MICRONIZED SULFUR POWDER

Abstract

A process is provided for producing a micronized sulfur powder product, which includes preparing a micronized sulfur emulsion from molten sulfur and a dispersing solution, which includes a surfactant at a concentration lower than the critical micelle concentration of the surfactant.

Description

MICRONIZED SULFUR POWDER FIELD OF INVENTION This invention relates to a process for processing elemental sulfur from micronized particles. BACKGROUND Elemental sulfur is an essential ingredient in several industrial applications, including fertilizer applications for crops, ammunition manufacturing, and rubber vulcanization. One complication with the use of elemental sulfur particulates in fertilizer applications using the prior art is that when applied to the soil as particles larger than 100 microns, the sulfur reaches the plant roots very slowly. Elemental sulfur is insoluble in water and therefore cannot be absorbed by plant roots. It is converted by microbial action into water-soluble sulfate, which is subsequently readily absorbed by plant roots. Direct application of water-soluble sulfate fertilizers is possible, but absorption suffers from excessive dissolution, as well as uncontrolled release and leaching, thus leading to a low return on investment in agricultural inputs. The conversion of elemental sulfur particles into sulfate-sulfur is considerably more effective when the particles are small, particularly those smaller than approximately 30 microns, a size range commonly referred to as micronized sulfur. When applied to the soil where plants are grown, micronized sulfur can provide nutrients to the plants in the same season of application, and as such, micronized sulfur has value and application in the fertilizer industry. There is also an application for using micronized sulfur in ammunition manufacturing, as finely divided sulfur particles burn more efficiently and are more effective than larger sulfur particles. Using consistently fine-sized micronized sulfur particles in ammunition manufacturing can result in higher-quality and more reliable ammunition. The rubber manufacturing industry in aviation and automobiles also requires large quantities of fine sulfur powder for rubber vulcanization. The reaction between sulfur and rubber results in a very hard and durable material with physical properties that can be described as follows: QQO / nn / Lznz / E / Yii maintains a comparatively wide temperature range. Therefore, the finer the sulfur powder, the better the reaction with the rubber and the higher the quality of the rubber produced. Fine sulfur is also widely used in the latex industry as a vulcanizing agent to provide strength to products. Finer sulfur particles reduce curing time and provide better tensile strength to products such as latex gloves, mattresses, etc. In other applications, the paint industry also uses very fine sulfur powder in color mixing. Micronized sulfur is also widely used as a fungicide, insecticide, and pesticide, and it also has medicinal uses for treating skin diseases in humans. Micronized sulfur powder can be produced by pulverizing sulfur lumps in a crushing machine. Conventional crushing methods require substantial energy consumption, particularly when producing very fine particles. Furthermore, crushing technologies for the production of micronized sulfur powder present fire and explosion risks. Sulfur is a flammable and explosive substance, and mechanical crushing can lead to exposure to the risk of explosion. Therefore, there is a need in the technique for alternative methods to produce micronized sulfur particles. SUMMARY OF THE INVENTION In one aspect, the invention comprises a method for producing micronized sulfur, comprising the steps of: (a) preparing an emulsion of liquid sulfur in an aqueous dispersing solution comprising a surfactant at a concentration below its critical micelle concentration (CMC), and (b) solidifying the liquid sulfur droplets to produce a micronized sulfur suspension. In some formulations, the amount of surfactant can be optimized by measuring the CMC in the solution and determining an optimal surfactant concentration that minimizes particle size and / or particle size variation. The CMC of the surfactant can be measured by measuring its surface tension using standard techniques and equipment known to those skilled in the art. Preferably, the surfactant concentration is less than approximately 75%, 50%, 40%, 30%, or 20% of its CMC. The surfactant may comprise an anionic surfactant or a non-ionic surfactant, such as naphthalene sulfonate or octylphenol ethoxylate. αοο / ηη / ίζηζ / Ε / γι In preferred embodiments, the surfactant concentration is less than approximately 0.75% (by weight). In another aspect, the invention may comprise a micronized sulfur product, wherein the average or median particle size is approximately 5 microns or less, or preferably approximately 3 microns or less. In another aspect, the invention may comprise a micronized sulfur product wherein 95% of the particles are smaller than approximately 12, 10, 9, or 8 microns. In another aspect, the invention may comprise a micronized sulfur powder product dispersed in a solution comprising an aqueous dispersant comprising a surfactant at a concentration below 1.5% (wt.) and below its critical micelle concentration (CMC). In preferred embodiments, the mean or median particle size is less than approximately 5 microns, or less than approximately 3 microns, and the mean or median particle size does not substantially increase during 24 hours, 2, 3, 4, 5, 6, 7, or 30 days of storage. Preferably, the average particle size of the particles within the 50th, 60th, 70th, 80th, 90th, or 95th percentile does not increase substantially over time. In some forms, the product may also include a fertilizer salt, such as urea ammonium nitrate (UAN), ammonium sulfate, ammonium polyphosphate (APP) and / or a herbicide, pesticide or fungicide. In some embodiments, the product is a liquid suspension and further comprises a suspending agent, such as a polysaccharide, such as a substituted or unsubstituted starch, pectate, alginate, carrageenan, gum arabic, guar gum and xanthan gum, or a clay. In