KR850001175B1 - The method of pelletisation of fertiliser - Google Patents

Abstract

Fertilizer is covered with coating material by a coating machine at 10-250≰C to give a progressive fertilizer. The coating materials are composed of 10-50% silicate soln. (lithium silicate, potassium silicate) by wt. of fertilizer, 0.1-1.0 insoluble metal salt (oxide of Mg, Ca, Fe, Zn and Al or hydroxide or carbonate) by wt. of silicate, 0.05-1.0 soluble metal salt (phosphate of NH4, Na and K, or carbonate or sulfate, carbonate) by wt. of silicate, and 0.05-1.0 minerals by wt. of silicate.

Description

Method of manufacturing long-acting fertilizer

The present invention relates to a method for producing a new and more advanced sustainable fertilizer which has reduced the dissolution rate of fertilizer components in water by coating a liquid mixture in which various additives are added to silicate, which is a main coating agent, to the granular fertilizer.

Chemical fertilizers such as urea, phosphoric acid, kali, and ammonium sulfate, which are widely used at present, are fast-acting fertilizers that are usually quickly dissolved in water. It has been lost due to loss of volatile gas due to decomposition of fertilizers or fixation to soil. The loss of fertilizers affects the growth of crops, which leads to a decrease in yield, as well as economic losses due to the loss of fertilizers and waste of labor for frequent fertilization. Research into the development of sustainable fertilizers in which the dissolution rate can be properly controlled is actively conducted.

The production of long-acting fertilizers can be divided into chemical and physical methods. The former method combines fertilizer chemically with other materials so that this bond is gradually decomposed after fertilization, so that the fertilizer component is continuously released. Urea formaldehyde condensate (US Pat. Nos. 2,830,036, 3,227,543) Crotylidene urea (Crotyliden ediurea) and a condensate of urea acetaldehyde (US Patent No. 3,190,741, UK Patent No. 1,041,537) Hosobutylidenediurea (IBDU) (US Patent No. 3,054,699, Japanese Patent No. 38-7942), Magnesium Ammonium Phosphate (US Pat. Nos. 2,827,368, 3,181,943) and others have been manufactured by this method, but since these products have to combine the fertilizer components with other substances in the production process, the production cost is three to four times that of conventional fertilizers. It has a drawback that has been reached, and has not been put to practical use.

Physical fertilizers can be classified into two methods: mixing and adsorbing conventional fertilizers into appropriate materials, and coating methods for thin coating of granular fertilizers.

Wax, asphalt, petroleum resin (US Pat. No. 3,219,433), polyurethane foams, etc., are mixed-use sustainable fertilizers that use high molecular materials (US Pat. No. 3,232,739) and clay (US Pat. No. 2,991,170) as mixtures. Although it is inexpensive, the dissolution rate of fertilizer is not constant and the content of fertilizer per unit product is low.

On the other hand, the coated sustainable fertilizer is the most suitable method for the practical use of the product because the manufacturing cost is low by the appropriate selection of the coating material, the fertilization rate of the fertilizer is easily controlled, and the fertilizer content can be increased. To date, waxes, polymeric materials and sulfur have been proposed as coating materials that can be used for the production of coated sustainable fertilizers.

Among these coatings, waxes (US Pat. Nos. 3,096,171 and 3,256,786) have hydrophobic properties but require a large amount of wax in the coating, and during the manufacturing process, the wax sticks to the wall of the coating machine or the fertilizer wax There remains a technical problem such as dispersion in the stomach.

Urea-aldehyde condensates (US Pat. Nos. 3,214,259, 3,248,255) in polymer coatings have attracted a lot of attention because they contain nitrogen, but like waxes, they have poor film properties and high water permeability. Have. In addition, Osmocote (US Pat. No. 3,223,518) developed by Archer Daniels Midland Co. of the United States as one of the polymer coating materials is a co-polymer of dicyclopentadiene and glycerol ester. Multi-coating of urea particles as a main component, which has good properties of the product but is expensive and difficult to recover organic solvents used in the manufacturing process.

The use of sulfur as a coating material (US Pat. No. 3,295,950) is described in US Pat. buoy. Developed by T.V.A, molten sulfur was sprayed and coated with urea particles in a rotary furnace and then treated with a sealant. This product uses low-cost sulfur, so the manufacturing cost is low but the coating performance of sulfur is not good and it needs to be additionally coated with sealant to seal cracks in the coating film. There are complex problems, such as the need for further treatment of the regulators to prevent them. In addition, the quality of the product is not uniform, poor shelf life and fertilization when there is a lot of problems such as difficult to control the dissolution rate of fertilizer in the soil by the decomposition of sulfur by microorganisms in the soil.

