DE1248073B - Process for improving the grain hardness of granulated multi-nutrient fertilizers - Google Patents

Description

Process for improving the grain hardness of granulated complex fertilizers It is known to use synthetic organic compounds as fertilizers slower To use nitrogen fertilization. When applying these compounds in shape a compound fertilizer, e.g. B. in the form of a mixture with inorganic Fertilizers, there is the disadvantage that granules of these fertilizers are only small Possess grain hardness. The individual grains can be easily crushed.

It is also known to use a moist filter cake, as in the Manufacture of synthetic organic compounds is created, or one through Condensation in the melt produced organic compound with an inorganic Mixing fertilizers (U.S. Patent 2 864685; German Auslegeschriften 1025431, 1 122967). However, no increase in grain hardness was observed here.

Another disadvantage is that there is condensation in the melt difficult to control and regulate.

Bs is also known, a urea melt or a urea solution with an aqueous solution of a urea-formaldehyde condensation product mix (French patent specification 1 264418).

However, in this way only a nitrogen fertilizer is obtained, which contains neither phosphorus nor potassium compounds.

Finally, two earlier rights (German patents 1 139 133, 1 139 134) Process for the production of urea-formaldehyde condensation products containing compound fertilizers.

Here, after the addition of the inorganic fertilizer components made a post-condensation.

It has now been found that there is an improvement in the grain hardness of granulated complex fertilizers containing a condensation product of urea or its derivatives with aldehydes when granulating a mixture from inorganic fertilizer salts and the condensation product in per se known Way is obtained if the condensation product is obtained in the form of the crude aqueous suspension used as it is obtained in the manufacture of the condensation product.

Among the crude aqueous suspension, the suspension becomes like it present after completion of the synthesis of the organic compound, understood.

Although the raw suspension can be mixed with the inorganic Small amounts of other substances can be added to fertilizer salts, but the composition the suspension must not be significantly changed as a result.

Among synthetic organic compounds with slow nitrogen fertilization are, for example, condensation products of urea or its derivatives with aldehydes, e.g. B. with formaldehyde, acetaldehyde, butyraldehyde or crotonaldehyde, Understood.

It is advantageous to use the starting products for the granulation also the return goods, d. H. the waste generated in classifying the finished Granules accumulate as an undesirable grain size. The return goods can in this way can easily be converted into the desired grain size.

Furthermore, one sets the raw aqueous suspension of the synthetic organic compound appropriately 0.01 to 0.1 0.1% of a dispersant, because this ensures the uniform application of the suspension to the mixture of inorganic Fertilizing salts is facilitated.

The use of a crude aqueous suspension with a temperature from 50 to 70 ° C is also advantageous because in this way the toughness of the aqueous suspension reduced and thus an intimate mixture between inorganic and organic compounds in granulation is facilitated.

It is advantageous to use the raw aqueous suspension of the synthetic organic compound to the inorganic fertilizer salts during granulation.

The improvement in grain hardness by the method according to the invention is so clear that in most cases it can be determined by a pressure test with the finger can easily be determined. The grains are used for quantitative measurement with a Stamp crushed at the moment of destruction applied force can be read. The hardness values determined in this way are fertilizers that are manufactured according to the method according to the invention, much higher than fertilizers made by adding synthetic organic Connection in solid form have been established.

The fertilizers according to the invention can with the help of the known Granulation devices, e.g. B. in shaft mixers, twin-shaft mixers, in granulating drums or granulating plates.

When drying the granules, it is expedient to place them in a drying drum the temperature so that it is just below the softening point of the fertilizer synthetic organic compound.

This point is because of the moisture present in the fertilizer usually deeper than with the dry connection. The inorganic substances melt usually not yet. Of course, the temperature must not be increased that high that too strong softening with an increase in the grain size of the granules or decomposition occurs. With correct observance of the temperature of the fertilizer During the drying process, however, an increase in the grain hardness of the finished product is achieved. Just below the softening point means about 5 to 10 ° C below the softening point in the wet fertilizer mixture.

The following examples explain the process according to the invention. The parts mentioned in the examples are parts by weight.

Example 1 Production of a mixed fertilizer with contents 16: 8: 16 (NPK) with 500 in poorly soluble nitrogen content a) 68 parts of a ground Mixed fertilizers (12:12:20) are made with 4.5 parts of potassium sulfate and 27.5 parts solid technical crotonylidenediurea (30ovo N, 70 / o K2SO4) mixed and then Granulated on a granulating plate with the addition of water. The resulting granules is dried, cooled and sieved. b) 68 parts ground mixed fertilizer (12:12:20) and 4.5 parts of potassium sulfate are premixed with 140 parts of ground return material on a granulating plate with 47 parts of a crude aqueous suspension as is is formed in the synthesis of crotonylidenediurea and the approximately 54.7% crotonylidenediurea, contains about 3.80 / 0 potassium sulphate and 41.5% water and that contains about 0.010 / 0 one Dispersants are added, granulated. The granulate is then further treated as described above.

