Phosphogypsum impurity removal method and device for directly mixing and harmlessly treating barium slag and flash kiln

Abstract

The invention relates to the technical field of barium slag innocent treatment, in particular to a method and a device for removing impurities of phosphogypsum for directly mixing and innocent treatment of barium slag and a flash kiln, the moisture content is reduced by drying at a lower temperature, then flash burning treatment is performed at a higher temperature, free water on the surface of the phosphogypsum is partially removed, and then flash burning is performed; the content of harmful components in the ardealite is reduced, the performance of the ardealite is guaranteed to be suitable for treating the barium slag, the capacity of the ardealite for harmlessly treating the barium slag is improved, the leaching toxicity of the barium slag for harmlessly treating the barium slag is reduced, and the stability of the ardealite after harmlessly treating the barium slag is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of harmless treatment of barium slag, and in particular to a method and device for removing impurities from phosphogypsum used for direct mixing and harmless treatment of barium slag, and a flash kiln. Background Art

[0002] Barium slag is made of barite as raw material. Barium sulfate is reduced by carbon at high temperature and then leached with water to produce the residual solid waste. It mainly contains unreacted barium sulfate, acid-soluble barium carbonate and water-soluble barium sulfide. The leached barium ion content and pH value are alkaline, far exceeding the standard limits of "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB / T5085.3-2007), and is a hazardous solid waste.

[0003] Barium slag digestion mainly relies on stockpiling, resource utilization and harmless disposal. Among the three barium slag digestion methods, harmless disposal consumes a larger amount of barium slag, and can make resource utilization after harmless disposal, increase the consumption of barium slag, and reduce the secondary pollution caused by the resource utilization of barium slag. Phosphogypsum is a solid waste discharged from the wet phosphoric acid process. Its main component is calcium sulfate dihydrate, which contains a large amount of phosphoric acid and its salts. It is acidic and can neutralize the alkalinity of barium slag to reduce the alkaline corrosiveness of barium slag. Therefore, the technology of harmlessly treating barium slag using phosphogypsum has been developed and studied, and relevant technical literature has been obtained.

[0004] For example: Patent No. 201710889338.0 discloses a method for harmlessly treating barium slag using phosphogypsum, wherein the barium slag is ground to a mesh size of 50 and water is injected to a moisture content of 15-17%; the phosphogypsum is ground to a mesh size of 50 and water is injected to a moisture content of 3-4.2%, and then the barium slag and the phosphogypsum after water injection are stirred and mixed at a mass ratio of 10:1-20, subjected to ultrasonic vibration, and dehydrated to obtain a mixed slag, thereby achieving the fixation of barium salts in the barium slag and reducing the dissolution solubility of soluble phosphorus in the phosphogypsum, achieving the effect of treating waste with waste, and reducing the leaching toxicity of the barium slag and the corrosiveness of the mixed slag.

[0005] Another example: the barium slag and phosphogypsum synergistic harmless treatment method with patent application number 202111296494.9 is completed by mixing barium slag and phosphogypsum in a specific mass ratio, stirring at 500r / min for a specific time, and aging for a specific time, so that the barium ion leaching toxicity is less than 25mg / L, and the pH is between 6-8, thereby reducing the acid and alkali corrosiveness of the harmless treatment slag.

[0006] Another example: the method and application of harmless treatment of barium slag with patent application number 202311217879.0, the barium slag and phosphogypsum are crushed, sprayed with water, the moisture content is controlled to be about 34%, mixed in a mass ratio of 7:3, and stabilizer 2, stabilizer 1, and stabilizer 3 are added in sequence and stirred to achieve waste treatment with waste, adjust the pH of the mixed slag, realize true harmless treatment of barium slag, and reduce acid and alkali corrosiveness.

[0007] However, phosphogypsum also contains fluoride, phosphorus pentoxide and other components, and the relative content of these components varies with the origin of the phosphate rock, making it contain more types of chemical components, making it difficult to utilize the barium slag for harmless treatment of phosphogypsum resources. Therefore, when using phosphogypsum as a raw material for harmless treatment of barium slag, it is necessary to remove impurities and purify the phosphogypsum to improve the harmless treatment effect and reduce leaching toxicity and acid-base corrosiveness, which has become a technical direction of concern to those skilled in the art.

