JPS60231407A - Manufacture of purified monoammonium phosphate from wet process phosphoric acid - Google Patents

Abstract

PURPOSE:To manufacture the titled compound in a high yield by sending a slurry contg. monoammonium phosphate crystals and insoluble sludge obtd. by reacting wet process phosphoric acid with NH3 to settling separators to separate a slurry contg. the insoluble sludge and by heating this slurry to dissolve monoammonium phosphate crystals contained in the slurry. CONSTITUTION:Wet process phosphoric acid and NH3 are fed to a reactor 3 from ducts 1, 2 in 0.9-1.35 molar ratio of NH3/H3PO4, and they are brought into a reaction at 50-80 deg.C. The resulting slurry contg. monoammonium phosphate crystals (a) and insoluble sludge (B) is sent to settling separators 4, 6 to separate a slurry contg. the component A from a slurry contg. the component B, and the slurry contg. the component A is sent to a centrifugal separator 13 to separate a filtrate. The slurry contg. the component B is heated to 60-95 deg.C with a heater 8 to dissolve the component A contained in the slurry, and a filtrate is separated from the insoluble sludge 10 with a centrifugal separator 9. The filtrate is sent to a circulation tank 12 and returned to the reactor 3 together with the filtrates sent from the separators 4, 13, and they are concentrated to form a slurry contg. monoammonium phosphate crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing purified ammonium phosphate from wet phosphoric acid. More particularly, the present invention relates to such a process for producing industrially usable ammonium phosphate directly from wet phosphoric acid in high yields.

Phosphoric acid obtained by reacting wet phosphorus with ammonia
Since ammonium contains many impurities derived from the phosphoric acid, it can be used as a fertilizer, but it cannot be used as it is for industrial purposes. In order to produce industrial purified ammonium phosphate (hereinafter referred to as ammonium phosphate) from wet phosphoric acid, it is necessary to purify the phosphoric acid in advance by the method described below.

That is, phosphoric acid is extracted from wet phosphoric acid by a solvent method, and the extracted material is reacted with ammonia to obtain phosphoric acid with less impurities.

However, this extraction method involves complicated steps and cannot be said to be industrially advantageous. On the other hand, regarding the various compounds that are produced stepwise by the reaction of wet phosphoric acid and ammonia, Ando et al.
According to "Research on Chemical Fertilizers" by Akiyama, published by May 208, 1976, by Nisshin Publishing Co., Ltd., regarding the ammonia neutralization of wet phosphoric acid, in relation to the neutralization conditions, (FeA
I) NH4)12 (PO4)2・+H20 (Note, abbreviated as Q compound) or (FeAI)NH4
) IF2 PO4 (note, abbreviated as S compound) is produced, and an ammonium phosphorus mother liquor obtained by removing Fe, AI, and F from wet phosphoric acid is obtained, and there is a possibility that industrial ammonium phosphorus can be produced from this. It is suggested. However, this method also has stepwise PH
It has the drawback that the process is long and energy consumption is high, including control, microprocessing, and crystallization process.

On the other hand, according to French Patent No. 1,248.05'5 (precon method), wet phosphoric acid is reacted with ammonia, crystals of ammonium phosphate are partially formed in the reaction solution, and the crystals are separated. The amount of impurities derived from wet phosphoric acid is reduced by cutting a portion of the mother liquor, and then by concentrating the mother liquor, crude crystals are crystallized, and the crude crystals are recrystallized. Refined products are obtained. The yield of purified ammonium phosphate obtained by this method is about 40 to 50% of the P content in the raw wet phosphoric acid, and the remaining P2O5 is ultimately used as ammonium phosphate for fertilizer. Become.

The phosphorus rancidity rate of ammonium phosphate (hereinafter referred to as ammonium phosphorus) in the above explanation is hereinafter defined as the extraction rate as follows.

As mentioned above, when wet phosphoric acid is directly neutralized, the phosphorus rancidity rate of purified ammonium phosphorus, that is, the extraction rate is considerably low.

In view of the above-mentioned problems with the known techniques, the present inventors have conducted intensive research in order to find a method for obtaining phosphoric acid-ammonium with a high yield, that is, a high extraction rate, by a wet phosphoric acid direct neutralization method. went.

As a result, wet phosphoric acid and ammonia were mixed into NH3/P, 0
5 while maintaining the molar ratio of 0.9 to 1.3.
The slurry containing phosphoric acid-ammonium crystals and insoluble sludge produced at completed the present invention after learning that ammonium phosphate could be obtained in high yield by concentrating the filtrate from which sludge had been removed by the method described below, and by combining the two. The method for treating the slurry containing the above-mentioned insoluble sludge is to heat the slurry to 60 to 95°C to dissolve the ammonium phosphate contained therein, and then centrifuge it to collect the filtrate. .

