JPS5930675B2 - Porous granulation method of slaked lime - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming slaked lime into porous granules.

Slaked lime is used as a soil improvement material to fertilize fields with a spreader, but because it is in powder form, it is highly dispersed and its spreading effectiveness is reduced, especially in windy conditions.

Furthermore, it is difficult to handle when packing bags, etc., and work efficiency is not good.

Therefore, in the past, as disclosed in Japanese Patent Publication No. 47-13084, granulation method by adding water, or as shown in Japanese Patent Publications No. 54-24943 and No. 54-28348, Steffen wastewater concentrate or alcoholic fermentation waste liquid was used. In addition, methods have been proposed for mixing and preventing scattering.

However, in the former method of granulation, water is added to slaked lime to form granules, and carbon dioxide is adsorbed to harden the surface as carbonated lime. Only the outer peripheral surface of the grains comes into contact with each other, and especially when the granules become large, the contact area with moisture becomes small compared to the mass of the grains, and as a result, they are difficult to disintegrate and dissolve in water, and The reaction rate is also low compared to weak acids.

The original purpose of fertilizing slaked lime is to neutralize the soil by reacting with the moisture in acidic soil, and by granulating it to prevent scattering, slaked lime can not fully demonstrate its original function. It's gone.

Next, in the latter scattering prevention method, slaked lime is mixed with Steffen wastewater concentrate (hereinafter referred to as rC8FJ).

) and alcohol fermentation waste liquid concentrate (hereinafter referred to as rCCDSJ).

) is simply mixed and kneaded, and the amount of addition and kneading time vary depending on the particle size distribution of lime, the concentration of added C8F and CCD5, temperature, etc. It takes skilled technology to manufacture the product. is necessary.

In addition, the additives C8F and CCD5 in the product are extremely hygroscopic, so when the weather is bad, and when spraying on fields in rainy or humid conditions, the anti-dispersion lime will cause a bridging phenomenon in the tank of the prodocatter, causing the 7-revolution plate to drop. There are also disadvantages such as uneven distribution because the particles do not fall evenly.

The present invention was developed in view of the above-mentioned circumstances, and it makes it easy to mechanically spread slaked lime and handle it, and it also disintegrates and dissolves easily in water and does not reduce the reaction rate with weak acids. Another object of the present invention is to provide a method for forming porous particles.

In the present invention, slaked lime refers to the one based on the Fertilizer Control Law, that is, the one obtained by digesting oxidized lime (quicklime) (calcium hydroxide), the calcined dolomite (magnesium carbonate,
Digested with calcium (magnesium hydroxide) and mixtures thereof.

The present invention consists of a kneading process in which slaked lime is mixed with a granulating agent containing an organic substance such as C8F, CCD5, or a phosphorus sulfonate solution and kneaded under high pressure, and a pulverization process in which the kneaded slaked lime is scattered and collided at high speed. It consists of sequentially repeating a granulation process and a drying process in which pulverized and granulated slaked lime is statically dried.

Typical granulating agents containing organic substances used in the present invention are CCD5 from a sugar beet factory using the Steffen process, CCD5 from a C3F1 alcohol factory, and lignosulfonate solution obtained from a paper factory. 80
%, but it is also possible to use waste liquids containing other organic substances having a viscosity similar to that of the above-mentioned ones.

Next, each process will be explained in order.

First, put slaked lime into the kneader for kneading, and add C8 to it.
A granulating agent containing an organic substance such as F (hereinafter referred to as a ``granulating agent'').

) is added. The ratio of the two differs depending on the type of granulating agent and its water content, but for example, if the granulating agent's water content is 50%.
If this is the case, the granulating agent accounts for about 15 to 25% of the slaked lime, preferably about 20% (weight ratio).

The above-mentioned granulating agent can be used with a water content in the range of 20 to 80%, but the amount added to the slaked lime should be increased or decreased depending on the water content in consideration of the above values.

The slaked lime and granulating agent are subjected to a kneading process under high pressure in a kneader.

