JPH0352431B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing liquid fertilizer from a monoammonium phosphate fire extinguishing agent that has lost its function. Conventionally, there are various types of liquid aggregates, but they are manufactured by dissolving ammonium phosphate for fertilizers, urea, potassium chloride, potassium nitrate, etc. in water and using the solution part. It's here. In this case, there are more undissolved parts than expected. It is no exaggeration to say that liquid fertilizer production has been established by using this insoluble portion as a raw material for chemical fertilizer. Therefore, many liquid fertilizer manufacturing plants are attached to chemical fertilizer plants. Most of the insoluble portion is derived from ammonium phosphate for fertilizer. Therefore, in order to reduce the insoluble portion, it has been considered to use highly pure industrial ammonium phosphate, but this is difficult to put into practical use due to the high cost. Furthermore, conventional liquid fertilizers have quality problems. This is because the potassium component is potassium chloride or potassium nitrate, but this has the disadvantage that it leads to excessive application of chlorine and nitric acid when turning liquid fertilizer. One possible solution to this problem is to use potassium sulfate as a raw material, but the solubility of potassium sulfate is low and it is difficult to obtain a practical potassium concentration. Therefore, the use of potassium phosphate can be considered.
There are three types of potassium phosphate: monopotassium phosphate, dibasic potassium phosphate, and tertiary potassium phosphate. Traditionally, potassium phosphate was used as fertilizer, potassium phosphate dibasic, and potassium phosphate tertiary.
Potassium phosphate has not been put to practical use because it is difficult to produce and its high solubility makes it undesirable as a solid fertilizer. The present inventor focused on the fact that dibasic potassium phosphate and tertiary potassium phosphate have high solubility and are not suitable for solid fertilizers. As a result of intensive research into a method for manufacturing inexpensive liquid powder, the present invention was completed. As a result of searching for various inexpensive methods for producing dibasic potassium phosphate and tribasic potassium phosphate, the inventor found that a monoammonium phosphate-based fire extinguishing agent, which is a waste product that has lost its function, is suitable. Ta. Ammonium monophosphate-based fire extinguishing agent (hereinafter simply referred to as waste extinguishing agent), which is a waste product that has lost this function, is normal household industrial waste and is currently being disposed of by offshore machinery or landfill speculation. Therefore, there is concern that it may lead to environmental pollution due to phosphorus. This reuse is also significant in terms of preventing such pollution problems from occurring. Regarding waste fire extinguishing agents, the methods for recovering their components are as follows:
It is known from Special Publication No. 56-23628,
This method aims to recover ammonium monophosphate, which is a component of fire extinguishing agents, and reuse it as a fire extinguishing agent component. This does not imply the use of a unique substance such as liquid fertilizer. In addition, the gist of this method is to separate the moisture-proofing component of the waste fire extinguishing agent and monobasic ammonium phosphate using an ammonia aqueous solution, whereas the present invention uses a urea aqueous solution to separate monobasic ammonium phosphate. The moisture-proofing components are further separated, and monoammonium phosphate is converted into dibasic ammonium phosphate, dibasic potassium phosphate, and tribasic potassium phosphate by adding potassium hydroxide, etc., and dissolved to form a solution. The present invention provides a method for producing fertilizer in a state where The basis of the present invention is the first step of removing the moisture-proofing component of the waste monoammonium phosphate-based fire extinguishing agent with an aqueous urea solution and separating the moisture-proofing component from the monobasic ammonium phosphate. Furthermore, ammonium hydroxide etc. are added to potassium hydroxide to convert monobasic potassium phosphate into substances with high solubility such as dibasic potassium phosphate and tertiary potassium phosphate to obtain a highly concentrated product as a liquid fertilizer. Second process. The third step is to separate the solution portion and the undissolved portion. In order to stabilize the fertilizing effect of liquid fertilizer, the PH of the solution is
The fourth step is to adjust. A fifth step, such as addition of a fertilizer effect enhancer, is further carried out as necessary. Above 5
It is established from the process. The first step is the most important step in the present invention. Although it is a waste fire extinguishing agent, its fire extinguishing function requires excellent fluidity and water repellency, so its main component, ammonium monophosphate, is supplemented with various inorganic salts that have high moisture resistance. Careful moisture-proofing has been applied, including a strict coating with silicone resin.