[0008] At present, the methods for removing impurities from phosphogypsum mainly include physical methods and chemical methods. The physical method is a method of separating soluble impurities and a small amount of insoluble impurities in phosphogypsum by physical operations such as water washing, flotation, and screening. Its cost is relatively low, but it is difficult to effectively remove water-insoluble impurities and impurities existing inside the phosphogypsum crystals, which makes it difficult to effectively remove water-insoluble impurities and impurities existing inside the phosphogypsum crystals, resulting in poor harmless stability of the mixed slag after mixing with barium slag for harmless treatment. The chemical method is to use chemicals to put phosphogypsum into it to convert impurities into inert substances or soluble substances, such as: using alkali treatment with lime neutralization or acid treatment with acid leaching to reduce the fluorine removal effect of phosphogypsum and reduce the impurity content, but this method has a high processing cost and will introduce other chemical components, resulting in the treated phosphogypsum being unsuitable for barium slag harmless treatment, and the barium slag harmless treatment effect is poor. Summary of the invention

[0009] Based on the above technical problems, the present invention provides a method and device for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag and a flash kiln.

[0010] The specific technical solution is:

[0011] One of the purposes of the invention is to provide a method for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag, comprising the following steps:

[0012] S1: drying the phosphogypsum in a drying tower until the moisture content is ≤10%, and then sending it to a flash kiln for flash burning to obtain volatile tail gas, flash gypsum and hot air;

[0013] S2: The tail gas is sent to a spray tower, sprayed with lime water for treatment, and precipitated to obtain precipitate residue and supernatant; the supernatant is returned and mixed with lime water and then sprayed on the tail gas for treatment;

[0014] S3: The hot gas is returned to the drying tower for heat exchange to pre-dry the phosphogypsum, and then circulated with the precipitated slag to exchange heat to room temperature to obtain dry slag and cooling gas, which is then discharged;

[0015] Or the hot air is divided into two parts, one part is returned to the drying tower for heat exchange to pre-dry the phosphogypsum, and then circulated with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is discharged; the other part is directly circulated with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is discharged;

[0016] Or the hot air is directly circulated with the precipitated slag to exchange heat to room temperature, and dry slag and cooling gas are obtained, and the cooling gas is discharged;

[0017] S4: The flash gypsum is crushed and packaged.

[0018] By drying at a relatively low temperature to reduce the moisture content, and then flash burning at a relatively high temperature, free water on the surface of the phosphogypsum is partially removed and then flash burned. Inorganic phosphorus combines with calcium at high temperature to form inert calcium pyrophosphate, which causes volatile components such as phosphorus, sulfur, and fluorine in the phosphogypsum to volatilize and escape the treatment, thereby reducing the content of harmful components in the phosphogypsum, ensuring that the performance of the phosphogypsum is suitable for treating barium slag, improving the ability of the phosphogypsum to harmlessly treat barium slag, reducing the leaching toxicity of the barium slag harmlessly treated, and enhancing the stability of the phosphogypsum after harmless treatment of barium slag.

[0019] In order to avoid excessive flash burning during the impurity removal process of phosphogypsum, which may result in the barium slag being unsuitable for harmless treatment, preferably, in step S1, the flash burning temperature is 400-600°C and the flash burning time is 5-15 minutes.

[0020] In order to improve the absorption effect of volatile components in tail gas, preferably, the pH value of the lime water is ≥10, and the mass concentration is 10-15% in terms of calcium hydroxide.

[0021] The second purpose of the invention is to provide a phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag, comprising a drying tower and a flash kiln, wherein the flash kiln is provided with a feed port, a discharge port, a volatile discharge port and a hot air pipe; the drying tower is provided with a feed port, a discharge port, a circulation inlet and a circulation outlet; the discharge port is connected to the feed port, and the hot air pipe is connected to the circulation inlet; the volatile discharge port is connected to a spray tower, and the spray tower is connected to a sedimentation tank; the sedimentation tank is connected to a clear liquid tank and a heat exchange tower, the clear liquid tank is connected to a circulation pool, the circulation pool is connected to a lime water tank, and the circulation pool is connected to the spray tower; the circulation outlet is connected to the heat exchange tower and can exchange heat, and the heat exchange tower is connected to a dry slag tank; the discharge port is connected to a pulverizer.

[0022] In order to ensure that the temperature of the hot air and the precipitated slag in contact and heat exchange can meet the requirements of drying the precipitated slag, preferably, the hot air pipe is connected to the heat exchange tower and can exchange heat, and the hot air pipe is connected to the circulation inlet. More preferably, the hot air pipe is directly connected to the heat exchange tower and can exchange heat.

