JPH02271926A - Liquefaction of iridium - Google Patents

Abstract

PURPOSE:To improve the efficiency of chlorination and the liquefaction rate of Ir compd. produced by chlorination by subjecting a Mn-Ir alloy the Ir content of which is controlled to <=30wt.% to leaching with acid and then chlorinating the obtd. Ir black. CONSTITUTION:The Ir-Mn alloy is controlled to have <=30wt.% Ir. This alloy is subjected to leaching of Mn with acid (hydrochloric acid, sulfuric acid or nitric acid) to obtain Ir black. The Ir black is mixed with chloride (NaCl, KCl, BaCl2), chlorinated with Cl gas by heating and then extracted with water.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for liquefying iridium.

(Prior art and its problems) Iridium has excellent chemical resistance and is hardly dissolved in ordinary acids and alkalis, as well as aqua regia and hydrochloric acid-chlorine.

Therefore, an alloy of iridium and zinc (80 to 90 wt%) was alloyed at 800°C to 850°C for 2.5 to 3 hours, with a salt coating on the surface to a thickness of 20 to 30 [llff1], with occasional stirring. Dissolve zinc with hydrochloric acid, etc. to obtain iridium black.

Next, a mixed salt of sodium hydroxide and sodium peroxide or potassium nitrate and the above iridium black were mixed at 800%
Iridium was converted into iridium oxide by alkali melting at around °C and dissolving the salt with water, followed by filtration and separation, followed by dissolving in hydrochloric acid or aqua regia.

However, when alloying iridium and zinc, unless the iridium is made into a fine powder or thin plate, alloying takes time, and the zinc must be coated with salt to prevent it from oxidizing during melting. There were drawbacks such as.

Furthermore, when iridium black is melted with an alkali and the salt is dissolved in water, some of the iridium is dissolved in the aqueous solution, so there is an economic disadvantage in recovering and purifying the iridium.

(Object of the Invention) The present invention was made to solve the above drawbacks, and an object of the present invention is to provide a method for liquefying iridium by chlorinating powder and bulk of iridium metal and liquefying the same by water extraction.

(Means for Solving the Problems) The present invention provides a method for liquefying iridium, including a first step of alloying iridium with manganese at a content of 30% or less, and an alloy of iridium and manganese. a second step of leaching with acid to obtain iridium black; a third step of mixing the iridium black with a chloride salt and chlorinating the iridium with chlorine gas under heating; This is a method for liquefying iridium characterized by comprising a fourth step of extracting iridium with water.

The reason for alloying iridium and manganese is that iridium and manganese are easy to alloy, and when they are alloyed and leached with acid, the leaching rate is faster than that of other metals such as zinc, and the resulting iridium black is fine and has a small surface area. This is because it is extremely large and can be easily mixed with a chloride salt when carrying out a chlorination reaction, making it possible to increase the reaction activity.

The reason why the alloy proportion of iridium is set to 30 wt% or less is that when the proportion of iridium is high, it exhibits properties similar to bulk iridium and cannot be leached with acid, and even when the proportion of iridium is low, the proportion of iridium is 30 wt% or less. Q
If it exceeds wt%, acid leaching becomes difficult or takes a long time.

The appropriate type of acid used for leaching is mineral acid, which is often used industrially, such as hydrochloric acid, sulfuric acid, or nitric acid.There are no particular limitations on the acid concentration, but it is important to control heat generation and hydrogen generation during acid leaching. It is desirable that the acid is within a range where the above-mentioned acids can be dissolved, and it is better not to use a mixture of the above acids since they may dissolve a small amount of iridium black.

The reason why iridium liquefies due to chlorination is that a soluble complex salt is formed by the chlorination reaction between chlorine gas and chloride salt as described below.

Ir+2NaCβ+2CL=Na21rCf.

Ir+2KCj! +2cfz = 2I rCj
! sI r+Bacj! 2+2(:i!z =Ba I
rClg These complex salts are easily soluble in water.

The chloride salt required for the above chlorination is chloride) IJum,
Typical ones such as potassium chloride and barium chloride may be used, and the required amount of chloride salt for iridium black is chloride per 1 mole of iridium) IJum, potassium chloride is 2 moles, and barium chloride is 1 mole. Although it is a mole,
In order to economically promote the chlorination reaction, it is recommended to use 1.2 to 2 times the stoichiometric amount.

The reaction temperature for chlorination is preferably 500°C to 900°C, but if the temperature is too high, the chloride salt will melt, reducing contact between gas and liquid, and gas and solid, and slowing down the chlorination reaction.

Furthermore, after the chlorination reaction, the reactants must be taken out after cooling.

This is because if a chlorinated iridium complex salt is removed from a chlorine gas atmosphere at a high temperature, iridium black or iridium oxide may be generated again due to thermal decomposition.

The chlorinated iridium complex is then extracted with water.

At this time, since chloride salts involve an endothermic reaction, water extraction becomes more effective when hot water is used.

Examples of the present invention will be described below, but the examples are not intended to limit the present invention.

(Example 1) Iridium metal (30mmX98.5mmX1.5mm
t) Mix 100g with 550g of manganese flakes and place in a crucible (made of alumina, diameter 60mm, height 150mm, thickness 5f).
Iridium l
An alloy ingot containing 5 wt% manganese and 85 wt% manganese was obtained.

