FORM 2
THE PATENT ACT, 1970

(39 OF 1970)
AND
PROVISIONAL/SPECIFICATION (See section 10, rule 13)

1. TITLE OF THE INVENTION Process For INDUSTRIALLY PRODUCING PURIFIED
AMMONIUM PHOSPHATE (100% WATER SOLUBLE) FROM IMPURE WET
PROCESS
2. APPLICANT(S)
PHOSPHORIC ACID ( 26-28% P205)
(a)Name: MR R.K.JAIN ,MR K.L.DHATIA , MR.B.NAGARAJ ,MR M.BASU,MR,E.KATHAL
(b) Nationality: INDIAN INDIAN INDIAN INDIAN INDIAN
(c) Address: RCF RCF RCF RCF RCF
3. PREAMBLE TO THE DESCRIPTION

PROVISIONAL
The following specification describes the invention.

COMPLETE
The following specification particularly describes the invention and the manner La which it is to be performed.

4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims' should start with, the
preamble—"1/We claim" on separate page)

6. DATE AND SIGNATURE (to be given at the end of last page of specification)
7. ABSTRACT OF THE INVENTION (to be given alongwith complete specification on
separate page)
Note.—
*Repeat boxes in case of more than one entry.
*To be signed by the applicant(s) or by authorised registered patent agent.
•Name of the applicant should be given in full family name in the beginning.
•Complete address of the applicant should be given stating the postal index no./codg State and country.
"Strike out the column which is/are not applicable.
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Process for Producing Purified Mono Ammonium Phosphate (100% Water Soluble) from Impure Wet Process Phosphoric acid (26-28% P205)
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for producing purified Monoammonium Phosphate from wet process phosphoric acid. More particularly it relates to a process for producing industrially usable Ammonium Phosphate directly from wet process phosphoric acid with a high yield.
2. Description of the Prior Art
Monoammonium phosphate obtained by reacting ammonia with wet process phosphoric acid contains a large amount of impurities originated from the impure phosphoric acid; hence it can be used as fertilizers, but cannot be used for industrial uses, as it is. For producing industrial purified Monoammonium phosphate from wet process phosphoric acid, it is necessary to purify the phosphoric acid in advance according to a process of extracting phosphoric acid from wet process phosphoric acid according to solvent process, followed by reacting ammonia with the resulting extract to obtain Monoammonium phosphate containing a small amount of impurties.
However, this extraction process cannot be regarded as an industrially advantageous process due to its complicated steps. On the other hand, as to various compounds stepwise formed by the reaction of wet process phosphoric acid with ammonia, "Studies on Chemical fertilizers" (written by Ando and Akiyama, issued as a reprint on May 20, 1976, from Nissin Syuppan K.K.) has suggested for the present a possibility of producing industrial ammonium phosphate from a mother liquor of ammonium phosphate obtained by neutralizing wet process phosphoric acid with ammonia under certain neutralization conditions to form (FeAI)NH4 H2 (P04)2.1/2H2 O or (FeAI)NH4 HF( P04) 2 to thereby obtain the mother liquor of ammonium phosphate having Fe, Al and F contained in wet process phosphoric acid removed therefrom. However, this process also has a drawback that it requires (dilution ) such prolonged steps as stepwise pH control, filtration step and crystallization step, which results in increase of energy consumption.
The yield of ammonium phosphate based on phosphoric acid in the above description is defined as "percentage recovery" as follows:
As described above, when wet process phosphoric acid is directly neutralized, the yield of purified ammonium phosphate based on phosphoric acid is considerably low.
In view of the above problems of the prior art, the present inventors have made extensive research in order to find a process for producing monoammonium phosphate with a high yield i.e. a high percentage recovery by direct neutralization of wet process phosphoric acid.
As a result, we have found that when wet process phosphoric acid and ammonia are reacted at 80-90° C. while the pH of the solution is between 4.0-4.5, followed by separating the resulting slurry containing monoammonium phosphate crystals and an insoluble sludge. The slurry according to a conventional process is concentrated to recover monoammonium phosphate followed by centrifugal separation to get MAP with a high yield.
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As is apparent from the above description, an object of the present invention is to provide a process for obtaining monoammonium phosphate from wet process phosphoric acid with a high yield. Another object of the present invention is to provide monoammonium phosphate produced according to the above process.
Claims: 1.A Process for producing 100% Water Soluble Mono Ammonium Phosphate (abbreviated as MAP)
From Wet Process Phosphoric acid the steps are as follows :
1.a Reacting ammonia with impure wet process Phosphoric acid in a reactor maintaining the temperature at 80-90° C and further diluting the slurry with water in molar ratio between 1-1.10 to form a slurry comprising of MAP, soluble impurity and an insoluble sludge.
b. Separating the resulting slurry containing MAP and insoluble sludge on a specially
designed filter system.
c. Concentrating the filtered liquid (fractional crystallization), and further centrifuged to
get the purified crystals of MAP.
2. Separation of Ammonium Sulphate crystals (abbreviated as AS ) :-
Filtrate from centrifuge containing M.A.P., AS and sludge formed will be utilised in the existing NPK complex Fertilser as a Nitrogen & Phosphorus nutrient source. Thus it helps in achieving a total recycle and reuse of valuable NP nutrients making it a cost effective, zero effluent system.
BACKGROUND OF INVENTION
1. Field of the invention
This invention is to produce purified MAP from Impure Wet process Phosphoric acid. More particularly it is a specific process producing 100% Water soluble Fertiliser from Impure wet process phosphoric acid (26 - 28% P2O5) (abbreviated as PA).
2. Description of the Prior Art:
