DE664070C - Process for the production of a coarse-grained storage-stable ammonium bicarbonate - Google Patents

Description

Process for obtaining a coarse-grained storage stable ammonium bicarbonate Attempts have already been made to create a z. B. sufficient for use as a fertilizer to produce storage-stable ammonium bicarbonate. For this purpose one has the fixed Salt slightly water-absorbing salts such as Na2S04, Mg S04 and others. One has also subsequent coatings of less hygroscopic substances such as chlorammonium generated by the crystals. There is the water that adheres to the salt from its manufacture easily causing its subsequent decomposition, the drying of the solid Bicarbonate made in a carbonic acid or in a carbonic acid ammonia atmosphere. Other proposals have been to remove the mother liquor before the solid salt is separated water-soluble stabilizers, such as sugar, or alkylnaphthalene sulfonic acids, as protective substances or organic liquids such as tar oils, gasoline, ligroin, carbon tetrachloride etc. to add. Furthermore, the separated ammonium bicarbonate is also available with or .Without cementing substances pressed into moldings in order to create the salt surface in this way to reduce the risk of evaporation during storage. Finally has one also tries, if possible, to use foreign salts and enclosed mother liquor to produce free salt in that one during the whole duration of the crystallization maintains an excess of carbonic acid in the solution. Really satisfying results arguably have not been achieved with any of these processes.

A much simpler and safer solution to this problem is provided now the new knowledge on which this invention is based, from which shows that none of the additional measures listed above are required at all, by sufficient storage-stable ammonium bicarbonate in the form of more uniform, coarse-grained To win crystals. The representation of the same succeeds in an extremely simple way. As tests made in this direction have shown, one receives namely when introducing of carbonic acid in free ammonia-containing solutions then a coarsely crystalline Salt, which has sufficient shelf life if you add the carbonic acid and with it the crowd. newly formed ammonium bicarbonate from the time where the solution is saturated with ammonia carbonic acid compounds and the Deposition of the ammonium bicarbonate should begin, dosed and ensures that the Amount of the deposited solid salt with that newly formed by the introduction of carbonic acid Amount of ammonium bicarbonate keeps pace. For this purpose only one is allowed to Lye volume and the amount of carbonic acid in a certain proportion to the unit of time are fed. Here it is irrelevant whether this carbonic acid supply through Passing through of more or less completely absorbed carbonic acid takes place or whether a passing of the carbonic acid over the solution, which in a closed Vessel, in a shaking cradle o. The like. Is, takes place. Is decisive alone the amount of carbon dioxide absorbed in the unit of time or the amount caused by it Increase in the amount of ammonia carbonic acid compounds in the solution.

Will the emergence of the additional, exceeding the saturation limit Amounts of ammonia carbonic acid compounds by dosing the carbonic acid as well If the appropriate crystallization time measure is chosen correctly, then the degree of saturation becomes the amount of bicarbonate exceeding the lye is fully used for crystal formation or for the Growth of already existing crystals or crystal nuclei exploited.

Experiments have shown that to achieve such a salt of the required grain size per liter of saturated ammonia carbonic acid compounds Solution and no more than 8 to 24 g of salt per hour at room temperature for separation are allowed to come. Accordingly, no more than 2.4 liters of lye per hour up to 7.31 carbon dioxide are absorbed. If this amount is exceeded, then it is exceeded the amount of ammonium bicarbonate formed is the limit of what is produced by the Crystals on new material can be grown so considerably that new crystallization nuclei must appear to such an extent that a whole in the sieve analysis when salt is too fine-grained.

The limit given above for the allowable amount of newly emerging Salt must therefore be given in stretched form, because at the beginning of the salt excretion only a few crystals are present, while at the end the largest number of crystals is present. In addition, there is therefore greater leeway for practical needs necessary because a certain temperature is not always present during operation, but depending Depending on the season, the quality of the cooling equipment, the temperature of the cooling water and the duration a certain temperature interval can be expected during the operation. Basically would, however, be for no and the same temperature and a definite sieve analysis result only a very specific, sharply defined dose of carbonic acid is permitted.

The experiments to determine what amounts of collenic acid per volume a solution that is saturated with ammonia carbonic acid compounds are permitted, were carried out as follows: In three juxtaposed vessels of similar Shape, but of different sizes and 39o cc, 16o cc and 6o cc content Solution which was saturated with ammonium bicarbonate, but no crystals precipitated yet and 3.2% free ammonia, i.e. H. contained NH3 not bound as N H4 H C 03, carbonic acid was introduced. This was done in such a way that in the middle of a a wide glass tube was inserted into the liquid in each of the round vessels, which reached from the bottom to the surface of the liquid. Through this glass tube was then an ascending stream of carbonic acid with the help of a capillary tube sent. This caused an ascending flow of liquid in the manner of mammoth pumps was generated in the centrally inserted glass tube, which over the edge of this Tube overflowed and so in the entire vessel a constant flow of liquid generated.

The carbon dioxide introduced was not completely absorbed. Since the The size of the centrally inserted glass tubes was the same in all three vessels and just as the carbonic acid flow was kept s: ark, so only the could amount of carbon dioxide absorbed and the vivacity with which the liquid is in motion was to be different.

The following were deposited in the first vessel with a volume of 39o ccm: 10.25 g of N H4. HC 03 per liter and hour and 3, z 1 CO. absorbed, in the second 25.49 N H4 HC 03 per liter and hour and thereby 7.7 1 CO ,, absorbed, in the third 26.3 g NH, HC 0y3 per liter and hour and thereby 7.971 CO, absorbed.

