Process for the preparation of sulfur suspension by atomization of molten sulfur

Abstract

The invention relates to the preparation of sulfur suspension, in which molten sulfur is atomized and the resulting atomized sulfur droplets are incorporated in a dispersion medium. In the process the formation of atomized sulfur droplets is separated in space and time from their incorporation. The invention also relates to the sulfur suspension produced, as well as the atomizing-suspending device used for the preparation of sulfur suspension and the rotary disc used in the atomizing-suspending device.

Description

[0001] PROCESS FOR THE PREPARATION OF SULFUR SUSPENSION BY ATOMIZATION OF MOLTEN SULFUR

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a process for the preparation of sulfur suspension wherein molten sulfur is atomized, and the resulting atomized sulfur droplets are incorporated in a dispersion medium, in the process, the formation of atomized sulfur droplets is separated in space and time from their incorporation. The invention also relates to the sulfur suspension produced, as well as the atomizing-suspending device used for the preparation of sulfur suspension and the rotary disc used in the atomizing-suspending device.

[0004] BACKGROUND OF THE INVENTION

[0005] Sulfur is widely applied in the agriculture for example as pesticides, crop yield enhancers or fertilizers and it is also used in the rubber industry and other industry sectors. Sulfur- containing formulations are available in various forms, such as suspension concentrates (SC), suspension emulsions (SE), wettable powders (WP), water dispersible granules (WG) and oil dispersions (OD). In SC formulations produced for agricultural purposes the average particle size is 0.5-2.0 pm while in WP and WG formulations the particle size, or the primer particle size of sulfur is 2-10 pm, however considering the coverage of sprayed vegetation the latter sizes are less advantageous. SC and SE formulations are usually produced from powdered sulfur. Effective dispersing and wetting additives are used in these.

[0006] The preparation of sulfur containing suspensions from solid sulfur is complicated and expensive. In the frequently used process, lumpy sulfur is dry-ground in an inert gas atmosphere in a powder plant designed for this purpose. The use of an inert gas atmosphere and the antistatic protection of the equipment are both necessary because the elemental sulfur is highly susceptible to electrostatic charge and is also flammable.

[0007] Sulfur dispersions can also be produced by using chemical methods. In such processes, for example, hydrogen sulfide and sulfur dioxide are reacted in an aqueous protective colloidal solution. These procedures are also highly expensive.

[0008] Due to the above disadvantages, attempts have been made to produce sulfur suspensions from molten sulfur. In such processes, the molten sulfur is directly introduced into a dispersantcontaining medium and incorporated in it. Depending on the crystal structure the melting point of sulfur is above 115-120°C, so the process is carried out at high temperatures, and the sulfur suspension is formed during cooling. Since this method not only has to be carried out at high temperatures, but the cooling also takes a lot of time, the product is exposed to heat for a long period, thus no heat-sensitive components can be used, but for these suspensions the dispersants can only be selected from a relatively narrow range, such as for example the lignin sulfonates, which are more resistant to thermal effects.

[0009] The sulfur content of suspensions mentioned in the literature is usually 55-60%. Thinner suspensions are prone to sedimentation, and in case of higher sulfur content, the pourability and handling of the material is inappropriate due to the high viscosity.

[0010] In sulfur products, the size of sulfur particles varies greatly, ranging from colloidal properties to coarser particles. An additional problem is that the formulations with larger particle sizes are prone to sedimentation and adhesion, furthermore it is not easy to redisper the adhered product. Adhesion can be reduced by using suitable protective colloids and dispersants. However, a large particle size is detrimental to the quality, physical and chemical properties of the product, and also reduces the effectiveness of the product.

[0011] In US Patent No. US2348736, molten sulfur was emulsified at autogenous pressure at a temperature below 160°C in a monobutylphenylphenol sodium monosulfonate and resin containing aqueous solution of the same volume with a pH of 7-8.5. Then it was introduced into a homogenizer under pressure at an elevated temperature. When poured, the evaporation of water cooled the mixture, as a result of which the sulfur solidified, and it was then treated with sulfite waste liquor.

[0012] In US patent No. US3461080, molten sulfur was homogenized in an aqueous solution containing lignosulfonate to produce an emulsion at temperatures above 113°C and below lignosulfonate polymerization.

[0013] Therefore, only heat-resistant dispersants can be used for these processes.

[0014] In US Patent No. US4372872, the addition of elemental sulfur to suspension fertilizers was described. The mechanical background, including the mixer, was built on the equipments of fertilizer mixing plants, and the technical parameters and quality requirements were also selected from this area, which differ from the usual requirements in plant protection and other industries, which the inventors are striving for with this solution.

[0015] Accordingly, in the above-mentioned US patent No. US4372872, sulfur was added to an aqueous medium mixed by a high-shear mixer, optionally in a molten state, where the aqueous medium contained a clay thickener and a surfactant. 20-60 wt% of the sulfur particles produced remained on a sieve with mesh size of a 20 (approximately 840 pm). The shelf-life has only been tested for 7 days (see US4372872, examples 3 and 5), as the suspension fertilizers are used quickly. However, after all this time, sedimentation could have already started, because they wrote that the product "can be easily re-dispersed with gentle stirring".

[0016] In US publication document No. US2017 / 0210675 Al, urea-sulfur fertilizer was produced by mixing components in a static mixer or dispersing mill, optionally in the presence of ionic surfactant. In addition, optionally sulfur or urea or both were added in a molten state. As a product, they obtained large granules of 1.5-5.0 mm. Further disadvantage of this method is that biuret or thiourea contamination may form in the procedure.

[0017] According to the invention, a high-purity sulfur suspension starting from molten sulfur is produced, where the formation of atomized sulfur droplets is separated in space and time from their incorporation in a dispersion medium. The dispersion medium is not exposed to high thermal loads, so it is possible to use heat-sensitive dispersants that are more effective than commonly used non-heat-sensitive agents, such as lignin sulfonates or clays. Additionally, the excipients can be selected from the range of heat-sensitive dispersants in a much more diverse way than from the dispersants used in state-of-the-art solutions.

[0018] According to the present invention, equipment operating on any principle can be used for the atomization of sulfur, provided that the process of the invention can be carried out under the above-mentioned conditions, i.e., for example, which can be heated to temperatures higher than the melting point of sulfur and in which the molten sulfur droplets can be incorporated in a flowing dispersion medium with a temperature not reaching 60°C.

[0019] The main types of suitable atomizers are the following (see Jozsef Turba: „Porlaszt6k”, or Wikipedia Online Encyclopedia):

[0020] Hydraulic atomizers that operate at a pressure of 6 to 20 bars. It includes all the atomizers that obtain the energy required for the decomposition of the liquid jet from the pressure or from the kinetic energy obtained from the pressure. Of these, two characteristic basic types are distinguished, the rotation chamber atomizers (rotary atomizers) and the collision pressure atomizers.

