CN115155317A - Treatment process for recycling phosphoric acid by using phosphogypsum - Google Patents
Treatment process for recycling phosphoric acid by using phosphogypsum Download PDFInfo
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- CN115155317A CN115155317A CN202210813946.4A CN202210813946A CN115155317A CN 115155317 A CN115155317 A CN 115155317A CN 202210813946 A CN202210813946 A CN 202210813946A CN 115155317 A CN115155317 A CN 115155317A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/58—Multistep processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/422—Electrodialysis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/44—Ion-selective electrodialysis
- B01D61/445—Ion-selective electrodialysis with bipolar membranes; Water splitting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/44—Ion-selective electrodialysis
- B01D61/46—Apparatus therefor
- B01D61/48—Apparatus therefor having one or more compartments filled with ion-exchange material, e.g. electrodeionisation
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- 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
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- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
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Abstract
The invention relates to a treatment process for recycling phosphoric acid by using phosphogypsum. The invention comprises a pretreatment unit, a replacement electrodialysis unit, a sodium salt concentrated solution tank, a chlorine salt concentrated solution tank, a sodium chloride water tank, a fresh water tank, a chelate resin unit, an acid solution tank, an alkali solution tank, a reaction tank and a filter tank, and is structurally characterized in that: the pretreatment device is characterized by further comprising a bipolar membrane electrodialysis unit, the pretreatment unit is connected with the displacement electrodialysis unit, the displacement electrodialysis unit is connected with a sodium salt concentrated solution tank, a chlorine salt concentrated solution tank, a sodium chloride water tank and a fresh water tank respectively, the sodium salt concentrated solution tank is connected with a chelate resin unit, the chelate resin unit is connected with the bipolar membrane electrodialysis unit, the bipolar membrane electrodialysis unit is connected with an acid solution tank and an alkali solution tank respectively, the alkali solution tank and the chlorine salt concentrated solution tank are connected with the reaction tank, the reaction tank is connected with the filter tank, and the filter tank is connected with the sodium chloride water tank.
Description
Technical Field
The invention relates to a treatment process for recycling phosphoric acid by using phosphogypsum.
Background
The phosphogypsum mainly has two kinds of gray black and gray white, the particle diameter is generally 5-50 mu m, and the content of crystal water is 20-25%. Phosphogypsum is a solid waste produced in a wet-process phosphoric acid process, and mainly comprises calcium sulfate dihydrate, but the composition of the phosphogypsum is complex, and besides calcium sulfate, phosphate rock which is not completely decomposed, residual phosphoric acid, fluoride, acid insoluble substances, organic matters and the like also exist.
The yield of the phosphogypsum is huge, and according to the investigation of 2020, the annual yield of the phosphogypsum in China is about 8000 ten thousand tons/year. The amount of the residual phosphogypsum in the cement industry is estimated to be more than 4 hundred million tons, and the emission of the phosphogypsum is 4000 ten thousand tons every year, which is the largest one in gypsum waste residue, and the discharged phosphogypsum residue occupies a large amount of land, forms a residue mountain and seriously pollutes the environment. Because the phosphogypsum contains various impurities such as phosphorus, fluorine, organic matters and the like, the performance of the phosphogypsum is inferior to that of natural gypsum, and the phosphogypsum cannot be directly used as a gypsum building material. The method has the advantages that the influence rule of impurities on the performance of the phosphogypsum is proved, and the influence of the impurities on the performance of the phosphogypsum is eliminated by economic and effective pretreatment, so that the method is one of the key problems of phosphogypsum recycling.
The transition from linear economy to cyclic economy, first, in cyclic economy, phosphogypsum is classified as a by-product of phosphoric acid, rather than as a waste. Therefore, it is not disposed of by piling or discharged. Instead, it remains in the system as a secondary resource or "reusable raw material". Given that a small number of phosphoric acid producers with global impact produce large quantities of phosphogypsum, this is a necessary outcome for local phosphogypsum management strategies. In the last 30 years phosphogypsum hill heaps have often been considered as refuse heaps. Due to policy-driven factors such as zero waste discharge and recycling economy, the aim of 100% utilization of phosphogypsum is to be achieved by Chinese phosphoric acid producers at present.
The existing treatment method for phosphogypsum comprises the following steps: a water washing purification treatment method, a screening treatment technology, a lime neutralization modification method, a flash burning method and the like.
The water washing and purifying treatment of the phosphogypsum mainly adopts warm water washing, the phosphogypsum is placed in a pulping tank for rinsing, then is further leached in a filter, and is mechanically dehydrated under a vacuum state. Various techniques for using phosphogypsum involve the treatment of phosphogypsum by water washing separation and neutralization of free acids. The key points of purification are two: firstly, dihydrate gypsum which has stable performance and the impurity content which meets the requirements of the building material industry is obtained through washing; secondly, the secondary pollution caused in the washing process is solved. The phosphogypsum washing is influenced by a plurality of factors, including water consumption, washing temperature, stirring time and the like.
The screening treatment of the phosphogypsum is based on the principle that impurities such as phosphorus, fluorine, organic matters and the like are not uniformly distributed in the phosphogypsum, and the impurity contents of the phosphogypsum with different granularity are obviously different. The screening process depends on the impurity distribution and the particle composition of the phosphogypsum, and the process is a good choice only when the impurity distribution is seriously uneven and the screening can greatly reduce the impurity content.
