1-2). After leaching, liquid-solid separation is performed to obtain a precipitate and a solution containing sodium chloride.

[0152] The precipitate is dehydrated at 100-150℃ for 30-60 minutes to obtain calcium sulfide product. The sodium chloride-containing solution is evaporated and crystallized at 130-150℃ to obtain sodium chloride product.

[0153] Example 1

[0154] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0155] (1) Industrial phosphogypsum is dried and dehydrated at 200°C to obtain phosphogypsum powder. The reducing agent coke is crushed and sieved to obtain reducing agent powder with a mesh size of 130 mesh. Organic waste salt containing sodium chloride is dried at 80°C to obtain dried waste salt.

[0156] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:20:25 to obtain a mixture with a particle size of 5 mm.

[0157] (2) The mixture is calcined at 950°C for 100 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0158] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 320°C, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of sodium chloride solution.

[0159] (3) The calcined product is crushed to a mesh size of 180 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 40℃ and the time is 40min. The mass ratio of calcined product to water is 1:2. After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution.

[0160] The precipitate was dehydrated at 150°C for 50 minutes to obtain calcium sulfide product, and the sodium chloride-containing solution was evaporated and crystallized at 140°C to obtain sodium chloride product.

[0161] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide is 100%, and the removal rate of organic matter from organic waste salt is 100%.

[0162] Example 2

[0163] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0164] (1) Industrial phosphogypsum is dried and dehydrated at 150°C to obtain phosphogypsum powder. Coal powder is crushed and sieved to obtain reducing agent powder with a mesh size of 120. Organic waste salt containing sodium chloride is dried at 100°C to obtain dried waste salt.

[0165] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:25:15 to obtain a mixture with a particle size of 1 mm.

[0166] (2) The mixture is calcined at 800°C for 120 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0167] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 250°C, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of salt solution.

[0168] (3) The calcined product is crushed to a mesh size of 100 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 70℃ and the time is 30min. The mass ratio of calcined product to water is 1:1.3. After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution.

[0169] The precipitate was dehydrated at 130°C for 60 minutes to obtain calcium sulfide product. The sodium chloride-containing solution was evaporated and crystallized at 130°C to obtain sodium chloride product.

[0170] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide was 99.2%, and the organic matter removal rate from organic waste salt was 99.5%.

[0171] Example 3

[0172] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0173] (1) Industrial phosphogypsum is dried and dehydrated at 300°C to obtain phosphogypsum powder. The reducing agent biomass particles are crushed and sieved to obtain reducing agent powder with a mesh size of 70 mesh. Organic waste salt containing sodium chloride is dried at 50°C to obtain dried waste salt.

[0174] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:15:10 to obtain a mixture with a particle size of 3 mm.

[0175] (2) The mixture is calcined at 800°C for 80 minutes to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0176] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The hot air obtained after heat exchange has a temperature of 300°C and is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of sodium chloride solution.

[0177] (3) The calcined product is crushed to a mesh size of 200 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 60℃ and the time is 50min. The mass ratio of calcined product to water is 1:1.8. After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution.

[0178] The precipitate was dehydrated at 100°C for 40 minutes to obtain calcium sulfide product, and the sodium chloride-containing solution was evaporated and crystallized at 150°C to obtain sodium chloride product.

[0179] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide was 98.1%, and the organic matter removal rate from organic waste salt was 99.6%.

[0180] Example 4

[0181] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0182] (1) Industrial phosphogypsum is dried and dehydrated at 250°C to obtain phosphogypsum powder. Coal powder is crushed and sieved to obtain reducing agent powder with a mesh size of 150. Organic waste salt containing sodium chloride is dried at 90°C to obtain dried waste salt.

[0183] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:25:13 to obtain a mixture with a particle size of 4 mm.

[0184] (2) The mixture is calcined at 900°C for 90 minutes to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0185] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 310°C, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of sodium chloride solution.

[0186] (3) The calcined product is crushed to a mesh size of 130 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 20°C and the time is 60 min. The mass ratio of calcined product to water is 1:1. After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution.

[0187] The precipitate was dehydrated at 140°C for 30 minutes to obtain calcium sulfide product, and the sodium chloride-containing solution was evaporated and crystallized at 135°C to obtain sodium chloride product.

[0188] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide was 98.5%, and the organic matter removal rate from organic waste salt was 99.8%.

[0189] Example 5

[0190] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0191] (1) Industrial phosphogypsum is dried and dehydrated at 300°C to obtain phosphogypsum powder. The reducing agent biomass particles are crushed and sieved to obtain reducing agent powder with a mesh size of 50. Organic waste salt containing sodium chloride is dried at 70°C to obtain dried waste salt.

