CN112194110A - Method for preparing industrial-grade potassium dihydrogen phosphate - Google Patents
Method for preparing industrial-grade potassium dihydrogen phosphate Download PDFInfo
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- CN112194110A CN112194110A CN202011089566.8A CN202011089566A CN112194110A CN 112194110 A CN112194110 A CN 112194110A CN 202011089566 A CN202011089566 A CN 202011089566A CN 112194110 A CN112194110 A CN 112194110A
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- phosphoric acid
- sodium chloride
- dihydrogen phosphate
- 30min
- potassium dihydrogen
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- 229910000402 monopotassium phosphate Inorganic materials 0.000 title claims abstract description 56
- 235000019796 monopotassium phosphate Nutrition 0.000 title claims abstract description 56
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims abstract description 31
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 112
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 84
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 55
- 239000011780 sodium chloride Substances 0.000 claims abstract description 41
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 30
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 26
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 claims abstract description 22
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 claims abstract description 21
- 239000000243 solution Substances 0.000 claims abstract description 20
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 19
- 239000002440 industrial waste Substances 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 239000012452 mother liquor Substances 0.000 claims abstract description 17
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 16
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 15
- 239000001103 potassium chloride Substances 0.000 claims abstract description 13
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 13
- 239000012047 saturated solution Substances 0.000 claims abstract description 13
- 230000032683 aging Effects 0.000 claims abstract description 12
- 239000006227 byproduct Substances 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 239000011265 semifinished product Substances 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000002002 slurry Substances 0.000 claims abstract description 9
- 230000005484 gravity Effects 0.000 claims abstract description 8
- 239000000047 product Substances 0.000 claims abstract description 7
- 238000000926 separation method Methods 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 4
- 238000003756 stirring Methods 0.000 claims description 13
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 11
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 11
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 11
- 239000002994 raw material Substances 0.000 claims description 4
- 238000000605 extraction Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 238000011085 pressure filtration Methods 0.000 claims description 3
- 159000000003 magnesium salts Chemical class 0.000 claims description 2
- 239000012535 impurity Substances 0.000 abstract description 6
- 238000001914 filtration Methods 0.000 abstract description 5
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000002425 crystallisation Methods 0.000 description 5
- 230000008025 crystallization Effects 0.000 description 5
- 239000003337 fertilizer Substances 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 4
- 239000012065 filter cake Substances 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000003472 neutralizing effect Effects 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 description 1
- 229940062672 calcium dihydrogen phosphate Drugs 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 235000019691 monocalcium phosphate Nutrition 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
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Classifications
-
- 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
- C01B25/26—Phosphates
- C01B25/30—Alkali metal phosphates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/04—Chlorides
- C01D3/06—Preparation by working up brines; seawater or spent lyes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Removal Of Specific Substances (AREA)
Abstract
A method for preparing industrial-grade potassium dihydrogen phosphate comprises feeding wet-process phosphoric acid or industrial waste phosphoric acid into a neutralization tank, adding sodium carbonate, reacting at 70-90 deg.C, adjusting pH to 7-9, reacting for 30min, adjusting pH of the solution to 3.5-5.0 with phosphoric acid, press-filtering the reacted neutralized slurry with a filter press, and washing; adding potassium chloride, reacting at 80-90 deg.C for 30min, and controlling specific gravity of the decomposition liquid to 30-40 Be; cooling the reacted decomposition liquid to 20-30 ℃, and performing centrifugal separation to obtain about 95% of monopotassium phosphate semi-finished product; aging with saturated potassium dihydrogen phosphate solution for 30min to increase the content of potassium dihydrogen phosphate product to 98%; centrifuging to separate semi-finished mother liquor, adjusting pH to above 7, concentrating to remove half of water, separating out sodium chloride at 80 deg.C, and aging by-product sodium chloride with 60 deg.C sodium chloride saturated solution for 30min to obtain by-product 99% sodium chloride. The invention uses sodium carbonate to remove impurities in wet-process phosphoric acid or industrial waste phosphoric acid, achieves the aim of purifying phosphoric acid, and reduces the cost of monopotassium phosphate.
Description
Technical Field
The invention relates to a method for preparing industrial-grade potassium dihydrogen phosphate from wet-process phosphoric acid or industrial waste phosphoric acid, which prepares fine phosphate by purification-reaction-purification and belongs to the technical field of fine phosphorus chemical industry.
