JPS6140890A - Manufacture of granular 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 (a) Purpose of the Invention [Field of Industrial Application] The present invention relates to a method for producing granular fertilizer, and in particular, to effectively use a material that is a raw material for granular fertilizer but has low value due to water content, etc. The aim is to obtain granular fertilizer with excellent granulation efficiency.

[Conventional technology]

The productivity and energy consumption of granular fertilizers depend largely on granulation efficiency, and for many years the manufacturers have
We have been working hard to improve this.

In the manufacturing process of granular fertilizer, the granulation methods used are transfer granulation, i.e., mainly by rotating drum, or by rotating plate type, or variations thereof. , a method of dispersing powder raw materials directly and rolling granulation, or a mixing machine such as a pug mill or edge runner is installed as a pre-process to prepare the wet powder in advance, and then granulating it by rolling. There are methods such as transfer granulation.

The powder raw material introduced into the granulator is joined by the added liquid to form loose aggregates. As the particles are transferred, they are tightened, the voids between the particles are reduced, and liquid is present on the surface of the aggregate, and when this liquid comes into contact with the small pieces, they are swallowed together to form a larger aggregate. This aggregate grows by transfer and becomes a Y-sphere, and compaction progresses, and eventually the liquid is released from the surface of the granule due to capillary force.
It is drawn into the interior and becomes a stronger granule. This granule is dried and dehydrated in a dryer in order to make a complete granular fertilizer. Next, the fertilizer is sieved to obtain a granular fertilizer with a diameter of about 1 to 4% in order to select the desired particle size. Oversized and undersized fertilizers are ground again and returned to the granulation process as fine powder.

The ratio of product yield to the amount passed through this granulation process is called granulation efficiency, and the granulation efficiency in the production of granular fertilizer is
The type of fertilizer to be produced, for example, the total of nitrogen compounds, phosphoric acid compounds, and potassium compounds, is N, P, 0. , high-grade chemical fertilizers containing more than 30 parts of K20, low-grade chemical fertilizers containing less than 30 parts, organic chemical fertilizers containing bark powder and other organic matter, and even the same type of chemical fertilizers. , depending on the type of compound formed, for example, in the case of nitrogen compounds, either urea or ammonium sulfate, or depending on the ratio of amounts of the cages used simultaneously, or alternatively, nitrogen compounds,
It depends on the amount ratio between each of the phosphoric acid compound, potassium compound, etc., so it is difficult to say generally, but it is between 30 and 70.
It varies over a wide range of areas. Even if the ingredients of each fertilizer are the same, the granulation efficiency is affected by the amount of sprayed liquid, its physical properties, the method of spraying, the presence or absence of a binder in the granulator, its amount, its type, etc.

Water is often used as a spraying liquid.

When mixed in advance before granulation, the washing water used for washing the drying gas is often used.

Fresh water is sometimes used as the water to be sprayed directly to the granulator, taking into consideration the possibility of clogging of the spray port. Sulfuric acid or ammonia may also be added therein, and steam may also be sprayed.

On the other hand, ammonium sulfate is generated from some processes in chemical factories, such as ammonia synthesis process, its transportation equipment, neutralization and other reactions in various chemical reaction processes, metal refining process, drug manufacturing process, etc. There are water-based solutions such as ammonium hydrochloride, nitrates, and phosphates, and their use is expected from the perspective of resource conservation.

[Problem that the invention seeks to solve]

As a method for recovering the active ingredients of fertilizers generated at the above-mentioned chemical factories and other places, it is expected that they will be used as additives in the granulation process of crude liquid fertilizer. depends on its concentration, but
It definitely lowers the granulation efficiency and is not legal. The extent of this decrease in granulation efficiency varies depending on the type and quantity of the high-grade chemical fertilizer, low-grade chemical fertilizer, or organic chemical fertilizer mentioned above, as well as nitrogen compounds, phosphoric acid compounds, potassium compounds, etc. However, sometimes it can be halved.

