CN87105366A - Granular potassium sulfate and method for producing same - Google Patents
Granular potassium sulfate and method for producing same Download PDFInfo
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- CN87105366A CN87105366A CN87105366.7A CN87105366A CN87105366A CN 87105366 A CN87105366 A CN 87105366A CN 87105366 A CN87105366 A CN 87105366A CN 87105366 A CN87105366 A CN 87105366A
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D1/00—Fertilisers containing potassium
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- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
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Abstract
本发明提供一种粉化百分数很低的硫酸钾造粒法和生产出具有良好流动性的颗粒硫酸钾的方法，以及按上述方法获得的颗粒硫酸钾。本发明方法包括：选自一组氢氧化钙、氧化钙、氢氧化镁、氧化镁、碳酸镁和氨中至少一种组分，以相对于所述未反应硫酸量的0.5～2倍当量的量，加到由氯化钾与硫酸在无水状态中反应得到的已转化硫酸钾及所含的未反应硫酸中，继之进行湿法粒化。The present invention provides a method for granulating potassium sulfate with a very low pulverization percentage and producing granular potassium sulfate with good fluidity, and the granular potassium sulfate obtained by the method. The method of the present invention comprises: at least one component selected from a group of calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia, with 0.5 to 2 times the equivalent of the amount of unreacted sulfuric acid The amount is added to the converted potassium sulfate and the unreacted sulfuric acid contained in the reaction of potassium chloride and sulfuric acid in anhydrous state, followed by wet granulation.
Description
The present invention relates to granular potassium sulfate and a method for granulating potassium sulfate. More particularly, it relates to the addition of a neutralizing agent such as calcium hydroxide to the converted potassium sulfate containing unreacted sulfuric acid in an amount followed by wet granulation to provide granular potassium sulfate and a method for producing granular potassium sulfate.
In recent years, fertilizer granulation has been widely used in order to improve the fertilizing operation and to adapt to mechanical fertilization. In particular, mechanical fertilization has been widely carried out in recent years, and, in the case of potassium sulfate, a spherical product having good fluidity has been urgently required. In addition, exceptionally popular bulk blend fertilizers and single granule fertilizers have recently been used. Furthermore, various fertilizers have now been granulated according to methods suitable for their respective physical properties and for their commercial supply. Granular products are also required for potassium sulfate, which is one of the potassium fertilizers, for example. However, referring to the potassium sulfate granulation method, there are various problems in terms of production and quality as described below. For example, in the case of wet granulation in which 5% by weight or more of water is mixed with potassium sulfate as a raw material, it is difficult to obtain a granular product having a desired particle size and a good fertilizer efficiency because potassium sulfate is poor in granulation properties. Thus, when the granular potassium sulfate obtained by pressure granulating a mixture of potassium sulfate and water by a roller press or the like is used as a raw material for bulk blended fertilizers, the granular potassium sulfate in the bulk blended fertilizers is partially pulverized during handling and transportation of the fertilizers. As a result, there is a problem that the bulk blended fertilizer is classified to cause deviation in the respective particle sizes of the fertilizer components.
In addition, granular potassium sulfate of 6 to 12 meshes has been generally used as a raw material for a mixed compound fertilizer or a bulk blended fertilizer, and in the case of using it, since granular potassium sulfate obtained according to the above-mentioned pressure granulation method is subjected to steps of compression, grinding and sieving, etc., many protrusions (projections) are formed on the surface thereof, and the compressive strength is also high. However, the loss is easily generated from the ground surface. In addition, the friable surface of individual particles can also be pulverized when the granular product is handled and transported, characterized by flow. Potassium sulfate obtained by pressure granulation with a roller press according to a conventional method has been used as a raw material for blended fertilizers. However, the percentage of dusting of this product is about 10%, much higher than other granular fertilizers with an average percentage of dusting of 2-3%. Thus, the granular potassium sulfate is first sieved before bulk blending. It is therefore desirable to obtain a granular product of potassium sulfate that does not require re-screening.
The present inventors have conducted extensive studies in order to obtain the above-mentioned desired potassium sulfate granular product. As a result, we have found that the above problems can be solved by adding a neutralizing agent such as calcium hydroxide to the converted potassium sulfate containing unreacted sulfuric acid in an amount followed by wet granulation.
From the foregoing it will be apparent that it is an object of the present invention to provide a process for granulating potassium sulfate with a very low percentage of dusting, resulting in a granular product having good flowability, and to provide granular potassium sulfate obtained by the above process.
The following includes two aspects of the invention, namely: main components (1) and (2), and components (3) to (17) as examples of the present invention:
(1) a granular potassium sulfate is obtained by adding at least one component selected from the group consisting of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
(2) A method for granulating potassium sulfate, comprising adding at least one component selected from the group consisting of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
(3) A granular potassium sulfate is obtained by adding at least one powdery neutralizing agent selected from the group consisting of powdery calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide and magnesium carbonate to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid, followed by press-molding the resultant mixture, grinding the resulting molded product, and wet-granulating the resultant powder.
