WO2022256895A1

WO2022256895A1 - A granular fertilizer comprising magnesium and sulfur and method of production

Info

Publication number: WO2022256895A1
Application number: PCT/BR2022/050207
Authority: WO
Inventors: Bruno ORUI SAITO; Carlos Roberto SANT ANA FILHO; Michel CASTELLANI DA ROCHA; Maria Emilia MORAES CASTANHO DE ALMEIDA; Lais SILVESTRE GALVANO; Leonardo Augusto CECCHINI
Original assignee: Icl America Do Sul S. A.; Embrapa Instrumentação
Priority date: 2021-06-09
Filing date: 2022-06-09
Publication date: 2022-12-15

Abstract

Described herein are granular fertilizer comprising magnesium and sulfur and methods of production of such fertilizers. In one embodiment, the granular fertilizer comprises a source of magnesium and a source of sulfur, wherein the source of magnesium comprises one or more fast release forms of magnesium and/or one or more slow release forms of magnesium, wherein the source of sulfur comprises one or more fast release forms of sulfur and/or one or more slow release forms of sulfur. In one embodiment, the method of producing fertilizer granules comprises forming an inorganic fertilizer mixture and pelletizing the mixture to form the granules.

Description

A GRANULAR FERTILIZER COMPRISING MAGNESIUM AND SULFUR AND METHOD OF PRODUCTION

BACKGROUND

Field

The present invention relates to granular fertilizers and methods of producing granular fertilizers, and particularly granular fertilizers comprising magnesium and sulfur.

Description of Related Art

Slow-release fertilizers promote a more homogeneous nutrient distribution in the substrate. They also favor the synchronization between nutrient supply and the physiological demand of the plant, as the rate of nutrient release is directly proportional to temperature, with optimal values close to 21° C, when plants are in full metabolic activity (Oertli, 1980; Perin et al. , 1999). The main disadvantage is their cost. Slow- release fertilizers are more expensive than soluble fertilizers and require rate adjustment in different production systems to optimize input use and ensure the economic production of rootstocks.

Granular fertilizers can be produced in different ways, for example, by compaction or wet granulation. The latter is frequently used when a higher degree of sphericity is desired for the final product, such as shown in U.S. Patent No. 10,519,072, U.S. Patent No. 10,696,604, and U.S. Patent No. 10,865,158.

When a considerable amount of elemental sulfur is used in granule formulation, safety issues on the processing of this material in a conventional wet granulation system must be considered. A granular fertilizer comprising sulfur and magnesium may present a minimum ignition temperature of 200°C, which is much lower than the regular temperature of hot air used to dry granules in the process, generally between 450°C and 750°C. Thus, in this case, the drying temperature must be maintained lower than 200°C to avoid setting fire to the facility.

Processing elemental sulfur powder in the industrial plant is quite difficult. Any spark inside bucket elevators, vibrating screen, cyclones, mills, and bag houses drastically increases the risk of an explosion. Thus, there is a need to find ways to reduce dust formation in the industrial plant to make the process safer.

Wet granulation processes use water to build up the granules and round them. But once the water is added, it must be taken off. A large amount of energy is spent to remove the water after wet granulation. Thus, there is a need to reduce the amount of water used on the processing of the material, thereby reducing the operational cost.

SUMMARY OF THE INVENTION

The present invention is broadly concerned with the production of a granular fertilizer, such as inorganic granular fertilizer. In a particular embodiment, the fertilizer is produced by a pelletizing process. In a particular embodiment, the present invention is concerned with the production of a granular fertilizer comprising magnesium and sulfur. In specific embodiments such production is performed by pelletizing. The objective is to achieve a product with fast and slow release characteristics and improved qualities of traditional granular fertilizers by means of an improved process where safety and operational costs are relevant.

In one embodiment, there is provided a method of producing fertilizer granules. The method comprises forming an inorganic fertilizer mixture and pelletizing the mixture to form the granules. In another embodiment, there is provided a quantity of fertilizer granules formed by the method above.

