RU2357943C2 - Method of granular potassium fertiliser production - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: method of granular potassium fertiliser production involves mixing fine-grain potassium chloride with a binding agent in a mixer, following balling in a drum granulator, drying and classification. The binding agent is water emulsions of carbamideformaldehyde resins and lignosulphates or polyacrylamide with the ratio of components equal to 1 : 1 - 2 and 1 : 0.017 - 0.02 respectively in the amount of 0.2-1.0% of the potassium chloride weight. Moisture content of the batch supplied for granulating amounts to 7-15%. The method is characterised by increased output of granules of commercial sixe (-4 +2 mm) - more than 60% - having high mechanical strength (4.2-4.6 MPA).

EFFECT: increasing output of commercial fraction and improving strength of granules.

2 cl, 3 ex, 1 tbl

Description

The invention relates to a technology for processing sylvinites by flotation and galurgic methods. It can be used in potash enterprises associated with the production of granular fertilizers and the resulting fine and dusty product fractions that impair the physical and mechanical properties of the marketable product.

In the process of ore mining, crushing, classification and subsequent processing, finely dispersed fractions (-0.25 mm) are formed, the content of which after drying is up to 30% or more. When drying in drum dryers or fluidized bed furnaces, these fractions are removed with flue gases and, when dry cleaned, are trapped in cyclones.

In order not to reduce the degree of extraction of the useful component from the ore, these fractions are mixed with the main product and granulated.

To improve the quality of the obtained granules of potassium chloride using chemical methods.

A known method of producing granular potassium fertilizer by granulation of fine-grained potassium salt in the presence of additives. The binders used are lime, water glass, sodium and calcium phosphates, chloride and sulfate salts of copper, iron, zinc, aluminum and / or high molecular weight organic compounds, for example carboxymethyl cellulose, polyacrylamide (PAA), starch, salts of humic acids, urea-formaldehyde resin , sulphite-bardic concentrate [1].

The disadvantage of this method is the low content of potassium chloride in the granules of a commercial product due to the use of a significant amount of halopelite sludge in the binder.

A known method of producing granular potassium chloride by mixing the finely crystalline salt of the latter with a binder liquid, which is a solution of sulphite-yeast mash (SDB) and potassium chloride (5-30%). Then the resulting mixture was granulated and dried. The total consumption of SDB is 1-5% by weight of fertilizer [2].

The disadvantages of this method are the increased consumption of the binder, as well as the low yield of granules of commodity size (-4) - (+ 2 mm), which necessitates the repeated granulation of significant quantities of products.

A known method of producing agglomerated potassium chloride from finely dispersed potassium chloride, comprising introducing cyclone dust into the wet concentrate captured in the dry flue gas cleaning stage of the drying apparatus and an agglomeration reagent, mixing the mixture and drying it in the drying apparatus. Sodium and ammonium phosphates and sulfates are introduced as an agglomerating reagent, which react with potassium chloride to form double salts. Before drying, the mixture is passed through a turbopaste mixer-granulator to homogenize the mixture according to the particle size distribution, humidity, mechanical activation of KCl particles to obtain granules, the latter are fed to a vibration former for compaction and pelletizing [3].

The method is characterized by a high consumption of agglomerating reagent (5% per ton of absolutely dry potassium chloride).

The closest in technical essence and the achieved result to the present invention is a method for producing granular potassium chloride, comprising pre-mixing dry fine crystalline potassium chloride with 0.5-10% of the estimated amount of sulphite-yeast mash, taken in the form of 0.5-5.0% solution in a twin-shaft screw mixer. The humidity of the mixture should be 1.0-5.0%. In the second stage, the moistened material is fed into a drum or plate granulator, where it is mixed with the remaining amount of sulphite-yeast mash, having a concentration of 10.0-30.0% and fed by means of a nozzle, and the mixture is granulated. The obtained granules are dried in a tumble dryer at 250 ° C and classified by size. Commodity fraction (-4) - (+ 1 mm) is sent to the warehouse, and large and small granules are returned to the production cycle [4] - prototype.

The disadvantage of this method is the low yield of granules of commodity size (-4) - (+ 2 mm), which necessitates repeated granulation of large quantities of feedstock. In addition, the increased consumption of the binder does not provide high strength granules of the commodity product due to the low binding ability of the reagent.

The problem solved by this invention is to increase the yield of product fraction and increase the strength of the granules.

