PL241460B1 - Composition of granular multi-component fertilizer - Google Patents

Abstract

The present invention relates to a granular compound fertilizer composition comprising polyhalite and a fertilizer granule solubiliser, the solubiliser being nitrogen fertilizer, and the composition containing no binding ingredients. The invention also relates to a method of granulating a fertilising composition according to the invention.

Description

Description of the invention

The subject of the invention is a composition of a granulated multi-ingredient fertilizer containing polyhalite as a source of potassium, magnesium, calcium and sulfur, and nitrogen in the form of ammonium or nitrate and amide nitrogen. The invention also relates to a method for producing a granular composition.

From the international patent application No. WO 2020064036, a fertilizer in the form of spherical granules, based on urea and calcined polyhalite, is known. This application also discloses a method for producing fertilizer granules consisting of polyhalite and urea, which consists in agglomerating (granulating) a mixture of polyhalite and urea with the addition of water. The present invention is distinguished from the invention disclosed in WO 2020064036 by the type of polyhalite used. Obtaining the calcined polyhalite used in WO 2020064036 to achieve similar fertilizer properties is time consuming and expensive, and the polyhalite used differs in mineralogical and oxide composition. The present invention differs from the invention disclosed in WO 2020064036 also by the type of granulation used. In the method of the present invention, disc granulation was used, while in the method of WO 2020064036, mixer granulation was used, with which different sizes of granules are obtained.

From the Polish patent application No. P-433510, a composition of a multi-ingredient fertilizer is known, containing polyhalite as the main ingredient. Another, additional component of this fertilizer is also potassium salt, and the filler is carbonate products in the form of meal, which cause faster disintegration of fertilizer granules. This mixture contains basic nutrients for plants, such as calcium, magnesium, potassium, sulfur and sodium. The fertilizing composition is also in the form of granules of spherical shape having identical chemical composition.

Patent No. PL/EP2578557 discloses a composition of a water-soluble NPK multi-component fertilizer containing a mixed salt of ammonium-potassium nitrate with the formula (NH4)xKy(NO3)z, where x = 0.75, y = 0.25, and z = 1.00. This mixture contains three basic elements - nitrogen, phosphorus and potassium, necessary for plant growth. The fertilizer composition disclosed in this publication is characterized in that it is obtained by reacting phosphoric acid, nitric acid with potassium hydroxide and ammonia and is in the form of crystalline granules of spherical shape, each granule having an identical chemical composition.

Other methods of producing compound fertilizers are also known, in which potassium chloride is the source of potassium. The publications GB876565 and GB300919 describe the methods of removing chlorine and nitrosyl chloride from the fertilizer, because, according to world standards, their presence in the fertilizer, even in small amounts, makes it impossible to use it. In Poland and the European Union, appropriate concentrations of chlorine are allowed for agriculture for individual types of fertilizers, and their amount is regulated by Regulation (EC) No. 2003/2003 of the European Parliament and of the Council of October 13, 2003 on fertilizers.

The preferred source of ingredients used in fertilizers are naturally occurring minerals. So far, fertilizers with different degrees of fragmentation of pure raw material have been produced. Most often, minerals were ground into fractions of 100-6000 μm, granulated, and larger fractions were encapsulated with smaller fractions using water or natural adhesive resins and other binders. Insoluble fertilizers with fractions above 200 μm are much more difficult to react with soil acids in the soil. Mineral fractions above 500 μm do not react with soil acids, so fertilization has no effect (this applies only to carbonates and other water-insoluble minerals). This is particularly problematic in drought-affected areas where the solubility of the fertilizers used is negligible.

A significant problem is also the use of binding agents in granulated fertilizers, such as starch, bentonite, lignosulfonates, molasses, calcium hydroxide, bitumen, clay, acids (nitric, hydrochloric, phosphoric, sulfuric), cellulose gum, sucrose, water glass, cements, ashes volatile, volcanic and wood, potassium and sodium silicate, MgO, CaO, alganite, PEG, kaolinite geopolymers, oils, waxes and the like, or their combinations, which on the one hand facilitate the granulation process, but on the other hand hinder the process of disintegration of fertilizer granules during its use, thus limiting the availability of nutrients contained in fertilizers. This is of particular importance when fertilizers are applied in low rainfall conditions.

