JPH0351672B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Purpose of the invention (industrial application field) This invention provides a method for easily producing fertilizer with a formulation suitable for agricultural soil crops, supplying it at low cost,
This invention relates to a method for producing granular light-burned magnesium that is easy to blend with powdered light-burnt magnesium and has excellent disintegrability, which is used in the bulk blend fertilizer method aimed at saving labor for farmers. (Problems to be solved by conventional technology and the invention) Lightly calcined magnesium (MgO) is manufactured using magnesite ore (MgCO ₃ ) calcined at 500 to 900℃, seawater magnesia, brucite, etc. as main raw materials. be done. Although the properties of the light calcined magnesium vary depending on the firing method, thermally decomposed activated magnesia is particularly characterized by magnesium hydroxychloride (setting action, hardening properties).
It is known that it is used as magnesia cement by taking advantage of its coagulation effect and reacting MgO, MgCl ₂ and H ₂ O (Gypsum Lime Handbook edited by the Gypsum and Lime Society). And, lightly calcined magnesium
It is already known that being a highly basic substance with a pH of about 13 promotes the above reaction (hydration reaction) with water and causes coagulation. Sarpomagnesium is used as a magnesium soil raw material for agricultural bulk blend fertilizers, but it contains potassium in addition to magnesium soil as an ingredient, and is not suitable for fertilizers that do not require potassium components. A formulation of lightly calcined magnesium with only However, since it is used in the form of light calcined magnesium powder, and the other raw materials are granular, it causes segregation during mixing, and a uniform blend cannot be achieved, so a countermeasure has been sought. Moreover, in order to supply it as a raw material fertilizer in a bulk blend system, it must be in a granular form with high hardness and excellent disintegration in the soil, and methods for granulating it have been studied. Methods include mixing soluble homogeneous raw materials (e.g. magnesium sulfate, magnesium hydroxide) and pressurizing it to form pressure pieces, adding a granulating agent containing organic matter to granulate it, and granulating it by adding a granulating agent containing organic matter. Methods such as adding inorganic powder to granulate (Japanese Patent Application Laid-Open No. 54-97263) have been proposed, but in order to improve storage stability and handling, all methods except the pressure plate method require increasing the hardness of the soil. The granulation of light-fired magnesium was not permitted under the Fertilizer Control Law until 1985, as no suitable method had been found for it, but from 1981, the appropriate method was introduced. It became recognized with the advent of Here, the magnesia fertilizer is classified according to the Fertilizer Control Law and prescribed by official standards, and includes, for example, lightly burnt magnesium, magnesium hydroxide, magnesium sulfate, and the like. However, when lightly calcined magnesium is granulated with a hygroscopic granulating agent, it reacts with water, hardens and coagulates, and in this case it does not disintegrate in the soil and does not serve as a fertilizer. (2) Structure of the invention (Means and effects for solving the problems) The present invention was developed in view of the above circumstances, and has high hardness, easily disintegrates in water and soil, and has no fertilizer effect. The object of the present invention is to provide a method for producing collapsible granular lightly calcined magnesium that can exhibit the following properties. In the present invention, a granulating agent such as a lignin sulfonate solution is added to light calcined magnesium, and limestone powder, lime cake, hydrotalc, etc. are mixed as necessary, and then the mixture is granulated and then dried. This is achieved by doing. The above mixing is preferably carried out by kneading under high pressure using a kneader depending on the amounts of the dispersant and granulating agent. The purpose of kneading is to create a dispersant,
The purpose is to uniformly mix the granulating agent between the lightly calcined magnesium powder. Further, the granulation molding may be simply rolling granulation or extrusion molding, or may even be a step of performing rolling granulation after extrusion molding. The lignin sulfonate solution of the granulating agent used in the present invention is obtained from a paper mill;