Therefore, even if an attempt is made to recover these active ingredients, it may not be possible to make ends meet in terms of energy loss.

As a result of many years of research and consideration into improving granulation efficiency and the use of active ingredients generated from chemical processes, the inventors have found that it is possible to significantly improve granulation efficiency and recover active ingredients at the same time. We developed a method and completed the present invention.

Naka) Structure of the Invention [Means for Solving the Problems] The present invention provides at least one of the fertilizer elements nitrogen, phosphoric acid, and potassium.
It is made by blending a solution or mud crystalline liquid in which a crystalline substance is present with a fertilizer whose main component is seeds, and the state of the solution or mud crystalline liquid is such that the above-mentioned crystalline substance is not present. It is either in a supersaturated state in a water-based solvent, in the presence of microparticles, or in a state in which microcrystals are growing.

The above-mentioned crystalline substances are desirably those which themselves can be effectively used as fertilizer components, and the following compounds are preferably used.

Namely ammonium sulfate, ammonium hydrogen sulfate, ammonium magnesium sulfate, ammonium hydrochloride, ammonium nitrate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate, potassium ammonium hydrogen phosphate, ammonium bicarbonate, potassium nitrate, Calcium nitrate, sodium nitrate, magnesium nitrate, urea, potassium phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate,
These include sodium dihydrogen phosphate, calcium dihydrogen phosphate, potassium chloride, potassium sulfate, magnesium chloride, magnesium sulfate, etc., or a mixture of two or more of these.

The above-mentioned crystalline substances are made to exist in a solvent mainly composed of water, but the solvents for Kitori include alcohols such as methanol, ethanol, isopropanol, formic acid, acetic acid,
Examples include organic acids such as 7 minic acid, inorganic acids such as sulfuric acid, phosphoric acid, hydrochloric acid and nitric acid, ketones such as acetone, methyl ethyl ketone, and acetaldehyde, aldehydes, and others.

The formulation can be made using a mixer before the granulator in the granular fertilizer production process, a transfer granulator, or an alcoholic fermentation residue, lignin sulfite, etc.

As mentioned earlier, the granulation efficiency varies depending on the type of high-grade chemical fertilizer, low-grade chemical fertilizer, organic chemical fertilizer, nitrogen compound, phosphoric acid compound, potassium compound, etc., and the ratio of their amounts, as well as the binder. The presence or absence of this also contributes greatly.

If the method of the present invention is directly applied to a binder that uses, for example, alcoholic fermentation residue to obtain high granulation efficiency, it will result in excessive granulation, resulting in a large number of large-diameter particles, which will actually result in granulation. This may result in a decrease in grain efficiency. At this time, it is necessary to reconsider the amount of binder added.

The blending amount of the solution or mud crystal liquid containing the above crystalline substances is as follows:
Depending on the solubility of the crystalline substance, its hydrophilicity is between 6 and 8.
Although it seems that the granule size has good granulation efficiency and is economical, this cannot be said because of the drying process capacity, fuel cost, etc. Therefore, the maximum amount of the solution or mud crystal liquid is determined in consideration of the moisture in the raw materials, the moisture added to the granulator, etc. The larger the amount added, the better the granulation will be, but the economical optimum amount differs depending on the individual granular fertilizer, so it is desirable to determine it on an individual basis after trial.

With this N, the method of the present invention can utilize crystalline substances that are by-products or discharged in processes such as chemical factories, metal refining, and drug manufacturing.

Examples include dilute ammonium sulfate or ammonium hydrochloride produced in the oximation process of ketones and aldehydes, and anthonium nitrate and phosphate obtained during metal refining and drug manufacturing, but many of these byproducts have low concentrations. The ammonium sulfate generated in the oxime process has a concentration of 20 to 30%, and if this is directly fed into the granulation process of the present invention, the granulation efficiency will be worse than when simply using water. It becomes a trend.

