Device for realizing ardealite purification by impact

Abstract

The invention discloses a device for realizing ardealite purification through impinging, relates to the field of ardealite resource utilization, solves the difficult problem of recycling of a byproduct ardealite generated by preparing phosphoric acid from phosphate ore, and is characterized in that the device comprises an impinging stream calcining tank (1), a circulating aging tank (2) and a pre-drying roller (3), wherein the top of the impinging stream calcining tank (1) is connected with an air inlet of the pre-drying roller (3) through a pipeline, and the bottom of the impinging stream calcining tank (1) is connected with the top of the circulating aging tank (2) through a pipeline; the invention also provides a method for preparing high-quality beta gypsum from purified phosphogypsum by using the device provided by the invention. According to the beta gypsum powder prepared by the device and the method, the content of semi-hydrated beta gypsum is more than or equal to 90%, the content of AIII anhydrous gypsum is 0, and the content of DH dihydrate gypsum is less than or equal to 1.5%.

Description

Technical Field

[0001] The present invention relates to the field of resource utilization of phosphogypsum, and in particular to a device and method for preparing high-quality beta gypsum by using purified phosphogypsum. Background Art

[0002] Phosphogypsum is a byproduct of the wet phosphoric acid production process, in which sulfuric acid is used to decompose phosphate rock to produce phosphoric acid. The green and efficient treatment of phosphogypsum is a key link in resource recycling and utilization, and it is also a global problem. As a recyclable resource with great potential, phosphogypsum can be used in cement, gypsum building materials, chemicals, agriculture (soil conditioner) and other fields. Currently, phosphogypsum is mainly used in the building materials industry. Studies have found that after purification, the gypsum grade of phosphogypsum is higher, and the gypsum content can easily meet the technical content requirements of plaster gypsum for building materials. However, there are still great technical challenges in the preparation of high-quality β-gypsum by calcining purified phosphogypsum, especially for the control of the three phases of building plaster gypsum.

[0003] The three phases in building gypsum are key control indicators. β-type hemihydrate gypsum is used for plastering, and its quality must be strictly controlled, otherwise it is easy to have plastering quality problems, such as cracking, powdering, blooming, abnormal fluctuations in setting time, etc. Due to the different microstructures of each phase inside the building gypsum, there are obvious differences in macroscopic physical and chemical properties. Therefore, the quality and performance of building gypsum are closely related to the proportion of each component phase.

[0004] Since the formation temperature regions of some phases in calcined gypsum are intertwined, the gypsum produced under certain conditions is a mixed phase dominated by a certain phase, which may include dihydrate gypsum, hemihydrate gypsum, soluble anhydrous gypsum and anhydrous gypsum AⅡ. Crystallization water is an important guiding parameter for controlling the quality of building gypsum. Type III soluble anhydrous gypsum (AⅢ) is easy to appear when the gypsum calcination temperature is high or the heating is uneven. AⅢ has a large water demand, fast coagulation, and low strength of the hardened product. In severe cases, it will cause the wall surface to become flowery and partially de-powdered, and its content needs to be strictly controlled. The content of dihydrate gypsum (DH) is also an indicator that needs to be strictly controlled. If the content of dihydrate gypsum is too high, it will cause lightweight plaster to set quickly, and it cannot be controlled even if a large amount of gypsum retarder is added. The requirement is that the content is as low as possible. However, according to the survey of the existing gypsum calcination plant process and test data, it is difficult to require the content of dihydrate gypsum (DH) to be less than 3.0%.

[0005] Patent CN202211474829.6 discloses a method for producing gypsum board using phosphogypsum as raw material. The patent performs preliminary calcination in a hammer dryer to obtain preliminary gypsum powder; the preliminary gypsum powder is subjected to secondary calcination in a fluidized bed furnace, the calcination is more uniform, and the gypsum powder has a higher content of effective ingredients, thereby obtaining building gypsum powder. The content of hemihydrate gypsum in the obtained building gypsum powder is 81.15%; the content of dihydrate gypsum is 2.16%; the content of soluble anhydrous gypsum is 2.7%; and the content of crystal water is 5.4%.

[0006] Patent CN202211489963.3 discloses a method for rapid aging of gypsum, specifically, the calcined gypsum is subjected to a fluidized aging reactor, and the aging gas with a water content of 0.2-38% is directly contacted with the calcined gypsum under the condition of a reaction temperature of room temperature to 80°C to react, so that the anhydrous gypsum in the gypsum is quickly converted into hemihydrate gypsum, increasing the hemihydrate gypsum content in the gypsum product and improving the quality of the gypsum product. The obtained gypsum has an anhydrous gypsum content of 0 and a dihydrate gypsum content of at least 1.62%.

[0007] In the prior art, there have been reports on the research of calcining gypsum into building gypsum and obtaining building gypsum with relatively good three-phase indicators of gypsum through aging treatment, but there has never been a report on the method of preparing high-quality β-gypsum by purifying phosphogypsum. Therefore, it is an urgent problem to be solved by those skilled in the art to provide a device system and method for process intensification and rapid aging of gypsum. Summary of the invention

[0008] The main purpose of the present invention is to provide a device and method for preparing high-quality beta gypsum using purified phosphogypsum. The impinging flow strengthening technology is used to quickly remove the crystal water of the purified phosphogypsum powder that has been pre-desorbed of attached water and a small amount of crystal water in the impinging flow area, thereby reducing the amount of over-burned anhydrous gypsum in the gypsum powder while minimizing the content of dihydrate gypsum. The gypsum powder that has been rapidly calcined by the impinging flow is rapidly aged by the second impinging flow and rapidly forced to cool down to obtain high-quality beta gypsum. At the same time, the waste heat in the impinging flow calcination area is introduced into the pre-drying of the purified phosphogypsum wet powder, thereby saving energy.