Background
The potassium dihydrogen phosphate is widely applied to the industries of modern chemical industry, medicine, food, agriculture, feed and the like. Particularly in agriculture, the potassium dihydrogen phosphate is a high-efficiency compound fertilizer containing phosphorus and potassium, and with the rapid development of national high-efficiency agriculture, water-saving agriculture and water-fertilizer integration, the potassium dihydrogen phosphate brings wide market demands for the development of water-soluble fertilizers, liquid fertilizers and industrial-grade potassium dihydrogen phosphate which is a required raw material of the liquid fertilizers.
The potassium dihydrogen phosphate is produced by neutralizing hot phosphoric acid (or purified phosphoric acid) and potassium hydroxide, and comprises the steps of neutralization reaction, crystallization, filtration and drying to obtain a product. Because the price of the thermal phosphoric acid (or purified phosphoric acid) and the potassium hydroxide is high, the production cost of the process is high, and the production factory is only slightly beneficial or not beneficial.
The invention adopts wet-process phosphoric acid or industrial waste phosphoric acid and potassium chloride as raw materials to produce the potassium dihydrogen phosphate, and because the cheap wet-process phosphoric acid or industrial waste phosphoric acid is used for replacing hot-process phosphoric acid (or purified phosphoric acid) and the potassium chloride is used for replacing expensive potassium hydroxide, the product cost is greatly reduced.
Disclosure of Invention
The invention aims to solve the problems of wet-process phosphoric acid purification or comprehensive utilization of industrial waste phosphoric acid, namely changing waste into valuable, introduce potassium chloride into the production of monopotassium phosphate and achieve the aim of reducing the production cost of monopotassium phosphate.
The purpose of the invention is realized by the following technical scheme.
A method for preparing industrial-grade potassium dihydrogen phosphate from wet-process phosphoric acid or industrial waste phosphoric acid comprises mixing wet-process phosphoric acid or industrial waste phosphoric acid (containing P)2O520-25 percent) of the sodium hydroxide solution is fed into a neutralization tank, sodium carbonate is added, the reaction is carried out at the temperature of 70-90 ℃, the pH value is adjusted to 7-9, the reaction is carried out for 30min, the pH value of the solution is adjusted to 3.5-5.0 by phosphoric acid, and the reacted neutralization slurry is subjected to pressure filtration and washing by a filter press to obtain purified sodium dihydrogen phosphate solution; adding potassium chloride, reacting at 80-90 deg.C for 30min, and controlling specific gravity of the decomposition liquid to 30-40 Be; cooling the reacted decomposition liquid to 20-30 ℃, and performing centrifugal separation to obtain about 95% of monopotassium phosphate semi-finished product; at normal temperature, ageing the mixture for 30min by using a monopotassium phosphate saturated solution, and increasing the content of a monopotassium phosphate finished product to 98%; centrifuging to adjust pH to above 7, concentrating to remove half of water, and separating sodium chloride at 80 deg.C, wherein the sodium chloride contains about 0.2-0.5% P2O51.5-2.5% of K2O, aging the byproduct sodium chloride in a saturated solution of sodium chloride at 60 ℃ for 30min to obtain a byproduct of 99%Sodium chloride. After extraction of sodium chloride, the purified mother liquor is sent to a neutralization tank, neutralized with phosphoric acid and sent to the next cycle.
After the harmful impurities such as heavy metal, fluoride, silicate, alkaline earth metal and the like contained in the wet-process phosphoric acid or the industrial waste phosphoric acid are added with sodium carbonate for neutralization, the harmful impurities form insoluble phosphate through the change of pH value and are coprecipitated into a solid phase, and the purified sodium dihydrogen phosphate solution is obtained through filter pressing and separation.
In the purified sodium dihydrogen phosphate solution, the invention adopts n (P)2O5)：n(K2O) ═ 1: 1, adding quantitative potassium chloride according to an equal molar ratio relationship, fully reacting the decomposition liquid for 30min, cooling and crystallizing to obtain a monopotassium phosphate semi-finished product, adding a monopotassium phosphate saturated solution into the monopotassium phosphate semi-finished product, controlling the specific gravity of 45-50Be, stirring at a speed of 25-35 r/min, aging at a temperature of 20-30 ℃ for 30min to obtain fine monopotassium phosphate, and meeting the requirements of industrial monopotassium phosphate.