As is clear from the above description, an object of the present invention is to provide a method for obtaining ammonium phosphate in high yield from wet phosphoric acid. Another object is to provide phosphoric acid produced by the method.
The aim is to provide low prices.

The present invention has the following main configuration (1) and embodiment configuration (2).

(1) ■ Wet phosphoric acid in a reactor at a reaction temperature of 50 to 80
"Cj, NH3/H3PO4 molar ratio 0.9-1.3
Ammonia is reacted while maintaining the temperature of The crystals are obtained, the liquid to be separated is returned to the reactor, and the slurry containing the insoluble sludge portion is heated to 60 to 850 C to dissolve the ammonium phosphate crystals, and then centrifuged. The heated liquid to be separated is returned to the reactor, and the liquid returned to the reactor from steps (1) and (2) is concentrated to form a slurry containing phosphate-ammonium liquid crystals. A method for producing purified ammonium phosphoric acid from wet phosphoric acid, which comprises repeatedly performing the steps (1) to (2) described above.

(2) Before centrifuging the slurry containing the separated insoluble sludge portion, add 3 parts water to 100 parts by weight of the slurry.
(1) above, characterized in that 0 parts by weight or less are mixed.
The method described in section.

The configuration and effects of the present invention will be explained in detail below.

The wet phosphoric acid used in the present invention is the so-called wet phosphoric acid obtained by treating phosphate rock with mineral acid. Any method other than law may be used.

As the ammonia used in the present invention, it is most convenient to use gaseous ammonia and to blow it into the above-mentioned wet phosphoric acid. However, 3 times 20 to 30% by weight aqueous ammonia may also be used.

The woody feature of the method of the present invention lies in the organic combination of the following three points. First, wet phosphoric acid and ammonia were continuously supplied into the phosphoric acid-ammonium crystal slurry adjusted to a N1 (3/83 P04 molar ratio = 0.9 to 1.35) to maintain the molar ratio. At the same time, a slurry containing both ammonium phosphate crystals and insoluble sludge derived from impurities in the wet phosphoric acid is produced.Secondly, the aforementioned slurry is subjected to a fractionation method (Note).

For example, the mixture is separated into a portion containing ammonium phosphate and a portion containing insoluble sludge using a thickener, and the former is treated by a conventional method to obtain ammonium phosphate. Thirdly, the slurry containing the insoluble sludge separated as described above is heated to dissolve the ammonium phosphate crystals, and then centrifuged to separate the sludge and filtrate, and the filtrate is subjected to continuous ring concentration. Forms ammonium phosphate crystals.

As described above, impurity sludge can be efficiently separated and removed, and the yield of ammonium phosphate can be dramatically increased.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the figure, 1 is a wet phosphoric acid supply pipe, and 2 is an ammonia supply pipe. Wet phosphoric acid and ammonia are supplied to the reaction tank 3 to carry out a neutralization reaction. The supply ratio of both raw materials is 0.9 to 1.35 in terms of NH3/N3PO4 molar ratio.
Preferably it is 1.0-1.3, and the reaction temperature is 60-1.3.
80°C is preferred. When reacting at a temperature below 60°C,
Heat removal costs are high, and if the reaction is carried out at a temperature exceeding 80°C, temperature maintenance costs are high, making it uneconomical. In addition, when the temperature is outside the above-mentioned temperature range, the heat dissipating portions such as the reaction slurry extraction pipe are likely to be clogged with deposits of ammonium phosphate and the like. The above-mentioned neutralization reaction generates ammonium phosphorous slurry as a reaction mixture in the reaction tank 3. This slurry consists of ammonium phosphate crystals, ammonium phosphate mother liquor, and an insoluble sludge that is a collection of insoluble impurities. This phosphorus ammonium slurry is continuously or intermittently passed through the sedimentation separator 4.
and 6, and the slurry is separated into a slurry rich in phosphate-ammonium and a slurry rich in insoluble sludge.