[0192] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:30:22 to obtain a mixture with a particle size of 2 mm.

[0193] (2) The mixture is calcined at 950°C for 60 minutes to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0194] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The hot air obtained after heat exchange has a temperature of 350°C and is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of sodium chloride solution.

[0195] (3) The calcined product is crushed to a mesh size of 150 mesh, and then subjected to three-stage countercurrent leaching at a temperature of 50°C for 50 min. The mass ratio of the calcined product to water is 1:1.5. After leaching, liquid-solid separation is performed to obtain a precipitate and a solution containing sodium chloride.

[0196] The precipitate was dehydrated at 120°C for 50 minutes to obtain calcium sulfide product. The sodium chloride-containing solution was evaporated and crystallized at 1145°C to obtain sodium chloride product.

[0197] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide was 99.9%, and the removal rate of organic matter from organic waste salt was 99.9%.

[0198] Example 6

[0199] This embodiment provides a method for the resource utilization of industrial phosphogypsum and organic waste salt, the method comprising the following steps:

[0200] (1) Industrial phosphogypsum is dried and dehydrated at 200°C to obtain phosphogypsum powder. The reducing agent coke powder is crushed and sieved to obtain reducing agent powder with a mesh size of 100 mesh. The organic waste salt containing sodium chloride is dried at 60°C to obtain dried waste salt.

[0201] The obtained phosphogypsum powder, dried waste salt and reducing agent powder were mixed and granulated in a mass ratio of 100:18:20 to obtain a mixture with a particle size of 3 mm.

[0202] (2) The mixture is calcined at 900°C for 100 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas containing high residual heat.

[0203] The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The hot air obtained after heat exchange has a temperature of 280°C and is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of sodium chloride solution.

[0204] (3) The calcined product is crushed to a mesh size of 140 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 50°C and the time is 45 min. The mass ratio of calcined product to water is 1:1.6. After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution.

[0205] The precipitate was dehydrated at 130°C for 40 minutes to obtain calcium sulfide product, and the sodium chloride-containing solution was evaporated and crystallized at 150°C to obtain sodium chloride product.

[0206] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide was 99.5%, and the organic matter removal rate from organic waste salt was 99.8%.

[0207] Example 7

[0208] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (2) is 500°C.

[0209] The remaining preparation methods and parameters are consistent with those in Example 1.

[0210] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide reached 0%, and the organic matter removal rate in organic waste salt was 46.6%.

[0211] Example 8

[0212] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (2) is 1000℃.

[0213] The remaining preparation methods and parameters are consistent with those in Example 1.

[0214] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide reached 91.2%, and the removal rate of organic matter from organic waste salt was 100%. Excessive calcination temperature causes the calcium sulfide product to transform into calcium oxide, thereby reducing the yield of calcium sulfide.

[0215] Example 9

[0216] The difference between this embodiment and embodiment 1 is that the calcination time in step (2) is 30 minutes.

[0217] The remaining preparation methods and parameters are consistent with those in Example 1.

[0218] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide reached 58%, and the organic matter removal rate from organic waste salt was 90.1%.

[0219] Example 10

[0220] The difference between this embodiment and embodiment 1 is that the calcination time in step (2) is 150 min.

[0221] The remaining preparation methods and parameters are consistent with those in Example 1.

[0222] In this embodiment, the conversion rate of phosphogypsum to calcium sulfide reached 100%, and the removal rate of organic matter from organic waste salt was 100%. Although both the conversion rate and the removal rate were 100%, the calcination time was too long, which greatly increased energy consumption and cost.

[0223] Comparative Example 1

[0224] The difference between this comparative example and Example 1 is that no reducing agent is added in step (1).

[0225] The remaining preparation methods and parameters are consistent with those in Example 1.

[0226] As can be seen from the above embodiments and comparative examples, the resource utilization method of industrial phosphogypsum and organic waste salt provided by the present invention utilizes the high-temperature melting characteristics of sodium chloride to reduce the decomposition temperature of phosphogypsum, while simultaneously removing organic matter from organic waste salt. Energy is utilized in stages, reducing energy consumption and costs, and realizing the synergistic and efficient resource utilization of "two solid wastes". It is a green and clean new process.

[0227] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0228] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0229] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0230] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for the resource utilization of industrial phosphogypsum and organic waste salt, characterized in that, The resource utilization method includes the following steps: (1) Industrial phosphogypsum, organic waste salt and reducing agent are mixed and granulated to obtain a mixture; the organic waste salt includes sodium chloride; In the mixture, the mass ratio of industrial phosphogypsum, organic waste salt and reducing agent is 100:(15-30):(10-25); (2) The mixture is calcined at a temperature of 800-950°C to obtain calcined products and calcined tail gas; (3) The calcined product is subjected to water immersion treatment to obtain a precipitate and a salt solution. The precipitate and the salt solution are then post-treated to obtain the recovered product.

