DE292530C

DE292530C -

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Publication number: DE292530C
Application number: DENDAT292530D
Authority: DE

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KAISERLICHESIMPERIAL

PATENTAMT,-PATENT OFFICE, -

Es gibt theoretisch drei verschiedene Ammoniumsalze der Phosphorsäure, von denen aber nur das primäre Salz NH₁H₂PO₄ beständig ist, während die beiden anderen sich unter Abgäbe von Ammoniak allmählich in das einbasische Salz verwandeln.There are theoretically three different ammonium salts of phosphoric acid, of which only the primary salt NH ₁ H ₂ PO _{4 is} stable, while the other two gradually transform into the monobasic salt with the release of ammonia.

Die Herstellung von phosphorsaurem Ammoniak findet bisher in sehr geringem Umfange statt. Die naheliegende Verwendung desselbenThe production of phosphoric acid ammonia has so far been carried out on a very small scale instead of. The obvious use of the same

ίο als ein höchstkonzentriertes Düngemittel ist an seinem hohen Preise gescheitert; es findet bisher nur Verwendung zum Feuersichermachen brennbarer Stoffe usw. Durch die Herstellung dieses Produktes an den Produktionsstätten des Ammoniaks kann sein Preis, wie im folgenden des näheren dargelegt wird, ganz bedeutend reduziert werden, es fehlte aber noch an einem brauchbaren Fabrikations verfahren. Das bisherige Verfahren der rein empirischen Absätti- gung der Phosphorsäure mittels Ammoniakgas oder auch Ammoniakwasser ist für einen kontinuierlichen Betrieb unbrauchbar, es ist auch unrationell, weil das erzielte Produkt Ammoniakverluste erleidet, und vor allem, weil eine Ab-Scheidung des Salzes in heißer konzentrierter Lösung nicht stattfindet, sondern hierzu die gesättigte Lösung erst zum Erkalten gebracht werden muß.ίο as a highly concentrated fertilizer is on failed its high prices; so far it has only been used to make flammable fires safe Substances etc. Through the manufacture of this product at the ammonia production facilities its price can be reduced quite significantly, as will be explained in more detail below but a usable manufacturing process was still lacking. The previous method of purely empirical saturation supply of phosphoric acid by means of ammonia gas or ammonia water is for a continuous Operation unusable, it is also inefficient because the product obtained loses ammonia suffers, and mainly because a separation of the salt in hotter concentrated Solution does not take place, but for this the saturated solution is first brought to cool must become.

Man verfährt bisher einfach in der Weise, daß man eine unbestimmte Menge Phosphorsäure mit Ammoniak neutralisiert, bis die heiße gesättigte Lösung beim Erkalten zu einer Kristallmasse erstarrt. Da man nicht wußte, daß der Grad der Absättigung eine große Rolle auf den Prozeß ausübt, so hat man auch keinen Wert darauf gelegt und es vollständig dem Zufall überlassen, wie weit die Absättigung getrieben wurde.So far, the simple procedure is that an indefinite amount of phosphoric acid is used neutralized with ammonia until the hot saturated solution turns into a crystal mass on cooling stiffens. Not knowing that the degree of saturation played a major role Process, no value was attached to it and it was entirely a matter of chance up to how far the saturation was taken.

Der bisherige Prozeß ist naturgemäß ein periodischer. Sobald ein Bad gesättigt ist, muß es abgelassen und wieder mit neuen Mengen Phosphorsäure beschickt werden.The previous process is of course a periodic one. Once a bath is saturated, it must it can be drained and refilled with new amounts of phosphoric acid.

Es hat sich nun gezeigt, daß Lösungen, deren Absättigung mit Ammoniak so weit getrieben worden war, daß sie größere Mengen zweibasi- +5 sehen phosphorsauren Ammoniaks enthielten, selbst beim Erkalten, geschweige denn in der Hitze, keine oder nur eine unbedeutende Neigung zum Kristallisieren haben. Der Grund hierfür liegt in der Eigenschaft des zweibasischen phosphor sauren Ammoniaks, nicht nur selbst nicht zu kristallisieren, sondern auch die Kristallisation des an sich sehr leicht und sehr schön kristallisierenden einbasischen Salzes zu verhindern. .It has now been shown that solutions whose saturation with ammonia is carried so far had been that they had larger amounts dibasic +5 see phosphoric acid ammonia contained, even when cooling, let alone in the Heat, have little or no tendency to crystallize. The reason this lies in the property of the dibasic phosphoric acid ammonia, not just itself not to crystallize, but also the crystallization of the in itself very easy and very beautiful to prevent crystallizing monobasic salt. .