MAP obtained by reacting ammonia with impure PA contains a large amount impurities originated from rock phosphate. It can be used in the preparation of complex fertilizer or as a fertiliser, but it has limitation in using as a 100% water soluble fertilizer due to these inherent carried over impurities.
PA purification can be done by solvent extraction but due to cumbersome unit operations involved in it, it is not economically viable.
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During neutralization of PA with ammonia under certain specific conditions helps to precipitate the impurities of Iron, Aluminum, Silica Ca, Mg, Na, K, F, Si, & S04 as FeAINH4(P04)2, FeAINH4HF(P04)2 to thereby obtain the mother liquor of Ammonium phosphate and MAP . This process requires a prolonged filtration time & sufficient area for filtration due to the gelatinous nature of the precipitate
In view of the above problem of the prior act, the present invention have made extensive research in order to find a process to remove almost all impurities from slurry containing MAP crystals, and concentrating the resulting filtrate to recover pure MAP. The Fertiliser used in Drip/ Foliar application needs 100% water solubility.
As it is apparent from the above description, the object of the present invention is to provide a process for obtaining 100% water soluble MAP.
Summary of the invention
The present invention has a
1) Main constitution
2) Embodiment as follows
1.A Process for producing purified 100% Water Soluble MAP from Phosphoric acid comprises:-
Step 1. Reacting ammonia with PA in a reactor while keeping the reaction temperature between 80-90 °C. Diluting the solution with water in a certain molar ratio.
Step2. Separating the slurry at pH 4.0 - 4.5, in a filter unit at temp.~60°C.
Step3. The separated filtrate from step 2 is concentrated, crystallized & centrifuged to yield pure MAP.
Step4. Separated sludge from step 2 and Centrifuged liquid from step 3
containing some part of MAP & AS are used as Nitrogen & Phosphorus inputs in existing NPK fertilizer production.
Detail description of the preferred embodiments
The constitution and effectiveness of the present invention will be described below in more detail
The wet process PA acid in the present invention refers to the so called wet PA obtained by Hemi hydrate Process treating rock phosphate with a mineral acid & Vapor ammonia. The essential specific features of the process of the present invention concerns following three points.
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1. Ammonia is continuously fed into a wet process PA at temp.80 -90°C and molar ratio1-1.01, there forms a slurry containing both MAP crystal and an insoluble sludge.
2. The above slurry is separated at ~60°C on a specially made filter system.
3. The filtrate on concentration, crystallization & filtration yields purified MAP crystals.
By employing the above procedure, separation and removal of the sludge as impurities are efficiently carried out and as result, the yield of MAP is substantially raised.
The process of the present invention will be described below, referring to the accompanying drawing.
As given in enclosed FIG. 1, PA (Sp. Gr. 1.26 - 1.28) and ammonia are fed into a reaction vessel wherein neutralization reaction is carried out till the pH of the solution is between 4.0 - 4.5 The reaction temperature is preferably in the range of 80 - 90°C. If they are reacted at temperatures lower than 60.degree. C, precipitation of the MAP salt along with impurities takes place, while if reacted at temperatures exceeding 90°C, temperature maintenance cost is required; hence both the reactions at temperatures outside the range are not advisable / economical. Further, outside the above temperature range, deposition and clogging of MAP along with impurities are likely to occur at bottom and other service parts of the reaction vessel.Through the above neutralization reaction, an MAP slurry as a reaction mixture is formed in the reaction vessel. On dilution of the Ammoniated slurry (Sp. Gr. 1.22 - 1.24) the temperature comes down to ~ 60°C. This slurry consists of MAP mother liquor and an insoluble sludge as an aggregate of insoluble impurities. This MAP slurry is continuously or intermittently sent to Filteration unit where the slurry is separated into a slurry containing MAP in a larger ammount and the insoluble sludge. The filtrate is sent to the concentration unit where it is concentrated ( Sp. Gr. 1.32 - 1.35) The concentrated slurry is cooled to 35°C and is sent to Centrifuge for separation of MAP and the filtrate, the MAP being washed with a small amount of water to recover it as product, and the filtrate being sent to a NP section for its use in the preparation of Complex Fertiliser.
The sludge thus obtained still contains a considarable amount of Phosphatic salts matters as byproduct, it is also used as input in the preparation of the Complex fertilizer. The filtrate obtained from the centrifugal separator is also sent to NP section of the complex Fertiliser as input.
In the above concentration unit, the circulating filtrate may be carried out by utilizing the neutralization heat of phosphoric acid and ammonia in the reaction vessel. The circulation vessel may be at the same time employed as the concentration vessel.
According to the process of the present invention, after the neutralization of phosphoric acid with ammonia, the slurry is separated containing monoammoium phosphate solution and the insoluble sludge part. The filtrate is sent to evaporation section, after concentration the slurry is cooled. It contains monoammonium phosphate (a product having an extremely low content of water-insolubles and other impurities, see Example 1) with a yield as high as about 60%. Further, it is also possible to recover the sludge part
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which cannot be obtained as monoammonium phosphate and can be utilize it as fertilizer or in other applications; thus no waste occurs with zero effluent without environmental pollution.
By employing the above procedure separation and removal of the impurities as sludge are effectively removed out. The process of the present invention has been described with the Batch data (3nos), Typical Analysis along with the accompanying drawing.

