Zinc sheet displacement for cadmium extraction – how to achieve liquid-solid separation
Thread Content
A small factory came asking to use zinc sheets to replace cadmium. The specific process is as follows: leaching and filtering of copper-cadmium slag – displacement with zinc plates – liquid-solid separation – compression of cadmium mass into pellets. I learned that the method of using zinc plates to displace cadmium was first employed at the Huludao Zinc Factory; in this approach, zinc strips (or sheets) were bundled together and placed into the tank to carry out the displacement process. I checked the literature; in the laboratory, zinc sheets with a size of only 1 cm2 are used, and an excessive amount of them is applied. I would like to ask the experts: how can zinc sheet displacement be achieved on an industrial scale? My question is, after the displacement process is complete, how can excess zinc sheets and cadmium wool be separated?
This post was last edited by Eguan Manying on 2013-12-7 at 14:38. The treatment methods used for copper-cadmium slag seem a bit outdated to me these days; what do others think?
Two displacements can be considered; in this way, the slag from the second displacement can be reused in the first displacement
The relatively complete replacement by zinc sheets is also a current research focus. I’d like to ask, in which aspect are we falling behind? Thank you!
Secondary displacement: my understanding is that the first displacement yields a purer cadmium alloy, while in the secondary displacement, there is an excess of zinc. I hope it can be explained in more detail. Thank you!
That’s the principle; the specific approach should be determined based on the circumstances
What we did at Danxia Smelting Plant was not all sent back; only what could not be handled was returned. At present, given the strong capacity of subsequent smelting equipment to handle impurities, the requirements for crude cadmium are quite flexible.
I looked around; it’s still quite popular to do this these days. First, prevent zinc powder from entering the lead. Are there any other reasons?
Last time, our factory went on a visit to another facility that also used zinc sheets to replace cadmium; there they placed the zinc sheets in a frame and stirred them slowly to carry out the replacement process, with the excess zinc sheets being removed afterward! This way, there won’t be an excess of zinc; the part at the bottom of the tank is directly compressed by the jack!
What kind of frame should be used to hold the zinc sheets, and what is the effect of stirring on the displacement process?