The mother liquor of the potassium dihydrogen phosphate semi-finished product is centrifugally separated, the pH value is neutralized to Be more than 7 by using sodium carbonate, magnesium salts remained in the mother liquor are removed, 50% of water is concentrated, crude sodium chloride is separated at 80 ℃, the crude sodium chloride is added into a 60 ℃ sodium chloride saturated solution, the specific gravity is controlled to Be 45-50Be, the stirring speed is 25-35 r/min, the temperature is maintained to Be 60 +/-5 ℃, and the aging is carried out for 30min, so that the refined sodium chloride is obtained. (the content of the sodium chloride is more than 99 percent, and the requirement of the small joint alkali industry on the quality of the sodium chloride is met.)
The invention can add the low-cost wet-process phosphoric acid with high impurity content or the industrial waste phosphoric acid into the sodium carbonate for neutralization and deslagging to purify the wet-process phosphoric acid or the industrial waste phosphoric acid, thereby replacing the high-cost hot-process phosphoric acid, easily obtaining the raw materials and changing waste into valuable. The purified sodium dihydrogen phosphate and potassium chloride are subjected to double decomposition reaction, potassium chloride is used for replacing potassium hydroxide in the traditional neutralization method, and industrial-grade potassium dihydrogen phosphate is obtained, so that the production cost of the industrial potassium dihydrogen phosphate is greatly reduced.
The yield of potassium is more than or equal to 90 percent, the yield of water-soluble phosphorus participating in double decomposition reaction is more than or equal to 90 percent, the process is easy to realize, the operation is simple, the cost is low, and the product quality is high; the device is easy to realize and amplify, and the equipment needs to consider the corrosion of chloride ions.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
A method for preparing industrial-grade potassium dihydrogen phosphate from wet-process phosphoric acid or industrial waste phosphoric acid comprises mixing wet-process phosphoric acid or industrial waste phosphoric acid (containing P)2O520-25 percent) of the sodium hydroxide solution is fed into a neutralization tank, sodium carbonate is added, the reaction is carried out at the temperature of 70-90 ℃, the pH value is adjusted to 7-9, the reaction is carried out for 30min, the pH value of the solution is adjusted to 3.5-5.0 by phosphoric acid, and the reacted neutralization slurry is subjected to pressure filtration and washing by a filter press to obtain purified sodium dihydrogen phosphate solution; adding potassium chloride, reacting at 80-90 deg.C for 30min, and controlling specific gravity of the decomposition liquid to 30-40 Be; cooling the reacted decomposition liquid to 20-30 ℃, and performing centrifugal separation to obtain about 95% of monopotassium phosphate semi-finished product; at normal temperature, ageing the mixture for 30min by using a monopotassium phosphate saturated solution, and increasing the content of a monopotassium phosphate finished product to 98%; centrifuging to adjust pH to above 7, concentrating to remove half of water, and separating sodium chloride at 80 deg.C, wherein the sodium chloride contains about 0.2-0.5% P2O51.5-2.5% of K2And O, aging the byproduct sodium chloride in a saturated sodium chloride solution at 60 ℃ for 30min to obtain the byproduct 99% sodium chloride. After extraction of sodium chloride, the purified mother liquor is sent to a neutralization tank, neutralized with phosphoric acid and sent to the next cycle.
The production process comprises the following steps:
1. preparation of industrial grade potassium dihydrogen phosphate from wet-process phosphoric acid
2000kg of a solution containing 20% P2O5The wet-process phosphoric acid is put into a neutralization tank with a heating coil (the heating area is 5-10 m)2) Stirring (rotating speed is 30 r/min), continuously adding solid sodium carbonate under the stirring action, heating to remove carbon dioxide, controlling slurry temperature at 70-90 deg.C, regulating pH value to 7-9, reacting for 30min, regulating pH value to 3.5-5.0 with phosphoric acid, neutralizing to remove about 4000kg phosphoric acid and about 600kg sodium carbonate, and press-filtering to obtain 3470kg of filtrate containing 16% P2O5The purified sodium dihydrogen phosphate solution of (1) has a byproduct of filter cake of 750kg, the filter cake contains 20% of water and contains P2O533% (wet basis).