(4) A process for producing granular potassium sulfate, which comprises adding at least one powdery neutralizing agent selected from the group consisting of powdery calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide and magnesium carbonate in an amount of 0.5 to 2 times equivalent to the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by press-molding the resultant mixture. The molded product thus obtained is ground, and the resulting powder is subjected to wet granulation to wet granulate it.
(5) The process according to (4), wherein the compression molding is carried out by means of a roller press, a briquetting machine, an extruder or a tablet press.
(6) The process according to (4), wherein the wet granulation is carried out with a pan granulator, a drum granulator or an extruder.
(7) The process according to (4), wherein in the wet granulation, water, an aqueous solution of potassium sulfate or an aqueous slurry of potassium sulfate is added to obtain a water content for granulation (water content in the undried wet granulated particles) of 2 to 20% by weight based on the weight of the particles.
(8) The process according to (4), wherein the small granules obtained by the wet granulation are dried and classified, the resulting granules having an excessively large particle size are ground and returned to the apparatus for the wet granulation, and the granules having an insufficient particle size are returned to the apparatus without grinding or after grinding, to obtain granular potassium sulfate.
(9) A granular potassium sulfate obtained by adding at least one neutralizing agent selected from the group consisting of calcium hydroxide, calcium oxide and calcium carbonate to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and unreacted sulfuric acid contained therein in an amount equivalent to 0.5 to 2 times that of the unreacted sulfuric acid to perform wet neutralization, followed by drying the neutralized material, grinding the dried material, and subjecting the ground material to wet granulation.
(10) A process for producing granular potassium sulfate, which comprises adding at least one neutralizing agent selected from the group consisting of calcium hydroxide, calcium oxide and calcium carbonate to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and unreacted sulfuric acid contained therein in an amount equivalent to 0.5 to 2 times that of the unreacted sulfuric acid, while adding water to conduct wet neutralization, followed by drying the converted material, grinding the dried material, and wet-granulating the ground material.
(11) The method according to (10), wherein the amount of water added is 2 to 20% by weight based on the weight of the converted potassium sulfate.
(12) The method according to (10), wherein the wet-neutralized, dried and ground material is mixed with the wet-neutralized material in a ratio of 2: 1, and the mixture is ground.
(13) Granular potassium sulfate is obtained by adding 0.5 to 1.2 times equivalent of ammonia to converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and unreacted sulfuric acid contained therein, followed by wet granulation.
(14) A method for granulating potassium sulfate, which comprises adding 0.5 to 1.2 times equivalent of ammonia to the unreacted sulfuric acid, to converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
(15) The process according to (14), wherein water or aqueous ammonia is added as the water for granulation in the wet granulation.
(16) The method according to (14), wherein the wet granulation is carried out by a tray dryer, a drum dryer or an extruder
(17) The method according to (14), wherein the material obtained by the wet granulation is dried and then sieved to obtain granular potassium sulfate. Wherein oversize material is milled and undersize material is either milled or unground and returned to the wet granulator.
FIGS. 1 to 3 each show a flow chart of an apparatus used in the method of the present invention.
As the potassium sulfate, preferably, potassium sulfate powder used in the present invention is used, and it is preferable to use converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state. However, it is of course possible to use potassium sulfate obtained according to other methods.
The raw material potassium sulfate is not particularly limited in its degree of powderiness, i.e., particle size, and may be used in the present invention if it is a raw material that can be generally used as a tableting raw material or can sufficiently achieve wet neutralization.
In other words, a powder passing through 20 mesh is optimal in terms of its form (the term "mesh" herein refers to the Taylor standard sieve number; this concept applies to the mesh mentioned later), but coarse particles, such as particles of about 5 mesh, are not desirable. If coarse particles of about 5 mesh are used, the wet neutralization is incomplete, thereby reducing the efficiency of the present invention. In other words, there is a tendency that the resultant wet-neutralized product becomes poor in the granulation property, the yield of the resultant granulated product is low, and the hardness (pressure at the time of crushing) of the granulated product is also low.
The neutralizing agent used in the present invention may be any neutralizing agent that reacts with unreacted sulfuric acid contained in the converted potassium sulfate at a temperature of 0 to 200 ℃ and produces a product (sulfate) that does not adversely affect the potassium sulfate as a fertilizer component. The preferable example of such a neutralizing agent is at least one powdery compound selected from the group consisting of calcium compounds and magnesium compounds, such as calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia.
The amount of the powdery compound is 0.5 to 2 times equivalent, preferably 0.8 to 1.5 times equivalent, based on the content of the unreacted sulfuric acid in the converted potassium sulfate.
If the above amount is less than 0.5 times equivalent, potassium sulfate after neutralization has high acidity (i.e., low pH value), and thus is not suitable for bulk blending of fertilizers. If the amount exceeds twice the equivalent, the fertilizer component (K) in the potassium sulfate is neutralized2O) is easily below a certain concentration.
