JPS594398B2 - Kankousei Karihiryou no Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing an amorphous slow-release potassium fertilizer using potassium-containing minerals as raw materials.

In the past, various studies have been conducted on methods for producing slow-release potash fertilizers using potash-containing minerals and phosphorus-containing minerals as raw materials, but all methods require excessive alkali to decompose the raw materials. The resulting slow-release potash fertilizer exhibits strong alkalinity.

Needless to say, highly alkaline fertilizers have a negative effect on the germination and growth of plants, and when mixed with ammonia-based fertilizers, the ammonia will volatilize, so they cannot be used in combination with ammonia-based fertilizers.

Therefore, for these reasons, in the conventionally known production method of slow-release potash fertilizer, it is necessary to adjust the pH appropriately by post-processing operations such as neutralization and washing with water. Not only is it difficult to adjust the pH appropriately, but also the soluble components in the slow-release potassium fertilizer become water-soluble during the post-treatment process, and the water-soluble components flow out, causing a loss of fertilizer content. have.

On the other hand, the method for producing slow-release potash fertilizers using potash-containing minerals as raw materials, which is the subject of the present invention, is conventionally a dry method in which potash compounds are mixed with potash-containing minerals and then calcined, or a wet method in which heat and pressure treatment is performed. Two methods are known.

However, in both methods, soluble potash compounds (K2O
・In addition to Al2O3・2Si02), large amounts of water-soluble potassium compounds (K2O・η5in2゜η indicates 2 or 4) are also produced, so the content of slow-release potassium in the resulting fertilizer is extremely low compared to the total potassium. In addition to the disadvantage of low potash, the fertilizer obtained exhibits strong alkalinity as mentioned above due to the use of excess potassium compounds, so post-treatment operations such as neutralization and water washing are required, but these post-treatments Even if you do this, the excess potash cannot be removed sufficiently, and the soluble potash may change to water-soluble potash, or the water-soluble potash may flow into the cleaning solution, resulting in the loss of expensive potash. It has drawbacks such as.

Based on these actual circumstances, the present inventors proposed a method to improve the drawbacks of the conventional method, without using a new potassium source or without post-treatment of pH adjustment. We have conducted extensive research with the aim of establishing a method for producing near-neutral, slow-release potassium fertilizers from potassium-containing minerals.

As a result, if a potassium-containing mineral is mixed with a calcium- and/or magnesium-containing compound, then melted and decomposed at a temperature of 1,100°C or higher, and then water-cooled and pulverized, there is no need for post-processing operations such as neutralization and water washing. discovered that it is possible to industrially produce a neutral, amorphous, slow-release potassium fertilizer, and completed the present invention.

As the potassium-containing mineral used in the present invention, any mineral containing potassium such as potassium feldspar, potassium quartz trachyte, sericite, glauconite, etc. is useful, and these minerals can be used in a 100-inch mesh. It is best to use it by crushing it.

In addition, the calcium and/or magnesium-containing compounds used in the present invention include dolomite, dolomite clinker dust, magnesia lime, limestone, calcium carbonate, quicklime, slaked lime, magnesium calcium carbonate, magnesium hydroxide, magnesium oxide, and serpentinite. Compounds containing calcium, magnesium, or both, such as , magnesite, and molten rock, are useful, and they are preferably used after being ground to about 100-inch mesh.

Considering the yield and slow-release rate of the slow-release potassium fertilizer obtained, the mixing ratio of these should be such that (CaO + Mg0)15io2 (molar ratio) is 0.3 to 1.5. It is preferable to mix calcium and/or magnesium-containing compounds.

Next, this mixture is melted and decomposed using an electric furnace or a rotary kiln at a temperature higher than the melting point of the mixture, that is, at a temperature higher than 1100°C.

If the temperature exceeds a certain level, the effect of melting and decomposing the mixture becomes constant, and if the temperature is higher than that, heating costs will be wasted, and potash will volatilize, so the upper limit of the temperature for melting and decomposing the mixture is 1600℃. is preferable, and it is sufficient if the heating time is about 10 minutes to 3 hours.