[0021] Rotation chamber type atomizer: The turbulent liquid flow is held together by the wall of the vessel to the nozzle, where the cohesiveness ceases, so does the original direction of travel, and the liquid is broken up into jet beams of different directions depending on the previous flow conditions and the physical properties of the liquid. The important feature of atomization is the cone of atomization.

[0022] Collision hydraulic pressure type: When the collision occurs outside the atomizer, then two fluid jets meet each other in such a way that they are not completely opposite to each other, so due to the appropriate internal design of the atomizer they can also collide in the interior space. Mechanical atomizers: Their rotating or vibrating elements create a velocity difference between the liquid and the air, causing the fluid jet to decompose. These include rotary disc or so-called rotary atomizers, their other types are revolving plate, rotary cup (rotary cup, rotary hopper), rotary cylinder, rotary pivot (rotary pin), rotary brush, electromechanical (vibration) atomizers.

[0023] Pneumatic atomizers: In these devices, the liquid jet is broken down into tiny droplets by some kind of compressible fluid (gas or steam stream). Since two flowing media are present, this atomization is known as dual-medium atomization. Compared to the others, these atomizers have high energy requirements, which are suitable for fine atomization.

[0024] Electrostatic atomizers: One type includes those where the flight and / or the impact of droplets are controlled by electrostatic forces, while the other type includes such atomizers where droplet dispersion occurs under the influence of electrostatic forces.

[0025] Ultrasonic atomizers: The decomposition and atomization of liquids are performed by ultrasound.

[0026] In terms of the energy consumption of atomization, among the above equipment the rotary disc or the so-called rotary atomizers are preferable. Hereinafter the term of rotary disc is used. The simplest version of rotary discs is a lamelliform atomizer, the cup-shaped design is a bit more complex. The present invention refers to a more complex atomizing device and rotary disc, on which smaller molten sulfur droplets are formed during atomization than in the conventional atomizers. Furthermore, the particles produced in atomizers known in the literature are either atomized directly into a liquid, or the receiving medium is a solid surface. In the present technical solution, the resulting sulfur droplets flying through the space of the atomizer, become part of a continuously moving dispersion medium.

[0027] SUMMARY OF THE INVENTION

[0028] The invention concerns the preparation of sulfur suspension, in which molten sulfur is atomized, whereby atomized sulfur droplets are formed, which are incorporated in a dispersion medium. In the process, the formation of atomized sulfur droplets is separated in space and time from their incorporation, whereby the atomized sulfur droplets hit the liquid layer of a continuously flowing dispersion medium and freeze, then they are incorporated in the dispersion medium, the resulting sulfur suspension is continuously drained, stirred, and then recirculated to the atomization chamber, where it incorporates additional sulfur, and the sulfur content of the sulfur suspension circulated in this way increases continuously.

[0029] According to an embodiment of the invention, molten sulfur heated to 120-160°C, preferably 140-150°C, is fed into the atomizer in a nitrogen or argon atmosphere. Atomization is carried out at atmospheric pressure in the presence of air.

[0030] According to an embodiment of the invention, an aqueous medium or an organic medium is used as a dispersion medium and one or more, optionally heat-sensitive dispersants are used as dispersants, the thickness of the flowing liquid layer of the dispersion medium is up to 7 mm, preferably 1-5 mm, temperature of it is not more than 45°C, preferably 30-35°C. Organic media can be, for example, propylene glycol, rapeseed oil, soybean oil, wood oils, mineral oils, transesterified oil varieties (biodiesels), avocado oil, castor oil, cottonseed oil, sesame oil, mustard seed oil, peanut oil, olive oil, palm oil, coconut oil, oils containing trans fatty acids as well as their mixtures.

[0031] According to an embodiment of the invention, a batch process is performed, which is started with a measured amount of dispersion medium and sulfur, and continued until the molten sulfur is used up, thus a sulfur suspension of a predetermined concentration is obtained.

[0032] According to certain embodiments of the invention, the resulting sulfur suspension is optionally ground using conventional wet grinding processes.

[0033] The invention relates to pilot-scale atomizing-suspending equipment suitable for producing sulfur suspension, which has a molten sulfur tank 2, an atomizing tank 15, a suspension tank 30 and optionally other elements shown in Figure 1.

[0034] The invention also relates to atomizing tank 15, which contains atomizing head 14, as well as a slightly conical atomization chamber 16, the diameter of which decreases downward, and liquid distribution system 22 that includes liquid inlets 24 located in a circle on the top of the wall of atomizing tank 15.

[0035] An embodiment of the pilot-scale atomizing-suspending device of the invention is shown in Figure 2.

[0036] An embodiment of atomizing tank 15 according to the invention is also shown in Figure 2. In this embodiment, atomizing tank 15 contains a bottom-driven rotary disc as atomizing head 14, above which sulfur inlet nozzle 39 and under this, heating elements 18 are located. The other elements of atomizing tank 15 are described in Figure 1.

[0037] The invention also relates to rotary disc 17, one of its embodiments is shown in Figure 4. In this embodiment, rotary disc 17 has outer cone surface 41 and dropping edge 43.

[0038] Another embodiment of rotary disc 17 is shown in Figure 5. In this embodiment, rotary disc 17 has outer cone surface 41 and dropping edge 43, furthermore outer cone surface 41 has circumferential groove 42. In the equipment shown in Figure 2, both Figure 4 and Figure 5 type rotary disc 17 may be used. The invention also relates to a sulfur suspension, which contains spherical sulfur particles in aqueous dispersion, where the average diameter of the sulfur particles is in the range of 70 pm to 130 pm and at least 90% of the diameter of sulfur particles is below 200 pm.

[0039] In an embodiment according to the invention the sulfur suspension has a sulfur content of 57.6 wt% and its viscosity is in a range of 300-1500 mPas.

[0040] The invention also relates to a sulfur suspension in organic medium or a partly organic and partly aqueous medium, which contains spherical sulfur particles, where the diameter of the sulfur particles is in the range of 70 pm to 130 pm and at least 90% of the diameter of sulfur particles is below 200 pm.

[0041] In certain embodiments according to the invention, where the sulfur suspension prepared in organic medium, the organic medium is for example, propylene glycol, rapeseed oil, soybean oil, wood oils, mineral oils, transesterified oil varieties (biodiesels), avocado oil, castor oil, cottonseed oil, sesame oil, mustard seed oil, peanut oil, olive oil, palm oil, coconut oil, oils containing trans fatty acids as well as their mixtures.