Example 2 Production of a mixed fertilizer with contents 16: 8: 16: 1 (NPKMgO) with 500 in poorly soluble nitrogen a) 67 parts of a ground mixed fertilizer (12: 12: 20) are mixed with 3.8 parts of potassium sulfate, 2 Parts of magnesium sulfate and 27.2 parts of solid technical crotonylidenediurea (30 0 / jo N, 7 ° f K2SO4) mixed and then placed on a granulating plate Granulated addition of water. The resulting granules are placed in a rotating drum dried in countercurrent with hot air at about 1000 C, cooled and sieved. b) 67 Parts of ground mixed fertilizer (12: 12: 20), 3.8 parts of potassium sulfate, 2 parts Magnesium sulfate are premixed with 140 parts of ground reflux material a granulating plate with 46.5 parts of a crude aqueous suspension such as this in the synthesis of crotonylidenediurea and about 54.7 0/0 crotonylidenediurea, contains about 3.80 / 0 potassium sulfate and 41.50 / 0 water and about 0.01 0/0 one Dispersants are added, granulated. The granulate is then further treated as described above.

Example 3 68 parts of a ground mixed fertilizer (12: 12:20) become mixed with 4.5 parts of potassium sulfate and about 200 parts of ground return material and then spraying on 53 parts of a crude suspension as they are in the synthesis of crotonylidenediurea and the approximately 48.5 0 / o crotonylidenediurea, Contains 3.50 / 0 potassium sulfate and 48 0 / e water, granulated in a twin tusk snail. This suspension can be used without the addition of dispersants. Your application requires, however, an increased addition of return material compared to Example 1 To obtain granules of the desired grain size. The final product has the composition 16: 8: 16 with 50% sparingly soluble nitrogen content.

Example 4 Production of a mixed fertilizer with contents 16: 10:17 (NPK) with about 400/0 sparingly soluble nitrogen content a) 84 parts of a ground Mixed fertilizers (12:12:20) are mixed with 16 parts of solid technical methylene urea (390/0 N, 10 / o K2So,) mixed and then on a small granulating plate granulated with the addition of water. The resulting granules are then dried, chilled and sifted. b) 84 parts of a ground mixed fertilizer (12: 12: 20) are placed on a small granulating plate with 34 parts of a crude aqueous suspension, as it arises in the synthesis of methylene urea and the approximately 47% methylene urea, contains about 0.5% potassium sulfate and 52.50 / 0 water, granulated. The granules will then further treated as described above.

The experiments of Example 1 were carried out on a small laboratory test granulating plate (40 cm diameter), those of Example 2 also on a granulating plate performed with a diameter of 160 cm.

When the grain hardness of the sieved fraction of 1.5 to 3.5 mm grain diameter is tested, the grains produced by the process according to the invention are clearly superior. The grain hardness is determined by measuring the crushing pressure; the values listed are average values from 50 individual values. Her grain hardness Fertilizers granulating | positional device procedure kg 16: 8:16 small plate fa) 0.5 b) 2.3 16: 8: 16: 1 small plate # a) 2.1 b) 3.5 16: 8: 16: 1 large plate (a) 1,3 -tb) 2.2 16: 10:17 small plate Y a) 1,1 #b) 2.2 Since the grain hardness depends, for example, on the load and the inclination of the plate, on the management of the drying process and other factors, the values of the grain hardness can only be compared with one another in a series of tests carried out under exactly the same conditions.

Claims (4)

Claims: 1. Method for improving the grain hardness of granulated complex fertilizers containing a condensation product from Urea or its derivatives with aldehydes by granulating a mixture from inorganic fertilizer salts and the condensation product in per se known Way, d a -characterized in that the condensation product is in the form of the crude aqueous suspension used as it is in the preparation of the condensation product accrues. 2. The method according to claim 1, characterized in that the Adding raw materials for the granulation of the return material. 3. The method according to claim 1, characterized in that the aqueous Suspension of the condensation product from 0.01 to 0.1% of a dispersant was added will. 4. The method according to claim 1, characterized in that the aqueous Suspension is kept at a temperature of 50 to 70 ° C. Publications considered: German Auslegeschriften No. 1025431, 1122967; French Patent No. 1264418; U.S. Patent No. 2 864685. Older patents considered: German patents No. 1,139,133, 1 139 134.