CS253906B1 - Isolation method of the palladium from solutions in production and regeneration palladium catalysts - Google Patents

Abstract

The solution relates to a method of isolating palladium from solutions resulting from production and regeneration palladium catalysts; the palladium is precipitated continuously water-soluble 2-mercaptobenzothiazole salt a the resulting precipitate is subsequently separated known methods.

Description

The invention relates to a process for the isolation of palladium from solutions resulting from the production and regeneration of palladium catalysts containing said precious metal by the continuous precipitation of palladium with a water-soluble salt

2-mercaptobenzothiazole followed by separation of the resulting precipitate by known methods.

When handling palladium-containing solutions at a very low concentration, which arise in the production and regeneration of the palladium catalyst, respectively. In the treatment of wastewater from regeneration processes, it is necessary to isolate the palladium and return it to the process. Said dilute Pd solutions often have the character of wastes, the precious metal content of which does not allow them to be used as a waste metal. makes it extremely expensive. In the case of large amounts of soiled solutions, the choice of a suitable method for the isolation of the precious metal is very difficult.

Previous attempts to isolate palladium into a form suitable for further processing and recovery are based on the primary conversion of palladium-containing waste solutions into chloride solutions, or on the conversion of palladium into acid solutions. Attempts have also been made to isolate palladium from wastewater by chemisorption.

A disadvantage of these solutions is that the impurities, particulate matter and particulate matter present are complicated, respectively. prevent their application.

Converting palladium to a chloride solution requires further processing, similar to converting it into acids. This means that their direct application is not possible. In chemisorption, high demands are placed on the respective sorbent, which is destroyed by the presence of the components present, especially the particulate matter and its cost is also important. Further problems arise with displacement of the anchored phase, respectively. with further processing of the eluates.

In the case of precipitants, there is a problem with their selectivity.

It has now been found that the above-mentioned deficiencies are overcome by the process for the isolation of palladium from wastewater according to the invention, characterized in that palladium is continuously precipitated with a water-soluble salt of 2-mercaptobenzothiazole at pH less than 2.5 and subsequently precipitated. For separation it is advantageous to use flotation combined with filtration, respectively. by centrifugation of the flotation foam. After filtration, the filter cake (palladium foam) is burned with palladium concentrate.

The essence of the invention is that all or part of the process is carried out continuously.

Advantage of said method of palladium insulation is the use of flotation in particular, which makes it possible to reduce the demands on filtration operations, since it is sufficient to filter only the faded palladium foam. This process is particularly advantageous for large volumes of liquids and continuous process guidance.

The following examples illustrate but do not limit the scope of the invention.

Example 1

A palladium recovery solution with a residual Pd content of 29.1 mg / kg wastewater, with an iron content of 150 mg / kg wastewater having a pH = las of 0.2 kilograms / min, was precipitated continuously with ammonium salt of 2-mercaptobenzothiazole at a concentration of 8, 7% by weight with a foam of 2% by weight. The flow rate of the precipitant was 25 g per minute. After flotation, the palladium concentration in water dropped to 0.45 mg / kg, representing a yield of 98.45%. The palladium foam was found iron content of at least 10 ^"3 percent by weight. A two-chamber flotator with a chamber volume of 12 L was used for flotation.

Example 2

In a discontinuous arrangement, 1.6 cm ³ of 6.5% ammonium salt of 2-mercaptobenzothiazole ammonium salt was added to a 300 cm ³ electrolyte solution from Pd regeneration with a Pd content of 9.15 mg / L and a pH = 1. The suspension was filtered through a frit 84 after 15 min. In the filtrate, the Pd concentration was below the assay limit of 0.1 mg Pd / L. This represents a yield of 98.9%.

Example 3

A palladium recovery solution with a Pd content of 73.19 mg / kg wastewater at pH = 2, with a flow rate of 240 l / h, was continuously precipitated with ammonium salt of 2% mercaptobenzothiazole at a concentration of 1.56%. The precipitation flow rate was 9.32 l / h. After flotation and filtration, the concentration of Pd in water dropped to 0.62 mg / kg, representing a yield of 99.2%.

A four-chamber flotator with a chamber volume of 120 liters was used as a flotator to filter the floated filter press foam.

Claims (2)

A process for the isolation of palladium from solutions from the production and recovery of palladium catalysts comprising said precious metal, characterized in that palladium is precipitated with a water-soluble salt of 2-mercaptobenzothiazolysis at a pH of less than 2.5 and the resulting precipitate is subsequently separated. 2. A method according to claim 1, characterized in that all or part of the process is carried out continuously.