DE2748220A1 - PROCESS FOR GRANULATING KALI SALT - Google Patents

Description

HOPPMANN · BITLB «& PARTNER

DR. ING. E. HOFFMANN (WM-VKl · DIPL-ING. W-EITlE · 01. «EI. NAT. K. HOFFMANN . DIPl.-ING. W. IEHN

01PU-IN O. K. FOCHSLE - D *. REt. NAT. ·. HANSEN ARABEI LOAD CUP 4 (STERNHAUS) · DO * t MÖNCHEN ·! · TELEPHONE (·· ») 9IW87 · TELEX 05-2MIf (PATHE)

29 841 o / wa

INTERNATiaiAL MINERALS ft CHEMICAL CORPORATION, TERRE HAUTE, INDIANA / USA

Process for granulating potash salts

The invention relates to the granulation of potash salts. It relates in particular to the granulation of potash salts by incorporating a binder prior to the granulation step. .

Potash salts do not easily form large crystals or particles, but they are increasingly being used in compound fertilizers Used to avoid segregation. Particles in the desired

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The size area must also be firm enough to hold during the To be able to withstand degradation in treatment and mixing stages. Potassium salts resist due to the lack of plasticity granulation in conventional rotating drums or trough granulating devices. Granules produced in such devices have no resistance to disintegration on drying and the yields of granules in the desired Size range from 3.3 χ 1.2 mm (6 χ 14 mesh Tylor sieve), is low and is often on the order of 10%. As a result, a large part has to be recycled and this causes enormous production costs.

There is therefore a need for a method of granulating potash salts that has the desired degree of granulation results in high yields and in which granules are obtained which have good dimensional stability during handling Storage and use.

It is an object of the invention to provide a method for granulating potash salts.

It is another object of the invention to provide a method of granulating of potassium salts by adding a binder.

Another aim is to be seen in a composition of a potassium salt and a binder in granulated form to show.

Other objects will become apparent to those skilled in the art from the description below.

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The invention relates to a method for granulating potash salts with the formation of high yields of granules in the desired particle size by adding the potash salt with an inorganic Phosphatsalζ as a binder and water mixed, the mixture granulates and dries.

In the process according to the invention, the potash salt is with the Phosphate binders in a ratio of about 15-150 kg (1.5 to 15%), preferably about 50-150 kg (5 to 15%) Binder / t crystals mixed. The amount required is variable and depends on the binder selected and the material to be granulated. Water is added either before or after the potash salt is mixed with the binder in an amount of 75 to 200 l / t of the mixture (7.5 to 20%), the exact amount depending on the moisture content, the type and particle size of the potash salt and binder used during the process depends. The mixing is carried out in conventional drum or pan granulating devices and additional water can be added as needed to maximize the formation of the preferred granule sizes be admitted. The preferred water content is from about 10 to about 15 percent. Then the mixture is a usual dryer supplied.

Potash salts, which can be granulated according to the invention, are, for example, without hereby expressing any limitation, potassium chloride, potassium carbonate, potassium sulfate, Potassium nitrate, langbeinite and mixtures thereof.

Suitable binders include monoammonium phosphate, diammonium phosphate, Mono- or disodium phosphate, mono- or

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Dipotassium phosphate and mixtures thereof. Also dibasic Magnesium sulfate is suitable as a binder. All of these compounds are known and most are commercially available. The products that are commercially available are also suitable for practicing the invention as such.

A preferred binder is monoammonium phosphate, which can be suitably prepared at the time of application. A particularly preferred binder is a mixture from mono- and diammonium phosphate, which is obtained by reacting ammonia with phosphoric acid in a molar ratio from about 1.1-1.5: 1. Mono- or diammonium phosphate or a mixture thereof can be prepared in situ by a potassium salt is premixed with a suitable amount of phosphoric acid and the mixture is then placed in an ammunition granulator, for example a TVA rotary drum granulator like him in U.S. Patents 2,729,554 and 2,741,545, treated with ammonia. A preferred source for Phosphoric acid is the product that is obtained after the wet process because it contains a small amount of iron, aluminum and contains other metallic impurities, which increase the strength of the potash salt granules. Becomes monoammonium phosphate Formed in situ, water is preferably added to the potassium salt prior to the addition of the phosphoric acid. The ammonization step can preferably be carried out with anhydrous ammonia, but aqueous ammonia can also be used Ammonia can be used if desired. In this case, the amount of water should be with the aqueous ammonia must be taken into account when adding more water for the granulation stage.