[0009] The present invention is achieved through the following technical solutions.

[0010] In one aspect, the present invention provides a device for preparing high-quality beta gypsum by using purified phosphogypsum, the device comprising an impinging flow calcining tank, a circulating aging tank and a pre-drying drum. The impinging flow calcining tank comprises a settling cylinder and an impinging reaction cylinder, which are sealed and connected to form a cylinder body connected up and down, and the inner diameter of the settling cylinder is larger than that of the impinging reaction cylinder; In some implementation cases, the diameter of the sedimentation cylinder is 1.5 to 2.5 times that of the impact reaction cylinder.

[0011] In the device, the diameter of the material recovery tank (i.e., the sedimentation cylinder device) is increased at the upper part of the impact flow calcining tank, so that the particles that rise with the dehydrated steam after the impact are settled in this area, reducing the separation pressure of the internal cyclone separator and increasing the output of the device per unit time; and the rising steam containing gypsum dust after the collision is decompressed and expanded in this area, producing the effect of airflow buffering and deceleration, which is beneficial to the gas-solid separation and gypsum particle deposition.

[0012] The middle of the impact reaction cylinder is provided with two centrally symmetrical coaxial accelerating tubes, the diameter of the coaxial accelerating tubes is d The distance between the two coaxial accelerating tube nozzles is 10~300mm. L 1~4 times d The distance between the two ends of the impinging flow reaction zone is formed, and the purified phosphogypsum enters through the symmetrical coaxial accelerating tube, and then is impacted and settled in the impact reaction cylinder to prepare high-quality beta gypsum. The coaxial accelerating tube is a horizontal coaxial pipeline, and the impinging flow reaction zone is vertically symmetrically distributed in the center.

[0013] In this device, the core calcination and dehydration zone is introduced with an impact flow reaction formed by an impact flow device. The pre-dried gypsum particles transported by two high-speed hot air flows collide at high speed in the impact flow reaction zone. The dihydrate gypsum particles containing crystal water infiltrate into the reverse flow due to inertia and decelerate therein, and then accelerate in the opposite direction, which greatly enhances the drying and de-crystallization water process. The dihydrate gypsum is instantly dehydrated in the impact flow to form semi-hydrated β-gypsum powder, and the gypsum powder particles settle to the bottom of the calcination tank under the action of gravity. The dihydrate gypsum particles are instantly dehydrated in the rapid impact, which greatly reduces the long-term contact of the heat source with the dihydrate gypsum particles, resulting in overburning to form a large amount of anhydrous gypsum. The rapid collision of the dihydrate gypsum particles greatly disperses and enhances the thermal contact effect, and also greatly reduces the lack of contact between the dihydrate gypsum and the heat source, resulting in underburning, which makes the product contain more dihydrate gypsum.

[0014] A star-shaped feeder is provided near the connection end of the feed pipe and the coaxial accelerating tube to realize one-way sealed continuous feeding of phosphogypsum powder; The coaxial accelerating tube is provided with a contraction port at the far end of the feeding tube. The setting of the contraction port can form a low-pressure area at the far end of the area where the accelerated hot air accelerates the feeding gypsum particles and prevent the back pressure effect, which greatly ensures the smooth flow of the feeding gypsum particles before collision.

[0015] The bottom of the impact reaction cylinder is connected to the feed pipe of the circulation aging tank through the discharge port.

[0016] The circulating aging tank comprises an impact hydration reaction cylinder and a circulating aging cylinder; Two centrally symmetrical coaxial spray pipes are provided in the middle of the impact hydration reaction cylinder; The coaxial spray pipe is a horizontal coaxial pipe and is vertically symmetrically distributed with the impinging flow reaction zone as the center; The middle part of the impact hydration reaction cylinder is provided with a centrally symmetrical coaxial feed acceleration tube and a circulating material tube; The coaxial feed accelerating tube and circulating material tube are vertical coaxial pipes with the same diameter, and are vertically symmetrically distributed with the impinging flow reaction zone as the center.

[0017] The diameters of the coaxial feed accelerating tube and circulating material tube are d’ The distance between the coaxial feed acceleration tube and the circulating material pipe nozzle is 10~300mm. L’ 1~4 times d’ distance; The coaxial spray pipe is provided with a nozzle, the diameter of the nozzle is 0.1-2 mm; the spacing between the two nozzles L’’ = L’ .

[0018] In this device, the impact hydration reaction cylinder at the upper part of the circulation aging tank is provided with a coaxial vertical acceleration tube and a feed circulation tube, so that the gypsum powder after de-crystallization water is impacted and mixed for the second time, and hydrated and impacted with the coaxial spray tube in the vertical direction, so that a very small amount of anhydrous gypsum formed in the impact calcination tank is quickly hydrated into semi-hydrated gypsum, and the gypsum powder after impact hydration falling to the bottom of the inner cylinder continues to be further circulated and hydrated through the circulation pipe, which fully ensures that a very small amount of over-burned gypsum powder is hydrated into semi-hydrated β-gypsum.