As described above, the conventional sustainable fertilizer has high production cost, excessive mixture and coating amount, poor coating quality, difficulty in quality control, organic solvent recovery problem, influence by microorganisms in soil, floating on water, The shelf life of products and coating materials have problems such as soil accumulation and its effects.

An object of the present invention is to improve the coating problems by improving the problems described above, and to solve the problems caused by the soil content of the residual fertilizer coating material with a high content of fertilizer components, and the manufacturing process of the new and advanced coating type persistent fertilizer with a simple manufacturing process. To provide.

In the preparation of the sustained fertilizer of the present invention, a simple method for preparing the same is used to coat a surface of a fertilizer particle in a coater with a silicate solution composed of a mixture of a non-aqueous metal salt, a water-soluble metal salt and an inorganic mineral. It is to prepare a long lasting fertilizer useful.

The production method of the present invention will be described in more detail as follows, wherein silicate is used as the main material of the coating material, and the water-insoluble metal salt (hereinafter referred to as the first additive), the water-soluble metal salt (hereinafter referred to as the second additive), and the inorganic mineral (hereinafter referred to) Triadditives) and a mixture of organic polymer materials are coating materials. Here, silicate refers to lithium silicate, sodium silicate, calilicate, ethyl silicate and the like, and these compounds may be used alone or in combination of two or more thereof.

The first additives are magnesium, calcium, iron, zinc, oxides with aluminum, hydroxides, fluorides, carbonates, phosphates or zinc, aluminum, calcium sulfate, ferrosilicon, calcium silicide, calcium sulfite (Calcium Sulfite) ), Calcium silicate fluoride (Calcium Silicofluoride), titanium oxide, silicon oxide powder may be used alone or in combination of two or more. Secondary additives include ammonium, sodium, potassium phosphates, carbonates, fluorides, sulfates, hydroxides, silicofluoride compounds or magnesium, zinc, aluminum, iron chlorides, sulfates, silicofluoride compounds or calcium chloride, sodium Refers to aluminate and lithium hydroxide, which may be used alone or in combination of two or more thereof.

The third additive may be kaolin, vermiculite, zeolite, talc, silica, alumina, feldspar, aluminite, bentonite, and pilite alone or in combination of two or more thereof. Finally, the organic polymer material is gelatin, carrageenan, cellulose derivatives, and the like. When the trace amount of the organic polymer material is added, the uniformity of the coating is improved, but it is not necessary to add it.

When a method of coating the coating material on the fertilizer particles is as follows.

Dissolve in water so that the weight concentration of silicate is 10-50%, then mix the first additive in the aqueous solution so that the weight ratio of silicate is 0.0-1.0 and stir vigorously, and add the amount of silicate and the weight ratio 0.0-1.0 The three additives are mixed and stirred. The second additive is slowly added to the stirring aqueous solution so that the weight ratio with the silicate is 0.0-1.0, and the pH of the final silicate solution is adjusted to 9.0-14.0. The first and third additives are preferably added after grinding into small powders of 100 mesh or less, and the second additive is first dissolved completely in water and then slowly added to the stirring silicate solution. The silicate solution thus prepared is sprayed and coated on the surface of the fertilizer particles in a rotating coating machine rolled by a 0.03-2 cm diameter fertilizer particle or a fluidized bed coater in which the particles are flowed. When the amount of fertilizer to be coated was 500 g, the feed rate of the coating solution was 2.00-20 ml-min; In case of using air-mixed spray nozzle, the air pressure is 0.2-5.0kg / cm ² and the temperature inside the coater is maintained at 20-100 ℃. The process conditions here have a relative influence on each other rather than being controlled by independent variables. For example, complementary effects can be achieved by increasing the coater temperature, reducing the concentration of the solution, decreasing the spray rate, or decreasing the coater temperature while increasing the rotation and fluidization rate depending on the size of the fertilizer particles. In addition, the coating solution must be continuously stirred during the coating, and it is advantageous to allow the initial temperature to be gradually lowered rather than keeping the coating machine temperature constant. After the spraying of the silicate solution, the coated fertilizer particles are subjected to heat treatment for 10 seconds to 10 days under a condition of 5-95% relative humidity and 10-250 ° C. The heat treatment time is longer as the temperature is lower, but it is advantageous here to change the conditions of the early and late rather than maintaining a constant temperature and humidity. The method of injecting carbon dioxide during the heat treatment and the surface treatment of the coated particles with an acidic solution also help to insolubilize the silicate.