In Gemäßheit der vorliegenden Erfindung werden alle diese Schwierigkeiten umgangen und ein haltbares Ammoniumphosphat in kontinuierlichem Verfahren dadurch ermöglicht, daß man Phosphorsäure in kontinuierlichem Strome der bereits mit Ammoniak übersättigten Lauge zufließen läßt. Hierdurch wird eine momentane Ausscheidung des einbasischen Ammoniumphosphates in kristallinischer Form erzielt.In accordance with the present invention, all of these difficulties are circumvented and a durable ammonium phosphate made possible in a continuous process by the fact that Phosphoric acid flow in a continuous stream of the liquor already supersaturated with ammonia leaves. This causes a momentary excretion of the monobasic ammonium phosphate obtained in crystalline form.

Die Ausführung des Verfahrens erfolgt auf folgende Weise. In einen Ammoniakabsorptionsapparat, wie sie in allgemeiner Verwendung · sind, läßt man Phosphorsäure einfließen, während gleichzeitig Ammoniakgas oder -wasser durchströmt. Die Absättigung darf nur so weit getrieben werden, bis die Bildung des zweibasischen phosphorsauren Ammoniaks soebenThe procedure is carried out in the following manner. In an ammonia absorber, as they are in general use, phosphoric acid is allowed to flow in while ammonia gas or water flows through at the same time. The saturation is only allowed so far be driven until the formation of the dibasic phosphoric acid ammonia has just occurred

Claims

has taken place, so there is a guarantee that all free phosphoric acid at least has been converted into monobasic salt, which is contrary to the alkaline reaction Methyl orange can be seen.

The lye thus obtained, which is to a certain extent already oversaturated, contains phosphoric acid allowed to flow in a continuous stream, and it works in the places where it is

ίο mixed with the lye, a regression of the polybasic salt into the monobasic. This formation takes place momentarily and safely while they operate periodically when ammonia is introduced into phosphoric acid until it is saturated would just happen randomly.

With a suitable concentration of the solution, that depends on the concentration of the applied Depending on phosphoric acid, the monobasic phosphoric acid ammonia separates into fine ones Crystals and is removed and washed in a known manner from the bath.

Letting the phosphoric acid flow in continuously prevents it from becoming too form large amounts of dibasic salt which interfere with crystallization. The regulation of the The inflow of phosphoric acid can easily be achieved given constant amounts of ammonia set in such a way that operation can take place continuously and without any crystallization disturbance.

Scheele and Car o have asserted that the production of phosphoric acid ammonia is only possible if the phosphoric acid used contains a larger percentage of free sulfuric acid. In this assertion lies the evidence that they failed to see the essence of the process. They saturate until the acidic reaction of the sulfuric acid has disappeared. At this point in time, however, the formation of the monobasic phosphoric acid ammonia has also taken place. The addition of sulfuric acid unconsciously serves as a gauge for saturation, so it is not necessary at all, rather harmful because it contaminates the product obtained and is used for certain purposes, e.g. B. in silk dyeing, wood impregnation, etc. makes it downright useless. By using phosphoric acid instead of sulfuric acid for the absorption of the ammonia, a tremendous economic advantage is achieved, especially when the phosphoric acid ammonia obtained is used as a fertilizer. It is then called upon to replace the mixtures of sulfuric acid ammonia with superphosphate, the so-called ammonia superphosphates. It is a known fact that, with suitable precautionary measures and the application of specific types of rock phosphate, no more, even mostly less, sulfuric acid is needed for the extraction of phosphoric acid than if the same rock phosphates are processed on superphosphate. So if you use phosphoric acid to absorb the ammonia, you don't need sulfuric acid, so you save yourself the expense of it. There is probably no need to point out that enormous savings can be made in transportation, wages and other expenses.

P Λ T E N T - A N S P E U C H :P Λ T E N T - A N S P E U C H:

Process for the production of phosphoric acid ammonia, characterized in that that in the saturated, already dibasic ammonium phosphate-containing liquor Phosphoric acid is added, allowing it to flow continuously, so that a small amount of dibasic Ammonium phosphate remains present in the lye, so that the primary salt is precipitated and can be removed continuously.