DE2231816A1 - Low-dust, non-caking calcium ammonium nitrate granules prodn - by mechanical cleaning steam treatment and coating with anticaking agent - Google Patents

Abstract

A non-caking granulated Ca ammonium nitrate (I) with a low dust content is produced by (a) mechanically cleaning granulated (I) to remove dust adhering to it; (b) treating with steam; and (c) coating with a molten organic anticaking agent at a temp. below the transition temp. (32 degrees C) of (I). The starting material is pref. granulated (I) which has been treated with a powdered inorganic material (esp. lime), pref. at room temp., and then stored for a certain period. The steam treatment binds any remaining dust and improves the uniformity of the anticaking agent coating. (I) is a fertiliser.

Description

Process for the production of a low-dust, non-baking granulated Calcium ammonium nitrate The invention relates to a method for producing a low-dust, non-baking granulated lime ammonium nitrate by treating the granulated Starting material with steam and application of an organic compensation agent.

It is known to apply liquid organic fertilizers To remunerate anti-caking reagents. In principle, between the remuneration of hot and cooled salt differentiated, di. hereinafter referred to as "hot" and "cold tempering" are designated.

In the case of hot tempering, reagents with a melting point of approx. 60 - 120 ° C, given up on the uncooled courtship (80 - 1100C). The subsequent Cooling the salt means solidifying and solidifying the organic coating, so that, in addition to the anti-caking effect and the water repellency, surface protection is provided Abrasion is achieved. For this reason, the hot annealing is also very often called Called fertilizer sealing.

The application of organic substances takes place in the ball of the cold tempering Salt cooled to 15-30 ° C with melting points <50 ° C. The one at room temperature liquid to pasty organic coating primarily means protection against caking and water absorption (hygroscopicity) of the salt. One This does not result in increased resistance of the granulate to abrasion.

Lime ammonium nitrate is known to have in the aforementioned temperature ranges two transformation points (see Gmelin, vol. 23, page 95): at around 81 ° C, di. conversion with an increase in volume at around 320C, it takes place with a decrease in volume.

Of course, these transformations are not spontaneous However, the faster the temperature reduction occurs, the greater the delays the lower the transition temperature (see Gmelin, Vol. 23, Beite 97). According to experience the conversion process can take up to about 6 days. So it must also be used for storage can still be expected with umw @@@ lungen.

This is the reason that primarily well adhered to fresh goods Coatings later loosen their bond to the base material and are thrown off as dust will. This will happen in particular if the remuneration p @ zeß in the temperature range around 32 ° C and below takes place, i.e. with the so-called cold tempering. An underpowder with inorganic agents, e.g. powdered lime, this phenomenon must be intensified.

Since mineral fertilizers are generally initially produced after manufacture saved before they go to Shipping come, you have it so far treated with inorganic powder agents prior to storage. For this purpose Limestone powder has been used in particular. After saving and before The dispatch was then another part of the same powder agent or else a different one, e.g. kieselguhr, applied (German patent specification 941 195). The fertilizers obtainable in this way already show a proportionate good storage behavior, but the abrasion on fine grain and the dust content of the Handling of fertilizers impaired, relatively high, as in the test series I can be seen in the attached table 1. The cooled granulated calcium ammonium nitrate was used with 2 to 2.5% powdered lime before storage and with 0.7% kieselguhr treated after storage.

It is also known to use organic substances of all kinds, E.g. amines, to be applied to fertilizers so that they can flow freely even after prolonged storage to obtain. According to n & sS 1 075 642, the distribution of these substances is determined by the Increased presence of small amounts of water.

The use of organic remuneration or sealing agents, which were applied to the cooled granulate before storage, led a calcium ammonium nitrate with a relatively low amount of dust, but it was In this case, the storage behavior is unsatisfactory, as test series II (Table 1) shows. Here 0.18% organic remuneration agent was applied.

Also the treatment with a lime powder application of 0.5 SC and afterwards Applying 0.18% of an organic compensation agent could improve the storage properties only Improve insignificantly, as test series III shows (Table 1).

The task was thus to find a treatment method with the one that is flowable even after a long period of storage under high loads, not caking calcium ammonium nitrate granules can be obtained. It should continue show only a small amount of dust, as the dust is returned from the coated product The graying ability of calcium ammonium nitrate is decisive in the manufacturing process deteriorated, so that one of the unsealed or only with inorganic Powder-treated fertilizers refrain from the usual recycling of dust. the Abraded fines therefore represent a loss.

The invention resides in a method of making a non baking granulated lime ammonium nitrate, which is characterized in that granulated Ialkammonsalpeter first mechanically freed from adhering dust with steam treated and then at a temperature below the transition temperature of the calcium ammonium nitrate of 32 ° C with the melted organic remuneration or sealant is coated.