The former is sent from 6 to a centrifugal separator 13, and phosphoric acid-ammonium (
Note: The product is separated into a purified product) and a filtrate, and ammonium phosphate is obtained as a product 14 after washing with a small amount of water, and the filtrate is sent to the circulation tank 12. Note that 5 is a slurry circulation pipe that serves as a bypass for adjusting the function of the sedimentation separator 4.6. The slurry containing a large amount of insoluble sludge separated in step 6 above is sent to heater 8 via piping 7 and heated to 60 to 95°C (note: 10 to 15°C higher than before entering heater 8). , all ammonium phosphate crystals contained in the slurry are dissolved. The heated slurry is then passed through a centrifugal separator 9 (for example, 20
00G or higher) to separate into insoluble sludge 10 and filtrate. This separation is carried out in the heater 8 described above, with 1
By adding and mixing 0 parts by weight or less of water from the pipe 1B, the process can be carried out smoothly and efficiently.

The sludge thus obtained still contains a considerable amount of phosphoric acid as a by-product and can be used as fertilizer or for other uses. The filtrate from the centrifugal separator 9 enters the circulation tank 12 via the pipe 11, is combined with the filtrate from the centrifugal separator 13 mentioned above, and is returned to the neutralization reaction tank 3 via the filtrate pipe 15. Such ring chaining of the filtrate is carried out continuously after the neutralization reaction tank (neutralization of wet phosphoric acid with ammonia → slurry production → slurry extraction, continuous or intermittent) has reached a steady state. This is reasonable because no separate concentration crystallization is required. Of course, ammonium phosphate can also be separately obtained by independently concentrating, cooling and crystallizing the filtrate in the circulation tank 12. The above-mentioned concentration of the circulating filtrate is carried out in reaction tank 3.
Using the heat of neutralization of phosphoric acid and ammonia, the reaction is carried out in the reaction tank, which is kept as open as possible. However, of course, the circulation tank 12 may also be used as a concentration tank, and a concentration tank may be provided in the middle of the piping 15.

According to the method of the present invention, after the wet phosphoric acid is neutralized with ammonia, the slurry containing phosphate-ammonium crystals is fractionated, the phosphate-ammonium is separated from the slurry containing the insoluble sludge portion, and the slurry is subjected to the neutralization step. Just by going around,
Ammonium phosphate (note: very little water-insoluble matter and other impurities, see Example 1) can be obtained with a high yield of about 70%. Furthermore, the sludge portion that cannot be obtained as ammonium phosphate can be recovered and used for fertilizer or other purposes, so no waste is generated and there is no risk of environmental pollution.

The present invention will be explained below with reference to Control Examples and Examples.

Control example 1 Wet phosphoric acid (analytical value P2O531,
3L S(h 0.81X, F O,51X, Ca
O, 19L Al 0.25%, Fe O, 57%
, Mg 0.21%) (7) 77 Ammonium phosphate was produced by neutralization. The slurry obtained in the reaction tank 3 is sent to the centrifugal separator 13 via the sedimentation separators 4 and 6, and the filtrate is circulated to the reaction tank 3 via the pipe 15 until the extraction rate reaches 45%. , piping 7. Heater 8 and centrifuge 9 were not operated.

When the withdrawal rate exceeds 45%, the transfer of the slurry to the centrifugal separator 13 is stopped, and the slurry that has passed through the sedimentation separator 4.6 is passed through the pipe 7 and heated from 80°C to 70°C in the heater 8.
The ammonium phosphate in the slurry was dissolved by heating to .degree. The slurry was then treated in a centrifuge 9 to separate it into an insoluble sludge and a filtrate.

Incidentally, the SS concentration in the slurry in the centrifuge 9 population is 20.7%, and the SS concentration in the filtrate after the separation is 2.55%.
Met. (Tagushi, ss1 degree means 1g of sample to 10% water.
The composition of the insoluble sludge discharged from the centrifugal separator 9 is as follows (note: all percentages are by weight).

^-N (ammonia nitrogen) nia, 85. T-Pt
Os (total phosphoric acid content): 35.7J 100K each of the filtrate separated by the centrifuge 9 as described above
g was successively evaporated and concentrated at 60 to 70°C, and crystallized stepwise (note: indicated by withdrawal rate) as in Clothing 1 described below.

The crystallized product was centrifuged to remove liquid, and then washed with water (crystallized product IKg
(100 cc of water was used), and the washing liquid was returned to the filtrate related to the above-mentioned dehydration. In the above process, insoluble sludge accumulated in the filtrate during evaporation and concentration, but the crystallization described above was continued without separating the sludge. Table 1 shows ammonium phosphate for each extraction rate obtained as described above.