preferred embodiments, the suspension does not comprise solubilized sulfur. BRIEF DESCRIPTION OF THE FIGURES Figure 1. Average PSD percentile (P50, pm) of 100 Hz micronized sulfur dispersion produced with various water sources over time (hours). Figure 2. Average lowest percentile PSD (PIO, pm) of micronized sulfur dispersion is 100 Hz produced with various concentrations of Morwet™ over time (days) in demineralized water. οοο / ηη / ίζηζ / Β / γι Figure 3. The average PSD percentile (P50, pm) of a micronized sulfur dispersion is 100 Hz produced with various concentrations of Morwet™ over time (days) in demineralized water. Figure 4. The average upper percentile PSD (P95, pm) of a micronized sulfur dispersion is 100 Hz produced with various concentrations of Morwet™ over time (days) in demineralized water. Figure 5. Average PSD (P50, pm) percentile of micronized sulfur dispersion is 100 Hz produced with various concentrations of Morwet™ over time (days) in demineralized water where all Morwet concentrations increased to 5% on day 4. Figure 6. The average PSD percentile (P50, pm) of a micronized sulfur dispersion is 100 Hz produced with various concentrations of Morwet™ in demineralized water where all 5% Morwet samples from Figure 5 were heated to 80 °C. Figure 7. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 1% over time (hours) in demineralized water. Figure 8. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 1% over time (hours) in tap water. Figure 9. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 1.25% over time (hours) in demineralized water. Figure 10. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 1.5% over time (hours) in demineralized water. Figure 11. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 1.5% over time (hours) in tap water. Figure 12. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 2% over time (hours) in demineralized water. QQO / nn / Lznz / E / Yii Figure 13. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 2% over time (hours) in tap water. Figure 14. The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th, and 95th percentiles of particle size (pm) of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 3% over time (hours) in demineralized water. Figure 15. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 3% over time (hours) in tap water Figure 16. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Morwet™ at 5% over time (hours) in demineralized water. Figure 17. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with 5% Morwet™ over time (hours) in tap water Figure 18. The average PSD percentile (P50, pm) of a micronized sulfur dispersion is 100 Hz that has been stirred or left undisturbed (sedimented) over time (days), without the addition of additional surfactant. Figure 19 shows the mean percentage PSD average (P50, pm) for those samples in which additional Morwet™ was added on Day 4 to the treatments for a total of 5.0%. Figure 20. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion is 100 Hz produced with Triton X-405 at 1% over time (hours) in running tap water. Figure 21. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Triton X-405 at 1.5% over time (hours) in running tap water. Figure 22. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Triton X-405 at 2% over time (hours) in running tap water. Figure 23. Particle size percentiles (pm) 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95 of a micronized sulfur dispersion at 100 Hz produced with Triton X-405 at 5% over time (hours) in running tap water. αοο / ηη / ίζηζ / Ε / γι DETAILED DESCRIPTION OF THE ILLUSTRATED MODALITIES As described in more detail below, the present invention comprises a method for producing a micronized sulfur product. The product consists of very fine sulfur particles having an average particle diameter of between approximately 1 and approximately 7 microns. A basic method for producing micronized sulfur is described in U.S. Patent No. 8,679,446, the full contents of which are incorporated herein by reference, where permitted. In some methods, elemental sulfur is melted and a superheated water dispersion solution is produced separately for later mixing. Molten sulfur can be produced in a heating vessel or in a heating pump using sulfur or another sulfur feedstock above its melting point. This generally requires heating to a temperature of approximately 115°C to 150°C. The specific equipment that can be used to produce molten sulfur will be well known to those skilled in the art, who will use adjusted process parameters to achieve the objective of melting and pumping the sulfur. The dispersant may be an anionic, cationic, amphoteric, or nonionic surfactant, or a combination thereof. The surfactant stabilizes the emulsion of molten liquid sulfur in the dispersing solution during the homogenization process. In some embodiments, the surfactant comprises an anionic surfactant such as naphthalene sulfonate (as Morwet™) or carboxymethylcellulose. Suitable anionic surfactants include, but are not limited to, lignin derivatives such as lignosulfonates, aromatic sulfonates, and aliphatic sulfonates and their condensates, formaldehyde and derivatives, fatty acids / carboxylates, sulfonated fatty acids, and phosphate esters of alkylphenol-, polyalkyleryl-, or alkylalkoxylates. Suitable cationic surfactants include, but are not limited to, nitrogen-containing cationic surfactants. Alternatively, the surfactant may comprise a nonionic surfactant such as an alkylphenol ethoxylate (e.g., octylphenol ethoxylate (Triton™ X-405)). In one embodiment, the dispersant comprises a nonionic surfactant. Suitable nonionic surfactants for use in the present invention include alkoxylated fatty alcohols, alkoxylated fatty acids, alkoxylated fatty ethers, alkoxylated fatty amides, alcohol ethoxylates, nonylphenol ethoxylates, octylphenol ethoxylates, ethoxylated seed oils, ethoxylated mineral oils, alkoxylated alkylphenols, ethoxylated glycerides, castor oil ethoxylates, and mixtures thereof. Although the use of a surfactant as a dispersant is known in the art, modifying the surfactant concentration has been found to have an unexpected effect. The surfactant concentration in the dispersant solution is