a11051605 - 14-9-2019 at 18:08
Was wondering if any one had a good flocculant to use in a lye solution. I know their are brand name flocculants you can buy off the shelf but was
wondering if any one could recommend a decent flocculant that you can make at home? Iv seen mention of aluminum chloride or iron sulfate but am not
sure. Looking to help coagulate hydroxides from a sodium hydroxide solution that was used to strip soder mask from some pcb boards, expect most
hydroxides present to be tin and lead. Any thoughts would be appreciated.
Sulaiman - 14-9-2019 at 21:20
I do not think that there will be lead hydroxide or tin hydroxide present,
sodium stannate https://en.wikipedia.org/wiki/Sodium_stannate
and
lead(II) oxide https://en.wikipedia.org/wiki/Lead(II)_oxide
are more likely.
Sorry, I have no idea what to use as a flocculant
a11051605 - 15-9-2019 at 18:36
Ah maybe, ya maybe the sodium stannate is possible, looking how to salvage any metals in solution or that have precipitated out of the lye solution.
Suspect main metals present are lead, tin, and maybe a little silver in various forms of oxide or hydroxide from the sodium hydroxide solution. Lots
of literature on how to process acid waste but hardly anything on bases.
happyfooddance - 16-9-2019 at 11:22
You haven't indicated the concentration of your lye solution or its known/suspected Pb/Zn content, but activated carbon should work. Bases stick to
carbon pretty well, though, and a high concentration of lye will surely make it less efficient. You can filter the carbon and burn it (fumes!) to
recover your metals.
With acidic solutions metal recovery is usually done with electrolysis. Depending on your process needs and how much zinc you have, that might be
easiest way for that one.
a11051605 - 16-9-2019 at 19:01
The concentration of the lye solution is around 1.75 to 1.5 mole. Have 2 pounds of lye dissolve in 4 gallons of water with additional 1950 ml of 12%
hydrogen peroxide. Unknown quantity of metals in solution.
[Edited on 17-9-2019 by a11051605]