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Saving zinc from zinc dross
I work in dry process hot dip galvanizing line. We use zinc about 100 mt and lead about 30 mt in kettle and we make production only 8 hours a day. So, of course, much zinc dross is formed in kettle. We take out zinc dross with big steel shovel by using crane and manpower.
There are much pure zinc in our zinc dross. We think it is because of our simple drossing method. So, I would like to know
-whether there are any drossing methods and equipments to take out zinc dross in which less pure zinc containing?
-whether there are any ways to take out zinc from zinc dross?
I would like to request that please, somebody kindly advise me.
Production Manager - Yangon , Union of Miyanmar
January 19, 2011
January 21, 2011
This is a common way to remove dross, and in the opinion of many, better than the clamshell type grabs.
But does your shovel have holes in it?
It should have 10 mm diameter holes spaced at about 50 mm apart, in every direction.
And when you remove the full shovel from the zinc (presumably on a crane), rest it on the kettle edge a while and "work" the dross with a shovel. That is, dig the shovel in and out to agitate the dross.
Lots of liquid zinc will flow out and this can go back into the kettle. It's not pure and totally free of dross, but that doesn't matter.
The only dross you want to remove is very granular, dry looking sandy looking grainy stuff. If there's shiny zinc bleeding from it, then you didn't work it enough.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
January 30, 2011
January 31, 2011
Dear Mr.Geoff,
Thanks a lot for your kind reply.
Our drossing way is almost the same as your explanation and we make drossing at about 450 °C of zinc bath temperature.
- Yangon, Union of Myanmar
January 31, 2011
Dear Sir,
Perhaps you can try drossing at a temp of 440ївч.
Regards,
- Selangor, Malaysia
February 4, 2011
Sir:
I strongly recommend that you use a long probe type K thermocouple and digital thermometer and measure the zinc temperature from top to bottom in your kettle (including the dross zone) to determine the best temperature for drossing. It is true that a lower temperature causes the dross to form bigger and longer needles which allows better zinc removal. Too low of temperature freezes up the entire dross scoop.
Regards, Dr. Thomas H. Cook, Hot Springs, South Dakota, USA
Galvanizing Consultant - Hot Springs, South Dakota, USA
February 7, 2011
Dear Mr.Leong and Mr.Cook,
Thank you for your kind suggestions. I will follow to your advices.
- Yangon, Union of Myanmar
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