Environmentally friendly slow-release compound fertilizer and preparation method thereof

Abstract

The present invention provides an environmentally friendly slow-release compound fertilizer, aiming to provide an environmentally friendly slow-release compound fertilizer with controllable release rate and high cost-effectiveness. The compound fertilizer is composed of calcium magnesium phosphate fertilizer, urea, potash fertilizer, monoammonium phosphate, borax, zinc sulfate, glycine iron, ammonium molybdate, glycine copper, liquid ammonia, sulfuric acid, liquid paraffin and a slow-release agent, wherein the potash fertilizer is one or two of potassium sulfate and potassium chloride. The present invention also provides a preparation method of an environmentally friendly slow-release compound fertilizer, comprising four steps of preliminary coating, uniform mixing, secondary coating granulation and fluidized bed reaction film formation. The slow-release agent is composed of castor oil, polyoxypropylene triol, polymerized MDI and modified silicon dioxide, and the modified silicon dioxide is obtained by specific chemical treatment. The environmentally friendly slow-release compound fertilizer has the advantages of uniform nutrient release, long effective release period, and environmental friendliness, is suitable for improving fertilizer utilization and reducing environmental pollution, and has good market application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizers, and in particular to an environmentally friendly slow-release compound fertilizer.

[0002] The invention also relates to a method for preparing an environmentally friendly slow-release compound fertilizer. Background Art

[0003] In modern agricultural production, in order to improve fertilizer utilization and reduce environmental pollution, the development of environmentally friendly slow-release compound fertilizers has become an important research direction. Slow-release compound fertilizers can gradually release nutrients over a certain period of time to meet the needs of crop growth while reducing fertilizer loss and environmental pollution. In the prior art, there are various methods for preparing slow-release compound fertilizers, but there are often problems such as inaccurate release rate control and high cost.

[0004] The patent with application number CN202010580423.0 relates to a method for producing compound fertilizer, which belongs to the field of fertilizer technology. The technical problem solved by the present invention is to provide a method for producing compound fertilizer, which has a simple process and low cost. The method obtains compound fertilizer by chelation-ammoniation-mixing granulation process. The method of the present invention has a simple preparation process, safe operation, and low production cost. It can be applied to wet-process phosphoric acid of various concentrations and to prepare compound fertilizers with various different proportions of nitrogen, phosphorus, potassium and trace elements necessary for plant growth. The present invention can effectively increase the water-soluble phosphorus content in compound fertilizers and activate the trace elements necessary for plant growth. The present invention can make full use of impurity ions in wet-process phosphoric acid, such as iron, magnesium, calcium, etc., to prevent phosphorus precipitation during the configuration of compound fertilizers.

[0005] However, the compound fertilizer in the above patent technology also has problems such as inaccurate release rate control and high cost. Therefore, it is of great practical significance to develop a cost-effective, environmentally friendly, environmentally friendly slow-release compound fertilizer and its preparation method. Summary of the invention

[0006] The object of the present invention is to provide an environmentally friendly slow-release compound fertilizer to solve the problems raised in the above background technology:

[0007] (1) How to achieve an environmentally friendly slow-release compound fertilizer with controllable release rate and high cost-effectiveness.

[0008] The purpose of the present invention is to provide a method for preparing an environmentally friendly slow-release compound fertilizer to solve the problems raised in the above background technology:

[0009] (1) How to improve the sustained-release and encapsulation processes so that the preparation method has the advantages of low cost, good effect, and environmental friendliness.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for preparing an environmentally friendly slow-release compound fertilizer comprises the following raw materials in parts by weight:

[0012] Calcium magnesium phosphate fertilizer 260-340 parts, urea 160-260 parts, potash fertilizer 230-360 parts, monoammonium phosphate 90-130 parts, borax 6-12 parts, zinc sulfate 2-6 parts, glycinate iron 1-5 parts, ammonium molybdate 1-5 parts, glycinate copper 1-5 parts, liquid ammonia 20-30 parts, sulfuric acid 20-30 parts, liquid paraffin 2-3 parts, slow-release agent 1-2 parts;

