Zinc Concentrate: Smart, Powerful Tank Design Tips

Summary for zinc concentrate Discussion

zinc concentrate for an alkaline non-cyanide zinc rack line should not be made by guesswork, according to the reply from Ted Mooney. The questioner, Mike Anderson, asked whether a steel 55-gallon drum with 20 gallons of 50% caustic and zinc balls, plus slow mixing, would be a workable way to dissolve zinc and what concentration to target. Ted cautioned that a casually designed zinc generation tank is not a good substitute for a carefully engineered one. He pointed readers to an article on the fully correct design of zinc generation tanks and emphasized that contact with steel is essential for zinc to dissolve. He also noted an unexpected tip from the article: bluing the steel with a torch can improve dissolution. His advice was to follow the article as closely as possible for a trouble-free, labor-saving installation rather than trying to "shoot from the hip."

Alkaline non-cyanide zinc plating is done from a solution containing zinc and caustic soda. But using zinc anodes in the plating tank tends to dissolve zinc into the caustic solution too readily, with the zinc concentration climbing too high for ideal plating. Using a balance of zinc anodes & non-dissolving steel anodes only works ideally if production rate never varies and the line runs 24/7.
The best answer is probably to use non-dissolving steel anodes in the plating tank, and a separate “generation” tank where zinc metal dissolves into the caustic … and then circulate solution from the generation tank to the plating tank at an appropriate rate.

Q. I am looking to make up a solution of zinc concentrate for our alkaline zinc rack line. My plan was to use a steel 55 gallon drum, add about 20 gallons of 50% caustic and zinc balls. Does this sound about right? I’ve read a slow mix will also help the zinc dissolve faster. Is there a certain concentration I should shoot for (via calculations) or can this be a ‘shoot from the hip’ process? Thanks.

Mike Anderson
Lab Tech – Hollidaysburg
March 14, 2025

A. Hi Mike.

A casually designed zinc generation tank will not be a good substitute for a carefully engineered one. Please study this outstanding article ⇨
about the fully correct design of zinc generation tanks before trying to decide which shortcuts will be okay 🙂

Per the article, contact with steel is essential for the zinc to dissolve, and a new one on me was that bluing the steel with a torch will improve the dissolution. My suggestion is to try your best to do everything it suggests for a trouble-free labor-saving installation.

Luck & Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey

Need quick confidential answers? $25
Need project assistance? $100/hr.