CN106800459A - A kind of urea-formaldehyde fertilizer and urea-formaldehyde compound fertilizer and preparation method thereof - Google Patents

Abstract

The invention discloses a urea-formaldehyde fertilizer and a urea-formaldehyde compound fertilizer and a preparation method thereof. The preparation method of the urea-formaldehyde fertilizer comprises the following steps: 1) mixing starch with water, and gelatinizing to obtain starch paste; 2) mixing the starch paste with urea and formaldehyde, then adding plant ash, and reacting to obtain solution I; 3) mixing The solution I is mixed with an adsorbent, and waste liquid from a monosodium glutamate enterprise is added at the same time, mixed to obtain a urea-formaldehyde fertilizer slurry, and solidified to obtain a urea-formaldehyde fertilizer. Alkaline industrial waste (plant ash) and acidic industrial waste (monosodium glutamate gas-liquid waste liquid) used in the present invention are all through concentrated treatment, and guarantee that its heavy metal element content does not exceed national standard, avoids causing secondary pollution, with Utilize the acidity and alkalinity of industrial waste and the fertilizer nutrients contained therein. The fertilizer of the present invention can be fertilized once in planting practice without burning seedlings, conforming to the nutrient absorption law of crops, thereby reducing the loss of fertilizer, increasing the utilization rate of fertilizer, and reducing the amount of fertilizer.

Description

A kind of urea-formaldehyde fertilizer and urea-formaldehyde compound fertilizer and preparation method thereof

technical field

The invention relates to a urea-formaldehyde fertilizer, a urea-formaldehyde compound fertilizer and a preparation method thereof, belonging to the technical field of fertilizers.

Background technique

Many industrial enterprises have by-products, yet one enterprise's waste can be a valuable resource in another. If we can recycle the discharge of enterprises, we can not only reduce the environmental pressure of the three wastes treatment, but also save production costs.

In patent ZL 200810225221.3, a urea-formaldehyde fertilizer and urea-formaldehyde compound fertilizer and its preparation method are disclosed. In the reaction process of urea-formaldehyde fertilizer preparation, in order to further improve the availability of nutrients in the fertilizer, organic and inorganic adsorbents are also added.

Plant ash is the residual ash after burning plants. It contains potassium, calcium, phosphorus, silicon, sulfur, magnesium, boron, zinc and other nutrients, among which potassium, calcium and phosphorus are more abundant, and generally contain potassium (K ₂ O) 5-12%, calcium (CaO) 5-20%, phosphorus (P ₂ O ₅ ) 0.5-3.5%. The nutrient elements in the plant ash come from the crops and are applied to the crops. They can be used directly without purification and separation, and the cost is low and the effect is good. At the same time, some plant ash also contains ash and a large amount of incompletely oxidized carbon. However, because the plant ash directly There are certain limitations for making common fertilizers. It is understood that my country's annual output of crop straw alone is about 700 million tons. Straw power generation, which came into being as the times require, is a new industry that has just started in the past one or two years. It has developed rapidly, and at the same time it produces a large amount of plant ash waste.

Contents of the invention

The object of the present invention is to provide a kind of urea-formaldehyde fertilizer and urea-formaldehyde compound fertilizer and preparation method thereof, the present invention utilizes industrial waste to be used for preparing urea-formaldehyde fertilizer and urea-formaldehyde compound fertilizer, not only directly utilizes industrial waste, has reduced reaction cost, and has increased fertilizer in active ingredients.

The preparation method of urea-formaldehyde fertilizer provided by the invention comprises the steps:

1) mixing starch with water and gelatinizing to obtain starch paste;

2) Mix the starch paste with urea and formaldehyde, then add plant ash, and react to obtain solution I;

3) Mix the solution I with the adsorbent, and add waste liquid from monosodium glutamate enterprises at the same time, mix to obtain urea-formaldehyde fertilizer slurry, and solidify to obtain urea-formaldehyde fertilizer.

The invention utilizes the alkalinity of plant ash and the acidity of monosodium glutamate enterprise waste liquid to prepare urea-formaldehyde fertilizer.

In the above preparation method, in step (1), the mass ratio of the starch to the water may be 1:5-20, specifically 1:5, 1:10, 1:20, 1:5-10 , 1:10~20 or 1:5~10;

The starch can be various non-corruptible and cheap starches such as wheat flour, corn flour, sweet potato flour or dust collected from flour mills.

