DE2009426A1 - Process for the production of ammonium phosphate - Google Patents

Description

Method of manufacture: of ammonium phosphate

The present invention relates to the manufacture of Fertilizers, and especially a method of fermentation from ammonium phosphates, from dicalcium phosphate or monocalcium phosphate or their mixtures as they come from na? naturally occurring rock, normally called i'hosphate rock is called, we.rden.

In the processes used to date for the production of ammonium phosphates or fertilizers containing ammonium phosphate, phosphate rock is used in normal
Temperatures treated with mineral acids such as sulfuric acid, nitric acid or hydrochloric acid, phosphoric acid and the calcium salt of the corresponding acid being formed
will. The potassium salts are more or less completely separated off from the phosphoric acid, and then with it

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ORIGINAL INSPECTED

Ca ₃ (PO ₄ ) 2 + 3 H ₂ SO ₄ Ca ₃ (PO ₄ ) 2 + 6 ENT ₃ Ca ₃ (P0 ₄ ) ₂ + 6 H (Jl 2 H ₃ PO ₄ + 3 NH ₃

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Ammonia is treated to produce the desired ammonium phosphate to manufacture.

The above-mentioned methods can be performed by the following idealized reaction equations can be described:

3 CaSO ₄ + 2H ₃ PO ₄ 3 Ca (NO ₃ ) _{2 #} + 2 H ₃ PO ₄ 3 CaCl ₂ + 2 H ₃ PO ₄ (NH ₄ ) ₂ HP0 ₄ + NH ₄ H ₂ PO ₄

The shortcomings arising from the high cost of sulfur and the technical complexity and rigidity of the process, if nitric acid and hydrochloric acid are used for the production of phosphoric acid, have been looking for alternative processes for the production of ammonium phosphates or ammonium phosphate Fertilizers.

The main disadvantage of the processes used so far is that phosphoric acid has to be produced as a necessary intermediate product between phosphate rock and ammonium phosphate, which includes the uneconomical use of mineral acid. The entire P ₂ Oc ^ir * are the phosphate rock muii converted to phosphoric acid before it is reacted with ammonia to form ammonium phosphate.

In British latent ore if a -t 316 428 a method is described duroh that this problem will be partially overcome. After that, phosphate rock is treated with sulfuric acid and ammonium sulphate, according to the Uleiohung

Ca ₅ (PO ^) ₂ + 2H ₂ SO ₄ + (NH ₄ ) ₂ SQ ₄ - »3 CaSO ₄ + 2 NH ₄ HgPO ₄

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ORIGINAL INSPECTED

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The plaster of paris resulting from the procedure can be removed and. be treated with ammonia and CO ₂ ", whereby the resulting aluminum sulfate can be used again as raw material for the process.

However, this procedure has not proven to be sufficient Proven beneficial to generally overcome the above. .

mentioned problems to be applied, possibly due to the difficulties such as insufficient recovery of P ₂ ⁰ 5 ^{in the} form of ammonium phosphate, the ■

-Rigidity in relation to different types of rock ·, ·; .- and the limitation that is that sulfuric acid. « must be used to produce ammonium phosphate. '?

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The disadvantages of so far for the production of ammonium phosphate containing fertilizers in applied processes, especially the processes that use nitric acid to produce phosphoric acid Using phosphate rock does not consist, only in the need for the production of ammonium phosphate to go over phosphoric acid, but also in that it it is impossible to produce ammonium phosphate fertilizers, which are completely free of nitrate nitrogen. They also perform all procedures except those where the calcium nitrate intermediate is reacted with ammonium sulfate becomes fertilizers in which a significant proportion of their PpO ^ content is in citrate-soluble form.

It is known. Ammonia and carbon dioxide to use To obtain nitrogen-phosphate fertilizers which contain most of the PgOt in a form soluble in nitrate ^ about a nitric acid attack on the phosphate rock and are free of calcium nitrate *. But surprisingly, none of the procedures that rely on a direct treatment of mono- or dicalcium phosphate was found with ammonia and carbon dioxide are based around nitrogen-phos-

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to obtain phat fertilizers, which contain most of the PpOc in water-soluble form, used industrially, ■ '' ■

In British Patent 299 796, the conversion of mono- or dicalcium phosphate into ammonium phosphate and described a precipitate of tricalcium phosphate using ammonia and / or ammonium carbonate, wherein but the tricalcium phosphate again into the mono- or dicalcium phosphate converted and then used again in the Eeaktion, must and if ammonium carbonate is used is the dicalcium phosphate contaminated with calcium carbonate, which can be very disadvantageous in further processing. In this case it is also preferred in the case of increased Pressure to work.