As described above, the product manufactured in the present invention does not need solvent recovery because it uses an aqueous solution, and the manufacturing process is simple since the single coating process is performed after mixing various additives with silicate. In addition, since the coating is uniformly formed on the surface of the particles, there is almost no lumping, and no cracking of the coating film occurs, the fertilizer component does not leak through the cracked part after fertilization and the product does not deteriorate even after long-term storage. No heavy weight is required.

On the other hand, the used silicate and various additives are mostly deficient in soil and crops, so the soil accumulation of the coating material when used for a long time improves the soil.

The following examples will illustrate the invention in more detail, but are not intended to limit the scope of the invention.

Example 1

500g of 3-5mm diameter urea particles were put into a fluidized bed coater (Uni-Clatt, Daikogawa, Japan) and the fluidization air velocity was adjusted to 5 × 10 ^-2 m3 / sec to fluidize the urea particles at a temperature of 70 ° C. Preheat for 30 minutes.

An aqueous solution containing 38% by weight of sodium silicate having a weight ratio of silicon oxide / sodium oxide of 3.4 is called solution (1). Water is added to 118.4 g of this solution, diluted to 24% by weight of sodium silicate, and the solution is continuously stirred and sprayed at a nozzle pressure of 1.0 kg / cm ² while feeding to the fluidized bed at a rate of 7 ml / min through a pump. The temperature in the fluidized bed is kept at 70 ° C. during the coating. After the coating is completed, the temperature is lowered to room temperature and then dried for 10 minutes in a fluidized state. There was no agglomeration of particles during the coating, and after the coating was completed, each particle was completely covered with a smooth and transparent film. The coated particles were heated at 40 ° C. for 30 minutes, and then slowly heated up at a rate of 0.5 ° C. per minute to reach 90 ° C., followed by heat treatment for 2 hours while maintaining a temperature of 90-100 ° C. The treated fertilizer was put into water, and the nitrogen dissolution rate after 100 hours was 100%. (In the case of coating using only sodium silicate as described above, the individual particles could be completely covered without entanglement of particles. On the other hand, since the coating absorbed water in water and redissolved, in Example 2 and below, various additives were mixed to silicate. Elution of the fertilizer was alleviated by suppressing re-dissolution of the film.

Example 2

A solution of a mixture of zinc carbonate powder and water in a weight ratio of 65:35 was treated with a ball mill for two weeks. The solution (2) was a solution of 5 g of kaolin powder and 23.4 g of water. A solution obtained by completely dissolving 6 g of potassium phosphate (KH ₂ PO ₄ ) and 6 g of lithium hydroxide in 145.5 g of water was referred to as solution (4). 27.8 g of solution (2) and the total amount of solution (3) were added to 118.4 g of solution (1). After mixing, while stirring, the total amount of the solution (4) was added 20g per minute, and the mixture was stirred for 3 hours. This is called solution (5). Meanwhile, 500 g of urea particles having a diameter of 9 mm were placed in the coating machine, and the urea particles were preheated for 30 minutes at a temperature of 70 ° C. while fluidizing by adjusting the fluidization air speed to 5 × 10 m 3 / sec. 39.5 g of solution (1) is diluted with water to 30% by weight of sodium silicate, and then sprayed with a nozzle pressure of 1.25 kg / cm ² while feeding the solution to the fluidized bed at a rate of 5 ml / min. After spraying, it is maintained for 10 minutes and then the temperature is lowered to 40 ° C., and the whole solution (5) is sprayed on the fluidized particles under the same conditions as before. Thus, the coated particles had a white and opaque film formed on the surface.

The weight composition (part) of the coated particle is as follows. Hereinafter, the weight composition unit will be omitted.

Element (diameter 8-10 mm) 500 kaolin 5

Sodium Silicate 60 Calcium Phosphate 6

Zinc carbonate 18 lithium hydroxide 6

Example 3

The particles prepared in Example 2 were left in air for 1 week and then heat treated. Heat treatment at 40 ℃ for 1 hour, 50 ℃ for 30 minutes, 60 ℃ for 30 minutes, then slowly increase the temperature at a rate of 0.5 ℃ per minute to reach 90 ℃, and then heat for 4 hours while maintaining the temperature of 90-100 ℃. It was. The treated particles were placed in water and observed, and the particles were all submerged and the nitrogen dissolution rate was as follows.

Example 4

Urea particles 1-2 mm in diameter were coated as in Example (2). Some of the particles agglomerated slightly during the coating, but the amount did not matter below 1/20 of the total particles. Urea particles 3-5 mm in diameter were coated in the same manner as in Example (2), but only the nozzle pressure was changed to 0.75 kg / cm ² . There was no lumping phenomenon during coating. The coated particles were heat treated as in Example (3) and after 24 hours, the nitrogen dissolution rate in water was as follows.