[0013] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following steps:

[0014] a) using 1 / 3 to 1 / 2 of the total amount of powdered calcium magnesium phosphate fertilizer as both a base fertilizer and a binder, mixed with urea, 1 / 3 to 1 / 2 of the total amount of potash fertilizer and monoammonium phosphate for preliminary coating to obtain a primary coated granular fertilizer;

[0015] b) uniformly mixing the primary coated granular fertilizer obtained in step a) with borax, zinc sulfate, iron glycinate, ammonium molybdate, copper glycinate, and the remaining potash fertilizer, and then adding the remaining powdered calcium magnesium phosphate fertilizer, liquid ammonia, and sulfuric acid for secondary coating and granulation to achieve multi-layer coating to obtain secondary coated granular fertilizer;

[0016] c) adding the secondary coated granular fertilizer obtained in step b) into a fluidized bed for preheating, then adding all the liquid paraffin for lubrication, and finally spraying the slow-release agent into the fluidized bed to react and form a film on the surface of the secondary coated granular fertilizer, repeating the addition for 3 times and reacting for a certain period of time to obtain the environmentally friendly slow-release compound fertilizer.

[0017] Based on the above technical solution, the present invention can also be improved as follows.

[0018] Furthermore, the raw materials of the sustained-release agent include castor oil, polyoxypropylene triol, polymerized MDI and modified silica. Under room temperature, polyoxypropylene triol, castor oil and modified silica are stirred and mixed at a mass ratio of 4:1:0.15 at high speed, and then a defoaming agent is added dropwise, and finally stirred and mixed with polymerized MDI to obtain a sustained-release agent.

[0019] Furthermore, the modified silica is mixed with ethanol and distilled water in a volume ratio of 9:1, a certain amount of γ-aminopropyltriethoxysilane is added, and ammonia water is added dropwise to adjust the pH to 8-10. At room temperature, silica is added and stirred continuously; then the modified silica is washed with anhydrous ethanol, filtered, and dried to obtain the modified silica.

[0020] Furthermore, the potash fertilizer is one or both of potassium sulfate and potassium chloride.

[0021] To achieve the above object, the present invention also provides the following technical solutions:

[0022] An environmentally friendly slow-release compound fertilizer is prepared by the method for preparing the environmentally friendly slow-release compound fertilizer.

[0023] Compared with the existing technology, this environmentally friendly slow-release compound fertilizer has the following beneficial effects:

[0024] (1) By precisely controlling the formula and encapsulation process of the slow-release agent, the nutrients in the fertilizer are slowly released, the fertilizer utilization rate is improved, and environmental pollution is reduced.

[0025] (2) The raw material cost is low, the preparation method is simple, and it is easy to produce on a large scale, which has good economic benefits.

[0026] (3) The combined use of fluidized bed technology and slow-release agents improves the surface quality and slow-release performance of fertilizer particles, and enhances the applicability and environmental adaptability of fertilizers. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] Embodiment 1

[0030] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following raw materials in parts by weight:

[0031] 260 parts of calcium magnesium phosphate fertilizer, 160 parts of urea, 230 parts of potassium sulfate, 90 parts of monoammonium phosphate, 6 parts of borax, 2 parts of zinc sulfate, 1 part of glycinate iron, 1 part of ammonium molybdate, 1 part of glycinate copper, 20 parts of liquid ammonia, 20 parts of sulfuric acid, 2 parts of liquid paraffin, and 1 part of slow-release agent.

