CN115724453A - Method for purifying and recovering iron phosphate mother liquor - Google Patents
Method for purifying and recovering iron phosphate mother liquor Download PDFInfo
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- CN115724453A CN115724453A CN202211591678.2A CN202211591678A CN115724453A CN 115724453 A CN115724453 A CN 115724453A CN 202211591678 A CN202211591678 A CN 202211591678A CN 115724453 A CN115724453 A CN 115724453A
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- 239000012452 mother liquor Substances 0.000 title claims abstract description 70
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 37
- 229910000398 iron phosphate Inorganic materials 0.000 title claims abstract description 35
- 238000006243 chemical reaction Methods 0.000 claims abstract description 68
- 239000000706 filtrate Substances 0.000 claims abstract description 36
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000011575 calcium Substances 0.000 claims abstract description 33
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 26
- 239000010440 gypsum Substances 0.000 claims abstract description 26
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 26
- 239000000047 product Substances 0.000 claims abstract description 26
- 238000001914 filtration Methods 0.000 claims abstract description 21
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 13
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 13
- 239000011734 sodium Substances 0.000 claims abstract description 13
- 239000002002 slurry Substances 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 10
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 claims abstract description 9
- 238000002425 crystallisation Methods 0.000 claims abstract description 9
- 230000008025 crystallization Effects 0.000 claims abstract description 9
- 235000019700 dicalcium phosphate Nutrition 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 238000000926 separation method Methods 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 6
- 239000010452 phosphate Substances 0.000 claims abstract description 6
- 230000009466 transformation Effects 0.000 claims abstract description 6
- 239000003513 alkali Substances 0.000 claims abstract description 4
- 238000004537 pulping Methods 0.000 claims abstract description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 22
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 11
- 239000005955 Ferric phosphate Substances 0.000 claims description 10
- 229940032958 ferric phosphate Drugs 0.000 claims description 10
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 10
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 6
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 4
- 238000004064 recycling Methods 0.000 claims description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 abstract description 12
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 abstract description 12
- 239000006012 monoammonium phosphate Substances 0.000 abstract description 12
- 235000019837 monoammonium phosphate Nutrition 0.000 abstract description 12
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 9
- 239000011574 phosphorus Substances 0.000 abstract description 9
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 abstract description 7
- 229910000403 monosodium phosphate Inorganic materials 0.000 abstract description 7
- 235000019799 monosodium phosphate Nutrition 0.000 abstract description 7
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 abstract description 7
- 239000001488 sodium phosphate Substances 0.000 abstract description 7
- 239000002245 particle Substances 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 229910001868 water Inorganic materials 0.000 abstract description 6
- 125000004122 cyclic group Chemical group 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 11
- 239000000243 solution Substances 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 5
- 238000000746 purification Methods 0.000 description 5
- 239000002351 wastewater Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 2
- 235000011130 ammonium sulphate Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000011276 addition treatment Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Abstract
The invention belongs to the field of phosphate preparation, and provides a method for purifying and recovering iron phosphate mother liquor, which comprises the following steps: s1, pulping: mixing the iron phosphate mother liquor and calcium hydrophosphate to prepare slurry; s2, transformation and separation: slowly adding a sulfuric acid solution into the slurry obtained in the step S1 for reaction, and filtering after the reaction is finished to obtain gypsum and a filtrate 1; s3, secondary transformation and separation: slowly adding calcium hydrogen phosphate into the filtrate 1 obtained in the step S2 for reaction, and filtering after the reaction is finished to obtain filter residue and filtrate 2; s4, impurity separation: adding alkali liquor into the filtrate 2 obtained in the step S3 to adjust the pH value, controlling the reaction pH value to be 4.5-6, and filtering after the reaction is finished to obtain filter residue and purified mother liquor; the purified mother liquor obtained by the method can be directly reused in the iron phosphate production process, high-purity monoammonium phosphate or monosodium phosphate products can be obtained through one-time crystallization, and gypsum products with small particle size and good dispersibility can be obtained, so that the cyclic utilization of ammonium/sodium, phosphorus and water resources is realized.
Description
Technical Field
The invention relates to the technical field of mother liquor purification and recovery, in particular to a method for purifying and recovering iron phosphate mother liquor.
Background
The ammonium method/sodium method is a mainstream process for producing iron phosphate at present, the cost of raw materials of the process is low, but the synthetic mother liquor and washing water in the preparation process are high-salt inorganic wastewater containing a large amount of sodium ions/ammonium radicals, sulfate radicals and phosphate radicals and a small amount of phosphorus, iron, manganese, magnesium, calcium, fluorine and the like, if the wastewater is directly discharged, the discharge standard of industrial wastewater is not met, and serious pollution and damage are caused to the surrounding environment.