Sr.No. Contents Batch 1 Batch II Batch III
A PHOSPHORIC ACID ( % P205)
Specific Gravity 1.260 1.200 1.27
ii Weight (Kgs) 88.0 200.0 80.0
iii Volume (Ltrs) 73.5 170.0 65.0
B. Ammonia Gas consumed (Kgs) 6.0 12.0 5.7
C. Water For Dilution (Kgs) 88.0 200.0 80.0
D. Specific Gravity of Slurry After Dilution 1.17 1.12 1.14
E. Pressure of Star Filter (Kgs/cm2) 0.20 0.20 0.20
F. Specific Gravity of Clear Solution 1.13 1.06 1.11
G. Quantity taken for Concentration (Ltrs) 100 320 100
H. Sp. Gravity of Final slurry 1.32 1.33 1.32
I. Weight of slurry taken for Filtration (Kgs) 6.5 30.0 6.0
J. Wt. of water for washing crystals (Gms) 200 1200 200
K. Wt. of Dry MAP crystals (Kgs) 4.0 12.0 3.7
L. Recovery as MAP (%) 57.0 60.0 63.0
TYPICAL ANALYSIS REPORT
Table No. -I

CONSTITUENTS MAP (Percent) REJECT -I (Sludge)
ON DRY BASIS
(Percent) REJECT - II (Filtrate)
ON DRY BASIS
(Percent)
Total P205 61.27 30.26 42.49
Water Soluble P205 61.15 — 42.31
Ammoniacal Nitrogen 12.55 — 13.90
AI2O3 NT 0.07 NT
Fe203 123 PPM 5.17 214 PPM
CaO — 8.18 NT
Si02 NT 1.07 NT
S04 1.72 3.30 7.89
F — 2.23 —
Moisture 0.50 — 1.15
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Conclusions :
1) 100% water soluble Mono Ammonium Phosphate having grade (NPK) 12:61:0 can be produced by above mentioned process.
2) The yield as dry MAP product, is around 60 %.
3) The sludge, and the final filtrate after separating MAP crystals are rich in plant nutrients, like P2O5 and Ammonical nitrogen, hence can be utilized in our existing complex fertilizer NPK 15:15:15 Plant.
BLOCK DIAGRAM FOR PREPARATION OF WATER SOLUBLE MONOAMMONIUM PHOSPHATE. FIGURE -1

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