The S; Izpröben resulted in the following sieve analyzes in the first vessel: under o.5 mm ro.4o / o.5 to rmm 23.75%, 1 to 2mm 54.6%, over -mm 11.25%; in the second Vessel: under 0.5 mm 33.60, o, 0.5 to i mm 25.4%, 1 to 2 mm 41%; in the third vessel below o.5mm 37.4%, o.5 to i mm 34.90; ö, 1 to 2 MM 27.70 / 0.

One can clearly see that in the smallest vessel, in which the largest Amount of carbonic acid was offered to the smallest amount of liquid, the finest-grained Salt was created while the better salt was kept in the larger vessel. In the same The dependence of the grain of salt on the one presented became wise Amount of carbonic acid determined in a closed shaker.

In these experiments the volume of the liquid was constant and its composition corresponded to that in the above experiments. The liveliness of the carbonic acid absorption was regulated by shaking the duck to a greater or lesser extent mechanically. It was found that, as was to be expected, the greatest amount of carbonic acid was sucked in with rapid shaking and that the best salt was obtained with little or no movement of the duck with little carbonic acid absorption. In detail, the following results were obtained: 1. 83 g NH, HC03 per liter of lye and hour with absorption of 25.2 1 C02 per hour. 2. 34 g NH, HC03 _ _ _ - _ _ _ _ I0.31 C02 - _ 3. 9.6 g NH, HC03 - _ _ _ _ _ _ - _ 591 C02 _ The salt samples resulted in the following sieve analyzes: i. Less than 0.5 mm 3o.8 per cent. 0.5 to 1 mm 69.2 per cent. 1 to ? mm o ° 2 to 3 mm o ° / o. 2. - 0.5 mm 14.2 ° / o, 0.5 - 1 mm 40.3 ° / o @ 1 - 2 mm 45.5 ° / o, 2 - 3 mm. 0 ° / o. 3. - 0.5 mm 6.25 ° / o, 0.5 - i mm i9.8 ° / o, i - 2 mm 6e45 ° / o, 2 '3 mm 4.5 °;' o. Only the N H4 HC 03 obtained after 3 met the requirements for the grain size. Here, 5.91 carbonic acid was absorbed per liter of absorption liquid, which corresponds approximately to the mean of the carbonic acid uptake required above per liter and unit of time.

As for the influence of the grain size of the salt on the shelf life, the following experiment provides information on this.

In each case 5 g of salt were placed in a circle on a laboratory ear glass 4 to 5 cm in diameter and with a layer thickness of 3 to 5 mm; spread out and in a weakly heated living room left to stand in the air for about a month without the humidity, which changes depending on the weather, has been taken into account. Air-dry salt was used, which was sifted out according to different grain sizes had been.

The following test results show the influence of the grain size on the storage stability of the salt. In order to determine this, salt with a grain size of 1 to 2 mm, a grain size of 0.5 to 1 mm and finally fine salt of less than 0.5 mm were used. In addition, an unscreened PrGbe of ammonium bicarbonate (colliery product) produced technically without any precautionary measures was used for comparison. The salt was either weighed daily or, where this result is not given in the table below, the mean of the daily individual losses is used. Table i Grain greetings of weight loss on air dry sifted t. 2. I .1. I o. I 12 15 2 a. 25th Salt observation days in ° / " I. I. 1 mm . . . . . . . . . . . . . . . 0.41 0.45 0.51: 0.52 0.54 0.44 0.48 0.55 0.5 to 1 mm. . . . . . . . 0.54 0.56 o, 67 I o, 69 o, 76 o, 605 0.71 o, 69 under 0.5 mm. . . . . . . . 1.11 1.29 1.53 1.5 1.2 1.75 1.56 1.8 Colliery salt j (unloved) ..... 1.39 1.37 1.66 1.71. 1.97 2.08 1.97 2.49 These loss figures show how much more favorable the coarse-grained, well-crystallized salt is compared to the fine-grained technical product.

A comparative experiment will be described below, which also the superiority of the salt prepared according to the invention over that according to a known ver. drive with the addition of carbon tetrachloride shows.

a) 2oo ccm i 5% ammonia water, the 14.0 ccm carbon tetrachloride added were, while stirring with carbonic acid in excess treated, whereby 678, above-mentioned ammonium bicarbonate come to the excretion. The bicarbonate is sucked off well and dried by storing on filter paper.

b) In 2000 ccm i 5% ammonia water, which was already saturated with carbonic acid until shortly before the start of crystallization in order to save time, 12 to 141 carbonic acid are introduced every hour. The temperature of the solution rises to 25 °. 440 bicarbonate is deposited, which is dried like the ammonium bicarbonate obtained in Example i. Storage test Each draw of the products obtained according to Examples 1 and 2 are stored on watch glasses at 2 5 and 35 ′ under otherwise identical conditions. The weight losses obtained after 100 hours are shown in the table below. Table II ,., Salt pattern. 25 ° 35 ° ? ' I,% 2% 2g 9.5oz6g fell z. . . . . . . . . . 8.64% 47 # 4% Example 2.. . . . . . . . . 088ö6 g 5.3396 4.43; 0 26 # 7 ro

Claims (1)

PATENT CLAIM: Process for obtaining a coarse-grained shelf stable Ammonium bicarbonate by introducing carbon dioxide into an ammonia-containing one Ammonia carbonic acid compounds saturated solution, characterized in that one per liter of solution no more than 8 to 24g ammonium bicarbonate per hour for separation and no more than 2.4 to 7.31 carbonic acid per hour per liter of salt solution can be absorbed.