DD136956B1 - METHOD FOR PRODUCING NON-DUSTING ABRASIVE CALIDUIN AGENT GRANULES - Google Patents

Description

205712

Title of the invention

Process for the preparation of non-dusting abrasion resistant potash granules

Field of application of the invention

The invention relates to a process for improving the physical quality of mineral fertilizers, in particular potash fertilizers, which are present in granulated form and, in particular, are transported and stored in bulk.

Characteristic of the known technical solutions

In the potash industry, part of the fine-grained potash fertilizers produced are processed by dry-pressing granulation, occasionally also by agglomeration of moist material in granulating drum η, into coarse goods. Products are made having a grain span which is preferably between about 1.0 and 4.0 Dim. The granules produced consist of angular grains which are characterized by partially satisfactory mechanical strength and density.

The disadvantage is that abrasion occurs during transport and handling of the granules, which leads to an unacceptable increase in Peinanteils. This inadequate abrasion resistance dgr granules leads to inadmissible dust formation and

Salt losses and thus to a work-physiological burden on employees and a significant environmental impact. These negative effects are explained by various factors, such as lower and

205712

The strength of Gramate single grains, the shape of the granules such as existing edges, tips, the adhesion of the dust particles adhering to the granules, and the transport and handling processes used in each case are determined.

A process is described according to which a ribbon-shaped rag is produced from fine-grained potash salts with the aid of roll presses after the contacting process, which is then comminuted and brought to the desired particle size via sieve classification. A brittle granule is obtained which is subsequently transported - And handling processes is exposed to a grain disintegration. The product is sieved, Ш? to remove the styub content. The actual amount of dust that adheres to the granules, but can not be removed by a simple sieving. The dust adheres to the irregular surface of the granules. In the steam treatment at 79 to 11o ° C only a small part of the adhesive dust is dissolved. The dissolved amount of the adhesive dust also falls after drying again in fine crystals, so that the dust behavior of the product thus treated is not improved.

It is known to separate undersize fractions (finest grain fractions) by sieving. However, the forces acting in the Siebklassierung forces are not sufficient to remove the finest adhesive dust from the granule surface, so that the Feinstkornanteil after sieving can be up to o, 4 % . A product treated in this way is still dusty.

It is known that the addition of polymerizable organic substances, the dust particles can be relatively firmly bonded to the surface of the granules. The disadvantage here is that in order to achieve the dust-binding effect relatively large amounts of these substances must be applied to the granules. On the other hand, other utility properties of the granules are thereby adversely affected.

It is also known, through the production of artificial abrasion, which takes place later during transport and transhipment mechanical

2 0 5 7 12

Stress on the granules already made by the manufacturer and separate the resulting Ifeinstkornanteil by Kontrollsiebung. In the ft? Axis, however, it is found that, under the following conditions of transport and handling, dust nevertheless arises due to attrition.

Object of the invention

The object of the invention is to eliminate the disadvantages, such as the high degree of dust formation of the granules during handling and transport processes, caused by the inadequate abrasion resistance of the granules and to achieve an improvement in the use value with respect to abrasion and dust behavior.

Explanation of the essence of the invention

The invention has for its object to improve the abrasion behavior of the granules so that the Peinanteil is not significantly increased during transport and handling and thus do not dust this.

It has been found that non-dusting and abrasion-resistant potash fertilizers can be produced when the potash fertilizers are subjected to post-treatment after the granulation process. The combined use of the process steps dedusting of the granules, subsequent treatment of the granule surface with water or aqueous additives, drying using the heat capacity of the resulting in the production process with 4o - 80 ⁰ C accumulating granules and subsequent cooling surprisingly leads to such non-dusting and abrasion-resistant Kalidimemittittelgranulaten, as so far have not been achieved by any known method. The use of only one of these steps alone or their incomplete application brings no satisfactory improvement of the abrasion and Staubverhaltons of the granules. An essential feature of the invention is therefore the combined use of several Verfahrenssteilschritto.