[0032] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following steps:

[0033] a) using 1 / 3 of the total amount of powdered calcium magnesium phosphate fertilizer as both a base fertilizer and a binder, mixed with urea, 1 / 3 of the total amount of potash fertilizer and monoammonium phosphate for preliminary coating to obtain a primary coated granular fertilizer;

[0034] b) uniformly mixing the primary coated granular fertilizer obtained in step a) with borax, zinc sulfate, iron glycinate, ammonium molybdate, copper glycinate, and the remaining potash fertilizer, and then adding the remaining powdered calcium magnesium phosphate fertilizer, liquid ammonia, and sulfuric acid for secondary coating and granulation to achieve multi-layer coating to obtain secondary coated granular fertilizer;

[0035] c) Preparation of sustained-release agent: The raw materials of the sustained-release agent include castor oil, polyoxypropylene triol, polymerized MDI and modified silicon dioxide. Under room temperature, polyoxypropylene triol, castor oil and modified silicon dioxide are stirred and mixed at a mass ratio of 4:1:0.15 at high speed, and then a defoaming agent is added dropwise, and finally stirred and mixed with polymerized MDI to obtain a sustained-release agent.

[0036] Preparation of modified silica: Mix ethanol and distilled water in a volume ratio of 9:1, add a certain amount of γ-aminopropyltriethoxysilane (analytical grade), add ammonia water to adjust the pH to 8-10, add silica at room temperature and continue stirring; then wash with anhydrous ethanol, filter, and dry in an oven to obtain modified silica.

[0037] The secondary coated granular fertilizer obtained in step b) is added to the fluidized bed for preheating, and then all the liquid paraffin is added for lubrication. Finally, the slow-release agent is sprayed into the fluidized bed to react and form a film on the surface of the secondary coated granular fertilizer. The addition is repeated 3 times and the reaction is carried out for a certain period of time to obtain the environmentally friendly slow-release compound fertilizer.

[0038] Embodiment 2

[0039] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following raw materials in parts by weight:

[0040] 340 parts of calcium magnesium phosphate fertilizer, 260 parts of urea, 360 parts of potassium chloride, 130 parts of monoammonium phosphate, 12 parts of borax, 6 parts of zinc sulfate, 5 parts of glycinate iron, 5 parts of ammonium molybdate, 5 parts of glycinate copper, 30 parts of liquid ammonia, 30 parts of sulfuric acid, 3 parts of liquid paraffin, 2 parts of slow-release agent;

[0041] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following steps:

[0042] a) using 1 / 2 of the total amount of powdered calcium magnesium phosphate fertilizer as both a base fertilizer and a binder, mixed with urea, 1 / 2 of the total amount of potash fertilizer and monoammonium phosphate for preliminary coating to obtain a primary coated granular fertilizer;

[0043] b) uniformly mixing the primary coated granular fertilizer obtained in step a) with borax, zinc sulfate, iron glycinate, ammonium molybdate, copper glycinate, and the remaining potash fertilizer, and then adding the remaining powdered calcium magnesium phosphate fertilizer, liquid ammonia, and sulfuric acid for secondary coating and granulation to achieve multi-layer coating to obtain secondary coated granular fertilizer;

[0044] c) Preparation of sustained-release agent: The raw materials of the sustained-release agent include castor oil, polyoxypropylene triol, polymerized MDI and modified silicon dioxide. Under room temperature, polyoxypropylene triol, castor oil and modified silicon dioxide are stirred and mixed at a mass ratio of 4:1:0.15 at high speed, and then a defoaming agent is added dropwise, and finally stirred and mixed with polymerized MDI to obtain a sustained-release agent.

[0045] Preparation of modified silica: Mix ethanol and distilled water in a volume ratio of 9:1, add a certain amount of γ-aminopropyltriethoxysilane (analytical grade), add ammonia water to adjust the pH to 8-10, add silica at room temperature and continue stirring; then wash with anhydrous ethanol, filter, and dry in an oven to obtain modified silica.

[0046] The secondary coated granular fertilizer obtained in step b) is added to the fluidized bed for preheating, and then all the liquid paraffin is added for lubrication. Finally, the slow-release agent is sprayed into the fluidized bed to react and form a film on the surface of the secondary coated granular fertilizer. The addition is repeated 3 times and the reaction is carried out for a certain period of time to obtain the environmentally friendly slow-release compound fertilizer.