In one embodiment, the present invention is a granular fertilizer comprising a source of magnesium and a source of sulfur, wherein the source of magnesium comprises one or more fast release forms of magnesium and/or one or more slow release forms of magnesium, wherein the source of sulfur comprises one or more fast release forms of sulfur and/or one or more slow release forms of sulfur. The composition may comprise about 10% w/w to about 20% w/w of magnesium and about 20% w/w to about 40% w/w of sulfur. The magnesium source may be a combination of MgO or MgC03 with Polyhalite and the source of sulfur may be a combination of elemental sulfur with Polyhalite. The fertilizer may further comprise micronutrients as Boron, Copper, Zinc and Manganese. In one embodiment, the present invention is a method of producing fertilizer granules comprising: forming an inorganic fertilizer mixture; and pelletizing the mixture to form the granules. The mixture may comprise less than about 90% by weight water. The inorganic fertilizer mixture comprises magnesium and sulfur. The mixture may comprise about 1% to about 99% by weight of magnesium or a source of magnesium; and about 1 % to about 99% by weight of sulfur or a source of sulfur. The pelletizing may comprise passing the mixture through an extruder and cutting the extruded mixture into pelletized granules. The pelletized granule may comprise less than about 20% by weight water after the extrusion step and/or the cutting step. The method may further comprise rounding the edges of the pelletized granules to form spherical granules. The method may further comprise drying, screening, cooling, and/or storing the granules. The granules may have an average particle dimension of about at least 85% between 2.00 mm (about 10 mesh) to about 4.00 mm (about 5 mesh).

DETAILED DESCRIPTION

Described herein are methods of producing inorganic fertilizer granules, and particularly granules comprising magnesium and/or sulfur, and a granular fertilizer product formed using these methods. The granular fertilizer may also comprise a variety of fertilizer nutrients. However, in certain embodiments, the nutrients include magnesium and/or sulfur. The fertilizer may also comprise one or more other nutrients and/or additives. The methods may include a pelletizing process to form the granules, providing improved safety over traditional compaction processes and/or improved energy efficiency over traditional wet granulation processes. In one or more embodiments, the methods generally comprise forming an inorganic fertilizer mixture, preferably comprising magnesium and/or sulfur. The fertilizer mixture may also comprise other nutrients, additives, and/or liquids. The fertilizer mixture is then pelletized, for example through a pelletizer machine or process, and optionally further processed, to form the fertilizer granules.

The terms fast release and slow release are terms commonly use and known by a person having ordinary skill in the art. The release of nutrients by fertilizers generally means that a nutrient is made available in the soil for uptake. For instance, the term fast release means an immediate supply of the nutrient to the soil, making it immediately available for uptake. On the other hand, the term slow release means a supply of the nutrient to the soil that happens not immediately but through an extended period of time and within the culture cycle.

In one or more particular embodiment, the method comprises forming a fertilizer mixture and feeding the resulting mixture into a pelletizing machine or process. The fertilizer mixture is formed by adding together the raw materials, such as sources of nutrients (e.g., source of sulfur, source of magnesium, source of any other nutrients), additives, and/or liquids (e.g., water), and mixing these materials. In certain embodiments, the materials are added together and mixed to form a substantially homogeneous mixture.

A variety of sources of magnesium may be used. In one or more embodiments, the source of magnesium may comprise one or more fast release forms of magnesium (e.g., magnesium sulfate, magnesium chloride, etc.) and/or one or more slow release forms of magnesium (e.g., magnesium carbonate, magnesium oxide, etc.). Exemplary magnesium sources are described in U.S. Patent No. 9,133,065.

A variety of sources of sulfur may be used. In one or more embodiments, the source of sulfur comprises sulfates, sulfonates, and/or other water-soluble forms of sulfur. In one or more embodiments, the source of sulfur comprises elemental sulfur. In one or more embodiments, the source of sulfur is provided as a water-insoluble solid, which can be gradually oxidized to sulfate by soil microbes, providing a long-lasting supply of useable sulfur to the plants. In one or more embodiments, the source of sulfur is the same as the source of magnesium (e.g., soluble magnesium sulfate and soluble Polyhalite (K2MgCa2(S04)4.2H20) a mineral of natural occurrence with large existing deposits (19%-S and 3.6%-Mg)).