[0023] Through the connection between the drying tower and the flash kiln, the hot air generated by the flash kiln and the tail gas volatilized by the flash kiln can be treated and utilized separately, so as to realize the recycling of heat in the hot air, improve the heat utilization rate, reduce the cost of impurity removal treatment of phosphogypsum, and realize the pre-drying of phosphogypsum to reduce the surface free water content, so as to ensure that the flash gypsum obtained by the flash kiln is suitable for the harmless treatment of barium slag, and improve the effect of the harmless treatment of barium slag by phosphogypsum; at the same time, the tail gas is treated by connecting the spray tower, the sedimentation tank and the heat exchange tower, so that the volatile components, such as fluorine and other components, are generated into calcium fluoride for recycling, and the precipitation supernatant can be circulated and sprayed in the circulation pool after adjusting the pH and concentration, so as to reduce the amount of waste liquid discharged and help to improve the recovery rate of elements such as fluorine.

[0024] In order to realize automated and intelligent processing, preferably, the crusher is connected to a storage bin; and / or the feed port is connected to a phosphogypsum tank.

[0025] In order to timely control and monitor the pH value and concentration of limewater in the circulation pool, preferably, the circulation pool is connected with a pH detection sensor and a concentration detector. The pH detection sensor is a commonly used pH detection sensor well known to those skilled in the art. The concentration detection sensor is a calcium hydroxide concentration detector, such as BM2007Q calcium hydroxide measuring instrument, etc.

[0026] In order to ensure the collection efficiency and effect of volatile components and improve the processing efficiency, preferably, the flash kiln includes a bracket and a flash body installed on the bracket, the flash body includes a combustion chamber and a rotating chamber, the rotating chamber runs from the left end of the combustion chamber to the right end of the combustion chamber, and the rotating chamber can rotate freely in the combustion chamber; the combustion chamber is provided with a fuel port, a hot air pipe and a blower; a left cover is provided at the left end of the rotating chamber, and the left cover is provided with a feed port for feeding phosphogypsum into the rotating chamber; a right cover is provided at the right end of the rotating chamber, and the right cover is provided with a volatile discharge port and a discharge port; the left cover and the right cover are both fixed on the bracket, and the rotating chamber can rotate freely relative to the left cover and the right cover.

[0027] In order to remove the combustion slag produced by combustion in the combustion chamber, preferably, a slag discharge port is provided on the combustion chamber.

[0028] The present invention creates a toothed belt on the rotating cavity, and the toothed belt can be connected to a motor and drive the rotating cavity to rotate.

[0029] The third purpose of the invention is to provide a flash kiln for flash burning of phosphogypsum for direct mixing and harmless treatment of barium slag and impurities removal, comprising a bracket and a flash burning body installed on the bracket, the flash burning body comprising a combustion chamber and a rotating chamber, the rotating chamber runs from the left end of the combustion chamber to the right end of the combustion chamber, and the rotating chamber can rotate freely in the combustion chamber; the combustion chamber is provided with a fuel port, a hot air pipe and a blower; the left end of the rotating chamber is provided with a left cover, and the left cover is provided with a feed port for feeding phosphogypsum into the rotating chamber; the right end of the rotating chamber is provided with a right cover, and the right cover is provided with a volatile discharge port and a discharge port; the left cover and the right cover are both fixed on the bracket, and the rotating chamber can rotate freely relative to the left cover and the right cover. A left cover and a right cover are respectively arranged at the left and right ends of the rotating chamber, and a feed port is arranged on the left cover, and a volatile discharge port and a discharge port are arranged on the right cover. At the same time, the rotating chamber can rotate freely relative to the left cover and the right cover, thereby ensuring continuous processing and collection of volatile components, which helps to improve processing efficiency and reduce processing costs.

[0030] Compared with the prior art, the technical effects created by the present invention are embodied in:

[0031] The invention creates a method of treating phosphogypsum by using a pre-baking-flash burning-crushing process, and recovers and processes tail gases such as fluorine volatilized in the flash burning process to prepare dry slag (calcium fluoride), thereby reducing the content of toxic and harmful components such as fluorine in the phosphogypsum. At the same time, flash burning is used to ensure that the performance of the phosphogypsum product after impurities removal can meet the requirements of harmless treatment of barium slag, improve the effect of harmless treatment of barium slag, enhance the stability of the stacking of harmless treatment slag, improve the effect of resource utilization of harmless treatment slag, and reduce the risk of secondary pollution to the environment caused by resource utilization.

[0032] The invention detects the toxicity of barium ion leaching after 180 days of storage, and no obvious change is found. Compared with the traditional grinding-screening-water injection treatment process for treating phosphogypsum and then mixing it with barium slag, the harmless treatment effect of the barium slag can be enhanced to a greater extent, and the harmful components carried into the treatment agent can be reduced; and the treatment cost is low, and the fluorine resources in the tail gas can be recovered and utilized, which is helpful to reduce the cost of directly mixing with phosphogypsum to harmlessly treat the barium slag. At the same time, the patented equipment can also be used to directly treat the phosphogypsum into dehydrated gypsum for subsequent resource utilization of the phosphogypsum.

