CN114956025A - Preparation process of feed-grade monocalcium phosphate - Google Patents
Preparation process of feed-grade monocalcium phosphate Download PDFInfo
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- CN114956025A CN114956025A CN202210262414.6A CN202210262414A CN114956025A CN 114956025 A CN114956025 A CN 114956025A CN 202210262414 A CN202210262414 A CN 202210262414A CN 114956025 A CN114956025 A CN 114956025A
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- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 title claims abstract description 41
- 235000019691 monocalcium phosphate Nutrition 0.000 title claims abstract description 41
- 239000001506 calcium phosphate Substances 0.000 title claims abstract description 27
- 229910000150 monocalcium phosphate Inorganic materials 0.000 title claims abstract description 27
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 96
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 48
- 239000002367 phosphate rock Substances 0.000 claims abstract description 47
- 239000011575 calcium Substances 0.000 claims abstract description 45
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229960005069 calcium Drugs 0.000 claims abstract description 42
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 42
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000011265 semifinished product Substances 0.000 claims abstract description 28
- 239000002002 slurry Substances 0.000 claims abstract description 23
- 239000000047 product Substances 0.000 claims abstract description 16
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 229940062672 calcium dihydrogen phosphate Drugs 0.000 claims abstract description 14
- 229910000389 calcium phosphate Inorganic materials 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 13
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 239000011574 phosphorus Substances 0.000 claims abstract description 9
- 238000000926 separation method Methods 0.000 claims abstract description 9
- 150000004683 dihydrates Chemical class 0.000 claims abstract description 8
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 6
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 6
- 238000001723 curing Methods 0.000 claims abstract description 6
- 239000004571 lime Substances 0.000 claims abstract description 6
- 239000008267 milk Substances 0.000 claims abstract description 6
- 210000004080 milk Anatomy 0.000 claims abstract description 6
- 235000013336 milk Nutrition 0.000 claims abstract description 6
- 238000012216 screening Methods 0.000 claims abstract description 4
- 230000003472 neutralizing effect Effects 0.000 claims abstract 2
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 claims description 52
- 229910019142 PO4 Inorganic materials 0.000 claims description 20
- 239000010452 phosphate Substances 0.000 claims description 20
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 20
- 238000004519 manufacturing process Methods 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000000605 extraction Methods 0.000 claims description 12
- 238000006115 defluorination reaction Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 30
- 230000008569 process Effects 0.000 abstract description 12
- 239000003245 coal Substances 0.000 abstract description 6
- 239000000126 substance Substances 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 description 13
- 238000000746 purification Methods 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 description 9
- 235000019700 dicalcium phosphate Nutrition 0.000 description 9
- 239000007790 solid phase Substances 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 4
- -1 calcium hydrogen Chemical class 0.000 description 3
- 238000004134 energy conservation Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000004062 sedimentation Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- 239000012065 filter cake Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- ZHQXROVTUTVPGO-UHFFFAOYSA-N [F].[P] Chemical compound [F].[P] ZHQXROVTUTVPGO-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 239000012629 purifying agent Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012066 reaction slurry Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000003809 water extraction Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
- C01B25/325—Preparation by double decomposition
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Fertilizers (AREA)
Abstract
The invention belongs to the field of phosphorus chemical industry, and particularly relates to a preparation process of feed-grade monocalcium phosphate, which comprises the following steps: (1) extracting phosphorite with grade of 14-25% by using dihydrate, purifying to prepare phosphoric acid I, neutralizing the generated calcium hydrophosphate slurry by using the phosphoric acid I and lime milk, performing solid-liquid separation on the calcium hydrophosphate slurry to obtain a semi-finished product of calcium hydrophosphate, and drying to obtain calcium hydrophosphate with moisture content of less than 4%; (2) extracting phosphorite with a grade higher than 29% by using semi-water-dihydrate, concentrating, defluorinating and dearsenifying to obtain phosphoric acid II with a concentration of more than 50%; (3) and (3) reacting the phosphoric acid II obtained in the step (2) with the calcium hydrophosphate obtained in the step (1) to generate a calcium dihydrogen phosphate semi-finished product, curing, drying, and screening to obtain a calcium dihydrogen phosphate finished product. The invention can use a large amount of low-grade phosphorite which is difficult to apply in the traditional process, reduce the use proportion of the high-grade phosphorite, and save about 45 percent of coal consumption per unit product.