If magnesium phosphate is used as a binder, this can

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can be easily formed in situ during the granulation step. The magnesium becomes the potash salt as an oxide, Hydroxide or carbonate is added and phosphoric acid - preferably phosphoric acid produced by the wet process - is sprayed onto the mixture. The magnesium compound and Phosphoric acids are used in a molar ratio of generally between 0.5-1.5: 1, preferably 1: 1.

If Langbeinit (K-SO ^ 2MgSO-) is granulated, it is preferably in a form in which it contains at least 20% granules with a particle size of -2OO meshes (Tyler) and a minimum amount of +30 mesh (Tyler) granules, preferably less than 5%.

Another embodiment of the invention can be seen in the fact that the granulation of potash salts other than Langbeinite Can be improved by adding a small amount of powdered langbeinite or other suitable source for Adding magnesium to the potash salt. Such a suitable source of magnesium includes the aforementioned magnesium phosphate the oxide, chloride, sulfate, carbonate, nitrate and the like. Langbeinite is produced in an amount of 15 to 35 kg / t potash used. Other magnesium salts are used in an equivalent amount of 10 to 20 kg magnesium sulfate / t potassium salt.

The granulation step is carried out in the usual manner with the usual Temperatures, for example between 71 and 94 ° C carried out. In the same way, the drying step also becomes more common Way done.

In accordance with what has been said so far, it is a The aim of the invention is to provide a composition.

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which is suitable for granulation and which is made from a potash salt and an inorganic phosphate binder. In particular, one embodiment of the invention is a composition to show which is suitable for granulation and from a potassium salt, an inorganic phosphate binder for it in an amount of about 15 to 150 kg / t of potash salt and water in an amount of 75 to 200 l / t of potash salt, wherein the potassium salt can be potassium chloride, potassium sulfate, potassium carbonate or langbeinite or mixtures thereof. Preferred Mixtures include those in which langbeinite is present as a minor component. The inorganic Phosphate is replaced by mono- or diamminium phosphate, mono- or disodium phosphate, mono- or dipotassium phosphate or mono- or dibasic magnesium sulphate or mixtures thereof educated. It is also contemplated here, according to another embodiment of the invention, granulated compositions of the aforementioned materials containing between about 85 to 98% potassium salt and 15 contain up to 1.5% binding agent. In addition, the granulated Composition Contain residual water in different amounts, although in general the composition in the is essentially anhydrous.

The invention is illustrated in the following examples. These examples are not to be interpreted in a restrictive manner.

example 1

A dust collector turned into fine-grained Langbeinite used for granulation. The analysis

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showed that they have 5% particles with a size of +35 mesh and contained 26% particles of -200 mesh size. The granulator was operated at a speed of 15 t / h, 150 kg of a mixture of mono- and diammonium phosphate / t Langbeinite were used. The ammonium phosphate was formed in situ by adding phosphoric acid formed by the wet process in suitable proportions and the mixture ammonated with a molar ratio of about 1.5 moles of anhydrous ammonia per mole of phosphoric acid.

Granulation was carried out in a TVA rotating drum ammonator according to U.S. Patents 2,729,554 and 2,741,545. Water was added as necessary to keep it good To achieve granulation properties. The granulator drum was operated at a temperature of 81 to 83 ° C. The moisture content of the granulated product after it comes out from the granulator was 14%. The product was then fed to a dryer having an inlet temperature of 526 to 66O ° C. The temperature of the outflowing gases was 93 to 107 ° C and that of the dried product 43 to 49 ° C.

Satisfactory granulation was achieved, as shown by the sieve analysis in Table 1.