[0042] The sulfur suspensions according to the invention contain one or more, optionally heatsensitive dispersants, and optionally, additives selected from a group of viscosity adjusters, rheological modifiers, trixotrophics, sediment relievers. Furthermore, they can contain other additives commonly used in the respective uses selected for example from antifreeze, antifoaming, preservatives, salt additives and any combination thereof. Special excipients used in the sulfur suspensions in organic media are for example the antioxidants and vulcanizing agents.

[0043] In certain embodiments according to the invention, after grinding the sulfur suspension by conventional wet grinding processes, the diameter of the sulfur particles is in the range of 0.5 pm to 5 pm.

[0044] DESCRIPTION OF THE FIGURES

[0045] Figure 1 shows the schematic drawing of a pilot-scale atomizing-suspending device;

[0046] Figure 2 shows the schematic drawing of a pilot-scale atomizing-suspending device having a bottom-driven rotary disc;

[0047] Figure 3 shows a drawing of a conventional rotary disc;

[0048] Figure 4 shows a schematic drawing of the rotary disc according to one of the embodiments according to the invention;

[0049] Figure 5 shows a schematic drawing of the rotary disc according to another embodiment according to the invention; Figure 6 shows a macro photo shot at high rotation speed on a section of the rim of a rotary disc as shown in Figure 4;

[0050] Figure 7 shows microscopic images of sulfur suspension, in a Projectina type transmission comparative microscope (on the left) and an incident light top-illuminated microscope (on the right);

[0051] Figure 8 shows the characteristic size distribution curve / data of the atomized sulfur particles in the suspension according to the invention;

[0052] Figure 9 shows the size distribution curve of the sulfur particles produced by the pregrinding and subsequent fine-grinding of the suspension according to the invention.

[0053] Figure 10 is the plant flow chart which includes the process of industrial scale production of sulfur suspension.

[0054] DETAILED DESCRIPTION OF THE INVENTION

[0055] The technical solution according to the invention relates to the preparation of sulfur suspension containing sulfur particles, as well as the atomizing-suspending device used for the preparation and the liquid distribution system containing atomizing tank used in it. The invention also covers a uniquely designed rotary disc that can be used in the atomizing tank. Furthermore, the invention covers aqueous and organic sulfur suspension produced by the process of the present invention.

[0056] In the process according to the invention, sulfur droplets are produced from molten sulfur by using atomization, the formation of sulfur droplets is separated in space and time from their incorporation in the dispersion medium. The dispersion medium flows forming a thin layer. In the process of atomization, the molten sulfur droplets form a spherical shape and fly through the airspace of the atomizing tank and hit the layer of the flowing dispersion medium, where they retain their spherical shape and freeze, then they are incorporated in the dispersion medium. Meanwhile, the dispersion medium does not warm up significantly, so heat-sensitive dispersants can also be used in the dispersion medium.

[0057] In the process of the preparation of sulfur suspension according to the invention, an atomizing-suspending device consisting of three main units are preferably used, where the mentioned units are as follows: sulfur melting unit, atomizing unit and suspending unit.

[0058] The atomizing unit can be a heated atomizing unit operating on practically any principle, where the droplet formation and the incorporation of droplets in the dispersion medium are separated in space and time in the atomizing unit. Examples of atomizers that are known on their own and can be used in the technical solution according to the invention, are shown above in the section entitled “Background of the invention”.

[0059] The atomizing unit of the atomizing-suspending device according to the invention contains the flow-through atomizing tank equipped with a liquid distribution system. The liquid distribution system converts the dispersion medium into a liquid film that flows continuously in the space of the atomizer. From the sulfur melting unit, molten sulfur is led to the atomizing head, from which sulfur droplets detach, and fly through the space of the atomizer, then they are incorporated in the flowing dispersion medium. The sulfur-containing dispersion medium is then fed into the suspending unit, where it is stirred in a tank, and then the sulfur-containing dispersion is recirculated into the atomizing tank through a disaggregator, pump and pipeline, where the liquid again reaches the atomization chamber through the liquid distribution system and takes up further sulfur. In this cyclic process, such a sulfur suspension is obtained, the sulfur content of which gradually increases.

[0060] One of the embodiments of the atomizing-suspending device according to the invention is shown in Figure 1. Its molten sulfur tank 2 is equipped with mixing rod 5 driven by mixing motor 3. In molten sulfur tank 2, the atmosphere above the molten sulfur is filled with a inert gas, preferably nitrogen or argon gas, which is introduced through inert gas inlet 4. The structural material of molten sulfur tank 2 is made of acid-resistant steel, for example. Molten sulfur tank 2 is heated with oil, which is fed in counter-current, introduced at fuel oil inlet 6, and let out at fuel oil outlet 7. From molten sulfur tank 2, the molten sulfur is transferred through heated drain ball tap 10 and heated sulfur transport tube 11, which pipeline is equipped with heating jacket 12, by using heated pump 13, e.g. a gear pump, to atomizing head 14 in atomization chamber 16 of atomizing tank 15. The elements connecting molten sulfur tank 2 and atomizing tank 15, namely heated drain ball tap 10, heated sulfur transport tube 11 , pipeline heating jacket 12 and heated pump 13 are also heated by the fuel oil passing through fuel oil inlet 6 and fuel oil outlet 7. Melted sulfur droplets are detached from atomizing head 14 during atomization. Sulfur is led into atomizing head 14 in liquid state with a viscosity of 4 to 9 mPas. Any atomizing head used in atomizing equipment known in the literature can be used as atomizing head, examples of which are presented above in the section “Background of the Invention" . For example, the rotary atomizing head can be used with either top or bottom-drive.

[0061] Atomizing tank 15 has a cooling jacket in which cooling water circulates through cooling water inlet 20 and cooling water outlet 21. Furthermore, atomizing tank 15 has rim 40 and is equipped with perforated air distribution plate 23.

[0062] Atomizing tank 15 according to the invention has liquid distribution system 22 with liquid inlets 24. Through these, the dispersion medium is introduced through liquid inlets 24 to atomization chamber 16, where it flows down the wall of atomizing tank 15 and is transformed into an essentially coherent liquid film. The sulfur-containing dispersion medium flows through suspension outlet 25 at the bottom of atomization chamber 16 into suspension tank 30, through connecting element 26, which connects atomization chamber 16 and suspension tank 30, to prevent the escape of sulfur mist. This phenomenon will be detailed below, in the description of suction hole 38. Suspension tank 30 is equipped with anchor stirrer 32, which is driven by stirring motor 31. From suspension tank 30, the mixed sulfur-containing dispersion medium is fed back through drain opening 44, screw pump 28, disaggregator 27 and suspension transport tube 29 to liquid inlets 24 located on rim 40 of atomizing tank 15. Atomization chamber 16 and suspension tank 30 is cooled in counter-current, where the cooling water enters cooling jacket 37 of suspension tank 30 at cooling water inlet 33 and leaves at cooling water outlet 34, and then enters cooling jacket 37 of atomizing tank 15 at cooling water inlet 20 and exits from there through cooling water outlet 21.