[0019] The feeding pipe is provided with a star-shaped feeder near the feeding acceleration pipe end, and its function is the same as above.

[0020] The feed accelerating tube is provided with a contraction port at the far feed tube end, and its function is the same as above.

[0021] The lower part of the impact hydration reaction cylinder is provided with a tapered annular tube which is wider at the top and narrower at the bottom, and the opening diameter of the lower part of the tapered annular tube is larger than the outer tube diameter of the circulating material tube; The conical annular tube allows the impacted material to sink down to the bottom of the inner tube along the tube wall close to the circulating material tube to participate in the circulation instead of directly dispersing and overflowing to the outer tube discharge tube.

[0022] An exhaust port is arranged on the upper part of the impact hydration reaction cylinder, which is used to exhaust the ethanol vapor or water-containing ethanol vapor generated by evaporation of the hydrating agent after hydration.

[0023] The circulating aging cylinder is composed of an outer cylinder and an inner cylinder of a double-layer structure. The bottoms of the outer cylinder and the inner cylinder are fixedly connected by circulating air pipes to form a jacket cavity between the outer cylinder and the inner cylinder for temporarily storing the circulating hydrated materials.

[0024] The cross section of the upper opening of the inner cylinder is in the same horizontal plane as the cross section of the circular baffle opening, so that the fully hydrated and aged gypsum powder that has been circulated and enriched to a certain amount can stably overflow the cavity between the inner and outer cylinders.

[0025] The cross section of the upper opening of the inner cylinder is formed at a certain distance by the inclination of the circular baffle, so that a material flow space is formed between the inner cylinder and the impact hydration reaction cylinder; The cross section of the upper opening of the inner cylinder has the same diameter as the maximum cross section of the impact hydration reaction cylinder.

[0026] A discharge port is provided at the lower part of the outer cylinder; A screen is provided at the connection between the top of the circulating air pipe and the bottom of the inner cylinder. In some cases, the aperture of the screen is 20-60 μm, and its main function is to prevent the gypsum powder material from escaping into the circulating air pipe before the circulating air pipe is turned on for compressed air circulation; There is a gap between the circulating material pipe and the screen, so that a stable and orderly circulating feed is formed between the circulating material and the circulating gas; The circulating material pipe penetrates the impact hydration reaction cylinder and the inner cylinder and is fixed on the inner cylinder by a bracket.

[0027] The discharge port of the pre-drying drum is connected to two centrally symmetrical coaxial accelerating tubes through symmetrical feeding tubes, so that the materials dried in the pre-drying drum enter the coaxial accelerating tubes through the feeding tubes.

[0028] The top of the settling cylinder is provided with a cyclone separator; the top of the cyclone separator is connected to the air inlet of the pre-drying drum through a pipeline; the pre-drying drum comprises a cylinder, a feed hopper, an air inlet, an exhaust port and a discharge port; in this device, the cyclone separator on the upper part of the impact calcining tank is connected to the pre-drying drum, and the evaporation waste heat in the impact calcining tank is introduced into the pre-drying drum from the discharge port, and the waste heat steam flow is in countercurrent contact with the wet purified phosphogypsum powder, making full use of the waste heat of the system, and the waste heat is introduced into the tail gas dust removal system after pre-drying and dehydrating the wet purified phosphogypsum powder; another function of this structure is to pass the airflow with a small amount of gypsum dust remaining after cyclone separation and countercurrent contact with the wet phosphogypsum powder, so that the small amount of phosphogypsum powder taken out of the calcining tank can be intercepted and settled in the pre-drying drum. It plays the dual role of utilizing waste heat and collecting gypsum dust.

[0029] The discharge port described in the present invention is connected with the feed pipe through a pipeline.

[0030] In another aspect, the present invention provides a method for preparing high-quality beta gypsum by using purified phosphogypsum, the method being carried out using the apparatus described in the first aspect, the method comprising: (1) The dried purified phosphogypsum powder is respectively introduced into two centrally symmetrical coaxial accelerating tubes, and is subjected to impact removal of crystal water in the impinging flow reaction zone formed in the impinging flow calcining tank; the gypsum powder without crystal water is dehydrated gypsum powder, and the dehydrated gypsum powder falls to the bottom of the tank to realize the recovery of the dehydrated gypsum powder; (2) The dehydrated gypsum powder is accelerated by compressed air and continuously introduced into a feed acceleration tube. After a period of operation, the circulating material in the circulating material tube, which is also accelerated by compressed air, collides in the impact zone. At the same time, a hydrating agent is sprayed into the impact zone through a coaxial spray tube. After circulating hydration and aging, β-gypsum powder is obtained.

[0031] The purified phosphogypsum dried in step (1) is a material obtained by drying dihydrate gypsum containing 5-20% of attached water at 140-160°C.

[0032] In the step (1), the coaxial accelerating tube contains hot air at a temperature of 200-450° C.; the hot air enters at a speed of 15-40 m / s, and the feed rate of the dried purified phosphogypsum is 0.1-10 kg / s, so that the purified phosphogypsum reacts at 160-180° C. in the impinging flow reaction zone.

[0033] In some embodiments, the wet powder of phosphogypsum after flotation purification of the present invention is obtained by processing using the technology disclosed in patent CN202310118177.0. The phosphogypsum concentrate powder obtained by the treatment is directly used as the raw material of the present invention after filtering operation.