The aim of the present invention is to provide a fertilizer composition without the addition of binders, thanks to which the granules of the composition dissolve more easily and, consequently, soak into the soil faster.

PL 241 460 B1

Another object of the invention is to provide a method for producing a fertilizer composition from micronized mineral or mineral and organic material.

The composition of the multi-ingredient fertilizer in the form of granules according to the invention contains from 50 wt. up to 82.5% by weight % of micronized polyhalite, based on the total weight of the composition, and from 17.5 wt. up to 50% by weight nitrogen fertilizer, based on the total weight of the composition, as a dissolution agent for the fertilizer granules, the nitrogen fertilizer being preferably ammonium or nitrate nitrogen, and more preferably amide (urea) nitrogen. Also preferably, the source of nitrogen used in the composition according to the invention is selected from urea, nitrates and saltpeter.

The composition according to the invention preferably contains a nitrogen fertilizer in micronized form with a particle size of <200 μm, more preferably <100 μm.

The subject of the invention is therefore a composition of a compound fertilizer in the form of granules, comprising polyhalite, wherein the composition contains an agent that facilitates the dissolution of fertilizer granules, which is a nitrogen fertilizer, and wherein the composition does not contain any binders.

A binder for the purposes of the present invention is any ingredient known in the art used to facilitate the granulation process, such as starch, bentonite, lignosulfonates, molasses, calcium hydroxide, bitumen, clay, acids (nitric, hydrochloric, phosphoric, sulfuric), cellulose gum, sucrose , water glass, cements, fly ashes, volcanic and wood ashes, potassium and sodium silicate, MgO, CaO, alganite, PEG, kaolinite geopolymers, oils, waxes and the like, or combinations thereof.

Preferably, the agent facilitating the dissolution of the fertilizer granules is a nitrogen fertilizer containing nitrogen in the form of ammonium or nitrate and amide nitrogen.

Preferably, the nitrogen fertilizer is selected from urea, saltpeter or nitrates.

The nitrogen fertilizer is present in the composition in an amount of 17.5 to 50% by weight. based on the total weight of the composition.

Preferably, total nitrogen is present in the composition in an amount of from 8 to 23% based on the content of other elements in the present composition.

The polyhalite is present in the composition in an amount of from 50 to 82.5% by weight. based on the total weight of the composition.

Preferably, the nitrogen fertilizer is present in the composition in micronized form with a particle size of <200 Pm, more preferably <100 Pm, or in liquid form.

The subject matter of the invention is also a method of producing the fertilizer composition according to the invention, which includes the following steps:

a) delivery of granulated nitrogen fertilizers in the amount of 17.5% by weight up to 50% by weight based on the total final weight of the composition;

b) milling the granulated nitrogen fertilizers into finer fractions to produce a micronized meal with a particle size of <200 μm, more preferably <100 μm;

c) transferring the micronized meal to a disc granulator;

d) providing micronized polyhalite in an amount of from 50 wt. up to 82.5% by weight based on the total final weight of the composition;

e) mixing the micronized polyhalite with water in a conditioner to form a partially granulated polyhalite;

f) mixing and granulating with water on a disk granulator ground nitrogen fertilizers with partially granulated polyhalite, producing a wet granulate with a granule size of 1-10 mm;

g) cooling and drying the wet granulate to produce a dry granulate with a moisture content of less than 4%;

h) separation of the dry granulate on the separator into the undersize fraction <2 mm, the desired specific fraction 2-6 mm and the oversize fraction >6 mm.

In an embodiment, the composition of the compound fertilizer in the form of granules consists solely of polyhalite and a dissolving agent for fertilizer granules, the dissolving agent being a nitrogen fertilizer such as urea, saltpeter or nitrates.