[0063] A part of the atomized sulfur does not enter the liquid but remains in the airspace of atomizing tank 15 and forms sulfur mist, which could be a source of occupational health hazard if released into the environment. To prevent this, the mist generated in the atomizing tank is exhausted with the air above the suspension tank through suction hole 38, thus orienting the mist in the direction of the liquid, so that its droplets can still enter the liquid.

[0064] One of the embodiments of the atomizing-suspending device shown in Figure 1 is represented by the atomizing-suspending device shown in Figure 2. It contains an atomizing tank that has bottom-driven rotary disc 17 as atomizing head. Above rotary disc 17 sulfur inlet nozzle 39 and below rotary disc 17 heating elements 18 are located.

[0065] Atomization chamber 16 of atomizing tank 15 shown in Figure 2 is asymmetrically designed. The reason for this is that the suspension and the exhaust air leave in the same place and through a large cross-section, which can be achieved with an asymmetrical position due to the central position of the rotary disc.

[0066] The process for the preparation of sulfur suspension according to the invention may start with any liquid sulfur having a viscosity of up to 10 mPas. Accordingly, in one of the embodiments of the process according to the invention, molten sulfur is introduced into molten sulfur tank 2. In another embodiment, solid sulfur is measured into, then melted in the said tank.

[0067] The temperature of molten sulfur transferred from molten sulfur tank 2 to the atomizing tank 15 is 120-160°C, preferably 140-150°C, and its flow rate is 30-500 1 / h, preferably 80-160 1 / h. In Figure 2 a schematic drawing of a preferred atomizing tank is shown, wherein rotary disc 17 according to the invention is used, one of the embodiments of which is shown in Figure 4. This rotary disc 17 has outer cone surface 41 and dropping edge 43 with an increasing diameter in the direction of suspension outlet 25. In the process of atomization, the molten sulfur moistens outer cone surface 41, forming a melt film on it. The thickness of the molten sulfur film is primarily determined by the shape of the disc, the rotation speed and the feeding speed. From the melt film on outer cone surface 41, the atomized sulfur droplets are torn out, the size and shape of which are determined by the angles of the disc. The released droplets fly in the atomization plane defined by rotary disc 17, towards the dispersion medium flowing on the wall of atomization chamber 16. The mentioned outer cone surface 41 forms an obtuse angle with the atomization plane, so that the droplets are not tom off the surface perpendicularly. This causes smaller droplets than in the case of a conventional rotary disc. The spherical shape and the size of droplets are determined at the moment of separation from outer cone surface 41, and these characteristics are also retained in the dispersion medium.

[0068] The main function of the dropper 43 edge is to limit the rotor wind.

[0069] The rotary disc shown in Figure 5 differs from the one shown in Figure 4 mainly in that it contains circumferential groove 42 on the outer cone surface 41. The conical surface continues below circumferential groove 42, thus providing a larger heating surface on the outer cone surface 41. In addition, a larger heating element can be placed underneath, so the cooling effect of rotation can be more stably compensated.

[0070] Figure 6 shows rotary disc 17 according to Figure 4 in operation. Figure 6 is a macro photo taken of a section of rotary disc 17 at high rotational speed. This process allows you to take a sharp photo of a small moving surface with a short exposure time. In this case, although a sufficiently small surface had to be photographed to detect flying droplets, but also a sufficiently large surface to make the surface of the rotary disc and a large number of droplets visible. Furthermore, to avoid contamination, the camera had to be placed outside the equipment, so a telephoto lens and a close-up lens were used. In this way, the inventors were able to photograph the 48x36 mm field of view from a distance of 28-30 cm, and due to the rapid movement of the droplets and the rotary disc, the inventors had to use a flash with a short flash time. The motion of the flying droplets was 1.4 mm and the flash time was about 1 / 25000 sec, which is about 4000 rpm, and the exposure time is the same as the flash time.

[0071] Figure 6 clearly shows that the melt film moistens the outer cone surface, which can be recognized by the black lines painted on it. The black lines are painted at 1 cm intervals, these lines are used to estimate the dimensions. Figure 6 shows that during operation the outer cone surface of the rotary disc is moistened with molten sulfur, and it can be seen that the rotation causes the detachment of molten sulfur droplets from the outer cone surface.

[0072] As it was mentioned before, in the procedure, the macroscopically detected temperature of the suspension hardly rises during the procedure, i.e. it remains below 60°C all the time, despite the fact that sulfur droplets with a temperature of 120-160°C, preferably 140-150°C, reaches the dispersion medium or the sulfur suspension. Accordingly, when the sulfur droplets cool down suddenly, they do not significantly increase the temperature of their microenvironment, thus the heat-sensitive substances present there will not be damaged. This is evidenced by the fact that the colloidal properties of the suspension do not deteriorate with the use of heat-sensitive dispersants. Accordingly, despite the incorporation of high- temperature sulfur droplets, the temperature of the circulated suspension usually does not exceed 40-50°C, and typically remains around 30-35°C. Nevertheless, suspension tank 30 is cooled, primarily because a lot of heat is released during the above-mentioned grinding operations, which optionally follow the sulfur suspension preparation process, and thus it is advisable to start the grinding of the material cold.

[0073] As discussed above, the dispersion medium is fed back through inlets of the liquid distribution system 22 to the wall of atomizing tank 15. Although the liquid film still shows unevenness in the upper part of the wall, as the diameter of atomizing tank 15 decreases downwards, the thickness of liquid film and also its velocity increases, and as a result, the unevenness decreases and the film forms a more uniform layer around the wall of atomizing tank 15. In the atomization plane, the liquid film is almost continuous and uniform, its thickness is 1-5 mm. The thickness of the liquid film also increases due to the increasing viscosity with the concentration of sulfur suspension, so it can reach 7 mm at the end of the process.

[0074] Molten sulfur droplets produced during the atomization fly out of the disc and the surface tension forces them to take on a spherical shape. The surface of the liquid film is pierced by the sulfur droplets hitting the film, and when getting into the film they immediately freeze. Despite the high impact velocity, they remain spherical, as can be clearly seen in Figure 7, which is described in more detail in Example 1.

[0075] The sulfur droplets remain in molten state until the moment of impact into the dispersion medium, which have been established from the fact that where a smaller liquid defect occurs on the wall of the atomizing tank, in the atomization plane - during abnormal operation - a larger solid piece of sulfur appears adhering to the wall. This is due to the fact that the sulfur droplets solidify when stacked on top of each other and slowly "grow quasi-stalactites". This clearly shows that the sulfur droplets remain in a molten state capable of moistening until the moment of impact.