In the above preparation method, in step (2), the molar ratio of the urea to the formaldehyde may be 2-4:1, specifically 2:1, 2.45:1, 4:1, 2-2.45:1 or 2.45～4:1;

The mass ratio of the urea, the plant ash and the starch may be 30-60:20-1:1, specifically 30:5:1 or 45:3:1.

In the above preparation method, in step (2), the temperature of the reaction is 30-90°C, specifically 65°C, 70°C, 80°C, and the time is 30-120min, specifically 30min, 60min, 120min, 30-60min, 60-120min or 30-100min.

In the above preparation method, in step (3), the mass ratio of the urea to the adsorbent may be 2-50:1, specifically 2-10:1, 2:1, 3:1 or 10: 1;

In step (3), when the urea-formaldehyde fertilizer slurry is solidified, stop adding the waste liquid from the monosodium glutamate enterprise. Usually, the mass ratio of the waste liquid from the monosodium glutamate enterprise to the adsorbent can be 1:0.06-2.

The adsorbent can be non-metallic mineral powder and/or organic powder;

The non-metallic mineral powder can be at least one of zeolite, bentonite, diatomite and attapulgite;

The organic powder can be at least one of straw, sawdust and peat.

In the above-mentioned preparation method, step 3) also includes the step of granulating when the mass moisture content of the urea-formaldehyde fertilizer slurry can be 5-40%, specifically 5%, 30%, 40%, 5-40%. 30%, 30-40% or 5-35%; when the solution I begins to solidify, stop adding the waste liquid from the monosodium glutamate enterprise.

The granulation method can be direct crushing granulation, extrusion granulation or direct extrusion molding method. The method of direct chopping and granulation is to cut the urea-formaldehyde fertilizer slurry or the urea-formaldehyde compound fertilizer slurry into particles of different particle sizes; the method of extrusion granulation is to use an extrusion granulator to perform granulation. Both direct chopping and granulation methods and extrusion granulation methods can obtain products with different particle sizes, such as <1mm, 1-2mm, 2-4mm, 4-8mm or >8mm. The extrusion granulation method can also obtain products of different shapes, such as short columns, long strips, and rods, which can be selected according to actual needs. The degree can be adjusted arbitrarily, such as 1mm, 2mm, 8mm or 20mm. The method of mold direct extrusion molding can choose the shape and size of the mold arbitrarily according to the needs of use.

The present invention also provides the urea-formaldehyde fertilizer prepared by the above preparation method, the pH value of the urea-formaldehyde fertilizer is 6.8-7, and the mass percentage of hot water insoluble nitrogen is less than or equal to 8%.

The present invention further provides a urea-formaldehyde compound fertilizer with a pH value of 6.8-7, wherein the mass percentage of hot water insoluble nitrogen is less than or equal to 8%.

The preparation method of the urea-formaldehyde compound fertilizer is basically the same as the preparation method of the urea-formaldehyde fertilizer, except that in step 3), the following steps are continued after mixing the solution I, the adsorbent and other fertilizers;

The mass ratio of the urea to the other fertilizers is 3-40:1.

The other fertilizers can be at least one of phosphorus and potassium fertilizers, organic fertilizers and medium and trace element fertilizers.

The phosphorus and potassium fertilizer can be at least one of phosphate rock powder, superphosphate, monoammonium phosphate, diammonium phosphate, potassium chloride, potassium sulfate, potassium carbonate, potassium magnesium fertilizer and potassium calcium fertilizer. It can be at least one of calcium carbonate, magnesium sulfate, manganese sulfate, manganese chloride, boric acid, borax, zinc sulfate, zinc chloride, ammonium molybdate and ferrous sulfate.

Alkaline industrial waste (plant ash) and acidic industrial waste (monosodium glutamate gas-liquid waste liquid) used in the present invention are all through concentrated treatment, and guarantee that its heavy metal element content does not exceed national standard, avoids causing secondary pollution, with Utilize the acidity and alkalinity of industrial waste and the fertilizer nutrients contained therein.

The present invention has the following advantages:

1. The invention of this method utilizes industrial waste to prepare, so that industrial waste can be reused, and can effectively solve the environmental pollution caused by industrial waste.

2. The invention can reduce the preparation cost, and the cost of the industrial waste used is low, and the industrial waste can be turned into treasure.