Additional optional nutrients may also be mixed with the magnesium and/or sulfur, including additional micronutrients and/or macronutrients. “Micronutrient” refers to elements typically required in small or trace amounts for plant growth, with preferred micronutrients including nickel, copper, zinc, manganese, boron, iron, cobalt, selenium, molybdenum, chloride, and/or mixtures thereof, and/or sources of the foregoing. “Macronutrient” refers to elements typically required in large quantities for plant growth, with preferred macronutrients including magnesium, sulfur, calcium, phosphorus, potassium, nitrogen, and/or mixtures thereof, and/or sources of the foregoing.

As used herein, a “source” of a macronutrient (including magnesium and/or sulfur) or micronutrient is meant to refer to a compound containing the element (e.g., Cu-EDTA) or the element itself (e.g., Cu), unless stated otherwise.

One or more additives may also be included in the fertilizer mixture, or added during the pelletizing process, so as to provide desired performance advantages. Exemplary additives can include binders, clays (such as montmorillonite), dispersants (i.e. , for improving dispersion of the granules in liquids), polymers, surfactants, lubricants (i.e., for helping the material flow in the process), humic acids and/or a fulvic acids, drying agents, anticaking agents, titanium dioxide, and graphite, although other additives may also be included.

In certain embodiments, the fertilizer mixture comprises about about 1 % to 50 %, about 5 % to 40 %, or about 10 % to 30 % of Magnesium, on a dry weight basis. In certain embodiments, the fertilizer mixture comprises about 1 % to about 95%, about 10% to about 80%, or about 20% to about 40 % of sulfur, on a dry weight basis. In certain embodiments, the fertilizer mixture comprises about 1 % to about 20%, or about 2% to about 10% by weight of one or more additives, on a dry weight basis. In certain embodiments, the mixture comprises a moisture content of less than about 20%, less than about 15%, less than about 12%, less than about 8%, less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1%, less than about 0.5%, or less than about 0.1% by weight, based on the entire weight of the mixture taken as 100% by weight. However, in certain embodiments, the fertilizer mixture may comprise greater levels of moisture. In certain embodiments, moisture may be removed from the mixture before being fed to the pelletizing machine or process, or moisture may be removed during the pelletizing process.

In one or more embodiments, the pelletizing machine or process generally comprises an extruder, wherein the fertilizer mixture is compressed and passed through a die, molding it into the shape of pellets. A quantity of fluid (e.g., water, steam, lubricant etc.) may be added to the mixture in the extruder to assist with mixing, conveying, and/or shaping the mixture. Once the mixture passes through the die, a pelletizer can then cut or otherwise form the extruded mixture into a plurality of substantially uniform-shaped (e.g., cylindrical) pellets. When the fertilizer mixture is fed to the pelletizing machine or process, the granules can be built up with less amount of moisture (e.g., water) than traditional processes (e.g., wet granulation), thereby advantageously reducing the energy needed to dry the granules during production. In certain embodiments, the resulting pellets comprise a moisture content of less than about 20%, less than about 15%, less than about 12%, less than about 8%, less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1 %, less than about 0.5%, or less than about 0.1% by weight, based on the entire weight of the pellets taken as 100% by weight.

In certain embodiments, the pelletized granules (pellets) comprise about 1 % to 50 %, about 5 % to 40 %, or about 10 % to 30 % of Magnesium, on a dry weight basis. In certain embodiments, the fertilizer mixture comprises about 1% to about 95%, about 10% to about 80%, or about 20% to about 40 % of sulfur, on a dry weight basis. In certain embodiments, the fertilizer mixture comprises about 1 % to about 20%, or about 2% to about 10% by weight of one or more additives, on a dry weight basis.