[0033] The invention utilizes lime water to treat tail gas, and recycles it after precipitation, thereby reducing water resource waste and tail gas treatment costs, and can produce calcium fluoride or calcium carbonate, effectively improving the recovery and utilization of valuable elements such as fluorine in phosphogypsum, improving the added value of the process of directly mixing phosphogypsum with barium slag for harmless treatment, and reducing the influence of fluorine and other elements on the storage stability of harmless slag due to the introduction of fluorine into the barium slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to facilitate those skilled in the art to fully understand the technical solution of the present invention, the present invention is now combined with the content of the technical solution and the provided drawings, and the following description is made for the provided drawings. The directional words described in the present invention, such as: up, down, front, back, left, right, etc., are all combined and made in conjunction with the following drawings for easy understanding, and are not a limitation of the technical solution of the present invention.

[0035] Figure 1 Create a process flow chart for the present invention.

[0036] Figure 2 for Figure 1 Another embodiment process flow chart.

[0037] Figure 3 for Figure 1 Another embodiment process flow chart.

[0038] Figure 4 The present invention creates a schematic diagram of the device connection structure.

[0039] Figure 5 for Figure 4 Another schematic diagram of the structure of the embodiment.

[0040] Figure 6 for Figure 4 Another schematic diagram of the structure of the embodiment.

[0041] Figure 7 This is a schematic diagram of the flash kiln structure.

[0042] Figure 8 This is a sample laboratory test report obtained by creating an embodiment of the present invention.

[0043] 1-phosphogypsum tank 2-drying tower 3-flash kiln 4-crusher 5-storage bin 6-spray tower 7-precipitation tank 8-heat exchange tower 9-dry slag tank 10-clear liquid tank 11-circulation pool 12-lime water tank.

[0044] 3.1- Combustion chamber 3.2- Rotation chamber 3.3- Hot air pipe 3.4- Fuel port 3.5- Blower 3.6- Bracket 3.7- Right cover 3.8- Left cover 3.9- Feed inlet 3.10- Discharge port 3.11- Volatile discharge port. DETAILED DESCRIPTION

[0045] In order to facilitate those skilled in the art to correctly understand the present invention and enable those skilled in the art to fully understand the technical content of the present invention, the technical solution of the present invention is further explained below in conjunction with specific implementation methods and drawings. However, this explanation does not limit the scope of protection required for the present invention. The scope of protection of the present invention by those skilled in the art cannot be limited to the following explanations. Any equivalent substitutions or changes made by any those skilled in the art or persons familiar with the technology in the art based on the present invention and the technical solution and inventive concept thereof should be covered within the scope of protection of the present invention.

[0046] like Figure 4 and Figure 7 As shown, in some embodiments, a phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag includes a drying tower 2 and a flash kiln 3, wherein the flash kiln 3 is provided with a feed port 3.9, a discharge port 3.10, a volatile discharge port 3.11 and a hot air pipe 3.3; the drying tower 2 is provided with a feed port, a discharge port, a circulation inlet and a circulation outlet; the discharge port is connected to the feed port 3.9, and the hot air pipe 3.3 is connected to the circulation inlet; the volatile discharge port 3.11 is connected to a spray tower 6, and the spray tower 6 is connected to a precipitation tank 7; the precipitation tank 7 is connected to a clear liquid tank 10 and a heat exchange tower 8, the clear liquid tank 10 is connected to a circulation pool 11, the circulation pool 11 is connected to a lime water tank 12, and the circulation pool 11 is connected to the spray tower 6; the circulation outlet is connected to the heat exchange tower 8 and can exchange heat, and the heat exchange tower 8 is connected to a dry slag tank 9; the discharge port 3.10 is connected to a pulverizer 4.