The lime neutralization modification method of phosphogypsum belongs to a chemical method, and soluble P in phosphogypsum 2 O 5 The influence on the application performance is obvious, and residual phosphoric acid in the phosphogypsum can be converted into inert substances by a lime neutralization method. The modification of phosphogypsum, as it is known, is substantially carried out for the most part by the addition of alkaline modifying materials (usually lime) and other performance-improving substances. The lime reacts with the soluble P2O5 and F-to generate inert substances, so that the harm of soluble phosphorus and fluorine can be eliminated.
Flash firing method of phosphogypsum by using P 2 O 5 The compound is decomposed into gas at high temperature (200-400 ℃) or partially converted into inert and stable insoluble phosphate compounds, thereby reducing the harm to the product performance to the minimum and leading harmful substances to be decomposed or converted into inert substances at high temperature. A small amount of organic phosphorus is converted into gas at high temperature and discharged, and inorganic phosphorus is combined with calcium at high temperature to form inert calcium pyrophosphate, so that the harm of impurities such as the organic phosphorus, the inorganic phosphorus and the like to the performance of gypsum is eliminated, and the normal dehydration reaction of the calcium sulfate dihydrate is ensured. The whole process flow is smooth and simplified, does not need washing, avoids the problem of water pollution, but is calcinedA small amount of acid harmful gas is generated in the burning process.
Although the method for washing and purifying the phosphogypsum is relatively common, the method has obvious defects, and has the main defects of more influencing factors, large primary investment, large washing water consumption and high energy consumption, a large amount of waste water is generated by washing, and secondary pollution is prevented by treatment.
The screening method for treating the phosphogypsum relatively reduces the content of certain impurities by controlling the particle size range, but has the defect that the method is only used when the content of the impurities is higher in a smaller range, and has limitation.
The method for modifying the phosphogypsum by acid-base neutralization has simple process, can not eliminate the adverse effect of organic matters, and is suitable for the phosphogypsum with low organic matter content.
Although the flash combustion method for treating the phosphogypsum is an effective method for treating the eutectic phosphorus in the phosphogypsum, the eutectic phosphorus is converted into inert pyrophosphate in the high-temperature calcination process, and organic matters are evaporated and removed, but a small amount of acidic harmful gas is generated in the calcination process. The process is only suitable for phosphogypsum with high content of organic matters and eutectic phosphorus, has limitation, and has small treatment capacity, high process energy consumption and high investment.
The utility model discloses a two polar membrane electrodialysis unit is used for making a round trip to use phosphoric acid's processing system with ardealite commonly, two polar membrane electrodialysis unit normal water tank device all directly covers the case lid on the water tank in prior art, after wasing then be difficult to the water tank lid tight if inaccurate to the case lid location, during external impurity will enter into the water tank, influence two polar membrane electrodialysis unit's normal use, hinge the installation on the water tank with one side of case lid, the other end of case lid then need be fixed with the water tank through locking mechanism.
In view of this, the patent document with application number 201610044451.4 discloses a method for leaching rare earth-containing phosphorite with regenerated phosphoric acid to prepare high-quality phosphoric acid and high-quality phosphogypsum, which is different from the prior art processes, especially the filtering mode of the supernatant is different, the supernatant can be filtered and crystallized by sodium chloride, and the sodium chloride is recovered after crystallization; or the filtered water enters a nanofiltration unit, sodium chloride can be directly recovered from nanofiltration produced water, and nanofiltration concentrated water enters mixed salt for crystallization to generate new salt.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a treatment process for recycling phosphoric acid by using phosphogypsum, which has a reasonable structural design. The method solves the problems of large water consumption, high energy consumption, limitation and higher investment cost of the phosphogypsum caused by the traditional treatment method, and simultaneously avoids secondary pollution to the environment in the technical process of phosphogypsum treatment so as to realize the purposes of energy conservation, emission reduction and resource utilization.
