JPH08283016A - Production of cyanamide aqueous solution - Google Patents

Abstract

PURPOSE: To produce a cyanamide aqueous solution which is easy to treat a residue from lime nitrogen. CONSTITUTION: In this production method of the cyanamide aqueous solution, an aggregation of lime nitrogen is brought into contact with water and/or cyanamide aqueous solution and concentration of the cyanamide aqueous solution is increased and it is recovered. In this method, the aggregation lime nitrogen is preferably stored in a water permeable container for housing the granular lime nitrogen. Besides, in this method one or >=2 aggregations of lime, nitrogen form a fixed bed and a 30-35 deg.C cyanamide aqueous solution is preferably circulated through the bed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aqueous solution of cyanamide from lime nitrogen which can be used as a pesticide that can be easily applied.

[0002]

2. Description of the Related Art Conventionally, it is known that cyanamide, which is the main component of lime nitrogen, develops a pesticide effect for about a week and then changes into a nitrogen compound such as urea to produce a fertilizer effect. . The pesticides have various effects such as insecticidal, herbicidal, and bactericidal, and an aqueous solution of cyanamide is used for awakening dormancy of fruit trees and withering of potato stems.

[0003]

However, since the pesticide registration of the cyanamide aqueous solution has not been obtained yet, the user had no choice but to make it by himself. Further, since the cyanamide aqueous solution is unstable, treatment with chemicals or the like is required to stabilize it, resulting in a problem of high cost. Therefore, at present, users are using powdered lime nitrogen at the site of use while stirring it to produce an aqueous cyanamide solution, but this method involves stirring work, sedimentation and separation of residues, scraping of residues, etc. Since it was necessary, the work was extremely complicated and the productivity was poor.

An object of the present invention is to produce a cyanamide aqueous solution which does not have the above-mentioned drawbacks by increasing the productivity from lime nitrogen by a simple operation.

[0005]

That is, the present invention is characterized in that the aggregate of lime nitrogen is brought into contact with water and / or a cyanamide aqueous solution to increase the concentration of the cyanamide aqueous solution, and the cyanamide aqueous solution is recovered. And a method for producing an aqueous solution of cyanamide, characterized in that the aggregate of lime nitrogen is one in which powdered particles of lime nitrogen are stored in a water-permeable container, and in this method, A method for producing an aqueous cyanamide solution, which comprises forming a fixed bed with one or more aggregates of lime nitrogen and circulating an aqueous cyanamide solution at a temperature of 30 to 35 ° C therein.

The present invention will be described in more detail below.

The lime nitrogen used in the present invention may be either commercially available granular lime nitrogen or powdered lime nitrogen,
Since granular lime nitrogen produced by hydration granulation is poor in disintegration in water, it is desirable to use dry granulation in the case of granular lime nitrogen.

In the present invention, lime nitrogen is brought into contact with water and / or an aqueous cyanamide solution after forming aggregates. As a specific example of the aggregate of lime nitrogen, for example, a container having a bottom plate and a water-permeable container such as a hemp bag, a wheat bag, and a Tonelit bag were filled with powdery lime nitrogen particles having a particle size of about 5 mm or less. It is a compact of powdered or granular lime nitrogen.

In order to bring the aggregate of lime nitrogen into contact with water and / or an aqueous solution of cyanamide, a method of suspending the aggregate of lime nitrogen in water or an aqueous solution of cyanamide and stirring, and an aggregate of lime nitrogen on the upper part of the circulation container are used. To form a fixed bed and spray or circulate water and / or a cyanamide aqueous solution thereon, and further a method of forming this fixed bed in water or in a cyanamide aqueous solution.

In the present invention, one of the aggregates of lime nitrogen is
Alternatively, two or more fixed beds, preferably a plurality of fixed beds, are formed in advance, and while the cyanamide aqueous solution is circulated therein, in the case of a plurality of fixed beds, the cyanamide concentration of the circulating liquid is increased while circulating using a distributor. From the viewpoint of yield, it is desirable to recover. Further, in this case, the higher the liquid temperature of cyanamide, the faster the extraction, but when it exceeds 40 ° C, it becomes dicyandiamide. Therefore, it is preferable to adjust the liquid temperature to 35 to 30 ° C through the heat exchanger.

Furthermore, when the circulation of the cyanamide aqueous solution is insufficient, lime nitrogen tends to solidify and the yield tends to decrease, so the weight of lime nitrogen per aggregate is 1 to 20.
It is desirable that the weight is particularly preferably 5 to 15 kg.

Since the residue of the by-product can be carried in each water-permeable container, the processing operation can be performed easily. The residue can be used as a slaked lime material for soil improvement, compost, fertilizer, etc.

[0013]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples.

Examples 1 to 5 As shown in Table 1, 30 kg of lime nitrogen having a particle size of 0.3 mm is divided into 2 bags, 3 bags or 6 bags of wheat harvesting to be filled with 2, 3 or 6 bags. An aggregate of lime nitrogen was prepared. A fixed bed was formed by these aggregates in the upper space of the circulation container, and the cyanamide concentration of the circulating liquid was measured every hour while circulating 400 liters of water with a pump. Table 1 shows the results. In addition, the residue could be treated as it was in the bag and was hardly mixed into the cyanamide aqueous solution.

Comparative Examples 1 and 2 30 kg of lime nitrogen having a particle size of 0.3 mm was put into 400 liters of water, stirred for 1 hour or 3 hours, and the cyanamide concentration of the aqueous solution was measured. However, it took about 10 minutes for the residue to settle after stirring, and the work of separating and scraping the residue was a very heavy labor.

[0016]

[Table 1]

Examples 6 to 11 80 kg of lime nitrogen was added to four Tonerit bags (20 kg ×
Example 1 except that 4 bags were divided and filled to form 4 aggregates, which formed a fixed bed in the upper space of the circulation container, and sprayed with a shower while circulating the circulating liquid with a pump.
An aqueous cyanamide solution was produced in the same manner as in. Furthermore, in these examples, the circulating fluid is passed through a heat exchanger at a liquid temperature of 30 ° C.
It was circulated while adjusting to. Table 2 shows the results. In addition, the residue could be treated as it was in the bag and was hardly mixed into the cyanamide aqueous solution.

[0018]

[Table 2]

[0019]

EFFECTS OF THE INVENTION According to the present invention, it is possible to increase the productivity of an aqueous solution of cyanamide, which makes it easy to treat the residue, and produce it from lime nitrogen. The cyanamide aqueous solution produced by the present invention can be used as an agricultural chemical, various industrial chemicals, and the like.

Claims (3)

[Claims] 1. A method for producing an aqueous cyanamide solution, which comprises contacting an aggregate of lime nitrogen with water and / or an aqueous cyanamide solution to increase the concentration of the aqueous cyanamide solution and recovering the concentration. 2. The method for producing an aqueous solution of cyanamide according to claim 1, wherein the aggregate of lime nitrogen is a water-permeable container containing powdered lime nitrogen particles. 3. A method for producing an aqueous solution of cyanamide according to claim 2, wherein a fixed bed is formed from one or more aggregates of lime nitrogen and an aqueous solution of cyanamide at a temperature of 30 to 35 ° C. is circulated therein. .