[0047] When in use, the flash kiln 3 is turned on to start combustion in the flash kiln 3 and discharge hot gas (combustion flue gas) from the hot gas pipe 3.3. On the basis of connecting the circulation inlet with the hot gas pipe 3.3, the discharged hot gas enters the drying tower 2, and then the phosphogypsum is added to the drying tower 2 through the feeding port, and heat is exchanged with the hot gas entering the circulation inlet to achieve the purpose of drying, so that the moisture content of the phosphogypsum is reduced to ≤10%, and enters the flash kiln 3 from the discharge port and the feed port 3.9 for flash combustion (the flash combustion temperature is between 400-600°C, and the flash combustion time is between 15-60min). The flashed phosphogypsum is discharged from the discharge port 3.10 and crushed by the pulverizer 4. After crushing, it can be directly mixed with barium slag to obtain harmless slag; the tail gas generated in the flash burning process is discharged through the volatile discharge port 3.11 and enters the spray tower 6, and is sprayed with lime water in the circulation pool 11 to form a precipitation slurry, and the precipitation slurry is precipitated in the precipitation tank 7 to form a supernatant and precipitation slag, and the precipitation slag is sent to the heat exchange tower 8 to exchange heat with the hot gas (combustion flue gas) discharged from the drying tower 2 and dry to obtain dry slag (calcium fluoride); the hot gas after heat exchange is cooled, and the cooling gas is absorbed by lime water to obtain calcium carbonate; the cooling gas can also be directly discharged; the supernatant obtained by precipitation is sent to the clear liquid tank 10, and circulated through the circulation pool 11 for spraying the tail gas in the spray tower 6. It can be seen that the device can realize the flash burning of phosphogypsum and realize the separate treatment of the combustion hot gas (combustion flue gas) generated in the flash burning process and the volatilized components in the phosphogypsum, realize the recovery and utilization of the valuable fluorine element in the phosphogypsum, reduce the cost of harmless treatment of barium slag after the flash burning of phosphogypsum, and at the same time, ensure the excellent performance of the phosphogypsum after flash burning. After applying it to the harmless treatment of barium slag, it can enhance the stability of the harmless slag, so that no increase in the toxicity of barium ion leaching is found after long-term (180d) stacking.

[0048] like Figure 5 As shown, in some embodiments, the hot air pipe 3.3 is connected to the heat exchange tower 8 and can exchange heat, and the hot air pipe 3.3 is connected to the circulation inlet, so that part of the hot air discharged from the flash combustion of phosphogypsum can be supplied to the phosphogypsum for preheating and then enter the heat exchange tower 8 for heat exchange and drying of the precipitated slag; the other part directly enters the heat exchange tower 8 for heat exchange and drying of the precipitated slag, thereby ensuring the hot air temperature requirement for drying the precipitated slag and improving energy utilization.

[0049] like Figure 6 As shown, in some embodiments, the hot air pipe 3.3 is directly connected to the heat exchange tower 8 and can exchange heat. The hot air discharged from the flash combustion of phosphogypsum directly enters the heat exchange tower 8 to dry the precipitated slag.

[0050] like Figure 4 and Figure 7As shown, in some embodiments, the pulverizer 4 is connected to the storage bin 5; and / or the feeding port is connected to the phosphogypsum tank 1. It can realize continuous storage after the pulverization is completed; it can also meet the continuity of feeding, meet the continuous drying-flash burning-pulverization, improve the efficiency of the phosphogypsum impurity removal process, and reduce the processing cost.

[0051] In some embodiments, the circulation pool 11 is connected to a pH detection sensor and a concentration detector. The pH detection sensor is a commonly used pH detection sensor well known to those skilled in the art. The concentration detection sensor is a calcium hydroxide concentration detector, such as BM2007Q calcium hydroxide measuring instrument. It can ensure the effect of treating the tail gas (volatile components) discharged during the flash combustion process at any time and improve the recovery rate of valuable elements such as fluorine. In the invention, the pH of the lime water in the circulation pool 11 is controlled to be ≥10, and the mass concentration of calcium hydroxide is 10-15%.

[0052] like Figure 7 As shown, in some embodiments, the flash kiln 3 includes a bracket 3.6 and a flash body mounted on the bracket 3.6, the flash body includes a combustion chamber 3.1 and a rotating chamber 3.2, the rotating chamber 3.2 runs from the left end of the combustion chamber 3.1 to the right end of the combustion chamber 3.1, and the rotating chamber 3.2 can rotate freely in the combustion chamber 3.1; the combustion chamber 3.1 is provided with a fuel port 3.4, a hot air pipe 3.3 and a blower 3.5; A left cover 3.8 is provided at the left end of the rotating chamber 3.2, and a feed port 3.9 capable of feeding phosphogypsum into the rotating chamber 3.2 is provided on the left cover 3.8; a right cover 3.7 is provided at the right end of the rotating chamber 3.2, and a volatile discharge port 3.11 and a discharge port 3.10 are provided on the right cover 3.7; the left cover 3.8 and the right cover 3.7 are both fixed on the bracket 3.6, and the rotating chamber 3.2 can rotate freely relative to the left cover 3.8 and the right cover 3.7.

