JP2556883B2 - Rhodium recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention relates to a method for recovering rhodium, in which rhodium is precipitated and separated from an acidic solution containing rhodium.

(Conventional technology and its problems) Conventionally, as a method for separating and separating rhodium from an acidic solution containing rhodium, the rhodium hydroxide was precipitated as rhodium hydroxide,
A method of separating by filtration is generally used.

However, since rhodium hydroxide has small particles, a coagulation operation is required, and heating and aging have been performed.However, when the amount of liquid is large, the equipment becomes large and complicated, and aging takes time, resulting in filtration and separation. However, there is a drawback that it takes a long time and the collection cost becomes high.

Furthermore, when the acidic solution containing rhodium contains a large amount of a salt such as ammonium, it becomes difficult to form a precipitate of rhodium and agglomerate sufficiently by the above method,
There was a problem that the recovery rate of rhodium was low.

(Object of the Invention) The present invention has been made to solve the above-mentioned drawbacks of the conventional method, and provides a method for precipitating and separating rhodium with a high recovery rate in a short time with a simple operation. It is intended.

(Means for Solving the Problems) The present invention relates to a method of precipitating and separating rhodium from an acidic solution containing rhodium, which is made alkaline by adding an alkali hydroxide and then adding zinc chloride and / or aluminum chloride. It is a method for recovering rhodium, which comprises neutralizing and precipitating to form a precipitate, which is then separated.

An alkaline solution is added to an acidic solution containing rhodium (hereinafter referred to as “rhodium recovery solution”) with stirring to make it alkaline.

Alkali hydroxide used here is sodium hydroxide,
Potassium hydroxide, calcium hydroxide, barium hydroxide, etc., but inexpensive and easily available sodium hydroxide,
More preferably, it is used as an aqueous solution in order to carry out the reaction rapidly and uniformly.

PH when adding alkali hydroxide to make it alkaline is 10
The pH is adjusted to -12, more preferably PH 10.5 to 11.5.

Then, zinc chloride and / or aluminum chloride is added to neutralize to PH6-8 to form a precipitate.

The zinc chloride and / or aluminum chloride used here is more preferably added as an aqueous solution, because when added in the form of a crystal, a hydroxide is formed on the surface of the crystal and the reaction is delayed.

The pH of 6-8 is the most stable rhodium hydroxide formed as a precipitate. If the pH is higher than 8, it becomes a complex salt and the precipitate is hard to form. If it is lower than PH6, the precipitate dissolves. This is because it is easier to do.

The reason for adding the above zinc chloride and / or aluminum chloride is that the chloride of the metal becomes a hydroxide, which has the function of coagulating and coprecipitating fine rhodium hydroxide. This is because the range is stable over a wide range and is a metal that is easily separated in the purification of rhodium after separation as a precipitate.

Note that magnesium chloride, iron chloride, indium chloride, or the like can be used as the other metal chloride.

Further, in the operation of the present invention, in order to recover the rhodium precipitate at a higher recovery rate, it may be carried out while oxidizing the rhodium ion, and the method may be a method using a general oxidizing gas or an oxidizing agent.

Further, when the precipitation of rhodium is insufficient due to the type of salt contained in the rhodium recovery solution, the object can be achieved by repeating the method of the present invention.

Example 1 A 2N-hydrochloric acid solution 2 containing 2 g / rhodium was placed in a 5 beaker and heated to 60 ° C., and 400 g / sodium hydroxide was added dropwise to obtain PH11.5.

Then, add zinc chloride 50g / solution to pH 7.0,
After continuing stirring for 1 minute, the precipitate was separated by filtration.

When rhodium in the filtrate was analyzed, it was 0.2 mg / filtrate and the filtrate was 4. Therefore, 0.8 mg of rhodium remained in the solution, and the recovery rate was 99.9% or more.

Examples 2 to 8 In order to neutralize the kind of the solution with the acidic solution containing 2 g / rhodium as shown in the left table below, the kind of alkali hydroxide and the PH when alkalinized as shown in the middle section The types of chloride added and PH were set to the conditions as shown in the right section, and the results of Examples 5 and 6 were obtained.
Was oxidized with hypozinc acid, and in Examples 7 and 8 a precipitate was formed while being oxidized with chlorine gas. After separation by filtration, rhodium in the filtrate was analyzed. The results were as follows.

Conventional example-1 Put 2N-hydrochloric acid solution 2 containing 2g / rhodium in 5 beakers, add sodium hydroxide 400g / solution dropwise, adjust pH to 8, aging at 60 ° C for 4 hours, cooling to room temperature, When separated by filtration and analyzed for rhodium in the filtrate, rhodium was 120 mg / and the filtrate was 3
With 360 mg remaining, the recovery rate of rhodium is 9
It was 1.0%.

Conventional example 2 2N containing 2g / of rhodium and 200g / of ammonium chloride
-Put hydrochloric acid solution 2 in 5 beakers and add sodium hydroxide
400g / solution was added dropwise, pH was adjusted to 7.5, aged at 60 ° C for 4 hours, cooled to room temperature, filtered and separated, and rhodium in the filtrate was analyzed. Rhodium was 180mg / This means that 540 mg of rhodium remained, and the recovery rate of rhodium was 86.5%.

(Effect of the invention) The present invention is a method of precipitating and separating rhodium from an acidic solution containing rhodium, which is made alkaline by adding alkali hydroxide, and then neutralizing by adding zinc chloride and / or aluminum chloride. The disadvantage of the conventional method is that it is a simple method of forming and separating a precipitate, which requires a long aging time to agglomerate the precipitate of rhodium and a long filtration time. It is possible to solve both of the drawbacks that the recovery rate is low due to the influence, which enhances production efficiency and is valuable.

Claims (1)

(57) [Claims] 1. A method of precipitating and separating rhodium from an acidic solution containing rhodium, which is made alkaline by adding alkali hydroxide and then neutralizing by adding zinc chloride and / or aluminum chloride to form a precipitate. A method for recovering rhodium, characterized in that