Energy efficient electroplating

A. Hi Ken. For many years the AESF had an "Enercon" committee (I served on it) which did investigations and reports on the subject. One of the more exhaustive efforts was an AESF/DOE sponsored "Energy Conservation Study of the Surface Finishing Industry" by Mazzeo and Holcombe in 1978: AES Research Project 46. You should be able to get a copy of this from NASF, and hopefully some of the other materials. Although it's old, little has changed, so no need to reinvent the wheel.

Regards,

A. Hi Jake. The most essential ingredient in addressing the specific situation you asked about is Faraday's Law, and it is simplicity itself: if your rectifiers move a given number of electrons from the anode to the cathode (measured in Ampere-Hours), a given number of ions of zinc should be oxidized and dissolve into solution from the anode and be reduced from the solution as zinc metal onto the cathode. In the case of acid zinc, which oxidizes into the Zn⁺² state, when you move 2 electrons, 1 zinc ion should follow. Faraday's Law says that 96,485 coulombs (ampere-seconds) will transfer 1 gram equivalent weight of metal if you are operating at 100% efficiency. If you look up the atomic weight of Zinc, and the density of zinc metal, you can also express this as 0.043 ounces of zinc should be deposited per ampere-hour, or that it will take 14.3 amp-hours to deposit 0.001" of zinc on one square foot of surface.

As mentioned, these numbers assume 100% efficiency (no electricity is wasted generating hydrogen gas from water instead of reducing zinc). So step one is to determine the present efficiency so you know the maximum theoretical energy savings possible. If the efficiency is approaching 100%, there is nothing that can be done to improve the deposition efficiency although it is very possible that replacing old rectifiers with new ones could deliver substantial energy savings.

Maybe start at .
This it is a well done, highly useful, one-page paper on the subject, linked to deeper data if needed. More universities & agencies than you can shake a stick at have gotten grants for "helping" the electroplating industry, so please start by downloading a couple of them rather than duplicating the spending and effort for the umpteenth time. Best of luck.

Regards,

A. Hi Jake.
Before I went any further, I would question why anyone would want to plate zinc onto stainless steel conduit.
Was it possibly a left over process from when the company once made conduit from mild steel?
My first reaction was that I could save a lot of energy by simply not doing it.
Please let us know if I misunderstood the question.

A. Hi Jake. I didn't immediately see the info on high-temperature potassium chloride plating. If you give me a URL I'll be happy to comment. But the truth of the matter is that very few of the improvements suggested in such reports are still in effect even a few years later, and it's not because the shops are too lazy to bother continuing to save bags of money -- please be a bit skeptical about the savings proposed and their long-term practicality. The single most important element of energy efficiency in electroplating is to not generate rejects, and this is best done by keeping the process under control, relying on long experience and the suppliers' technical data sheets. Please calculate the present plating efficiency before proposing any process changes; the calculation is easy, not hard.

Regards,

A. Hi Abhi. We added your question to an existing thread which will help answer it. Download the University of Minnesota paper. Never change any operating parameter in a nickel plating bath in an attempt to improve energy efficiency. Instead make sure they are well controlled so there are no rejects -- there is nothing as energy-inefficient as producing rejected work. Improved energy-efficient lighting will also reduce rejects.

Things to look at first for improving energy efficiency include: covering the tanks when not in use with practical covers, switching to push-pull ventilation if you presently have pull-only ventilation, and replacing old energy-inefficient rectifiers with new energy-efficient ones if applicable. Good luck.

Regards,

A. Hi Abhi. I have sketched a push-pull system to give an idea what I'm talking about ...

and you can study the details of why it improves energy efficiency in "Industrial Ventilation" .

If you already have new highly efficient rectifiers, and you already have a good ventilation system which you are not going to change, and you don't have downtime during which you can make use of good tank covers, and you have good bright lighting so you instantly spot problems as they occur, you're done.

Sorry, but trying to improve the energy efficiency of a nickel plating tank by adjusting concentrations, operating temperature, and other parameters instead of following conventional practice and the supplier's technical data sheet would be a fool's errand. Good luck.

Regards,