[0076] The sulfur-containing dispersion medium circulates between atomizing tank 15 and suspension tank 30 at a speed of 2000-9000 1 / h, typically 5000-6000 1 / h.

[0077] In the process, the dispersion medium gradually converts into a sulfur suspension of higher and higher concentrations, while its viscosity increases. However, by the appropriate design of the pipes, namely by avoiding horizontal pipes, by using optimally large diameter and preferably short pipes, as well as by using a suitable pump, and mixing at the right speed, the transport of the suspension can be kept at a constant flow rate. Such a suitable pump is screw pump 28, also known as the monopump, which contains a screw-shaped rotor and a slightly flexible stator whose role is to implement liquid displacement. The significance of this in the present technical solution is that it can deliver the same flow rate regardless of viscosity and concentration, i.e. screw pump 28 is designed to provide a constant flow rate depending on the speed, even at several bars pressure.

[0078] The role of disaggregator 27 is primarily to disperse any particles that may be generated before entering the pump, and also to perform some sort of minimal shredding. Additionally, disaggregator 27 exerts a suction effect on the material in the tank with its rotating motion, thus facilitating the pump's transport work.

[0079] In the pilot-scale industrial equipment according to the invention, exact quantities are measured, so when the amount of sulfur is consumed at the end of the operation, the desired sulfur concentration is obtained. Thus, there is no need to adjust the sulfur content afterwards. Using the process according to the invention, a concentrated sulfur suspension of 57-58 wt%, for example 57.6 wt%, is typically produced, however by measuring the appropriate quantity and quality of components, up to 70 wt% sulfur suspension can be produced.

[0080] In addition, the aqueous-based sulfur suspension according to the invention typically contains 10-12 wt% additives. These are for example as follows: dispersants, viscosity adjusters, rheological modifiers, thixotropies, sedimentation loosener, antifoaming, antifreeze, preservatives, salt additives and other additives depending on the area of use, such as preservatives and vulcanizing agents.

[0081] The average particle size and particle size range of the sulfur suspension produced in the atomizing-suspending equipment according to the invention can be planned in advance. In the equipment corresponding to the schematic drawing shown on Figure 2, by using the rotary disc shown in Figure 5, for example a suspension containing sulfur particles with an average diameter in the size range from about 70 pm to 130 pm is produced, where at least 90% of the diameter of the sulfur particles is less than 200 pm. The typical particle size distribution of this is shown in Figure 8 (see Example 1). However, by changing the atomization conditions, for example particles with a diameter of 40 pm to 70 pm can be produced as well.

[0082] In the process according to the invention, no larger sulfur particles are produced than planned, so there is no need for subsequent filtration.

[0083] The particles of sulfur suspension according to the invention are reconstructible in size, and they are dense, compact and spherical, as a result of which although the viscosity increases at high concentrations, the product still remains treatable, e.g. pourable.

[0084] At 57.6% sulfur content, the viscosity of the suspension is usually between 300 and 1500 mPas. Furthermore, due to the spherical shape, the particles are less prone to stick together than the typically irregularly shaped particles produced in a traditional process.

[0085] The sulfur suspension preparation process according to the invention can also be carried out on a factory scale. The flowchart of this is shown in Figure 10. In this process, molten sulfur is introduced into a heated melt tank 51. From there, it is passed into the atomizing tank through a pipeline equipped with a heating jacket, as well as a filter to remove minor mechanical contaminants. The weight of the introduced sulfur is determined by a flow-through speedometer (Coriolis) and measuring system. This transmitter is located directly in front of the atomizing head. Obviously, in this embodiment, several parallelly operating atomizing tanks 52 are used, in each of which the circulation was carried out by using separated pumps 53. The atomizing tanks 52 have a volume of 100-120 1 each, approximately 110-1 coolable tanks. These are placed above the suspension tank 55 and work into them. The volume of the suspension tank 55 is about 4-7 m3. The function and principle of operation of the atomizing tanks 52, suspension tank 55 and disaggregator 54 are the same as those described in Figures 1 and 2.

[0086] In this embodiment the rotary disc shown in Figure 5 is preferably used.

[0087] As mentioned above, in the technical solution according to the invention, it is possible to start from solid sulfur or molten sulfur. High-purity molten sulfur is produced in large quantities as a by-product in the oil industry during desulfurisation using the Claus process or the Super Claus process. This is obtained from the manufacturer in molten form and transferred from the transport truck in this state into the molten sulfur tank of the equipment according to the invention or into the melt tank of the plant equipment. On the one hand, this sulfur is much cheaper, and on the other hand, the above-mentioned disadvantages of working with solid sulfur can be avoided, and a very high-quality, high-purity sulfur suspension is obtained.

[0088] In one of the embodiments of our invention, the inventors start from the above-mentioned high-purity molten sulfur, the basic physical properties of which are presented in Table 1.

[0089] Table 1 Properties of sulfur raw material

[0090] Based on the above, sulfur can be characterized as follows: poor thermal conductivity, good electrical insulation and high resistance, highly prone to electrostatic charge, flammable, also ignitable by friction, prone to spontaneous combustion above about 180°C, and small specific heat and phase transition heat. https: / / material-properties.org / sulfur-thermal-properties-melting-point-thermal- conductivity-expansion / (link available on 07.09.2024 https: / / www.nuclear-power.com / sulfur-specific-heat-latent-heat-vaporization-fusion / (link available on 06,25,2024);

[0091] Sofekun, G. O., Evoy, E., Lesage, K. L., Chou, N., & Marriott, R. A. (2018). The rheology of liquid elemental sulfur across the k-transition. Journal of Rheology, 62(2), 469- 476.

[0092] Steunenberg, R. K., Trapp, C., Yonco, R. M., & Cairns, E. J. (1972). Electrical Conductivity of Liquid Sulfur and Sulfur-Phosphorus Mixtures.

[0093] Sofekun, G. O., Evoy, E., Lesage, K. L., Chou, N., & Marriott, R. A. (2018). The rheology of liquid elemental sulfur across the k-transition. Journal of Rheology, 62(2), 469- 476.

[0094] Nickless, G. (1968). Inorganic sulphur chemistry.

[0095] Naray-Szabo, I., Organic chemistry L, General section, Non-metallic elements and their compounds, publisher: Akademiai Kiado (1956).

[0096] In the technical solution according to the invention, both heat-sensitive and heat-resistant dispersants can be used. Heat-resistant dispersants are most often lignin sulfonate derivatives. Chemically different types of dispersants are ethoxylates, which have very diverse properties, however, most of them cannot withstand high temperatures, but due to their varied capabilities, they provide much more freedom and higher quality in the formulation of recipes.

