System and Method for Recovering Catalytic Precious Metal from Aqueous Galvanic Processing Solution

Abstract

A system is provided for recovering catalytic precious metals from aqueous galvanic processing solutions. The system comprises at least one holding tank, and at least one filtration unit, wherein the holding tank holds the galvanic processing solution and the filtration unit comprises ultrafiltration means and wherein the filtration unit is in hydraulic connection with the holding tank. The filtration unit is capable of providing a permeate stream having a reduced concentration of catalytic precious metal relative to the feed of the filtration unit and a concentrate stream with increased concentration of catalytic precious metal relative to the feed of the filtration unit. The system comprises at least one heat-exchanger hydraulically arranged between the holding tank and the filtration unit, being capable to limit the average temperature TRI of the aqueous galvanic processing solution to ≤50° C., preferably ≤45° C., more preferably ≤40° C. prior to entering the filtration unit.

Description

FIELD OF THE INVENTION[0001]The invention generally relates to a system and method for recovering catalytic precious metal from aqueous galvanic processing solutions.BACKGROUND OF THE INVENTION[0002]Electroless plating in general refers to the chemical deposition of a metal on a conductive, non-conductive, or semi-conductive substrate in the absence of an external electric source. Electroless deposition is used for many purposes, for example, in the manufacture of printed circuit boards where an electroless metal, often copper, is deposited on a dielectric substrate either as a uniform surface coating or in a predetermined pattern. The initial electroless copper deposit is thin and may be further built up by electroplating or may be deposited directly to full thickness. In general, electroless plating is used for both functional and decorative coatings in a variety of industries, like e.g. automotive, aerospace, naval, medical devices, fittings, electronics, etc.[0003]A huge field o...

AI Technical Summary

Benefits of technology

The patent describes a system and process for recycling catalytic precious metals from an aqueous processing solution. The system includes a holding tank and a filtration unit with ultrafiltration capabilities. A heat-exchanger is used to lower the temperature of the processing solution before it reaches the filtration unit. The system can produce a permeate stream with a reduced concentration of cataltic precious metal and a concentrate stream with an increased concentration, allowing for efficient recycling of the precious metals.

Problems solved by technology

Due to the content of valuable precious metals the catalytic metal colloids represent one of the major cost factors in electroless metal deposition processes.

However, recovery of the catalytic metal from the rinse is difficult because the catalytic metal is contained in these aqueous solutions only in small concentrations.

Therefore, the rinse is often discarded with the loss of the valuable catalytic metal.

In addition to the loss of catalytic metal from rinses, catalytic metals also may be lost from the catalytic metal colloidal solutions or baths since these solutions become ineffective by contaminates of the period of use.

There are many disadvantages with such a method.

Electrolytic cells can be costly.

Because of the weight of fluids, the cost of transporting the bath to the recovery site is expensive.

A significant drawback of the methods and systems know from the state of the art is that over the time of use the filter used to separate the colloids and / or metals form the aqueous solution starts to clog and needs to be cleaned, e.g. by back flushing the filter.

Hence, the filter does not provide a constant stream of filtrate, but filtrate flow rate will decrease with increased clogging and rise again after cleaning.

For this system, no steady state of operation can be gained over an adequate period of time.

Furthermore, cleaning operations, like e.g. back flushing causes additional mechanical stress to the filters uses which results in an increased need for maintenance of the filters, or in worst case damages the filter.

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