reported as a weight percent of the dispersant solution and is controlled to be below the critical micelle concentration (CMC), which will vary according to the surfactant and many other parameters, including the water source, the salt concentration of the solution, and the temperature. In preferred embodiments, the surfactant concentration is less than approximately 75%, 50%, 40%, 30%, 20%, or 10% of the CMC. The CMC of a surfactant in solution can be quantified empirically by measuring the surface tension using a tensiometer, as is well known in the art. The CMC is determined as the point where the baseline of minimum surface tension intersects the slope where the surface tension exhibits a linear decline. Surface tension versus logarithmic concentration can be plotted by measuring a series of manually mixed solutions or by using commercially available automated equipment. In some embodiments, the dispersing solution is formed with demineralized water. Demineralized water can be produced by a variety of different methods, including distillation, reverse osmosis, ultrafiltration, deionization with ion-exchange resins, or any other method for purifying water. As used herein, demineralized water is water that is substantially free of dissolved ions, regardless of how it is produced. One method for measuring the purity of demineralized water is by a conductivity test or, conversely, a resistivity test. Demineralized water suitable for this invention shall have a conductivity of less than approximately 100 pS / cm at 20°C, and preferably less than approximately 5.0 pS / cm, and more preferably less than approximately 2.0 pS / cm.In alternative modalities, the dispersing solution is formed with tap water, well water, or any available water source that may have dissolved ions. The dispersing solution is superheated under pressure to a temperature in the range of approximately 115 °C to approximately 150 °C. In practice, a pressure vessel capable of operating in the range of approximately 25 to approximately 80 psig is effective for allowing the heating of a substantially aqueous dispersing solution to a temperature between approximately 115 °C and approximately 150 °C, while keeping the dispersing solution substantially in liquid form. The molten sulfur and the heated dispersant solution can then be mixed in a homogenizer to produce an emulsified sulfur suspension. Any homogenizing equipment 7 Suitable QQO / nn / Lznz / E / Yi can be homogenized using mechanical or fluid cutting means. For example, in one mode, a high-speed rotating mechanical disc homogenizer or a high-pressure pipe atomization emulsification unit can be used. The result of this stage will be the emulsion of molten sulfur in a micronized dispersed phase within the dispersing solution, producing an emulsified sulfur emulsion. By varying the speed of the mixing apparatus, the spacing of the grooves on the mechanical discs, or the size / pressure of the atomizer, the process can be optimized to produce particles of a certain average size, or of a certain maximum or minimum size. After discharge from the emulsification or homogenization equipment, the emulsified sulfur emulsion can be cooled by any suitable means. For example, the emulsion can be cooled in a heat exchanger or similar equipment, evaporating the emulsion at a lower pressure, or simply allowed to cool below the melting point of sulfur. Preferably, the emulsified sulfur slurry is cooled below 100 °C for further processing. Upon cooling, the finely dispersed molten sulfur droplets in the emulsion will solidify, forming micron-sized solid sulfur particles. Without restriction to one theory, it is believed that the concentration of the surfactant has surprising and unexpected effects on the particle size of solidified sulfur. Generally, when surfactants are dispersed in an aqueous solution, they can adsorb at a hydrophobic / hydrophilic interface or self-assemble in a bulk solution. Adsorption is defined as the concentration of surfactants at the interface, while self-assembly is the aggregation of surfactants into micelles. In the sulfur micronization process described above, the surfactant functions, at least in part, to reduce the interfacial tension between the generally insoluble molten sulfur and the water phase. The driving force for surfactant adsorption is the reduction of the phase boundary free energy. As such, surfactant molecules will preferentially assemble at the interface until the concentration reaches a point where the energy required to maintain a surfactant molecule at the surface is no longer favorable. At this point, the surfactants begin to form micelles in solution, and this defines the critical micelle concentration. Elemental sulfur has very low solubility in pure water. However, in the presence of surfactants, the solubility of sulfur increases significantly. With increasing surfactant concentration, micelles form, and the amount of solubilized sulfur increases. It is believed that smaller particles dissolve the fastest. οοο / ηη / ίζηζ / Β / γι To decrease the overall energy of the system, the solubilized sulfur then deposits onto other particles as the suspension cools, causing particle growth and crystallization. Therefore, if the surfactant concentration is increased beyond the CMC during the homogenization process, it is expected that greater particle growth will be observed upon cooling. The CMC is affected by several parameters. Temperature, ionic strength, ion type, and surfactant type are all important factors. In the case of an ionic surfactant, the CMC decreases in the presence of ions. Fully ionized head groups result in a significant amount of electrostatic repulsion between them, hindering micelle formation. However, due to the high electric field strength of these head groups, cations are rapidly adsorbed. This adsorption reduces the electrostatic repulsion between head groups (through shielding) and improves micelle stability at lower CMCs. The critical concentration of salts (CMC) can be increased by adding substances such as urea and formamide. These are known to counteract the harmful effects of high salt concentrations. The addition of chaotropic agents, such as an alcohol, has been