[0034] The heat generated after impact removal of crystal water in the step (1) is recycled to prepare the dried purified phosphogypsum. In the present invention, the system waste heat after impact calcination is introduced into the pre-drying drum in reverse flow, and the wet purified phosphogypsum powder is pre-dried to remove the attached water and a small amount of crystal water, thereby making full use of the system waste heat, saving energy, and the pre-dried gypsum powder is conducive to impact removal of crystal water.

[0035] The dehydrated gypsum powder has a material temperature of 140°C to 170°C and is continuously introduced into the feed acceleration tube through compressed air. The compressed air has a room temperature and a flow rate of 15 to 40 m / s. The compressed air in the circulating material pipe has a room temperature and a flow rate of 15 to 40 m / s. The feed rate of the dehydrated gypsum powder is 0.1 to 10 kg / s.

[0036] The hydrating agent is 65% to 95% ethanol, more preferably 70% to 95% ethanol, and further preferably 80% to 95% ethanol.

[0037] The feeding amount of the hydrating agent is 0.1 to 1 times the mass of the dehydrated gypsum powder, so as to ensure that the AIII anhydrous gypsum in the dehydrated gypsum powder is all quickly hydrated into hemihydrated gypsum powder, and not hydrated into dihydrated gypsum powder.

[0038] It is worth noting that the hydrating agent used in the present invention is 65% to 95% alcohol. At this time, the alcohol aqueous solution is in an associated state. When the calcined gypsum is mixed with the alcohol solution, the DH dihydrate gypsum does not participate in the reaction, and the AIII anhydrous gypsum participates in the reaction unconditionally. The AIII anhydrous gypsum can cut the hydrogen bond between water and ethanol, capture water molecules and combine with them to form semi-hydrated gypsum, while the HH semi-hydrated gypsum has no ability to cut hydrogen bonds. HH can only find water molecules in the solution that are in a free state to combine, or although in an associated state, it has the properties of free water to combine. The alcohol at this concentration is in a completely associated state, and there is no free water. After the coaxial spray tube sprays and the gypsum powder in the impact state, it is vertically impacted and contacted. The very small amount of AIII anhydrous gypsum produced by the calcination system quickly contacts the alcohol solution to capture water molecules for hydration, and is aged into semi-hydrated gypsum, while the semi-hydrated gypsum of the calcination system itself does not absorb water molecules in the alcohol solution to hydrate into dihydrated gypsum. Compared with conventional technical means, such as calcining gypsum and then aging it in the open air for 1 to 7 days, or aging it by introducing water vapor, conventional technical means will more or less cause the system anhydrous gypsum to absorb water and generate excess dihydrate gypsum during the aging and hydration of the anhydrous gypsum due to control difficulties. The present invention uses associated water, and a very small amount of anhydrous gypsum produced by the calcination system can be hydrated into hemihydrate gypsum without producing dihydrate gypsum. In the present invention, the ethanol deprived of water molecules is discharged through the upper exhaust port and enters the dust removal and alcohol recovery system for dust removal, recovery and reuse of alcohol.

[0039] The invention introduces normal temperature compressed air into the aging tank, so that the high temperature gypsum powder after calcination is hydrated with the hydrating agent, and then the gypsum powder is quickly cooled down by the impact of normal temperature compressed air, and a certain air flow crushing effect is achieved through the secondary impact of compressed air. The gypsum powder particles are crushed by mutual impact to form uniform fine gypsum powder. The gypsum powder after aging and cooling overflows into the cavities of the inner and outer cylinders, and high-quality commercial-grade beta gypsum powder is obtained through a continuous discharging system.

[0040] The gypsum powder obtained after hydration and aging in the step (2) falls to the bottom to participate in the circulation. After the circulating material reaches the height of the overflow port, it overflows continuously, accumulates in the cavity and is discharged continuously through the discharge port to obtain β gypsum powder.

[0041] The prepared beta gypsum powder has a content of hemihydrate gypsum of ≥90%, anhydrous gypsum of 0, and a content of dihydrate gypsum of ≤1.5%.

[0042] In some cases, the β-gypsum powder prepared by the present invention has a hemihydrate gypsum content of ≥95%, an anhydrous gypsum content of 0, and a dihydrate gypsum content of ≤1.0%.

[0043] In some cases, the β-gypsum powder prepared by the present invention has a hemihydrate gypsum content of ≥98%, an anhydrous gypsum content of 0, and a dihydrate gypsum content of ≤0.5%.

[0044] The method of the present invention is prepared by using the device.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects: (1) The device provided by the present invention provides an impact flow reaction zone to quickly remove crystal water from the pre-dried purified phosphogypsum powder, thereby ensuring that as little residual dihydrate gypsum as possible and producing as little anhydrous gypsum as possible from the calcined gypsum powder.

[0047] (2) The impact calcination of the present invention causes the dihydrate gypsum to be rapidly dehydrated to form hemihydrate β-gypsum, with little residual dihydrate gypsum. A very small amount of overburned anhydrous gypsum is rapidly aged by a hydrating agent of a special concentration to become hemihydrate β-gypsum, and then impact-cooled by compressed air. The resulting β-gypsum powder is high in quality, does not contain anhydrous gypsum, and has a dihydrate gypsum content lower than the industry average. The product has a blue light whiteness of 78 or above, and is more preferably 79 or above.