The amount of ammonia used as a neutralizing agent in the present invention is 0.5 to 1.2 times equivalent, preferably 0.8 to 1.0 time equivalent, to the amount of unreacted sulfuric acid contained in the unneutralized potassium sulfate. If the amount is less than 0.5 times equivalent, potassium sulfate after neutralization has high acidity (i.e., low pH value), and thus is not suitable for bulk blending of fertilizers. If the amount exceeds 1.2 times the equivalent, the amount of unreacted ammonia is large, resulting in volatilization at the time of drying, and therefore, the process is complicated for recovering it. Ammonia is generally used in the form of an aqueous solution or a gas.
In the above (4) as an embodiment of the present invention, water is not used at the time of neutralization. The mixing process of the neutralizing agent with the converted potassium sulfate, and the neutralizing process are not particularly limited. In other words, for example, the converted potassium sulfate particles, when tumbled and mixed in known rotary or agitator mixers, are added in a single full amount or in multiple portions of a powdered neutralizing agent in an amount that allows for uniform mixing of the components within a short period of time (e.g., within 30 minutes). To avoid the neutralizing agent adhering to the mixer walls or to a portion of the converted potassium sulfate, the entire neutralizing agent and a portion of the converted potassium sulfate may be pre-mixed, whereby the diluted neutralizing agent may be used in the mixing process.
Further, with respect to neutralization, since the water content contained in the converted potassium sulfate and the neutralizing agent is usually very small amount [ e.g., 0.1% by weight ], no neutralization occurs at the same time of mixing. However, the neutralization may be carried out in a series of steps which follow the present invention, such as press molding, grinding and wet granulation, in other words, the neutralization is substantially completed at the same time as the granulation is completed with the passage of time.
The compression molding method is carried out by means of a compression molding machine such as a roller press, a briquetting machine, an extruder, a tablet press or the like. The conditions of the compression molding method are not particularly limited, but it is preferable to select conditions that allow the compression material to be sufficiently compression molded.
Meanwhile, the press-molded products thus obtained have the following different shapes depending on the kind of the press-molding machine used: tablet shapes, chips, bars, chips, and the like. Either type of compression molded product was ground with a grinder to obtain the particle size as described below. The kind of the grinding machine to be used and the conditions of the grinding are not particularly limited as long as the particle size can be attained as much as possible. For example, a ball mill, a roll mill, or the like can be used. The milling is carried out continuously at room temperature to 50 ℃ or batchwise at room temperature to 50 ℃ for 5 minutes to 5 hours, preferably 10 minutes to 3 hours.
After grinding, the degree of powdering, i.e., the particle size, of the press-molded product is not particularly limited. Generally, a fine particle level as in the raw material for wet granulation is preferred. For example, the product is ground to a particle size of about 100 mesh or less.
The thus-obtained neutralized powdery material was subjected to wet granulation by a granulator. In the above example (4) of the present invention, since the raw materials have been subjected to the steps of mixing, pressure granulation and pulverization, the direct wet granulation step can be effectively carried out.
Although the amount of water used for the wet-process neutralization of example (10) or (15) is not particularly limited, an amount of water sufficient to cause neutralization to such an extent may be sufficient. This amount is generally 2 to 20% by weight, preferably 4 to 15% by weight, based on the weight of the wet product of converted potassium sulphate (this reference also applies to the calculation of the amount of water to be used later). If the amount is less than 2% by weight, neutralization may not be sufficiently performed, so that the efficiency of the present invention is lowered. If the amount of water exceeds 20% by weight, the energy for drying is increased. The result is uneconomical.
The method of mixing the converted potassium sulfate, the neutralizing agent and water is not particularly limited. For example, the above three raw materials to be mixed may be fed into an open mixer or a closed mixer simultaneously or sequentially, and mixed at 0 to 100 ℃, preferably 20 to 80 ℃, for 1 minute to 1 hour, preferably 5 to 30 minutes. However, as long as the efficiency of the present invention is not impaired, only the converted potassium sulfate and the neutralizing agent may be previously mixed, followed by feeding the resultant mixture to the wet granulator together with water to promote the neutralization. The weight ratio of the amount of water added to the neutralized potassium sulfate entering the wet granulator may be in the range of 0.5, or less than 0.5. By using this method, it is possible to partially omit the drying step of the neutralized material from the two drying steps in the entire process of obtaining the product from the raw material.
The above mixer is not particularly limited as long as it can mix raw materials such as powder in a short time. Such as trough blenders, ribbon mixers, and the like, may be used.
Wet granulation is generally carried out using a roll granulator such as a pan granulator, a drum granulator, or the like, or an extruder, but the granulator is not limited thereto.
The amount of water added to the potassium sulfate fed in the wet granulation is not particularly limited, and the water content in the granular product immediately after granulation (i.e., the water content in the small granules; the same applies to the subsequent case) varies depending on the kind of the granulator and the size of the potassium sulfate granules to be added, but is usually 2 to 20% by weight, preferably 4 to 15% by weight, based on the weight of the wet product (the same applies to the subsequent case).
