Thoughts on waste treatment

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solar_plasma

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Feb 27, 2013
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Since I am not satisfied with the known methods to treat acidic metal chloride waste solution (thinking of kovar right now) from recovery processes, I thought a lot about it in the last time. Maybe I have got an idea (or I just forgot, that I read it somewhere) and I'd like to hear some opinions:

What if...

♦ we cement most, maybe even all, metals with aluminium (having AlCl3 left)
♦ filter at low pH
♦ then add NaOH to form gelatinous aluminium oxide hydrates at pH4-5(maybe up to 7) and NaCl
vaporize most of the water
calcine to form Al2O3
wash&filter
♦ the NaCl solution pH could be raised to pH9-10, filtered again if any solids precipitate and brought back to pH7.

We would be left with dry metal powders, NaCl solution, dry Al2O3 powder. The advantage should be, that the solids should be easier to filter.

The only new thing would be the calcination step.

???
 
The only concern I see is forming aluminum chloride which is a neurotoxin. Considering that almost all antiperspirant's contain aluminum, one must be careful of the amount of exposure because aluminum has an accumulative effect and builds up in body tissue over time. I feel that extra caution should be taken to avoid exposure as aluminum chloride is readily absorbed through the skin and mucus membranes.
 
Exactly my concern, too. I would love to use Mg or Ca instead, but only Al is cheaply and readily available.
 
aluminium will not cement nickel and is horible to filter. also aluminium is so reactive your that it will react with water itself making something else. it take forever to filter and forever to settle your cemented metal. and when you try to to turn your aluminium waste into hydroxide they too took foerever to settle or filter.
you should avoid it.
 
Bjorn

For HCl waste solutions zinc is a much better choice then aluminum - die cast is zinc

here is what I use :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=59&t=20481&p=209970&hilit=zinc+conduit#p209970

The metals dropped out using zinc to cement them out filter much easier then metals cemented with aluminum

Edit to add; - you can then set up a "wick filter" system to filter the zinc hydroxides after adjusting the PH up with NaOH (will try to post pics later)

Kurt
 
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