The technical scheme adopted by the invention for solving the problems is as follows: the treatment process for recycling phosphoric acid by using phosphogypsum is characterized by comprising the following steps: the treatment process comprises the following steps:
A. the raw water phosphogypsum of the percolate enters a pretreatment unit to remove impurities;
B. the raw leachate phosphogypsum treated by the pretreatment unit enters a replacement electrodialysis unit because of the performance and the structure of the device: the two compounds are subjected to counter ion exchange, and the product is not mixed with raw materials, so that crystallization, precipitation and separation are not needed, and the product can be concentrated simultaneously, so that after each circulating system is electrified and operated for circulation, the sodium salt concentrated solution, the chlorine salt concentrated solution, the sodium chloride and the fresh water of the displacement pairing compound are formed and enter a fresh water tank for recycling, and the purity of the concentrated water can reach more than 99.5 percent;
C. the sodium salt concentrated water enters a chelating resin unit to remove divalent metal ions;
D. after treatment, the solution NR enters a bipolar membrane electrodialysis unit, the solution NR is introduced into a compartment formed by an anion exchange membrane and a cation exchange membrane, and salt cation N is subjected to the action of a direct current electric field + OH produced by water dissociation through cation exchange and bipolar membranes - In the alkaline chamber, to form ROH, a salt anion R - H produced by water dissociation by anion exchange membranes and bipolar membranes + HR is generated by combining in an acid chamber, wherein HR is phosphoric acid and the acid solution is recycled;
E. the alkaline solution generated by the bipolar membrane electrodialysis unit and the chlorine salt concentrated solution generated by the replacement electrodialysis unit enter a reaction box, and hydroxide precipitation sludge generated by reaction is discharged;
F. the supernatant fluid enters a filter tank for filtration treatment,
G. filtering, crystallizing sodium chloride, and recovering sodium chloride;
the above treatment process is realized by the following treatment system,
the treatment system comprises a pretreatment unit, a replacement electrodialysis unit, a sodium salt concentrated solution tank, a chlorine salt concentrated solution tank, a sodium chloride water tank, a fresh water tank, a chelate resin unit, an acid solution tank, an alkali solution tank, a reaction tank and a filter tank, and is characterized in that: the pretreatment device is characterized by further comprising a bipolar membrane electrodialysis unit, the pretreatment unit is connected with the displacement electrodialysis unit, the displacement electrodialysis unit is connected with a sodium salt concentrated solution tank, a chlorine salt concentrated solution tank, a sodium chloride water tank and a fresh water tank respectively, the sodium salt concentrated solution tank is connected with a chelate resin unit, the chelate resin unit is connected with the bipolar membrane electrodialysis unit, the bipolar membrane electrodialysis unit is connected with an acid solution tank and an alkali solution tank respectively, the alkali solution tank and the chlorine salt concentrated solution tank are connected with the reaction tank, the reaction tank is connected with the filter tank, and the filter tank is connected with the sodium chloride water tank.
Further, performing the following treatment process after the step F;
H. after filtration treatment, the water enters a nanofiltration unit, and sodium chloride can be directly recovered from nanofiltration produced water;
I. the nanofiltration concentrated water enters into mixed salt crystallization to generate new salt.
Furthermore, the treatment system also comprises a nanofiltration unit, a nanofiltration concentrated water tank and a nanofiltration water production tank, wherein the filtration tank is connected with the nanofiltration unit, the nanofiltration unit is respectively connected with the nanofiltration concentrated water tank and the nanofiltration water production tank, and the nanofiltration water production tank is connected with a sodium chloride water tank.
Further, the bipolar membrane electrodialysis unit comprises a support, a water tank, a tank cover, a box hinging seat, a tank cover hinging seat and a hinging shaft, wherein the water tank is arranged on the support, the box hinging seat and the tank cover hinging seat are respectively arranged on one side of the water tank and one side of the tank cover, the box hinging seat is hinged with the tank cover hinging seat through the hinging shaft, and the other side of the water tank and the other side of the tank cover are fixed through a locking mechanism.
Further, locking mechanism includes locking seat, locking chamber, leads the slide bar, leads sliding sleeve, reset spring, handle, locking hook, locking plate and locking hole, locking seat sets up on the water tank, the locking chamber sets up on locking seat, it sets up in the locking chamber to lead the slide bar, it all suits on leading the slide bar with reset spring to lead sliding sleeve and reset spring, handle and locking hook all set up on leading the slide bar, reset spring's both ends respectively with water tank and locking hook contact, the locking plate sets up on the case lid, the locking hole sets up on the locking plate. Adopt this mechanism of advancing can be fixed with case lid and water tank locking, need not to set up guide structure, avoid external impurity to enter into the water tank in, influence its normal use.
Further, the locking hook is arranged in the locking hole. When the box cover and the water tank are locked, the locking hook is clamped in the locking hole, the locking handle is pressed when the box cover is opened, and the locking hook is separated from the locking hole, so that the box cover can be opened.
Furthermore, be provided with the spigot surface No. one on the locking hole, be provided with the spigot surface No. two on the locking hook. After the water tank is cleaned, the tank cover can rotate and fall along the hinge shaft by means of the self-gravity of the tank cover when the tank cover is closed.
Further, the first guide surface is in contact with the second guide surface. The locking plate can press the locking hook and the guide sliding sleeve to move along the guide sliding rod when the box cover contacts with the second guide surface in the falling process of the box cover, so that the reset spring is in a compression state, and after the box cover completely covers the water tank, the reset spring pushes the guide sliding sleeve and enables the locking hook to reset to lock the locking plate, and the fixation of the box cover and the water tank is realized.
Further, a handle is arranged on the other side of the box cover. The box cover is opened when the cleaning is convenient.
Compared with the prior art, the invention has the following advantages: on the premise of not increasing the investment cost remarkably, the process of treating the phosphogypsum by adopting the displacement electrodialysis and the bipolar membrane electrodialysis is fit and circular and economical, the phosphogypsum waste residue is changed into valuable, phosphoric acid is recycled from the waste residue, and a byproduct sodium chloride is recycled. The concentration and purification can be efficiently completed only by replacing the electrodialysis unit, so that the concentration of sodium salt and chloride salt is achieved, the acid-base solution is efficiently separated by bipolar membrane electrodialysis, the acid solution is recycled, the alkali solution reacts with the chloride salt solution, and the byproduct sodium chloride is recycled by the two modes.