As the water for granulation, water, an aqueous potassium sulfate solution or a potassium sulfate slurry may be used. The granulation water may contain other compounds as long as there is no damage to the granulation effect of potassium sulfate.
The potassium sulfate granulated by the wet granulator is dried by means of a dryer, the kind of the dryer and the drying method are not particularly specified, but it is preferable to select mild conditions in order to reduce the pulverization effect during the drying.
The same dryer can be used for drying both the wet neutralized product and the wet granulated product as long as the efficiency of the invention is not compromised. The granulation conditions above must be selected so that the wet granulated product is sufficiently neutralized before drying. Since the process according to the invention, in many cases, it is often not possible to carry out the neutralization to the required and sufficient extent only by means of the initial wet neutralization, but after the wet neutralization, sufficient neutralization can be continued for the first time when the wet-neutralized product is subjected to the wet granulation stage by grinding.
The granular product obtained in the above way is treated by a screening machine and is screened into products with over-large granularity, products with insufficient granularity and products with insufficient granularity according to the particle diameter. The product with the excessive particle size is ground by a grinder and returned to the wet granulator, while the product with the insufficient particle size is returned to the wet granulator without being ground or ground by a grinder. Whether the product with insufficient particle size is ground depends on the balance of all the particle sizes of the potassium sulphate supplied to the wet granulator.
When the same dryer is used for the two-step drying method using one dryer, there is a wet-neutralized and dried product among the above-mentioned products having insufficient particle size. Neutralization of the oversized product is usually sufficient, and it is therefore possible to replace the step of grinding the product, and to feed the resulting ground product to the wet granulator for grinding the wet-neutralized and dried product, and to feed the resulting ground product to the wet granulator.
The above method is explained with reference to fig. 1 to 3.
In FIG. 1 for the above example (4), the converted potassium sulfate and the neutralizing agent fed from the pipe 1 and the pipe 2, respectively, are mixed (a mixer not shown in the figure), stored in the hopper A through the pipe 3, and then fed to the pressure granulator B, where the mixture is press-molded into a tablet, conveyed to the grinder C through the pipe 4, and the tablet is ground and then fed to the wet granulator D through the bucket elevator 5 to be mixed with the returned product (described later).
In D, the granulation water is scattered by pipe 6, converting the potassium sulphate in powder and fine particles into a wet granular product, which is fed to drier E through pipe 7. The granulated product dried in E is sent by means of a bucket elevator 8 to a screening machine F, where the granulated product is screened according to the granule diameter into oversize products, products and undersize products.
The oversized product is conveyed via pipe 9 to grinder G for grinding.
Product is removed from the system via pipe 11, oversized product and undersized product, each from pipes 10 and 12, are returned to D via flow conveyor 13.
In FIG. 2 for the above example (10), the converted potassium sulfate and the neutralizing agent are fed from the pipe 1 and the pipe 2, respectively, and are fed into the mixer A through the pipe 3, where water is scattered through the pipe 16, and the three raw materials are mixed, as a result of which the neutralization reaction occurs. The neutralized mixture is conveyed via pipe 5 to dryer E (using the same dryer described above) together with the wet granulated product conveyed solely by pipe 7. The potassium sulphate dried in E is conveyed by means of a bucket elevator 8 to a screening machine F, where the potassium sulphate granules are screened according to the granule diameter to form products of excessive size, products of insufficient size and products of insufficient size.
The oversize product is conveyed via pipe 9 to mill G for grinding.
The product is taken out of the system through the pipe 11.
The product of insufficient particle size is conveyed by the pipe 15 to the mill H for grinding or, as such, through the pipe 14 without grinding.
Potassium sulfate product different from the above-described product, i.e., product having an excessively large particle size or an insufficient particle size after grinding, and unground product having an insufficient particle size, is returned to the wet granulator D through the flow conveyor 13 and the pipe 13', where water is scattered on the potassium sulfate in an amount of about 50% by weight or less based on the weight of the potassium sulfate through the pipe 6 to perform granulation.
The undried granular potassium sulfate, which has been subjected to wet granulation as described above, is transported by pipe 7 to the above-mentioned drum dryer E, where it is dried together with the neutralized potassium sulfate (note: wet-neutralized product) transported from mixer a.
In fig. 3 for the above example (14), the pre-ground converted potassium sulfate is conveyed via pipe 1 to the wet granulator D, while the returned product is also sent to D via pipe 13'. On the other hand, ammonia is fed from pipe 2 to D. Granulation was carried out in a wet granulator D. The wet granulated product is fed via a pipe 7 to a dryer E and the resulting dried granulated product is conveyed via a bucket elevator 8 to a screening machine F where it is screened according to the particle diameter into oversize product, product and undersize product. The oversize product is conveyed by pipe 9 to grinder G for grinding.
The product is taken out of the system through the pipe 11.
The product having insufficient particle size is conveyed as it is to the wet granulator D through the pipe 14, the flow conveyor 13 and the pipe 13', or conveyed once to the grinder H through the pipe 15 to be ground. The ground product is taken out through pipe 12 and returned to D via flow conveyor 13 and pipe 13'.