After the pelletizing machine or process, the pellets can then be optionally subjected to one or more processes to prepare a spherical fertilizer granule product. For example, the pellets, which may be in the shape of equilateral cylinders, may be fed to a granulator plate where the edges of the pellets can be rounded (e.g., spheronization). In the case of fertilizers, spherical granules generate less powder that might clog the fertilizer application equipment, and thus spherical granules may be preferred.

The pellets or granules may then be dried. In one or more embodiments, the pellets or granules are fed to a dryer and dried at a temperature of less than about 200°C. As noted above, because of the reduced moisture content of the pellets or granules (as compared to traditional wet milling processes), the energy needed to dry the pellets or granules is greatly reduced.

After drying, the pellets or granules may be screen filtered, cooled, packaged, and/or stored as the granular fertilizer product. In certain embodiments, the pellets or granules have an average particle dimension of about at least 85% between 2.00 mm (about 10 mesh) to about 4.00 mm (about 5 mesh), and preferably about 2.36 mm (about 8 mesh) to about 3.35 mm (about 6 mesh).

The methods described herein have a number of advantages over conventional wet granulation systems. As described above, the use of a pelletizing machine or process between the mixer and the granulator significantly reduces the amount of water used in the granulation, which reduces the energy costs of drying. Moreover, undesirable dust formation is significantly reduced over the whole process as compared to conventional methods.

Additional advantages of the various embodiments of the invention will be apparent to those skilled in the art upon review of the disclosure herein and the working examples below. It will be appreciated that the various embodiments described herein are not necessarily mutually exclusive unless otherwise indicated herein. For example, a feature described or depicted in one embodiment may also be included in other embodiments but is not necessarily included. Thus, the present invention encompasses a variety of combinations and/or integrations of the specific embodiments described herein.

As used herein, the phrase “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing or excluding components A, B, and/or C, the composition can contain or exclude A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

The present description also uses numerical ranges to quantify certain parameters relating to various embodiments of the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range. For example, a disclosed numerical range of about 10 to about 100 provides literal support for a claim reciting “greater than about 10” (with no upper bounds) and a claim reciting “less than about 100” (with no lower bounds). EXAMPLES

The following examples set forth methods and products in accordance with the invention. It is to be understood, however, that these examples are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention.

EXAMPLE I

Extrusion and Pelletization

Lab and pilot tests were conducted using fertilizer mixtures in extruders showing good results. The pilot and/or industrial tests are also being used to build up the granules in a pelletizing machine. Once pellets are formed, pilot and/or industrial testing will begin on spheronization of the pellets.

EXAMPLE II

Granular Fertilizer Composition Comprising Magnesium, Elemental Sulfur, and Clay

In some embodiments, the granular fertilizer comprises a mixture of magnesium (about 15% w/w to about 30% w/w) and sulfur (about 20% w/w to about 40% w/w), with all percentages being by weight and based upon the total product weight taken as 100% by weight.

In other embodiments, the granular magnesium fertilizer comprises magnesium oxide (about 28% w/w to about 60% w/w), elemental sulfur (about 20% w/w to about 42% w/w), high swelling clay such as montmorillonite (about 6% w/w to about 18% w/w), binders (about 2% w/w to about 7% w/w), and lubricants (about 2% w/w to about 20% w/w). As will be appreciated by one of skill in the art, any suitable binder, for example but by no means limited to, sugar, starch, modified starch, lignosulfonates, sugarcane molasses or combinations there, may be used.

In some embodiments, the use of an acid such as but by no means limited to sulfuric acid or phosphoric acid enhances the disintegration of the granules, working in synergy with montmorillonite-type clay. The amount of acid in the final product may not exceed 5% w/w.

In one embodiment, the components of the granular magnesium fertilizer comprise: magnesium oxide (MgO) 48.12% w/w, elemental sulfur 35.38% w/w, calcium lignosulfonate 2.00% w/w, sugar 2.50% w/w, and montmorillonite clay 12.00% w/w.

This product has a high concentration of magnesium (about 15% w/w to about 30% w/w) and sulfur (about 20% w/w to about 40% w/w) and supplies magnesium slowly and gradually.