Jan, if, is given a particularly well storable lime ammonium nitrate this after granulation with per se known powdery inorganic Material powdered and before the above-mentioned treatment for a certain period of time, expediently has been stored for at least 6 days. Suitable inorganic substances oind in particular limestone powder, also kieselguhr and other silicic acid Substances, talc, clay, etc.

The covering with the inorganic material is vsw.

also made at room temperature.

The application of an inorganic powder composition along with steam on granular solids is known from the German Auslegeschrift 1 230 401, but there is such a process for hygroscopic substances, for example fertilizers as unsuitable.

The advantages of the method according to the invention are provided by the in Test series IV and V shown in Table 2 are illustrated.

For test series IV, calcium ammonium nitrate was used before storage with 0.12% of an organic anti-caking agent in combination with a direct 0.15 - 0.2% steam pretreatment of the salt surface cold tempered.

For test series V, chilled food was coated with 2 - 2.5 * Pudorw lime Lime ammonium nitrate granules after at least six days of storage during the withdrawal via fluidized bed and sifter mechanically cleaned in one Drum subjected to a 0.1 fiigx steam treatment and then with approx. 0.08-0.1% of an organic anti-caking agent cold-conditioned.

The result is a well storable lime ammonium nitrate product, its Screening and abrasion values are comparable with those according to test series IV, however, in contrast, have somewhat higher dust values.

Table 1 Ver C-Ge shear load water grain dust screening abrasion sifter sack pile search- stop at 45 ° C content hardness test assessment series% kg% kg g / tg / tg / tg / t Up to bag position 25 even after several mo- I - 2-7 0.50 2-3 250-450 50-3000 260-500 3000-4000 natural service life satisfactory Storage behavior After four weeks Storage from sack II 0.15 9-13 0.45 2-3 30-150 50- <150 <100 100-400 layer 18-20 un- peaceful camp properties After four weeks Storage from sack III 0.15 2-6 0.45 2-3 100-200 50-200 <100 400-700 position 18-20 un- peaceful camp properties Table 2 Ver C-Ge shear load water- grain- dust Absie- abrasion classifier- sack pile- search stop at 45 ° C content hardness exercise test assessment series% kg% kg g / tg / tg / tg / t After four weeks of standing time to bag position 24 sufficient storability IV 0.1 10-13 0.52 2-3 <100 <100 <60 100-200 speed, after several months Storage only up to finally bag position 18 satisfactory. Even under extreme conditions load conditions V 0.066- 0-0.1 0.55 2-3 60-200 <100 <60 200-500 (up to position 31) after 5 - 0.083 10-week storage time good storage behavior The steam treatment supports the cleaning by binding in residual dust and also promotes the spreading of the organic coating on the grain, so that a completely uniform coating of the individual grains is guaranteed.

In-depth investigations have also shown that after deposition Tempered calcium ammonium nitrate when exposed to moist air under pressure with regard to its tendency towards caking. Advantages over without deposit with organic Shows hardening agent treated calcanite nitrate. To this end, two were made Test series a and b carried out, which are shown in Table 3.

For test series a, cooled calcium ammonium nitrate granules were used Treated with steam and provided with 0.1% organic hardening agent. For test series b Lime ammonium nitrate powdered with lime was stored, then treated with steam and also coated with 0.1% organic compensation agent. Different samples the fertilizers treated according to a and b were spun for a certain time. one Air flow of 4000 and 70% relative humidity exposed and the shear load determined.

Table 3 away Duration of exposure Moisture shear load Moisture shear load salary salary (%) (kg) (%) (kg) Initial state 0.2 4.5 0.4 0 5 minutes 0.5 8.0 0.7 2.5 10 0.8 20.0 0.9 6.0 15 1.0 26.5 1.1 10.0 20 1.1 31.5 1.3 14.0 25 1.3 - 1.4 17.0 30 1.4-1.5 18.5 The method according to the invention is suitable for applying any organic coatings known for cold tempering to calcium ammonium nitrate, such as amines and amino acids (DOS 1 442 857), amine-paraffin wax mixtures (USSR 197 316), amine-oil mixtures, oil-like substances (Brit.P. 583 388), sulfones and sulfonates (GDR-P. 62 314 reported in the progress report 24095/1969), mixtures of waxy polyethylene and amines (DOS 1 947 874, 2 018 623).

The percentages for steam treatment relate to on the weight of water absorbed by the calcium ammonium nitrate. She is going through regulates the pressure of the steam fed in.

The application of the 2 to 2.5% powder lime in test series I, III, V and b, were carried out in the usual way in a drum.

As a coating or sealing agent in the test series II bia V as well as a and b became a stearylamine paraffin wax preparation (weight ratio 1 s 2) with a melting range of 37 - 51 ° C. It was on the order 0.09 - 0.12% with a temperature of 60 to 80 ° C on the one in a rotating drum located cold granulated calcium ammonium nitrate.

The mechanical removal of product dust and powder lime dust 90% of the calcium ammonium nitrate was carried out in a fluidized bed, then in a sifter, in which, as usual, undersized particles are separated.

