Potassium sulfate enriched sulfur-bentonite pastille fertilizer: composition and production process

Abstract

The present invention relates to a potassium sulfate-enriched sulfur-bentonite fertilizer composition in pastille form, designed to provide a balanced supply of both potassium and sulfur to plants. The composition comprises potassium sulfate (4 to 30 weight percent), molten elemental sulfur (40 to 85 weight percent), and bentonite clay (3 to 20 weight percent), which are combined using a roto-form pastillation process to form uniform, stable pastilles. The potassium sulfate provides an immediate source of potassium, while the elemental sulfur is gradually released through microbial activity in the soil, ensuring a sustained nutrient supply over time. This novel formulation and production method allows scalable, cost-effective manufacturing, making it ideal for large-scale agricultural applications.

Description

Potassium Sulfate Enriched Sulfur-Bentonite Pastille Fertilizer: Composition and Production Process

[0001] The invention relates to the technical field of agricultural fertilizers, specifically to a sulfur-bentonite pastille fertilizer composition enriched with potassium sulfate. It also relates to a production process for manufacturing the disclosed fertilizer composition.

[0002] Sulfur and potassium are essential nutrients for plant growth and are naturally present in soils in various forms. However, deficiencies in these elements have become widespread globally, which can limit agricultural productivity. To address this, various fertilizers have been developed that contain sulfur and potassium, such as potassium sulfate, potassium thiosulfate, and certain natural minerals.

[0003] These conventional fertilizers are typically water-soluble, which makes them prone to leaching when exposed to irrigation or rainfall. The loss of nutrients due to leaching reduces the efficiency of fertilizer applications and may result in environmental concerns such as water contamination. To combat this problem, fertilizers based on elemental sulfur have been developed. Unlike water-soluble fertilizers, elemental sulfur is insoluble in water, which prevents nutrient loss and allows for more controlled and prolonged release of sulfur into the soil.

[0004] Historically, sulfur-based fertilizers have been composed of elemental sulfur mixed with swelling or dispersing materials, such as bentonite clay. When applied to the soil, these fertilizers absorb water and swell, initiating a dispersion process that releases fine sulfur particles. These particles are then metabolized by soil microbes, converting them into forms of sulfur that plants can absorb. While these sulfur-bentonite fertilizers have proven effective in providing sulfur to plants, they are limited to providing a single nutrient—elemental sulfur.

[0005] To overcome this limitation, the present invention proposes a method for producing potassium sulphate-enriched sulfur-bentonite fertilizer. This enhanced fertilizer composition allows for the gradual release of both sulfur and potassium to crops throughout the growing season. Existing sulfur and potassium-based fertilizers face challenges such as low potassium content and complicated production processes, which are often difficult to industrialize on scale.

[0006] In this invention, a process is introduced to produce an enriched sulfur-bentonite composition that includes potassium sulfate. Upon application to the soil, the fertilizer swells due to the presence of bentonite clay. Initially, potassium ions and sulfate ions from the potassium sulfate are available for immediate uptake by plants. Over time, the elemental sulfur particles are metabolized by soil microbes, gradually converting them into plant-available forms of sulfur. This dual-action approach ensures that both nutrients—potassium and sulfur are supplied to the plants in a timely and efficient manner.

[0007] It is important to note that the release rates of elemental sulfur, sulfate sulfur, and potassium differ significantly. Elemental sulfur is released more slowly, while potassium sulfate provides an immediate source of potassium for plant uptake. This slow and controlled release of sulfur ensures that the two nutrients do not act synergistically in the soil at the same time, which would otherwise result in imbalanced nutrient availability. As a result, the invention aims to create a balanced release of sulfur and potassium throughout the crop's growing season, allowing for sustained nutrient supply over time.

[0008] The objective of the present invention is to provide an enriched sulfur-bentonite fertilizer that supplies both sulfur and potassium nutrients in a single application. The invention also presents a method for producing this fertilizer in a commercially scalable process, ensuring that the production of the fertilizer is straightforward, cost-effective, and suitable for large-scale industrial use. The resulting fertilizer composition is both efficient and practical for modern agricultural practices.