Description
Technical Field
The invention belongs to the field of phosphorus chemical industry, and particularly relates to a preparation process of feed-grade monocalcium phosphate.
Background
(1) Energy-saving and carbon-reducing method
The method is characterized by establishing a new development stage, completely, accurately and comprehensively implementing a new development concept, constructing a new development pattern, insisting on a system concept, processing the relations of development and emission reduction, whole and local, short-term and medium-term, and overall and stable growth and adjustment structure, bringing carbon peak reaching, carbon neutral and into the overall development of the economic society, insisting on the general guideline of 'overall nationwide, priority saving, double-wheel driving, smooth inside and outside and risk prevention', effectively and orderly doing carbon peak reaching work, defining target tasks of all regions, all fields and all industries, accelerating the realization of green change of production and life modes, promoting the economic society development to be established on the basis of efficient utilization of resources and green low-carbon development, and ensuring that the carbon peak reaching target is realized before 2030 years.
(2) The current state of the industry:
calcium dihydrogen phosphate is generally produced by a calcium powder method (also called a one-step method or a concentration one-step method), and the main process is as follows: preparing wet-process phosphoric acid from high-grade phosphate ore by a dihydrate method, a semi-hydrate method and a dihydrate-semi-hydrate method; then concentrating the phosphoric acid (if a dihydrate method is adopted, the concentration of the finished phosphoric acid is low, and the energy consumption is high during concentration); purifying the concentrated phosphoric acid; reacting purified phosphoric acid with calcium carbonate to prepare slurry; filtering to obtain filter cake and filtrate; and continuously adding phosphoric acid into the filter cake to generate a feed-grade monocalcium phosphate semi-finished product, and performing spray drying to obtain a finished product.
(3) Depletion of phosphate rock
According to the preliminary statistics of 64-65 pages of data of 'latest phosphorus chemical engineering technical manual' published by Chinese knowledge publisher 2013 in 8 months, the I-grade rich ore with the phosphorus pentoxide content of more than 30% in China is only 12.98 hundred million tons, and accounts for 6.4% of the national reserves; 15 hundred million tons of II-grade middlings with 24-30 percent of phosphorus pentoxide account for 7.4 percent of national reserves; 148 hundred million tons of grade III lean ore with phosphorus pentoxide content of 14-24% accounts for 72.9% "of national reserves.
(4) Policy guidance
Technical transformation and upgrading investment guidelines for industrial enterprises (2019 edition) encourage ' strengthening utilization of medium and low-grade phosphorite and phosphorite associated resources ', ' industrial transformation and upgrading planning in Yunnan province (2016 and 2020) ' support fractional utilization of phosphorite resources, encourage comprehensive utilization of medium and low-grade phosphorite, ' industrial structure adjustment instruction catalog (2019 edition) ' encouragement of class/eleven, petrochemical industry/2/medium and low-grade phosphorite utilization '. In order to effectively utilize middle-low grade phosphorite and achieve the purpose of energy conservation and carbon reduction, a method for preparing calcium dihydrogen phosphate by utilizing middle-low grade phosphorite under the condition of energy conservation and carbon reduction is urgently needed to be researched.
Disclosure of Invention
In order to solve the technical problems, the invention provides a preparation process of feed-grade monocalcium phosphate, which effectively utilizes medium-grade and low-grade phosphorite to prepare monocalcium phosphate under the conditions of energy conservation and carbon reduction.