The primary effect of the present invention is that the granular product thus obtained has a high hardness and a low degree of pulverization, i.e., as is apparent from examples 1 and 2 and comparative examples 1 to 4 described below, the hardness (pressure at the time of crushing) of the granular product obtained according to the present invention is equal to 4 to 6 kg in the case of a product having a particle size of 6 to 7 mesh (taylor sieve), and the pulverization percentage is 3 to 5% by weight, that is, it is apparent that the product is much superior to the conventional product in terms of hardness and pulverization percentage.
A second effect of the invention is that the resulting granular product has a good shape (spherical) and good flowability and is therefore quite suitable for mechanical fertilization.
The third effect of the present invention is that the powdered product has good granulation property and high product yield in wet granulation. That is, since the yield of the product is high, the amount of the material to be circulated relative to the amount of the product is reduced to make the scale of the equipment smaller.
Further, as for the above-mentioned example (4) of the present invention, a phenomenon clearly observable from examples 1 to 3 and comparative examples 1 to 3 described below is that the amount of water for granulation is not small in wet granulation by carrying out press molding.
Although the mechanism has not been clarified yet, it is sufficient to conclude that the particle density is increased by performing the compression to reduce the surface area (specific surface area) per unit weight of the particles.
The reduction in the amount of water used for granulation, together with the reduction in the scale of the equipment described above, provides energy-saving efficiency.
The present invention is illustrated in more detail by examples and comparative examples.
Example 1
Slaked lime (purity: calcium hydroxide content 95% by weight) was added as a neutralizing agent in a corresponding amount to the converted potassium sulfate containing 2.8% by weight of unreacted sulfuric acid, followed by compression molding of these components to obtain a pressed sheet, the pressed sheet was crushed with a mortar to a particle size of 10 mesh, and the crushed material (500 g) was successively put into a mixing mill having a mortar with a diameter of 20 cm, and the crushed material was ground for 30 minutes to prepare a sample.
The sample was granulated with a pan granulator having a pan diameter of 45 cm, a rotation number of 25 rpm and an included angle of 45 °, while water was scattered thereon with a sprayer, followed by drying the granulated material with an electrically heated drier adjusted to a temperature of 110 ℃ for 4 hours to obtain a granulated product.
The granulation water consumption and the measured physical parameter values were as follows:
content of granulation water: 9.0% by weight.
Hardness of granular product: 4.3 kg.
Percent powdering of the granular product: 4.1% by weight.
(measurement method) (this measurement method is applicable to the following measurement method).
Hardness: measured with a Kiya type durometer. And taking the average value of the measured values of 20 particles with 6-7 meshes.
Percent pulverization: the granular compound fertilizer mixed with the particle size of 6-9 meshes is measured according to the method of Kumiai research institute.
Comparative example 1
The converted potassium sulfate containing 2.8% by weight of unreacted sulfuric acid was ground into particles passing through 10 mesh by using a mortar, followed by further grinding the ground material in the same manner as in example 1, adding the ground material with a corresponding amount of slaked lime powder, and sufficiently shaking the bagged mixture to prepare a sample.
Granulation and drying were carried out in the same manner as in example 1 to obtain a granulated product.
The measured values are as follows:
content of granulation water: 13.6% (by weight)
Hardness of granular product: 0.8 kg
Percent powdering of the granular product: 65.8% by weight.
Example 2
Granulation and drying of the sample were carried out in the same manner as in example 1 except for using the sample obtained by grinding the granulated product obtained in example 1.
The measured values are as follows:
content of granulation water: 8.2% (by weight)
Hardness of granular product: 5.4 kg
Percent powdering of the granular product: 3.3% by weight.
Comparative example 2
Granulation and drying of the sample were carried out in the same manner as in example 1 except for using the sample obtained by grinding the granulated product obtained in comparative example 1.
The measured values are as follows:
content of granulation water: 10.6% (by weight)
Hardness of granular product: 2.8 kg
Percent powdering of the granular product: 8.1% (by weight)
Example 3
Slaked lime was added in a corresponding amount to the converted potassium sulfate containing 2.7% by weight of unreacted sulfuric acid, and the mixture was then pressure granulated and the resulting tablets were ground with an impact mill to prepare a raw material. And continuously granulating by using a disc granulator with the disc diameter of 3.6 meters, the rotation speed of 10 revolutions per minute and the included angle of 50 degrees and provided with a dryer and a screening machine to obtain a small particle product with 5-9 meshes.
The amount of raw material and the amount of returned product supplied to the pelletizer were 3.0 ton/hr and 6.0 ton/hr, respectively.
The amounts in the screening machine were as follows:
and (3) products with overlarge particle size: 0.6 ton/h (ground and returned)
The product is as follows: 3.0 ton/hr
The product with insufficient granularity: 5.4 ton/hr (return without grinding)
The contents of granulation water and the measured values of the physical parameters of the product were as follows:
content of granulation water: 5.4% (by weight)
The product hardness (6-7 meshes): 5.9 kg
Percent pulverization: 4.7% by weight.