Therefore, even though the extinguishing agent has lost its function, it cannot be easily dissolved by simply adding water and stirring. However, when an aqueous solution containing several percent of urea is added, the moisture-proofing agent and monobasic ammonium phosphate are separated, and monobasic ammonium phosphate is dissolved in the urea solution. The mechanism behind why urea aqueous solution works in this way is still not clear, but
It is presumed that urea plays some role in causing water to seep into the contact point between the moisture-proofing agent and monoammonium phosphate. Although the concentration of urea necessary for the first step to proceed is a few percent, it is practically necessary to use a much higher concentration of several tens of percent in order to maintain the urea component in the liquid fertilizer. It will be done. Furthermore, in order to accelerate the first step, heating,
Stirring operation is effective. Since urea undergoes an endothermic reaction when dissolved in water, heating is required for practical use. However, since urea tends to deteriorate at relatively low temperatures, it is not preferable to heat it above 60°C. The second step is a step for increasing the solubility of ammonium phosphate. One possible solution is to change monoammonium phosphate to dibasic ammonium phosphate, but the purpose of the present invention includes producing potassium phosphate with less concentration disturbance. To this end, potassium hydroxide is added to convert a portion of primary ammonium phosphate into secondary and tertiary potassium phosphate, and at the same time, secondary ammonium phosphate is produced. However, changing most or all of monoammonium phosphate to potassium phosphate is not preferable because ammonia volatilizes. As mentioned above, one of the purposes of the present invention is to produce potassium phosphate, but one of the important things in producing fertilizer is the three elements of fertilizer: titanium, phosphoric acid, potassium. It is also important to maintain a balance of ingredients. The balance between the three fertilizer elements differs depending on the type of operation, fertilizer application method, etc. Therefore, various brands are required even for liquid fertilizers. Therefore, when it is not desirable to increase the potassium content by adding only potassium, adding ammonia can
We need to maintain that balance. If the second step is performed in an open environment, there is a concern that ammonia will volatilize. Sometimes Cali,
It is effective to use carbonates of ammonia. The amount of ammonia added is suitably within 1 equivalent of monoammonium phosphate, and the amount of potassium added is suitably within 2 equivalents. Heating and stirring are effective in promoting the progress of the second step. However, it is important to maintain the temperature below 60°C to prevent urea from deteriorating. In addition, in order to simplify the process, it is also possible to dissolve potassium hydroxide and potassium carbonate in the urea solution in advance and proceed with the first step and the second step at the same time. The third step is a step of separating the solution from the precipitate in the moisture-proofed portion. The method is
Use of various fibrous filters or solid-liquid separation using a centrifuge are effective. In the fourth step, the first thing that is necessary is to adjust the excess and deficiency of fertilizer components. The next important thing is to adjust the pH of the solution. Conventional methods are sufficiently effective in adjusting the excess and deficiency of fertilizer components. Liquid fertilizers are not only applied to the soil, but are often sprayed directly onto the leaves of plants. The most important things in foliar spraying are to prevent chemical damage and to increase the absorption and utilization rate. For this, the pH of the solution is
was found to be important. For that, the pH of liquid fertilizer
needs to be adjusted to 8.2 or lower. To adjust the pH, inorganic acids such as phosphoric acid, sulfuric acid, and carbonic acid, and organic acids such as acetic acid and citric acid are effective. In the fifth step, depending on the situation in which the liquid fertilizer is used, it is necessary to add materials to enhance the fertilizer effect, and a typical example thereof is a nitrification inhibitor. In order to explain the technical content of the present invention in more detail, Examples and Experimental Examples will be given. However, the present invention is not limited in the slightest by the following examples. Example 1 Add 450 ml of water and 25 g of urea to a 1-volume flask,
This is then treated with waste ammonium monophosphate-based digestive chemicals.
Add 55g, stir at room temperature for about 30 minutes, and then filter using filter paper. Next, 22 g of potassium carbonate was added to adjust the pH to 8.2. As a result of chemical analysis of this filtrate,
It was a liquid fertilizer containing 8% Chituso and 6% phosphoric acid. On the other hand, when the solid matter remaining on the filter paper was dried and its weight was measured, it was 3.7 g. From this, the recovery rate of monoammonium phosphate from waste digestion chemicals was estimated to be over 90%. Example 2 Add 500 g of water to a 1 volume flask equipped with a stirrer.
ml, add 182g of urea, add 160g of waste monoammonium phosphate digestive agent, and boil at room temperature.
