Feasibility of electrowinning technology for electroplating waste recovery?

? Hi Daren. Perhaps I'm misunderstanding you, but electrowinning has been used for recovery of these processes in hundreds of plating shops for decades. I could name a dozen commercial vendors of these cells. There have been (and in some cases there are patents on) recovery onto simple stainless steel anodes, reticulated copper, and high surface area carbon. Numerous techniques to minimize the boundary layer have been used including 'scraping' with glass beads, high energy impingement, high rate recirculation, and even pulse plating.

As for concentration, in many cases, the wastewater is passed through ion-exchange (an ideal technology for high volume - low concentration wastes like plating rinsewater), and then the regenerant is electrolytically recovered. My point is that there are hundreds of real case histories so you don't have to make any conjectures about the feasibility when hard evidence is available.

Maybe you're proposing a radically different technology than I've mentioned here?

A. Okay, let's see if anyone has comments. Our experience has been that many plating shops are generally willing to help suppliers develop and prove new equipment and processes as long as there is a reasonably possible benefit. You can advertise your cells on this site or anywhere you wish. But 'typical' concentrations and volumes are hard to say because everything from dilute rinsewater (sometimes concentrated via DI) to concentrated plating solutions has been recovered, and plating vessels range from 1 l (or less) beakers [beakers on eBay or Amazon [affil links] for specialty solutions on up to tanks of 15,000 gallons and more. The average plating tank size for production jobshops is probably about 1000 gallons. Good luck.

A. We are involved in many EW projects for different metals such as copper, zinc, cobalt and nickel and see a lot of potential for EW, particularly in combination with SX technology. Also IX has been applied to very dilute solutions which I believe is the particular field you wish to tackle.

A. Hi Helmy. Although anything is possible, if this is a one-time application it's probably not economically feasible depending on the volume of sludge on hand. If it's a continuing situation, the usual question is whether it's more feasible than alternate approaches. To that, my response is: "probably not". Electrolytic recovery at the source (the rinse tank after plating) is generally a far easier, less expensive, and more practical approach than precipitating the metal into a mixed-metal sludge, then having to redissolve the metal again so it can be plated out, then re-precipitating everything else again :-(

And once you're back to recovery at the plating tank, electrolytic recovery may or may not be competitive with or superior to other recovery technologies. Evaporative recovery or recirculating the rinse though a DI canister is sometimes better.

Regards,