found to decrease the CMC. The effects of the CMC are also influenced by the concentration of the chaotropic agent; generally, a higher concentration of the chaotropic agent will result in a decrease in the CMC. Conversely, anticaotropic or cosmotropic agents, such as ammonium sulfate, can increase the CMC. The applicant has discovered that reducing the surfactant concentration can result in smaller and more uniform micronized sulfur particles, averaging 1 to 5 microns. In the applicant's previous work, micronized sulfur particles averaging 7 microns were reliably produced using a naphthalene sulfonate surfactant at a concentration of 1.5% (by weight) in the dispersing solution and tap water. This is believed to be due to limiting the solubility of sulfur during homogenization and reducing particle size growth after solidification. Therefore, in preferred embodiments, the dispersing solution is prepared to a surfactant concentration well below its CMC, but still sufficient to reduce the interfacial tension between the liquid sulfur and water to allow the formation of the micronized emulsion.In practice, this may be less than approximately 75%, 50%, 40%, 30%, 20% or 10% of the CMC. The process water used to prepare the solution can vary in hardness, pH, and conductivity depending on the facility's water source. Ionic strength and ion type have a significant effect on surfactant performance. Consequently, in some embodiments, it is preferable to determine how the process water affects the chosen surfactant and, subsequently, its physical characteristics, primarily the size of the sulfur particles. In some embodiments, the method includes testing the dispersant solution to determine the CMC of the chosen surfactant. For example, it was observed that the particle size of sulfur increases over time when tap water, which contains ions, is used as the water source in the homogenization process compared to when demineralized water is used. The CMC for ionic surfactants in tap water is likely less than 2–3% by weight of surfactant concentration. Above this concentration, the particle size can and does increase after production. The resulting micronized sulfur suspension can be stored for significant periods of time for later incorporation into granular or liquid fertilizer products. The small amount of surfactant (below the CMC value) likely stabilizes the suspension without causing any significant solubilization of the sulfur. Therefore, a suspension of micronized sulfur in which the average or median particle size is approximately 5 microns or less, or preferably approximately 3 microns or less, can be stable during storage. As used herein, a stable suspension is one in which the average particle size does not increase substantially for at least 24 hours, 2, 3, 4, 5, 6, 7, or 30 days. In some embodiments, a preferred stable suspension is one in which the average particle size of particles smaller than the 50th, 60th, 70th, 80th, 90th, or 95th percentile of the particle size distribution does not increase substantially over time. A particle size is considered not to increase substantially if the particle size growth is less than 50%, 40%, 30%, 20%, or 10% of the original size. Micronized sulfur suspension can be mixed with other fertilizer salts, such as urea ammonium nitrate (UAN), ammonium sulfate, ammonium polyphosphate (APP), or other salts, or with various herbicides, pesticides, or fungicides to produce blended fertilizer products, without risk of significant particle size increase for periods of one week to one month or more. If a liquid fertilizer is desired, a suspending agent, such as a polysaccharide (e.g., substituted starches, pectates, alginates, carrageenans, gum arabic, guar gum, and xanthan gum), or a clay, can also be added. QQO / nn / Lznz / E / Yi In some formulations, it is preferable to periodically stir or agitate the micronized sulfur suspension, as this appears to delay the dissolution and deposition of the dissolved sulfur onto the particles, thus increasing particle size. Constant or periodic agitation can serve to delay or eliminate particle size increase after production. Alternatively, the suspension can be processed to produce a cake or powder of micronized sulfur. This can be achieved using readily available equipment to recover or remove the dispersing solution from the emulsified sulfur suspension, such as a filtration device like a mechanical filter, decanter, or centrifuge. The finely dispersed micronized sulfur particles, created during the emulsification process, are thus separated from the dispersing solution. The addition of additional surfactant to the micronized sulfur dispersion after production does not appear to affect the particle size of the micronized sulfur; therefore, in some embodiments, additional surfactant may be used to increase the stability of the dispersion for storage. The addition of various salts, such as 1%-5% brine solution, 1%-5% ammonium sulfate solution, or 1%-5% UAN solution, after the production of micronized sulfur does not appear to affect the average particle size when using an ionic (e.g., Morwet™) or non-ionic (e.g., Triton X-405) surfactant below approximately 5% surfactant in the dispersing solution. EXAMPLES The following examples are provided to illustrate embodiments of the invention and are not intended to limit the claimed invention in any way. Example 1 - Particle size distribution Particle size distributions were determined for micronized sulfur dispersions prepared with different water sources. 