Don't you know about the MECER process - Recovery of copper and etch solution from ammonialcal PCB production. Have a look at our website http://www.meab-mx.se - Projects.

I had not heard of the MECER Process but will look into it.

Not sure that the requirements to remove organic in plating would be much more stringent than those to remove organics in electro winning. In any case if you really need it, an activated carbon column should do the trick. So, application of SX for metals scavenging from plating circuits is known and it should be possible to apply to other scenarios as well. One issue may be higher concentrations of metals than are usually encountered in hydrometallurgical applications, but you have to look at it case by case.

Depends what the application is for. If it is for Cu removal from ammonialcal etching (of the PCB) solutions - a lot of work has been done over the past 30 years (or more) and there are processes. For applications where SX is to be used on the actual plating solution (as opposed to the etching solution for PCB), things can get a lot trickier –

•because of potentially soluble SX organics

• interactions of (a) with other organic additives platters often use

•if the metal-plated product is of high value then even minor imperfections, as a result of (a) and (b), can ruin it.

Activated carbon may or may not work. So if SX is considered for metal recovery from actual plating solutions one will need to be very careful during the test work/process development.

Regarding organic removal, zinc EW has a target of < 1 mg/L organic in the electrolyte (preferably < 0.5 mg/L). There are at least two commercial operations that have SX ahead of Zn EW (and a third in construction) so it can be done, but requires quite stringent steps - typically an after settler, flotation columns, and then carbon columns. (Of course, measuring such values accurately is a whole other story!)

The use of Cu SX in the PCB industry is widespread. There are literally hundreds of tiny units spread across southern China at each little PCB "shop" recycling spent etchant and producing low quality EW Cu. One of the problems is that the ammonia system degrades the reagent so leading to high entrainments and Cu quality issues.

But regards the plating industry, like for example recovery of nickel from electrodes nickel plating, there seems to have been no widespread commercial/technical acceptance despite some published articles on the same.

The use of SX in recovering plating solutions involves a lot of testing and precaution due to the possible interferes of the organic substances on the plating surfaces and in the solutions. One of the worst substances turned out to be kerosene! The complexion agents are usually not so harmful. Some similar substances might already be involved.

Conclusion: Very careful test work is recommended. A special cell, the Hull cell, is used to test the electro-chemistry. The Hull cell is a specially designed cell for carrying out practical plating tests on electroplating solutions.

You are right; the Hull cell is a good practical tool for checking electrolyte quality. Interpreting the results is a bit of an art, as it provides indication for some, yet not all, potential problems.

The Hull cell shows contamination in the electrolyte by discoloration or "staining" on the panel. The rule of thumb is the Hull cell shows the problem before it gets bad enough to cause scrap but not always. From the comments received so far it appears that SX has most applications in treating plating waste solutions e.g. PCB etch solution.

The MECER process recycles 95 % of the etch liquor back to the etching machine. However, I agree that most applications are treating plating solutions without recycle.