There are three types of salts: salts with calcium substitution, magnesium substitution, and sodium substitution; however, salts with calcium substitution have a very high pH of 12 to 13, so they tend to solidify due to hydration reaction, and are lightly sintered. Test results for magnesium granulation showed that it became hydrated and did not disintegrate in the soil after being left for 24 hours, making it unsuitable.Sodium-substituted product and then magnesium-substituted product were suitable.
The characteristics of such sodium-substituted or magnesium-substituted nignine sulfonate solutions include the pH
Since the value is as low as 3.5 to 4.5 and there is no hydration reaction, it does not absorb moisture in the air during the storage period after granulation, and it is possible to obtain stable granulated products without reacting with the moisture in the air. can. In addition, the molecular weight of the sodium-substituted or magnesium-substituted products is in the small range of several thousand, whereas the molecular weight of the calcium-substituted products is in the small range of several thousand.
It is a large unit of tens of thousands. Therefore, in the above-mentioned sodium-substituted or magnesium-substituted products, a large amount of lignin enters between the molecules of lightly calcined magnesium, thereby preventing molecular coagulation.
It maintains its disintegrability. In addition, as dispersants, we use limestone powder, lime cake (sugar manufacturing byproduct lime), brucite powder (hydralcum powder), etc., which are compatible with the basicity of light calcined magnesium and easily disperse in water. The purpose is to prevent the light-sintered magnesium powder particles from solidifying and aggregating with each other. Therefore, other materials can be used as long as they are non-hygroscopic ore powders that are compatible with basicity. Thus, the collapsible granular lightly calcined magnesium obtained by the present invention does not change in quality due to moisture absorption even when left in the air for a long time during storage, and is stable in moisture absorption experiments.When used, it is stable even in water and soil. It has excellent disintegration properties and is sufficiently effective as a fertilizer. (Examples) Some examples of the present invention will be shown below.
The limestone powder used as a dispersing agent is made by crushing normally produced limestone into about 100 to 200 mesh pieces.The lime cake (lime by-product of sugar manufacturing) is used after completely removing moisture, and the hydrotalc powder is Hydrotalc stone crushed to about 100 to 200 mesh pieces was used. In addition, the lignin sulfonate solution used as a granulating agent is concentrated to a moisture content of 40 to 50% at a paper mill, and the ingredients shown in Table 1 are diluted three times with water. did. Example 1 0.73 kg of limestone powder was added to 7.44 kg of lightly calcined magnesium and mixed in a kneader. Add 1.83 kg of sodium-based lignin sulfonate solution to the mixed light calcined magnesium containing limestone powder, and further mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. When the sized sample was dried using a hot air dryer, granular light burnt magnesium was obtained, and this sample was used as prototype 1 for testing. Example 2 2.19 kg of hydrotalc powder was added to 5.98 kg of lightly calcined magnesium and mixed in a kneader. Add 1.83 kg of sodium-based lignin sulfonate solution to the mixed light calcined magnesium containing hydrotalcite powder, and further mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. When the sized sample was dried using a hot air dryer, granular light burnt magnesium was obtained, and this sample was used as prototype 2 for testing. Example 3 Lightly baked magnesium 7.26Kg and lime cake 0.95Kg
and mix using a kneader. Add 1.79 kg of sodium-based lignin sulfonate solution to the mixed light baked magnesium with lime cake, and mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. When the sized sample was dried using a hot air dryer, granular light burnt magnesium was obtained, and this sample was used as prototype 3 for testing. Example 4 0.73 kg of limestone powder was added to 7.44 kg of lightly calcined magnesium and mixed in a kneader. Add 1.83 kg of magnesium-based lignin sulfonate solution to the mixed light calcined magnesium containing limestone powder, and further mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. When the sized sample was dried using a hot air dryer, granular light burnt magnesium was obtained, and this sample was used as prototype 4 for testing. Example 5 2.19 kg of hydrotalcite powder was added to 5.98 kg of lightly calcined magnesium and mixed in a kneader. Add 1.83 kg of magnesium-based lignin sulfonate solution to the mixed light calcined magnesium containing hydrotalcite powder, and further mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. The sized sample was dried in a hot air dryer to obtain granular lightly burnt magnesium, and this sample was used as prototype 5 for testing. Example 6 Lightly baked magnesium 7.26Kg and lime cake 0.95Kg