[0048] (3) The impact calcination dehydration time of the present invention is short, and the dehydration is completed at the moment of impact. The average residence time of the material is less than 10 seconds. The anhydrous gypsum in the circulation aging tank is quickly hydrated into hemihydrate gypsum. The circulation aging time is less than 10 minutes, which greatly shortens the preparation time of β-hemihydrate gypsum. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a device for preparing high-quality beta gypsum by using purified phosphogypsum provided in Example 1; Among them, 1-impact flow calcining tank, 2-circulation aging tank, 3-pre-drying drum, 11-sedimentation cylinder, 12-impact reaction cylinder, 13-cyclone separator, 14-coaxial acceleration tube, 15-feeding pipe, 16-star feeder, 17-contraction port, 18-discharge port, 21-impact hydration reaction cylinder, 22-circulation aging cylinder, 23-coaxial spray tube, 24-coaxial feeding acceleration tube, 25-circulation pipe, 241-feeding pipe, 242-star feeder, 243 contraction port, 26-conical ring pipe, 27-exhaust port, 221-outer cylinder, 222-inner cylinder, 223-circulation air pipe, 224-discharge port, 225-screen, 251-bracket, 31-cylinder, 32-feed hopper, 33-air inlet, 34-exhaust port, 35-discharge port.

[0050] Figure 2 This is a partial enlarged view of the conical ring tube.

[0051] Figure 3 A flow chart of a method for preparing high-quality β-gypsum using purified phosphogypsum is provided for Application Example 1.

[0052] Figure 4 This is the gypsum blue light whiteness test sample obtained in Example 5.

[0053] Figure 5 The left, middle and right are the products obtained in Example 5, Example 6 and Example 7 respectively. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below by specific implementation methods. Those skilled in the art should be aware that the embodiments are only to help the technicians understand the present invention and should not be regarded as specific limitations of the present invention.

[0056] Example 1 This embodiment provides a device for preparing high-quality beta gypsum by using purified phosphogypsum, such as Figure 1 , 2 As shown, the device comprises an impinging flow calcining tank 1, a circulating aging tank 2 and a pre-drying drum 3, wherein the impinging flow calcining tank 1 comprises a settling cylinder 11 and an impinging reaction cylinder 12, and the bottom of the settling cylinder 11 is fixedly connected to the upper part of the impinging reaction cylinder 12; Two centrally symmetrical coaxial accelerating tubes 14 are provided in the middle of the impact reaction cylinder 12. The diameter d of the coaxial accelerating tubes 14 is 10 mm. The distance L between the nozzles of the two coaxial accelerating tubes 14 is 3 times the distance d, forming an impact flow reaction zone. The coaxial accelerating tubes 14 are horizontal coaxial pipes, and the impact flow reaction zone is centrally and vertically symmetrically distributed, which is used to allow purified phosphogypsum to enter through the symmetrical coaxial accelerating tubes 14 and then impact in the impact reaction cylinder 12, and then be hydrated and precipitated by corresponding hydration and aging devices to prepare high-quality β-gypsum.

[0057] A star-shaped feeder 16 is provided at the end close to the connection between the feed tube 15 and the coaxial accelerating tube 14 .

[0058] The coaxial accelerating tube 14 is provided with a contraction opening 17 at the far feed tube end.

[0059] The diameter of the sedimentation cylinder 11 is twice that of the impact reaction cylinder 12 .

[0060] The bottom of the impact reaction cylinder 12 is connected to the feed pipe 241 of the circulation aging tank 2 through the discharge port 18.

[0061] The circulating aging tank 2 comprises an impact hydration reaction cylinder 21 and a circulating aging cylinder 22 , and the bottom of the impact hydration reaction cylinder 21 is fixedly and sealedly connected with the upper part of the circulating aging cylinder 22 .

[0062] The middle of the impact hydration reaction cylinder 21 is provided with two centrosymmetric coaxial spray pipes 23; The coaxial spray pipe 23 is a horizontal coaxial pipe and is vertically symmetrically distributed with the impinging flow reaction zone as the center; The middle part of the impact hydration reaction cylinder 21 is provided with a centrally symmetrical coaxial feed acceleration tube 24 and a circulating material tube 25; The coaxial feed accelerating tube 24 and circulating material tube 25 are vertical coaxial pipes with the same diameter, and are vertically symmetrically distributed with the impinging flow reaction zone as the center.

[0063] The diameters of the coaxial feed accelerating tube 24 and the circulating material tube 25 are d’ The distance between the nozzles of the coaxial feed accelerating tube 24 and the circulating material tube 25 is 10 mm. L’ 3 times d’ distance; The coaxial spray pipe 23 is provided with a nozzle, the diameter of the nozzle is 0.2 mm; the spacing between the two nozzles L’ '= L’ .

[0064] The feeding pipe 241 is provided with a star-shaped feeder 242 at the end close to the feeding acceleration pipe 24; The feed accelerating tube 24 is provided with a contraction opening 243 at the far feed tube end; The impact hydration reaction cylinder 21 is provided with a tapered annular tube 26 which is wide at the top and narrow at the bottom. The opening diameter of the tapered annular tube 26 at the bottom is larger than the outer tube diameter of the circulating material tube 25. An exhaust port 27 is disposed on the upper portion of the impact hydration reaction cylinder 21 .

[0065] The circulating aging cylinder 22 is composed of an outer cylinder 221 and an inner cylinder 222 of a double-layer structure. The bottoms of the outer cylinder 221 and the inner cylinder 222 are fixedly connected by a circulating air pipe 223, so that a jacket cavity is formed between the outer cylinder 221 and the inner cylinder 222.