And it is very important how to change waste water into valuable and reduce the harm of waste water. At present, the mother liquor is concentrated, cooled and crystallized to obtain crude ammonium sulfate/sodium in industry. The process consumes a large amount of heat and produces a large amount of ammonium sulfate/sodium impurities, which is of low value. While ammonium and phosphate radicals can be used as raw materials for producing iron phosphate, but the mother liquor is difficult to recycle due to the existence of other impurities. Therefore, a mother liquor purification and recycling process needs to be developed, so that the mother liquor can be reused for producing iron phosphate, and the recycling of ammonium/sodium, phosphorus and water resources is realized.
Disclosure of Invention
The first purpose of the invention is to provide a method for purifying and recovering iron phosphate mother liquor, which can purify and recover SO in the iron phosphate mother liquor 4 2- 、Fe 3+ 、Al 3+ 、Mg 2+ And removing impurities to obtain a gypsum product with small particle size and good dispersibility, wherein the obtained purified mother liquor can be directly reused in the iron phosphate production process, and a high-purity monoammonium phosphate or monosodium phosphate product can also be obtained by one-time crystallization, so that the cyclic utilization of ammonium/sodium, phosphorus and water resources is realized.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for purifying and recovering iron phosphate mother liquor comprises the following steps:
s1, pulping: mixing the iron phosphate mother liquor and calcium hydrophosphate to prepare pulp, wherein the adding amount of the calcium hydrophosphate is SO in the mother liquor 4 2- 1 to 1.5 times of the molar content of (A);
s2, transformation and separation: slowly adding a sulfuric acid solution into the slurry obtained in the step S1 for reaction, and controlling SO in a reaction system 4 2- ：Ca 2+ The molar ratio is 1-1.2: 1, the reaction temperature is 50-80 ℃, the reaction time is 2-5 h, and the sulfuric acid is of industrial grade; filtering after the reaction is finished to obtain high white gypsum and filtrate 1;
s3, secondary transformation and separation: slowly adding calcium hydrophosphate into the filtrate 1 obtained in the step S2 for reaction, wherein the adding amount is SO in the filtrate 1 4 2- 2-5 times of the molar content, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
s4, impurity separation: adding ammonia water or a sodium-containing alkaline substance into the filtrate 2 obtained in the step S3 to adjust the pH, controlling the reaction pH to be 4.5-6, and filtering after the reaction is finished to obtain filter residue and purified mother liquor; the sodium-containing alkaline substance is sodium hydroxide or sodium carbonate or a mixture of the sodium hydroxide and the sodium carbonate;
the method further comprises the following steps: s5, crystallization: adding phosphoric acid into the purified mother liquor obtained in the step S4 to adjust the pH value, controlling the reaction pH value to be 4.2-4.6, and crystallizing after the reaction is finished to obtain a phosphate product; the initial temperature of cooling crystallization is 60-80 ℃, and the cooling rate is 0.1-0.4 ℃/min.
In addition, the method can also recycle the purified mother liquor obtained in the step S4 to the iron phosphate production process.
Specifically, the calcium hydrophosphate of the invention is feed grade calcium hydrophosphate; both sulfuric acid and phosphoric acid are technical grade.
The inventor creatively proposes the idea of producing calcium sulfate gypsum in batches by respectively adding calcium hydrophosphate and sulfuric acid in two steps when purifying the ferric phosphate mother liquor, and finally preparing thinner gypsum; mainly because: (1) Firstly, in the pulping process of the step S1, sulfate radicals in the ferric phosphate mother liquor react with calcium hydrophosphate to generate gypsum; in step S2, the slurry reacts with sulfuric acid to generate gypsum again. The mode of generating the gypsum by two steps is adopted, so that the gypsum has small particle size and good dispersity in the whole process, and the gypsum is prevented from being coated on the surface of the calcium hydrophosphate; (2) And step S2, slowly adding sulfuric acid into the slurry mixed in the step S1 to slowly generate gypsum, so that the condition that the gypsum is coated on the surface of calcium hydrophosphate as a result of fast contact of reactants to generate gypsum is avoided.
