CN1793064A - Pelletization of lemery salt - Google Patents

Abstract

The present invention relates to granular potassium sulfate (SOP) products and methods of producing granular SOP. More particularly, the present invention relates to granulated SOP and a method of making granulated SOP using cornstarch as a binder.

Description

Granulation of Potassium Sulfate

technical field

The present invention relates to granular potassium sulfate (SOP) products and methods of producing granular SOP. More particularly, the present invention relates to granulated SOP and a method of making granulated SOP using cornstarch as a binder.

Background technique

Plants are able to obtain some of the nutrients they need, such as carbon, hydrogen and oxygen, from the atmosphere and water. Other essential nutrients such as nitrogen, phosphorus and potassium may be obtained from the soil.

Often, these nutrients are lacking in the soil or are present in forms that are not readily available to plants. Accordingly, methods have been developed to provide plants with these and other nutrients needed for productive growth. These plant nutrients can be provided in the form of fertilizers containing the desired nutrients added to the soil.

Fertilizer products can be mononutrient or multinutrient products. Multi-nutrient products are known as composts or compound fertilizers and can be blended fertilizer products. Fertilizers can come in many forms including powder, liquid or granules. Fertilizers in powder form are common in agriculture. However, if a blended fertilizer product is to be manufactured, a granular fertilizer product is required to prevent separation of the blended fertilizer and to prevent excessive dust generation.

SOP is an excellent source of potassium for crops. Various grades of SOP generally contain about 50% to 54% _K2O , and SOP also contains about 17% sulfur. Although lower _K2O contents are also possible, this is not desirable after all. Usually based on the reaction of KCl and _H2SO4 or the evaporation or crystallization of brine from natural salt lakes _, the recrystallization method is used to manufacture SOP. SOP is a widely used fertilizer because of, for example, its low chlorine content and water solubility. Furthermore, SOPs provide crops with high concentrations of readily available nutrients.

Due to the loose and unconsolidated nature of SOP fertilizers, they are often processed in powder form and conventional granulation techniques cannot be used to make SOP fertilizers into granules with sufficient chemical and physical properties. In granular SOP, it is difficult to obtain sufficient water content and nutrient analysis results (high potassium content). Also, in granular SOP, it is difficult to obtain satisfactory surface smoothness and hardness.

However, granular SOP is suitable for use in the production of bulk blend fertilizers due to its relatively uniform particle size that is compatible with other raw materials such as granular urea and phosphate. Bulk blended fertilizers with different particle sizes can easily lead to separation or separation of their components.

Separation of fertilizer components may occur during blending, transportation, storage and application of fertilizers. Application of separated products/fertilizers may result in uneven distribution of nutrients, which is undesirable. A granular form having the same particle size range as the other components of the blended fertilizer can avoid segregation problems of the fertilizer components.

Conventional granulation technology methods include granulation of SOP with clay as a binding material. Due to the chemical nature of crystalline SOP, SOP molecules tend to repel each other, making granulation of sufficient quality difficult with conventional binders such as clay. Nevertheless, there have been attempts to manufacture granular SOPs using pressure and clay as a binder.

The use of clay as binding material resulted in low _K2O analysis results ( _K2O below 40%) and made the fertilizer formulation procedure difficult due to the low content of potassium. Furthermore, the granular structure using clay as a binding material can lead to disintegration of the particles, excessive dusting and poor solubility. Nevertheless, clay can still be used as a binder for SOP; it can account for up to 20% of the total SOP product.

Contents of the invention

In one aspect, the invention relates to a method of producing a granular SOP product, the method comprising comminuting the SOP, usually in powder form. The method comprises preparing a suspension of cornstarch and water, and spraying said suspension of cornstarch and water on the pulverized SOP. The suspension of cornstarch and water acts as a binder and facilitates granulation of the SOP. Up to about 4.0% by weight cornstarch relative to the SOP is mixed with the SOP.

Drying and packaging of granular SOP. Optionally, the granular SOP particles can be coated to help prevent the particle from disintegrating. In another aspect, the present invention relates to granular SOP compositions.

Description of drawings

Figure 1 is a flow chart describing an embodiment of a method of manufacturing a granulated SOP product; the figure also shows a granulation system for the SOP.