Control Example 2 When the withdrawal rate exceeds 45%, the sedimentation separator 4.6.
20 parts by weight of water was added to 80 parts by weight of the slurry supplied to the heater 8 via piping 7 and heated to 70°C, except for dissolving ammonium phosphate in the slurry.
It was carried out in the same manner as in Control Example 1. The filtrate obtained in the centrifugal separator 9 was almost transparent.Table 2 shows the ammonium phosphate for each extraction rate obtained as described above.

Table 2 Example 1. Comparative Example 1 Ammonium phosphate was produced using the apparatus shown in the figure.

Wet phosphoric acid 20001/ the same as that produced in Control Example 1
Hr is continuously supplied to the reaction tank 3, and at the same time, ammonia gas is continuously blown into the same species to reduce NH3/H3P in the tank.
The O4%) Lt ratio was maintained at 1.0-1.3. The resulting slurry containing ammonium phosphate and insoluble sludge was continuously withdrawn to sedimentation separators 4 and 6.

The separator 6 separates the slurry into a slurry containing ammonium phosphate crystals and a slurry containing insoluble slurry, and the former is separated into ammonium phosphate and filtrate in a centrifugal separator 13, and the ammonium phosphate is diluted with a small amount of water. It was obtained by washing. The latter is maintained at 70 to 75°C via a heater 8 through a pipe 7, and is continuously supplied to a centrifuge 9 (Super Decanter 9 centrifugal effect 2000G).
The filtrate was separated into an insoluble sludge and a filtrate, and the filtrate was connected to the reaction tank 3 via the circulation tank 12 together with the filtrate from the centrifugal separator 13.

On the other hand, as a comparison, the slurry from reaction vessel 3 was not separated by sedimentation separators 4 and 6 (therefore, heater 8 and centrifugal separator 9 were not operated), and the slurry was directly passed to centrifugal separator 1.
The same procedure as in Example 1 was carried out except that ammonium phosphate was obtained in step 3 (Comparative Example 1).

Extraction rate and quality of ammonium phosphate obtained in Example 1 and Comparative Example 1 (ss and 803% by weight)
are shown in Table 3.

Table 3 Example 2 The slurry was separated into a slurry containing ammonium phosphate crystals and a slurry containing insoluble sludge using the separator 6 shown in the figure, and the same procedure as in Example 1 was performed until the former was processed to obtain ammonium phosphate. The latter was maintained at 70 to 75° C. via a heater 8 via a pipe 7, and 280 kg/hr of fishing rod was supplied from a pipe 18 before being continuously supplied to a centrifugal separator 9 at a rate of 1400 kg/hr. The appearance of the filtrate separated by centrifuge 9 was almost clear. The filtrate and the insoluble sludge separated by the centrifuge were treated in the same manner as in Example 1.

The extraction rate and quality of ammonium phosphate obtained as described above were as follows.

[Brief explanation of the drawing]