The whole treatment process has no loss of medicament, namely the added sodium chloride is recycled and added as a process byproduct, the automation of the whole process is realized, the phosphoric acid is recycled, no pollutant is generated, and the method conforms to the environmental treatment regulations. The treatment process taking the replacement electrodialysis and the bipolar membrane electrodialysis as the core not only reduces the occupied area of equipment in a process unit, but also reduces the labor cost due to automation, is simpler and more convenient to operate, and solves the problems of large water consumption, high energy consumption, limitation and higher investment cost.
The electrodialysis adopts a displacement electrodialysis unit and a bipolar membrane electrodialysis unit and is mainly divided into two process sections. The displacement electrodialysis unit is used for synthesizing a sodium salt concentrated solution and a chlorine salt concentrated solution, and the bipolar membrane electrodialysis unit is used for recovering phosphoric acid. The front end of the displacement electrodialysis unit is provided with a pretreatment unit, and the bipolar membrane electrodialysis is arranged behind the displacement electrodialysis process section to treat the sodium salt concentrated water so as to recover acid. The method for treating the chlorine salt concentrated water has two modes, sodium chloride can be recovered by nanofiltration of fresh water, mixed salt crystallization of the nanofiltration concentrated water can be performed, supernatant can be directly filtered, and the sodium chloride can be recovered after crystallization.
After the water tank is cleaned, the water tank can be tightly covered after the tank cover is put down by installing the locking mechanism, the water tank can be tightly covered without arranging a guide structure, meanwhile, the fixed connection between the tank cover and the water tank can also be realized, and the phenomenon that external impurities enter the water tank to influence the normal use of the bipolar membrane electrodialysis unit is avoided.
Drawings
Fig. 1 is a schematic diagram of a connection relationship of a processing system according to embodiment 1 of the present invention.
Fig. 2 is a schematic diagram of a connection relationship of a processing system according to embodiment 2 of the present invention.
Fig. 3 is a schematic perspective view of a bipolar membrane electrodialysis unit according to an embodiment of the present invention.
Fig. 4 is a schematic perspective view of a bipolar membrane electrodialysis unit according to an embodiment of the present invention.
Fig. 5 is a schematic front view of a bipolar membrane electrodialysis unit according to an embodiment of the present invention.
Fig. 6 isbase:Sub>A schematic view of the cross-sectional structurebase:Sub>A-base:Sub>A in fig. 5.
Fig. 7 is an enlarged view of the portion B in fig. 6.
Fig. 8 is an enlarged structural view of a portion C in fig. 6.
In the figure: a pretreatment unit 1, a replacement electrodialysis unit 2, a sodium salt concentrated solution tank 3, a chlorine salt concentrated solution tank 4, a sodium chloride water tank 5, a fresh water tank 6, a chelating resin unit 7 a bipolar membrane electrodialysis unit 8, an acid solution tank 9, an alkali solution tank 10, a reaction tank 11, a filter tank 12, a nanofiltration unit 13, a nanofiltration concentrated water tank 14, a nanofiltration water production tank 15,
The locking device comprises a support 81, a water tank 82, a tank cover 83, a tank body hinge seat 84, a tank cover hinge seat 85, a hinge shaft 86, a locking seat 87, a locking cavity 88, a guide sliding rod 89, a guide sliding sleeve 810, a return spring 811, a handle 812, a locking hook 813, a locking plate 814, a locking hole 815, a first guide surface 816, a second guide surface 817 and a handle 818.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, in the present specification, if there are words such as "upper", "lower", "left", "right", "middle", and "one", they are used for clarity of description only, and are not intended to limit the scope of the present invention, and changes or modifications in their relative relationship may be made without substantial technical changes.
Example 1 (as shown in figures 1, 3-8).
The treatment process for recycling phosphoric acid from phosphogypsum in the embodiment comprises a pretreatment unit 1, a replacement electrodialysis unit 2, a sodium salt concentrated solution tank 3, a chlorine salt concentrated solution tank 4, a sodium chloride water tank 5, a fresh water tank 6, a chelating resin unit 7, a bipolar membrane electrodialysis unit 8, an acid solution tank 9, an alkali solution tank 10, a reaction tank 11 and a filter tank 12.
In the embodiment, a pretreatment unit 1 is connected with a displacement electrodialysis unit 2, the displacement electrodialysis unit 2 is respectively connected with a sodium salt concentrated solution tank 3, a chlorine salt concentrated solution tank 4, a sodium chloride water tank 5 and a fresh water tank 6, the sodium salt concentrated solution tank 3 is connected with a chelate resin unit 7, the chelate resin unit 7 is connected with a bipolar membrane electrodialysis unit 8, the bipolar membrane electrodialysis unit 8 is respectively connected with an acid solution tank 9 and an alkali solution tank 10, the alkali solution tank 10 and the chlorine salt concentrated solution tank 4 are both connected with a reaction tank 11, the reaction tank 11 is connected with a filter tank 12, and the filter tank 12 is connected with the sodium chloride water tank 5;
the bipolar membrane electrodialysis unit 8 in the present embodiment includes a support 81, a water tank 82, a tank cover 83, a tank hinge seat 84, a tank cover hinge seat 85, and a hinge shaft 86, wherein the water tank 82 is disposed on the support 81, the tank hinge seat 84 and the tank cover hinge seat 85 are respectively disposed on one side of the water tank 82 and the tank cover 83, the tank hinge seat 84 is hinged to the tank cover hinge seat 85 through the hinge shaft 86, and the other side of the water tank 82 and the tank cover 83 is fixed through a locking mechanism.