Detailed ways

The present invention relates to the use of starch as a binder to form powdered SOP into granules with desired chemical and physical properties. In particular, the present invention relates to the use of cornstarch as a binder in the granulation of SOPs.

The SOP may be provided in powder form and may contain at least 50% _K2O . The granulation technique of the present invention uses a minimal amount of cornstarch to granulate SOP micropowder to produce granulated SOP with high potassium (K) content. Potassium content can be over 48.0% _K2O . Granular SOP with cornstarch binder results in granulated SOP with good granule hardness, good structure, uniform particle size, no dust, and is a highly water-soluble product.

SOP can be produced by various methods including treating caustic potash or potassium carbonate (K ₂ CO ₃ ) with sulfuric acid (H ₂ SO ₄ ), reacting sulfuric acid with potassium chloride (KCl) or treating it with magnesium sulfate or sulfuric acid Handling Potassium Chloride (MOP). For certain crops, SOP is the preferred fertilizer that not only provides potassium but also does not contain high levels of chlorine. For example, MOP has higher levels of chlorine than SOP, which can be harmful to certain plants or crops. For example, high chlorine levels in the soil can have adverse effects on tobacco plants.

SOP fertilizers are generally loose and unconsolidated in nature and are therefore often handled in powder form, but generally cannot be granulated with sufficient chemical qualities such as nutrient content and moisture content. Furthermore, it is often difficult to granulate SOP with sufficient physical qualities such as particle structure, surface smoothness and hardness.

Due to the chemical nature of crystalline SOP, SOP molecules tend to repel each other, making high quality granulation difficult with conventional binders such as clay. Attempts have been made to granulate SOP by applying pressure and using clay as a binder. However, SOP produced by this method may result in SOP with lower potassium content ( _K2O less than 40%). Furthermore, the use of pressure and the use of clay as a binder resulted in poor particle structure, manifested by particle decomposition, excessive dusting, and low water solubility.

Referring to FIG. 1 , SOP powder is first weighed and loaded into a container 102 , at which point the SOP is pulverized 104 . Comminuting 104 the SOP breaks up any bulky SOP powder so that, for example, the proper particle size can be formed and a suitable surface area of powdered SOP can be obtained for binding with starch. The particle size of the SOP powder is less than 1.0 mm in diameter, preferably less than about 0.6 mm in diameter, more preferably less than 0.4 mm in diameter.

The starch binder 110 was weighed and placed in another container. The starch binder (in this case cornstarch) is mixed 112 with warm water. The cornstarch is mixed during the addition of warm water 116 to the vessel. The water temperature may be from 20°C to 60°C, preferably from 45°C to 55°C, and more preferably about 50°C.

Steam 114 may be added to the vessel containing the cornstarch and water mixture to heat the mixture to a temperature of at least 70°C. The cornstarch is preferably mixed 112 with warm water and dissolved to form a cornstarch-water suspension. The mixing time of the cornstarch-water suspension depends on the volume of the container.

Transfer the heated cornstarch-water suspension from the mixing vessel to the nozzle of the granulator. While the SOP was being mixed in the granulator, the cornstarch suspension was evenly sprayed onto the SOP. The cornstarch suspension can be sprayed on the SOP using a gear pump. The granulator aggregates the finer SOP particles into larger free-flowing granules of powdered SOP coated with starch.

The cornstarch-water suspension can be sprayed into the SOP fluidized powder using a top spray granulator. The temperature of the granulator during the spraying of the cornstarch-water suspension and the granulation 106 of the SOP can be maintained at about 50°C to 70°C, and preferably about 60°C. With continued mixing using the granulator, more powdered SOP is bound by the cornstarch-water suspension to form more SOP granules 106 . The granulation time is from about 5 minutes to about 20 minutes, and preferably from 7 minutes to 15 minutes.

Drying 108 is then performed by hot air 124 flowing into the dryer as the aggregated SOP continues to mix. The granular SOP 106 is dried 108 at a temperature of about 70°C to 100°C, and preferably about 85°C. Granular SOP can be dried with a rotary drying drum. The drying time of granular SOP in the dryer is half an hour. After the SOP particles are dried 108, the SOP particles are dedusted 118, and the dust is collected and washed 122. Dust can be removed with cyclone dust collectors and Vencuri scrubbers. The SOP dust wash liquor is recovered and added to water 116 which is used to dissolve 112 the cornstarch and form a cornstarch-water suspension.