The specific technical scheme is as follows: a preparation process of feed-grade monocalcium phosphate comprises the following steps:
(1) phosphate rock with the grade of 14-25 percent calculated by phosphorus pentoxide is adopted, phosphoric acid I is prepared by purification after extraction with dihydrate, then the phosphoric acid I and lime milk are neutralized to generate calcium hydrophosphate slurry, the calcium hydrophosphate slurry is subjected to solid-liquid separation to obtain a calcium hydrophosphate semi-finished product, and the calcium hydrophosphate semi-finished product is dried firstly to obtain calcium hydrophosphate with the moisture content of less than 4 percent;
(2) phosphate ore with the grade higher than 29 percent calculated by phosphorus pentoxide is used, and phosphoric acid II with the concentration higher than 50 percent calculated by phosphorus pentoxide is obtained after semi-water-dihydrate extraction, concentration, defluorination and dearsenification;
(3) and (3) reacting the phosphoric acid II obtained in the step (2) with the calcium hydrophosphate obtained in the step (1) to generate a calcium dihydrogen phosphate semi-finished product, curing, drying, and screening to obtain a calcium dihydrogen phosphate finished product.
Further, in the step (1), the concentration of the phosphoric acid I prepared by the purification after the extraction with the dihydrate is 16 to 18 percent based on the phosphorus pentoxide.
Further, in the step (1), the calcium hydrophosphate slurry is subjected to solid-liquid separation to obtain a calcium hydrophosphate semi-finished product, wherein the moisture content of the calcium hydrophosphate semi-finished product is less than 20%. The feed-grade monocalcium phosphate is called as a traditional term, and is called as feed-grade additive monocalcium phosphate by a professional term (GB 22548-2017).
Further, in the step (3), the generated monocalcium phosphate semi-finished product has 9-11% of moisture content, and is cured and dried.
Furthermore, the phosphate ore with the grade of 14-25% is selected from grade III phosphate ore with the phosphorus pentoxide content of 14-24% or grade II phosphate ore with the phosphorus pentoxide content of 24-25%, namely grade II phosphate ore with the grade III or slightly higher than grade III.
Furthermore, the phosphorite with the grade higher than 29 percent is selected from grade I phosphorite with the phosphorus pentoxide content of more than 30 percent or grade II phosphorite with the phosphorus pentoxide content of 29-30 percent, namely selected from grade I phosphorite or grade II phosphorite close to grade I phosphorite.
Has the beneficial effects that:
under the era background of 2030 carbon peak reaching, energy saving and emission reduction and energy consumption double control, and the guidance of numerous national industrial policies, enterprises are required to develop towards the utilization and energy saving of middle-low grade phosphorite. Under the background requirement of the times, the invention independently develops a set of production process which can utilize middle-low grade phosphorite, save energy and reduce carbon.
(1) In the process, the water content of each monocalcium phosphate semi-finished product is calculated according to the median of 11.5%, and the water content required for drying each ton of monocalcium phosphate finished products is as follows: 1/(1-11.5%) 11.5% =0.12994 tons; the production of one ton of calcium dihydrogen phosphate requires about 0.65 ton of calcium hydrophosphate, the moisture content of the semi-finished product of calcium hydrophosphate is about 23 percent, and the moisture required for drying 0.65 ton of calcium dihydrogen phosphate is 0.65/(1-23%) 23% =0.1942 tons; in the process, the water required to be dried for producing one ton of monocalcium phosphate semi-finished product is 0.1942+0.1299=0.324 ton, compared with the prior art, the water required to be dried for producing one ton of monocalcium phosphate semi-finished product is reduced by 0.494 ton after the technology is improved, and the coal consumption can be reduced by about 80% theoretically, but because the tail gas carries away part of heat and the heat dissipation of a system is similar, the coal consumption of a unit product in the actual production process is reduced from 124kgce/t to 68kgce/t, and 56kgce/t is saved, which is equivalent to about 45% of coal consumption.
(2) And (4) theoretical calculation: CaHPO 4 + H 3 PO 4 =Ca(H 2 PO 4 ) 2 50% of phosphorus is derived from calcium hydrogen phosphate, and according to the data from the beginning of production in 5-10 months in 2021, 50% of phosphorus in the calcium dihydrogen phosphate product is derived from phosphoric acid, but in the actual production process, 55.51% of phosphorus pentoxide consumption is derived from phosphoric acid, and 44.49% of phosphorus pentoxide is derived from calcium hydrogen phosphate, namely 10% of phosphorus is derived from the existing process in the industryCompared with the phosphate ore with higher use grade of 0%, the production process disclosed by the patent has the advantages that 55.51% of the phosphate ore is the medium-high grade phosphate ore, 44.49% of the phosphate ore is the low-grade phosphate ore, and a large amount of low-grade phosphate ore is used, so that the guide of national industrial policies is met, and the actual requirements of enterprise development are met.