After stirring for 30 minutes, 115 g of potassium hydroxide is added, and after stirring again, the mixture is filtered through a glass filter. Chemical analysis of this filtrate revealed that it was a liquid fertilizer containing 10% Chituso and 10% phosphoric acid. Example 3 In a 1-volume flask equipped with a stirrer, add 500 g of water.
ml, add 320g of urea, 115g of potassium hydroxide,
Add waste ammonium monophosphate digestive agent to this.
After adding 160g and stirring at room temperature for about 30 minutes, filter using a glass filter. The filtrate was adjusted to pH 8.2 using a phosphoric acid solution, and chemical analysis revealed that it was 15% Chituso,
It was a liquid fertilizer containing 8% phosphoric acid and 8% potassium. Example 4 Add 500 g of water to a 1 volume flask equipped with a stirrer.
ml, 182 g of urea, and 160 g of waste monoammonium phosphate digestive agent were added, and after stirring at room temperature for about 30 minutes, 120 g of potassium carbonate was added, and after further stirring for 30 minutes, it was filtered using a glass filter. . When the pH of the filtrate was measured, it was 8.2, indicating that there was no need to adjust the pH. Furthermore, as a result of chemical analysis, Chituso
It was a liquid fertilizer containing 14% phosphoric acid and 10% phosphoric acid. Experimental Example 1 The fertilizing effect of the liquid fertilizers obtained in Examples 2 and 3 was examined. The test method is to place soil in a Neubauer pot.
350g of fertilizer was packed, and the test fertilizer and control fertilizer were applied to it at a concentration of 200mg per pot, and the phosphoric acid and potassium components were not corrected. In addition,
As a control fertilizer, a commercially available liquid fertilizer containing 12% Chituso, 8% phosphoric acid, and 6% potassium was used. One day after fertilization, the soil moisture was adjusted to about 60% of the maximum water capacity, and then Komatsuna seeds were sown at a rate of 25 seeds per pot. The germination rate was measured on the 5th day after sowing, and the fresh weight was measured on the 30th day after sowing. The results are shown in Table 1.

[Table] Experimental Example 2 A spreading agent, ethylene glycol, was added at 15% to the liquid fertilizer obtained in Example 3, and the effect of foliar spraying was investigated. The test method is to place soil in a Neubauer pot.
The soil was filled with 350g of water, the soil moisture was adjusted to approximately 60% of the maximum water capacity, and 25 Komatsuna seeds were sown in each pot. No starter fertilizer was applied. After 20 days had passed after sowing, each test fertilizer was applied by foliar spraying. The control fertilizers were commercially available Chitsuso 15%, phosphoric acid 30%,
A foliar spray fertilizer containing 15% potassium was diluted 500 times with water, and the test fertilizer was also diluted with water to have the same concentration of Chituso component. Then, 10 ml per pot was sprayed so that it adhered well to the leaves of Komatsuna. No abnormalities such as concentration disturbances were observed in each section. Table 2 shows the results of measuring the fresh weight of Komatsuna on the 35th day after sowing, that is, on the 15th day after foliar spraying.

【table】

Claims (1)

[Claims] 1. After treating waste ammonium monophosphate fire extinguishing agent with an aqueous solution of urea and removing the generated precipitate by filtration, the obtained filtrate is treated with potassium hydroxide and/or potassium hydroxide. Treatment with an aqueous solution of carbonate converts monoammonium phosphate in the filtrate into dibasic ammonium phosphate and dibasic potassium phosphate or tertiary ammonium phosphate.
A method for producing a liquid fertilizer, characterized by converting it into potassium phosphate. 2 Treating the waste monoammonium phosphate extinguishing agent with a mixed aqueous solution of urea and potassium hydroxide and/or potassium carbonate to convert the monoammonium phosphate in the extinguishing agent into secondary phosphorus. After converting ammonium acid into dibasic potassium phosphate or tertiary potassium phosphate, the precipitate is separated by filtration,
A method for producing a liquid fertilizer, characterized in that the obtained filtrate is used as an active ingredient.