When the dry SOP particles are sufficient, the SOP particles are cooled 126 to a temperature below about 45°C, preferably below about 40°C. Again the SOP particles are dedusted 120 and the dust is collected and washed 122 . The wash liquor containing the SOP dust is recovered and used as part of the water 122 to mix and dissolve the cornstarch 112 and form a cornstarch-water suspension.

The SOP granules are screened 128, whereby SOP granules of the appropriate size are obtained. A sieve can be used to obtain granular SOP of about 2 mm to 4 mm. The SOP can be sieved 128 with a 5-9 mesh Taylor sieve, so as to obtain the SOP with a particle size of 2mm-4mm. The powder material remaining after sieving is reused by adding the powder SOP to the crushing step 104 . The granular SOP thus obtained may have a grain hardness of at least 15 Newtons.

The granulated and cooled SOP particles enter the coating drum 138 and are coated 134 with a coating agent. The coating agent is dissolved and heated with a steam coil in vessel 132 before being sprayed onto the surface of the particles. The pellets then enter the finished product bin 140 for bagging. Dust in the system is removed by dust removal systems 142 and 146 for reuse.

Example

Trial 1 - Preparation of Granular SOP with Corn Starch Binder

This method describes the preparation of granular SOP from SOP powder and a cornstarch binder based on the method described here.

About 1,200 grams of powdered SOP with a particle size of less than 1 mm was added to the granulator. Powdered SOP typically has a particle size of less than 1 mm. Put about 40g of cornstarch in a container and mix it thoroughly with about 40ml of warm water. The temperature of the water is about 50°C. The cornstarch-water suspension was then artificially heated to a temperature of about 70°C while stirring. When the cornstarch-water suspension reached a temperature of about 70°C and was thoroughly mixed, the cornstarch-water suspension was transferred to the sprayer.

Start the granulator with the weighed SOP sample and spray the cornstarch-water suspension evenly onto the SOP. Pan granulators or drum granulators can be used. In this example, a disc granulator was used for SOP granulation. The rotational speed of the granulator was set at 13 rpm to 17 rpm. The cornstarch-water suspension was used as a binder and the granulator was started to aggregate the powdered SOP to form granules. During granulation, the temperature of the SOP and cornstarch-water suspension was about 60°C.

After the SOP granules were formed, the granulator was stopped, and the SOP product was sieved with a Taylor type sieve to obtain SOP granules with a size of 2 mm to 4 mm. The material is then dried in an oven at a temperature of about 300°C. The granulation time of SOP is 7 minutes to 15 minutes, and it takes about 4 hours to dry granulated SOP.

After the granular SOP is formed, the granular SOP is analyzed. According to the analysis results of granular SOP, K ₂ O is about 48.51%, and the moisture content is about 0.11%. The granule hardness of the granulated SOP was 15.9 Newtons when cornstarch was used as the binder.

Trial 2 - Preparation of Granular SOP with Corn Starch Binder

This method describes the preparation of granular SOP from SOP powder and a cornstarch binder based on the method described here.

About 1,050 grams of powdered SOP having a particle size of less than about 1 mm was placed into the granulator. Add about 25 grams of cornstarch to the container and allow it to mix thoroughly with about 25 ml of warm water. The temperature of the water is about 50°C. The cornstarch-water suspension was then heated to a temperature of about 70°C while stirring. When the cornstarch-water suspension reached a temperature of about 70°C and was thoroughly mixed, the cornstarch-water suspension was transferred to the sprayer.

Start the granulator with the weighed SOP sample and spray the cornstarch-water suspension evenly onto the SOP. Pan granulators or drum granulators can be used. In this example, a disc granulator is used for SOP granulation. The rotational speed of the granulator was set at 13 rpm to 17 rpm. The cornstarch-water suspension was used as a binder and the granulator was started to aggregate the powdered SOP to form granules. During granulation, the temperature of the SOP and cornstarch-water suspension was about 60°C.

