What impurity is the sky-blue new solution in the wet process for producing electrolytic zinc?
Thread Content
As the title suggests, what impurity is responsible for the sky-blue color of the new solution in the wet zinc electroplating process? It’s certain that it’s not copper. The sample taken in a glass cup is colorless and transparent, but it turns sky-blue in the tank containing the new solution. This situation has existed for several years without any problems; it only started appearing in recent days. The new solution has passed quality tests, and there are no signs of damage to the zinc plating surface, yet there are numerous bubbles on the surface of the electrolytic cell, resulting in a low efficiency of less than 80%. I would appreciate it if everyone could help analyze what impurity might be causing this issue.
How much zinc is in the new solution? Also, pay attention to checking the auxiliary materials that have been used recently; it’s possible that these materials have introduced other impurities.
The zinc content is around 130. The problem now is that the full analysis of the new solution shows no issues.
Do not be limited to impurities analyzed in their entirety. Trace back step by step from the place where the change occurred; for example, were the reagents used for purification, such as xanthate or antimony salts, changed in terms of batch or manufacturer? What is its quality? New impurities resulting from factors such as production auxiliaries cannot be detected through a full analysis of the new solution. The electrical efficiency is low, and there is foam on the surface of the tank; I think it might be some kind of organic substance that increases the surface tension of the solution.
Reply to 1# sytaenf: Personally, I think it might be ferrous sulfate.
The auxiliary materials have not changed manufacturers, nor have they been newly purchased. Mainly, the raw materials change a lot and are of mixed quality. What I mainly want to ask now is, apart from the conventional elements that are analyzed in full, what other impurity elements can cause board burning (such as silver).
Reply to 6# sytaenf: The possibility of silver is low; there should be very little silver in the leachate. And even if there is some, it will be removed during the purification process. AgCl precipitate will also be formed. Let’s get creative for a moment: given that seawater is sky blue, we can speculate whether there are other cations in the electrolyte. (Na, Mg, etc.)
Reply to 5# Ding Kejian: If it’s ferrous ions, then the raw material contains too much iron, and oxidation is insufficient during leaching. It is indeed possible; it is recommended that the original poster check for ferrous ions. But in the overall analysis, iron should refer to total iron, right? How is the specific measurement method carried out?
I know it’s not silver; I was just giving an example of those elements involved in unconventional analysis (such as silver), but I’m not aware of any other elements that could affect zinc production. The iron content is determined using ICP for total iron; we have conducted tests here as well as at Zhuzhou Iron and Steel, and there are no issues.
Reply to 9# sytaenf: This means that the influence of iron can be ruled out. I wonder if the new liquid is still sky blue? Is the precipitated zinc still normal?
If the impurity components in the new liquid are within acceptable limits, I personally think it’s a problem with organic substances.