Homebrew PCBs

Neither iron nor copper are actually "heavy." Atomic number is part of the
definition. Fe (iron): 26 / Ni (nickel): 28 / Cu (copper): 29 / Zn (zinc):
30. Each of these needed by all life (in the proper quantities, of course).

Now, these buggers *are* heavy: Hg (mercury): 80 and Pb (lead): 82. Useful
but nasty metals.

Sorry for the quibble.  Heavy metals is commonly used to mean "toxic metal
compounds." That's okay. I need coffee. I'll feel better.

73,

Todd
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K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
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QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


On Sun, Mar 10, 2013 at 11:30 AM, Charlie Taylor <scubadogct@...>wrote:

> in my opinon the preasence of ferric is not the issue. It is tje heavy
> metals that is the peoblem.
> On Mar 10, 2013 1:03 PM, "Dave Sage" <davesage12@...> wrote:
>
> > **
> >
> >
> > Perhaps someone with some knowledge on public works and sewage treatment
> > can
> > clarify this for me.
> >
> > I guess it must be the copper in the ferric chloride etchant that we
> > dispose
> > of that is the problem - is that correct? Is there actually copper per se
> > any more after the reaction of etching?
> >
> > I'm pretty sure somewhere in the sewage treatment process, after gross
> > solids are removed, the water in the sewage system is sent to settling
> > ponds. While in the ponds ferric chloride is added to act as a flocculent
> > i.e. an agent that causes solids to gather together in clumps for easy
> > removal. If this is the case, would it make any difference if there were
> > some ferric chloride in the system to begin with (from flushing etchant
> > down
> > the drain)?
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
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