and mix using a kneader. Add 1.79 kg of magnesium-based lignin sulfonate solution to the mixed light baked magnesium with lime cake, and further mix with a kneader. The mixed sample is molded using an extruder and then sized through a rolling granulator. The sized sample was dried in a hot air dryer to obtain granular light burnt magnesium, and this sample was used as prototype 6 for testing. Table 2 shows the moisture absorption and hardness change test results for Samples 1 to 6 obtained in the above six Examples.
The soil disintegration test results are shown in Table 3. The results shown in Table 2 are the measured values of moisture absorption when 10g of a sample with a particle size of 2000 μm or more was placed in a desiccator using a CaCl solution and maintained at a temperature of 20°C and a RH of 70%. This is the average value obtained by measuring the hardness of 30 samples each with a diameter of 2000 μm or more. The results of this test show that prototypes 1 to 3 have extremely low moisture absorption rates and are stable even when placed in high humidity. The hardness also showed an effect on the caking phenomenon, with an increase of about 13% to 16%. Prototypes 4 to 6 show a slight increase in moisture absorption and hardness compared to prototypes 1 to 3, but these are within a practical range as fertilizer. It turns out that. The test results shown in Table 3 were obtained by selecting 50 samples each with a particle size of 2,000 μm or more using a sieve, as in the case of the tests in Table 2, and conducting an underwater disintegration test on the samples. It was subjected to a disintegration test. For the underwater disintegration test, 50 grains of a sample left indoors (A) and a sample packaged in a bag (B) were placed on a sieve, placed in a container, water at the same temperature as room temperature was poured into the sample until the sample was fully diluted, and left to stand overnight. After gently removing the sieve, the undisintegrated particles remaining on the sieve were counted, and the disintegration rate was determined. For the disintegration test in soil, 50 bagged samples were placed in a 100ml beaker, 50g of dry soil was added and mixed, water was added to make it 60% of the maximum water capacity of the soil, and the beaker was sealed with plastic. A disintegration test similar to the underwater disintegration test was performed on the product left for one week to determine the disintegration rate. As a result, in the water disintegration test, the bagged sample showed a complete disintegration rate, and the indoor disintegration test and the soil disintegration test also met the requirements of the administrative guidance of the Fertilizer Control Law. (3) Effects of the invention As described above, the method for producing collapsible light-calcined magnesium based on the present invention allows it to be used as a raw material for bulk blend fertilizer without deterioration due to moisture absorption and with sufficient hardness during storage. It maintains its granular form without turning into powder, is extremely easy to handle, and is easily disintegrated by the moisture in the soil during spraying, making it an excellent fertilizer.

【table】

【table】

[Table]
*Hardness is the average value of 30 samples with a diameter of 2 mm or more placed under the above conditions.

【table】

[Table] * The disintegration test is based on the disintegration test guidance guidelines of the Fertilizer Control Law.
*Bagged samples are used for soil disintegration tests.

Claims (1)

[Claims] 1. A lignin sulfonate solution substituted with a magnesium base or a sodium base is added to light calcined magnesium powder as a granulating agent, and at least one of lime cake, brucite powder, and limestone powder is added as a granulating agent. 1. A method for producing collapsible granular lightly calcined magnesium, which comprises adding and mixing a dispersing agent, granulating it, and then drying it. 2. The method for producing collapsible granular lightly calcined magnesium according to claim 1, wherein the granulation molding is performed by rolling granulation after extrusion molding. 3. The method for producing collapsible granular light-sintered magnesium according to claim 1, wherein the granulation molding is performed by rolling granulation. 4. The method for producing collapsible granular light-sintered magnesium according to claim 1, wherein the granulation molding is performed by extrusion molding.