The problem is achieved by the method of producing granular potassium fertilizer by mixing fine-grained potassium chloride with a binder in a mixer, subsequent rolling in a drum granulator, drying and classification. As a binder, aqueous emulsions of urea-formaldehyde resins (CFS) and lignosulfonates (LS) or polyacrylamide are used with a component ratio of 1: 1-2 and 1: 0.017-0.02, respectively, in an amount of 0.2-1.0% by weight of potassium chloride. In this case, the moisture content of the mixture supplied to the granulation should be 7-15%.

Aqueous emulsions based on urea-formaldehyde resins and lignosulfonates or polyacrylamide are characterized by high binding properties. The components of the emulsion contain functional groups capable of interacting under certain conditions with each other and with the surface of KC1 particles with the formation of a polymer skeleton having high strength characteristics.

The optimal ratio of components in polymer complexes is determined by the conditions for the production of granules of high strength.

Urea-formaldehyde resins and lignosulfonates at a component ratio of 1: 1-2 form a polymer complex with maximum strength of the spatial structure and maximum stability in the salt medium. When the resin content is above optimal values, the processes of its polycondensation are enhanced, leading to a decrease in the solubility of the resulting complex, and, as a result, to a decrease in the wetting ability of its aqueous solutions. With an excess of lignosulfonates, the reactivity of the binder decreases, which affects the strength properties of the finished product.

For a polymer complex based on aminoaldehyde resin and polyacrylamide, the optimal component ratios are 1: 0.017-0.02. When the PAA content is above the optimal values, due to the salting out action of KCl on PAA macromolecules, the wetting ability of the binder decreases, which leads to a deterioration in the mixing mode and subsequent rolling. When the content of polyacrylamide is less than optimal values, the binding properties of the reagent are reduced due to an insufficient amount of polycomplex; the strength of such granules is 3.2 MPa.

The choice of binder consumption (0.2-1.0% by weight of the granulated material) is dictated by the need to achieve maximum effect when granulating potassium chloride. A decrease in binder consumption of less than 0.2% leads to an uneven distribution of the binder in the mass of the mixture, which affects the subsequent process of rolling (low yield of product fraction); an increase of over 1.0% does not provide additional benefits and is associated with an increase in reagent consumption and at the same time leads to a decrease in the KCl content in the finished product, which is regulated.

Effective pelletizing of fine-grained potassium chloride proceeds at a charge moisture of 7-15%. At a humidity of less than 7%, due to the uneven distribution of moisture in the mass of the charge, a significant part of the fine-grained particles does not roll out (yield of the commercial fraction is 17.8%). Overmoistening of the mixture over 15% leads to the formation of large granules, increasing the unevenness of the granulometric composition of the finished product.

The proposed method is as follows.

Fine-grained potassium chloride is fed to the mixer, where it is processed using irrigation nozzles with an aqueous emulsion of a binder, the flow rate of which is 0.2-1.0 wt.% Of the load on the mixer. After mixing, the mixture is fed into a drum granulator and is rolled. The obtained granules are dried in a drying drum at a temperature of 110-120 ° C and are classified by size. Large particles (+4 mm) are crushed and with particles less than 2 mm are returned to the production cycle, commodity fraction (-4) - (+ 2 mm) is sent to the finished goods warehouse.

Known example (prototype)

1000 kg of fine-grained potassium chloride is fed into the mixer and mixed with 0.5% of the estimated amount of sulphite-yeast mash (SDB 0.05 kg), taken in the form of a 0.5% solution, to a moisture content of 10%.

The resulting material (1010 kg) is fed into a drum granulator, where it is mixed with the remaining amount of sulphite-yeast mash, fed through the nozzle in the form of a 10% solution, and granulated. The granules are dried at a temperature of 250 ° C.

In the table in examples No. 1-3, the total amount of binder (SDB) varies from 1.0 to 2.7 wt.%. The output granules of the commercial fraction (-4) - (+ 2 mm) is 170-500 kg, respectively.

An example of the method

1000 kg of fine-grained potassium chloride is fed into the mixer and mixed with an aqueous emulsion of a binder containing 3.75 kg of urea-formaldehyde resin (CFS) and 3.75 kg of lignosulfonates (LS) (1: 1) at the rate of 0.75% of the load on the mixer and rolls around in a drum granulator. The obtained granules are dried in a drying drum at a temperature of 120 ° C. The yield of product fraction (-4) - (+ 2 mm) of the finished product is 600 kg.