The figure shows a flow sheet of the apparatus used in the method of the invention. In the figure, l: Wet phosphoric acid supply pipe 2: Ammonia supply pipe 3: Reaction tank 4: Sedimentation separator 5 Nis slurry circulation piping 6: Sedimentation separator 8; Heater Discharge centrifugal separator lO: Sludge 12: Circulation tank 13 : Centrifugal separator 14: Product 15: Filtrate piping Continued by Tadashi Sode February 17, 1985 Commissioner of the Patent Office Manabu Shiga Tonko Indication of the case 1959 Patent Application No. 60381 2 Name of the invention Wet type Method for producing purified ammonium phosphate from phosphoric acid & Collaboration with the Ministry for amendment Patent sponsor: 3-6-32 Nakanoshima, Kita-ku, Osaka-shi, Osaka Prefecture (530)
(207) Chisso Corporation Representative Sadao Nogiζ Agent 2-8-1 Shinjuku, Shinjuku-ku, Tokyo (160) d Date of amendment order Voluntary amendment α No. of inventions increased due to amendment De Amendment Each column of "Claims" and "Detailed Description of the Invention" of the subject specification. a. Amend the statement of contents of the amendment as shown below. A. Correct the entire text of the claims as shown in the attached sheet. B9 The detailed description of the invention is corrected as follows. (1) Change “0.9~1.3” in the 4th line of page 5 to “0.9~1.3”
Corrected to 1.35 J. (2) Correct "to generate" in line 5 of the same page to "to react." (3) Insert "and insoluble sludge" after "monium crystal" on page 6, line 7. (4) Correct "centrifugation" in line 13 of the same page to "centrifugal sedimentation." (5) On the 15th line of the same page, correct "the above ■ and ■" to "the above ■ and ■". (6) Correct “liquid crystal” to “crystal” in line 16 of the same page. (7) Page 7] line, correct "centrifugation" in line 8 of page 8 to "centrifugal sedimentation". (8) K next to “Super Deka/Tar” on page 1O, line 7
Insert "two-piece product name". (9) In the third line from the bottom of the same page, after "Returned.", insert "Piping 17 is a circulation piping for slurry containing insoluble sludge, and forms a bypass similar to 5 above." OQ first negative r NH3/H3P0, molar ratio 0.9 to 1.35
Insert "Keep it in." αηIn the fourth line from the bottom of the same page, "from 60°C" is corrected to "from about 60°C before heating." 4, page 13, line 8, r'i'. 65, J to r'7.65
%,”. (2) The heading "Extraction rate" in Table 1 on page 14 and Table 2 on page 15 will be corrected to "Extraction rate". Q'l) Insert the following sentence between the 9th and 10th lines from the bottom of page 14. "The procedure was carried out in the same manner as in Control Example 1 until the extraction rate of ammonium sulfate reached 45%."
"Manufacture" should be corrected to "Use". α - Correct "inside the tank" on the 6th line of the same page to "the detection port". Insert "temperature to 60°C" next to "1.0 to 1.3" on the 7th line of the same page for α. (Incorporated Foundation) Correct "insoluble slurry" in line 12 of the same page to "insoluble sludge." (6) Insert "Note. 8 is a heater, 9 is a centrifugal separator" under "Table 3" on page 17 (outside of Note.!2). α Attached documents (full text of 'II claims) One or more attached documents (full text of claims) (1) ■ Add wet citric acid in a reactor at a reaction temperature of 50 to 80
°C, NH3/H3P0, molar ratio 0.9-1.35 K
Ammonia is reacted while maintaining the temperature, and the resulting cynic acid slurry is separated into a slurry containing the crystal portion and a slurry containing the insoluble sludge portion. ■ The slurry containing the core crystal portion is centrifuged to obtain crystals. , the liquid to be separated is returned to the reactor, and the slurry containing the insoluble sludge portion is 60 to 9
After heating to 5°C to dissolve the contained ammonium phosphate crystals, centrifugal sedimentation is performed to separate the insoluble sludge and filtrate. The liquid returned to the reactor is condensed to form a slurry containing phosphoric acid-ammonium liquid crystals, and the steps of Q to ■ described above are carried out. Method for producing ammonium acid. (2) Before centrifuging the separated slurry containing 29 parts of insoluble streaks, add 3 parts by weight of water to 100 parts by weight of the slurry.
The method according to claim 1, characterized in that 0 parts by weight or less are mixed. Procedural amendment May 23, 1985 Manabu Shiga, Director General of the Patent Office1, Indication of the case, Patent Application No. 60.381 of 19882, Title of the invention: Process for producing purified ammonium phosphate from wet phosphoric acid 3. Person making the amendment Relationship to this case Patent applicant 3-6-32 Nakanoshima, Kita-ku, Osaka-shi, Osaka (530)
(207) Chisso Corporation Representative Sadao Nogi 4, Agent 6, Number of inventions not increased by amendment 7, “Detailed description of the invention” column of the specification subject to the amendment 8, Contents of the amendment Correct the statement as follows. (1) Correct “16” in line 10 of page O to “17”. (2) Correct "17" in the third line from the bottom of the same page to "16". (3) Correct "0.4-0.3%" in the fourth line from the bottom of page 18 to "0.4-0.8%". that's all

Claims (1)

[Claims] (1) ■ Wet phosphoric acid in a reactor at a reaction temperature of 50 to 80
℃, ammonia is reacted while maintaining the NH3/H3P04 molar ratio from 0.9 to 1.35, and the resulting slurry containing phosphorus-ammonium crystals is separated into a slurry containing the crystal portion and a slurry containing the insoluble sludge portion. ,t
5) The slurry containing the crystallized crystal part is centrifuged to obtain crystals, and the liquid to be separated is returned to the reactor. After dissolving the phosphoric acid-ammonium crystals, they are separated into an insoluble sludge and a filtrate by centrifugation, and the liquid fraction #filtrate is returned to the reactor. A method for producing purified ammonium phosphate from wet phosphoric acid, which comprises concentrating the returned liquid to produce a slurry containing ammonium phosphate liquid crystals, and repeating the steps (1) to (2) above. (2) Before centrifuging the slurry containing the separated insoluble sludge portion, 30 parts by weight or less of water is mixed with 100 parts by weight of the slurry. Method described.