In addition, compared with the operation of dissolving calcium hydrophosphate by adopting phosphoric acid in the prior art, the calcium hydrophosphate is dissolved by adopting sulfuric acid in the method, so that gypsum can be generated by a two-step method, and the cost of sulfuric acid is far lower than that of phosphoric acid; meanwhile, calcium impurities in the solution can be further removed by adopting sulfuric acid to dissolve calcium hydrogen phosphate, so that the purity of the product is improved.
The contents of calcium ions, phosphate radicals, sulfate radicals and other substances in the solution system are reasonably controlled through the two steps of the step S3 and the step S4, the operation is carried out under the condition of a lower pH value, impurities such as calcium, magnesium, iron, aluminum, sulfate radicals and the like in the solution can be well removed, and compared with the traditional method of removing metal ions through the operation of raising the pH value, the acid and alkali consumption can be greatly saved.
The invention has the beneficial effects that:
1. in the reaction system, the gypsum is generated in two steps, the gypsum has small particle size and good dispersibility in the whole process, is not easy to wrap the surface of calcium hydrophosphate, avoids incomplete reaction of the calcium hydrophosphate and mother liquor, avoids raw material loss and improves the recovery rate of phosphorus; the purified mother liquor obtained by the purification and recovery method can be directly reused in the iron phosphate production process, high-purity monoammonium phosphate or monosodium phosphate products can be obtained by only once crystallization, and gypsum products with small particle size and good dispersibility can be obtained, so that the cyclic utilization of ammonium/sodium, phosphorus and water resources is realized.
2. The invention makes SO in the mother liquor through a series of reactions 4 2- 、Fe 3+ 、Al 3+ 、Mg 2+ Removing impurities, and preparing a beneficial monoammonium phosphate or monosodium phosphate product, so that the mother solution can be reused for producing the iron phosphate, thereby realizing the production of ammonium, sodium and phosphorusAnd recycling the source. The purification process avoids the evaporation concentration process, reduces the energy consumption and water consumption of the whole system, and greatly reduces the treatment cost of the iron phosphate waste liquid. In the process of mother liquor purification, calcium hydrogen phosphate with lower cost is introduced as a phosphorus source and is converted into the mother liquor for the production of industrial monoammonium phosphate/sodium, and compared with the production of monoammonium phosphate by using commercial phosphoric acid as the phosphorus source, the process greatly reduces the cost of the phosphorus source.
Drawings
Fig. 1 is a process flow diagram for purifying and recovering ferric phosphate mother liquor of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the present invention is further described with reference to specific embodiments. Those whose conditions are not specified in the examples were carried out according to the conventional conditions or conditions recommended by the manufacturer. The reagents used, or those not indicated together with the manufacturer, are conventional products which are commercially available. All features disclosed in this specification may be combined in any combination, except features or/and steps which are mutually exclusive.
The following examples are presented to enable those skilled in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The calcium hydrogen phosphate in the following examples and comparative examples is feed grade calcium hydrogen phosphate; both sulfuric acid and phosphoric acid are technical grade.
Example 1
The embodiment provides a method for purifying and recovering iron phosphate mother liquor, which comprises the following steps:
1. mixing the ferric phosphate mother liquor with feed-grade calcium hydrophosphate to prepare pulp, and CaHPO 4 The addition amount is SO in the mother liquor 4 2- 1.5 times of the molar content;
2. slowly adding sulfuric acid into the slurry for reaction, and controlling SO in a reaction system 4 2- ：Ca 2+ The molar ratio is 1:1, reacting at 50 ℃ for 2 hours, and filtering after the reaction is finished to obtain high white gypsum and filtrate 1;
3. slowly adding feed-grade calcium hydrophosphate into the filtrate 1 for reaction, wherein the adding amount is SO in the filtrate 1 4 2- 2 times of the molar content, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
4. adding ammonia water into the filtrate 2 to adjust the pH, controlling the reaction pH to be 4.5, and filtering after the reaction is finished to obtain filter residue and purified mother liquor;
5. adding phosphoric acid into the purified mother liquor to adjust the pH value, controlling the reaction pH value to be 4.2, and after the reaction is finished, sending the product to crystallization to obtain an industrial grade monoammonium phosphate product.
