JPS616130A - Distillation method of ruthenium salt - Google Patents

Abstract

PURPOSE:To prevent sticking of RuO4 and to recover Ru efficiently in a short time by saturating water contg. extracted Ru with gaseous chlorine, decomposing generated hypochlorite by reducing pH of the liquid, and absorbing evaporated RuO4 by HCl. CONSTITUTION:Ru salt (or compd.) stripped off a metallic electrode or coating material contg. the Ru salt, etc. is impregnated with aq. alkali. After drying the impregnated material, a soluble Ru salt which is formed by heating and melting is extracted with pure water. The pure water soln. is fed to a distillation tower and saturated by blowing gaseous chlorine to form hypochlorite. The pH is reduced to 10-11 by adding HCl to the liq. The hypochlorite is decomposed violently, and the inside of the distillation tower is simultaneously converted to oxidizing atmosphere, and evaporated Ru is led to an absorption tower, where it is absorbed by HCl.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an anode for an electrolytic cell (metal electrode 1 used).
This invention relates to a method for distilling Ru salt produced by melting a coating in order to recover and reuse Ru or RU compounds used in catalysts, electronic parts, etc.

(Prior art and its problems) Recently, a metal electrode in which a substrate of a corrosion-resistant metal such as Ti, Zr, Ta, or Nb is coated with Ru or its compound, which has conductivity and corrosion resistance, has been used as an anode, and has excellent chlorine overvoltage characteristics. It is widely used due to its dimensional stability and the spread of the diaphragm method in the alkaline industry.

When such an electrode is used in an electrolytic cell, the wear rate of the electrode is low, or in order to maintain the best performance of the electrode, it is necessary to stop using the electrode and regenerate it before the performance deteriorates. It is necessary to use it effectively.

Furthermore, since Ru is particularly rare among platinum group elements, it is necessary to collect it from the electrode coating and reuse it.

To recover Ru from a coating containing or containing Ru or a Ru compound stripped from a metal electrode, the coating is melted to form a soluble Ru salt, and then the Ru salt is It is necessary to volatilize and produce highly pure Ru.

Conventionally, to distill Ru salt, two methods have been used: one method is to continue blowing chlorine gas into an alkaline solution, lower the pH of the solution as an oxidizing agent is supplied, and distill the Ru salt under close pressure. There is a method of volatilizing Rub by adding an oxidizing agent as an acid.

However, in the former method, chlorine gas is injected by bubbling, so chlorine gas cannot be used effectively.

In addition, unabsorbed chlorine gas must be treated as a pollution. Furthermore, if the alkali is strong, it will take time for the pH to drop, leading to problems such as a longer retention time. In the latter method, some RuO4 decomposes during the distillation and deposits on the inner wall of the container.Additionally, oxidizing agents other than chlorine gas cannot sufficiently oxidize Ru compounds, resulting in black precipitates of RuO2 in the liquid. , there are problems such as a decrease in the Ru recovery rate.

(Object of the invention) The present invention was made in view of the problems of the conventional method described above.
Chlorine gas can be used effectively, the amount of chlorine gas used for pollution treatment can be extremely reduced, and even if the alkali is strong, the distillation time can be shortened. Furthermore, Ru O4 does not adhere to the inner wall of the container during low temperatures, and Ru salt can be sufficiently contained. The object of the present invention is to provide a method for distilling Ru salt, which can improve the recovery rate of Ru by oxidizing the Ru salt.

(Structure of the Invention) The Ru salt distillation method of the present invention involves blowing chlorine gas into a liquid extracted from Ru salt with water to saturate it, producing hypochlorite in the extracted liquid, and then extracting the Ru salt with water. The method is characterized in that an acid is introduced into the solution to lower the pH to decompose the hypochlorite and volatilize RuO4, and then the volatilized RuO4 is absorbed into hydrochloric acid.

(Example) An example of the Ru salt distillation method of the present invention will be described in the case of a soluble Ru salt produced from RuO2 powder. First, to explain the production of the soluble Ru salt, 85
%K O) 180g and KNO320g in 300m of pure water
This alkaline water/8I #l and 10 g of RuO2 powder exfoliated from the metal electrode were mixed and stirred in a nickel crucible to allow the aqueous alkali solution to permeate the entire RuO2 powder. Put it in a dryer and dry it at 140'C for 6 hours to remove moisture and obtain a dried product with powder particles attached.This dried product was preheated to 800'C. Place the crucible in a previously prepared electric furnace and heat for 1 hour.
u salt was obtained.

However, to explain the method of distilling this soluble Ru salt, first extract the Ru salt with 200 m/min of pure water, put this extracted liquid into the distillation column of the distillation apparatus, and add chlorine gas to the extracted liquid at 200 mβ/min for 10 min. It was saturated by bubbling for a minute. Then I started bubbling the distillation equipment. At this time, the extract was still strongly alkaline, and hypochlorite was produced in the solution. Next, add 36% I-I CI 30m to the extract.
When the pH was lowered by adding l, PH = 10-11
The reaction becomes intense near the plant, and RuO4 begins to volatilize, and this volatilized RuO4 enters the mist absorption tower heated to 70°C containing pure water, passes through the pure water, and is absorbed by the mist gas. It became RuO4, entered the Ru absorption tower containing hydrochloric acid, and began to be absorbed by the hydrochloric acid. In the distillation column, Ru
At the same time as O, or 1118 begins to be emitted, the hypochlorite in the extract begins to decompose, and this gas has oxidizing power.
In order to create an oxidizing atmosphere inside the distillation column and mist absorption column, Ru
O4 was reliably transported without being reduced and attached to the inner wall of the container. Continue to add 35 m I of 36% HCI into the retention tower.
! When the extract was lowered to around pH-7, K2
RuOa is mostly oxidized, 1! ! The mist containing impurities is absorbed in the mist absorption tower and becomes clean RuO.
4 and was absorbed by the hydrochloric acid in the Ru absorption tower. Therefore, we stopped introducing 36% HCI into the distillation column, continued bubbling for a while, oxidized and volatilized the remaining 2RuO4, dissolved and absorbed the mist in the mist absorption column, and converted it into Ru Oa into the Ru absorption column. Absorbed in hydrochloric acid. When the extract becomes near neutral, distill it while blowing chlorine gas into it.