Example 5

300 g of the product prepared in Example (3) and Example (4) were put in a polyethylene bag and stored at room temperature for 3 months with a weight of 1 kg placed thereon. As a result of measuring the elution rate of nitrogen by the same method, it was found that it did not change with the case before storage, and thus the storage capacity of the product was excellent.

Example 6

263.2 g of silicate silicate with a solid concentration of 38% and a weight ratio of silicon oxide / caliper oxide of 2.57 and 132.6 of water are added to the flask, and the volatile solution is heated to 90 ° C. under reflux with a condenser. 15 g of fine silicon oxide is added thereto and heated for 4 hours with vigorous stirring to obtain a completely homogeneous solution, which is called solution (6). 5.0 g of phosphate (K ₂ HPO ₄ ) and 1.2 g of hydroxide were dissolved in 18.1 g of water (7), 0.84 g of lead chloride was dissolved in 70.0 g of water (8), 8 g of talc and 10 g of titanium oxide. The solution mixed with 62 g of water is called (9). 337.3 g of the solution (6) and the whole solution (9) were mixed to obtain a fully dispersed solution by vigorous stirring, followed by stirring for 10 minutes by adding the entire solution (7) and (8) to the solution (10). The coating experiment similar to Example (2) was performed using the solution (10) instead of the solution (5) in Example (2). The coated particles were left in the air for 1 week, then heat treated at 40 ° C. for 2 hours, 70 ° C. for 30 minutes, and then heat-treated again at 90-100 ° C. for 15 minutes in an airtight container. The temperature of ℃ was maintained. The weight composition of the coated particle film with respect to 500g of urea is as follows and it was measured to elute 2.5% of nitrogen after 24 hours in water.

Hydrogen Silicate 15 Zinc Chloride 0.4

Caliber Silicate 47 Talc 4.0

Calcium Phosphate 2.5 Titanium Oxide 5.0

Hydroxide 0.6

Example 7

10 g of alumina oxide, 7 g of calcium phosphate, 8 g of magnesium phosphate, 3 g of calcium carbonate, 1 g of alumina sulfide, 0.8 g of zinc silico fluoride, 0.4 g of potassium silico fluoride, and 2 g of bentonite were washed with 48.3 g of water at 150 ° C. for 2 hours at 150 ° C. Heated for 2 hours at 400 ° C. for 3 hours, and then pulverized to 100 mesh or less, 16.1 g of which was mixed with 4 g of zinc oxide and 0.8 g of sodium polyphosphate, and then made into an aqueous solution having a concentration of 30%. do. A solution (12) is a solution in which the total amount of the solution (11) and 118.4 g of the solution (1) are mixed and diluted to 20%. The solution 5 in Example (2) was replaced with the solution 12, and the same coating as in Example (2) was performed, and the same heat treatment as in Example (3) was performed. The treated particles were soaked in a wire mesh for 30 minutes in a 50% phosphoric acid solution, taken out, dried in air for 3 days, and then treated at 50 ° C. for 2 hours. The weight composition of the coating material for 500g of urea and the nitrogen elution in water after 24 hours are as follows.

Hydrogen Silicate 60 Zinc Silicofluoride 0.4

Alumina Oxide 5 Potassium Silicofluoride 0.2

Potassium Phosphate 3.5 Zinc Oxide 4

Magnesium Phosphate 4 Sodium Polyphosphate 0.8

Alumina Chloride 0.5 Bentonite 1

Calcium carbonate 1.5 Nitrogen elution after 3.8 hours = 3.8%

Example 8

13.5 g of zinc oxide (1st additive), 0.8 g of calcium fluoride, and 70 g of water were mixed and treated with a ball mill for one week. (13). 3 g of calcium phosphate, 0.2 g of magnesium chloride, and 0.4 g of iron sulfide were added. The solution completely dissolved in 36 g is referred to as (14). The total amount of the solution 13 and 3 g of the kaolin powder, which is the third additive, are mixed with 118.4 g of the solution (1). The solution 5 in Example (2) was replaced with the solution 15, and the same coating as in Example (2) was performed, and the same heat treatment as in Example (3) was performed. The weight composition of the coated particle film with respect to 500 g of urea and the nitrogen dissolution rate in water for 24 hours are as follows.

