CS209434B2 - Method of making the derivatives of natural phosphates - Google Patents

Abstract

1389712 Production of solid chemical compounds PROREA 14 Nov 1972 [15 Nov 1971] 52636/72 Heading C1A A method for the manufacture of a solid chemical compound in which reactants which produce said compound are simultaneously introduced and stirred in stoichiometric quantities in a mixing device, a quantity of the compound being manufactured beforehand and in the form of a powder is introduced into the mixing device, the compound is set in motion and the reactants, including one reactant in the liquid phase, are continuously introduced to the mixing device at a rate such that there is obtained a paste mass of uniform composition containing the compound manufactured beforehand and such that when the compound resulting from the reaction which thus takes place is withdrawn as it is manufactured and when it has achieved a particle size range and distribution substantially equal to that of the compound manufactured beforehand, a quantity of the compound substantially equal to the quantity initially introduced always remains in the mixing device, the input rate of the liquid reactant being such that the compound contained in the mixing device remains permanently in solid phase. Exemplified reactions are: (1) Ca 3 (PO 4 ) 2 +H 2 SO 4 # Ca(H 2 PO 4 ) 2 (simple superphosphate). (2) H 3 PO 4 +Ca(OH) 2 # CaHPO 4 .2H 2 O (bicalcium phosphate) which may be dried in suspension in hot air. (3) H 3 PO 4 +NH 3 (g) # NH 4 H 2 PO 4 Grain size of solid reactant may be same as that of product. The mixer may be heated or cooled.

Description

(54) Method for producing natural phosphate derivatives,

The invention relates to a process for the preparation of natural phosphate derivatives.

It is known that the preparation of some compounds both in the laboratory and on an industrial scale encounters a number of difficulties, since the chemical reactions with which these compounds are obtained are difficult to perform due to some of the properties of these compounds, which are intrinsic in nature.

Particular mention may be made of reactions at increased velocity which yield a yield of about 100% and result in the final product in solid form. The reactants used in such processes may be liquid, solid or gaseous and, in a given reaction, the reactants may be used individually in any of these three states.

One of the difficulties associated with the above reactions is that it becomes practically impossible to produce a rapidly homogeneous mixture and to carry out a complete reaction quickly, which entails a significant reduction in the quality of the product thus obtained, since the reaction is not complete. Precautions should be taken to store the product in the halls in order to allow the reaction to continue as much as possible.

Another disadvantage stems from the fact that the power consumed by various devices such as kneaders, blenders or other machines in which these reactions are carried out is relatively high, which greatly increases the final cost of production. In addition, some reactions are associated with a constant risk of clogging and / or clogging of these devices, resulting in a halt to the entire manufacturing process.

For example, in a particular case of industrial phosphate production, such as simple superphosphate, weakly dilute sulfuric acid and sodium tertiary phosphate are reacted in a mixer. In a very short time, a dense, heterogeneous paste is obtained, which, due to the power consumed by the mixing device, must be quickly discharged into a tank or "pit", where the reaction proceeds more slowly than in the mixing device. The product remains in this tank for about an hour until it completely solidifies, after which it is ground and then stored in the halls for at least one month before bagging. It should be noted that the stored product still contains unreacted acid and a storage time of approximately one to two months to achieve 95-98% reaction should be provided, as well as packaging well resistant to the effects of phosphoric acid, which arises.

The same circumstances and difficulties may occur209434

---------- In the production of triple superphosphate, secondary and primary calcium phosphate for animal nutrition and for the production of ammonium phosphates and others.

In order to improve the manufacturing process for the production of secondary calcium phosphate, a process in which concentrated acid has been proposed has already been proposed. Phosphorous let's drip onto calcium carbonate. To improve the reaction, the resulting product can be continuously recycled to the reaction zone at a rate of 0.5 to 1 part by weight per 1 part by weight of lime.