3. The pH value of the fertilizer in the present invention is between 6.8 and 7, which is suitable for the use of most crops and is suitable for popularization.

4, the content of the hot water insoluble nitrogen in urea-formaldehyde fertilizer of the present invention and urea-formaldehyde compound fertilizer reduces greatly (only accounts for 1～8% of fertilizer quality), and the AI value of fertilizer > 50%, has improved the quality of fertilizer, thereby improves the quality of fertilizer. Nitrogen use efficiency increases the effectiveness of fertilizers.

5. The adsorbent added in the present invention has adsorbed the free unreacted available nitrogen (urea) in the fertilizer to the greatest extent, so that its release is slowed down, and at the same time, in the process of fertilizer decomposition, the quick-acting nitrogen (urea) formed by decomposition is also decomposed by adsorption. The release of nitrogen (such as NH ₄ ⁺ -N) is delayed. Adsorbent, plant ash, organic components in monosodium glutamate enterprise waste liquid and urea-formaldehyde fertilizer jointly constitute a biodegradable matrix system (Biodegradable Matrix system). Urea-formaldehyde slow-release fertilizer and remaining unreacted free nitrogen (urea) are dispersed in it, so that The slow release of fertilizer is enhanced, as shown in Figure 1.

6. The granulation process in the present invention strengthens the compactness of the fertilizer. Since urea-formaldehyde fertilizer itself needs to be degraded before it can be absorbed by plants, and its water solubility is low, the outer layer of fertilizer with a certain particle size and additives have a certain barrier effect on the release of internal fertilizer nutrients. The particle size of fertilizer particles and Compactness can affect the slow release of fertilizers. Experiments show that the slow-release performance of the fertilizer obtained by the present invention is obviously higher than that of ordinary urea, and the fertilizer with larger particles, tighter and larger AI value has stronger slow-release performance; the fertilizer of the present invention can be used once in planting practice. Fertilization does not burn seedlings, and ordinary urea will inhibit the growth of crops under the condition of equal nitrogen content, and due to the slow release of fertilizers, it conforms to the law of crop nutrient absorption, thus reducing the loss of fertilizers, increasing the utilization rate of fertilizers, and reducing the amount of fertilizers.

Description of drawings

Figure 1 is a schematic cross-sectional view of the degradable matrix controlled release system.

Figure 2 is the leaching curves of urea-formaldehyde fertilizers with different particle sizes prepared in Example 1 of the present invention.

detailed description

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

In the following examples, plant ash contains (K ₂ O) 11%, calcium (CaO) 15%, phosphorus (P ₂ O ₅ ) 2.7%, mass fraction, and contains total sugar 42% in monosodium glutamate enterprise waste liquid, mass fraction, pH2.8.

Embodiment 1, preparation and detection of urea-formaldehyde fertilizer

1. Preparation

1) Add 400g corn flour and 4kg water into a beaker (mass ratio of corn flour to water is 1:10), heat to boiling, keep warm for 15min, gelatinize to form starch paste, transfer all starch paste into the reaction kettle.

2) Add 18kg of urea and 10 liters of 37% formaldehyde to the reactor, the molar ratio of urea to formaldehyde is 2.45:1, and the mass ratio of urea to corn flour is 45:1; quickly, add 1kg of plant ash. Then the temperature was raised to 70°C and kept for 60 minutes to obtain solution Ⅰ.

3) Put 6kg of non-metallic mineral powder (the mass ratio of non-metallic mineral powder to urea is 1:3) into another empty container, then add solution I into this container, and add waste liquid from monosodium glutamate enterprises at the same time, while adding While stirring the industrial wastewater from the monosodium glutamate factory, stop adding 1kg of waste liquid from the monosodium glutamate enterprise when the solution I starts to solidify, so that the non-metallic mineral powder adsorbent is evenly distributed in it, and the urea-formaldehyde fertilizer slurry is obtained. Continue to stir, and the viscosity of the urea-formaldehyde fertilizer slurry The viscosity gradually increases and gradually solidifies. The viscosity of the slurry itself can keep the added non-metallic mineral powder adsorbent evenly distributed therein, and the obtained urea-formaldehyde fertilizer slurry has a Metrix system structure and a degradation system structure.

Among them, the non-metallic mineral powder is a mixture of zeolite, bentonite, diatomite and attapulgite, and the diameter of each mineral powder is 150 mesh; the mass ratio of zeolite, bentonite, diatomite and attapulgite is 1:1:1 :1.