The source of nitrogen in the form of nitrogen fertilizers (e.g. urea, saltpeter, nitrates) is used only as a means that positively affects the rapid solubility of granulated fertilizer under the influence of even low humidity (dew). This allows the fertilizer to work even in conditions of temporary drought or reduced rainfall and in places where rainfall is relatively rare.

PL 241 460 B1

The above fertilizer mix provides plants with valuable nutrients necessary for proper development and growth, such as nitrogen, sulfur, potassium, calcium, magnesium and sodium. This fertilizer is characterized by a differentiated content of the main nutrients, depending on the amount of the nitrogen-containing component used in the total mixture. This has a positive effect on the possibility of producing different fertilizer compositions, composed of the same substrates, but in different weight ratios, which makes it possible to produce fertilizer mixtures adapted to the needs of different species of crops by optimizing (changing) the chemical composition.

In the case of nitrogen fertilizers, there are many varieties and types, depending on how products are obtained in multi-stage and complex chemical processes. All groups of nitrogen fertilizers are very popular fertilizing agents. However, the solubility parameters of the obtained fertilizer and the type of nitrogen fertilizer are important; mineral or organic. DETAILED DESCRIPTION OF THE INVENTION

Polyhalite is a naturally occurring mineral containing hydrated potassium, magnesium and calcium sulfate, represented by the formula K2MgCa2[SO4]4 • 2H2O, mined more than 1,000 meters below the level of the North Sea. The largest deposits of this raw material are located in Great Britain and only in this place in the world is the process of extracting this mineral taking place. The extracted raw material is crushed into a fraction of 100-10,000 μm.

Nitrogen is the basic component of air, constituting almost 80% of its volume. It plays a very important role in biology because it is part of many biomolecules, such as amino acids and proteins. Plants are able to absorb this element in the form of compounds such as nitrates, nitrites and ammonium salts. Plants absorb nitrogen directly from the soil in the mineral form: ammonium (NH4+) and nitrate (NO3 ^- ). In order for the organic form, i.e. the amide (NH2), to be absorbed by the roots, it must be hydrolyzed in the substrate beforehand. This process, depending on the temperature and humidity, usually takes several or several days. Nitrogen is very necessary for plants in the growth phase, because it is quickly absorbed. With nitrogen deficiency, plants grow slower and their coloration is less intense. Excess nitrogen is dangerous for plants when there is a shortage of water or potassium and phosphorus. It manifests itself, among others, in the reduction of the thickness of the leaf blade, which makes it less resistant to pathogens and environmental factors, as well as in a decrease in the quality of the crop. Therefore, the above mixture described in this application contains potassium and trace amounts of phosphorus to reduce possible risks to plants.

The most important parameter of all fertilizers that determines their speed of action and chemical activity is reactivity. In other words, it is the rate at which the fertilizer reacts with soil acids. This parameter determines, among other things, the dissolution time of granules and the rate of assimilation of nutrients by plants. An important parameter is also the fragmentation of the raw material, which does not dissolve in water or dissolves slowly in it. Such a raw material should be finely divided preferably below 200 Pm and more preferably below 100 Pm. The more fragmented the raw material is, the better results can be obtained by using a smaller dose of fertilizer. This relationship makes fertilizers with extremely finely divided raw materials more effective and less of them can be used, obtaining a similar effect as with larger amounts of poorly divided fertilizers. The screening parameter of a fertilizer substance is a key tool to compare the quality of a fertilizer with similar chemical properties.

The use of polyhalite as the main component of granulated fertilizer enriches the soil with valuable nutrients for plants, such as sulfur, potassium, calcium, magnesium and sodium. Mixtures of a fragmented source of nitrogen, available in a granular form in nitrogen fertilizers, which can act as a catalyst for the dissolution of fertilizer granules with polyhalite, change the content of macroelements in the fertilizer, thanks to which it can be adapted to the needs of individual groups of plants, especially those depleted in nitrogen and other macroelements, which make up polyhalite.