[0009] As is well-known, sulfur bentonite pastille fertilizers produced through the roto-form pastillation process typically have a limited capacity to be enriched with a substantial amount of potassium nutrients. The current production methods are unable to efficiently incorporate potassium from potassium-based sources into the sulfur-bentonite pastille fertilizers. This limitation creates a gap in the market, as there is a strong demand for fertilizers that can provide both sulfur and potassium nutrients in a single, convenient application.

[0010] The present invention addresses this gap by disclosing a novel potassium sulfate-enriched sulfur-bentonite fertilizer composition in pastille form. The composition includes:Potassium sulfate (1 to 300 microns, preferably 1 to 100 microns and more preferably 1 to 70 microns), comprising 4 to 30 weight percent, preferably 10-25 weight percent, and more preferably 17 to 22 weight percent of the composition.Molten elemental sulfur in an amount of 40 to 85 weight percent, preferably 60 to 80 weight percent, and more preferably 65 to 75 weight percent.Bentonite clay is an amount of 3 to 20 weight percent, preferably 7 to15 weight percent, and more preferably 10 to 13 weight percent.

[0011] The disclosed composition allows for the gradual release of both potassium and sulfur to the soil, addressing the dual-nutrient needs of crops. The process used to produce this enriched sulfur-bentonite composition is simple and suitable for commercial-scale production,

[0012] The potassium sulfate present in the composition provides an immediate source of potassium for plants, while the elemental sulfur is released more slowly, allowing both nutrients to be available to the plants at different time intervals. This ensures a sustained and balanced supply of nutrients throughout the growing season. The disclosed process allows for an optimized, cost-effective, and efficient method for producing fertilizers that meet the increasing demand for potassium-enriched sulfur fertilizers.

[0013] The primary technical problem addressed by the present invention is the difficulty in enriching sulfur-bentonite pastille fertilizers with substantial amount potassium nutrients while maintaining the efficiency and integrity of the production process. Most common methods of producing sulfur-bentonite fertilizers in pastille form via roto-form pastillation have not been capable of incorporating substantial amounts of potassium due to various technical and material limitations.

[0014] Specifically, potassium-based sources, such as potassium sulfate, are often challenging to integrate into the pastille matrix, primarily due to their particle size and the complexity of mixing them with molten elemental sulfur without compromising the uniformity and effectiveness of the final fertilizer product. Consequently, existing sulfur-bentonite pastille fertilizers typically do not provide the added value of significant potassium content, which limits their potential applications.

[0015] The present invention provides a solution to the technical problem by introducing a potassium sulfate enriched sulfur-bentonite fertilizer composition in pastille form, which effectively addresses the need for a balanced supply of both sulfur and potassium nutrients for agricultural use. The inventive solution is developed based on the following points:

[0016] Incorporation of potassium sulfate: the invention utilizes potassium sulfate as the potassium source in the sulfur-bentonite composition. By using potassium sulfate with a particle size range of 1 to 300 microns, preferably 1 to 100 microns and more preferably 1 to 70 microns, it ensures that the potassium sulfate is well-dispersed within the sulfur-bentonite matrix. This allows for even distribution of potassium across the fertilizer composition, improving both its efficiency and performance.

[0017] Balanced nutrient release: the composition of the invention provides two distinct nutrient release rates, one for potassium sulfate and one for elemental sulfur. Potassium sulfate provides an immediate and water-soluble source of potassium, which is readily available for plant uptake. On the other hand, elemental sulfur is slow-released due to the action of soil microbes, ensuring that sulfur is available over an extended period.

[0018] Roto-form pastillation process: the invention employs a roto-form pastillation process to produce fertilizer in pastille form. This method ensures uniform mixing of the components potassium sulfate, elemental sulfur, and bentonite clay resulting in stable and homogenous fertilizer pellets. The pastille form improves the handling, storage, and application of the fertilizer, making it easier for farmers to apply to the soil, either as a basal or top-dressing application.

[0019] Commercial-scale production: the developed process is straightforward, scalable, and suitable for commercial production. The simplicity of the process ensures that the enriched fertilizer can be produced at scale, meeting the growing demand for fertilizers that deliver both sulfur and potassium in a single application. The efficient production method also helps to reduce costs, making the final product more accessible to agricultural industries worldwide.