Comparative example 3
Continuous granulation was carried out in the same manner as in example 2 except that the converted potassium sulfate containing 2.7% by weight of unreacted sulfuric acid was ground with an impact mill, followed by addition of a corresponding amount of slaked lime as a neutralizing agent to obtain a raw material, and used in this example.
The amount of raw material and the amount of returned product supplied to the granulator were 2.5 t/h and 8.5 t/h, respectively.
In addition, the amounts in the screening machine were as follows:
product with oversized particle size: 0.6 ton/hr (ground and returned)
The product is as follows: 2.5 ton/h
Product with insufficient particle size: 7.9% ton/h (direct return per se)
The contents of granulation water and the measured values of the physical parameters of the product are as follows:
content of granulation water: 5.8% (by weight)
Product hardness: 2.3 kg
Percent powdering of the product: 9.2% (by weight)
Example 4
The converted potassium sulfate containing 2.8% by weight of unreacted sulfuric acid was crushed into particles passing through a 10 mesh (Taylor sieve), and then these particles (500 g) were put into a mixing mill having a mortar with a diameter of 20 cm, ground for 30 minutes, added with a corresponding amount of powdered slaked lime (calcium hydroxide purity: 95% by weight), and the mixture packed in the bag was sufficiently shaken to obtain a sample (referred to as sample A).
The sample was put into a 2-liter-capacity kneader, followed by spraying water thereon with a sprayer while stirring for a total of 10 minutes, and the resulting material was dried with an electrothermal drier adjusted to a temperature of 110 ℃ for 4 hours to obtain a neutralized product.
The amount of water added by scattering was 7% by weight of the sample.
The neutralized product obtained above was ground with a mixer grinder for 15 minutes to obtain a powder (referred to as sample B).
Sample B was put into a pan granulator having a disc diameter of 45 cm, a rotation number of 25 rpm and an included angle of 45 °, followed by spraying water thereon with a sprayer, and then the resulting material was dried for 4 hours with an electrothermal dryer adjusted to 110 ℃. The physical parameters of the resulting granular product were as follows:
hardness of granular product: 2.5 kg
Percent powdering of the granular product: 8.3% (by weight)
Content of granulation water (reference): 10.3% (by weight)
Comparative example 4
Example 4 was repeated except that neutralization was not carried out to obtain a granular product.
The physical parameters of the granular product were as follows:
hardness of granular product: 0.8 kg
Percent powdering of the granular product: 65.8% (by weight)
Content of granulation water (reference): 13.6% (by weight)
Example 5
Example 4 was repeated except that a mixed sample of sample a (150 g) and sample B (350 g) of example 4 was used to obtain a granulated product.
The physical parameters of the granular product were as follows:
hardness of granular product: 2.1 kg
Percent powdering of the granular product: 9.8% (by weight)
Content of granulation water (reference): 11.1% (by weight)
Comparative example 5
Example 4 was repeated except that a mixed sample of sample a (350 g) and sample B (150 g) was used to obtain a granulated product.
The physical parameters of the granular product were as follows:
hardness of granular product: 1.2 kg
Percent powdering of the granular product: 49.3% (by weight)
Content of granulation water (reference): 11.2% (by weight)
Comparative example 6
Comparative example 5 was repeated except that magnesium hydroxide (MgO: 67% by weight) was used as a neutralizing agent to obtain a granulated product.
The physical parameters of the granular product were as follows:
hardness of granular product: 1.0 kg
Percent powdering of the granular product: 13.8% (by weight)
Content of granulation water (reference): 12.3% by weight.
Comparative example 7
Example 4 was repeated except that magnesium hydroxide was used as the neutralizing agent to give a granular product.
The physical parameters of the granular product were as follows:
hardness of granular product: 2.0 kg
Percent powdering of the granular product: 13.1% (by weight)
Content of granulation water (reference): 10.4% by weight.
Example 6
The converted potassium sulfate containing 2.8% by weight of unreacted sulfuric acid was ground into particles passing through a 10-mesh (Taylor sieve) using a mortar, and then the particles (500 g) were put into a mixing grinder having a mortar with a diameter of 20 cm and ground for 30 minutes to prepare a sample.
The resulting granules were granulated in a pan granulator having a disk diameter of 45 cm, a rotation speed of 25 rpm and an included angle of 45 °, while scattering ammonia water on the granules with an ejector, and the resulting small granules were dried for 4 hours with an electrothermal dryer adjusted to 110 ℃ to obtain a granulated product. The free sulfuric acid and ammonia nitrogen content of the granular product was observed and calculated. As a result, the amount of ammonia added corresponded to 0.96 equivalent of the amount of unreacted sulfuric acid.
The physical parameters of the granular product were as follows:
hardness of granular product: 2.1 kg
Percent powdering of the granular product: 6.8% (by weight)
Content of granulation water (reference): 10.1% by weight.