[0097] Among the dispersants that meet the colloidal criteria, there are also heat-sensitive dispersants, such as ethoxylated non-ionic surfactants (these are often liquid), and among anionic tenzides there are also well-suited ethoxylated types. This is because the degree of ethoxylation or propoxylation can be used to control the hydrophilic-lipophilic balance, i.e. the HLB number.

[0098] Examples of temperature-sensitive dispersants that can be used in the methods according to the invention includes:

[0099] Sodium polycarboxilate (Geropon T / 36, manufacturer: Azelis);

[0100] 4,4-dihidroxy diphenyl sulfonate condenzate sodium salt (Supragil GN, manufacturer: Azelis);

[0101] Anionic polymer (Atlox LP-1, manufacturer: Croda)

[0102] Acryl aryl polioxyethylene ether phosphate salt (Emulson AG / TRST / HA);

[0103] Condensed methyl naphthalene sulfonate sodium salt (Madeol MW, Envipol MW, Supragil MNS90)

[0104] Tri styrylphenyl ethoxylates (Lamberti Emulson group: Emulson 7717-A; Emulson 7720- A; Emulson 7725 -A);

[0105] Tri styrylphenyl alkoxylates (Emulson TRS-204);

[0106] EO-PO block copolimers (Lamberti Envipol group: Envipol 104; Envipol 105);

[0107] Acryl polymers (Envipol 3010; Envipol 7754; Envipol TRN);

[0108] Polymer surfactants (Envipol 871; Envipol PNM);

[0109] Synthetic polymer surfactant complex (Envipol BRN);

[0110] Eto-propoxy dated surfactants (Envipol LPE; Envipol PE);

[0111] Tri styrylphenyl ethoxylates (Envipol TRSA; Envipol TRSK; Envipol TRSS; Envipol TRST-HA);

[0112] Nonionic tristyrylphenol surfactants (Solvay Soprophor group: Soprophor BSU / C-R);

[0113] Tri styrylphenyl ethoxylates (Soprophor BSU / C; Soprophor TS / 54; Soprophor TSP / 724; Soprophor S / 40; Soprophor CY / 8; Soprophor S / 25; Soprophor BSU; Soprophor 796 / P; Soprophor 3D33 ); Phosphate esters (SoprophorFLK; Soprophor FL / 60; SoprophorFL; SoprophorFLK / 70; Soprophor SC3; Soprophor FL-R).

[0114] In addition to or in combination with the above, heat-resistant dispersants can be used as well. These include the following: Ultrazine NA; Greensperse® S9; Vanisperse® CB; Greensperse® CA-N.

[0115] Examples of additives that can be used in sulfur suspensions according to the invention include: thixotropic agent, e.g. attapulgit (Attagel 50, manufacturer: BASF), sediment relivier, such as silica powder or xanthan gum (Keltrol AP, manufacturer: Azelis), antifoaming, such as silicone oil emulsion (Antschiuma GEN, manufacturer: Lamberti), viscosity adjuster, e.g. stearic acid or palmitic acid, emulsifier, such as ethoxylated castor oil (Emulsion CO9, manufacturer: Lamberti), antioxidant, vulcanizing agent (TMTD), antifreeze, such as propylene glycol, which also serves as a medium for sulfur suspension in organic media.

[0116] The sulfur suspension according to the invention is optionally ground to a smaller particle size. The sulfur suspension preparation process according to the invention can be well integrated into standard industrial wet sulfur suspension grinding processes. The sulfur particles with a diameter of 70 pm to 130 pm produced by the process according to the invention still tend to settle, so immediately before grinding, the material is stored in a buffer tank (this is not shown in the figures), where stirring is carried out to inhibit sedimentation. First, pre-grinding with a corundum disc is performed, so that the average particle size is reduced to the range between 30 pm and 70 pm, and then, after fine grinding in a colloidal mill or bead mill, the size of most of the grains is essentially between 0.5 pm and 2 pm, with a tail section extending up to 5 pm (see example 1, Figure 9).

[0117] This distribution can be influenced by changing the operating conditions, such as the length of time spent in the bead mill or the diameter of the beads. Under the microscope, these particles are naturally no longer spherical, but have the apperarance of debris or crushed material. Despite this, the viscosity of sulfur suspension does not increase after fine grinding. These small particles hardly settle, so the suspensions remain properly pourable and can be stored for up to 3 years.

[0118] In the above, the process and equipment according to the invention for the preparation of sulfur suspensions in an aqueous medium have been described. However, the process and equipment according to the invention are equally suitable for the preparation of partially or completely organic dispersion. The preparation of these is the same as described for aqueous sulfur suspensions, and differs from them only in composition.

[0119] Accordingly, the invention also covers sulfur dispersions in organic media.

[0120] In organic dispersions, the organic medium is for example, propylene glycol, rapeseed oil, soybean oil, wood oils, mineral oils, transesterified oil varieties (biodiesels), avocado oil, castor oil, cottonseed oil, sesame oil, mustard seed oil, peanut oil, olive oil, palm oil, coconut oil, oils containing trans fatty acids as well as their mixtures. Their sulfur content can for example contain 20-60% and 10-12% of various excipients.

[0121] Furthermore, by using the process according to the invention, partly aqueous and partly organic sulfur suspensions can be produced. In these suspensions, the proportion of organic medium in aqueous dispersion is usually at least 25 wt% and not more than 55 wt%. In the process, the organic medium is emulsified in the aqueous dispersion, after which the atomization and suspension of sulfur is carried out.

[0122] The aqueous and organic sulfur suspensions according to the invention can be used for a variety of purposes, examples of which are listed below.

[0123] Main areas of use of aqueous sulfur suspension:

[0124] 1) Wastewater treatment: Solid sulfur with a grain size of 0-140 pm is used to clean sewage sludge from nitrates. Multicomponent mixtures are used for wastewater treatment, so their formulation is possible in the form of a concentrated suspension. (Guo, G., Li, Z., Chen, L., Ling, Q., Zan, E, Isawi, H., ... & Lu, H. (2022). Advances in elemental sulfur-driven bioprocesses for wastewater treatment: From metabolic study to application. Water Research, 213, 118143.)

[0125] 2) Cosmetics industry: Sulfur suspensions are used as an anti-dandruff agent. Patent No. WO2021173203 Al describes a cosmetic product containing sulfur suspension in which the particle size of sulfur is in the range of 0-150 pm, and the sulfur content of the suspension is 0.1-10%.