[0020] Minimization of nutrient losses: by combining insoluble sulfur with potassium sulfate in a single fertilizer product, the invention minimizes the potential for nutrient loss. The elemental sulfur component is not prone to leaching like water-soluble fertilizers, ensuring that both sulfur and potassium (as a positively charged cation, potassium will bind to bentonite) are gradually made available to plants over time.

[0021] In summary, the invention solves the problem of limited potassium availability in sulfur-bentonite pastille fertilizers by introducing a novel method for producing a potassium sulfate-enriched sulfur-bentonite composition. This solution offers a balanced, and gradual supply of both sulfur and potassium with a production process that is commercially scalable, cost-effective, and environmentally friendly.

[0022] The potassium sulfate-enriched sulfur-bentonite fertilizer of the invention offers numerous advantages, including:Dual nutrients supply balanced plant nutrition.Gradual nutrient release for improved crop growth.Enhanced nutrient use efficiency and minimized leaching.A scalable, cost-effective, and environmentally friendly production process.

[0023] These benefits make the fertilizer composition an ideal solution for crop production, providing farmers with an effective, and sustainable way to improve crop yields while minimizing environmental impact.

[0024] is an infographic of the process steps for an enriched potassium sulfate composition of sulfur bentonite fertilizer.

[0025] shows a representative image of the pastille form of composition.

[0026] In recent years, the global demand for slow-release sulfur fertilizers for soil application has been growing due to widespread sulfur deficiency, which has led to a reduction in crop yields. It is well established that a lack of sulfur can severely impact both the yield and quality of crops.

[0027] In one embodiment of the present invention, sulfur-bentonite granular fertilizers are of prime importance, and substantial research has been dedicated to developing several types of sulfur-bentonite fertilizers. Elemental sulfur does not leach like sulfates. Instead, small particles of elemental sulfur are gradually converted into sulfate by the action of soil microbes, which supply the sulfur nutrient throughout the growing season.

[0028] In one embodiment of the present invention, the slower release of plant-available sulfur reduces the chances of nutrient loss from the soil. Moreover, elemental sulfur can be beneficial for agriculture due to its multifarious effects, such as fungicidal, insecticidal, miticidal properties, as well as its role as a soil conditioner and pH reducer.

[0029] In another embodiment of the present invention, promoting fertilizers that contain elemental sulfur, such as sulfur-bentonite, and their enriched compositions with significant amounts of macronutrient fertilizer materials, is both beneficial and economical for feeding the soil.

[0030] In one embodiment, in recent years, the deficiency of both potassium and sulfur in the soil has worsened due to the continuous removal of crops and the use of NPK fertilizers containing potassium and sulfur. Leaching and erosion also contribute to sulfur deficiencies. For crops such as oilseeds, potassium and sulfur are essential nutrients for growth and development.

[0031] In one embodiment, potassium is one of the three essential nutrients required by plants. It plays a vital role in all processes necessary for sustaining plant life. Potassium helps crops thrive under water stress by regulating the opening and closing of plant stomata. Furthermore, it contributes to lodging resistance and boosts plants' resilience against insects and diseases. Because of its role in various metabolic pathways that affect crop quality, potassium is often referred to as "the quality element."

[0032] In one embodiment, few efforts have been made in the literature to develop macronutrient-enriched variants of sulfur-bentonite fertilizers. However, these efforts have not utilized significant amounts of macronutrient-based fertilizer materials, which creates a technical challenge in producing cost-effective macronutrient-enriched sulfur-bentonite pastille fertilizers through a roto-form pastillation approach, particularly with respect to the potassium nutrient.

[0033] In one embodiment, all feedstock materials should have low moisture content. Ideally, the moisture content in the mixture is reduced through extended mixing at 135°C, preferably ranging from 0.3 to 1.0 weight percent based on the total weight of the mixture, and more preferably between 0.4 and 0.7 weight percent.

[0034] In one embodiment, the proportions of molten sulfur, bentonite, and potassium sulfate are adjusted to produce a pumpable liquid medium that can easily be used for roto-form pastillation to achieve the desired composition in the final product. To create a potassium sulfate-enriched sulfur-bentonite mixture, the typical ratio of molten sulfur, bentonite, and potassium sulfate is maintained at approximately 70:10:20 weight percent.