The addition of high swelling clay enables rapid disintegration of the granule, allowing the soil bacteria to oxidize elemental sulfur to sulfate, which reacts with the magnesium oxide to form magnesium sulfate. It also allows that, after granule disintegration, the finely divided magnesium oxide is available for action of the organic acids produced by the roots of the plants, providing magnesium ions to the plant.

EXAMPLE III

Granular Fertilizer Composition Comprising a mix of Magnesium and Sulfur sources

In some embodiments, the granular fertilizer comprises a mixture of magnesium (about 10% w/w to about 20% w/w) and sulfur (about 20% w/w to about 40% w/w), with all percentages being by weight and based upon the total product weight taken as 100% by weight.

In other embodiments, the granular magnesium fertilizer comprises magnesium oxide (about 5% w/w to about 30% w/w), elemental sulfur (about 10% w/w to about 40% w/w), Polyhalite, as source of both magnesium and sulfur (about 10% w/w to about 75% w/w), high swelling clay such as montmorillonite (about 5% w/w to about 18% w/w), binders (about 2% w/w to about 7% w/w), and lubricants (about 2% w/w to about 20% w/w). As will be appreciated by one of skill in the art, any suitable binder, for example but by no means limited to, sugar, starch, modified starch, lignosulfonates, sugarcane molasses or combinations there, may be used.

This product has a high concentration of magnesium (about 10% w/w to about 20% w/w) and sulfur (about 20% w/w to about 40% w/w) and supplies both magnesium and sulfur gradually, part immediately (Polyhalite) and part slowly (MgO and S°) due the different solubilities and modes of action for each one source.

In this sense, the granular fertilizer comprises a source of magnesium and a source of sulfur. The source of magnesium comprises one or more fast release forms of magnesium and/or one or more slow release forms of magnesium. The source of sulfur comprises one or more fast release forms of sulfur and/or one or more slow release forms of sulfur. One example of fast release form for both sources is Polyhalite. Examples of slow release forms for both sources are MgO and S°.

Claims

1 . A granular fertilizer comprising a source of magnesium and a source of sulfur, wherein the source of magnesium comprises one or more fast release forms of magnesium and/or one or more slow release forms of magnesium, wherein the source of sulfur comprises one or more fast release forms of sulfur and/or one or more slow release forms of sulfur.

2. The granular fertilizer of claim 1 , wherein the composition comprises about 10% w/w to about 20% w/w of magnesium and about 20% w/w to about 40% w/w of sulfur.

3. The granular fertilizer of claim 1 or 2, wherein the magnesium source is a combination of MgO or MgC03 with Polyhalite and the source of sulfur is a combination of elemental sulfur with Polyhalite.

4. The granular fertilizer of claim 1 , wherein the fertilizer further comprises micronutrients as Boron, Copper, Zinc and Manganese.

5. A method of producing fertilizer granules comprising: forming an inorganic fertilizer mixture; and pelletizing the mixture to form the granules.

6. The method of claim 1 , wherein the mixture comprises less than about 90% by weight water.

7. The method of claims 1 or 2, wherein the inorganic fertilizer mixture comprises magnesium and sulfur.

8. The method of claim 3, wherein the mixture comprises: about 1% to about 99% by weight of magnesium or a source of magnesium; and about 1 % to about 99% by weight of sulfur or a source of sulfur.

9. The method of any of the preceding claims, wherein the pelletizing comprises passing the mixture through an extruder and cutting the extruded mixture into pelletized granules.

10. The method of any of claim 5, wherein the pelletized granule comprises less than about 20% by weight water after the extrusion step and/or the cutting step.

11. The method of claims 5 or 6, further comprising rounding the edges of the pelletized granules to form spherical granules.

12. The method of any of claims 5-7, further comprising drying, screening, cooling, and/or storing the granules.

13. The method of any one of the preceding claims, wherein the granules have an average particle dimension of about at least 85% between 2.00 mm (about 10 mesh) to about 4.00 mm (about 5 mesh).

14. A granular fertilizer product formed by the methods of any of the preceding claims.

15. The granular fertilizer of claim 14, wherein the fertilizer is based on Polyhalite.