[0047] Embodiment 3

[0048] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following raw materials in parts by weight:

[0049] 300 parts of calcium magnesium phosphate fertilizer, 200 parts of urea, 300 parts of potassium sulfate, 110 parts of monoammonium phosphate, 9 parts of borax, 4 parts of zinc sulfate, 3 parts of glycinate iron, 3 parts of ammonium molybdate, 3 parts of glycinate copper, 25 parts of liquid ammonia, 25 parts of sulfuric acid, 3 parts of liquid paraffin, and 2 parts of slow-release agent.

[0050] The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following steps:

[0051] a) using 1 / 3 of the total amount of powdered calcium magnesium phosphate fertilizer as both a base fertilizer and a binder, mixed with urea, 1 / 3 of the total amount of potash fertilizer and monoammonium phosphate for preliminary coating to obtain a primary coated granular fertilizer;

[0052] b) uniformly mixing the primary coated granular fertilizer obtained in step a) with borax, zinc sulfate, iron glycinate, ammonium molybdate, copper glycinate, and the remaining potash fertilizer, and then adding the remaining powdered calcium magnesium phosphate fertilizer, liquid ammonia, and sulfuric acid for secondary coating and granulation to achieve multi-layer coating to obtain secondary coated granular fertilizer;

[0053] c) Preparation of sustained-release agent: The raw materials of the sustained-release agent include castor oil, polyoxypropylene triol, polymerized MDI and modified silicon dioxide. Under room temperature, polyoxypropylene triol, castor oil and modified silicon dioxide are stirred and mixed at a mass ratio of 4:1:0.15 at high speed, and then a defoaming agent is added dropwise, and finally stirred and mixed with polymerized MDI to obtain a sustained-release agent.

[0054] Preparation of modified silica: Mix ethanol and distilled water in a volume ratio of 9:1, add a certain amount of γ-aminopropyltriethoxysilane (analytical grade), add ammonia water to adjust the pH to 8-10, add silica at room temperature and continue stirring; then wash with anhydrous ethanol, filter, and dry in an oven to obtain modified silica.

[0055] The secondary coated granular fertilizer obtained in step b) is added to the fluidized bed for preheating, and then all the liquid paraffin is added for lubrication. Finally, the slow-release agent is sprayed into the fluidized bed to react and form a film on the surface of the secondary coated granular fertilizer. The addition is repeated 3 times and the reaction is carried out for a certain period of time to obtain the environmentally friendly slow-release compound fertilizer.

[0056] In order to evaluate the slow-release effect of the environmentally friendly slow-release compound fertilizer, the environmentally friendly slow-release compound fertilizer obtained in Example 3 was taken as an example and compared with traditional fertilizers (such as ordinary urea and uncoated calcium magnesium phosphate fertilizer). In the experiment, all fertilizer samples were tested under the same environmental conditions, and the specific steps were as follows:

[0057] (1) Sample preparation:

[0058] The environmentally friendly slow-release compound fertilizer in Example 3, commercially available common urea, and uncoated calcium magnesium phosphate fertilizer were prepared.

[0059] (2) Sustained release performance test:

[0060] Each fertilizer sample was placed in water under the same conditions, and samples were taken regularly to determine the nitrogen, phosphorus, and potassium content of the aqueous solution.

[0061] (3) Data analysis:

[0062] By comparing the nutrient release of different fertilizers in the same period of time, the slow-release effect can be evaluated. The specific nutrient release rates are shown in the following table:

[0063]

[0064] As can be seen from the table above, this environmentally friendly slow-release compound fertilizer releases slowly in the early stage, maintaining a continuous supply of nutrients and avoiding rapid nutrient loss. Ordinary urea releases up to 50% within 1 day, but quickly reaches 100% in the subsequent period, resulting in nutrient waste. The release rate of uncoated calcium magnesium phosphate fertilizer is between the two, but is still significantly higher than that of environmentally friendly slow-release compound fertilizer.

[0065] The effective release period of environmentally friendly slow-release compound fertilizer can reach 59 days, and the nutrients are released evenly, which is suitable for long-term crop growth. The effective release period of ordinary urea is only 15 days, and the nutrients are released in a short time, which cannot meet the continuous needs of crops. The effective release period of uncoated calcium magnesium phosphate fertilizer is about 30 days, and the release rate is fast, which makes it difficult to guarantee the nutrient needs of crops throughout the growth cycle.