4) Granulation

When the water content of the urea-formaldehyde fertilizer slurry in step 3) is 30% (i.e., the slurry is solidified to have plasticity but not fully solidified), the slurry is processed and granulated, respectively, according to the following three methods:

(1) Direct crushing and granulation: chop the above-mentioned plastic fertilizer slurry, then sieve it, and divide it into fertilizer particles of <1mm, 1-2mm, and 2-4mm according to the particle size. The part >4mm is further chopped until all pass through a 4mm mesh sieve; the compactness of the product obtained by this method is relatively small.

(2) Extrusion granulation: Use a roller-flat mode extrusion granulator to make granules with diameters of 1mm, 2mm, and 4mm respectively by changing the size of the sieve holes on the template.

(3) Extrusion granulation: Use a screw extrusion granulator to make 1mm, 2mm, and 4mm diameter granules by changing the size of the sieve holes on the template.

The granules produced by the above granulation methods are shaped by a disc granulator or a drum granulator. The above operations are usually carried out when the water content of the fertilizer is 30%, and the granulated products are dried naturally or directly. , to obtain urea-formaldehyde fertilizer.

The method of direct chopping adopts chopping the raw material with plasticity into particles of a certain size, and the compactness of the product prepared by this method is small. Extrusion granulation or extrusion granulation in a mold, due to the different extrusion forces applied, the compactness of the product is also different, but the compactness is higher than that of the product obtained by the direct chopping method. big. Due to the different feeding system, the products using the screw extrusion granulator have greater compactness than those obtained by the roller-flat extrusion granulator.

The pH value of the urea-formaldehyde fertilizer slurry during granulation and the pH value of the urea-formaldehyde fertilizer after granulation are both 7.

2. Effect detection

(1) Detection of nitrogen content and effectiveness of urea-formaldehyde fertilizer

Dry and pulverize the urea-formaldehyde fertilizers of different particle types prepared according to the method described in step 1, and pass through a 0.25mm sieve.

The total nitrogen content of fertilizers was determined by the Kjeldahl method.

Determination of cold water insoluble nitrogen in fertilizers: Weigh 1.000g of fertilizer samples passing through a 0.5mm sieve into a 100ml beaker, moisten with a small amount of ethanol, add 20ml (25±2°C) of water, stir for 15 seconds every minute, after 15 minutes , The clarified liquid is filtered with fast filter paper, and then the insoluble matter is washed with water at the same temperature for 4-5 times, then all the insoluble matter is transferred to the filter paper, and then continue to wash fully to make the filtrate reach 250ml. Use the Kjeldahl method to measure the nitrogen content of the remaining fertilizer on the filter paper, which is the cold water insoluble nitrogen content.

Determination of hot water insoluble nitrogen in fertilizers: Weigh 1.000g of fertilizer samples that pass through a 0.5mm sieve into a 250ml beaker, moisten with a small amount of ethanol, add 100ml of boiling 0.063M phosphate buffer solution, stir, cover with a watch glass, and put in a boiling In a water bath (the liquid surface in the beaker is completely immersed in boiling water), stir gently for 15 seconds every 10 minutes. After 30 minutes, filter with fast filter paper, and place the remaining solution in the boiling water bath in the filter gap. Finally, transfer all the insoluble matter to the filter paper, and then continue to wash with boiling buffer solution to make the filtrate reach 250ml. The content of hot water insoluble nitrogen on the filter paper was determined by the Kjeldahl method.

The calculation formula of fertilizer AI value is as follows: AI value = (cold water insoluble nitrogen content - hot water insoluble nitrogen content) × 100%/cold water insoluble nitrogen content.

The experiment is set to repeat 3 times, and the results show that the total nitrogen content of the urea-formaldehyde fertilizer prepared by the method is an average of 32.66%, the average content (%) of cold water insoluble nitrogen is 12.69%, and the average content (%) of hot water insoluble nitrogen is 4.67%, and the average AI value is 64%, indicating that the effectiveness of the urea-formaldehyde fertilizer of the present invention is high.

(2) Determination of nutrient release rate of urea-formaldehyde fertilizers with different particle sizes

The 1-2mm fertilizer sample made after direct crushing of the urea-formaldehyde fertilizer obtained in step 1 and the fertilizer sample with a diameter of 4mm made by a screw extruder granulator are used as experimental materials, and urea is used as a contrast; In the experimental methods, except for the different fertilizers used, the rest are the same.