[0066] The cross section of the upper opening of the inner cylinder 222 is in the same horizontal plane as the opening of the lower portion of the conical annular tube 26 , and a material flow space is formed between the inner cylinder 222 and the impact hydration reaction cylinder 21 .

[0067] The cross section of the upper opening of the inner cylinder 222 has the same diameter as the maximum cross section of the impact hydration reaction cylinder 21 .

[0068] A discharge port 224 is disposed at the lower portion of the outer cylinder 221 .

[0069] A screen 225 is provided at the connection between the top of the circulating air pipe 223 and the bottom of the inner tube 222, and the aperture of the screen 225 is 45 μm.

[0070] There is a gap between the circulating material pipe 25 and the screen 225 .

[0071] The circulating material pipe 25 penetrates the impact hydration reaction cylinder 21 and the inner cylinder 222 and is fixed on the inner cylinder 222 by a bracket 251 .

[0072] The discharge port 35 of the pre-drying drum 3 is connected to two centrally symmetrical coaxial accelerating tubes 14 via symmetrical feed pipes 15 .

[0073] A cyclone separator 13 is disposed on the top of the sedimentation cylinder 11 .

[0074] The top of the cyclone separator 13 is connected to the air inlet 33 of the pre-drying drum 3 through a pipeline, and is used to provide the heat required for drying and purifying the gypsum inside the pre-drying drum 3; the pre-drying drum 3 includes a cylinder 31, a feed hopper 32, an air inlet 33, an exhaust port 34 and a discharge port 35; the cylinder 31 is used for pre-drying the wet phosphogypsum product, the feed hopper 32 is used for the feeding process of the wet phosphogypsum, the air inlet 33 and the exhaust port 34 are used for the gas generated by the impact flow calcining tank 1 to enter the pre-drying drum to dry the wet phosphogypsum, and the gas generated after drying is discharged through the exhaust port. The discharge port 35 is for the generated dry phosphogypsum to enter the coaxial acceleration tube 14 through the discharge port 35 through the pipeline.

[0075] Example 2 This embodiment provides a device for preparing high-quality β-gypsum by using purified phosphogypsum. Except that the diameter of the upper sedimentation cylinder 11 is 2.5 times that of the lower impact reaction cylinder 12, other conditions are the same as those in Example 1.

[0076] After the application is expanded to 2.5 times, the space is increased, the sedimentation effect of the dehydrated phosphogypsum powder obtained in the impact area is improved, and the separation load of the cyclone separator is reduced.

[0077] Example 3 This embodiment provides a device for preparing high-quality beta gypsum by using purified phosphogypsum. d The distance between the nozzles of the two coaxial accelerating tubes 14 is 100 mm. L 2.5 times d The distance between the coaxial feed accelerating tube 24 and the circulating material tube 25 is d’ The distance between the nozzles of the coaxial feed accelerating tube 24 and the circulating material tube 25 is 100 mm. L’ 2.5 times d’ The other conditions are the same as those in Example 1.

[0078] This application expands the pipe diameter to 100mm and the spacing L and L’ After being reduced to 2.5 times, the corresponding processing volume increases, and the impact mixing effect is basically the same as that in Example 1. However, when it is gradually reduced to 2.0 times, the collision resistance becomes larger due to the closer collision, and the mixing effect becomes worse.

[0079] Example 4 This embodiment provides a device for preparing high-quality beta gypsum by purifying phosphogypsum. The diameter of the coaxial accelerating tube 14 is d The distance between the nozzles of the two coaxial accelerating tubes 14 is 50 mm. L 4 times d The distance between the coaxial feed accelerating tube 24 and the circulating material tube 25 is d’ The distance between the nozzles of the coaxial feed accelerating tube 24 and the circulating material tube 25 is 50 mm. L’ 4 times d’ The other conditions are the same as those in Example 1.

[0080] This application expands the pipe diameter to 50mm and the spacing L and L’ After increasing to 4 times, the corresponding processing volume increases, and the impact mixing is basically the same as in Example 1. However, when it is gradually increased to 4.5 times, the impact force becomes weaker due to the farther impact, so that the mixing effect becomes worse.

[0081] Example 5 The purified phosphogypsum wet powder used in this embodiment is obtained by the treatment method disclosed in Example 1 of patent CN202310118177.0. Data analysis of the obtained purified phosphogypsum wet powder shows that the crystal water is 19.98%, the purity of dihydrate gypsum is 95.46%, and in fact, it also contains 16.47% of attached water.

[0082] This embodiment provides a method for preparing high-quality beta gypsum by using purified phosphogypsum. The method is carried out using the device provided in Example 1. The process is as follows: Figure 4 As shown, the method includes: (1) The wet powder of phosphogypsum after flotation purification is continuously fed into the pre-drying drum through the feed hopper for countercurrent dehydration and drying. The steam temperature in the pre-drying drum is 150°C. The pre-dried gypsum powder is dried to a content of less than 2% of attached water to obtain pre-dried gypsum powder.

[0083] In some implementation cases, the drying heat source (steam heat) of the pre-drying drum comes from the separated dehydrated steam of the impact flow calcining tank in step (2). The wet tail gas generated after drying has a temperature of 100° C. and is discharged into the tail gas dust removal treatment system through the exhaust port.