[0053] The flash kiln 3 utilizes a combination of a rotating chamber 3.2 and a combustion chamber 3.1, so that the phosphogypsum is turned over in the rotating chamber 3.2 due to the rotation of the rotating chamber 3.2, and the combustion chamber 3.1 burns outside the rotating chamber 3.2 to provide heat, so that the phosphogypsum is heated evenly, and the volatile components in the phosphogypsum can escape quickly. At the same time, the flash temperature is between 400-600°C and the flash time is 15-60min to avoid excessive flashing of the phosphogypsum, ensure the performance of the phosphogypsum, and improve the harmless treatment effect of the barium slag by directly mixing the phosphogypsum after flashing, thereby enhancing the stability of the harmless slag and reducing the risk of secondary pollution to the environment caused by the resource utilization of the harmless slag. Moreover, the left cover 3.8 and the right cover 3.7 design structure make the volatile component recovery and the phosphogypsum feeding into the flash combustion process continuous, thereby improving the processing efficiency; at the same time, by utilizing the arrangement of the combustion chamber 3.1 and the rotating chamber 3.2 structure, the hot gas (combustion flue gas) generated by the combustion and the volatile components volatilized by the flash combustion are discharged and processed separately, so that the valuable elements such as fluorine are recycled and utilized to generate calcium fluoride, thereby increasing the added value; and the hot gas (combustion flue gas) generated by the combustion can be emptied after multiple cycles of heat utilization or absorbed by lime water to generate calcium carbonate, thereby improving the heat utilization rate and reducing the processing cost.

[0054] In some embodiments, the combustion chamber 3.1 is provided with a slag discharge port to facilitate the removal of slag formed by combustion in the combustion chamber 3.1.

[0055] In some embodiments, a toothed belt is provided on the rotating chamber 3.2, and the toothed belt can be connected to a motor and drive the rotating chamber 3.2 to rotate.

[0056] like Figure 1 As shown, in some embodiments, using Figure 4 and / or Figure 7 The impurity removal device or the flash kiln for phosphogypsum impurity removal is used for direct mixing and harmless treatment of barium slag and the method for removing impurities from phosphogypsum comprises the following steps:

[0057] S1: drying the phosphogypsum in a drying tower 2 to a moisture content of ≤10%, and then feeding it into a flash kiln 3 for flash treatment at a temperature of 400-600°C for 5-15 minutes to obtain volatile tail gas, flash gypsum and hot air;

[0058] S2: sending the tail gas to a spray tower 6, spraying it with lime water (pH value ≥ 10, and the mass concentration of calcium hydroxide is 10-15%), precipitating it, and obtaining precipitate residue and supernatant; the supernatant is returned and mixed with lime water and then sprayed on the tail gas for treatment;

[0059] S3: Figure 1 As shown, in some embodiments, the hot gas is returned to the drying tower 2 for heat exchange to pre-dry the phosphogypsum, and then circulated with the precipitated slag to obtain dry slag and cooling gas, which is then exhausted. Figure 2 As shown, in some embodiments, the hot gas is divided into two parts, one part returns to the drying tower 2 for heat exchange to pre-dry the phosphogypsum, and then circulates heat exchange with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is emptied; the other part directly circulates heat exchange with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is emptied. Figure 3 As shown, in some embodiments, the hot gas is directly circulated with the precipitated slag for heat exchange to room temperature to obtain dry slag and cooled gas, and the cooled gas is discharged.

[0060] S4: The flash gypsum is crushed and packaged.

[0061] The flash-burned gypsum obtained by the method is directly mixed with barium slag in a mass ratio of 1:10 and subjected to harmless treatment to prepare harmless slag. The stability of the harmless slag is enhanced, and there is no change in the toxicity of barium ion leaching after being piled for 180 days in a natural environment.

[0062] In order to better verify the technical effect that can be brought about by the technical solution of the present invention, the researchers of the present invention carried out the following experimental research, and the research was carried out on the basis of patent publication number CN 113996639 A (Example 1), and the specific contents that are not elaborated in detail are the same as those disclosed in patent publication number CN 113996639 A (Example 1).

[0063] Test 1: Detection of elements and composition of raw barium slag.

[0064] Test 2: Detection of elements and components of raw phosphogypsum.

[0065] Experiment 3: After the phosphogypsum is dried to a moisture content of 10% using the impurity removal device created by the present invention, it is sent to a flash kiln, the temperature is controlled between 400-600°C, and after continuous feeding and flashing treatment for 5 minutes, it is discharged from the flash kiln to obtain flash gypsum. The discharged flash gypsum is crushed by a grinder and passed through a 50-mesh sieve to obtain flash gypsum powder; and the flash gypsum powder is tested for elements and their components.

[0066] Experiment 4: After the phosphogypsum is dried to a moisture content of 5% using the impurity removal device created by the present invention, it is sent to a flash kiln, the temperature is controlled between 400-600°C, and after continuous feeding and flashing for 15 minutes, it is discharged from the flash kiln to obtain flash gypsum. The discharged flash gypsum is crushed by a grinder and passed through a 50-mesh sieve to obtain flash gypsum powder; and the flash gypsum powder is tested for elements and their components.