A mixture of ground polyhalite with ground nitrogen-containing fertilizers (nitrogen fertilizers dissolve quickly in water), suitable for use on all types of soil (except those with extremely acid and alkaline soil pH) and for all crops, except for those particularly sensitive to high nitrogen content. The nitrogen concentration will depend on the amount of nitrogen fertilizer, e.g. urea, added to the fertilization mixture.

The process of creating granules consists in agglomeration of particles into fertilizer granules with a final granule size of 2 mm to 10 mm. Granulation is most often done using disc granulators in the wet granulation process, using only water, without any other means

PL 241 460 B1 binding. The essence of such granulation is the efficient obtaining of granulate of the desired fraction, without the participation of the dusty fraction.

The larger the particle size of the raw material (in this case, polyhalite), the slower, more difficult or non-existent will be the granulation process. The experiments show that the nitrogen fertilizer can be crushed and mixed with polyhalite flour or dissolved in water used for polyhalite granulation. The effect of polyhalite as a fertilizer is enhanced by the addition of an agent facilitating the perfect solubility of granules, i.e. nitrogen fertilizer, when it is important to quickly release nutrients to the soil, especially during periodic drought. The solubility of the fertilizer composition is also visible during the guttation or retting process.

According to the present invention, nitrogen fertilizers added to the fertilizer cause faster dissolution of the granules of the fertilizer composition during the application of the fertilizer, and at the same time partially act as a binder for the granules when polyhalite is used in the granulation method.

EXAMPLES

EXAMPLE 1 - Fertilizer composition

Fertilizer compositions made of polyhalite with urea with different contents of starting components were produced. The specific compositions of the prepared fertilizers are indicated in Table 1, below.

Table 1 Exemplary weight proportions of the fertilizer composition according to the invention with urea

Weight proportions of fertilizer components Fertilizer ingredients [%] polyhalite Urea n total K2O CaO MgO Sch Na2O cl 50 50 23 7 8.5 3 24 2 2 67 33 15 9 11 3.5 32 2.5 2.5 74 26 12 10 12.5 4 35.5 3 3 78 22 10 11 13 4.5 37 3 3 82.5 17.5 8 11.5 14 5 39.5 3.5 3.5

The granulated fertilizer according to the invention has a humidity parameter of less than 3-4% by weight of the mass, and the produced granulate with a fraction in the range of 2-6 mm can be spread with standard agricultural spreaders. The granulation process eliminates the problem of dusting, and the granulation of the fertilizer affects the uniformity of sowing.

The advantage of the fertilizing composition according to the invention is the production of multi-component fertilizer granules from salts - polyhalite, in the presence of nitrogen fertilizers, which during granulation partially act as a binder, and during sowing the fertilizer they facilitate the solubility of granules. During the production process of the fertilizer according to the invention, no binding agents for the particles of the starting components are added.

The nitrogen fertilizer contained in the fertilizer with polyhalite is a catalyst for faster dissolution of the granules under the influence of water. Nitrogen in the form of compounds contained in the present invention increases the rate of action of the fertilizer.

The first phase is the dissolution of the granule under the influence of water. The second phase consists in the release of the main nutrients into the soil, which, under the influence of a moist soil environment, are easily absorbed into it and are very well and easily absorbed by plants.

EXAMPLE 2 - Method of producing a fertilizer composition

From the buffer, granulated nitrogen fertilizers (catalysts of fertilizer granule solubility) with a granule size of 1-3 mm are gravitationally transferred through cell sluices to hammer or ball mills for grinding into finer fractions. The milled nitrogen substances are transported by a conveyor belt to a disk granulator, where they are mixed with polyhalite.

