JP2526257B2 - Crucible for producing Pt, Pd-based granular noble metal particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crucible for producing a noble metal granular mass such as Pt, Pt alloy, Pd, and Pd alloy.

(Prior art and its problems) Conventionally, in order to produce the above-mentioned noble metal granular lump, first, the noble metal ingot is melted in a melting furnace, this molten metal is transferred to a holding furnace and remelted, and the molten metal is continuously fed from a nozzle at the bottom. It was made to fall into water and made a noble metal granular mass. 2 in this method
Since there are times of remelting and transfer of molten metal, it takes time and effort,
Moreover, there was a problem in that when the molten metal was transferred, it was oxidized.

In order to prevent the above-mentioned oxidation, a deoxidizer is added to the precious metal melt in the holding furnace, but the precious metal melt is contaminated with the deoxidizer. Furthermore, since the melting furnace and the holding furnace are made of zirconia, they have high fire resistance,
Since the thermal shock resistance is low, the nozzle of the holding furnace tends to be damaged.

For this reason, a noble metal ingot is melted in a layered zirconia crucible, and a molten metal is continuously dropped from a nozzle at the bottom into water to form a noble metal granular mass.

However, even this layered zirconia crucible was insufficient for thermal shock, and the damage to the nozzle could not be prevented. Further, since the nozzle hole is straight and the length is longer than the inner diameter, there is a problem that the noble metal melt having a high melting point is solidified while flowing down the nozzle and is clogged so that it cannot flow down.

(Object of the Invention) The present invention has been made to solve the above problems,
It has fire resistance and excellent thermal shock resistance, and can reliably prevent nozzle damage as well as the crucible body.
Moreover, it is an object of the present invention to provide a Pt, Pd-based noble metal granular agglomerate crucible capable of continuously flowing a molten noble metal without clogging of a nozzle.

(Means for Solving Problems) A crucible for producing Pt and Pd-based noble metal granular lumps according to the present invention for solving the above problems covers an inner crucible made of zirconia with an outer crucible made of alumina and silicon oxide. There is no double crucible, the inner part of the double crucible has an inner diameter of 2 to 7 mm, a straight part with a length of 3 to 6 mm and an expanded inner diameter of 7.3 to 16.2 mm, and a tapered part with a length of 10 to 17 mm. It is characterized in that a nozzle having a nozzle hole is formed and the nozzle is covered with an outer crucible.

The reason why the inner diameter of the straight portion of the nozzle hole is 2 to 7 mm in the crucible of the present invention is that if the inner diameter is less than 2 mm, the molten metal is likely to solidify, and if it exceeds 7 mm, the molten metal falls off too much. The reason for the length of 3 to 6 mm is that if the length is less than 3 mm, the molten metal will not flow down continuously, but will drop intermittently to leak,
This is because if it exceeds m, the molten metal is likely to solidify during the flow. The above-mentioned dimensions are optimal because the tapered portion improves the cutting of the molten metal.

(Operation) The Pt, Pd-based noble metal granular lump producing crucible of the present invention configured as described above has a high fire resistance in the inner crucible, and the outer crucible covered therewith has a large thermal shock resistance. The inner crucible with low impact resistance is reliably protected. Further, since the nozzle provided integrally with the inner crucible on the bottom of the double crucible is covered with the outer crucible, the nozzle having small thermal shock resistance is surely protected. Therefore, when the precious metal ingot is melted in the double crucible and the molten metal is continuously dropped into the water from the nozzle at the bottom to form precious metal granular lumps, the nozzle as well as the inner crucible is not damaged. Also, because the nozzle hole of the nozzle consists of a straight part and a tapered part,
Unlike the case of a nozzle hole consisting of only a long straight part, it does not solidify and clog during the flow of molten metal, and even if it solidifies in a short straight part, it will be heated by the heat of the molten metal in the double crucible. It melts again and continuously falls into water, so that a noble metal granular mass can be smoothly produced.