The locking mechanism in this embodiment comprises a locking seat 87, a locking cavity 88, a sliding guide rod 89, a sliding guide sleeve 810, a return spring 811, a handle 812, a locking hook 813, a locking plate 814 and a locking hole 815, wherein the locking seat 87 is arranged on the water tank 82.
In this embodiment, the locking cavity 88 is disposed on the locking seat 87, the sliding guide rod 89 is disposed in the locking cavity 88, the sliding guide sleeve 810 and the return spring 811 are both sleeved on the sliding guide rod 89, the handle 812 and the locking hook 813 are both disposed on the sliding guide sleeve 810, both ends of the return spring 811 are respectively in contact with the water tank 82 and the locking hook 813, the locking plate 814 is disposed on the case cover 83, the locking hole 815 is disposed on the locking plate 814, the locking hook 813 is disposed in the locking hole 815, the locking hole 815 is provided with the first guiding surface 816, the locking hook 813 is provided with the second guiding surface 817, the first guiding surface 816 is in contact with the second guiding surface 817, and the other side of the case cover 83 is provided with the handle 818.
The treatment process of the present example using phosphogypsum to recycle phosphoric acid comprises the following steps:
A. raw water phosphogypsum of leachate enters a pretreatment unit 1 to remove impurities;
B. leachate raw water phosphogypsum (main component Ca) treated by the pretreatment unit 1 3 (PO 4 ) 2 ) After entering the replacement electrodialysis unit 2, the fresh water tank 6 is filled with sodium chloride (NaCl) solution with a concentration of about 15% in the sodium chloride water tank 5, because of the performance and structure of the device: the compound (Ca) is generated in the interior of the displacement electrodialysis of the two substances 3 (PO 4 ) 2 With NaCl) by counter-ion exchange, i.e. Ca 2+ And PO 4 3- Ion dissociation of original Ca 3 (PO 4 ) 2 The solution, na + and Cl-are separated from the original sodium chloride solution, then Ca 2+ Recombined with Cl-in a new solution, PO 4 3- Combined with Na + in a new solution, so that simultaneous concentration and separation of the product can be achieved, and thus sodium phosphate (Na) is formed in the sodium salt pus tank 3 after the circulation system is powered on for operation cycles 3 PO 4 ) Concentrate, calcium chloride salt (CaCl) formed in the chloride concentrate tank 4 2 ) Ca in the thick liquid and fresh water tank 6 3 (PO 4 ) 2 The concentration is reduced due to the separation of ions, and the concentration of sodium chloride in the sodium chloride water tank 5 is reduced due to the separation of anions and cations, namely, ca is utilized 3 (PO 4 ) 2 Na is generated by replacement electrodialysis with NaCl as raw material 3 PO 4 With CaCl 2 Two new substances, ca in the fresh water tank 6 3 (PO 4 ) 2 The fresh water with the concentration reduced to below 0.1 percent can be recycled, and Na is added 3 PO 4 With CaCl 2 The concentration of the concentrated water can reach more than 15 percent, and the purity can reach more than 99.5 percent;
C. sodium salt (Na) 3 PO 4 Mainly) the concentrated water enters a chelate resin unit 7 to remove divalent metal ions (mainly Ca2+, and the like) and Na can be removed 3 PO 4 The purity is improved from 99.5 percent to over 99.9 percent;
D. high purity Na after treatment 3 PO 4 The salt solution enters a bipolar membrane electrodialysis unit 8 and is high in purity Na 3 PO 4 The salt solution is introduced into a compartment formed by an anion exchange membrane and a cation exchange membrane, and under the action of a direct current electric field, salt cations Na + OH produced by water dissociation by cation exchange and bipolar membranes - In the alkaline chamber, naOH is generated and salt anion PO is generated 4 3- H produced by water dissociation through anion exchange membranes and bipolar membranes + Binding in acid Chamber to generate H 3 PO 4 (phosphoric acid), the high-purity phosphoric acid solution can be recycled or packaged for sale;
E. an alkaline solution (NaOH) generated by the bipolar membrane electrodialysis unit 8 and a chlorine salt (CaCl) generated by the replacement electrodialysis unit 2 2 ) The concentrated solution enters a reaction box 11, and hydroxide (Ca (OH) generated by reaction is generated 2 ) Discharging the precipitated sludge, and then forming a sodium chloride (NaCl) solution in the supernatant;
F. the supernatant enters a filter box 12 for filtering treatment;
G. after the filtration treatment, sodium chloride is crystallized, and after the crystallization, sodium chloride is recovered and can be used in the solution configuration in the sodium chloride water tank 5.
