JPS59128289A - Manufacture of potassium silicate fertilizer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing soluble potassium silicate fertilizer using potassium sulfate as a potassium source.

The soluble potassium silicate fertilizer does not dissolve in water, but is dissolved by citric acid excreted from the roots of plants, so it has the advantage of having a long shelf life as there is no drainage outlet for rainwater. In recent years, in order to produce this kind of soluble potassium silicate fertilizer, a method has been implemented in which dust in exhaust gas generated from pulverized coal combustion furnaces such as thermal power plants, that is, fly ash, is mixed with a potassium source and fired in a furnace. It is being done. In this case, potassium carbonate and potassium hydroxide are generally used as the potassium source. Potassium carbonate and potassium hydroxide react as shown in the following formula upon calcination to produce soluble potassium silicate.

(a) Kz COs −> Kz 0+2 to CQ2
0+n Si 02-+Kz O・n Si2 (L)) 2KOH->Kz 20+n to Kz O+820
Si 02-+Kz O・n Si2 That is, each potassium compound is decomposed by calcination to produce potassium oxide, and this potassium oxide reacts with silicon dioxide contained in the fly ash to produce soluble potassium silicate. be.

However, this method requires a firing temperature of 800 to 1000°C to decompose potassium carbonate and potassium hydroxide, but it is known that the higher the firing temperature, the lower the elution rate by citric acid. However, the produced potassium silicate had the disadvantage that it was difficult to be used by plants.

A method using potassium sulfate as a potassium source has also been proposed (see, for example, Japanese Patent Application Laid-Open No. 55-20218).

In this method, the reaction is as follows.

KZ 804→20+5O3 KZ Qten si 02-+Kz Q-n si 0
2 However, this method requires a higher firing temperature to decompose the potassium sulfate, and the sulfur trioxide generated is corrosive.

Therefore, an object of the present invention is to provide a method for producing potassium silicate fertilizer that has a high elution rate with citric acid by lowering the firing temperature.

According to the present invention, a method for producing potassium silicate fertilizer uses C fly ash, potassium sulfate, and pulverized coal as starting materials, mixes these materials, granules them, dries them, and burns them in a kiln. In the firing process, pulverized coal forms a reducing atmosphere, and the firing temperature is between 500 degrees Celsius and 800 degrees Celsius.
degree C.

Therefore, potassium sulfate reacts as shown in the following equation.

KZ S 04 + (1/2) G-KZ 0 + 8
02+○/2) Cox KZ 0+n Si Oz ->Kz O・n Si
02 Since this reaction proceeds at a relatively low temperature, about 500 to 800°C, it is possible to produce a potassium silicate fertilizer with a high citric acid elution rate by lowering the calcination temperature. Further, the generated sulfur dioxide can usually be sufficiently treated with an A4 non-smoke desulfurization equipment.

A technique for producing potassium silicate fertilizer using pulverized coal as a starting material is described, for example, in JP-A-55-104987. However, according to the known technology, the firing humidity is 90
Since pulverized coal was used as a heat source to obtain such a high temperature, the above-mentioned drawbacks were unavoidable.

According to the present invention, pulverized coal is used as a reducing agent, and sulfur trioxide generated from potassium sulfate is reduced to sulfur dioxide, so treatment is easy and does not cause pollution problems, and the reaction takes place at a relatively low temperature. The effect of being able to produce
J- can do it.

Next, an apparatus for implementing the present invention will be explained according to the drawings.

In the figure, Δ is fly ash, B is potassium sulfate,
C is a hopper containing pulverized coal, and D is a hopper containing liquid binders such as water and alcohol waste liquid necessary for granulation, and these raw materials are fed to feeders 1.2.3.4, respectively.
is supplied to the mixing l115 at a predetermined mixing ratio.

After thoroughly mixing these raw stones in a mixer 5, they are sent to a pulverizer 6 and granulated to a diameter of about 2 to 5+ nm. Furthermore, the granulated raw material is sent to a dryer 11i7 and dried. The temperature of the hot gas used for drying is 300-400℃, and the drying time is 1
Kneading for 0 to 20 minutes is appropriate. Then, the dried raw material is sent to the firing furnace 8 and heated to 500 to 800 ml under a reducing atmosphere.
Bake at ℃. The type of firing furnace 8 is a rotary kiln,
Exclusive fluidized furnaces and electric furnaces can be used. By firing in this manner, potassium sulfate decomposes as described above to become potassium oxide, and further reacts with silicon dioxide in the fly ash to become soluble potassium oxide.

The exhaust gas generated by firing consists of sulfur dioxide, carbon dioxide, carbon oxide, etc., and contains almost no sulfur trioxide. The produced potassium silicate is taken out as a product from the calcining furnace 8, and the exhaust gas is sent to the secondary combustion chamber 9 where air is added to reburn it. The secondary combustion chamber 9 may be separated from the firing furnace 8 as shown in the figure, or the secondary combustion chamber 9 may be separated from the firing furnace 8 as shown in the figure.
It may be integrated with. This re-burned gas is sent to the dryer 7 to be used as a heat source for the dryer 7, and further sent to the scum cleaning device 10 to remove sulfur oxides and then released into the atmosphere. Note that 11 is a burner for the firing furnace 8;
2 is a supply air blower, and 13 is an auxiliary burner for the secondary combustion chamber 9.

Example Potassium silicate was produced using the apparatus shown in the figure.

First, from feeder 1.2.3.4, fly ash 3
4.5 kg, potassium sulfate 17 kg, coal powder 1 kg, and water 6 kg are supplied to the mixer 5, and after mixing well, the granulator 6
to granulate particles with a diameter of about 3 mm.

This granulated raw material was put into a dryer 7 and heated to 200℃ for 20 minutes.
After drying for a minute, put it in a firing furnace (electric furnace) and heat it to 650℃.
It was baked for 40 minutes. As a result, potassium silicate fertilizer 4-3
I was able to obtain kc+.

Incidentally, the elution rate of the potassium silicate fertilizer taken out from the firing furnace 8 with respect to citric acid is 60%, which is a much higher value than the elution rate of potassium silicate of 45% obtained by the conventional method.

According to the present invention, as described above, since it can be produced at a relatively low calcination temperature, a potassium silicate fertilizer with a high citric acid elution rate can be produced. Furthermore, since the exhaust gas contains almost no sulfur trioxide, it is easy to treat the exhaust gas.

[Brief explanation of drawings]

The figure is a flow sheet showing an apparatus for carrying out the invention. 1.2.3.4... Feeder 5... Mixing Ia
6... Granulator 7... Dryer 8... Calcining furnace
9... Secondary combustion chamber 10... Gas washer 1
1...Burner 12...Air supply blower 13.
...Auxiliary burner patent applicant Ken Nakagawa - Kado 1) Masahiko

Claims (1)

[Claims] A method for producing potassium silicate fertilizer in which fly ash, potassium sulfate, and pulverized coal are used as starting materials, and these raw materials are mixed, granulated, dried, and then fired in a kiln, in which the pulverized coal is reduced in the firing process. 1. A method for producing a potassium silicate fertilizer, characterized by forming a neutral atmosphere and firing at a temperature of 500 degrees Celsius to 800 degrees Celsius.