Example 2
1. Mixing the ferric phosphate mother liquor with feed-grade calcium hydrophosphate to prepare pulp, and CaHPO 4 The addition amount of SO in the mother liquor 4 2- 1.3 times of the molar content;
2. slowly adding sulfuric acid into the slurry for reaction, and controlling SO in a reaction system 4 2- ：Ca 2+ Is that 2:1, reacting at the temperature of 70 ℃ for 4 hours, and filtering after the reaction is finished to obtain high white gypsum and filtrate 1;
3. slowly adding feed-grade calcium hydrophosphate into the filtrate 1 for reaction, wherein the adding amount is SO in the filtrate 1 4 2- 3 times of the molar content, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
4. adding ammonia water into the filtrate 2 to adjust the pH value, controlling the reaction pH value to be 5.0, and filtering after the reaction is finished to obtain filter residues and purified mother liquor;
5. adding phosphoric acid into the purified mother liquor to adjust the pH value, controlling the reaction pH value to be 4.6, and after the reaction is finished, sending the solution to be crystallized to obtain an industrial grade monoammonium phosphate product.
Example 3
1. Mixing the ferric phosphate mother liquor with feed-grade calcium hydrophosphate to prepare pulp, caHPO 4 The addition amount is SO in the mother liquor 4 2- 1.2 times of the molar content;
2. slowly adding sulfuric acid into the slurry for reaction, and controlling SO in a reaction system 4 2- ：Ca 2+ Is 1.2:1, reacting at the temperature of 80 ℃ for 3 hours, and filtering after the reaction is finished to obtain high white gypsum and filtrate 1;
3. slowly adding feed-grade calcium hydrophosphate into the filtrate 1 for reaction, wherein the adding amount is SO in the filtrate 1 4 2- 3 times of the molar content, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
4. slowly adding ammonia water into the filtrate 2 to adjust the pH value, controlling the reaction pH value to be 6, and filtering after the reaction is finished to obtain filter residue and purified mother liquor;
5. adding phosphoric acid into the purified mother liquor to adjust the pH value, controlling the reaction pH value to be 4.4, and after the reaction is finished, sending the solution to be crystallized to obtain an industrial grade monoammonium phosphate product.
Example 4
1. Mixing the ferric phosphate mother liquor with feed-grade calcium hydrophosphate to prepare pulp, caHPO 4 The addition amount of SO in the mother liquor 4 2- 1 time of the molar content;
2. slowly adding sulfuric acid into the slurry for reaction, and controlling SO in a reaction system 4 2- ：Ca 2+ Is 1:1, the reaction temperature is 50 ℃, and the reaction time is 4h; filtering after the reaction is finished to obtain high white gypsum and filtrate 1;
3. slowly adding feed-grade calcium hydrophosphate into the filtrate 1 for reaction, wherein the adding amount is SO in the filtrate 1 4 2- 5 times of the molar content, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
4. adding ammonia water into the filtrate 2 to adjust the pH value, controlling the reaction pH value to be 5.5, and filtering after the reaction is finished to obtain filter residues and purified mother liquor;
5. adding phosphoric acid into the purified mother liquor to adjust the pH value, controlling the reaction pH value to be 4.2, and after the reaction is finished, sending the solution to be crystallized to obtain an industrial-grade monoammonium phosphate product.
Example 5
The present example differs from example 1 in that:
adding sodium hydroxide to adjust the pH value in the step 4; and 5, obtaining the industrial-grade monosodium phosphate as a product.
Comparative example 1
The comparative example differs from example 1 in that: in step 2, SO in the reaction system is controlled 4 2- ：Ca 2+ Is 0.8:1.
comparative example 2
The comparative example differs from example 1 in that: step 3 is not included, i.e. the second calcium hydrogen phosphate addition treatment reaction to the filtrate 1 is omitted.
Comparative example 3
This comparative example differs from example 1 in that: step 4 was omitted, i.e., the treatment of filtrate 2 with the addition of an alkaline solution to adjust the pH was omitted.
Examples of the experiments
The purified mother liquor, gypsum and product components prepared in the above examples and comparative examples were analyzed and compared, and the results are shown in tables 1, 2, 3 and 4, respectively:
table 1 test results of purified mother liquor in each example and comparative example
TABLE 2 test results of Gypsum in each of examples and comparative examples
TABLE 3 test results of the products of examples 1 to 4 and comparative examples 1 to 3
Table 4 test results for the product of example 5
In conclusion, after the application purifies the ferric phosphate mother liquor, SO in the ferric phosphate mother liquor can be purified 4 2- 、Fe 3+ 、Al 3+ 、Mg 2+ Removing impurities to obtain a gypsum product with small particle size and good dispersibility, wherein the obtained purified mother liquor can be directly reused in an iron phosphate production process, and also can obtain a high-purity monoammonium phosphate or monosodium phosphate product only through one-time crystallization, and the monoammonium phosphate products prepared by treating the iron phosphate mother liquor in embodiments 1-4 of the invention can reach the HG/T4133-2010I product standard; in example 5, the monosodium phosphate product prepared by treating the iron phosphate mother liquor reaches the industrial standard of HG/T2767-2009I products.