2. The resource utilization method according to claim 1, characterized in that, The reducing agent includes any one or a combination of at least two of pulverized coal, coke powder, or biomass pellets.

3. The resource utilization method according to claim 1, characterized in that, The particle size of the mixture in step (1) is 1-5 mm.

4. The resource utilization method according to claim 1, characterized in that, Before mixing and granulating the industrial phosphogypsum, organic waste salt and reducing agent in step (1), the industrial phosphogypsum, organic waste salt and reducing agent are pretreated respectively.

5. The resource utilization method according to claim 4, characterized in that, The pretreatment method for industrial phosphogypsum includes drying and dehydration.

6. The resource utilization method according to claim 5, characterized in that, The drying and dehydration temperature is 150-300℃.

7. The resource utilization method according to claim 4, characterized in that, The pretreatment method for organic waste salt includes low-temperature drying.

8. The resource utilization method according to claim 7, characterized in that, The temperature for the low-temperature drying is 50-100℃.

9. The resource utilization method according to claim 4, characterized in that, The pretreatment of the reducing agent includes crushing and sieving.

10. The resource utilization method according to claim 9, characterized in that, The reducing agent, after being pulverized and sieved, has a mesh size of 50-150.

11. The resource utilization method according to claim 1, characterized in that, The calcination time in step (2) is 60-120 min.

12. The resource utilization method according to claim 1, characterized in that, In step (2), the calcination exhaust gas is heat-exchanged with cold air, and the resulting hot air is used as a heat source for drying and dehydration, low-temperature drying, and post-treatment of the salt-containing solution.

13. The resource utilization method according to claim 12, characterized in that, The temperature of the hot air is 250-350℃.

14. The resource utilization method according to claim 1, characterized in that, The water immersion treatment method described in step (3) includes three-stage countercurrent immersion.

15. The resource utilization method according to claim 1, characterized in that, The water immersion treatment in step (3) is carried out at a temperature of 20-70℃ for 30-60 minutes.

16. The resource utilization method according to claim 1, characterized in that, In the water immersion process described in step (3), the mass ratio of calcined product to water is 1:(1-2).

17. The resource utilization method according to claim 1, characterized in that, The specific steps of the post-processing described in step (3) include: The precipitate is dehydrated, and the salt solution is evaporated and crystallized.

18. The resource utilization method according to claim 17, characterized in that, The dehydration process is carried out at a temperature of 100-150℃ for 30-60 minutes.

19. The resource utilization method according to claim 18, characterized in that, The evaporation and crystallization temperature is 130-150℃.

20. The resource utilization method according to claim 1, characterized in that, The resource utilization method includes the following steps: (1) Dry and dehydrate industrial phosphogypsum at 150-300℃ to obtain phosphogypsum powder, crush and sieve the reducing agent to obtain reducing agent powder with a mesh size of 50-150 mesh, and dry organic waste salt at 50-100℃ to obtain dried waste salt. The obtained phosphogypsum powder, dried waste salt and reducing agent powder are mixed and granulated in a mass ratio of 100:(15-30):(10-25) to obtain a mixture with a particle size of 1-5 mm. (2) The mixture is calcined at 800-950℃ for 60-120 min to obtain calcined products containing calcium sulfide and sodium chloride and calcined tail gas; The calcination tail gas is heat-exchanged with cold air. After heat exchange, the calcination tail gas is absorbed by alkali and then discharged into the air. The temperature of the hot air obtained after heat exchange is 250-350℃, which is used as a heat source for drying and dehydration, low-temperature drying and subsequent evaporation and crystallization of salt solution. (3) The calcined product is crushed to a mesh size of 100-200 mesh, and then three-stage countercurrent leaching is performed. The leaching temperature is 20-70℃ and the time is 30-60min. The mass ratio of the calcined product to water is 1:(1-2). After the leaching is completed, liquid-solid separation is performed to obtain precipitate and sodium chloride solution. The precipitate is dehydrated at 100-150℃ for 30-60 minutes to obtain calcium sulfide product. The sodium chloride-containing solution is evaporated and crystallized at 130-150℃ to obtain sodium chloride product.

21. An application of a method for the resource utilization of industrial phosphogypsum and organic waste salt as described in any one of claims 1-20, characterized in that, The resource utilization method described herein is applied to the field of solid waste resource utilization technology.

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