When the water tank 82 is cleaned, the handle 812 is pressed to enable the guide sleeve 810 to move along the guide sliding rod 89, the return spring 811 is in a compressed state, the locking hook 813 is separated from the locking hole 815, and the handle 818 is pulled to enable the tank cover 83 to rotate on the water tank 82 along the hinge shaft 86, so that the tank cover 83 can be opened to facilitate cleaning of the water tank 82; after the water tank 82 is cleaned, the tank cover 83 is rotated and the tank cover 83 can be rotated and dropped along the hinge shaft 86 by the self-gravity of the tank cover 83, when the first guide surface 816 is in contact with the second guide surface 817, the locking plate 814 can press the locking hook 813, and the sliding guide sleeve 810 can move along the sliding guide rod 89, so that the return spring 811 is in a compressed state, and when the tank cover 83 completely covers the water tank 82, the return spring 811 pushes the sliding guide sleeve 810 and resets the locking hook 813 to lock the locking plate 814, so that the tank cover 83 and the water tank 82 are fixed.
Example 2 (as shown in figures 2-8).
The treatment process for recycling phosphoric acid from phosphogypsum comprises a pretreatment unit 1, a replacement electrodialysis unit 2, a sodium salt concentrated solution tank 3, a chlorine salt concentrated solution tank 4, a sodium chloride water tank 5, a fresh water tank 6, a chelating resin unit 7, a bipolar membrane electrodialysis unit 8, an acid solution tank 9, an alkali solution tank 10, a reaction tank 11, a filter tank 12, a nanofiltration unit 13, a nanofiltration concentrated water tank 14 and a nanofiltration water production tank 15.
In the embodiment, a pretreatment unit 1 is connected with a displacement electrodialysis unit 2, the displacement electrodialysis unit 2 is respectively connected with a sodium salt concentrated solution tank 3, a chlorine salt concentrated solution tank 4, a sodium chloride water tank 5 and a fresh water tank 6, the sodium salt concentrated solution tank 3 is connected with a chelate resin unit 7, the chelate resin unit 7 is connected with a bipolar membrane electrodialysis unit 8, the bipolar membrane electrodialysis unit 8 is respectively connected with an acid solution tank 9 and an alkali solution tank 10, the alkali solution tank 10 and the chlorine salt concentrated solution tank 4 are both connected with a reaction tank 11, the reaction tank 11 is connected with a filter tank 12, and the filter tank 12 is connected with the sodium chloride water tank 5; the filter tank 12 is connected with a nanofiltration unit 13, the nanofiltration unit 13 is respectively connected with a nanofiltration concentrated water tank 14 and a nanofiltration water tank 15, and the nanofiltration water tank 15 is connected with the sodium chloride water tank 5.
The bipolar membrane electrodialysis unit 8 in the embodiment comprises a support 81, a water tank 82, a tank cover 83, a tank body hinge seat 84, a tank cover hinge seat 85 and a hinge shaft 86, wherein the water tank 82 is arranged on the support 81, the tank body hinge seat 84 and the tank cover hinge seat 85 are respectively arranged on one side of the water tank 82 and the tank cover 83, the tank body hinge seat 84 is hinged to the tank cover hinge seat 85 through the hinge shaft 86, and the other side of the water tank 82 and the tank cover 83 is fixed through a locking mechanism.
The locking mechanism in this embodiment comprises a locking seat 87, a locking cavity 88, a sliding guide rod 89, a sliding guide sleeve 810, a return spring 811, a handle 812, a locking hook 813, a locking plate 814 and a locking hole 815, wherein the locking seat 87 is arranged on the water tank 82.
In this embodiment, the locking cavity 88 is disposed on the locking seat 87, the sliding guide rod 89 is disposed in the locking cavity 88, the sliding guide sleeve 810 and the return spring 811 are both sleeved on the sliding guide rod 89, the handle 812 and the locking hook 813 are both disposed on the sliding guide sleeve 810, both ends of the return spring 811 are respectively in contact with the water tank 82 and the locking hook 813, the locking plate 814 is disposed on the tank cover 83, the locking hole 815 is disposed on the locking plate 814, the locking hook 813 is disposed in the locking hole 815, the locking hole 815 is provided with the first guide surface 816, the locking hook 813 is provided with the second guide surface 817, the first guide surface 816 is in contact with the second guide surface 817, and the other side of the tank cover 83 is provided with the handle 818.