Secondary production was also proposed. calcium phosphate by reacting concentrated phosphoric acid with lime, wherein part of the finished product is optionally mixed with lime in a ratio of 0.5 to 1 part by weight per 1 part by weight of lime.

The above-mentioned difficulties and disadvantages can be overcome by the process according to the invention, which makes it possible to obtain in a very short time in practically 100 ° / o the yield of chemical compounds such as derivatives of natural phosphates, and · very reliable.

Accordingly, the present invention provides a process for the preparation of derivatives of natural phosphates, in particular simple superphosphate, secondary calcium phosphate and primary ammonium phosphate, in which stoichiometric calcium phosphate and sulfuric acid or lime and acid are introduced and mixed in stoichiometric quantities as starting materials. phosphoric acid or ammonia and phosphoric acid, depending on the resultant product to be produced and then. the resulting 'reaction product' removes · to the same extent; in which it arises; which method is characterized in that the preformed product is first introduced into the mixing device, whereupon the product is mixed with continuously supplied starting materials, and is still maintained in the mixing device. the product being produced in an amount equal to that of the pre-loaded product, wherein the solid starting levers are fed in powder form having the same granular thermometric composition as the fed product, while the liquid starting materials are fed in such a quantity per unit of time that the product contained in the mixer remains permanently in 'solid' form.

It should be noted that, in addition to the advantages mentioned above, the process according to the invention ensures that the finished product can be used immediately, thereby eliminating both the need for product storage and the use of special packaging made from a material resistant to unreacted reactants.

The process according to the invention further allows the use of the reactants in maximum concentration, which implies that the finished product has a minimum moisture content, even zero, so that it is possible to dispense with the costly drying equipment occupied by the process. often a considerable floor area or at least substantially reduce the cost of drying the product.

A further advantage of the process according to the invention results from the fact that machines, such as kneaders, mixers or other devices in which the process according to the invention is carried out, consume only a minimal amount of energy and therefore do not present a permanent risk of clogging. if necessary clogging.

The above-mentioned essential advantages definitely contribute to obtaining a finished product which, in addition to the above-mentioned characteristics, has minimal production costs.

The following is a few examples of embodiments of the process of the invention describing the production of a primary calcium phosphate; of a simple superphosphate and a primary ammonium phosphate, but to which the process according to the invention is not limited in any way.

Example 1 and 1

Simple superphosphate

It is known to produce a simple superphosphate, to allow sulfuric acid to act on the tertiary calcium phosphate according to the reaction.

Ca3 (PO4) 2 · + 2H2SO4 = Ca (H2PO4) 2 + + 2 Ca2SO4 In the process according to the invention, a preformed simple superphosphate having a grain size corresponding to 20% of the residue on the sieve with holes is first introduced into a 3000 liter mixer. diameter 0.147 mm; After the mixer has been put into operation, both sulfuric acid at a concentration of 98.50% at a rate of 4730 kg / h and calcium tertiary phosphate at a grain size of 10 to 20% are simultaneously and continuously supplied. sieve residue with holes of diameter · 0.147 mm · at '6600' kg / h. The simple superphosphate thus obtained is continuously removed from the mixer by suitable equipment, but at the same time it can maintain in the mixer the necessary amount of powdered substance to ensure thorough mixing and rapid dispersion of the reactants.

In this way, a simple superphosphate having a grain size corresponding to 10 to 20% of the sieve residue with 10,000 kg / h diameter apertures of 10,000 kg / h is obtained, the moisture content of which is practically zero.

The advantage of this method is that a dry product is obtained in the form of a low-fluorine powder, at a conversion rate practically equal to 100%.

Example 2

Secondary calcium phosphate of cattle nutrient grade г

Treatment of slaked lime according to the reaction scheme with liquid phosphoric acid with 50-54% of pre-fluorinated P2O5

H3PO4 4- Ca (OH) 2 -> CaHPOd. 2 H 2 O yields a secondary calcium phosphate dihydrate.