Soil loading column: Take 16 plastic tubes with a diameter of 5 cm and a height of 35 cm, first seal the bottom of the plastic tube with gauze, and then add the following substances to it in turn: first put 40 g of sand into it, and then pack it according to a certain degree of firmness Put 500g of air-dried soil through a 2mm sieve, then sprinkle 0.5gN fertilizer samples on top, then fill it with 100g of air-dried soil through a 2mm sieve according to the same compactness, and finally add 40g of sand. Each fertilizer was repeated four times, and a blank control was made at the same time.

Leaching: The first leaching: first add 150ml of water to saturate the water in the soil column. After 2 hours, when the water has penetrated, add 100ml of water to the leaching soil column at one time, and seal it with Para film after leaching is complete. Put the soil column into a 25°C incubator, take out the soil column every 3 days, add 100ml of water into the leached soil column at one time, seal the soil column with Para film after leaching is complete, and continue to cultivate.

Preparation of the elution curve: Measure the increase of total nitrogen in the eluate of each soil column with fertilizer compared with the blank treatment as the vertical axis and time as the horizontal axis, and make the fertilizer leaching curve.

The results are shown in Figure 2. The results show that about 80% of the nutrients in urea are washed out after the first two washings; urea-formaldehyde with a diameter of 1-2 mm and a relatively loose texture is produced by direct crushing and granulation The leaching amount of the fertilizer in the early stage is also relatively large, but it is still much smaller than the leaching amount of urea; the leaching rate of urea-formaldehyde fertilizer with a diameter of 4mm produced by extrusion granulation is obviously slow, and the leaching curve is almost linear, which means It is because the fertilizer granules produced by extrusion granulation are relatively compact, the particle size of the fertilizer is large, and the barrier effect of the insoluble part is more obvious, so that the available nitrogen in it cannot be released quickly, but with the fertilizer Slow decomposition and gradual release.

This experiment also shows that when the composition of the fertilizer is the same, its structure, diameter and compactness cause different nutrient release rates of the fertilizer.

Embodiment 2, preparation and detection of urea-formaldehyde fertilizer

1. Preparation

1. Add 500g of sweet potato flour and 2.5kg of water into a beaker (mass ratio of sweet potato flour to water is 1:5), heat to boiling, keep warm for 15min, gelatinize to form starch paste, transfer all the starch paste into the reaction kettle.

2. Add 15kg of urea and 10 liters of 37% formaldehyde to the reaction kettle. The molar ratio of urea to formaldehyde is 2:1, and the mass ratio of urea to sweet potato flour is 30:1; quickly add 0.5kg of plant ash, and then heat up to 65 ℃, keep warm for 30min, and react to obtain solution Ⅰ.

3. Put 7.5kg of non-metallic mineral powder (mass ratio of non-metallic mineral powder to urea is 1:2) into another empty container, then add solution I into the container, and add industrial waste water from monosodium glutamate factory at the same time, Stir while adding, stop adding the industrial waste water from the monosodium glutamate plant when the solution I begins to solidify, stir to make the non-metallic mineral powder adsorbent evenly distributed therein, obtain the urea-formaldehyde fertilizer slurry, continue to stir, the viscosity of the urea-formaldehyde fertilizer slurry increases gradually, Gradually solidified, the viscosity of the slurry itself can keep the non-metallic mineral powder adsorbent evenly distributed in it, and the obtained urea-formaldehyde fertilizer slurry has a Metrix system structure and a degradation system structure, as shown in Figure 1.

Among them, the non-metallic mineral powder adsorbent is a mixture of zeolite, bentonite, diatomite and attapulgite, and the diameter of each mineral powder is 60 mesh; the mass ratio of zeolite, bentonite, diatomite and attapulgite is 1:1 :1:1.

4. Granulation

When the water content of the above-mentioned urea-formaldehyde fertilizer slurry is 5% (that is, before the slurry is solidified to have plasticity but not completely solidified), the slurry is processed and granulated, and the granulation method is the same as step 1 in Example 1.

The pH value of the urea-formaldehyde fertilizer slurry during granulation and the pH value of the urea-formaldehyde fertilizer after granulation are both 7.

