JPH09256083A - Method for manufacturing high purity silver and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and equipment for manufacturing high purity silver, capable of manufacturing high purity silver of >=99.9999wt.% (>=6N) purity in a state of ingot, by developing a new refining means capable of separating gold, palladium, lead, etc., which are difficult in perfect separation from silver by the conventional technique. SOLUTION: Electric silver of 99.99wt.% purity is put into a raw material crucible 5, and this raw material crucible 5 is fixed on a suction stand 9 disposed in the central part of a recovery mold 6. The raw material crucible 5 and the recovery mold 6 are sealed double by means of an external cylinder 3 and an internal cylinder 4 which are made of quartz. When the air inside the internal cylinder 4 is exhausted by an evacuation device 2 to regulate the degree of vacuum in the internal cylinder 4 to 0.01Pa and heating is performed at 1300 deg.C furnace temp., the silver in the raw material is evaporated temporarily and begins to condense gradually by contact with the inner surface of the internal cylinder 4 and then falls, in a granular state, into the recovery mold 6. By recovering this granular silver, the high purity silver of 6N purity can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a purity of 99.99 wt%.
The present invention relates to a method and an apparatus for producing high-purity silver having a purity of 99.9999 wt% or more from commercially available electric silver, shot silver, and ingot silver by vacuum distillation purification.

[0002]

2. Description of the Related Art In general, silver is used for recovering purified silver by electrolytic refining methods such as the Mobius method for recovering silver from a solution in which silver nitrate is dissolved, as well as for reducing and collecting from silver nitrate solution, zone refining method, or reelectrolysis. It is recovered by means such as a purification method.

Among them, in the electrolytic refining method by the above-mentioned Mobius method which is industrially used, it is general to scrape off needle-shaped or dendrite-shaped silver crystals deposited on a fixed cathode to obtain purified silver. According to JIS H2141, the first kind of silver metal is Ag 99.99% or more as a chemical component, Pb 0.001% or less as an impurity, Bi 0.001% or less, C
It is specified that u is 0.003% or less and Fe is 0.002% or less.

However, in this method, it is difficult to electrochemically completely separate silver from gold and palladium, and therefore, gold and palladium are separated by a combination of an ion exchange method and a chemical precipitation separation method. However, these methods have complicated control of electrolytic solution, and complicated liquid control process such as washing of deposited silver or treatment of washing waste liquid.

Also in the above-mentioned reduction and collection method, purified silver is obtained by chemically separating the impurities and then reducing the refined silver nitrate solution with a reducing agent. However, similar to the Meavius method, the liquid management process is complicated. There was

Further, even in the case of the zone refining method, there is a need for cutting after the refining and there is a risk of contamination.
Restrictions on the amount of processing during purification and reduction in purification yields were unavoidable.

In any case, when the refined silver refined by these conventional methods is used as an ingot, there is a problem of contamination due to mixing of impurities during casting. However, when it was made into an ingot, there was a great risk that the purity would deteriorate.

[0008]

As described above, by developing a novel refining means capable of separating gold, palladium, lead, etc., which was difficult to be completely separated from silver by the conventional technique, the purity of 99. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus capable of directly manufacturing 9999 wt% or more of high-purity silver in the form of an ingot.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve such problems, and found that impurities and silver can be separated by heating raw material silver under vacuum. Could be provided.

That is, the first aspect of the present invention is that sulfur, iron,
Copper, palladium, gold and lead contents are 0.5 each
Below 1 ppm, the total amount of impurities other than gas components is 1 ppm
It is a high-purity silver having a purity of 99.9999 wt% or more, which is less than 99%.

Secondly, the purity is 9 in which the contents of sulfur, iron, copper, palladium, gold and lead are each 0.5 ppm or less and the total amount of impurities other than gas components is less than 1 ppm.
A method for producing high-purity silver of 9.9999 wt% or more, which comprises vacuum distilling a silver raw material in a vacuum container at a temperature of 1050 ° C. or more and a vacuum degree of 0.1 Pa or less. Is.

A third aspect of the present invention is an apparatus for producing high-purity silver, which comprises a vacuum refining section and a heating section equipped with an electric furnace for heating the vacuum refining section as main components. Each is composed of a raw material crucible, a recovery mold, a trap, and a water-cooling flange that are detachably connected to each other, and the raw material crucible and the recovery mold are enclosed by a double cylinder made of a heat-resistant material. This is a device for producing pure silver.

[0013]

The high-purity silver refining apparatus of the present invention can have the structure shown in FIG. 1 as an example. For example, a raw material crucible 5, a recovery mold 6, a trap 8, and a water cooling flange 7 can be attached to and detached from the outer cylinder 3 so that the quartz outer cylinder 3 installed in the electric furnace 1 can be evacuated by a vacuum evacuation device 2. And a quartz inner cylinder 4 located on the upper surface of the raw material crucible.

In this case, the raw material silver (purity 99.99 wt%
(Amount of) is put into the raw material crucible 5 in an electric furnace at 1050 ° C.
Above, preferably in the temperature range of 1200 ℃ ~ 1350 ℃, the vacuum degree is 0.1 Pa or less, preferably 0.
If the pressure is controlled to 02 Pa or less, the raw material silver in the raw material crucible is heated and evaporated, and condensed on the upper surface of the quartz inner cylinder at the top to become refined granular silver.
And a collecting mold 6 connected to the bottom of the crucible.
Fall into

Among the impurities contained in the raw material silver, gold, copper, palladium, iron, etc., which have a lower vapor pressure than silver, remain in the raw material crucible 5 and, conversely, sulfur, sodium, calcium, lead having a high vapor pressure. Is condensed into the cooling trap 8 through the absorption holes provided at the bottom of the crucible by the vacuum exhaust device 2 without being condensed, and is cooled and solidified by the action of the water cooling flange 7.