(3) And (3) economic analysis: the market price of the existing 32 percent grade phosphorite is 950 yuan/ton, the market price of the 29 percent grade phosphorite is 780 yuan/ton, the market price of the 23 percent grade phosphorite is 310 yuan/ton, the cost of producing the raw material phosphorite by adopting the calcium hydrogen method is reduced by over 440 yuan/ton compared with the calcium powder method, 56 kilograms of standard coal (about 94 yuan/ton) is saved, the power consumption is reduced by about 10 yuan/ton, and the yield is calculated by 20 ten thousand tons, which is equivalent to that 20 ten thousand tons (440 +94+ 10) are saved by about 1 hundred million yuan. Meanwhile, the production by adopting a calcium hydrogen method reduces the links of pulping, size mixing, spraying and tail gas circular washing, greatly reduces the working procedures, and also reduces the investment (taking a 20 ten thousand ton device as an example, the investment is saved by about 2400 ten thousand yuan) and the energy consumption of the links in the traditional working procedures; particularly, in order to realize spray granulation in the traditional process, a large amount of water is required to be added for size mixing until the concentration is 45-50%, and finally a large amount of water is evaporated; the powdery monocalcium phosphate prepared by firstly preparing the calcium hydrophosphate and then adding the high-concentration phosphoric acid can avoid the operation of firstly adding water and then evaporating, thereby saving most energy consumption.
The invention can use a large amount of low-grade phosphorite which is difficult to apply in the traditional process, reduce the use proportion of the high-grade phosphorite, save about 45 percent of coal consumption per unit product and obtain better economic benefit.
Drawings
FIG. 1 is a schematic diagram comparing the present invention with a conventional process.
Detailed Description
A preparation process of feed-grade monocalcium phosphate comprises the following steps:
(1) phosphate rock with the grade of 14-25 percent calculated by phosphorus pentoxide is adopted, phosphoric acid I is prepared by purification after extraction with dihydrate, then the phosphoric acid I and lime milk are neutralized to generate calcium hydrophosphate slurry, the calcium hydrophosphate slurry is subjected to solid-liquid separation to obtain a calcium hydrophosphate semi-finished product, and the calcium hydrophosphate semi-finished product is dried firstly to obtain calcium hydrophosphate with the moisture content of less than 4 percent;
(2) utilizing phosphorite with the grade higher than 29 percent calculated by phosphorus pentoxide to obtain phosphoric acid II with the concentration of more than 50 percent calculated by phosphorus pentoxide through semi-water-dihydrate extraction, concentration, defluorination and dearsenification;
(3) and (3) reacting the phosphoric acid II obtained in the step (2) with the calcium hydrophosphate obtained in the step (1) to generate a calcium dihydrogen phosphate semi-finished product, curing, drying, and screening to obtain a calcium dihydrogen phosphate finished product.
Further, in the step (1), the concentration of the phosphoric acid I prepared by the secondary extraction and purification of the dihydrate is 16-18 percent based on the phosphorus pentoxide.
Further, in the step (1), the calcium hydrophosphate slurry is subjected to solid-liquid separation to obtain a calcium hydrophosphate semi-finished product, wherein the moisture content of the calcium hydrophosphate semi-finished product is less than 20%.
Further, in the step (3), the generated monocalcium phosphate semi-finished product has 9-11% of moisture content, and is cured and dried.
Furthermore, the phosphate ore with the grade of 14-25% is selected from grade III phosphate ore with the phosphorus pentoxide content of 14-24% or grade II phosphate ore with the phosphorus pentoxide content of 24-25%, namely grade II phosphate ore with the grade III or slightly higher than grade III.
Furthermore, the phosphorite with the grade higher than 29 percent is selected from grade I phosphorite with the phosphorus pentoxide content of more than 30 percent or grade II phosphorite with the phosphorus pentoxide content of 29-30 percent, namely selected from grade I phosphorite or grade II phosphorite close to grade I phosphorite.