Here, kneading refers to kneading enough to uniformly form a granulating agent coating on the surface of fine particles of slaked lime.

The pressure in this process varies depending on the state of the granulating agent, but...
It is carried out appropriately within the range of 25-70-/d.

If this step is carried out sufficiently in the kneader, the granulating agent will fully penetrate into the slaked lime, and each fine particle of slaked lime will be covered with a coating of the granulating agent. They adhere to each other through washing and grow into block-shaped grains.

The degree of growth is sparse and there are some that have not grown sufficiently and some that have grown to the size of 5 to 6 hara.

Next, the slaked lime that has undergone the above-mentioned kneading process is put into a crushing and granulating machine that scatters and collides at high speed to perform a crushing and granulating process.

A pulverizer and granulator may be used as long as the block-shaped particles are scattered and collided with each other at high speed in the machine, but the machine also has blades that rotate at high speed and uses centrifugal force to cause the block-shaped particles to scatter and collide while being crushed by the blades. The format is preferred.

In the main crushing step, the grown block-like grains are once crushed, but the grains adhere to each other again due to mutual collision.

Also, grains that have not grown sufficiently in the previous process adhere to each other, and the grains inside the machine become fine grains of a uniform and constant size.

At this time, the fine particles exhibit porous properties.

Finally, the fine particles obtained in the above-mentioned pulverization step are sufficiently dried in a drying step.

In the drying in this step, the uniformly sized porous particles obtained in the previous step are dried as they are.

That is, drying is carried out in a static state to avoid stirring, especially rolling of the finer grains and collision of the finer grains with each other, thereby preventing the fine grains from being broken or solidified.

If consideration is given to providing continuity between each process and improving work efficiency, a flow dryer is preferable.

The drying time of the drying step is appropriately determined depending on the amount of water contained in the granulating agent used.

In this way, the product obtained by adding a granulating agent to slaked lime and sequentially passing through a kneading process, a crushing granulation process, and a drying process has sufficient strength for handling such as bagging, is easy to handle, and is suitable for use in fields, etc. There is no scattering when spraying, and since the fine particles are porous, the surface area is large, so after spraying, there is enough contact area with the moisture in the soil, and it dissolves quickly in water and is resistant to weak acids. However, the reaction speed was extremely fast.

Examples and their test results will be shown below while comparing them with conventional ones. The granulating agent used in each example had the following components and viscosity.

Example 1 C3F1 with a moisture content of about 50% for agricultural slaked lime 8.5 ~
．． 7 is added and kneaded in a kneader.

The pressure is approximately 40 f/i.

Kneading time is 10-18 minutes and moisture content is 11-12%.
Block-shaped grains were obtained.

1,500 rpm to 1,70 Orp for the grinding process
Using a crusher equipped with crushing blades attached perpendicularly to a high-speed rotating shaft of m, block-shaped grains are introduced from the top and porous fine grains are taken out from the bottom.

These fine particles are irregularly shaped small particles of 1 to 2M in size, in which the structural surface of the slaked lime is coated with C8F organic matter and the particles are continuous.

By removing excess moisture from this product using a flow dryer, it was possible to obtain a product of irregularly shaped small particles of 1 to 271 gl1 in which the structural surface of slaked lime was coated with organic matter.

This product was used as prototype 1 and was subjected to physical property and chemical analysis.

Example 2 Using the same method as in Example 1, 51.5~ of CCD with a water content of about 50% was added to 8.5~ of agricultural slaked lime, and the mixture was kneaded under pressure.
A product was obtained through crushing and drying.

The shape of this product was the same as in Example 1, and it was used as a prototype 2 for physical property and chemical analysis.

Example 3 Using the same method as in Example 1, a sulfonic acid solution with a water content of about 50% was added to 1.7 Kp of agricultural slaked lime 8.5 to 9.
A product was obtained through pressure kneading, pulverization, and drying.

The shape of this product was the same as in Example 1, and it was used as a prototype 3 for physical property and chemical analysis.