1. Micronized sulfur dispersion + 1.5% Morwet™ (% by weight) + demineralized water 2. Micronized sulfur dispersion + 1.5% Morwet™ (% by weight) + tap water For each treatment, a dispersion of micronized sulfur with 1.5% Morwet™ D425 and demineralized tap water or Calgary water (-448 pS / cm) was produced. A sample of the mixture was collected at the pilot plant outlet of the homogenizer, and the particle size distribution (PSD) was monitored for 24 hours using a Microtrac instrument. Each PSD measurement was performed in triplicate, and the PSD is shown as the particle diameter value at 50% of the cumulative distribution (PSD D 50). The PSD data (Figure 1) show that particle sizes were relatively constant during the first 4 hours of monitoring. Thereafter, particle sizes increased for both the demineralized and tap water samples over the course of 24 hours. The tap water sample grew larger than the demineralized sample, suggesting that the ions dissolved in the tap water decrease the CMC of Morwet™. This decrease in CMC results in the dissolution of sulfur during the homogenization process and the subsequent deposition of dissolved sulfur onto existing particles upon cooling, causing a slight increase in size. Example 2: Methods for CMC dispersion of micronized sulfur at various concentrations of Morwet™ The micronized sulfur dispersions that were tested and monitored were the following: QQO / nn / Lznz / E / Yi Surfactant concentration (% by weight of Moewet™) in dispersing solution Water Type 0.5% demineralized 0.75% demineralized 1% demineralized 1.5% demineralized 3.0% demineralized Fresh micronized sulfur dispersion was produced at 100 Hz (peak homogenization rate) with demineralized water to sulfur concentrations of approximately 60% sulfur. This dispersion was collected immediately and tested for particle size distribution (PSD) after production. Samples were further analyzed daily until the particle size stabilized. Once the PSD stabilized, additional Morwet™ was added to the samples to bring the total Morwet™ concentration to 5%. The PSD was monitored daily until it stabilized. Twenty ml samples containing a 5% concentration of Morwet™ were transferred to a hot plate and heated to 80 °C for 2 minutes. The PSD was tested immediately after heating. Figure 2 shows the average lowest percentile PSD (PIO, pm) of a 100 Hz micronized sulfur dispersion produced with various concentrations of Morwet™ over time (days) before the additional surfactant was added. The micronized sulfur dispersion material was produced using fresh micronized sulfur dispersion and demineralized water. Figure 2 shows an increase in particle size in samples with 1.5% and 3% Morwet™ after Day 1, from approximately 0.5 microns to 1.5 microns. The particle sizes of the sample containing less than 1.5% Morwet™ did not change significantly and remained below 0.7 microns, suggesting that the smallest particles did not increase in size. Figure 3 shows the average PSD percentile (P50, pm) of a 100 Hz micronized sulfur dispersion produced with various concentrations of Morwet™ over time (days), before the additional surfactant was added. The micronized sulfur dispersion material was produced using fresh micronized sulfur and demineralized water. Figure 3 shows particle sizes of less than 5 microns for samples containing less than 3% Morwet™ and particle sizes of 20 microns with 3% Morwet™. These data suggest that CMC, which causes significant sulfur dissolution and particle growth, is found between 1.5% and 3% Morwet™ concentration during the homogenization process in demineralized water. Figure 4 shows the average upper percentile PSD (P95, pm) of a 100 Hz micronized sulfur dispersion, produced with various concentrations of Morwet™ over time (days) before the additional surfactant was added. The micronized sulfur dispersion material was produced using fresh micronized sulfur and demineralized water. As shown in Figure 4, significant particle size growth occurred for Morwet™ concentrations above 1.5% during the homogenization process, from 6 microns to 50 microns. It also shows a smaller particle size increase with the 1.5% Morwet™ concentration, from 6 microns to 15 microns. This suggests that at Morwet™ concentrations of 1.5% or higher, particle size growth will occur during the homogenization process. Figure 5 shows the average PSD percentile (P50, pm) of a 100 Hz micronized sulfur dispersion produced with various concentrations of Morwet™ over time (days), using fresh material and demineralized water. The final concentration of Morwet™ was subsequently increased to 5.0% for all samples. No significant change in particle size was observed within 5 days of the increased surfactant addition. To determine if heat plays a significant role in sulfur dissolution, the 5% samples were heated to 80 °C for two minutes and analyzed for particle size. Figure 6 shows the average PSD percentile (P50, pm) of the 5.0% Morwet™ samples after heating to 80 °C. Figure 6 shows that the average particle sizes did not increase significantly compared to what is shown in Figure 5. Dissolution at that temperature does not appear to occur within the time frame shown. Example 3: Methods for the CMC of dispersing micronized sulfur at various concentrations of Morwet™ in demineralized and tap water The micronized sulfur dispersions that were tested and monitored were the following: QQO / nn / Lznz / E / Yi Surfactant concentration (% by weight of Moewet™) in dispersant solution Water Type 1% demineralized 1.5% demineralized 2% demineralized 3% demineralized 5% demineralized 1% tap 1.5% tap 2% tap 3% tap 5% tap Fresh micronized sulfur dispersions were produced at 100 Hz using demineralized or tap water at sulfur concentrations of approximately 60%. Samples were produced with various surfactant concentrations and were collected and analyzed immediately after production for PSD. PSD was tested hourly or daily until particle size stabilized. Figures 7 and 8 show the 10th to 95th percentile particle size (µm) of the 100 Hz micronized sulfur dispersion produced with Morwet™ at 1% over time (hours) with demineralized water (Figure 7) or tap water (Figure 8). Both Figure 7 and Figure 8 show that within the first 24 hours after production, no significant increase in particle size was observed. For the tap water sample, a slight increase in the 95th percentile was observed, from 7 microns to 8 microns, after 22 hours. However, overall, particle sizes did not increase in either the demineralized or tap water with 1% Morwet™. Figures 9-11 show the 10th to 95th percentile particle size (µm) of the 100 Hz micronized sulfur dispersion produced with 1.25% Morwet™ (Figure 9) over time (hours) in demineralized water and with 1.5% Morwet™ over time (hours) with demineralized water (Figure 10) or tap water (Figure 11). Figure 9 shows the upper 95th percentile of particle size in 1.25% Morwet™, which, after 5 hours of post-production, increased by approximately 6 to 12 microns. The lower particle size percentiles did not change significantly, suggesting that only the larger particles grew. It is proposed that during the homogenization process, elemental sulfur was solubilized and subsequently deposited onto the larger particles. This would also indicate that the CMC for demineralized water is below 1.25% Morwet™. Figure 10 also shows that the 95th percentile, upper particle size in the 1.5% Morwet™ and demineralized water sample after 5 hours of post-production increased in size from 6 to 9 microns, suggesting that the larger particles increase in size, while the smaller particles did not change significantly. Figure 11 shows that the 95th percentile, upper particle size in the tap water sample and Morwet™ at 1.5% after 5 hours of post-production, increased slightly in size from approximately 6.5 to 10.5 microns. The lower particle size percentiles did not change significantly in size, thus suggesting that only the larger particles increased slightly in size. Figures 12 and 13 show the 10th to 95th percentiles of particle size (microns) of the 100 Hz micronized sulfur dispersion produced with Morwet™ at 2% over time (hours) with demineralized water (Figure 12) or tap water (Figure 13). Figure 12 shows that the upper percentiles 80-95 increased, and the 95th percentile increased from approximately 6 to 12 meters after 5 hours of post-production. This shows that the 15 QQO / nn / Lznz / E / Yi larger particles increased in size, but smaller particles remained relatively unchanged. Figure 13 shows that the upper 90th-95th percentiles increased in size, with the 95th percentile increasing from 6 to 17 microns after 20 hours of post-production. No significant change was observed with the smaller particles. Figures 14 and 15 show the 10th to 95th percentiles of particle size (microns) of the 100 Hz micronized sulfur dispersion produced with Morwet™ at 3% over time (hours) with demineralized water (Figure 14) or tap water (Figure 15). Figure 14 shows that the 40th–95th percentiles of particle size (micrometers) increased in size after 5 hours of post-production. The average particle size (50th percentile) increased from approximately 3 to 6 micrometers, while the upper 95th percentile increased from approximately 6 to 38 micrometers. Figure 15 shows that the 40th–95th percentiles for particle size (microns) also increased after 5 hours of post-production. The average particle size (50th percentile) increased from 3 to 7 microns, and the upper 95th percentile increased from 7 to 38 microns. This would indicate that the CMC is below 3% of Morwet™ in tap water. Figures 16 and 17 show the 10th to 95th percentile particle size (µm) of the 100 Hz micronized sulfur dispersion produced with Morwet™ at 5% over time (hours) with demineralized water (Figure 16) or tap water (Figure 17). Figure 16 shows that the 30th to 95th percentiles of particle size (µm) increased significantly after 5 hours of post-production, and the 95th percentile increased almost immediately after production. The average particle size (50th percentile) increased from approximately 2.5 to 8 µm, while the 95th percentile increased from 6 to 33 µm. Figure 17 shows that the 10th–95th percentiles of particle sizes (µm) increased significantly after 5 hours of post-production, with the 90th and 95th percentiles increasing immediately after production. The lower 10th percentile increased from approximately 0.7 microns to 2 µm, the average (50th percentile) increased from approximately 2.6 µm to 12 µm, and the upper 95th percentile increased from approximately 5 microns to 37 µm. The observed changes in particle size suggest that for demineralized water samples containing less than 1.25% Morwet™, particle sizes did not change significantly. Between 1.25% and 3% Morwet™, only the 16th percentile showed any change. QQO / nn / Lznz / E / Yi The particle size changed. Above 3% Morwet™, most particle size percentiles increased significantly. For tap water, a slight increase in particle size was observed in the upper particle size percentiles between 1.5% and 3% Morwet™, but no significant changes were observed for the average or lower particle size percentiles. At 3% Morwet™ and above, significant changes in particle size were observed for all particle size percentiles. This would suggest that the CMC for demineralized water is between 1% and 1.25% Morwet™, and for tap water it is between 2% and 3% Morwet™. At these concentrations of Morwet™, a significant dissolution of sulfur occurs during the homogenization process and causes significant particle growth upon cooling. Example 4: Methods for PSD of micronized sulfur dispersion over time with Morwet™ at 1.5% or 5.0% in agitated or settled state The micronized sulfur dispersions that were tested and monitored were prepared as follows: 1. 1.5% Morwet™ + demineralized water 2.5% Morwet™ + demineralized water A dispersion of micronized liquid sulfur at 100 Hz with approximately 65% ​​sulfur was produced and sampled in flasks. One sample was kept in suspension by continuous stirring with a stirring rod, and the other sample was allowed to settle. The dissolved solids concentration (DSC) of both samples was measured daily for 7 days, and subsequently weekly for 4 weeks. On day 4, 100 g of the stirred and settled samples were transferred to a new flask, and Morwet™ powder was added to a final concentration of 5%. The 5% Morwet™ samples were maintained under the same conditions as the previous samples and measured daily for one week and weekly for one month. All measurements are averages of three replicates, with standard error bars. Figure 18 shows the PSD P50 of the samples in which the Morwet™ concentration was not modified. It appears that agitation of the sample delayed particle growth. Between day 0 and day 1, the agitated sample increased in size from 0.5 to 3 microns, while the settled sample increased immediately after production to 3.5 microns (day 0). This suggests that agitation after production delays the deposition of dissolved sulfur onto existing particles, thus slowing particle growth. οοο / ηη / ίζηζ / Β / γι Figure 19 shows the average PSD percentile (P50, pm) for those samples in which additional Morwet™ was added (on day 4) to the treatments to achieve a total concentration of 5.0%. With the addition of additional surfactant, no significant change in particle size was observed. Example 5: Methods for the CMC of dispersing micronized sulfur at various concentrations of Triton C-405tM in tap water The micronized sulfur dispersions that were tested and monitored were the following: QQO / nn / Lznz / E / Yii Surfactant concentration (% by weight of Moewet™) in dispersing solution Water Type 1% tap 1.5% tap 2% tap 5% tap Fresh micronized sulfur dispersions were produced at 100 Hz using tap water at sulfur concentrations of approximately 60%. Samples were produced with various surfactant concentrations and were collected and analyzed immediately after production for PSD. PSD was tested hourly or daily until the particle size stabilized. Figures 20 to 24 show the 10th to 95th percentiles of particle size (microns) of the 100 Hz micronized sulfur dispersion produced with Triton X-405™ at 1%, 1.5%, 2% and 5% over time (hours) with tap water. Figure 20 shows that the 80th–95th percentiles for particle size increased, with the 95th percentile increasing from 6 to 30 microns after 24 hours of post-production and the 80th percentile increasing from 5 to 13 microns. No significant change was observed with the smaller particle sizes. This suggests that the CMC is below 1% for Triton X405™ in tap water. Figure 21 shows that the 70th to 95th percentiles of particle size (µm) increased in size. The particle size at the 70th percentile increased from 3 to 9 µm, and the upper 95th percentile increased from 6 to 40 µm. Figure 22 shows that the 50th-95th percentiles increased in size, the 95th percentile increased from 5 to 40 thousandths and the average (50th percentile) increased from 3 to 11 thousandths. Figure 23 shows that the particle size percentiles from the 10th to the 95th increased in size. The particle size at the 10th percentile increased from less than 1 micrometer to 7 micrometers, and the particle size at the upper 95th percentile increased from 7 to 60 micrometers. The observed changes in particle size suggest that for tap water samples containing less than 1.5% Triton X405™, particle sizes did not change significantly below the 80th percentile. Between 1% and 2% Triton X405™, only the upper particle size percentiles increased in size. Above 2% Triton X405™, most particle size percentiles increased significantly in size. This suggests that the CMC for tap water is below 1% Triton X405™. As expected, the CMC for Triton X405™ in demineralized water should be lower than in tap water. Interpretation References in the descriptive report to "modality," "a modality," etc., indicate that the described modality may include a particular aspect, element, structure, or characteristic, but not all modalities necessarily include that aspect, element, structure, or characteristic. Furthermore, such phrases may, but do not necessarily, refer to the same modality referenced elsewhere in the description. Moreover, when a particular element, structure, or characteristic is described in relation to a modality, it is within the knowledge of a person skilled in the art to affect or connect that module, aspect, element, structure, or characteristic with other modalities, whether or not explicitly described.In other words, any module, element, or feature can be combined with any other element or feature in different ways, unless there is an obvious or inherent incompatibility between the two, or it is specifically excluded. It is further noted that claims may be drafted to exclude any optional elements. As such, this statement is intended to serve as a basis for the use of exclusive terminology, such as "only," "solely," and the like, in connection with the citation of claimed elements or the use of a negative limitation. The terms "preferably," "prefer," "prefer," "optionally," "may," and similar terms are used to indicate that a referenced article, condition, or stage is an optional (not mandatory) feature of the invention. The singular forms *un*, *una*, and *el / la* include the plural reference unless the context clearly indicates otherwise. The term *and / or* means any of the articles, any combination of the articles, or all of the articles with which this term is associated. The phrase *one or more* is readily understood by someone skilled in the art, particularly when read in the context of its use. The term "approximately" may refer to a variation of ±5%, ±10%, ±20%, or ±25% of the specified value. For example, approximately 50% in some modalities may result in a variation between 45% and 55%. For whole number ranges, the term "approximately" may include one or two whole numbers greater than and / or less than a quoted whole number at each end of the range. Unless otherwise stated in this description, the term "approximately" is intended to include values ​​and ranges close to the quoted range that are equivalent in terms of the composition's functionality or modality. As a person skilled in the art will understand, for any purpose, particularly in terms of providing a written description, all intervals cited herein also encompass any and all possible subintervals and combinations thereof, as well as the individual values ​​comprising the interval, particularly whole numbers. The cited interval includes every specific value, whole number, decimal, or identity within the interval. Any enumerated interval can be readily recognized as sufficiently described and allows the same interval to be divided into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each interval discussed herein can be readily broken down into a lower third, middle third, upper third, and so on. As anyone skilled in the art will understand, all language such as between, at least, greater than, less than, more than, or above, and the like, includes the number in question, and these terms refer to intervals that can be further broken down into subintervals as discussed earlier. Similarly, all the relationships mentioned in this description also include all the subrelationships contained within the larger relationship.

Claims

1. A method for producing micronized sulfur, comprising the steps of: (a) preparing an emulsion of liquid sulfur in an aqueous dispersing solution comprising a surfactant at a concentration below 1.5% (by weight) and below its critical micelle concentration (CMC); and (b) solidifying the liquid sulfur droplets to produce a micronized sulfur suspension.

2. The method of claim 1, wherein the amount of surfactant is optimized by measuring the CMC in the solution and determining an optimum surfactant concentration that minimizes particle size and / or particle size variation.

3. The method of claim 1 or 2, wherein the surfactant concentration is less than approximately 75%, 50%, 40%, 30% or 20% of its CMC.

4. The method of any one of claims 1 to 3, wherein the surfactant comprises an anionic surfactant or a non-ionic surfactant.

5. The method of claim 4, wherein the surfactant comprises naphthalene sulfonate or octylphenol ethoxylate.

6. The method of any one of claims 1 to 5, wherein the surfactant concentration is less than approximately 0.75% (by weight).

7. The method of any one of claims 1 to 6, wherein the dispersing solution is prepared with demineralized water.

8. The method of any one of claims 1-7, comprising the additional step of periodically stirring the suspension of micronized solid sulfur.

9. A micronized sulfur product having a medium or average particle size of approximately 5 microns or less, or preferably approximately 3 microns or less.

10. The micronized sulfur product of claim 9, wherein 95% of the particles are less than 12, 10, 9 or 8 microns.

11. A micronized sulfur product, dispersed in a solution comprising an aqueous dispersant comprising a surfactant at a concentration below 1.5% (weight) and below its critical micelle concentration (CMC).

12. The product of claim 11, wherein the mean or median particle size is less than approximately 5 microns in size, or less than approximately 3 microns in size, and wherein the mean or median particle size does not substantially increase during 24 hours, 2, 3, 4, 5, 6, 7 or 30 days.

13. The product of claim 11 or 12, wherein the mean or median particle size of the particles smaller than the 50th, 60th, 70th, 80th, 90th or 95th percentile does not substantially increase over time.

14. The product of any one of claims 11 to 13, further comprising a fertilizer salt, such as urea ammonium nitrate (UAN), ammonium sulfate, ammonium polyphosphate (APP).

15. The product of any one of claims 11 to 14, further comprising a herbicide, pesticide or fungicide.

16. The product of any one of claims 11-15 further comprising a suspending agent, such as a polysaccharide, such as a substituted or unsubstituted starch, pectate, alginate, carrageenan, gum arabic, guar gum and xanthan gum, or a clay.

17. The product of any one of claims 11 to 16, wherein the solution does not comprise solubilized sulfur.