[0084] In some implementation cases, without limitation and heat application, the following steps can be achieved by simply drying the wet powder of phosphogypsum after flotation purification to a content of attached water less than 2%.

[0085] (2) introducing the pre-dried gypsum powder obtained in step (1) into the corresponding coaxial accelerating tube through a symmetrical pipeline and a star-shaped feeder, and performing impact de-crystallization water in the impinging flow reaction zone formed in the impinging flow calcining tank; the gypsum powder from which the crystallization water is removed is the dehydrated gypsum powder; The coaxial accelerating tube contains hot air at a temperature of 300°C; the hot air enters at a speed of 18m / s; the hot air system is a hot air gas furnace; the feed rate of purified and dried phosphogypsum is 8.5kg / s, so that the purified phosphogypsum reacts at 170-175°C in the impinging flow reaction zone. The impinging calcination dehydration time is short, the dehydration is completed at the moment of impact, and the average residence time of the material is 5 seconds.

[0086] The obtained dehydrated gypsum powder falls to the bottom of the tank to obtain dehydrated gypsum powder, and the material temperature of the dehydrated gypsum powder is 150°C.

[0087] In some embodiments, The dust-laden gas after impact removal of crystal water is introduced into the cyclone separator in the drum for dust removal after the dust is settled in the sedimentation area, and then introduced into the pre-drying drum for pre-drying of wet phosphogypsum powder.

[0088] (3) The dehydrated gypsum powder obtained in step (1) is accelerated by compressed air and continuously introduced into a feed acceleration tube. After a period of operation, the circulating material in the circulating material tube, which is also accelerated by compressed air, collides in the impact zone. At the same time, a hydrating agent is sprayed into the impact zone through a coaxial spray tube. After circulating hydration and aging, β-gypsum powder is obtained.

[0089] The operation for a period of time refers to the process in which the dehydrated gypsum powder continuously enters from the feed acceleration pipe, collides with the compressed air from the circulating material pipe, and then falls along the conical ring pipe to the bottom of the inner cylinder, thereby realizing the air compression process of the circulating material pipe.

[0090] The compressed air temperature is room temperature, and the flow rate is 40m / s; the compressed air temperature in the circulating material pipe is room temperature, and the flow rate is 40m / s; the feed amount of dehydrated gypsum powder is 8.0kg / s. The hydrating agent is 95% ethanol, and the feed amount of the hydrating agent is 0.1 times the mass of the dehydrated gypsum powder. In the above, during the cyclic aging, anhydrous gypsum is quickly hydrated to hemihydrate gypsum, and the cyclic aging time is 8.5 minutes.

[0091] In some implementation cases, the gypsum powder after hydration, aging and impact falls to the bottom of the inner tube to participate in the circulation, and the evaporated gas of the hydrating agent is discharged through the upper discharge port and enters the hydrating agent recovery system.

[0092] (4) After the circulating material in step (3) reaches the height of the overflow port, it continuously overflows into the outer cylinder cavity. After the material accumulates in the outer cylinder cavity, it is continuously discharged through the discharge port to obtain β-gypsum powder.

[0093] Example 6 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum. The method is carried out using the device provided in Example 3, and other methods are the same as those in Example 5.

[0094] Example 7 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum. The method is carried out using the device provided in Example 4, and other methods are the same as those in Example 5.

[0095] The appearance of the products obtained in Examples 5, 6 and 7 is as follows: Figure 5 As shown, it can be seen that the sample has uniform particle size and high whiteness.

[0096] Example 8 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum, except that the hot air flow rate in step (2) is 35 m / s.

[0097] Except that the compressed air in step (4) is at room temperature and has a flow rate of 15 m / s, other conditions are the same as those in Example 5.

[0098] Example 9 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum. Except that the impact zone temperature in step (2) is 180° C., other conditions are the same as those in Example 5.

[0099] Example 10 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum. Except that the hydrating agent described in step (4) is 65% alcohol, other conditions are the same as those in Example 5.

[0100] Embodiment 11 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum, except that the hot air flow rate in step (2) is 10 m / s. Other conditions are the same as those in Example 5.

[0101] Example 12 This embodiment provides a method for preparing high-quality β-gypsum using purified phosphogypsum, except that the purified phosphogypsum in step (2) is reacted at 140° C. in the impinging flow reaction zone. Other conditions are the same as those in Example 5.

[0102] Example 13 This embodiment provides a method for preparing high-quality beta gypsum by using purified phosphogypsum, except that the hydrating agent in step (3) is 50% ethanol. Other conditions are the same as those in Example 5.

[0103] Embodiment 14 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum, except that the hydrating agent in step (3) is water vapor. Other conditions are the same as those in embodiment 5.

[0104] Embodiment 15 This embodiment provides a method for preparing high-quality β-gypsum by using purified phosphogypsum, except that the hydrating agent is not sprayed in step (3). Other conditions are the same as those in Example 5.

[0105] In order to better illustrate the beneficial technical effects of the present invention, a gypsum three-phase analyzer is used to perform gypsum three-phase analysis on the corresponding case samples, and the analysis data are as follows:

[0106] In summary, the device and method for preparing high-quality β-gypsum by purifying phosphogypsum provided by the present invention have high-quality β-gypsum and good promotion and application value.

[0107] The process parameters (such as temperature, hot air gas flow rate, hydrating agent concentration, etc.) of the present invention can realize the method with upper and lower limits and interval values, and the embodiments are not listed one by one here.

[0108] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A device for purifying phosphogypsum by impact, characterized in that: The device comprises an impinging flow calcining tank (1), a circulating aging tank (2) and a pre-drying drum (3). The impinging flow calcining tank (1) comprises a sedimentation cylinder (11) and an impinging reaction cylinder (12); Two centrally symmetrical coaxial accelerating tubes (14) are provided in the middle of the impact reaction cylinder (12) to form an impact flow reaction zone; the purified phosphogypsum is introduced through the symmetrical coaxial accelerating tubes (14) and then impacted and settled in the impact reaction cylinder (12) to prepare high-quality β-gypsum.

2. The device for purifying phosphogypsum by impact according to claim 1, characterized in that: A star-shaped feeder (16) is provided at the end proximal to the connection between the feed tube (15) and the coaxial accelerating tube (14); The coaxial accelerating tube (14) is provided with a contraction opening (17) at the far end of the feeding tube; The coaxial accelerating tube (14) is a horizontal coaxial pipeline, which is vertically symmetrically distributed around the center and has the same tube diameter; The bottom of the impact reaction cylinder (12) is connected to the feed pipe (241) of the circulation aging tank (2) via the discharge port (18).

3. The device for purifying phosphogypsum by impact according to claim 2, characterized in that: The tube diameter d of the coaxial accelerating tube (14) is 10 to 300 mm, and the distance L between the nozzles of the two coaxial accelerating tubes (14) is 1 to 4 times the distance d; The diameter of the sedimentation cylinder (11) is 1.5 to 2.5 times that of the impact reaction cylinder (12).

4. The device for purifying phosphogypsum by impact according to claim 2, characterized in that: The circulating aging tank (2) comprises an impact hydration reaction cylinder (21) and a circulating aging cylinder (22); The middle of the impact hydration reaction cylinder (21) is provided with two centrally symmetrical coaxial spray pipes (23); The coaxial spray pipe (23) is a horizontal coaxial pipe, the center of which is vertically symmetrically distributed and forms an impinging flow reaction zone; The impact hydration reaction cylinder (21) is provided with a centrally symmetrical coaxial feed acceleration tube (24) and a circulating material tube (25) in the middle; The coaxial feed acceleration tube (24) and the circulating material tube (25) are vertical coaxial pipes with the same pipe diameter, and are vertically symmetrically distributed at the center to form an impingement flow reaction zone.

5. The device for purifying phosphogypsum by impact according to claim 4, characterized in that: The diameter d' of the coaxial feeding acceleration tube (24) and the circulating material tube (25) is 10 to 300 mm, and the distance L' between the nozzles of the coaxial feeding acceleration tube (24) and the circulating material tube (25) is 1 to 4 times the distance d'; The coaxial spray pipe (23) is provided with a nozzle, the nozzle diameter is 0.1-2 mm; the distance between the two nozzles is L''=L'; The circulating aging cylinder (22) is composed of an outer cylinder (221) and an inner cylinder (222) of a double-layer structure. The bottoms of the outer cylinder (221) and the inner cylinder (222) are fixedly connected via a circulating air pipe (223) to form a jacket cavity between the outer cylinder (221) and the inner cylinder (222).

6. The device for purifying phosphogypsum by impact according to claim 2, characterized in that: The feeding pipe (241) is provided with a star-shaped feeder (242) at the end close to the feeding acceleration pipe (24); The feed accelerating tube (24) is provided with a contraction opening (243) at the far feed tube end. The impact hydration reaction cylinder (21) is provided with a tapered annular tube (26) at the bottom, which is wider at the top and narrower at the bottom. The opening diameter at the bottom of the tapered annular tube (26) is larger than the outer tube diameter of the circulating material tube (25). An exhaust port (27) is provided at the upper portion of the impact hydration reaction cylinder (21).

7. The device for purifying phosphogypsum by impact according to claim 5, characterized in that: The cross section of the upper opening of the inner cylinder (222) and the lower opening of the conical annular tube (26) are on the same horizontal plane, and a material flow space is formed between the inner cylinder (222) and the impact hydration reaction cylinder (21); The cross section of the upper opening of the inner cylinder (222) has the same diameter as the maximum cross section of the impact hydration reaction cylinder (21).

8. The device for purifying phosphogypsum by impact according to claim 7, characterized in that: A discharge port (224) is provided at the lower portion of the outer cylinder (221); A screen (225) is provided at the connection between the top of the circulating air pipe (223) and the bottom of the inner cylinder (222); There is a gap between the circulating material pipe (25) and the screen (225); The circulating material pipe (25) penetrates the impact hydration reaction cylinder (21) and the inner cylinder (222), and is fixed to the inner cylinder (222) by a bracket (251).

9. The device for purifying phosphogypsum by impact according to claim 1, characterized in that: The discharge port (35) of the pre-drying drum (3) is connected to two centrally symmetrical coaxial accelerating tubes (14) via symmetrical feed pipes (15).

10. The device for purifying phosphogypsum by impact according to claim 9, characterized in that: A cyclone separator (13) is provided on the top of the sedimentation cylinder (11); The top of the cyclone separator (13) is connected to the air inlet (33) of the pre-drying drum (3) through a pipeline; the pre-drying drum (3) comprises a cylinder (31), a feed hopper (32), an air inlet (33), an air outlet (34) and a discharge port (35).

Images