[0126] 3) Medicine: Sulfur suspensions are used as an additive to toiletries, for the treatment of acne vulgaris, acne rosacea, seborrheic dermatitis. (Hagers Handbuch der Pharmazeutischen Praxis (in German). Vol. 6B (4th ed.). Berlin-Heidelberg-New York: Springer. 1978. pp. 672-9. ISBN 3-540-07738-3. )

[0127] 4) Rubber industry: In the rubber industry, elemental sulfur is used as a vulcanizing agent. US4902775A patent describes vulcanizing preparations containing elemental sulfur. In one of the embodiments, the vulcanizing agent contains a sulfur / olefin adduct with a free elemental sulfur content of about 39-46 wt%, this is a premix.

[0128] Main areas of use of elemental sulfur suspensions in organic media:

[0129] Preparation of sulfur-containing composites: Colloidal particles of elemental sulfur or its derivatives have also been used to produce nanocomposites. Elemental sulfur powder dispersed in an organic solvent was used as a core, on which synthesized polythiophene (PTh) was coated in situ. The method also has allowed to control the sulfur content of composites, so composites with a sulfur content of more than 80 wt% were obtained. The area of its use is the cathode of lithium batteries.

[0130] Source: https: / / pubs.acs. org / doi / epdf / 10. 1021 jpl 114724

[0131] Rubber industry: An organic sulfur suspension may be an advantageous vulcanizing agent. It can be advantageous especially in cases where it is intended to be added to and dispersed in rubber with high viscosity that is difficult to mix. In such case, before adding it to the rubber it is preferable to disperse the sulfur already present in an organic medium instead of powder form. An example of this is the STRUKTOL SU 105 vulcanizing paste, in which sulfur is dispersed in a mixture of organic and inorganic dispersants.

[0132] Source : https: / / struktol.de / de / produkte / kautschuk / schwefelpraeparationen /

[0133] EXAMPLES

[0134] The following examples serve to better understand the technical solution according to the invention by presenting some specific embodiments. However, the technical solution according to the invention is not limited to the compositions given here.

[0135] 1 , Example

[0136] Preparation of concentrated aqueous sulfur suspension from molten sulfur Starting materials:

[0137] Sulfur suspension of Example 1 is prepared in the equipment corresponding to the schematic drawing of Figure 2 using the type of rotary disc shown in Figure 4. At the beginning of the procedure, molten sulfur is measured into molten sulfur tank 2.

[0138] The operating parameters of the system are as follows: molten sulfur temperature 140- 150°C, volume flow 120 1 / h, rotary disc diameter 168 mm, speed 3400 rpm, suspension circulation speed 6000 1 / h, temperature not exceeding 30°C.

[0139] At the beginning of the procedure, the room-temperature aqueous dispersion medium is measured into suspension tank 30, along with the required amount of additives specified in the table above, except for the rheological modifier, of which only a part is measured. Because in the presence of the full amount of the rheological component, the viscosity would be too high towards the end of the process, which would cause a technological problem in the circulation of the suspension. On the other hand, provided the suspended sulfur is ground to a smaller size after the sulfur suspending process according to the invention, the macromolecules of the rheological component degrade in the process. Therefore, the remaining part of the rheological component is added at the ready-mixing process to adjust the viscosity of the suspension. The composition of the product obtained at the end of the process is essentially the same as the measured starting materials.

[0140] The composition of the resulting sulfur suspension is essentially the same as the ratio of the starting materials used in the process. The sulfur content of the product is 57.6 wt%, and its viscosity is 300-1500 mPas, depending on the setting of the above-mentioned parameters.

[0141] Figure 7 shows microscopic images of the sulfur suspension prepared in 2% aqueous dilution as described in Example 1. The image was taken with a projection Projectina comparative microscope with a lens with lOx magnification in transmission mode, where the total magnification is 125x on the screen and one unit on the left image is 10 pm. The images clearly show the spherical shape of the particles in suspension.

[0142] Figure 8 shows the size distribution of the sulfur particles in the suspension prepared as described in Example 1. For the distribution imaging, the suspension was diluted with deionized water. The study performed by using the DLS (Dynamic Light Scattering) method and found that the average diameter of the sulfur particles is in the range of about 70 pm to 130 pm, at least 90% of the diameters of the particles are below 200 pm, and sulfur particles above 300 pm are not present at all.

[0143] The particle distribution curve was recorded with a Shimadzu SALD-2300 laser diffraction particle size analyzer. The light source in the device is a semiconductor laser that emits a monochromatic beam with a wavelength of 680 nm. This beam of radiation passes through the sample dispersed in the liquid, and then the light scattered by the particles at different angles is detected by a multi-element detector and transforms the electrical signal using a suitable optical model and mathematical process, thus the volumetric particle size distribution is obtained. The sampler is Shimadzu SALD-MS23 type, which is suitable for determining the particle size of wet samples. The homogenity and bubble-free nature of the sample filled into the sample container is ensured by using a stirrer and an ultrasonic unit. A pump transports the sample from the vessel to the flow cell, providing continuous circulation. In this construction, the particle size distribution can be determined in the range of 0.017 pm to 2500 pm. The system determines the particle size based on the Mie scattering theory, for which the refractive index of the dispersion medium and the dispersed particle must be given as well. The device operating software, WingS ALD II, includes a feature that automatically calculates the correct refractive index based on the LDR (Light Intensity Distribution Reproduction) method.

[0144] For comparison, figure 9 shows the size distribution of a sample obtained by coarse and then fine grinding of a sulfur suspension, which is visibly in a lower range (about 0.2 pm to 5 pm). This measurement was also performed as described at Figure 8.

[0145] 2, Example

[0146] Preparation of concentrated aqueous sulfur suspension from solid sulfur

[0147] The example 1 is followed, with the exception that solid sulfur is measured into the molten sulfur tank, then it is melted in the molten sulfur tank and its temperature is set to 140- 150°C before starting the procedure.

[0148] 3, Example

[0149] Preparation of organic sulfur dispersion with rapeseed oil

[0150] The procedure is essentially similar to that described in Example 1, with the difference that instead of aqueous dispersion rapeseed oil is measured. The composition of the resulting sulfur dispersion is essentially the same as the ratio of the starting materials used in the process:

[0151] The applied stearic acid or palmitic acid is added to the resulting sulfur suspension at the end of the procedure. Example 4

[0152] Preparation of organic sulfur dispersion with propylene glycol

[0153] The procedure is essentially similar to that described in Example 1, with the difference that instead of aqueous dispersion propylene glycol is measured. The composition of the resulting sulfur dispersion is essentially the same as the ratio of the starting materials used in the process:

[0154] Example 5

[0155] Preparation of organic sulfur dispersion with soybean oil

[0156] The procedure is essentially similar to that described in Example 1, with the difference that instead of aqueous dispersion soybean oil is measured. The composition of the resulting sulfur dispersion is essentially the same as the ratio of the starting materials used in the process:

[0157] The applied stearic acid or palmitic acid is added to the resulting sulfur suspension at the end of the procedure.