The above alloy ingot was heated to 6N-HCj in a glass speaker.
! IOI! was added and leached for 3 hours at a liquid temperature of 45°C, manganese was dissolved to obtain iridium black, the iridium black was filtered, washed with warm water, and then dried at 60°C for 12 hours. Iridium in the solution in which manganese was dissolved in 6N-HCf was analyzed using an ICP analyzer to confirm that it was not detected.

Next, the dried iridium black was mixed with 100 g of sodium chloride and placed in a quartz boat, and the quartz boat was placed in a quartz tube loaded in a horizontal tubular electric furnace and chlorinated at 600°C for 2 hours in a chlorine stream. After cooling by supplying chlorine gas and nitrogen gas, the quartz boat was taken out.

Iridium black, which is chlorinated by mixing it with sodium chloride, is 21! Iridium in the aqueous solution extracted with water was analyzed and found to be 46g/I! The concentration was

From the above results, the liquefaction rate was 92%.

(Example 2) Iridium (10++
+ m x 89 mm x 5 mmt) was mixed and dissolved with 230 g of manganese flakes to obtain an alloy ingot containing 30 wt% iridium and 70 wt% mancali.

The above alloy ingot was heated to 6N-H2S in a glass speaker.
O
It was dried at t' for 12 hours.

Iridium in the solution in which manganese was dissolved in 6N-H, SO, was analyzed using an ICP analyzer to confirm that it was not detected.

Next, the dried iridium black was chlorinated in the same manner as in Example 1, and the iridium in the aqueous solution extracted with water in No. 21 was analyzed and found to have a concentration of 43 g/l.

From the above results, the liquefaction rate was 86%.

(Comparative Example 1) 100 g of iridium with a particle size of 5 to 20 μm and 100 g of sodium chloride were mixed, chlorinated in the same manner as in Example 1, extracted with water, and analyzed for iridium in the aqueous solution.2
1g/I! Met.

From this result, the liquefaction rate was 42%.

(Comparative Example 2) Using the same high-frequency melting method as in Example 1, iridium (30n
+mx98.5mmx1.5mmt) Mix 100g with 186g of manganese flakes and dissolve to make iridium 35w.
An alloy ingot containing 65 wt% of manganese and 65 wt% of manganese was obtained.

Thereafter, acid leaching was carried out in the same manner as in Example 1, and it took 30 hours for complete leaching.

Further, in the same manner as in Example 1, iridium black was chlorinated and then extracted with water. Iridium in the aqueous solution obtained was analyzed and found to be 36 g/ji! Met.

From this result, the liquefaction rate was 72%.

(Example 3) Iridium 15wt% obtained by the same operation as Example 1
Iridium black obtained by acid leaching, filtering, washing, and drying an alloy ingot containing 85 wt% manganese in the same manner as in Example 1 was mixed with 150 g of barium chloride and heated at 800°C in a chlorine stream in the same apparatus as in Example 1. After chlorination for 2 hours,
After cooling in a stream of chlorine gas and nitrogen gas in the same manner as in Example 1, the iridium in the aqueous solution obtained by extracting chlorinated iridium black with water of 31 was analyzed.29
g/l.

From this result, the liquefaction rate was 87%.

(Conventional example) Iridium (30mm x 98.5mm x 1.5
mmt) was mixed with 550 g of zinc, placed in a crucible (made of alumina, diameter 60 mm, height 150 mm, thickness 5 mm), covered with 30 mm of common salt, melted in an electric furnace, and after 1 hour cast in a copper mold to combine iridium and zinc. obtained alloy ingots.

The above alloy ingot was mixed with 6N-HCl in a glass speaker.
l 0 I! was added and heated to leached at a liquid temperature of 60 tt for 6 hours to dissolve the zinc to form iridium black, which was filtered and washed with warm water. 6N- above
When m2 of iridium in a solution of zinc dissolved in HCf was analyzed using an ICP analyzer, no detection was found.

Next, add iridium black to 300% sodium hydroxide.
g and 300 g of sodium peroxide were mixed, placed in a nickel crucible, and melted with alkali at 800°C for 1 hour in an electric furnace.The alkali melt was extracted with 51 water and filtered to analyze iridium in the aqueous solution. Tokoro 0. Ig/
The concentration was f.

The precipitate obtained by the above filtration was dissolved in hydrochloric acid to obtain a solution 3j2 having a concentration of 12 g/j2 of iridium.

From the above results, the liquefaction rate was 36%, but iridium was separated and liquefied in the aqueous solution extracted with water and the solution dissolved in hydrochloric acid.

(Effects of the Invention) As is clear from the above explanation, the method for liquefying iridium metal according to the present invention involves alloying iridium with manganese in a proportion of 30 wt% or less, and then leaching this iridium and manganese alloy with acid. Fine iridium black with a large surface area can be obtained, and this iridium black can be efficiently chlorinated with chloride salt and chlorine gas, and can be liquefied by water extraction, so it can be recovered and purified or used to produce iridium compounds. It is extremely effective in doing so.

Claims (1)

[Claims] 1. A method for liquefying iridium, which includes a first step of alloying iridium with manganese at a content of 30% by weight or less, and a second step of leaching the iridium and manganese alloy with acid to obtain iridium black. 2, a third step of mixing the iridium black with a chloride salt and chlorinating the iridium with chlorine gas under heating, and a fourth step of extracting the chlorinated iridium with water. A method for liquefying iridium, characterized by: