CN111874884B - Defluorination method and system for wet-process phosphoric acid - Google Patents
Defluorination method and system for wet-process phosphoric acid Download PDFInfo
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- CN111874884B CN111874884B CN202010716259.1A CN202010716259A CN111874884B CN 111874884 B CN111874884 B CN 111874884B CN 202010716259 A CN202010716259 A CN 202010716259A CN 111874884 B CN111874884 B CN 111874884B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
- C01B25/237—Selective elimination of impurities
- C01B25/2372—Anionic impurities, e.g. silica or boron compounds
- C01B25/2375—Fluoride or fluosilicate anion
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/01—Treating phosphate ores or other raw phosphate materials to obtain phosphorus or phosphorus compounds
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
- C01B25/235—Clarification; Stabilisation to prevent post-precipitation of dissolved impurities
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The embodiment of the invention provides a defluorination method and a defluorination system for wet-process phosphoric acid, belonging to the technical field of phosphoric acid production. The method comprises the following steps: adding phosphorus ore pulp into a reaction kettle, uniformly spraying sulfuric acid and reaction liquid from the reaction kettle on the surface of a defluorination filler in a reaction tower, sending tail gas generated by the reaction kettle into the reaction tower to the lower part of the defluorination filler, carrying out defluorination by countercurrent contact between the spray liquid and the tail gas on the defluorination filler, and returning the reaction liquid after defluorination to the reaction kettle for continuous reaction, wherein the tail gas of the reaction tower is sent to an absorption tower for fluorine recovery. According to the invention, the reaction liquid and sulfuric acid are mixed and reacted on the surface of the defluorinated filler, so that the surface reaction area is greatly increased, the sulfuric acid reacts with the fluorine-containing reaction liquid to generate heat, the generated fluorine-containing steam hardly contacts with the liquid in the reaction kettle, and meanwhile, the countercurrent contact between the high-temperature steam generated by the reaction kettle and the reaction liquid on the defluorinated filler is also beneficial to fluorine overflow; the recovery rate of fluorine is greatly improved and can reach more than 18 percent, and the recovery rate can be improved by more than 80 percent.
Description
Technical Field
The invention belongs to the technical field of phosphoric acid production, and particularly relates to a defluorination method and a defluorination system for wet-process phosphoric acid.
Background
Fluorine is an extremely reactive element, called "naughty child" in the chemical world. However, fluorine, once combined with other elements, becomes a compound having "high safety performance" which is resistant to heat and difficult to attack by drugs and solvents, and the fluorine compound is chemically stable and has a strong nonmetallic property. Fluorine only exists in the form of minerals, and the main industrially fluorine-containing minerals are fluorite and fluorapatite. Fluorite has the chemical formula (CaF) 2 ) The fluorine-containing fluorescent powder has various colors and is distributed in a large quantity all over the world, and is a main source of fluorine; the exploitation of fluorite ore is the biggest source of global fluorine, and the reserves of fluorite ore in China gradually decrease due to long-term exploitation, which means that the problem of resource shortage of fluorite ore must be considered. The phosphorus ore associated fluorine resource reserve in China is equivalent to 13.67-16.71 times of the established fluorite reserve in China, the amount of phosphorus ore mined per year is 5000 or more ten thousand tons, associated fluorine is 150 or more ten thousand tons, most of the phosphorus ore cannot be recycled, the loss amount of fluorine is far greater than the total amount of fluorine in the current-year fluorite demand in China, the phosphorus ore and the fluorite are non-renewable resources, and the effective utilization of the fluorine resources is a necessary choice for sustainable development of fluorine chemical industry. The method is that the fluosilicic acid is absorbed by water to generate fluosilicic acid, and then the fluosilicic acid is used for producing other products, so that the associated fluorine resource of the phosphorite is recovered.
The existing defluorination process is as follows: the phosphorus ore pulp reacts with sulfuric acid in a reaction kettle, tail gas generated by the reaction is sent to an absorption tower for recycling fluorine, and spray water in the absorption tower is usually used for recycling fluorine in the form of fluosilicic acid.
The applicant found that the recovery rate of fluorine in the process of producing phosphoric acid by reacting a phosphorus ore slurry with sulfuric acid by the above method was only about 10%. Thus, in phosphoric acid synthesis, we will face how to reduce fluorine or other compounds of fluorine into phosphoric acid and phosphogypsum, and recycle a large amount of fluorine in the form of fluosilicic acid.
Disclosure of Invention
The embodiment of the invention provides a defluorination method and a defluorination system for wet-process phosphoric acid. The technical scheme is as follows:
in one aspect, an embodiment of the present invention provides a defluorination method for wet-process phosphoric acid, which includes: adding phosphorus ore pulp into a reaction kettle 5, uniformly spraying sulfuric acid and reaction liquid from the reaction kettle 5 on the surface of a defluorination filler 11 in a reaction tower 10, sending tail gas generated by the reaction kettle 5 into the reaction tower 10 to the position below the defluorination filler 11, carrying out defluorination by countercurrent contact between the spray liquid and the tail gas on the defluorination filler 11, refluxing the defluorination reaction liquid to the reaction kettle 5 for continuous reaction, obtaining defluorination phosphoric acid by the reaction kettle 5 after the reaction is finished, and sending the tail gas of the reaction tower 10 into an absorption tower 17 for fluorine recovery.
Further, in the embodiment of the invention, a reaction liquid spray head 12 and a sulfuric acid spray head 18 are arranged at the upper part in the reaction tower 10 and above the defluorination filling 11 and are used for spraying reaction liquid and sulfuric acid respectively, tail gas generated by the reaction kettle 5 is sent to an air inlet at the lower part of the reaction tower 10 through an exhaust pipe 1 from an air outlet at the top of the reaction kettle, the defluorination reaction liquid is sent to the position above the reaction liquid level in the reaction kettle 5 from a liquid outlet at the bottom of the reaction tower 10, and the tail gas of the reaction tower 10 is discharged from the air outlet at the top of the reaction kettle.
Specifically, the spraying amount of the reaction liquid spraying head 12 in the embodiment of the present invention is 0.5 to 2.0 times that of the sulfuric acid spraying head 18.
The defluorinated filling 11 in the embodiment of the invention is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150 mm.
The absorption tower 17 in the embodiment of the present invention is filled with an absorption filler 16, tail gas discharged from the reaction tower 10 is sent to the absorption tower 17 through a pipeline with a fan 13 and is located below the absorption filler 16, a washing liquid spray head 19 is disposed in the absorption tower 17 and above the absorption filler 16, the washing liquid and gas are in countercurrent contact on the absorption filler 16, and fluosilicic acid is obtained at the bottom of the absorption tower 17.
On the other hand, the embodiment of the invention also provides a defluorination system of the wet-process phosphoric acid, which comprises a reaction kettle 5, an absorption tower 17 and a reaction tower 10; the reaction tower 10 is positioned above the reaction kettle 5, a defluorination filler 11 is arranged in the reaction tower 10, a sulfuric acid spray head 18 and a reaction liquid spray head 12 are arranged in the reaction tower and above the defluorination filler 11, a liquid outlet at the bottom of the reaction tower is communicated with the reaction kettle 5, an air inlet on the reaction tower is positioned below the defluorination filler 11 and is connected with the reaction kettle 5 through an exhaust pipe 1 for receiving tail gas of the reaction kettle 5, and an air outlet at the top of the reaction tower is connected with an air inlet of an absorption tower 17 through a pipeline; the sulfuric acid spray head 18 is connected with the sulfuric acid storage tank 15 through a pipeline for spraying sulfuric acid, and the reaction liquid spray head 12 is connected with the reaction kettle 5 through a pipeline for spraying reaction liquid.
The exhaust port at the top of the reaction kettle 5 is connected with the side wall at the lower part of a reaction tower 10 through an exhaust pipe 1, a stirrer 8 is arranged in the exhaust port, a phosphoric acid discharge port 6 is arranged at the bottom of the exhaust port, and the exhaust port is connected with a reaction liquid spray head 12 through a reaction liquid conveying pipeline 7 with a pump 9.
The absorption tower 17 in the embodiment of the present invention is filled with an absorption filler 16, a washing liquid spray head 19 is disposed at the upper part of the absorption filler 16, an air inlet at the lower part of the absorption filler 16 is connected with an air outlet of the reaction tower 10 through a pipeline with a fan 13, a tail gas outlet is disposed at the top of the absorption tower, and a fluorine recovery liquid outlet 4 is disposed at the bottom of the absorption tower.
The reaction tower 10 in the embodiment of the invention is located right above the reaction kettle 5, a liquid outlet of the reaction tower is led into the reaction kettle 5 through the return pipe 2 and is above the reaction liquid level, and the flow of the return pipe 2 is larger than the sum of the spraying amount of the reaction liquid spray head 12 and the spraying amount of the sulfuric acid spray head 18.
Specifically, the volume of the stripping tower 10 in the embodiment of the invention is 0.5-2.0 times of the volume of the reaction kettle 5, and the height of the filling material in the stripping tower is 3-10m; the defluorination filler 11 is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150 mm.
The technical scheme provided by the embodiment of the invention has the beneficial effects that: the embodiment of the invention provides a defluorination method and a defluorination system for wet-process phosphoric acid; in the production process, if sulfuric acid is directly injected into the bottom of the reaction kettle, the escape of fluorine is almost zero; this is because sulfuric acid is locally reacted and overheated at the bottom of the kettle, and fluoride is dissolved in the reaction liquid during the rising process of the generated steam. If the sulfuric acid is dripped on the liquid level of the reaction kettle, the recovery rate of fluorine can reach 10%; this is due to the fact that the sulfuric acid partially reacts over heat at the liquid level, and the generated vapor rapidly leaves the liquid level, where the fluoride is carried away from the liquid level by the vapor as soon as it is dissolved in the liquid. The reaction liquid and sulfuric acid are mixed and reacted on the surface of the defluorinated filler, so that the surface reaction area is greatly increased, the sulfuric acid reacts with the fluorine-containing reaction liquid to generate heat, the generated fluorine-containing steam hardly contacts with the liquid in the reaction kettle, and meanwhile, the high-temperature steam generated by the reaction kettle and the reaction liquid are in countercurrent contact (the reaction liquid is dispersed and contacts with the rising air flow) on the defluorinated filler, so that the overflow of fluorine is facilitated; the rising air flow rapidly sends fluorine overflowed from the defluorinated filling material and fluorine generated on the surface of the defluorinated filling material due to the local high temperature of sulfuric acid reaction to the absorption tower for recovery, and in addition, the fan can make the system negative pressure, thereby being beneficial to removing fluorine; in a word, the recovery rate of fluorine is greatly improved by the whole process, which can reach more than 18 percent and can be improved by more than 80 percent.
Drawings
Fig. 1 is a schematic structural diagram of a defluorination system for wet-process phosphoric acid according to an embodiment of the present invention.
In the figure: the device comprises an exhaust pipe 1, a return pipe 2, a fluosilicic acid storage tank 3, a fluosilicic acid recovery liquid outlet 4, a reaction kettle 5, a phosphoric acid discharge port 6, a reaction liquid conveying pipeline 7, a stirrer 8, a pump 9, a reaction tower 10, defluorinated filler 11, a reaction liquid spray head 12, a fan 13, a control valve 14, a sulfuric acid storage tank 15, an absorption filler 16, an absorption tower 17, a sulfuric acid spray head 18 and a washing liquid spray head 19.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Example 1
Referring to fig. 1, embodiment 1 provides a defluorination system for wet-process phosphoric acid, which comprises a reaction kettle 5, an absorption tower 17, etc., wherein the reaction kettle 5 is used for reacting sulfuric acid with phosphorite slurry to obtain phosphoric acid, the absorption tower 17 is used for treating tail gas generated by the reaction with water or alkali (preferably water) to obtain fluorine recovery liquid (such as fluosilicic acid), and the structure is basically the same as that of the prior defluorination system for wet-process phosphoric acid, and the difference is that: the defluorination system of the present embodiment further includes a reaction tower 10 for facilitating fluorine recovery. Wherein, reaction tower 10 is located the top of reation kettle 5, it includes conventional tower body structure, it is equipped with defluorination filler 11 in (the middle part), it is interior (upper portion) and be located defluorination filler 11 top and be equipped with sulfuric acid shower nozzle 18 (at least one, set up as required, in order to evenly spray on defluorination filler 11) and reaction liquid shower nozzle 12 (at least one, set up as required, in order to evenly spray on defluorination filler 11), the liquid outlet of its bottom (through back flow 2) communicates with reation kettle 5, it is last (lower part) and be located the air inlet of defluorination filler 11 below and be connected with reation kettle 5 (top) through the blast pipe and be used for receiving reation kettle 5's tail gas, the gas vent at its top is connected with the air inlet of absorption tower 17 (lower part) through the pipeline. The sulfuric acid spray head 18 is connected with the sulfuric acid storage tank 15 through a pipeline (a pump or/and a valve is arranged according to the requirement, the sulfuric acid storage tank 15 is an overhead tank in the embodiment, the overhead tank is arranged above the reaction tower 10, and the sulfuric acid spray head 18 is connected with the pipeline with the control valve 14) for spraying sulfuric acid. The reaction solution spray head 12 is connected with the reaction kettle 5 through a pipeline (a reaction solution conveying pipeline 7) for spraying the reaction solution.
Referring to fig. 1, an exhaust port at the top of a reaction kettle 5 in the embodiment of the present invention is connected to a side wall at the lower part of a reaction tower 10 (which is required to be located above the liquid level in the reaction tower 10) through an exhaust pipe 1, a stirrer 8 is disposed in the reaction kettle, a phosphoric acid discharge port 6 (which is output to a filtering device or a reaction kettle at the next stage (without the reaction tower)) is disposed at the bottom of the reaction kettle, and the phosphoric acid discharge port is connected to a reaction liquid spray head 12 through a reaction liquid conveying pipeline 7 with a pump 9.
Referring to fig. 1, the absorption tower 17 in the embodiment of the present invention is of a conventional structure, in which an absorption filler 16 (a conventional filler for absorbing fluorine, smaller than the defluorinated filler 11) is filled, a washing liquid spray head 19 is disposed at an upper portion of the absorption tower, above the absorption filler 16, an air inlet at a lower portion of the absorption tower and below the absorption filler 16 is connected to an air outlet of the reaction tower 10 through a pipeline with a fan 13 (which simultaneously makes the whole system under negative pressure, and facilitates fluorine removal), a tail gas outlet (evacuation or further treatment) is disposed at a top of the absorption tower, and a fluorine recovery liquid outlet 4 (output to the fluorosilicic acid storage tank 3) is disposed at a bottom of the absorption tower.
Referring to fig. 1, the stripping tower 10 in the embodiment of the present invention is located right above the reaction kettle 5, and the liquid outlet of the stripping tower is led into the reaction kettle 5 through a return pipe 2 (specifically, a vertical straight pipe may be used to pass through the top of the reaction kettle 5 downwards) and is above the reaction liquid level (the reaction of the returned liquid on the surface of the reaction liquid is also beneficial to the overflow of fluorine), so that the flow rate of the return pipe 2 is greater than the sum of the spraying amount of the reaction liquid spray head 12 and the spraying amount of the sulfuric acid spray head 18 to avoid the liquid accumulation at the bottom of the reaction tower 10.
Specifically, the volume of the stripping tower 10 in the embodiment of the invention is 0.5-2.0 times of the volume of the reaction kettle 5, and the height of the filling material in the stripping tower is 3-10m. The defluorination filler 11 is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150mm, so that the risk of blockage can be reduced.
The pipeline between the structures is provided with a fan, a pump, a valve, a flowmeter and the like according to the requirements.
Example 2
Example 2 provides a method for defluorination of wet-process phosphoric acid, employing the defluorination system provided in example 1, comprising: adding phosphorus ore pulp (continuously adding, intermittently adding or adding all at once, preferably adding all at once) into a reaction kettle 5, uniformly spraying sulfuric acid (from a sulfuric acid storage tank 15) and reaction liquid from the reaction kettle 5 on the surface of a defluorinated filler 11 in a reaction tower 10 through a sulfuric acid spray head 18 and a reaction liquid spray head 12 respectively to realize rapid reaction of the reaction liquid and sulfuric acid so as to facilitate fluorine overflow, simultaneously sending tail gas generated by the reaction kettle 5 into the reaction tower 10 to the position below the defluorinated filler 11, carrying out defluorination by countercurrent contact between spray liquid (from the sulfuric acid spray head 18 and the reaction liquid spray head 12) and tail gas (from the reaction kettle 5) on the defluorinated filler 11, and refluxing the defluorinated reaction liquid to the reaction kettle 5 through a reflux pipe 2 to continue the reaction, thereby obtaining defluorinated phosphoric acid from the bottom of the reaction kettle 5 after the reaction is completed. The tail gas from the reaction column 10 (gas generated by the surface reaction of the defluorinated packing 11 and upward in countercurrent on the defluorinated packing 11) is sent to an absorption column 17 to recover fluorine. Wherein, the reaction temperature in the reaction kettle 5 is preferably less than 90 ℃, the proportion of sulfuric acid to the phosphorus ore pulp is consistent with that of the conventional reaction, and the reaction time is preferably longer than that of the conventional reaction.
Further, referring to fig. 1, in the embodiment of the present invention, a reaction liquid spray head 12 and a sulfuric acid spray head 18 are disposed at the upper part of the reaction tower 10 and above the defluorinated packing 11, and are used for spraying the reaction liquid and sulfuric acid respectively, the tail gas generated by the reaction kettle 5 is sent to the air inlet at the lower part (side wall) of the reaction tower 10 through the exhaust pipe 1 at the top of the reaction kettle, the defluorinated reaction liquid is sent to the upper part of the reaction liquid level in the reaction kettle 5 through the liquid outlet at the bottom of the reaction tower 10 (through the return pipe 2), and the tail gas of the reaction tower 10 is discharged to the absorption tower 17 through the air outlet at the top of the reaction tower.
Specifically, the spraying amount of the reaction liquid spraying head 12 in the embodiment of the present invention is 0.5 to 2.0 times that of the sulfuric acid spraying head 18.
The defluorinated filling 11 in the embodiment of the invention is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150mm, so that the risk of blockage can be reduced.
Referring to fig. 1, an absorption tower 17 is filled with an absorption filler 16, tail gas discharged from a reaction tower 10 is sent to the absorption tower 17 through a pipeline with a fan 13 and is located below the absorption filler 16, a washing liquid spray head 19 (input water) is arranged in the absorption tower 17 and above the absorption filler 16, and washing liquid and gas are in countercurrent contact on the absorption filler 16, so that fluosilicic acid is obtained at the bottom of the absorption tower 17. The fluorine recovery rate is calculated to be more than 18 percent.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (6)
1. A method for defluorination of wet process phosphoric acid, the method comprising: adding phosphorus ore pulp into a reaction kettle (5), uniformly spraying sulfuric acid and reaction liquid from the reaction kettle (5) on the surface of a defluorination filler (11) in a reaction tower (10), simultaneously conveying tail gas generated by the reaction kettle (5) into the reaction tower (10) to the position below the defluorination filler (11), carrying out defluorination by countercurrent contact between the spray liquid and the tail gas on the defluorination filler (11), refluxing the defluorination reaction liquid to the reaction kettle (5) for continuous reaction, obtaining defluorination phosphoric acid by the reaction kettle (5), and conveying the tail gas of the reaction tower (10) to an absorption tower (17) for recycling fluorine;
the upper part in the reaction tower (10) and above the defluorination filler (11) is provided with a reaction liquid spray head (12) and a sulfuric acid spray head (18) for spraying reaction liquid and sulfuric acid respectively, tail gas generated by the reaction kettle (5) is sent to an air inlet at the lower part of the reaction tower (10) through an exhaust pipe (1), the defluorination reaction liquid is sent to the upper part of the reaction liquid level in the reaction kettle (5) through a liquid outlet at the bottom of the reaction tower (10), and the tail gas of the reaction tower (10) is discharged through an exhaust outlet at the top of the reaction tower;
the defluorination filler (11) is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150 mm.
2. The method for defluorination of wet process phosphoric acid according to claim 1, wherein the spraying amount of the reaction liquid spray head (12) is 0.5-2.0 times that of the sulfuric acid spray head (18).
3. The defluorination method of wet-process phosphoric acid according to claim 1, wherein the absorption tower (17) is filled with absorption filler (16), the tail gas discharged from the reaction tower (10) is sent into the absorption tower (17) through a pipeline with a fan (13) and is positioned below the absorption filler (16), a washing liquid spray head (19) is arranged in the absorption tower (17) and is positioned above the absorption filler (16), and the washing liquid and the gas are in countercurrent contact on the absorption filler (16), so that fluosilicic acid is obtained at the bottom of the absorption tower (17).
4. A defluorination system of wet-process phosphoric acid comprises a reaction kettle (5) and an absorption tower (17); characterized in that the reactor also comprises a reaction tower (10); the reaction tower (10) is positioned above the reaction kettle (5), a defluorination filler (11) is arranged in the reaction tower, a sulfuric acid spray head (18) and a reaction liquid spray head (12) are arranged above the defluorination filler (11) in the reaction tower, a liquid outlet at the bottom of the reaction tower is communicated with the reaction kettle (5), an air inlet on the reaction tower and below the defluorination filler (11) is connected with the reaction kettle (5) through an exhaust pipe (1) and used for receiving tail gas of the reaction kettle (5), and an air outlet at the top of the reaction tower is connected with an air inlet of the absorption tower (17) through a pipeline; the sulfuric acid spray head (18) is connected with the sulfuric acid storage tank (15) through a pipeline for spraying sulfuric acid, and the reaction liquid spray head (12) is connected with the reaction kettle (5) through a pipeline for spraying reaction liquid;
the absorption tower (17) is internally filled with absorption filler (16), a washing liquid spray head (19) is arranged at the upper part in the absorption tower and above the absorption filler (16), an air inlet at the lower part of the absorption tower and below the absorption filler (16) is connected with an air outlet of the reaction tower (10) through a pipeline with a fan (13), a tail gas outlet is arranged at the top of the absorption tower, and a fluorine recovery liquid outlet (4) is arranged at the bottom of the absorption tower;
the volume of the reaction tower (10) is 0.5-2.0 times of the volume of the reaction kettle (5), and the height of the filler in the reaction tower is 3-10m; the defluorination filler (11) is formed by stacking acid-resistant bricks or plates with the side length of 100-1000mm according to the requirements that the included angle between the acid-resistant bricks or plates and the vertical direction is smaller than 10 degrees and the block spacing or plate spacing is 80-150 mm.
5. The defluorination system for wet-process phosphoric acid according to claim 4, wherein the exhaust port at the top of the reaction kettle (5) is connected with the side wall at the lower part of the reaction tower (10) through an exhaust pipe (1), a stirrer (8) is arranged in the reaction kettle, a phosphoric acid discharge port (6) is arranged at the bottom of the reaction kettle, and the reaction kettle is connected with a reaction liquid spray head (12) through a reaction liquid conveying pipeline (7) with a pump (9).
6. The defluorination system for wet-process phosphoric acid according to claim 4, wherein the reaction tower (10) is located right above the reaction kettle (5), the liquid outlet of the reaction tower is led into the reaction kettle (5) through a return pipe (2) and is above the reaction liquid level, and the flow rate of the return pipe (2) is larger than the sum of the spraying amount of the reaction liquid spray head (12) and the spraying amount of the sulfuric acid spray head (18).
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| CN110980674A (en) * | 2019-12-17 | 2020-04-10 | 黄冈师范学院 | Defluorinated phosphoric acid production process and apparatus |
| CN212356551U (en) * | 2020-07-23 | 2021-01-15 | 湖北祥云(集团)化工股份有限公司 | Defluorination system of wet process phosphoric acid |
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| CN1088181A (en) * | 1993-04-03 | 1994-06-22 | 刘传书 | Tower wet method strong phosphoric acid production method and equipment |
| CN106587073A (en) * | 2016-12-26 | 2017-04-26 | 杨海 | Fluosilicic acid comprehensive recycling technology |
| CN110980674A (en) * | 2019-12-17 | 2020-04-10 | 黄冈师范学院 | Defluorinated phosphoric acid production process and apparatus |
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