After the SOP granules are formed, the granulator is stopped, and the SOP product is sieved with a Taylor-type sieve to obtain SOP granules with a particle size of 2 mm to 4 mm. The material was then dried in an oven at a temperature of about 300°C. The granulation time of SOP is 7 minutes to 15 minutes, and it takes about 4 hours to dry granulated SOP.

After the granular SOP is formed, the granular SOP is analyzed. According to the analysis results of granular SOP, K ₂ O is about 49.4%, and the moisture content is about 0.66%. The granule hardness of the granulated SOP was 15.9 Newtons when cornstarch was used as the binder.

The potassium content of granular SOP was determined by the method of ISO5318. Moisture content was determined gravimetrically. A granular SOP sample is heated to dryness and the moisture loss is calculated from the measured weight of the sample before and after drying.

The standard test method for hardness of fertilizer granules was used to determine the hardness (or compressive strength) of granular SOP. Granular SOP samples were sieved according to IFDC S-107 to obtain at least 25 granules of close size classes. The particle size used for experimental analysis ranges from 2.36mm to 2.80mm. The hardness was measured with a commercially available compression tester. A single pellet is placed on the mounted surface and pressure is applied using the flat-ended rod supplied with the compression tester. The pressure required to break the granules is determined by a gauge mounted on a compression tester. At least 25 particles were tested and the average value of the measurements was taken as the hardness of the particles.

The above embodiments are intended to describe the present invention, not to limit the present invention. Other embodiments are also within the claims. Although the present invention has been described with reference to specific embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims (19)

1. the Ru 2006101161 that contains vitriolate of tartar and W-Gum.

2. Ru 2006101161 as claimed in claim 1, wherein, described W-Gum is as the tackiness agent of vitriolate of tartar particle.

3. Ru 2006101161 as claimed in claim 1, wherein, described vitriolate of tartar and W-Gum form vitriolate of tartar-corn starch granules together.

4. Ru 2006101161 as claimed in claim 1, wherein, when making up with described W-Gum, described vitriolate of tartar is in powder type.

5. Ru 2006101161 as claimed in claim 4, wherein, described W-Gum is the suspension of W-Gum and water.

6. Ru 2006101161 as claimed in claim 1, with respect to the weight of vitriolate of tartar, this Ru 2006101161 contains the W-Gum that is no more than 4 weight %.

7. Ru 2006101161 as claimed in claim 1, wherein, the K2O content of vitriolate of tartar-corn starch granules is at least 47%.

8. Ru 2006101161 as claimed in claim 3, wherein, described vitriolate of tartar-corn starch granules has at least 14 newton's pellet hardness.

9. the method for production particulate state vitriolate of tartar, this method comprise vitriolate of tartar and W-Gum combination.

10. method as claimed in claim 9 wherein, will be no more than W-Gum and the combination of described vitriolate of tartar of 4.0 weight % with respect to vitriolate of tartar.

11. method as claimed in claim 9, wherein, described W-Gum provides with the form of the suspension of W-Gum-water, and the suspension of described W-Gum-water contains the W-Gum and the water of roughly the same umber.

12. method as claimed in claim 11 wherein, is sprayed described vitriolate of tartar by the suspension with W-Gum-water and is formed the particulate state vitriolate of tartar.

13. method as claimed in claim 11 wherein, before the suspension combination with described vitriolate of tartar and described W-Gum-water, is pulverized described vitriolate of tartar.

14. method as claimed in claim 12, wherein, with described particulate state vitriolate of tartar drying.

15. method as claimed in claim 14 wherein, is sieved described particulate state vitriolate of tartar.

16. method as claimed in claim 15, wherein, the minimum size of described particulate state vitriolate of tartar is about 2 millimeters.

17. method as claimed in claim 15, wherein, the overall dimension of described particulate state granular potassium sulfate is about 6 millimeters.

18. method as claimed in claim 15 wherein, is sprayed described particulate state vitriolate of tartar with the suspension of W-Gum-water, makes on the described granular potassium sulfate and forms coating layer.

19. method as claimed in claim 18, wherein, with described granular potassium sulfate drying through coating.

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