2 05712

According to the invention, the first process substep is that the dust particles adhering to the potash granules are removed by strong air streams in the fluidized bed. Subsequently, in the second Verl'ahrensteilschritt the dusted in the fluidized bed granules are wetted with water or aqueous additives to eliminate the remaining unstable peaks and edges that would lead to attrition again. Due to the dedusting previously carried out in the fluidized bed, the additional amounts are o, 5 - 2 % water. In the third process step, by utilizing the heat capacity of the granulate or the use of preheated air streams, the evaporation of the majority of the caustic solutions of the granules is achieved, and the granule surface is solidified by recrystallization processes. The granules are then cooled to approximately ambient temperature. The process is controlled so that Eestwasser still remains on the granules surface of preferably o, 1 - o, 2 % ; This residual moisture binds the fines which are still produced up to the end user through the transport and handling processes.

By an additional addition of organic substances, preferably of mineral oil, evaporation of the residual water can be delayed and an additional dust binding can be ensured at a later secondary dust accumulation.

The invention will be explained in more detail in the following embodiment.

AusführuDgsbeispiel

The potash fertilizer granules are dedusted before being loaded by strong air streams in the fluidized bed. DiQ Whirling times for dust-free blowing of the granules depend on the adhering amount of dust, the amount of air, which is at the existing grain size of potash fertilizer granules preferably 2-3 ш / s and the throughput and are in the range of seconds 3 ^ 5 see.

Subsequently, in a mixing section, the wetting with o, 5 - 2, o%, preferably 1 % better and its uniform

2 05712

Distribution on the entire granule surface. The granules thus treated are then dried with strong, in case of need preheated air streams and then cooled with air, drying and cooling in the fluidized bed so that a separation and discharge of the undersize occurs according to the desired separation section. This process should be adjusted so that residual moisture of preferably o, 1 - o, 2 % remain on the granules.

With the addition of organic substances, preferably mineral oils in amounts of o, 2 - 1, o g / kg, which can be done by Aufdüsen in the outlet part of the fluidized bed, the conditioning of the granules is complete.

The following quality improvement was achieved by the described granulate aftertreatment:

Dust value ¹ ^ abrasion test ² )

in к / к ζ in %

Granules untreated corresponding to micro grain content 1.1 - 3 »5 18

Granules in the fluidized bed, dedusted o, 5 18

Granules with o, 5% water

treated and dried o, 4 12

Granules with 1, o% water

treated and dried o, 2 9

Granule samples which are treated with water after fluidized-bed dusting and which still contain residual moisture after drying, showed the following amounts of newly formed abrasion in the Abxieb treatment in a roller drum after 10 minutes of drum running time.

^ Dust value determined according to TGL 29 621

• 'Abriebtest to Werkstaridardentwurf of the VEB Kombinat KALI Sondershausen from Nov. 72

205712

Granules untreated, dedusted

Granules treated with 1 % water, moisture content o, 1 %

Granules treated with 1% water, residual moisture о, 2%

Abrasion amount St value in % ing / kg__

o, 3S

o, 2

o, 12

1.8

o, 8

o, 3

Claims (5)

Process for the preparation of non-dusting abrasion-resistant potash fertilizer granules, characterized in that after the actual granulation process the potash fertilizer granulate is subjected to several combined processing steps consisting in dedusting the potash fertilizer granules first in the fluidized bed, then at a temperature of the granules of 40 ° - 80 ⁰ C wetted with 0.5 - 2% water and then dried with strong, optionally preheated air streams and then cooled to room temperature. 2. A process for producing non-dusting abrasion-resistant potash fertilizer granules according to item 1, characterized in that the dedusting of the granules takes place at air velocities of preferably 1-4 m / s in the fluidized bed. 2 0 5 7 12 invention claim 3 * A process for the preparation of non-dusting abrasion-resistant potash fertilizer granules according to item 1, characterized in that the dedusted granules are wetted with 1 % water. 4 * A process for the preparation of non-dusting abrasion-resistant potash fertilizer granules according to item 1, characterized in that the granules are dried to residual moisture content of o, 1 - o, 2% 5 · A process for the preparation of non-dusting abrasion-resistant potash fertilizer granules according to item 1, characterized in that after or parallel to the water treatment, a conditioning with organic substances - preferably mineral oil - is made.