Comparative example 8
The same product of converted potassium sulfate granules as in example 6, and slaked lime (calcium hydroxide purity: 95% by weight) or magnesium hydroxide [ MgO: 67% by weight), each in the respective amounts, followed by granulating the mixture with the same pan granulator as in example 6 while dispersing water thereon with a sprayer.
The granulated product was dried in the same manner as in example 6 and had the following physical parameters:
example 7
Granulation and drying were carried out in the same manner as in comparative example 8, except that the sample obtained by grinding the granulated product prepared in example 6 was used.
The physical parameters of the granular product were as follows:
hardness of granular product: 2.8 kg
Percent powdering of the granular product: 4.4% (by weight)
Content of granulation water (reference): 8.9% by weight.
Comparative example 9
Granulation and drying were carried out in the same manner as in comparative example 8, except that a sample obtained by grinding the granulated product prepared in example 6 was used.
Claims (17)
1. A granular potassium sulfate is obtained by adding at least one component selected from the group consisting of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
2. A method for granulating potassium sulfate, comprising adding at least one component selected from the group consisting of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate and ammonia in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the unreacted sulfuric acid contained therein, followed by wet granulation.
3. A granular potassium sulfate is obtained by adding at least one powdery neutralizing agent selected from the group consisting of powdery calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide and magnesium carbonate in an amount equivalent to 0.5 to 2 times the equivalent of the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by press-molding the resultant mixture, grinding the resulting molded product, and wet-granulating the resultant powder.
4. A process for producing granular potassium sulfate, which comprises adding at least one powdery neutralizing agent selected from the group consisting of powdery calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide and magnesium carbonate in an amount of 0.5 to 2 times equivalent to the unreacted sulfuric acid to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by subjecting the resultant mixture to compression molding, grinding the resulting molded product, and wet-granulating the resulting powder by a wet granulation method.
5. A method according to claim 4, wherein the compression moulding is carried out by means of a roller press, a briquetting press, an extruder or a tablet press.
6. The process according to claim 4, wherein the wet granulation is carried out by means of a pan granulator, a drum granulator or an extruder.
7. The method according to claim 4, wherein in the wet granulation, water, an aqueous solution of potassium sulfate or an aqueous slurry of potassium sulfate is added to obtain a water content for granulation (water content in the undried wet granulated granule) of 2 to 20% by weight based on the weight of the granule.
8. The process according to claim 4, wherein the small granules obtained by said wet granulation are dried and classified, the granules obtained are of an oversized size, are ground and returned to said wet granulation apparatus, and the granules obtained are of an undersized size, and are returned to said apparatus without grinding or after grinding, whereby granular potassium sulfate is obtained.
9. A granular potassium sulfate is obtained by adding at least one neutralizing agent selected from the group consisting of calcium hydroxide, calcium oxide and calcium carbonate to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid in an amount equivalent to 0.5 to 2 times that of the unreacted sulfuric acid to carry out wet neutralization, followed by drying the neutralized material, grinding the dried material, and wet granulating the ground material.
10. A process for producing granular potassium sulfate, which comprises adding at least one neutralizing agent selected from the group consisting of calcium hydroxide, calcium oxide and calcium carbonate to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid in an amount equivalent to 0.5 to 2 times the amount of the unreacted sulfuric acid, while adding water to conduct wet neutralization, followed by drying the neutralized material, grinding the dried material, and subjecting the ground material to wet granulation.
11. The process according to claim 10, wherein the amount of water added is 2 to 20% by weight based on the weight of the converted potassium sulfate.
12. The method of claim 10, wherein the wet neutralized, dried and ground material is mixed with the wet neutralized material in a ratio of 2: 1 and the mixture is milled.
13. A granular potassium sulfate is obtained by adding 0.5 to 1.2 times equivalent of ammonia to a converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
14. A process for granulating potassium sulfate, which comprises adding 0.5 to 1.2 times equivalent of ammonia to the converted potassium sulfate obtained by reacting potassium chloride with sulfuric acid in an anhydrous state and the contained unreacted sulfuric acid, followed by wet granulation.
15. The method according to claim 14, wherein water or aqueous ammonia is added as granulating water in said wet granulation.
16. The process according to claim 14, wherein the wet granulation is carried out by a tray dryer, a drum dryer or an extruder.