2. Effect detection

(1) Detection of nitrogen content and effectiveness of urea-formaldehyde fertilizer

Dry and pulverize the urea-formaldehyde fertilizer prepared by the method described in step one, and pass through a 0.25mm sieve. Then detect the total nitrogen content, the content of cold water insoluble nitrogen and the content of hot water insoluble nitrogen in the fertilizer according to the method described in step 2 of Example 1, and calculate the AI value of the urea-formaldehyde fertilizer.

The experiment is set to repeat 3 times, and the results are as follows: the total nitrogen content of the urea-formaldehyde fertilizer prepared by the method described in this example is an average of 31%, the content (%) of cold water insoluble nitrogen is an average of 23%, and the content of hot water insoluble nitrogen (%) is 8% on average, and the AI value is 65% on average, showing that the effectiveness of the urea-formaldehyde fertilizer of the present invention is high.

(2) Determination of nutrient release rate of urea-formaldehyde fertilizers with different particle sizes

Determination was carried out according to the method described in step 2 in Example 1.

The experiment was repeated 3 times. The results show that under the same composition conditions, the leaching rate of the urea-formaldehyde fertilizer with a diameter of 4mm produced by the extrusion granulation method of the present invention is very slow, and the elution curve is almost linear, and the direct crushing and granulation method of the present invention The leaching rate of the urea-formaldehyde fertilizer with a diameter of 1 to 2 mm and loose texture is also relatively large in the early stage, but it is much smaller than the leaching rate of urea; it shows that the urea-formaldehyde fertilizer of the present invention has obvious slow release sex.

Embodiment 3, preparation and detection of urea-formaldehyde fertilizer

1. Preparation

1. Add 200g of wheat flour and 4kg of water into a beaker (mass ratio of wheat flour to water is 1:20), heat to boiling, keep warm for 15min, gelatinize to form starch paste, transfer all the starch paste into the reaction kettle.

2. Then add 9kg of urea and 3 liters of 37% formaldehyde to the reactor, the molar ratio of urea to formaldehyde is 4:1, and the mass ratio of urea to wheat flour is 45:1; quickly add 2kg of plant ash to adjust the reaction system in the reactor When the pH value reached 13, the temperature was raised to 80°C and kept for 120 minutes to obtain solution Ⅰ.

3. Put 0.9kg of non-metallic mineral powder (the mass ratio of non-metallic mineral powder to urea is 1:10) into another empty container, then add solution I into the beaker, and add the industrial waste water from the monosodium glutamate factory at the same time, while adding While stirring, stop adding the industrial waste water from the monosodium glutamate plant when the solution I starts to solidify, stir to make the non-metallic mineral powder adsorbent evenly distributed in it, and obtain the urea-formaldehyde fertilizer slurry, continue to stir, the viscosity of the urea-formaldehyde fertilizer slurry increases gradually, gradually After solidification, the viscosity of the slurry itself can keep the added non-metallic mineral powder adsorbent evenly distributed in it, and the obtained urea-formaldehyde fertilizer slurry has a Metrix system structure and a degradation system structure, as shown in Figure 1.

Among them, the non-metallic mineral powder adsorbent is a mixture of zeolite, bentonite, diatomite and attapulgite, and the diameter of each mineral powder is 2000 mesh; the mass ratio of zeolite, bentonite, diatomite and attapulgite is 1:1 :1:1.

4. Granulation

When the water content of the above-mentioned urea-formaldehyde fertilizer slurry is 40% (that is, before the slurry is solidified to have plasticity but not completely solidified), the slurry is processed and granulated, and the granulation method is as described in step one in Example 1.

The pH value of the urea-formaldehyde fertilizer slurry during granulation and the pH value of the urea-formaldehyde fertilizer after granulation are both 7.

2. Effect detection

(1) Detection of nitrogen content and effectiveness of urea-formaldehyde fertilizer

The fertilizer prepared by the method described in step 1 is dried, crushed, and passed through a 0.25 mm sieve. Then, detect the total nitrogen content, cold water insoluble nitrogen content and hot water insoluble nitrogen content in the fertilizer according to the method described in step 2 of Example 1, and calculate the AI value of the fertilizer.

The experiment is set to repeat 3 times, and the results show that the total nitrogen content of the urea-formaldehyde fertilizer prepared by the method described in this example is an average of 40%, the content (%) of cold water insoluble nitrogen is an average of 5%, and the content of hot water insoluble nitrogen (%) was 2% on average, and the AI value was 60% on average, indicating that the fertilizer of the present invention has high effectiveness.