The treatment process of the phosphorus acid by using the phosphogypsum comprises the following steps:
A. raw water phosphogypsum of leachate enters a pretreatment unit 1 to remove impurities;
B. leachate raw water phosphogypsum (main component Ca) treated by the pretreatment unit 1 3 (PO 4 ) 2 ) After entering the replacement electrodialysis unit 2, the fresh water tank 6 is filled with sodium chloride (NaCl) solution with a concentration of about 15% in the sodium chloride water tank 5, because of the performance and structure of the device: the compound (Ca) is generated in the two substances in the interior of the replacement electrodialysis 3 (PO 4 ) 2 With NaCl) is counter-ion exchanged, i.e. Ca 2+ And PO 4 3- Ion dissociation of original Ca 3 (PO 4 ) 2 The solution, na + and Cl-are separated from the original sodium chloride solution, then Ca 2+ Reconstituted with Cl-in a new solution, PO 4 3- Combined with Na + in a new solution, so that simultaneous concentration and separation of the product can be achieved, and thus sodium phosphate (Na) is formed in the sodium salt pus tank 3 after the circulation system is powered on for operation cycles 3 PO 4 ) Concentrate, calcium chloride salt (CaCl) formed in the chloride concentrate tank 4 2 ) Ca in the thick liquid and fresh water tank 6 3 (PO 4 ) 2 The concentration is reduced due to the separation of ions, and the concentration of sodium chloride in the sodium chloride water tank 5 is reduced due to the separation of anions and cations, namely, ca is utilized 3 (PO 4 ) 2 Na is generated by replacement electrodialysis with NaCl as raw material 3 PO 4 With CaCl 2 Two new substances, ca in the fresh water tank 6 3 (PO 4 ) 2 The concentration is reduced to 0.1 percent toThe fresh water can be reused and reused, and Na is added 3 PO 4 With CaCl 2 The concentration of the concentrated water can reach more than 15 percent, and the purity can reach more than 99.5 percent;
C. sodium salt (Na) 3 PO 4 Mainly) the concentrated water enters the chelate resin unit 7 to remove divalent metal ions (mainly Ca2+, and the like) and can remove Na 3 PO 4 The purity is improved from 99.5 percent to over 99.9 percent;
D. high purity Na after treatment 3 PO 4 The salt solution enters a bipolar membrane electrodialysis unit 8 and is high in purity Na 3 PO 4 The salt solution is introduced into a compartment formed by an anion exchange membrane and a cation exchange membrane, and under the action of a direct current electric field, salt cations Na + OH produced by water dissociation through cation exchange and bipolar membranes - In the alkaline chamber, naOH is generated and salt anion PO is generated 4 3- H produced by water dissociation by anion exchange membranes and bipolar membranes + Binding in acid Chamber to generate H 3 PO 4 (phosphoric acid), the high-purity phosphoric acid solution can be recycled or packaged for sale;
E. an alkaline solution (NaOH) generated by the bipolar membrane electrodialysis unit 8 and a chlorine salt (CaCl) generated by the replacement electrodialysis unit 2 2 ) The concentrated solution enters a reaction box 11, and hydroxide (Ca (OH) generated by reaction is generated 2 ) Discharging the precipitated sludge, and then forming a sodium chloride (NaCl) solution in the supernatant;
F. the supernatant enters a filter box 12 for filtering treatment;
H. after filtration treatment, the water enters a nanofiltration unit 13, and sodium chloride can be directly recovered from nanofiltration produced water;
I. the nanofiltration concentrated water enters into miscellaneous salt for crystallization to generate new salt.
When the water tank 82 is cleaned, the handle 812 is pressed to enable the guide sleeve 810 to move along the guide sliding rod 89, the return spring 811 is in a compressed state, the locking hook 813 is separated from the locking hole 815, and the handle 818 is pulled to enable the tank cover 83 to rotate on the water tank 82 along the hinge shaft 86, so that the tank cover 83 can be opened to facilitate cleaning of the water tank 82; after the water tank 82 is cleaned, the tank cover 83 is rotated and the tank cover 83 can be rotated and dropped along the hinge shaft 86 by the self-gravity of the tank cover 83, when the first guide surface 816 is in contact with the second guide surface 817, the locking plate 814 can press the locking hook 813, and the sliding guide sleeve 810 can move along the sliding guide rod 89, so that the return spring 811 is in a compressed state, and when the tank cover 83 completely covers the water tank 82, the return spring 811 pushes the sliding guide sleeve 810 and resets the locking hook 813 to lock the locking plate 814, so that the tank cover 83 and the water tank 82 are fixed.
In addition, it should be noted that the specific embodiments described in the present specification may be different in the components, the shapes of the components, the names of the components, and the like, and the above description is only an illustration of the structure of the present invention. Equivalent or simple variations of the structures, features and principles described in the present patent application are included in the scope of the present patent. Various modifications, additions and substitutions for the specific embodiments described may occur to those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (9)
1. A treatment process for recycling phosphoric acid by using phosphogypsum is characterized in that: the treatment process comprises the following steps:
A. leachate raw water phosphogypsum enters a pretreatment unit (1) to remove impurities;
B. the leachate raw water phosphogypsum treated by the pretreatment unit (1) enters a displacement electrodialysis unit (2), and because raw materials are not mixed in a product, crystallization, precipitation and separation are not needed, and simultaneous concentration of the product can be realized, so that fresh water of a sodium salt concentrated solution, a chlorine salt concentrated solution, sodium chloride and a displacement pairing compound is formed after each circulation system is electrified and started to operate for circulation and then enters a fresh water tank (6) for recycling, and the purity of the concentrated water can be calculated to be more than 99.5%;
C. sodium salt concentrated water enters a chelating resin unit (7) to remove divalent metal ions;
D. after treatment, the solution is passed into a bipolar membrane electrodialysis unit (8) and the solution NR is passed into a compartment formed by an anion exchange membrane and a cation exchange membraneUnder the action of DC electric field, salt cation N + OH produced by water dissociation through cation exchange and bipolar membranes - In the alkaline chamber, to form ROH, a salt anion R - H produced by water dissociation through anion exchange membranes and bipolar membranes + HR is generated by combining in an acid chamber, wherein HR is phosphoric acid and the acid solution is recycled;
E. the alkaline solution generated by the bipolar membrane electrodialysis unit (8) and the chlorine salt concentrated solution generated by the replacement electrodialysis unit (2) enter a reaction box (11), and the hydroxide precipitation sludge generated by the reaction is discharged;
F. the supernatant enters a filter box (12) for filtering treatment;
G. filtering, crystallizing sodium chloride, and recovering sodium chloride;
the above treatment process is realized by the following treatment system,
the treatment system comprises a pretreatment unit (1), a replacement electrodialysis unit (2), a sodium salt concentrated solution tank (3), a chlorine salt concentrated solution tank (4), a sodium chloride water tank (5), a fresh water tank (6), a chelate resin unit (7), an acid solution tank (9), an alkali solution tank (10), a reaction tank (11) and a filter tank (12), and is characterized in that: still include bipolar membrane electrodialysis unit (8), pretreatment unit (1) is connected with replacement electrodialysis unit (2), replacement electrodialysis unit (2) is connected with sodium salt concentrate case (3), chlorine salt concentrate case (4), sodium chloride water tank (5) and fresh water tank (6) respectively, sodium salt concentrate case (3) is connected with chelate resin unit (7), chelate resin unit (7) is connected with bipolar membrane electrodialysis unit (8), bipolar membrane electrodialysis unit (8) are connected with acid solution case (9) and alkali solution case (10) respectively, alkali solution case (10) and chlorine salt concentrate case (4) all are connected with reaction box (11), reaction box (11) are connected with rose box (12), rose box (12) are connected with sodium chloride water tank (5).