[0067] Test 5: The raw material barium slag and the raw material phosphogypsum were directly mixed in a mass ratio of 10:1 and subjected to harmless treatment to obtain harmless slag. The harmless slag was tested for elements and components.

[0068] Experiment 6: The raw barium slag was directly mixed with the phosphogypsum obtained in Experiment 3 at a mass ratio of 10:1 and subjected to harmless treatment to obtain harmless slag. The harmless slag was tested for elements and components.

[0069] Experiment 7: The raw material barium slag was directly mixed with the phosphogypsum obtained in Experiment 4 at a mass ratio of 10:1 and subjected to harmless treatment to obtain harmless slag. The harmless slag was tested for elements and components.

[0070] The above tests refer to "Hazardous Waste Identification Standard Leaching Toxicity" GB 5085.3-2007 to test copper, zinc, barium, lead, cadmium, total chromium, silver, beryllium, nickel, magnesium, calcium, iron, mercury, arsenic, and selenium content; refer to "GB11893-89" to test total phosphorus; refer to "GB / T15555.11-1998" to test fluoride; refer to "GB / T15555.12-1995" to test corrosiveness; refer to "JC / T1021.7-2007 Chemical Analysis Methods for Non-metallic Minerals and Rocks Part 7 Chemical Analysis Methods for Barite Ore" to test barium sulfate, sulfur trioxide, silicon dioxide, ferric oxide, aluminum oxide, calcium oxide, and magnesium oxide; refer to "Determination of Barium Carbonate in GB1614-2011" to test barium carbonate. The results of tests 1 to 7 are recorded in Table 1 below.

[0071] Table 1

[0072]

[0073]

[0074] “ND” means not detected;

[0075] “——” indicates that the corresponding elements or components are not detected due to lack of them and the relevant testing standards are not within the applicable scope.

[0076] The harmless slag obtained from Tests 5 to 7 was piled in the test room for 180 days and then used as a sample. The barium content was tested with reference to "Hazardous Waste Identification Standard Leaching Toxicity" GB 5085.3-2007; the corrosiveness was tested with reference to "GB / T15555.12-1995", and the test results were recorded in Table 2.

[0077] Table 2

[0078]

[0079] As shown in Table 1, the invention can significantly reduce the leaching toxicity of barium ions in the barium slag by directly mixing it with barium slag for harmless treatment after drying the phosphogypsum, flash burning (controlling the flash burning temperature and time) and crushing it to prepare flash gypsum, so that the pH value of the harmless slag is maintained between 6 and 9, reducing acid and alkali corrosion. As shown in Table 2, the invention can enhance the stability of the harmless slag obtained by directly mixing the phosphogypsum, flash burning (controlling the flash burning temperature and time) and crushing it to prepare flash gypsum, and then directly mixing it with barium slag for harmless treatment. After long-term stacking, no increase in leaching toxicity is found, and there is no change in acid and alkali corrosion.

[0080] Other matters not covered by the present invention may be achieved by conventional technical means with reference to the prior art or common knowledge known to those skilled in the art. For example, the aging and stirring mixing rate of the harmless treatment process of phosphogypsum directly mixed with barium slag may be operated with reference to the techniques disclosed in the prior art.

Claims

1. A method for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag, characterized in that: The following steps are involved: S1: drying the phosphogypsum in a drying tower (2) to a moisture content of ≤10%, and then sending the phosphogypsum to a flash kiln (3) for flash treatment to obtain volatile tail gas, flash gypsum and hot air; S2: sending the tail gas to a spray tower (6) and spraying it with lime water for precipitation to obtain precipitated residue and supernatant; the supernatant is returned and mixed with lime water and then sprayed on the tail gas for treatment; S3: The hot gas is returned to the drying tower (2) for heat exchange to pre-dry the phosphogypsum, and then circulated with the precipitated slag to obtain dry slag and cooling gas, which is then discharged; Alternatively, the hot air is divided into two parts, one part is returned to the drying tower (2) for heat exchange to pre-dry the phosphogypsum, and then circulates heat exchange with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is discharged; the other part is directly circulated and heat exchanged with the precipitated slag to room temperature to obtain dry slag and cooling gas, and the cooling gas is discharged; Or the hot air is directly circulated with the precipitated slag to exchange heat to room temperature, and dry slag and cooling gas are obtained, and the cooling gas is discharged; S4: The flash gypsum is crushed and packaged.

2. The method for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag as claimed in claim 1, characterized in that: In step S1, the temperature of the flash treatment is 400-600° C., and the flash time is 5-15 minutes.