17. The method of claim 14 wherein the material resulting from said wet granulation is dried and sieved to produce potassium sulfate granules. Wherein material of an oversized particle size is ground and material of an undersized particle size is returned to the wet granulator with or without grinding.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP179,193/86 | 1986-07-30 | ||
| JP61179193A JPS6335485A (en) | 1986-07-30 | 1986-07-30 | Granular potassium sulfate and manufacture |
| JP61181137A JPS6340720A (en) | 1986-07-31 | 1986-07-31 | Granular potassium sulfate and its production |
| JP181,137/86 | 1986-07-31 | ||
| JP181,549/86 | 1986-08-01 | ||
| JP61181549A JPS6340721A (en) | 1986-08-01 | 1986-08-01 | Granular potassium sulfate having little powdered rate and its granulating method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN87105366A true CN87105366A (en) | 1988-02-10 |
| CN1033157C CN1033157C (en) | 1996-10-30 |
Family
ID=27324693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN87105366A Expired - Fee Related CN1033157C (en) | 1986-07-30 | 1987-07-30 | Granular potassium sulfate and process for producing the same |
Country Status (2)
| Country | Link |
|---|---|
| KR (2) | KR910009598B1 (en) |
| CN (1) | CN1033157C (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007071175A1 (en) * | 2005-12-19 | 2007-06-28 | The Mosaic Company | Granulation of sulfate of potash (sop) |
| CN100542957C (en) * | 2007-10-18 | 2009-09-23 | 南风化工集团股份有限公司 | A kind of prilling process of anhydrous sodium sulphate |
| CN102249766A (en) * | 2010-05-18 | 2011-11-23 | 国投新疆罗布泊钾盐有限责任公司 | Manufacture method of particle potash fertilizer |
| CN102690144A (en) * | 2012-03-28 | 2012-09-26 | 河南力浮科技有限公司 | Method for producing granular potassium sulfate |
| CN102701832A (en) * | 2012-03-28 | 2012-10-03 | 河南力浮科技有限公司 | Production method of granular potassium sulfate slow-release fertilizer |
| CN105294270A (en) * | 2015-11-11 | 2016-02-03 | 河北萌帮水溶肥料有限公司 | Potassium sulfate particle and preparation method thereof |
| CN105339325A (en) * | 2013-06-28 | 2016-02-17 | 钾肥和盐类集团钾肥有限公司 | Process for producing pellets containing potassium chloride, magnesium sulfate hydrate and magnesium oxide |
| CN105339326A (en) * | 2013-06-28 | 2016-02-17 | 钾肥和盐类集团钾肥有限公司 | Process for producing pellets containing potassium chloride and magnesium sulfate hydrate |
| CN112158862A (en) * | 2020-05-15 | 2021-01-01 | 青岛碱业钾肥科技有限公司 | Production method of low-chlorine potassium sulfate |
| CN113387372A (en) * | 2021-07-07 | 2021-09-14 | 东南大学 | Method for roughening surface of potassium sulfate particles |
-
1987
- 1987-07-30 KR KR1019870008336A patent/KR910009598B1/en active
- 1987-07-30 CN CN87105366A patent/CN1033157C/en not_active Expired - Fee Related
- 1987-07-30 KR KR1019870008336A patent/KR880001551A/en not_active IP Right Cessation
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007071175A1 (en) * | 2005-12-19 | 2007-06-28 | The Mosaic Company | Granulation of sulfate of potash (sop) |
| CN100542957C (en) * | 2007-10-18 | 2009-09-23 | 南风化工集团股份有限公司 | A kind of prilling process of anhydrous sodium sulphate |
| CN102249766A (en) * | 2010-05-18 | 2011-11-23 | 国投新疆罗布泊钾盐有限责任公司 | Manufacture method of particle potash fertilizer |
| CN102690144A (en) * | 2012-03-28 | 2012-09-26 | 河南力浮科技有限公司 | Method for producing granular potassium sulfate |
| CN102701832A (en) * | 2012-03-28 | 2012-10-03 | 河南力浮科技有限公司 | Production method of granular potassium sulfate slow-release fertilizer |
| CN102701832B (en) * | 2012-03-28 | 2014-01-22 | 河南力浮科技有限公司 | Production method of granular potassium sulfate slow-release fertilizer |
| CN105339326A (en) * | 2013-06-28 | 2016-02-17 | 钾肥和盐类集团钾肥有限公司 | Process for producing pellets containing potassium chloride and magnesium sulfate hydrate |
| CN105339325A (en) * | 2013-06-28 | 2016-02-17 | 钾肥和盐类集团钾肥有限公司 | Process for producing pellets containing potassium chloride, magnesium sulfate hydrate and magnesium oxide |
| CN105294270A (en) * | 2015-11-11 | 2016-02-03 | 河北萌帮水溶肥料有限公司 | Potassium sulfate particle and preparation method thereof |
| CN105294270B (en) * | 2015-11-11 | 2018-10-09 | 河北萌帮水溶肥料有限公司 | A kind of granular potassium sulfate and preparation method thereof |
| CN112158862A (en) * | 2020-05-15 | 2021-01-01 | 青岛碱业钾肥科技有限公司 | Production method of low-chlorine potassium sulfate |
| CN112158862B (en) * | 2020-05-15 | 2021-06-29 | 青岛碱业钾肥科技有限公司 | Production method of low-chlorine potassium sulfate |
| CN113387372A (en) * | 2021-07-07 | 2021-09-14 | 东南大学 | Method for roughening surface of potassium sulfate particles |
| CN113387372B (en) * | 2021-07-07 | 2022-03-08 | 东南大学 | Method for roughening surface of potassium sulfate particles |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1033157C (en) | 1996-10-30 |
| KR910009598B1 (en) | 1991-11-23 |
| KR880001551A (en) | 1988-04-25 |
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