[0158] Example 6 Preparation of a partially organic and partially aqueous suspension by atomization of

[0159] Atomizing:

[0160] Mixing to completion:

[0161] In the preparation of sulfur suspension in a partial organic medium, 4 main steps are distinguished. The first step is to create the oily phase (solution 1). The next step is to create the dispersion medium, into which the oily phase is emulsified. Then the molten sulfur is atomized into the dispersion medium similarly to the previous examples, and finally the 3% Keltrol AP aqueous solution is added to the obtained suspension and the whole is mixed intensively.

[0162] In such way, a partly organic and partly aqueous suspension containing 46% by weight of elemental sulfur is formed.

[0163] Among others the advantages of the technical solution according to the invention are as follows: a) a high-quality, high-purity sulfur suspension is obtained; b) spherical sulfur particles are formed, resulting in a relatively low viscosity, so that the sulfur suspension remains pourable even at higher concentrations; c) the required sulfur particle size range can be adjusted by selecting centripetal acceleration; d) the viscosity will not be higher even after the optional fine grinding applied at the end of the standard grinding operations following after the process according to the invention; e) in the pilot-scale plant process according to the invention, the exact sulfur content of the suspension can be adjusted at the start of the process, so the sulfur content does not need to be adjusted with sulfur powder in a separate operation; f) no filtration is necessary at the end of the process, as no large pieces of sulfur are formed; g) no dry grinding is used in the process does, and no suspended sulfur dust is formed during the work with molten sulfur, therefore there is no need for dust control; and h) the atomizing tank operates in a flow-through mode, therefore the difficulties caused by the change in the liquid level known from the literature do not have to be taken into account.

Claims

CLAIMS1. Process for the preparation of sulfur suspension, characterized in that molten sulfur is atomized, during which atomized sulfur droplets are formed, which are incorporated into a dispersion medium, in which process the formation of atomized sulfur droplets is separated in space and time from the incorporation thereof, during which the atomized sulfur droplets hit the liquid layer of a continuously flowing dispersion medium having a temperature of maximum 60°C and freeze, then they are incorporated into the dispersion medium, the resulting sulfur suspension is continuously drained and stirred before recirculated to the atomization chamber, where it incorporates additional sulfur droplets, and the sulfur content of the circulated sulfur suspension continuously increases, while its temperature remains under 60°C throughout the process.

2. The process according to claim 1, characterized in that molten sulfur heated in nitrogen or argon atmosphere to 120-160°C, preferably to 140-150°C, is atomized.

3. The process according to claim 1 or 2, characterized in that an aqueous medium or an organic medium is used as a dispersion medium, and one or more, optionally heat-sensitive dispersants are used as dispersants, the thickness of the flowing liquid layer of the dispersion medium is up to 7 mm, preferably 1-5 mm, its temperature is not more than 45°C, preferably 30-35°C, the organic medium is for example propylene glycol, rapeseed oil, soybean oil, wood oils, mineral oils, transesterified oil varieties (biodiesels), avocado oil, castor oil, cottonseed oil, sesame oil, mustard seed oil, peanut oil, olive oil, palm oil, coconut oil, oils containing trans fatty acids, or mixtures thereof.

4. The process according to any of the previous claims, characterized in that a batch process is performed starting from measured amounts of dispersion medium and sulfur, and the process is carried out until the molten sulfur is used up, to prepare a sulfur suspension with predetermined concentration.

5. Atomizing-suspending device for performing any of the procedures according to claims 1-4, wherein the atomizing-suspending device has a molten sulfur tank (2), to which an atomizing tank (15) equipped with an atomizing head (14) is connected through a heated transport tube (11) for molten sulfur, and a suspension tank (30) is connected to the suspensionoutlet (25) of the atomizing tank (15), characterized in that the atomizing tank (15) has a conical atomization chamber (16) with a decreasing diameter towards the suspension outlet (25) and a liquid distribution system (22), which liquid distribution system (22) contains liquid inlets (24) located around the rim (40) of the wall of atomizing tank (15), and it is equipped with a sulfur inlet nozzle (39) and a heating element (18), and the atomizing head (14) is a rotary disc (17) which has an outer cone surface (41) with an increasing diameter towards the suspension outlet (25) and a dropping edge (43), and the drain opening (44) of the suspension tank (30) and the liquid inlets (24) of the atomizing tank (15) are connected to each other by a suspension transport tube (29).

6. The equipment according to claim 5, characterized in that the outer cone surface (41) of the rotary disc (17) with an increasing diameter towards the suspension outlet (25) is provided with a circumferential groove (42).

7. Rotary disc (17), characterized in that it has a dropping edge (43) and an outer cone surface (41) with an increasing diameter towards the suspension outlet (25).

8. The rotary disc (17) according to claim 7, characterized in that its outer cone surface (41) is provided with a circumferential groove (42).

9. Sulfur suspension containing dense compact spherical sulfur particles in aqueous dispersion, which sulfur particles have an average diameter in the range of 70 pm to 130 pm and at least 90% of the diameters of sulfur particles are below 200 pm, the aqueous dispersion contains one or more dispersants, of which at least one dispersant is heat-sensitive, and the aqueous dispersion optionally contains commonly used additives, which sulfur suspension is prepared by the process according to any of claims 1 to 4.

10. Sulphur suspension according to claim 9, which has a sulfur content of 57.6 wt%, and a viscosity in the range from 300 to 1500 mPas.

11. Sulfur suspension containing dense, compact spherical sulfur particles in organic medium or in a partially organic and partially aqueous medium, which sulfur particles have an average diameter in the range from 70 pm to 130 pm and at least 90% of the diameters of thesulfur particles are below 200 pm, the organic medium contains one or more dispersants, of which at least one dispersant is heat-sensitive, and the organic medium optionally contains commonly used additives, which sulfur suspension is prepared by the process according to any of claims 1 to 4.

12. The sulfur suspension according to claim 11, wherein the organic medium can be propylene glycol, rapeseed oil, soybean oil, wood oils, mineral oils, transesterified oil varieties (biodiesels), avocado oil, castor oil, cottonseed oil, sesame oil, mustard seed oil, hazelnut oil, olive oil, palm oil, coconut oil, oils containing trans fatty acids, and mixtures thereof.

13. Process for the preparation of sulfur suspension containing sulfur particles in a diameter range from 0.5 pm to 5 pm, characterized in that the sulfur suspension according to any of claims 9 to 12 is grinded by using conventional wet grinding processes.

14. A sulfur suspension containing sulfur particles in the diameter range from 0.5 pm to 5 pm, which is prepared by the process according to claim 13, which can be stored for at least three years and during this it remains pourable.