The determination of the characteristic data for the shelf life of calcium ammonium nitrate: shear load, dust accumulation, sieve and abrasion test, The classifier test, grain hardness, water content and bag stacking test are described below.

1. Checking the shear load Two superimposed V2A rings (clear Width 39 mm, height 25 mm each) are up to 2 mm below their edge with the to be tested Salt filled and sealed with a polyethylene stamp on the top Page has been widened so that it serves as a support base for the next pair of rings can. A total of five pairs of these rings are placed vertically on top of each other in a plastic tube arranged, with the lower base and upper stamp by means of rubber hoses the Hermetically seal the system to the outside. The specimen is after two days Storage under room conditions vertically in a thermostat-controlled climatic cabinet at 45 ° C under 20 kg load - corresponding to 1.7 k vem2 surface load - used. After a standing time of 6 days, the sample carrier is removed from the climatic cabinet and stored horizontally for approx. 24 h below room temperature. Then the five Individual samples are carefully removed from the pipe shell and placed in a specially designed one set up apparatus sheared apart. The mean shear force applied for this purpose of the five individual samples is a measure of the tendency towards caking and shelf life of one Thin salt.

2. Determination of the water content of salt samples in the order of magnitude 20 g are poured into small glass vessels, weighed and placed in a drying cabinet at 11000 dried for 1 h. From the weight difference before and after drying, determine the water content relatively easily. To reduce external influences are the samples are hermetically sealed outside of the drying tank during manipulation.

3. Determination of the grain hardness To determine the breaking load or grain hardness of a fertilizer granulate, the 2 - 3 mm sieve fraction of a sample turns into 30 grains removed regardless of their shape and carefully between two with a pair of tweezers Pins of 3 mm pl are placed, with the upper pin by means of a spindle vertically against the fixed lower is stirred. Via a spring pressure gauge with a drag pointer read directly the force used to break the mandrel. From each 10 Values are averaged.

Differentiate from the three mean values found in this way, greatest and smallest Average value not more than 20%, gives the calculated thirty individual measurements Average value of the breaking load or grain hardness in kg.

If there are larger deviations from the mean values, then in each case another 10 grains crushed until three series are present, the condition mentioned above fulfill.

4. Dust test On an analytical balance, 100 g of fertilizer granules are in Weighed in a 200 ml wide-necked Erlenmeyer flask and poured it over a funnel poured into an approx. 400 fl long and 80 ° inclined downpipe. The granules trickle into a second 200 ml wide-necked Erlenmeyer flask serving as a collecting vessel, whereby the air entrained by the sample material escapes in the form of a small cloud of dust.

After going through the trickle section six times, the is replaced by a Analytical balance determined weight loss defined as dust in g / t of goods.

5. Sieving and abrasion test a) 100 g of fertilizer granules are placed on a balance weighed and one minute by hand on a sieve with a mesh size of 0.5 x 0.5 mm sifted. The sieve passage transferred into a small bowl with a clean brush is weighed on an analytical balance and indicated as a sieve in g / t of goods.

b) The granulate, freed from the fines, is placed in a 200 ml narrow-necked Erlenmeyer flask decanted and fixed there by means of a short agitator arm whose height setting is fixed is kept in motion at 250 rpm for 10 minutes. The again according to the above procedure The screening carried out denotes the abrasion in g / t of goods.

6. Classifier test On a scale with an accuracy of +0.02 g, 400 g fertilizer granules weighed into a 500 ml Erlenmeyer flask and poured over a feed funnel an approx. 1 450 mm long separator section metered with dry nitrogen is applied at 1.5 m / sec. The goxichtote product ends up in a 500 ml Round-bottomed flask that is positively connected to the base of the separator tube. To The dust loss of the sample can be seen by passing through the classifier section eight times Calculate from the weight difference before and after viewing in g / t of goods. The during the Sighting of the granulate due to the low N2 water content is taken into account in the form of a correction experience value.

7. Sack stack assessment 50 kg sacks with the fertilizer granules to be tested are usually stacked in 25 layers. The after one or several months Storage carried out inspection of the stacks, with those filled with dom test salt Sacks being stacked, thrown across corners and cut open is made possible by hand the caking is a sufficient assessment of the storage quality of a product.

Claims (4)

Claims 1.) Process for the production of a non-baking granulated lime ammonium nitrate, characterized in that granulated calcium ammonium nitrate initially mechanically from freed adhering dust, treated with steam and then with a Temperature below the transformation temperature of calcium ammonium nitrate of 32 ° C with the melted organic remuneration or. Sealant is coated. 2.) Method according to claim 1, characterized in that calcium ammonium nitrate is used, which after granulation with an inorganic, powdery Material has been powdered and stored for a period of time. 3.) The method according to claim 2, characterized in that the powdering is made with the inorganic material at room temperature. 4.) Method according to claim 2 and 3, characterized in that as inorganic powdery material lime is used. -