Example 2 of the method

1000 kg of fine-grained potassium chloride is fed into the mixer and mixed with an aqueous emulsion of a binder containing 7.35 kg of urea-formaldehyde resin (CFS) and 0.15 kg of polyacrylamide (PAA) (1: 0.020) based on 0.75% of the load on the mixer, and rolls around in a drum granulator. The obtained granules are dried in a drying drum at a temperature of 120 ° C. The yield of product fraction (-4) - (+ 2 mm) of the finished product is 601 kg.

Other examples of the implementation of the granulation process are similar to examples 1 and 2. The results of experiments to obtain granular potassium fertilizer by the proposed method are shown in the table.

Physico-mechanical properties of granular potash fertilizer Example No. Name of binder Ratio of components
binder The consumption of the binder, wt.% The moisture content of the mixture,% The output of the commercial fraction (-4) - (+ 2 mm),% The strength of the granules, MPa one
2
3 Sulphite-yeast mash prototype
- ”-
- ”- -
- 1,0
1.8
2.7 10
10
10 17.0
25.1
50,0 2.1
2.5
2.9 four
5
6
7
8 Urea-formaldehyde resin + lignosulfonates
- ”-
- ”-
- ”-
- ”- 1: 0.25
1: 0.50
1: 1
1: 2
1: 4 0.75
- ”-
- ”-
- ”-
- ”- 12
- ”-
- ”-
- ”-
- ”- 30,2
41.1
60.0
48.1
38,2 2.1
3.2
4,5
4.0
2.5 9
10
eleven
12
13
fourteen - ”-
- ”-
- ”-
- ”-
- ”-
- ”- 1: 1
- ”-
- ”-
- ”-
- ”-
- ”- 0.1
0.2
0.5
0.75
1,0
1,1 12
- ”-
- ”-
- ”-
- ”-
- ”- 9.8
36.8
46.7
60.0
61,4
56.1 2.7
3,5
4.2
4,5
4.6
4.6 fifteen
16
17
eighteen
19
twenty - ”-
- ”-
- ”-
- ”-
- ”-
- ”- 1: 1 0.75 6
7
9
12
fifteen
16 17.8
34.7
57.6
60.0
41.3
15.4 2.7
4.0
4.4
4,5
four
3.2 21
22
23
24
25 Urea-formaldehyde resin + polyacrylamide
- ”-
- ”-
- ”-
- ”- 1: 0.013
1: 0.017
1: 0,020
1: 0,025
1: 0,033 0.75
- ”-
- ”-
- ”-
- ”- 12
- ”-
- ”-
- ”-
- ”- 37,2
48.3
60.1
50.9
49.7 3.2
3.8
4.2
3.2
2.7

The results of the experiments shown in the table show that when implementing the granulation process according to the proposed method, an increase in the yield of granules of the commercial fraction from 50% to 60.0-61.4% is achieved. The use of a water emulsion based on a urea-formaldehyde resin and lignosulfonates or polyacrylamide as a binder helps to increase the strength of granules from 2.9 to 4.2-4.6 MPa with significantly lower binder costs of 0.75-1.0 wt.%.

Bibliographic sources

1. A.S. 648555 USSR, IPC ² C05D 1/04; B01J 2/28. A method of obtaining granular potash fertilizers.

2. A.S. 952830 USSR, IPC ² C05D 1/02. A method of obtaining granular potassium chloride.

3. Patent 2213078 of the Russian Federation, IPC ⁷ C05D 1/02, C01D 3/04. A method of producing agglomerated potassium chloride.

4. A.S. 1068409 USSR, IPC ³ C05D 1/02; B01J 2/28. A method of obtaining granular potassium chloride. - The prototype.

Claims (2)

1. A method of producing granular potassium fertilizer by mixing fine-grained potassium chloride with a binder in a mixer, characterized in that water emulsions of urea-formaldehyde resins and lignosulfonates or polyacrylamide are used as a binder in the ratio of components 1: 1-2 and 1: 0.017-0.02, respectively in an amount of 0.2-1.0% by weight of potassium chloride, followed by rolling in a drum granulator. 2. The method according to claim 1, characterized in that the mixing of fine-grained potassium chloride with a binder lead to a moisture content of granulated material of 7-15%.