[0035] In one embodiment of the present invention, the mixing of molten sulfur, bentonite, and potassium sulfate occurs at atmospheric pressure and within a temperature range of 130°C to 140°C. In this case, the bentonite clay and rock phosphate particles are typically dispersed or suspended within the liquid molten sulfur medium. Ideally, potassium sulfate particles have a particle size 1 to 300 microns, preferably 1 to 100 microns and more preferably 1 to 70 microns.

[0036] In another embodiment, it is preferred that the molten sulfur medium holds dispersed potassium sulfate particles mixed with bentonite clay. The liquid state of the molten sulfur, hereafter referred to as the "mix," encompasses both dispersed bentonite clay and potassium sulfate particles within the molten sulfur medium.

[0037] In one embodiment, the potassium sulfate particles are effectively kept in the dispersion phase by the incorporation of bentonite clay, resulting in a pumpable mixture. Achieving an optimal material balance and particle size of potassium sulfate in the disclosed composition are critical elements of this invention. One benefit of using fine potassium sulfate material is its more uniform distribution throughout the molten sulfur-bentonite liquid medium.

[0038] In a preferred embodiment of the present invention, the direct use of molten sulfur in the disclosed process eliminates the necessity for additional steps, such as remelting elemental sulfur. When elemental sulfur is incorporated in its molten state, the temperature is maintained between 135°C and 140°C.

[0039] In one embodiment, bentonite clay serves as an effective dispersant for mixing with sulfur in a liquid molten phase along with the potassium sulfate material. The bentonite clay is introduced into the molten sulfur in the liquid phase prior to the addition of the potassium sulfate material. The temperature throughout the preparation process is consistently maintained between 135°C and 140°C. The heated mixture is then pumped and subjected to roto-form pastillation to produce the fertilizer.

[0040] In one embodiment, the pastilles derived from the potassium sulfate enriched sulfur-bentonite composition do not require any post-production steps. An optimal size range for the pastilles is between 1.5 to 5.0 mm, with a preferred range of 2.0 to 4.0 mm. The production process encompasses one or more of the steps outlined below.

[0041] In another embodiment, in the first step, molten sulfur (99.9 percent purity) sourced directly from an oil producer company is transferred into a pit or tank, adhering to a specified quantity 40 to 85 weight percent, preferably 60 to 80 weight percent, and more preferably 65 to 75 weight percent with the temperature kept at 130°C to 140°C.

[0042] In another embodiment, in the second step, the temperature of the molten sulfur in the pit or tank is sustained at 130°C to 140°C. Sodium bentonite clay, in an amount of 3 to 20 weight percent, preferably 7 to15 weight percent, and more preferably 10 to 13 weight percent, is then blended with the molten sulfur obtained in the first step. This results in a sulfur-bentonite mixture, which is mixed for 3 to 8 hours under conditions (40 RPM and 135°C) to help disperse the clay within the molten sulfur medium, leading to the formation of a sulfur-bentonite mix.

[0043] In another embodiment, in the third step, potassium sulfate material, with a desired particle size and comprising 4 to 30 weight percent, preferably 10 to 25 weight percent, and more preferably 17 to 22 weight percent is added to the sulfur-bentonite mix formed in the second step. This mixture is then subjected to mixing for 4 to 8 hours under conditions (40 RPM and 135°C) that promote the dispersion of potassium sulfate particles into the molten sulfur-bentonite medium, resulting in a sulfur-bentonite-potassium sulfate blend.

[0044] In another embodiment, in the fourth step, the sulfur-bentonite-potassium sulfate composite mix produced in the third step is pumped and processed through a roto-form pastillator to produce fertilizer with the specified composition and specifications.

[0045] In one embodiment, an enriched pastille form of fertilizer containing sulfur-bentonite compositions includes a substantial amount of fine potassium sulfate.:Examples

[0046] The inventive process includes the following example compositions to further illustrate the method."