Therefore, although ammonium sulfate is useful as a fertilizer, it is economically worthless or may become a negative additive.

Fortunately, a large amount of waste gas is generated during the drying and cooling steps during the manufacturing process of granular fertilizer, and a process is often included to wash away fertilizer components and other fine particles floating in the waste gas.

When ammonium sulfate generated in the chemical factory mentioned above is used as a washing liquid in the above process, a part of the volatile matter is evaporated and concentrated, resulting in a nearly saturated solution. Even if they are blended, it does not lead to a significant improvement in granulation efficiency.

The present invention actively saturates the crystalline substance in the liquid after washing and removing the fine powder in the waste gas to generate crystals of the active ingredient to form a mud crystal liquid, which is incorporated into the granulation process. By adding it, it is possible to economically recover the fertilizer active ingredients and obtain granular fertilizer with excellent granulation efficiency that overwhelmingly exceeds conventional granulation efficiency with a high blending amount.

[Effect].

In the present invention, the granulation efficiency can be dramatically improved by blending the fertilizer with a solution or mud crystal liquid in a supersaturated state of crystalline substances, a state in which microparticles are present, or a state in which microcrystals are growing. It is improved, but the reason is not clear.

As can be seen, the raw material fertilizer has particles with a significantly larger diameter than the crystalline substance, and the crystalline substance enters between the grains of the fertilizer powder as a supersaturated solution or small crystals on the order of microns.
This seems to be because small crystals rich in surface activity adhere to the powder wall surface and contribute to the bonding of both powders.

〔Example〕

As mentioned above, one of the advantages of the present invention is that it is possible to effectively utilize crystalline substances produced as by-products in other factories. The embodiment will be described below with reference to the drawings.

That is, FIG. 1 is a process diagram showing an example of the method of the present invention,
Reference numeral 1 denotes a mixing tank, in which a fresh liquid of the crystalline substance is fed through tube 6, and a part of the solution from which most of the crystals have been separated in a crystal separator 12 (to be described later) is used as a circulating liquid, and is fed through tube 2. Inject and mix. This circulating fluid is usually several to several ten times the amount of the new fluid.

Although it is expected that the supersaturation of the circulating fluid will be reduced in the mixing tank, during operation, this may not necessarily be necessary. If necessary, acid or alkali is introduced through the pipe 4 to adjust the pH of the tank liquid, and water is also introduced as necessary.

The liquid leaving the mixing tank 1 is sprayed into a washer 6 through a pipe 5. The waste gas generated in the granulation process of the present invention or the drying or cooling process (not shown) of the granulation process in other granular fertilizer production is fed into the washer 6 through a pipe 7 to remove the waste gas contained. A portion of the dust that has been stored is transferred to the liquid side, and a portion of the volatile matter is transferred to the gas side and concentrated to form a supersaturated liquid.

The dedusted waste gas leaves through the pipe 8, and if necessary, is further removed by a Cottrell or the like. The supersaturated solution containing dust is passed through a tube 9 into a crystal growth tank 16 to grow crystals. There is usually no need to add seeds to maximize the number of crystals.

The generation of crystals occurs smoothly, probably because the captured dust becomes seeds. The mixed crystals are fed from the crystal growth tank 10 to the crystal separator 12, and most of the crystals and a part of the solution are fed to the granulator 15, where they are mixed with the powdered fertilizer fed through the input port 16. The solution that has lost most of its crystals is returned to the mixing tank 1 again. The crystal separator 12 is equipped with a water injection pipe 1'5 in case the operation is stopped.
etc. are provided.

The thus granulated fertilizer is taken out as a product through the outlet 17.

The present invention will be further explained below with reference to Examples and Comparative Examples.

Example 1 For the production of granular fertilizer (N-P-K) 11-8-10, 420kyj8-461J of ammonium sulfate per fertilizer
ammonium phosphate 87k), 17% lime superphosphate 254
Q. The chloride power IJ173ky- is turned into powder, and the pulverized powder 8'l"/H is circulated as fertilizer.