Belgian patent 369 320 describes a process for the production of ammonium phosphate from tricalcium phosphate which, in a final step, comprises a treatment with ammonium carbonate or ammonia and carbon dioxide, which, however, is carried out at high pressures, which are much higher than the simple vapor pressure of the solution. For a reaction temperature of 100 ° C
30 - 40 atmospheres indicated.

Reaction temperature of 100 C, pressures in the range of

In the French patent 753 638 is also the production of ammonium phosphate by treatment of Described dicalcium phosphate with ammonium carbonate. However, the precipitate of calcium carbonate formed is not stable under the reaction conditions and must be continuous removed in order to avoid reconversion. This conversion of available mono- and dicalcium phosphates to! Dicalcium phosphate when treated with ammonia and carbon dioxide has the yields of phosphate fertilizers 30 greatly diminished that this method for

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Production of ammonium phosphates are not applicable in practice. However, it has now been shown that "when treating appropriately prepared dicalcium phosphate or monocalcium phosphate or mixtures thereof with an aqueous solution of carbon dioxide and ammonia under set reaction conditions, a solution which contains almost all of the P ₂ Or ^from the calcium phosphates and a stable precipitate consisting essentially of calcium carbonate \ This reaction is described by the following equations:

2CaHPO ₄ + 5 NH, * + 2CO ₂ + 2H ₂ O 2CaCO ₃ + NH ₄ H ₂ PO ₄ + |

Ca (H ₂ PO ₄ ) ₂ + 2NH ₅ + CO ₂ CaOO ₅ + 2NH ₄ H ₂ PO ₄

The invention relates to a process for the production of ammonium phosphate, which is characterized in _t that firstly umseftzt calcium phosphate with a strong solution of ammonia and carbon dioxide, wherein the solution ammonia and carbon dioxide in a molar ratio in the range of 1; 1 "" to "2: 1 preferably 3: 2, and the phosphate concentration in the reaction mixture is kept below 0 <6 mol / kg water, and then separates the resulting stable precipitate of calcium carbonate.

The term calcium phosphate can mean dicalcium phosphate, monocalcium phosphate or a mixture of the two phosphates. Dicalcium phosphate, especially in frozen form, is preferred, but it can be replaced in whole or in part by monocalcium phosphate, in the latter case the phosphate concentration in the Beakttonmixture should be kept below -0.4 mol of P2O5AS water. The lower concentration of oil is also preferable if the hydrated Alöiumphösphat (ÖaHBOv, 2HgO) deprives.

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The response will be below normal. Printing carried out, i.e. below your vapor pressure of the solution at the reaction temperature,

The reaction produces a solution of ammonium phosphate and a stable precipitate of calcium carbonate alongside Ammonium carbonate,

In a preferred embodiment, ammonium phosphate is used made by adding anhydrous dicalcium phosphate a solution converts the NH * and COp in a molar ratio of 3: 2, the phosphate concentration in the reaction mixture being kept below 0.4 mol PpO ^ / kg water.

Calcium phosphates suitable for the process according to the invention can be prepared from phosphate rock by the known methods such as full or partial Reaction of phosphate rock with strong acids such as phosphoric acid, sulfuric acid, nitric acid and hydrochloric acid and then, for example, heating and post-treatment to remove the excess acid, the desired Calcium phosphate is formed. The fluorine content of the phosphate rock can be removed both before and during the manufacture of the calcium phosphate.

After separating the calcium carbonate from the invention Process products, the resulting solution can be heated to concentrate the ammonium phosphate solution and to split the ammonium carbonate into ammonia and carbon dioxide, which can be reused.

The ammonium phosphate produced according to the invention can be used in solid form by methods such as spray installation, Granulation, crystallization or atomization, or it can be done with liquid or solid fertilizers

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mixed and the resulting mixture can be granulated or are prilled »'.