Hydrogen Silicate 60 Calcium Fluoride 0.8

Zinc Oxide 13.5 Magnesium Chloride 0.2

Kaolin 3 iron sulfide 0.4

Calcium Phosphate 3 24 Hour Nitrogen Dissolution Rate = 1.9%

From Example (9) to Example (13), the additives were changed in various ways, and the experimental method was performed in the same manner as in Example (8).

Example 9

Sodium silicate 60 talc 3

Zinc Carbonate 13.5 Ammonium Phosphate 0.3

Aluminum Hydroxide 4 Carrageenan 0.2

Calcium hydroxide 1.2 Nitrogen dissolution rate after 24 hours = 7.1%

Example 10

Sodium silicate 60 zeolite 2

Zinc Carbonate 13.5 Magnesium Silicon Fluoride 0.8

Titanium Oxide 6 Aluminum Sulfide 0.2

Kaolin 4 Nitrogen dissolution rate after 24 hours = 2.6%

Example 11

Sodium silicate 45 kaolin 3

Zinc powder 9 Sodium aluminate 1

Calcium phosphate 6 Nitrogen dissolution rate after 24 hours = 1.8%

Magnesium hydroxide 2

Example 12

Sodium silicate 60 talc 3

Alumina Phosphate 12 Sodium Silicon Fluoride 0.4

Magnesium Oxide 6 Zinc Sulfide 0.4

Nitrogen dissolution rate after silicon oxide 3 = 24%

Calcium sulfite 3

Example 13

Hydrogen Silicate 60 Aluminum Fluoride 0.4

Iron oxide 12 kaolin 3

Magnesium Carbonate 6 Ammonium Carbonate 0.4

Nitrogen dissolution rate after 24 hours of zinc phosphate = 8.9%

Example 14

Yujong layer coated group of nitrogen, the weight ratio of phosphoric acid, potassium 18 are 3-5mm in diameter (Uni-Glatt, Japan大川原Corporation): 18: a fertilizer particle composition of 18 to 5 × 10 500g into the fluidizing air velocity ^- Nitrogen, phosphoric acid at a temperature of 70 ℃ while controlling to ² m3 / sec fluidized. Preheat the composite fertilizer particles with a Kali weight ratio of 18:18:18 for 30 minutes. An aqueous solution containing 38% by weight of a compound fertilizer sodium silicate having a weight ratio of silicon oxide / sodium oxide of 3.4 is called solution (1). Dilute the weight of sodium silicate to 24% by adding water to 118.4 g of the solution, and continue to stir, spraying with a nozzle pressure of 1.0 kg / cm ² while supplying the fluidized bed at a rate of 7 ml / min through a pump. The temperature in the fluidized bed is kept at 73 ± 2 ℃ during the coating. After the coating is completed, the temperature is lowered to room temperature and dried for 10 minutes in a fluidized state. There was no agglomeration of particles during the coating, and after the coating was completed, each particle was completely covered with a smooth and transparent film. The coated particles were heated at 40 ° C. for 30 minutes, and then slowly heated at a rate of 0.5 ° C. per minute to reach 90 ° C., and then heat-treated for 1 hour 30 minutes while maintaining a temperature of 95 ± 5 ° C. The treated fertilizer was put in water, and the fertilizer dissolution rate after 100 hours was 100%.

Claims (1)

In the preparation of long-acting fertilizers, the aqueous solution of silicate at a concentration of 10-50% weight in the fertilizer and the non-aqueous metal salt of fertilizer 0.1-1.0 in weight, the inorganic mineral in the weight ratio of 0.0 5-1.0 in silicate and silicate Method for producing a sustainable fertilizer, characterized in that the coating material at 0.05-1.0 water-soluble metal salt in weight ratio at a temperature of 10-250 ℃ in a coater Here, silicate refers to lithium silicate, sodium silicate, calilicate, and ethyl silicate, which may be used alone or in combination of two or more thereof. Water-insoluble metal salts include oxides, hydroxides, fluorides, carbonates, phosphates or zinc, aluminum, calcium sulfate, ferrosilicone, calcium silicides, calcium sulfides, calcium silicofluorides, oxides with magnesium, calcium, iron, zinc, and aluminum. Titanium and silicon oxide may be used alone or in combination of two or more thereof. Water-soluble metal salts include phosphates, carbonates, fluorides, sulfates, hydroxides, silicofluoride compounds with ammonium, sodium and potassium, chlorides with magnesium, zinc, aluminum and iron, sulfates, silicofluoride compounds or calcium chloride, sodium aluminate It can be used alone or in combination of two or more. Inorganic minerals refer to kaolin, vermiculite, zeolite, silica, alumina, feldspar, aluminite, bentonite, and pilite, which may be used alone or in combination of two or more.