On the other hand, 25 tons of ammonium sulfate aqueous solution 2,800kt
/H was supplied to the mixing tank, mixed with 50 T/H of circulating fluid, and sprayed into the washer to contact with the waste gas.

The spray liquid with some dust trapped enters the crystal growth tank of 1 (0), and is then pumped up from the bottom of the tank and sent to the crystal separator at a rate of 9 T/H to collect 1.080 kl of ammonium sulfate saturated liquid containing crystals. It was supplied to the pug mill and mixed into powder fertilizer.The pug mill was supplied with 7 (liters of sulfuric acid 600 kg) from a separate outlet.
ll/H was added and blended. The blended mixture was sent to a drum-type granulator and granulated by spraying water, and then subjected to a drying process, a cooling process, and a granulation process to form a product. The yield was 14T/H.

Comparative Example 1 In the production of the same granular fertilizer as in Example 1, 1.400 kp/H of 25% ammonium sulfate was mixed into the circulating fluid 5QT/H. In order to adjust the concentration (approximately 65 cm) of the circulating fluid,
'I replenished water at a rate of about 500 kp/h. Excess IT/H of the circulating fluid was sent directly from the mixing tank to the pug mill and blended into powder fertilizer.

The total amount of fertilizer mixed in the pug mill was 22 T/H, both new and old, and the granular fertilizer that could be obtained as a product was 7 T/H. Granulation efficiency was 62 cm.

In this case, attempts were often made to increase the yield, but 8-9T
/H, the granular fertilizer lost its shape within a few hours, and the supply of new raw materials had to be stopped and circulation operation started.

Example 2 Granular fertilizer (N-P-K) 11-8-10 as in Example
In the production of 440 kg of ammonium sulfate per 1T
, 17% lime superphosphate 255k1. Potassium chloride 173k)
and 18-46 ammonium phosphate 81k) were fed to the pug mill at 13 T/H as powder raw materials. The amount of circulating powder was also 8T/H as in the previous example.

On the other hand, 25% ammonium sulfate aqueous solution 2,450kI
P/H ammonium triphosphate 25% aqueous solution 350ky
/H was sent to the mixing tank as in the previous example. Other conditions were the same as in Example 1, and the amount of product obtained was 14 T/H.

(c) Effects of the Invention According to the present invention described above, by blending and using a crystalline substance in the fertilizer as a solution or mud crystal liquid in the above-mentioned state and granulating it, granules can be formed with extremely high granulation efficiency. Fertilizers can be manufactured that have a lower content of phosphoric acid compounds, which are considered to have lower granulation efficiency even in the fertilizer industry, or that contain higher amounts of nitrogen, phosphoric acid, and potassium compounds. When applied to products, the granulation efficiency of the conventional method was 60 units, but it can reach up to 60%.

In addition, by using fertilizer active ingredients as a crystalline substance by-produced from other factories, it is possible to effectively utilize the by-products and to obtain granular fertilizer at an economical cost.The present invention has industrial advantages in these respects. This is a valuable invention.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an example of the method of the present invention. 1...Mixing tank 6.--- Washing machine 10...Crystal growth tank 12...Crystal separator 15... Granulation device

Claims (1)

[Scope of Claims] 1. For a fertilizer containing at least one of nitrogen, phosphoric acid, and potassium as a main component, one or two crystalline substances
Contains a solution or mud crystal liquid in which seeds or more are present in a water-based solvent in either a supersaturated state, in the presence of microparticles, or in a state in which microcrystals are growing. A method for producing granular fertilizer, characterized by granulating it. 2. The mud crystal liquid in which the microcrystals are growing is a mud crystal liquid containing ammonium sulfate that was used to wash dust in the gas used in the drying or cooling process in the production of granular fertilizer. A method for producing granular fertilizer according to scope 1.