Next, after melting and decomposition, water-cooling, pulverization, and drying, an amorphous slow-release potash fertilizer can be obtained.

In this way, the present invention does not require a new potassium source other than potassium-containing minerals, and does not require post-treatment operations such as neutralization and water washing, so it can be used as a potassium source that is more expensive than conventional methods. Not only is the loss extremely low and the manufacturing process simplified, but
It has excellent advantages such as low manufacturing cost,
Furthermore, since almost no water-soluble potassium compounds are produced, it also has the advantage that the content of slow-release potassium obtained in total potassium is extremely high.

Next, examples of the present invention and comparative examples will be given to specifically explain the present invention.

Table 2 shows the properties of the slow-release potassium fertilizers trial-produced on each side.

The potassium-containing minerals used on each side were pulverized 100-inch meshes of potassium quartz trachyte produced in the Yamaguchi region and potassium feldspar produced in Fukuoka Prefecture, having the chemical composition shown in Table 1.

Example 1 Potassium quartz trachyte10. Ok6! Dolomite clinker dust crushed throughout the 100-inch mesh (main components: Ca047, 8 wt%, Mg024.3 wt
%] to 6.15 kg ((CaO+Mg0)/S 1
02 (molar ratio) = 0.8] and then this mixture was mixed with 1
After melting and decomposing in an electric furnace at a temperature of 380°C for 30 minutes, the mixture was water-cooled and pulverized and dried to obtain a slow-release potassium fertilizer of 14.82%.

Examples 2 and 3 The amount of dolomite clinker dust used was 3 in Example 2.
．． 85 kg ((CaO + Mg0)/S 1o2 (molar ratio) = 0.5), in Example 3 7.69 ky ((CaO
The experiment was carried out in the same manner as in Example 1, except that the ratio was 1.0.

Example 4 Dolomite (main component: Ca033.60 wt%
, Mg018.92 w t%) to 7.93 ((C
aO + Mg0) 15i02 (mole ratio) = 0.8), and then this mixture was melted and decomposed in a rotary kiln at a temperature of 1400° C. for 30 minutes, and then water-cooled and pulverized and dried.

Example 5 Calcium carbonate crushed to a 100-inch mesh was added to 8.92 to 9 (CaO
15i02 (molar ratio)=0.8.1 was mixed, and then this mixture was melted and decomposed in an electric furnace at a temperature of 1200° C. for 40 minutes, and then water-cooled and pulverized and dried.

Examples 6-8 The amount of calcium carbonate used was 1338 in Example 6! 9
(CaO/SiO□ (molar ratio) -1,2), in Example 7 it was 10.04! 9 [CaO15io2 (molar ratio)
=0.9. :1 In Example 8, 6.70 kg (CaO/
An experiment was carried out in the same manner as in Example 5, except that S 102 (molar ratio) was 20.6].

Comparative example 1 Potassium quartz trachyte 10. 3 kg at a temperature of 1380℃
After melting and decomposing in an electric furnace for 0 minutes, it was water-cooled and pulverized and dried.

Comparative Example 2 An experiment was conducted in the same manner as in Example 5, except that the melting and decomposition temperature was 1000°C.

*1: The samples trial-produced in Comparative Examples 1 and 2 have extremely low slow-release potash content and cannot be called slow-release potash fertilizers.

Furthermore, all of the slow-release potassium fertilizers sampled in each example were neutral.

In addition, other than those used in each example, the potassium-containing minerals listed above that are targeted by the present invention, or calcium and/or
Alternatively, when a magnesium-containing compound was used, according to the present invention, almost the same results as in each example were obtained.

From the above experimental results, it was found that according to the present invention, it is possible to produce fertilizer with an extremely high content of slow-release potash relative to the total IJg at a high yield, and the present invention is industrially extremely superior. is recognized.

Claims (1)

[Claims] 1. A method for producing a slow-release potash fertilizer, which comprises mixing a potash-containing mineral and a calcium- and/or magnesium-containing compound, followed by melting and decomposition at a temperature of 1100° C. or higher, followed by water-cooling and pulverization.