3470kg purified sodium dihydrogen phosphate solution is added into a reaction tank with a heating coil (heating area 5-10 m)2) And stirring (rotating speed 30 r/min), adding 615kg of 60% K2Heating to dissolve potassium chloride O, maintaining the temperature of the decomposition liquid at 80-90 deg.C, and reacting for 30min to obtain decomposition liquid with a specific weight of 30-40 Be. And (4) pumping the reacted decomposition liquid into a crystallization tank, and cooling for crystallization at a cooling speed of about 10 ℃/h. Cooling to 28 deg.C, and centrifuging to obtain 740kg crude potassium dihydrogen phosphate with potassium dihydrogen phosphate content of 95.1%. Adding 800L potassium dihydrogen phosphate saturated solution into the crude potassium dihydrogen phosphate, and stirring (rotation speed of 30 rpm) for 30min to obtain 705kg refined potassium dihydrogen phosphate with potassium dihydrogen phosphate content of 98.5%.
About 2995kg of mother liquor, about 126kg of sodium carbonate is added, the pH value of the mother liquor is adjusted to be above 7, and impurities are removed by filtration. Heating to concentrate half of the water, and separating sodium chloride at 80 + -5 deg.C to obtain sodium chloride about 325kg, wherein the sodium chloride contains P2O50.34% of K2And O2.36 percent. Adding 300L sodium chloride saturated solution of 60 deg.C into sodium chloride, keeping the temperature at 60 + -5 deg.C, stirring (rotation speed 30 r/min) for 30min to obtain 301kg by-product of 99% sodium chloride; about 1695kg of purified mother liquor.
The purified mother liquor is injected into a neutralization tank to be neutralized and deslagging together with phosphoric acid, and the next circulation is carried out.
2. Preparation of industrial grade potassium dihydrogen phosphate from industrial waste phosphoric acid
The industrial waste phosphoric acid contains 35 percent of P2O515% sulfuric acid; adding 1000kg industrial waste phosphoric acid into a neutralization tank, adding 2000kg water, adding 460kg feed grade calcium dihydrogen phosphate under stirring, reacting at 80 deg.C for 120min, (after desulfurization, the phosphoric acid contains P)2O5About 22%); then, while maintaining the slurry temperature at 70-90 deg.C, sodium carbonate was added to neutralize the slurry and the pH was adjusted to 3.5-5.0, at which time about 425kg of sodium carbonate was removed and the slurry was press-filtered by a filter press to obtain 2700kg of a slurry containing 17.3% P2O5The purified sodium dihydrogen phosphate solution of (1) has a byproduct filter cake of 725kg and a filter cake water content of 34%Containing P2O515.1% (wet basis).
2700kg of purified sodium dihydrogen phosphate solution is injected into a reaction tank with a heating coil (heating area is 5-10 m)2) Stirring (rotation speed 30 r/min), adding 520kg of 60% K2Heating to dissolve potassium chloride O, maintaining the temperature of the decomposition liquid at 80-90 deg.C, and reacting for 30min to obtain decomposition liquid with a specific weight of 30-40 Be. And (4) pumping the reacted decomposition liquid into a crystallization tank, and cooling for crystallization at a cooling speed of about 10 ℃/h. Cooling to 25 deg.C, centrifuging to obtain crude potassium dihydrogen phosphate 685kg, with potassium dihydrogen phosphate content of 93.6%. Adding 800L potassium dihydrogen phosphate saturated solution into the crude potassium dihydrogen phosphate, and stirring (rotation speed of 30 rpm) for 30min to obtain 650kg refined potassium dihydrogen phosphate with potassium dihydrogen phosphate content of 98.1%.
About 2000kg of mother liquor, about 75kg of sodium carbonate was added, the pH of the mother liquor was adjusted to above 7, and impurities were removed by filtration. Heating to concentrate half of the water, and separating sodium chloride at 80 + -5 deg.C to obtain about 285kg of sodium chloride containing P2O50.25% of K2And O2.89 percent. Adding 300L sodium chloride saturated solution of 60 deg.C into sodium chloride, keeping the temperature at 60 + -5 deg.C, stirring (rotation speed of 30 r/min) for 30min to obtain 270kg by-product of 99% sodium chloride; the mother liquor after purification was about 1450 kg.