Example (since calcium in the calcium dihydrogen phosphate product is derived from calcium hydrogen phosphate, the calcium hydrogen method is abbreviated)
(1) Selecting grade III phosphorite or phosphorite slightly higher than grade II phosphorite with grade 14-25%, feeding into ball mill, adding water or process circulating water into the ball mill, and adjusting water addition amount to obtain phosphorite slurry with water content of 40-42%;
(2) the reaction of the phosphorite pulp and sulfuric acid in the extraction tank:
Ca 5 F(PO 4 ) 3 +5H 2 SO 4 +mH 2 O==3H 3 PO 4 +5CaSO 4 .m/5H 2 o + HF, the reaction being carried out in two steps, the first: ca 5 F(PO 4 ) 3 +7H 3 PO 4 ==5Ca(H 2 PO 4 ) 2 + HF, second step:
5Ca(H 2 PO 4 ) 2 +5H 2 SO 4 +mH 2 O==10H 3 PO 4 +5CaSO 4 .m/5H 2 o, performing solid-liquid separation on the slurry after the reaction, wherein the liquid phase is dilute phosphoric acid and enters a dilute phosphoric acid storage tank; solid-liquid separation and solid-phase treatment: the solid phase enters an extraction tank to react with the phosphoric acid and the sulfuric acid returned by the filtration, and after the reaction is finished, the solid phase is obtained by filtration and washing, and the liquid phase part returns to the extraction tank.
(3) Reacting the prepared dilute phosphoric acid with calcium slurry: 2H 3 PO 4 +CaCO 3 =Ca(H 2 PO 4 ) 2 +CO 2 +H 2 After the O reaction, the qualified product enters a clarifier to be clarified, and clear liquid overflows to a buffer storage tank to be subjected to secondary purification treatment; the solid phase of the thick slurry at the bottom is a fertilizer grade calcium hydrophosphate product (which can be sold) after solid phase separation.
(4) The clear liquid after the primary purification and sedimentation enters a secondary purification reaction tank to react with lime milk, the PH value of the reaction end point is controlled to be 2.8-3.0, after the secondary purification reaction, the slurry enters a sedimentation device for sedimentation after the purification is qualified, the settled clear liquid is phosphoric acid I (the phosphorus-fluorine ratio is more than 240) to be neutralized in three sections, and the solid phase is fertilizer-grade calcium hydrophosphate product (which can be sold) after the solid phase separation of thick slurry at the bottom.
(5) Reacting the qualified phosphoric acid I subjected to secondary purification treatment with lime milk in an ash dissolving process in a neutralization reaction tank, controlling the pH value at the end point of reaction to be between 5.7 and 6.0, removing reaction slurry in a three-section settler, removing clear liquid in four sections for neutralization and then supplying to the ash dissolving process, separating thick slurry by a centrifuge, and conveying filtered solid products to drying; returning a part of mother liquor pool of the clear liquid of the three-section settler by a pump for recycling; and (3) separating the thick slurry to obtain a calcium hydrogen phosphate semi-finished product, requiring the water content to be less than 20%, conveying the calcium hydrogen phosphate semi-finished product to a drying section through a belt, and drying the calcium hydrogen phosphate semi-finished product until the water content is less than 4% to obtain the calcium hydrogen phosphate with the water content of less than 4%.
(6) Selecting grade I phosphorite or grade II phosphorite close to grade I, i.e. reacting phosphorite powder with grade higher than 29% with sulfuric acid in a semi-hydrated extraction tank to generate phosphoric acid and semi-hydrated gypsum slurry, and filtering and washing the slurry by a belt filter to obtain concentrated phosphoric acid with concentration of about 39%.
(7) Concentrated phosphoric acid is concentrated to remove fluorine and then reacts in a purification reaction tank under the condition of adding steam and a purifying agent, and the main principle is that fluorine in wet-process phosphoric acid mainly adopts HF and H 2 SiF 6 In the form of (a), under heated conditions: 6HF + SiO 2 = H 2 SiF 6 + 2H 2 O、H 2 SiF 6 =SiF 4 +2HF, SiF produced 4 The liquid surface is taken out in the collision of the steam and the acid, enters a washing tower through the negative pressure of the system, and is in countercurrent contact with water in the washing tower to generate a fluosilicic acid solution: 3SiF 4 +（n+2）.H 2 O= 2H 2 SiF 6 + SiO 2 .n H 2 And O. And filtering the slurry qualified in the reaction by a plate frame, feeding the purified phosphoric acid II (the concentration of phosphorus pentoxide is more than 50%) into a storage tank, and transferring the sludge to a white fertilizer for sale after drying.