Bubbling oxidizes 2Ru04 more completely,
llli is emitted and carried away.

The recovery rate of Ru absorbed in hydrochloric acid in this way was 99%, which is extremely efficient.

Another example of the Ru salt distillation method of the present invention is Ti02-R
The case of a soluble Ru salt produced from uO2 powder will be explained. First, to explain the production of the soluble Ru salt, 80 g of 85% KOH and 320 g of KNO are dissolved in 150 ml of pure water, and this aqueous alkali solution and Ti02
-4.0g of RuO2 powder (containing about 11% Ru) were mixed and stirred in a nickel crucible, and TiO2Ru
02 Powder was soaked in the aqueous alkali solution, and the stirred mixture was placed in a dryer with the jar at 140℃, 8
Dry for a few hours to evaporate the moisture to obtain a dried product with powders attached to each other.The dried product is placed in an electric furnace that has been preheated to 500'C and heated for 1 hour. A soluble Ru salt mixed with TiO2 in a deposited state was obtained.

However, to explain the method of distilling the soluble Ru salt mixed with TiO2, first, the Ru salt is extracted with 400 ml of pure water, and the extracted liquid and precipitated TiO are put together into a distillation column of a distillation apparatus. Add chlorine gas to the extract for 20 minutes.
0ml! /min for 15 minutes to achieve saturation. Then I started bubbling the distillation equipment. The extract at this time was still strongly alkaline, and hypochlorite was produced in the solution. Next, add 1155ml of 20% 6NHC to the extract.
When the PH was lowered by adding 200 ml of Ru, the reaction became intense around PH = 10 to 11, and RuO4 began to volatilize. The mist passes through pure water and is melted and absorbed to become Ru Q 4, which enters the Ru absorption tower containing hydrochloric acid and begins to be absorbed by the hydrochloric acid. At the same time as Ru Oa begins to volatilize in the distillation column, the hypochlorite in the extract begins to decompose, and this gas has oxidizing power.

In order to create an oxidizing atmosphere inside the mist absorption tower, RuO4 was reliably transported without being reduced and attached to the inner wall of the container.

178 m of 20% 6 N HCl was then added to the distillation column.
When the extract was lowered to PH=7 (=J), most of the K2RuO was oxidized and volatilized, and the mist was absorbed in the mist absorption tower, becoming Rub, and flowing into the Ru absorption tower. was absorbed into the hydrochloric acid. Then, white T' i 02 was precipitated in the distillation column.
Stop adding %6 N I-I CI and continue bubbling for a while to reduce the amount of 2 Rub4 remaining in the distillation column.
was oxidized and volatilized, fgM of mist was removed in a mist absorption tower, and the Ru Oa was absorbed into hydrochloric acid in the Ru absorption tower.

The recovery rate of Ru absorbed in hydrochloric acid in this way was 99.5%.
It is extremely efficient.

As shown in each of the above examples, Ru absorbed in hydrochloric acid is then recovered and purified as H2RuCia.

(Effect of the invention) As can be seen from the above explanation, the Ru salt distillation method of the present invention is as follows:
Ru salt is extracted with water, chlorine gas is blown into the solution to saturate it, hypochlorite is produced in the extract, and then acid is added to the extract to lower the P I-1 and the extract is Since the hypochlorite in the salt is decomposed and Rub4 is volatilized, and the volatilized Rub is then absorbed into hydrochloric acid, the chlorine gas can be effectively used without being wasted, and the chlorine gas can be used to treat pollution. can be extremely reduced. In addition, if the alkali is strong and the pH cannot be lowered by just blowing in chlorine gas, the pH can be lowered quickly by adding acid, which shortens the time for Ru salts to start retaining, and eventually R
The distillation time for u-salt can be significantly shortened. Furthermore, Ru O4
At the same time that RuO4 begins to volatilize, the chlorate decomposes and creates an oxidizing atmosphere, so that RuO4 is reliably transported without adhering to the inner wall of the apparatus. In addition, Rub4 is sufficiently oxidized by blowing chlorine gas into the distillation column, decomposing the generated hypochlorite, and adding acid, and no black precipitate occurs, so RuO4 is completely removed. It can be distilled to R
There are excellent effects such as a significant improvement in the recovery rate of u to 99% or more.

Claims (1)

[Claims] Ru salt is extracted with water, chlorine gas is blown into the solution to saturate it, hypochlorite is produced in the extract, and then an acid is added to the extract to lower the pH to remove the hypochlorite. is decomposed and RuO_4 is volatilized, and then the volatilized RuO_4
A method for distilling Ru salt, which comprises absorbing Ru salt in hydrochloric acid.