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Table 1

co

OO Ca>

O OI

% Cumulative

Mesh sieve

size (Tyler) 6 8 10 14 20 35 65 100 200 -200

Admitted: 3.5 19.7 37.3 73.6 26.4

Granulation at

150 kg / t 0.5 6.9 71.4 99.3 0.7

Granulation at

50 kg / t 0.8 17.8 59.1 90.9 9.1

ο ι

CX)

ro CD

A disintegration test was carried out and it was found that 8.4% disintegrated. This shows the advantageous degree of disintegration of granulated potassium sulfate and diammonium phosphate at. The physical properties of the product were acceptable.

Example 2

The experiment of Example 1 was carried out in all essential details repeated with the exception that the mono- and diammonium phosphate content was reduced to 50 kg / t. It Satisfactory granulation was achieved, as can be seen from the sieve analysis of Example 1. In an attempt to disintegrate a disintegration of 7.4% of the granules was found. The physical properties were acceptable.

Example 3

1 t of potassium chloride was mixed with 50 kg of monoammonium phosphate and 100 l of water (10%) mixed in a pan granulator and granulated in a known manner at 82 ° C. That the granulator leaving material is dried, refrigerated and stored. The physical properties are acceptable.

Example 4

The experiment of Example 3 is repeated in all essential details with the exception that potassium carbonate is used

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used instead of potassium chloride and diaramonium phosphate instead of monoammonium phosphate, and that 20% water is added. A satisfactory physical one is obtained Quality of the granules.

Example 5

The experiment of Example 3 is repeated in all essential details with the exception that instead of potassium chloride Potassium sulfate used and instead of monoammonium phosphate 15 kg / t monosodium phosphate, as well as 7.5% water be used. The physical properties of the granules are satisfactory.

Example 6

Example 3 is repeated in all essential details, with the exception that instead of potassium chloride, potassium nitrate is used and instead of monoammonium phosphate 50 kg / t of monopotassium phosphate are used. The physical properties of the granules are acceptable.

Example 7

The experiment of Example 1 is carried out in all essential details repeated except that disodium hydrogen phosphate is used instead of ammonium phosphate. The physical Properties of the granules are acceptable.

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Example 8

The experiment of Example 7 is carried out in all essential details repeated except that dipotassium hydrogen phosphate is used instead of disodium hydrogen phosphate. The physical properties of the granules are acceptable.

Example 9

The experiment in Example 3 is repeated in all essential details with the exception that instead of ammonium phosphate Langbeinit is used. The physical properties of the granules obtained are acceptable.

Example 10

The experiment of Example 1 is carried out in all essential details repeated except that potassium chloride is replaced with langbeinite and magnesium oxide instead of ammonia is used in an amount that there is an equimolar ratio with the phosphoric acid. The physical Properties of the granules obtained are acceptable.

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Claims (4)

PATENT CLAIMS 1. Method of granulating potassium chloride, potassium nitrate, potassium sulfate, potassium carbonate, langbeinite or Mixtures thereof with the formation of granules, characterized in that the potash salt with mono- or dibasic ammonium, sodium or potassium phosphate as a binder in an amount of 15 up to 150 kg / t potassium salt mixed with water, the mixture granulates and dries. 2. A method for granulating Langbeinite, characterized in that Langbeinite in a granulator, 7.5 to 20% water is added, a mixture of mono- and diammonium phosphate, which 809823/0561 ORIGINAL INSPEGTE '. was obtained by reacting ammonia and phosphoric acid in a molar ratio of about 1.1-1.5: 1 is added, the mixture thus obtained is granulated and dried. 3. Granulated composition, characterized by a content of 85 to 98.8% potassium salt and 15 to 1.5% mono- or diammonium, sodium or Potassium phosphate as a binder. 4. Composition according to claim 3, characterized in that the potash salt is langbeinite and the binder is a mixture of mono- and diammonium phosphate, which is produced by reacting ammonia and phosphoric acid in a molar ratio of about 1.3-1.7: 1 is. 809823/0561