(2) Determination of nutrient release rate of urea-formaldehyde fertilizers with different particle sizes

Determination was carried out according to the method described in step 2 in Example 1.

The experiment was repeated 3 times. The results show that under the same composition conditions, the leaching rate of the urea-formaldehyde fertilizer with a diameter of 4mm produced by the extrusion granulation method of the present invention is very slow, and the elution curve is almost linear, and the direct crushing and granulation method of the present invention The leaching rate of the obtained diameter 1-2mm, loose texture urea-formaldehyde fertilizer is also relatively large in the early stage leaching out amount, but all is much smaller than the leaching rate of urea; Show that urea-formaldehyde fertilizer of the present invention has obvious slow release sex.

Embodiment 4, the preparation of urea-formaldehyde compound fertilizer

The preparation method is the same as the preparation one in Example 1, except that the mass ratio of adding non-metallic minerals (zeolite, bentonite, diatomite and attapulgite mixture is 1:1:1:1, the diameter of each mineral powder 2000 mesh) while adding 3kg of organic matter fine powder and 3kg of decomposed pig manure that was dried and pulverized, the used organic matter fine powder adsorbent and the organic fertilizer that was decomposed and dried and pulverized all passed through a 2mm sieve, and the mass ratio of the two was 1 :1. After the fertilizer is solidified, it is granulated by extrusion granulation to obtain urea-formaldehyde compound fertilizer.

The prepared urea-formaldehyde compound fertilizer has been proved by the rape pot test that it has a long fertilizer effect period and sufficient nutrient supply compared with ordinary organic fertilizers, and one-time fertilization can meet the needs of crops throughout the growth period.

Claims (10)

1. a preparation method of urea-formaldehyde fertilizer, comprising the steps of: 1) mixing starch with water and gelatinizing to obtain starch paste; 2) Mix the starch paste with urea and formaldehyde, then add plant ash, and react to obtain solution I; 3) Mix the solution I with the adsorbent, and add waste liquid from monosodium glutamate enterprises at the same time, mix to obtain urea-formaldehyde fertilizer slurry, and solidify to obtain urea-formaldehyde fertilizer. 2. a preparation method of urea-formaldehyde compound fertilizer, comprises the steps: 1) mixing starch with water and gelatinizing to obtain starch paste; 2) Mix the starch paste with urea and formaldehyde, then add plant ash, and react to obtain solution I; 3) Mix the solution I, the adsorbent and other fertilizers, and add waste liquid from monosodium glutamate enterprises at the same time, mix to obtain urea-formaldehyde compound fertilizer slurry, and solidify to obtain urea-formaldehyde compound fertilizer; The other fertilizers are at least one of phosphorus and potassium fertilizers, organic fertilizers and medium and trace element fertilizers. 3. The preparation method according to claim 1 or 2, characterized in that in step (1), the mass ratio of the starch to the water is 1:5-20. 4. The preparation method according to any one of claims 1-3, characterized in that: in step (2), the molar ratio of the urea to the formaldehyde is 2 to 4:1, The mass ratio of the urea, the plant ash and the starch is 30-60:20-1:1. 5. The preparation method according to any one of claims 1-4, characterized in that: in step (2), the reaction temperature is 30-90° C., and the reaction time is 30-120 min. 6. The preparation method according to any one of claims 1-4, characterized in that: in step (3), the mass ratio of the urea to the adsorbent is 2 to 50:1; The mass ratio of the urea to the other fertilizers is 3-40:1. 7. The preparation method according to any one of claims 1-6, characterized in that: in step (3), the adsorbent is non-metallic mineral powder and/or organic powder; The non-metallic mineral powder is at least one of zeolite, bentonite, diatomite and attapulgite; The organic powder is at least one of straw, sawdust and peat. 8. according to the preparation method described in any one in claim 1-7, it is characterized in that: in step (3), in step 3), also comprise that the mass moisture content of described urea-formaldehyde fertilizer slurry is 5～40% Carry out the step of granulation; When the solution I started to solidify, stop adding the waste liquid from the monosodium glutamate enterprise. 9. The urea-formaldehyde fertilizer prepared by the method described in any one of claim 1 or 3-8. 10. the urea-formaldehyde compound fertilizer prepared by the method described in any one of claim 2 or 3-8.