[0047] Example 1. (0-0-10+70S)IngredientsQuantity (Kg) required to produce one metric ton productElemental sulphur (99.9 pure in molten form)670 KgSodium bentonite clay130 KgFine Potassium sulpahte (50 percent K2O and 18 percent sulpahte sulphur)200 Kg

[0048] Example 2. (0-0-11+70S)IngredientsQuantity (Kg) required to produce one metric ton productElemental sulphur (99.9 pure in molten form)670 KgSodium bentonite clay120 KgFine Potassium sulpahte (50 percent K2O and 18 percent sulpahte sulphur)220 Kg

[0049] Example 3. (0-0-10+75S)IngredientsQuantity (Kg) required to produce one metric ton productElemental sulphur (99.9 pure in molten form)715 KgSodium bentonite clay85 KgFine Potassium sulpahte (50 percent K2O and 18 percent sulpahte sulphur)200 Kg

[0050] Example 4. (0-0-9+75S)IngredientsQuantity (Kg) required to produce one metric ton productElemental sulphur (99.9 pure in molten form)720 KgSodium bentonite clay100 KgFine Potassium sulpahte (50 percent K2O and 18 percent sulpahte sulphur)180 Kg

[0051] The present invention, which involves a sulfur-bentonite pastille fertilizer enriched with potassium sulfate, offers considerable industrial applicability within the agricultural sector. The disclosed compositions and production process are optimized for large-scale, making it suitable for widespread commercial use. The compositions characteristics promote improved nutrient efficiency, minimize environmental impact, and enhance both crop yield and quality. This invention is especially relevant in regions facing deficiencies of sulfur and potassium, and for crops that rely on both nutrients for optimal growth. Additionally, the production method is designed to be cost-effective and scalable, enabling them to meet the increasing demand for potassium enriched sulphur bentonite fertilizers. The use of roto-form pastillation in the manufacturing process further ensures ease of scalability and efficient industrial production.

Claims

A potassium sulfate-enriched sulfur-bentonite fertilizer composition in pastille form, comprising:Potassium sulfate with a particle size of 1 to 300 microns, preferably 1 to 100 microns, and more preferably 1 to 70 microns, in an amount of 4 to 30 weight percent, preferably 10 to 25 weight percent, and more preferably 17 to 22 weight percent of the composition;Molten elemental sulfur in an amount of 40 to 85 weight percent, preferably 60 to 80 weight percent, and more preferably 65-75 weight percent;Bentonite clay in an amount of 3 to 20 weight percent, preferably 7 to 15 weight percent, and more preferably 10 to 13 weight percent.The fertilizer composition of claim 1, wherein the potassium sulfate provides an immediate and water-soluble source of potassium, and the elemental sulfur is released gradually through microbial activity in the soil.The fertilizer composition of claim 1, wherein the potassium sulfate has a particle size distribution that improves the uniformity of mixing and ensures consistent nutrient release.The fertilizer composition of claim 1, wherein the composition is produced via a roto-form pastillation process, ensuring uniform mixing of potassium sulfate, elemental sulfur, and bentonite clay to form stable and homogeneous pastilles.The fertilizer composition of claim 1, wherein the pastille has a size range of 1.5 to 5.0 mm, preferably 2.0 to 4.0 mm.The fertilizer composition of claim 1, wherein the process for producing the composition comprises the following steps:heating elemental sulfur to a temperature between 130°C to 140°C to form molten sulfur;blending the molten sulfur with bentonite clay to form a sulfur-bentonite mixture;adding potassium sulfate to the sulfur-bentonite mixture and maintaining the mixture at 130°C to 140°C to disperse the potassium sulfate into the sulfur-bentonite matrix;subjecting the mixture to roto-form pastillation to form pastilles.The fertilizer composition of claim 1, wherein the process is scalable for commercial production, providing a cost-effective method for large-scale fertilizer manufacturing.The fertilizer composition of claim 1, wherein the fertilizer composition is applied as a basal or top-dressing fertilizer to improve crop yield and quality.The fertilizer composition of claim 1, wherein the composition is suitable for use in agricultural regions suffering from potassium and sulfur deficiencies.The fertilizer composition of claim 1, wherein the potassium sulfate and elemental sulfur are present in a ratio that maximizes nutrient efficiency and minimizes the environmental impact of the fertilizer.The fertilizer composition of claim 1, wherein the fertilizer is effective for crops such as oilseeds, which require both potassium and sulfur for optimal growth.

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