3. The method for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag as claimed in claim 1, characterized in that: The pH value of the lime water is ≥10, and the mass concentration of the lime water is 10% to 15% in terms of calcium hydroxide.

4. A device for removing impurities from phosphogypsum for direct mixing and harmless treatment of barium slag, characterized in that: The invention comprises a drying tower (2) and a flash kiln (3), wherein the flash kiln (3) is provided with a feed port (3.9), a discharge port (3.10), a volatile matter discharge port (3.11) and a hot air pipe (3.3); the drying tower (2) is provided with a feed port, a discharge port, a circulation inlet and a circulation outlet; the discharge port is connected to the feed port (3.9); the volatile matter discharge port (3.11) is connected to a spray tower (6), and the spray tower (6) is connected to a precipitation tank (7); the precipitation tank (7) is connected to a clear liquid tank (10) and a heat exchange tower (8), and the clear liquid tank (10) is connected to a circulation pool (11), and the circulation pool (1 1) connected to a lime water tank (12), the circulation pool (11) is connected to the spray tower (6); the heat exchange tower (8) is connected to a dry slag tank (9); the discharge port (3.10) is connected to a crusher (4); the hot air pipe (3.3) is connected to the circulation inlet, the circulation outlet is connected to the heat exchange tower (8) and is capable of heat exchange; or the hot air pipe (3.3) is connected to the circulation inlet, the circulation outlet is connected to the heat exchange tower (8) and is capable of heat exchange, and the hot air pipe is connected to the circulation inlet; or the hot air pipe (3.3) is directly connected to the heat exchange tower (8) and is capable of heat exchange.

5. The phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag as claimed in claim 4, characterized in that: The pulverizer (4) is connected to the storage bin (5); and / or the feed port is connected to the phosphogypsum tank (1).

6. The phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag as claimed in claim 4, characterized in that: The circulation pool (11) is connected to a pH detection sensor and a concentration detector.

7. The phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag as claimed in claim 4, characterized in that: The flash kiln (3) comprises a bracket (3.6) and a flash body mounted on the bracket (3.6); the flash body comprises a combustion chamber (3.1) and a rotating chamber (3.2); the rotating chamber (3.2) runs from the left end of the combustion chamber (3.1) to the right end of the combustion chamber (3.1), and the rotating chamber (3.2) can rotate freely in the combustion chamber (3.1); the combustion chamber (3.1) is provided with a fuel port (3.4), a hot air pipe (3.3) and a blower (3.5); the rotating chamber (3.2) A left cover (3.8) is provided at the left end, and a feed port (3.9) capable of feeding phosphogypsum into the rotating chamber (3.2) is provided on the left cover (3.8); a right cover (3.7) is provided at the right end of the rotating chamber (3.2), and a volatile material discharge port (3.11) and a discharge port (3.10) are provided on the right cover (3.7); the left cover (3.8) and the right cover (3.7) are both fixed on the bracket (3.6), and the rotating chamber (3.2) can rotate freely relative to the left cover (3.8) and the right cover (3.7).

8. The phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag as claimed in claim 7, characterized in that: The combustion chamber (3.1) is provided with a slag discharge port.

9. The phosphogypsum impurity removal device for direct mixing and harmless treatment of barium slag as claimed in claim 7, characterized in that: The rotating chamber (3.2) is provided with a toothed belt, and the toothed belt can be connected to a motor and drive the rotating chamber (3.2) to rotate.

10. A flash kiln for direct mixing and harmless treatment of barium slag and phosphogypsum impurity removal flash firing, characterized in that: The invention comprises a bracket (3.6) and a flash burning body mounted on the bracket (3.6); the flash burning body comprises a combustion chamber (3.1) and a rotating chamber (3.2); the rotating chamber (3.2) runs from the left end of the combustion chamber (3.1) to the right end of the combustion chamber (3.1), and the rotating chamber (3.2) can rotate freely in the combustion chamber (3.1); the combustion chamber (3.1) is provided with a fuel port (3.4), a hot air pipe (3.3) and a blower (3.5); the left end of the rotating chamber (3.2) is provided with A left cover (3.8) is provided on the left cover (3.8) with a feed port (3.9) capable of feeding phosphogypsum into the rotating chamber (3.2); a right cover (3.7) is provided at the right end of the rotating chamber (3.2), and a volatile material discharge port (3.11) and a discharge port (3.10) are provided on the right cover (3.7); the left cover (3.8) and the right cover (3.7) are both fixed on the bracket (3.6), and the rotating chamber (3.2) can rotate freely relative to the left cover (3.8) and the right cover (3.7).

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