The purified mother liquor is injected into a reaction tank, neutralized with phosphoric acid and deslagged, and then circulated for the next time.
Claims (3)
1. A method for preparing industrial-grade potassium dihydrogen phosphate is characterized in that wet-process phosphoric acid or industrial waste phosphoric acid is adopted as a raw material; wherein
P content in industrial waste phosphoric acid2O520-25 percent; the preparation method comprises the following steps: feeding wet phosphoric acid or industrial waste phosphoric acid into a neutralization tank, adding sodium carbonate, reacting at 70-90 ℃, adjusting the pH value to 7-9, reacting for 30min, adjusting the pH value of the solution to 3.5-5.0 by using phosphoric acid, and performing pressure filtration and washing on the reacted neutralized slurry by a filter press to obtain a purified sodium dihydrogen phosphate solution; adding potassium chloride, reacting at 80-90 deg.C for 30min, and controlling specific gravity of the decomposition liquid to 30-40 Be; cooling the reacted decomposition liquid to 20-30 ℃, and performing centrifugal separation to obtain about 95 percent of decomposition liquidThe right potassium dihydrogen phosphate semi-finished product; at normal temperature, ageing the mixture for 30min by using a monopotassium phosphate saturated solution, and increasing the content of a monopotassium phosphate finished product to 98%; centrifuging to separate mother liquor of potassium dihydrogen phosphate semi-finished product, adjusting pH to above 7, concentrating to remove half of water, and separating sodium chloride at 80 deg.C, wherein the sodium chloride contains about 0.2-0.5% of P2O51.5-2.5% of K2O, aging the byproduct sodium chloride in a saturated sodium chloride solution at 60 ℃ for 30min to obtain a byproduct of 99% sodium chloride; after extraction of sodium chloride, the purified mother liquor is sent to a neutralization tank, neutralized with phosphoric acid and sent to the next cycle.
2. The method of claim 1, wherein the concentration of n (P) in the purified sodium dihydrogen phosphate solution is determined by2O5)：n(K2O) ═ 1: 1, adding quantitative potassium chloride according to an equal molar ratio relationship, fully reacting the decomposition liquid for 30min, cooling and crystallizing to obtain a monopotassium phosphate semi-finished product, adding a monopotassium phosphate saturated solution into the monopotassium phosphate semi-finished product, controlling the specific gravity of 45-50Be, stirring at the speed of 25-35 r/min, and aging at the temperature of 20-30 ℃ for 30min to obtain fine monopotassium phosphate.
3. The method for preparing industrial-grade potassium dihydrogen phosphate according to claim 1, wherein the mother liquor of the semi-finished product of potassium dihydrogen phosphate is centrifuged and neutralized to pH 7 or above with sodium carbonate, the magnesium salts remained in the mother liquor are removed, 50% of water is concentrated, crude sodium chloride is separated at 80 ℃, the crude sodium chloride is added into a 60 ℃ sodium chloride saturated solution, the specific gravity is controlled to Be 45-50Be, the stirring speed is 25-35 r/min, the temperature is maintained to Be 60 +/-5 ℃, and the aging is carried out for 30min, so as to obtain refined sodium chloride.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116143092A (en) * | 2023-04-23 | 2023-05-23 | 诸城市浩天药业有限公司 | Method for separating potassium chloride and potassium dihydrogen phosphate from potassium dihydrogen phosphate crystallization mother solution in recycling corn soaking water |
| CN116161632A (en) * | 2022-12-20 | 2023-05-26 | 无锡中天固废处置有限公司 | A method for improving the quality of sodium dihydrogen phosphate produced by aluminum-containing phosphoric acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116161632A (en) * | 2022-12-20 | 2023-05-26 | 无锡中天固废处置有限公司 | A method for improving the quality of sodium dihydrogen phosphate produced by aluminum-containing phosphoric acid |
| CN116143092A (en) * | 2023-04-23 | 2023-05-23 | 诸城市浩天药业有限公司 | Method for separating potassium chloride and potassium dihydrogen phosphate from potassium dihydrogen phosphate crystallization mother solution in recycling corn soaking water |
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