Test Results 1 Regarding the prototypes 1, 2 and 3 obtained in Examples 1, 2 and 3, the products obtained by the conventional method (shown as "conventional product").

), the results of physical property tests and chemical analysis are shown in Tables 2 A and B, respectively.

However, the conventional product was obtained by the following method and was also used in the following tests.

Water is added to agricultural slaked lime to bring the water content to approximately 30%, and the mixture is mixed using a commonly used paddle mixer for light kneading.The mixture is then placed in a pan-shaped granulator (45° inclination) for about 10 minutes. Granules of slaked lime were obtained by granulation and drying in a drum dryer (burner temperature: 680° C., rotation speed: 5 rpm) for 20 minutes.

This experiment was conducted using a general manufacturing method in which slaked lime was granulated with water and dried.In a moisture-containing situation, the concentration of carbon dioxide gas generated from the burner was approximately 18%, and the residence time of this product in the dryer was 20 minutes. It is carbonated and becomes a spherical granulated product.

The crosstalk pressure in the paddle mixer is 0.2 to 0.3 K7/
d is a kneading method that requires very little pressure.

Test Results 2 The carbon dioxide content of Prototypes 1, 2.3, conventional products, and the raw material slaked lime, as well as carbonated lime, was determined, and the amount of carbon dioxide adsorbed by the prototypes during the manufacturing process or while they were left indoors was measured. It is.

The prototype and slaked lime were granular products with particle sizes ranging from 1 to 2 mm that were left indoors for 24 hours and 60 days after obtaining the products, and the slaked lime was used as a powder.

Carbonic acid was determined by increasing the amount of potash spheres, and carbonate lime was determined by ignition loss. The results are shown in Table 3.

If slaked lime Ca (OH) 2 is left alone, it generally reacts with carbon dioxide gas CO2 in the air and gradually changes into calcium carbonate CaCO3.

When this calcium carbonate is heated, it releases carbon dioxide gas and becomes quicklime CaO, and when it is reacted with water H20, it returns to slaked lime.

This means that if you measure the carbon dioxide gas released by heating the slaked lime after it has been left to stand, you will be able to determine the extent to which the deterioration of the slaked lime progresses while it is left, that is, the greater the amount of carbon dioxide released, the more the deterioration has occurred. This means that it can be determined.

From Table 3, it can be seen that after being left for 24 hours and 60 days, prototypes 1, 2, and 3 all emit significantly less carbon dioxide than the conventional product, that is, they do not deteriorate in quality and their shelf life is even better. It turned out that

In other words, it shows that it maintains its high water absorbency until it is sprayed on rice fields, etc.

Test results 3 This test example determined the reactivity to weak acids.

Prototypes 1, 2, 3 and the conventional product were left indoors for 60 days after production, and were classified and sorted. 150 grams of pure water was added to 15 grams of material with a particle size in the range of 0.5 to 1 m, and 2N was added while stirring with a stirrer. The sulfuric acid was made into droplets, the amount of sulfuric acid added was set to be the amount that would maintain the pH of the sample in the beaker, and the reaction rate was determined from the amount of the sulfuric acid added, as shown in FIG. 1.

[Brief explanation of the drawing]

FIG. 1 shows the reactivity with dilute sulfuric acid for Test Results 3.

Claims (1)

[Scope of Claims] 1. A kneading step in which a granulating agent containing an organic substance is added to slaked lime and kneaded under high pressure, a pulverization and granulation step in which the kneaded slaked lime is scattered and collided at high speed, and pulverization and granulation. A porous granulation method for slaked lime characterized by sequentially performing a drying step of statically drying the slaked lime. 2. The method for porous granulation of slaked lime according to claim 1, wherein the granulating agent containing organic matter is a Steffen wastewater concentrate. 3. The method for porous granulation of slaked lime according to claim 1, wherein the granulating agent containing organic matter is an alcohol fermentation waste liquid concentrate. 4. The method for porous granulation of slaked lime according to claim 1, wherein the granulating agent containing an organic substance is a lignosulfonate solution.