The invention is explained in more detail by the following instructions, with parts always parts by weight

Example 1 '.

3.78 parts. Ga (H ₂ PO ^) ₂ . H ^ O + 13 parts IH ₄ HOO ₃ + 14 parts JSH ^ OOgNH ₂ burden- mixed with 50 parts H ₂ O, which corresponds to approximately 0.3 mol / kg H ₂ O. In the slurry h "at 25 C. The resulting slurry was the Pilterkuchen with 50 parts of H ₂ O gewasciieir and stirred for 2 h. Alifiltriert," dried at 14O ⁰ G 'was 64 /. 144 parts were received:, & blow. He enthielf 90 percent. ^ Fo OaGO * and 4.7 PPOC, corresponding to 3.1 '/ o of the originally added F ₂ Oc'"ie. 9 & | 9 ° / o of the P ₂ Oj- were as ammonium phosphate in solution. ~

Example 2 ".. V ^ - Λ ^J - \ __ / - -_ _'S: ^■■:;.. -".

6 * 88 parts GaHPO ₄ . 2H ₂ O and 13 parts NH ₄ HGO ₅ +14 parts NH ₄ GO ₂ NH ₂ were mixed with 50 files ^ H ₂ O, which corresponded to approximately 0.4 mol PgOc / kg H ₂ O «: The slurry was 64 h at Stirred at 25 ° C. The resulting sludge was filtered off, and the pIter cake was washed with 50 parts of H ₂ O and dried at 140 ⁰ O for 2 h. 4.25 parts of precipitate were obtained * It contained 92% by weight of GaCO- and 2.8% by weight of P ₂ Oc, corresponding to 4i3 ^ of the PgOc originally added. I. E. 95 »7 ^ of the P ₂ Pk; brought into solution as ammonium phosphate. The piltrate was evaporated to dryness, 4-50 parts of dry product were obtained. Hontgen analysis gave NH ₄ H ₂ PO _{4 and} small amounts (NH ₄ I

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Example 3

6.88 parts of CaHPO ₄ .2H ₂ O were heated to 175 ° C. for 72 h. The weight loss was 19 ^ 0, corresponding to a loss of 1.85 mol H ₂ O / mol CaHPO ₄ j _{>> 2H 2} O. The product was _{mixed with 13 parts Im 4} HCO ₅ + 14 parts NH ₄ CO ₂ NH _{2 and} 50 parts H ₂ O mixed, corresponding to a content of 0/4 mol P ₂ 0, - / kg H ₂ O and stirred at ^{50 ° C. for 16 h.} The resulting sludge was filtered off, the filter cake was washed with 50 parts of Y / water and ^{dried at H 0} C for 2 h. 4.09 parts of precipitate were obtained. It contained 91 wt .- ^ CaCO-. and 3.2% by weight of PpO ₁ ,, corresponding to 4, b $ of the originally added ^ p ⁰ S * that is, 95 »4 $ of the P2 ° c was in solution as ammonium phosphate.

-Patent claims-

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Claims (4)

Claims 1 · Process for the preparation of ammonium phosphate, characterized in that first Calcium phosphate, dicalcium phosphate, monocalciujjiphosphate or a mixture of these phosphates, reacts with a strong solution of ammonia and carbon dioxide, where the solution is ammonia and carbon dioxide Molar ratio in the range of 1: 1 to 2: 1 preferably 3: 2 and the phosphate concentration in the reaction mixture is kept below 0.6 mol PgOc / kg water, and then the resulting stable precipitate from CaCO, separates. 2. The method according to claim 1, characterized in that at least part of monocalcium phosphate is used, and the phosphate concentration in the reaction mixture is kept below 0.4 mol P ₂ Oc / water. 3. The method according to claim 1, characterized in that g e k e η η ζ e i c h ne t that one uses non-hydrated dicalcium phosphate and a solution that contains ammonia and Contains carbon dioxide in the molar ratio of 3: 2, and the phosphate concentration in the reaction mixture below 0.4 mol PpOc / kg water is maintained. . - 4. The method according to claim 1 to 3, characterized in that that after removal of the calcium carbonate, the solution is heated to form the ammonium phosphate to concentrate and decompose the ammonium carbonate into ammonia and carbon dioxide, which is reused can be. 6245 009839/1897