It is necessary not to raise the temperature above a certain value during this reaction in order not to get rid of the crystalline water. The temperature is maintained at the desired level by cooling using a circulating water jacket. Subsequent low temperature drying allows the water content to be reduced to approximately 1%.

A pre-manufactured secondary calcium phosphate having a grain size corresponding to 20% of the residue on a sieve with 0.147 mm diameter holes is pre-loaded into a 3000 liter mixer.

After the mixer was started, both phosphoric acid at a concentration of 50-54% P2O5 at 4100 kg / h and slaked lime at 2440 kg / h were simultaneously and continuously fed. Secondary calcium phosphate, obtained in an amount of 5500 kg / / h, particle size corresponding 2O0 / ₀ residue on the sieve with openings of 0.147 mm and a maximum moisture content of about 15%. It is obtained in the form of a very fine powder which is easily dried by a stream of warm air of suitable temperature.

In the same manner, a secondary sodium phosphate of the kind suitable for human nutrition can be produced from phosphoric acid prepared by a thermal process.

Example 3

Primary ammonium phosphate

By treating phosphoric acid with anhydrous ammonia according to the reaction scheme

H 3 PO 4 4- NH 3 = NH 4 H 2 PO 4 yields primary ammonium phosphate.

Reaction heat allows removal and recovery of the dry product.

A pre-manufactured primary ammonium phosphate of a grain size corresponding to

Claims (1)

SUBJECT A process for the preparation of derivatives of natural phosphates, in particular simple superphosphate, secondary calcium phosphate, primary ammonium phosphate, in which stoichiometric calcium phosphate and sulfuric acid or lime and phosphoric acid or ammonia and phosphoric acid are introduced and mixed into the mixing apparatus in stoichiometric quantities as starting materials, characterized in that a pre-fabricated for the remainder of 20% on a sieve with 0.147 mm diameter holes is first introduced into the mixing device. After the mixer was started, both phosphoric acid at a concentration of 50-54% P2O5 at 22,800 kg / h and anhydrous ammonia at 2960 kg / h were simultaneously and continuously fed. The primary ammonium phosphate obtained has a grain size corresponding to 200/0 of a residue on a sieve with 0.147 mm diameter sieve and its production is 20,000 kg / h. As in the production of superphosphate, the yield of this reaction is 100%, the losses of ammonia are virtually zero, since this reactant is fed to the mixer from below to avoid losses. With regard to the rate of introduction of the reactants, it is predetermined to the properties of the apparatus used; when using a mixer, this rate is less than the time required to produce a perfect blend, thereby ensuring that the mixed product is kept in the solid phase in the mixer. Moreover, the mixing time itself is of course conditioned by the existing thermal regime in individual cases, i.e. the endothermic or exothermic nature of the reaction taking place in the mixer. The mixer may therefore preferably be provided with a heating or cooling device adapted to be used for all kinds of reactions. In this way, the heating device makes it possible to remove moisture from the reaction product and thereby obtain a dry product at the outlet of the device. On the other hand, the cooling device allows to dissipate excess heat, which could possibly deteriorate the quality of the product by raising the internal temperature to a value higher than that at which the product decomposes. The process according to the invention can be used particularly advantageously in the production of alkaline phosphates, alkaline earth metal phosphates, used in particular as fertilizers or as supplementary nutrients for animals, magnesium phosphates and the like. While the method just described seems to be most suitable for carrying out the invention under special technical conditions, it is understood that it may be varied in various ways without departing from the scope of the invention, or some of its parameters may be replaced by others that provide the same technical function. the product is mixed with the continuously supplied starting materials and the product is still maintained in the mixer in an amount equal to the amount of the pre-introduced product, the solid starting materials being supplied in powder form having the same granulometric composition as the pre-introduced product. the liquid starting materials are fed in an amount ensuring the solid form of the product in the mixer.