[0066] This environmentally friendly slow-release compound fertilizer can effectively reduce fertilizer loss and reduce environmental pollution. Ordinary urea, due to its rapid release characteristics, is prone to nitrogen loss, leading to eutrophication of water bodies. Uncoated calcium magnesium phosphate fertilizers also have nutrient loss problems, and without special treatment, they are prone to soil and water pollution.

[0067] This environmentally friendly slow-release compound fertilizer has significant advantages in nutrient release rate, effective release period and environmental friendliness. Its slow-release effect can not only meet the growth needs of crops, but also effectively reduce fertilizer waste and environmental pollution, providing an effective solution for sustainable agricultural development.

[0068] The above are only three embodiments of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the principles of the present invention, and these should also be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly slow-release compound fertilizer, comprising the following raw materials in parts by weight: Calcium magnesium phosphate fertilizer 260-340 parts, urea 160-260 parts, potash fertilizer 230-360 parts, monoammonium phosphate 90-130 parts, borax 6-12 parts, zinc sulfate 2-6 parts, glycinate iron 1-5 parts, ammonium molybdate 1-5 parts, glycinate copper 1-5 parts, liquid ammonia 20-30 parts, sulfuric acid 20-30 parts, liquid paraffin 2-3 parts, slow-release agent 1-2 parts; The preparation method of the environmentally friendly slow-release compound fertilizer comprises the following steps: a) using 1 / 3 to 1 / 2 of the total amount of powdered calcium magnesium phosphate fertilizer as both a base fertilizer and a binder, mixed with urea, 1 / 3 to 1 / 2 of the total amount of potash fertilizer and monoammonium phosphate for preliminary coating to obtain a primary coated granular fertilizer; b) uniformly mixing the primary coated granular fertilizer obtained in step a) with borax, zinc sulfate, iron glycinate, ammonium molybdate, copper glycinate, and the remaining potash fertilizer, and then adding the remaining powdered calcium magnesium phosphate fertilizer, liquid ammonia, and sulfuric acid for secondary coating and granulation to achieve multi-layer coating to obtain secondary coated granular fertilizer; c) adding the secondary coated granular fertilizer obtained in step b) into a fluidized bed for preheating, then adding all the liquid paraffin for lubrication, and finally spraying the slow-release agent into the fluidized bed to react and form a film on the surface of the secondary coated granular fertilizer, repeating the addition for 3 times and reacting for a certain period of time to obtain the environmentally friendly slow-release compound fertilizer.

2. The method for preparing the environmentally friendly slow-release compound fertilizer according to claim 1, characterized in that: The raw materials of the sustained-release agent include castor oil, polyoxypropylene triol, polymerized MDI and modified silicon dioxide. Under room temperature, polyoxypropylene triol, castor oil and modified silicon dioxide are stirred and mixed at a mass ratio of 4:1:0.15 at high speed, and then a defoaming agent is added dropwise, and finally stirred and mixed with polymerized MDI to obtain the sustained-release agent.

3. The method for preparing the environmentally friendly slow-release compound fertilizer according to claim 2, characterized in that: The modified silica is prepared by mixing ethanol and distilled water in a volume ratio of 9:1, adding a certain amount of γ-aminopropyltriethoxysilane, dropping ammonia water to adjust the pH to 8-10, adding silica at room temperature and continuing to stir; then washing with anhydrous ethanol, filtering, and drying to obtain the modified silica.

4. The method for preparing the environmentally friendly slow-release compound fertilizer according to claim 1, characterized in that: The potash fertilizer is one or both of potassium sulfate and potassium chloride.

5. An environmentally friendly slow-release compound fertilizer, characterized by: An environmentally friendly slow-release compound fertilizer prepared by the method for preparing the environmentally friendly slow-release compound fertilizer according to any one of claims 1 to 4.

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