JPH02267107A - Nitrate briquette and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title briquettes of safe and efficient drug form by dry compression forming of fine granular nitrate pieces as raw material. CONSTITUTION:Fine granular nitrate pieces such as of silver nitrate as raw material R is fed through a hopper 1. It is preferable that the size of said raw material be ca.0.1-3mm and its distribution broad. The raw material R is then pref. put to deaeration treatment in a deaeration tank 2, and fed, through a hopper 3, using a taper screw 4, to a pair of high-pressure kneader rolls 5, where the raw material is subjected to dry compression forming through high- pressure kneader rolls 51, 52 with circumferential pockets 6 of desired size into the objective nitrate briquettes B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a dry compression molding method using a raw material of nitrate fine particles, and particularly to a silver nitrate briquette and a method for producing the same.

BACKGROUND OF THE INVENTION Nitrate salts are generally unstable, alkali metal salts liberate oxygen and turn into nitrites, and heavy metal salts liberate oxygen and nitrogen to form metal oxides or metals. Furthermore, when mixed with organic matter or metals that are easily oxidized, it forms an explosive mixture.

Therefore, sufficient care must be taken to maintain quality and prevent risks during the manufacturing process and storage of nitrates, and even stricter care is required especially in the case of heavy metal nitrates.

Silver nitrate is a typical example of heavy metal nitrates, and is extremely important for use in photography, medicine, and other uses.

Silver nitrate is generally obtained by crystallizing it from an aqueous solution, and when purity is important, it is often precipitated as large crystals. These large crystals are crushed into conveniently sized pieces, washed, centrifugally dehydrated, and stored in a light-shielding container.

Alternatively, the precipitation conditions are adjusted and the crystal pieces of an appropriate size are collected while stirring.

When silver nitrate crystal pieces adjusted to an appropriate size are stored in a light-shielding container, they tend to absorb moisture and solidify during storage, and to prevent this, it is costly to control temperature and humidity. In addition, the solidified crystal fragments require a lot of effort to be disintegrated to take them out during use. In addition, during crushing and feeding during use, the crystal fragments are broken, and the microcrystal fragments that fly off the bullet can cause injury to the human body.
It contaminates the work environment, and furthermore, when used in small quantities, the accuracy of weighing is lost.

Furthermore, under the Fire Service Act, silver nitrate crystals are subject to regulations, and all manufacturing and handling facilities, storage, and transportation are subject to regulations.
Measures must be taken in accordance with laws regarding hazardous materials management, and a safe and efficient silver nitrate drug form is required.

The above considerations are generally required not only for silver nitrate but also for nitrates.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a safe and efficient drug form of nitrates, particularly silver nitrate, and a method for producing the drug form.

(Structure and efficiency of the invention) The object of the present invention is achieved by a method for producing nitrate briquettes characterized by dry compression molding using a raw material of fine nitrate particles, and a nitrate briquette produced by the method.

In an embodiment of the present invention, it is preferable to subject the raw material of nitrate fine particles to deaeration treatment prior to dry compression molding.

Further, when the present invention is applied to photographic silver nitrate, its effects are remarkable.

Next, the present invention will be explained using figures.

For mass production according to the present invention, a tabletting machine or a briquetting machine is useful. 1st
The figure shows a schematic diagram of a briquetting machine that can be used in the present invention.

1 is a hopper into which the raw material (fine particles) is input, 2 is a deaeration tank that removes air from the fine particle raw material and increases the yield of briquettes, 3
5 is a pair of high-pressure kneader rolls for performing high-pressure compression molding (hereinafter referred to as granulation), and 51 and 52 are a pair of high-pressure kneader rolls. Pockets 6 corresponding to the shape and size to be given to the briquettes are arranged on both roll surfaces so that the circumferential edges of the pockets match exactly at the pressure contact points. The depth and shape of the pocket bottom can be freely selected as long as the peripheries match.

The contact pressure is applied by a hydraulic system or the like, and is adjusted to provide a collapse strength suitable for the intended use of the briquettes. Further, if necessary for granulation, the temperature may be adjusted to an appropriate temperature.

Further, the surface layer for punching the pockets is preferably made of a material that is rigid enough to withstand the materialization of the raw material and the pressure, and is preferably replaceable.

As for the granulation conditions for photographic silver nitrate, the water content of the raw material for fine particles is preferably 0 to 1%, more preferably 0.1 to 0.8%. If it is less than 0.1%, it is difficult to reach it by centrifugal dehydration.
Also, fine powder is likely to be generated during handling. Moreover, if it exceeds 1%, the squeezed out water will adhere to the surface of the briquettes, causing undesirable situations such as caking between the briquettes and adhesion to the container wall.