(8) Reacting phosphoric acid II with calcium hydrogen phosphate (the moisture content is less than 4%) in double-shaft stirring, controlling 1 ton of calcium hydrogen phosphate to be added into 0.5m of high-speed rail-produced phosphoric acid, crushing 2 tons of returned materials, then adjusting the adding amount of the returned materials and the adding amount of phosphoric acid according to the moisture content of the materials and production indexes, and controlling the moisture content of a semi-finished product to be 9-11%; and (3) feeding the semi-finished product into a curing warehouse, curing for about 100 hours, drying, sieving the dried material, packaging the sieved material to obtain a finished product of the monocalcium phosphate, and crushing the sieved material and returning the crushed product to the production process of the monocalcium phosphate.
Note: the concentration of phosphoric acid I prepared by purifying 14-25% grade phosphorite after secondary water extraction can be adjusted to 16-18%, and the concentration of phosphoric acid I is 16-18% because of the production requirement of reaction with phosphoric acid II; similarly, the concentration of the phosphoric acid II produced by the phosphorite with the grade higher than 29 percent through the semi-water-dihydrate extraction process can be adjusted to be more than 50 percent because of the concentration process, and the concentration of the phosphoric acid II is more than 50 percent because of the production requirement of the reaction with the phosphoric acid I.
Claims (6)
1. A preparation process of feed-grade monocalcium phosphate is characterized by comprising the following steps:
(1) extracting phosphate ore with a grade of 14-25% by using dihydrate, purifying to prepare phosphoric acid I, neutralizing the generated calcium hydrophosphate slurry by using the phosphoric acid I and lime milk, performing solid-liquid separation on the calcium hydrophosphate slurry to obtain a calcium hydrophosphate semi-finished product, and drying to obtain calcium hydrophosphate with the moisture content of less than 4%;
(2) utilizing phosphorite with the grade higher than 29 percent, and obtaining phosphoric acid II with the concentration higher than 50 percent through semi-hydrated-dihydrate extraction, concentration, defluorination and dearsenification;
(3) and (3) reacting the phosphoric acid II obtained in the step (2) with the calcium hydrophosphate obtained in the step (1) to generate a calcium dihydrogen phosphate semi-finished product, curing, drying, and screening to obtain a calcium dihydrogen phosphate finished product.
2. The process for preparing feed-grade monocalcium phosphate as claimed in claim 1, wherein in step (1), the concentration of phosphoric acid I obtained by diaextracting and purifying is 16-18%.
3. The process for preparing feed-grade monocalcium phosphate as claimed in claim 1, wherein in step (1), the water content of the calcium hydrophosphate semifinished product obtained by performing solid-liquid separation on calcium hydrophosphate slurry is less than 20%.
4. The process for preparing feed-grade monocalcium phosphate as claimed in claim 1, wherein in step (3), the produced monocalcium phosphate semi-finished product has a moisture content of 9-11%, and is dried after being cured.
5. The process for preparing feed-grade monocalcium phosphate as claimed in claim 1, wherein the grade of 14-25% phosphorus ore is selected from grade III phosphorus ore with phosphorus pentoxide content of 14-24% or grade II phosphorus ore with phosphorus pentoxide content of 24-25%.
6. The process for preparing feed-grade monocalcium phosphate as claimed in claim 1, wherein the phosphate ore with grade higher than 29% is selected from grade i phosphate ore with phosphorus pentoxide content higher than 30% or grade ii phosphate ore with phosphorus pentoxide content 29-30%.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116374975A (en) * | 2023-05-09 | 2023-07-04 | 四川大学 | Method for preparing monocalcium phosphate by directly decomposing phosphorite by phosphoric acid |
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