Micronized polyhalite from the silo gets by gravity through the cell locks to the screw conveyor, from where it is transported to the buffers. Then, from the buffers, this mineral gets by gravity through the cell locks to the screw conveyor and goes to the conditioner, where it is mixed with water under the pressure of 8 bar, through three drip nozzles. After leaving the conditioner, the material is partially granulated and goes to the circular plate granulator. On the rotary disc granulator, the raw material is still mixed with water and the smaller agglomeration process takes place

PL 241 460 Β1 particles into granules. Granules with a size of 1-10 mm leave the granulator and wet (water content is about 8% by weight) go to the rotary dryer, where the product is dried. The pellets are then cooled in a cold room to a moisture content of <4% or <3%. The dry granulate goes to the separator, where it is divided into fractions: subgrain <2 mm, proper 2-6 mm and overgrain >6 mm. The oversized and undersized fraction of the granulate is returned to the process. The dry product with the wrong fractions is ground in a recycling mill and, through a conveyor belt, goes to a disc granulator. Granulate with the correct fraction is separated from other fractions. In the further course of the production process, the product is placed in polyurethane big-bags (500 kg) with a foil insert.

EXAMPLE 3 - Influence of nitrogen fertilizers on the solubility of fertilizer composition granules (according to the present invention)

In this example, the effect of adding nitrogen fertilizers to a compound fertilizer on the solubility of granules of the fertilizer composition was investigated.

For this purpose, the fertilizers described in Example 1 were kept in various humidity conditions and the time after which the granules dissolved was determined. The results of the experiment for granules with the appropriate content of starting ingredients are presented in Table 2.

Table 2 - Disintegration time of fertilizer granules with exemplary proportions of its components

Weight proportions of fertilizer components Environment Extremely Moist [10%] Damp [7-8%] dry [4-5%] Extremely Dry [2-3%] polyhalite Urea Decomposition time of fertilizer granules [days] 50 50 4 10 16 23 67 33 6 13 18 25 74 26 15 19 23 27 78 22 16 22 28 thirty 82.5 17.5 19 24 thirty 33

The table above shows that the addition of nitrogen fertilizers increases the granule's susceptibility to dissolution and it occurs even at relatively low humidity, but then the process becomes longer. The water content in the soil (humidity) has a special influence on the process of faster dissolution of fertilizer granules. The higher the soil moisture, the faster the granule dissolves.

Claims (6)

Patent claims 1. A composition of a compound fertilizer in the form of granules, containing from 50 wt. up to 82.5 wt. % of micronized polyhalite, based on the total weight of the composition, comprising from 17.5 wt. up to 50% by weight nitrogen fertilizer, based on the total weight of the composition, as a dissolution aid for the fertilizer granules. 2. A composition according to claim 1, characterized in that the agent facilitating the dissolution of fertilizer granules is a nitrogen fertilizer containing nitrogen in the form of ammonium nitrogen or nitrate and amide nitrogen. 3. A composition according to claim The method according to claim 1 or 2, characterized in that the nitrogen fertilizer is selected from urea, saltpeter or nitrates. 4. A composition according to one of claims The composition according to any one of claims 1 to 3, wherein the total nitrogen is present in the composition in an amount of 8 to 23% relative to the content of other elements in the present composition. PL 241 460 B1 5. A composition according to one of claims A method according to any of claims 1 to 4, characterized in that the nitrogen fertilizer is present in the composition in micronized form with a particle size of <200 μm, more preferably <100 μm, or in liquid form. 6. A method of producing a fertilizing composition as defined in claim 1. 1, characterized in that it comprises the following steps: a) delivery of granulated nitrogen fertilizers in the amount of 17.5% by weight up to 50% by weight based on the total final weight of the composition; b) milling the granulated nitrogen fertilizers into finer fractions to produce a micronized meal with a particle size of <200 μm, more preferably <100 μm; c) transferring the micronized meal to a disc granulator; d) providing micronized polyhalite in an amount of from 50 wt. up to 82.5 wt. based on the total final weight of the composition; e) mixing the micronized polyhalite with water in a conditioner to form a partially granulated polyhalite; f) mixing and granulating with water on a plate granulator ground nitrogen fertilizers with partially granulated polyhalite, producing a wet granulate with a granule size of 1-10 mm; g) cooling and drying the wet granulate to produce a dry granulate with a moisture content of less than 4%; h) separation of the dry granulate on the separator into the undersize fraction <2 mm, the desired specific fraction 2-6 mm and the oversize fraction >6 mm.