2. The process for recycling phosphoric acid with phosphogypsum according to claim 1, characterized in that: the following treatment process is carried out after step F,
H. after filtration treatment, the water enters a nanofiltration unit (13), and sodium chloride can be directly recovered from nanofiltration produced water;
I. the nanofiltration concentrated water enters into mixed salt crystallization to generate new salt.
3. The process of claim 1, wherein the phosphogypsum is used as a recycling agent for phosphoric acid, and the process comprises the following steps: the treatment system further comprises a nanofiltration unit (13), a nanofiltration concentrated water tank (14) and a nanofiltration water production tank (15), wherein the filtration tank (12) is connected with the nanofiltration unit (13), the nanofiltration unit (13) is respectively connected with the nanofiltration concentrated water tank (14) and the nanofiltration water production tank (15), and the nanofiltration water production tank (15) is connected with the sodium chloride water tank (5).
4. The process for recycling phosphoric acid with phosphogypsum according to claim 1, characterized in that: the bipolar membrane electrodialysis unit (8) comprises a support (81), a water tank (82), a tank cover (83), a tank hinging seat (84), a tank cover hinging seat (85) and a hinging shaft (86), wherein the water tank (82) is arranged on the support (81), the tank hinging seat (84) and the tank cover hinging seat (85) are respectively arranged on one side of the water tank (82) and one side of the tank cover (83), the tank hinging seat (84) is hinged with the tank cover hinging seat (85) through the hinging shaft (86), and the other side of the water tank (82) and the other side of the tank cover (83) are fixed through a locking mechanism.
5. The process of claim 4, wherein the phosphogypsum is recycled by the treatment method, which is characterized in that: locking mechanism includes locking seat (87), locking chamber (88), leads slide bar (89), leads slide sleeve (810), reset spring (811), handle (812), locking hook (813), locking plate (814) and locking hole (815), locking seat (87) set up on water tank (82), locking chamber (88) set up on locking seat (87), it sets up in locking chamber (88) to lead slide bar (89), it all suits on leading slide bar (89) to lead slide sleeve (810) and reset spring (811), handle (812) and locking hook (813) all set up on leading slide sleeve (810), reset spring (811)'s both ends respectively with water tank (82) and locking hook (813) contact, locking plate (814) set up on case lid (83), locking hole (815) set up on locking plate (814).
6. The process of treatment with phosphogypsum with phosphoric acid to-and-fro according to claim 5, characterized in that: the locking hook (813) is arranged in the locking hole (815).
7. The process of treatment with phosphogypsum with phosphoric acid to-and-fro according to claim 5, characterized in that: a first guide surface (816) is arranged on the locking hole (815), and a second guide surface (817) is arranged on the locking hook (813).
8. The process of treatment with phosphogypsum with phosphoric acid to-and-fro according to claim 7, characterized in that: the first guide surface (816) is in contact with the second guide surface (817).
9. The process of treatment with phosphogypsum with phosphoric acid to-and-fro according to claim 5, characterized in that: the other side of the box cover (83) is provided with a handle (818).
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| CN202210813946.4A CN115155317A (en) | 2022-07-12 | 2022-07-12 | Treatment process for recycling phosphoric acid by using phosphogypsum |
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| CN202210813946.4A CN115155317A (en) | 2022-07-12 | 2022-07-12 | Treatment process for recycling phosphoric acid by using phosphogypsum |
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| CN113336356A (en) * | 2021-05-08 | 2021-09-03 | 武汉工程大学 | Phosphogypsum leachate recycling treatment and utilization method |
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|---|---|---|---|---|
| EP3093269A1 (en) * | 2015-05-11 | 2016-11-16 | Technische Universitat Bergakademie Freiberg | Electrodialytic preparation of phosphoric acid and device |
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