The present invention is not limited to the above embodiments, and any structural changes made under the teaching of the present invention shall fall within the protection scope of the present invention, which has the same or similar technical solutions as the present invention.
Claims (10)
1. The method for purifying and recovering the iron phosphate mother liquor is characterized by comprising the following steps:
s1, pulping: mixing the iron phosphate mother liquor and calcium hydrophosphate to prepare slurry;
s2, transformation and separation: slowly adding a sulfuric acid solution into the slurry obtained in the step S1 for reaction, and filtering after the reaction is finished to obtain gypsum and a filtrate 1;
s3, secondary transformation and separation: slowly adding calcium hydrogen phosphate into the filtrate 1 obtained in the step S2 for reaction, and filtering after the reaction is finished to obtain filter residue and filtrate 2;
s4, impurity separation: and (4) adding alkali liquor into the filtrate 2 obtained in the step (S3) to adjust the pH value, controlling the reaction pH value to be 4.5-6, and filtering after the reaction is finished to obtain filter residue and purified mother liquor.
2. The method for purifying and recovering iron phosphate mother liquor according to claim 1, further comprising:
s5, crystallization: and (5) adding phosphoric acid into the purified mother liquor obtained in the step (S4) to adjust the pH value, controlling the reaction pH value to be 4.2-4.6, and crystallizing after the reaction is finished to obtain a phosphate product.
3. The method for purifying and recovering iron phosphate mother liquor according to claim 1, further comprising:
and (5) recycling the purified mother liquor obtained in the step (S4) to the iron phosphate production process.
4. The method for purifying and recovering iron phosphate mother liquor according to claim 1, wherein in step S1, the amount of calcium hydrogen phosphate added is SO in the iron phosphate mother liquor 4 2- 1 to 1.5 times of the molar content of (A).
5. The method for purifying and recovering iron phosphate mother liquor according to claim 1, wherein in step S2, SO in the reaction system 4 2- ：Ca 2+ The molar ratio is 1-1.2: 1, said SO 4 2- From SO in the ferric phosphate mother liquor of step S1 4 2- And sulfuric acid from step S2.
6. The method for purifying and recovering iron phosphate mother liquor according to claim 1, wherein in step S2, the reaction temperature is 50 to 80 ℃ and the reaction time is 2 to 5 hours.
7. The method for purifying and recovering iron phosphate mother liquor according to claim 1, wherein in step S3, the amount of calcium hydrogen phosphate added is SO in filtrate 1 4 2- 2 to 5 times of the molar content.
8. The method for purifying and recovering iron phosphate mother liquor according to claim 1, wherein the alkali liquor in S4 is ammonia water or a sodium-containing alkaline substance.
9. The method for purifying and recovering iron phosphate mother liquor according to claim 8, wherein the sodium-containing alkaline substance in S4 is sodium hydroxide, sodium carbonate or a mixture of the sodium hydroxide and the sodium carbonate.
10. The method for purifying and recovering iron phosphate mother liquor according to claim 2, wherein in the step S5, the initial temperature of cooling crystallization is 60 to 80 ℃, and the cooling rate is 0.1 to 0.4 ℃/min.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20190322540A1 (en) * | 2016-06-23 | 2019-10-24 | Prayon Technologies | Method for producing calcium sulfate |
| CN113307243A (en) * | 2021-07-08 | 2021-08-27 | 河南佰利新能源材料有限公司 | Method for preparing iron phosphate by recycling mother liquor |
| CN113354177A (en) * | 2021-07-06 | 2021-09-07 | 杭州逐真科技有限公司 | System and method for full-element resource treatment of iron phosphate ammonia nitrogen-containing wastewater |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20190322540A1 (en) * | 2016-06-23 | 2019-10-24 | Prayon Technologies | Method for producing calcium sulfate |
| CN113354177A (en) * | 2021-07-06 | 2021-09-07 | 杭州逐真科技有限公司 | System and method for full-element resource treatment of iron phosphate ammonia nitrogen-containing wastewater |
| CN113307243A (en) * | 2021-07-08 | 2021-08-27 | 河南佰利新能源材料有限公司 | Method for preparing iron phosphate by recycling mother liquor |
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