The size of the raw material fine particles is preferably in the range of 0.1 to 3 mm, and a broad distribution within this range is convenient for closest packing and improves granulation properties.

In addition, the chemical form of briquettes is determined by taking into consideration the minimum effective numerical unit weight suitable for the usage mode, practically sufficient disintegration strength, large apparent specific gravity, small volume, and high dissolution rate. .

Powder generated by disintegration, rubbing, etc. causes caking and adhesion to container walls, so it is preferable that there is no powder at all, but mixing up to about 1Qwt% does not pose a problem in practice.

Table 1 below shows examples of granulation conditions for 309 silver nitrate briquettes with a diameter of 2.5 cm and the corresponding characteristics.

As mentioned above, the most suitable silver nitrate briquette chemical form is selected in consideration of various matters.

In addition, the silver nitrate briquette according to the present invention in the form of an amorphous lump is manufactured by Nippon Carlit Co., Ltd.; According to the evaluation results of the Hazard Evaluation Laboratory, the raw material fine particle silver nitrate was determined by a falling ball impact sensitivity test to have a falling ball weight of 1.4 g. During the exam, all
However, when the weight of the falling ball was 261g, all of the 10 tests resulted in an explosion, and it was classified as ``moderately dangerous.'' Also, according to the combustion test, the burning time was 22 seconds, making it ``highly dangerous.'' It is classified as a "Type 1 oxidized solid".

On the other hand, regarding silver nitrate briquettes, in the 50/60 iron tube detonation test, only the iron tube in the booster section was destroyed.
Since some sample remains, it is considered "non-explosive" and is rated as "hazardous". Also, in a 500g combustion test, it burned approximately 90 degrees. Although all of the wood powder was burned out by this combustion, it was confirmed that some silver nitrate remained. Therefore, in the 500g combustion test, it is determined that "combustion is interrupted."

Therefore, silver nitrate briquettes are in a "hazardous state" and are evaluated as a "non-hazardous material."

The above test method is introduced in the ``Danger Evaluation Test Method for Unstable Substances'' established by the above-mentioned Hazard Evaluation Laboratory, which is regulated in accordance with laws and regulations.

As described above, the silver nitrate briquettes prepared according to the present invention are as follows: (1) The danger disappears by granulation, and after granulation, the silver nitrate briquettes can be handled as general chemicals.

(2) By adopting the briquette form, handling properties are greatly improved, transportation, packaging, and supply operations are simplified, and automation, continuity, and quantification are facilitated.

(3) By selecting the briquette form, the dissolution rate can be reliably controlled with good reproducibility, and the process progress can be stabilized.

(4) There is no adhesion to the walls of containers or other vessels, and no formation of solidified lumps, reducing losses and reducing handling man-hours.

(5) Eliminates human injury and pollution of the working environment due to silver nitrate fine dust.

It has many advantages such as.

(Example) Next, examples will be shown and explained.

Large crystalline silver nitrate with good purity is precipitated by a conventional method, crushed into fine particles with a broad distribution in the range of 0.1 to 3+n+n, washed and centrifugally dehydrated to have a water content of 0.13vt.
%, and using a briquetting machine (briquette ■; manufactured by Shinto Kogyo Co., Ltd.) shown in Fig. 1, a diameter of 9 mm, 30
briquettes and sealed in a thick vinyl bag treated with a brown gas-impermeable laminate. In this state, no caking occurred when left in a bright room for 30 days. Moreover, there were no changes in physical properties, chemical properties, or purity, and furthermore, no problems occurred as silver nitrate for use in chemically extremely sensitive photographic materials.

The large crystalline silver nitrate was prepared according to the conventional form with a water content of 0.1.
A comparative sample containing 3 wt % of fine particles of 2 mm or less and sealed in the above-mentioned vinyl bag solidified in just 3 days.

Further, the risks of the samples of Examples and Comparative Examples were as described above.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a briquetting machine used in the present invention. 2... Deaeration tank, 4... Taber screw 5...
- High pressure kneader roll pair, 51 and 52... High pressure kneader roll, 6... Pocket R... Raw material, B... Briquette.

Claims (3)

[Claims] (1) Nitrate briquettes formed by dry compression molding from raw nitrate fine particles. (2) A method for producing nitrate briquettes, which comprises dry compression molding using a raw material of nitrate fine particles. (3) The method for producing nitrate briquettes according to claim 2, characterized in that in the production method, the raw material of nitrate fine particles is previously deaerated and subjected to dry compression molding.