(Example) An example of a crucible for producing a Pt, Pd-based noble metal granular lump of the present invention will be described with reference to the drawing. As shown in FIG.
The inner crucible 1 made of zirconia with m, depth 216 mm, thickness 8 mm and bottom R30 mm is covered with the outer crucible 2 made of alumina and silicon oxide with inner diameter 78 mm, depth 217 mm, thickness 8 mm and bottom R39 mm. No crucible, Nozzle hole 4 with straight part 4a with inner diameter 4mm, length 5mm integrated with inner crucible 1 at the bottom of this double crucible and expansion inner diameter 13.1mm, length 17mm, taper part 4b with expansion angle Forming a nozzle 5 having a bottom portion of the outer crucible 2.

The stamp material 6 is filled between the outer peripheral surface of the inner crucible 1 and the inner peripheral surface of the outer crucible 2.

In order to produce a Pt / Pd-based noble metal granular ingot by the Pt / Pd-based noble metal granular ingot producing crucible 7 thus constructed, the Pt / Pd-based noble metal granular ingot is set in the high frequency induction heating device 8 as shown in FIG. 750 mm diameter concentric with the nozzle 5 at a distance of 500 mm below
After arranging a water tank 9 with a depth of 2500 mm, put 3 kg of P in the crucible 7.
The d ingot is put and the high frequency induction device 8 is operated to melt the Pd ingot in the crucible 7. When the Pd ingot is completely melted, the Pt molten metal continuously drops from the nozzle 5 at the bottom into the water in the water tank 9 to form Pd granular lumps having a diameter of 4 mm or less.

In the production of this Pd granular mass, the inner crucible 1 having high fire resistance but low thermal shock resistance is covered with the outer crucible 2 having high thermal shock resistance, and the nozzle 5 integrated with the inner crucible 1 is the outer crucible 2. Since the inner crucible 1 and the nozzle 5 are protected by being covered by the bottom of the, the nozzle 5 as well as the inner crucible 1 is not damaged by thermal shock. Also, the straight portion where the nozzle hole 4 of the nozzle 5 is short
Since it consists of 4a and a long taper portion 4b, the molten metal does not solidify and clog during flowing down the short straight portion 4a, and even if it solidifies in the short straight portion 4a, it remains in the double crucible. Since it is melted again by the heat of the molten metal and continuously falls into water, it is possible to smoothly form Pd granular lumps.

(Effect of the invention) As can be seen from the above description, the crucible for producing Pt, Pd-based noble metal granular lumps of the present invention melts Pt, Pd-based noble metal by high frequency induction heating, and the molten metal is continuously dropped from the nozzle into the water tank. When the granular mass is formed by the above, the crucible is surely prevented from damage to the main body and the nozzle due to thermal shock. Further, Pt of the present invention,
The crucible for the production of Pd-based granular noble metal particles is a molten metal in the crucible that does not solidify and clog when the molten precious metal flows down the straight portion of the nozzle hole, even if it solidifies in the short straight portion. Since it is melted again by the heat of and falls into water continuously, the noble metal granular lumps can be made smoothly, the efficiency is improved, and industrial mass production is possible.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a crucible for producing Pt and Pd-based noble metal granular lumps of the present invention, and FIG. 2 shows a state in which the crucible is set in a high frequency induction heating device to produce granular lumps. FIG.

Claims (1)

(57) [Claims] 1. An inner crucible made of zirconia is covered with an outer crucible made of alumina and silicon oxide to form a double crucible, and an inner diameter 2 integral with the inner crucible is formed at the bottom of the double crucible.
~ 7mm straight length 3 ~ 6mm and expanded inner diameter 7.3 ~ 16.
A crucible for producing a Pt, Pd-based noble metal granular lump, characterized in that a nozzle having a nozzle hole having a tapered portion of 2 mm and a length of 10 to 17 mm is formed and the nozzle is covered with an outer crucible.