In the present invention, since the shape of the recovery mold is set in advance to the shape of the mold used in the next step after the purification, it is not necessary to re-cast the refined silver as in the conventional method. Therefore, high-purity silver with less contamination can be manufactured in a single process without distinguishing the refining / casting process.

When the high-purity silver thus obtained was analyzed by a glow discharge mass spectrometer, sulfur, iron, copper,
Palladium, gold and lead are below 0.5ppm each,
Sodium, silicon, potassium, calcium, chromium,
The nickel content was 0.1 ppm or less, and the amount of impurities other than gas components was less than 1 ppm.

Therefore, in the present invention, the elements to be measured are Na, Si, S, K, Ca, Cr, Fe, Ni and C.
u, Pd, Au, and Pb were quantitatively analyzed by a glow discharge mass spectrometer, and the total of the obtained impurity contents was 1
The value obtained by subtracting from 00 wt% is 99.999.
Purity of 99.9999 wt% when 9 wt% or more
The above is defined as high-purity silver.

Hereinafter, the method of the present invention will be described in detail with reference to examples, but the method of the present invention is not limited thereto.

[0020]

Example 1 Using the manufacturing apparatus shown in FIG. 1, the desired high purity silver was obtained. First, 100 g of electric silver having a purity of 99.99 wt% was put into the raw material crucible 5, fixed on the suction table 9 installed in the central part of the recovery mold 6, and then charged into the electric furnace 1 as shown in FIG.

In this case, a quartz outer cylinder 3 and an inner cylinder 4 are provided on the upper surfaces of the raw material crucible 5 and the recovery mold 6, and the air inside the inner cylinder 4 is provided above the suction table 9 by the vacuum exhaust device 2. Is sucked out through a suction hole (not shown) provided in the inner cylinder 4
It has a structure that the inside of the is in a vacuum state.

After charging the raw crucible 5 into the electric furnace 1,
Evacuate with the vacuum exhaust device 2 and set the degree of vacuum in the inner cylinder 4 to 0.0
After refining to 1 Pa and keeping the furnace temperature constant at 1300 ° C. for 5 hours, the silver in the raw material once evaporated and then contacted the inner cylinder 4 surface on the raw crucible 5 and gradually began to condense and became a granular raw material. It dropped into a recovery mold 6 provided at the bottom of the crucible 5. 80g of this refined silver was recovered and its quality is shown in Table 1.
It was shown to.

On the other hand, those having a vapor pressure higher than that of silver were sucked in a gas state by the exhaust device, passed through the suction holes provided in the upper part of the suction table, and solidified on the cooling trap. When this solidified product was analyzed, it was found that the main components were all substances with high vapor pressure, such as sulfur, sodium, calcium, and lead. In addition, when the metal remaining in the raw crucible was also analyzed, it was found that the main component thereof was a substance having a low vapor pressure, such as gold, copper, palladium, or iron.

[0024]

[Table 1]

[0025]

Example 2 100 g of electric silver having a purity of 99.99 wt% was placed in the raw material crucible 5 and refined in the same manner as in Example 1 with the vacuum degree set to 0.01 Pa and the heating temperature set to 1200 ° C. to obtain 60 g of refined silver. It was The quality is also shown in Table 1.

[0026]

[Comparative Example 1] For comparison, an analytical value of purified silver obtained by electrolytically refining electro-silver having a purity of 99.99 wt% by the Mobius method currently used industrially and scraping off the silver crystals deposited on the cathode. Are also shown in Table 1.

[0027]

As described above, in place of complicated steps such as cleaning / electrolytic refining, reduction and collection, washing, drying, casting and post-treatment which are conventionally required, the manufacturing apparatus of the present invention having a simple structure is provided. By using it, a series of steps from refining to casting can be performed in one treatment. Furthermore, it is possible to separate gold and palladium, which were conventionally considered difficult to separate from silver, and the present invention is expected to contribute to the reduction of the production cost of high-purity silver.

[Brief description of drawings]

FIG. 1 is a schematic view showing the entire apparatus for producing high-purity silver of the present invention.

[Explanation of symbols]

 1 Electric Furnace 2 Vacuum Evacuation Device 3 Quartz Outer Cylinder 4 Quartz Inner Cylinder 5 Raw Material Crucible 6 Recovery Mold 7 Water Cooling Flange 8 Trap 9 Suction Stand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Yamauchi 1-2-8 Marunouchi, Chiyoda-ku, Tokyo Same as Mining Co., Ltd. (72) Inventor Minoru Nakayama 1-2-8 Marunouchi, Chiyoda-ku, Tokyo Within Wa Mining Co., Ltd.

Claims (3)

[Claims] 1. A purity of 99.99 in which the contents of sulfur, iron, copper, palladium, gold and lead are each 0.5 ppm or less and the total amount of impurities other than gas components is less than 1 ppm.
High-purity silver of 99 wt% or more. 2. Purity 99.99 in which the contents of sulfur, iron, copper, palladium, gold and lead are each 0.5 ppm or less and the total amount of impurities other than gas components is less than 1 ppm.
A method for producing high-purity silver of 99 wt% or more, which comprises subjecting a silver raw material to vacuum distillation in a vacuum container at a temperature of 1050 ° C. or more and a vacuum degree of 0.1 Pa or less. 3. An apparatus for producing high-purity silver, comprising a vacuum refining section and a heating section equipped with an electric furnace for heating the vacuum refining section as main components, wherein the vacuum refining sections are detachably connected to each other. An apparatus for producing high-purity silver, comprising a crucible for use, a recovery mold, a trap, and a water cooling flange, and the crucible for raw material and the recovery mold are enclosed by a double cylinder made of a heat-resistant material.