Now to my request. You say that you work with cyanide
routinely in your shop. Would you be kind enough to describe
somewhat your shop setup where you handle cyanide? .... and
post it to me privately
And to the list. I’m not shy.
I use it in two places. At my day job, as a commercial jeweler
for a medium sized manufacturer there is simply an area set up as
a plating bench. A selection of various cyanide containing
plating solutions in beakers, with covers, sit in a larger
stainless tank of water, the whole heated with a gas hot plate.
This arrangment keeps all the baths at a reasonble plating temp,
though an average one, not the idea of each bath. And it
prevents what can happen with a single beaker on a hot plate,
overheating. Cyanide plating solutions should never be actually
boiled. Destroys free cyanide in the bath, giving poor coverage
and color. Gold baths that HAVE been overheated can sometimes
be rescued with the judicious addition of just a pinch of sodium
cyanide, but it’s best to not ruin the baths in the first place.
Anyway, back to the setup.
This shop has been in operation in an older downtown Seattle
office building for three generations, and the setup looks like
it’s been there the whole time. In short, it’s pretty casual and
looks crappy. There’s no fume hood, just a window nearby thats
usually open. It’s next to a sink thats used for all the shop
rinsing, including when items are removed from the pickle, and
the waste from the sink goes through two settling tanks before
actually hitting the sewers. In short, if anyone actually dumped
the pickle and then one of the plating baths down the sink, we’d
all be in big trouble real fast. But it simply isn’t going to
happen. Only those folks in the shop who know how to handle the
baths do so, and it’s with care. The very small amounts of
solution that go down the drain from “drag out” are not going to
cause any problems. Does this sound dangerously casual to you?
It would be if used in ignorance. The potential for accident is
certainly there. But in three generations of operation in this
shop, the only problems they ever have is that solutions get so
old the color isn’t right any more. And for the record, the only
problem the OSHA inspectors had (we ask them in from time to time
to make sure everything is in order) have ever had is that a
couple beakers were not labeled to their satisfaction (though we
all knew what was in em from the chart on the wall, they wanted
it on the beakers too) and the MSDS sheets were in another room.
Stuff like that. They had no problem with the actual use of the
cyanide baths. These are, by the way, quart sized baths.
In my home shop, which is not in daily use, I also have an area
set aside for storage of only cyanide and alkaline chemicals, in
a seperate part of the shop from any acids or things that should
not mix with the cyanides. It’s also deemed (by me) to be safe
from exposure to flooding or the like, which might, in some
accident, move spilled cyanide to another part of the shop. I
also do not have a fume hood, but I do have a strong bathroom
type fan mounted as an exhaust directly over the sink area in my
shop where I actually use these things. The venitilation seems
to be pretty good, as using even smelling things like liver of
sulphur doesn’t cause an odor build up, and testing with the
smoke from a cigarette or the like indicates pretty effective
exhausting of that corner. The fan cost about $60, and I
installed it myself just in the wall. Nothing fancy. For plating
processes, I use plain pyrex beakers, heating them on a small
electric laboratory hot plate, with an immersed thermometer to
track temps. The baths are set up only when needed, and the
solutions normally kept in their original bottles in the locked
cabinet mentioned earlier. In use, the sink water is run for a
couple minutes before I set up the plating bath, to be sure any
untoward residues are cleared out of the drain and plumbing
before I chance any cyanide spillage. Then nothing else (pickle,
etc) goes down that drain until after plating is finished and the
water again run for several minutes. Usually, there is no
significant amount of cyanide down the drain anyway, but I follow
this procedure just to be sure. Spent/waste gold plating
solutions are plated out to remove any remaining gold, then
diluted to several gallons volume for a quart solution, and a
gallon bleach added (this is a considerable excess. But bleach is
cheap…) This is allowed to settle, and liquid remaining is
poured down the toilet, and any residue settled at the bottom of
the container is collected and when the bottle is full of the
solids, taken to local toxic waste disposal facilities for
incineration when there’s enough. that usually happens only
about once a decade… I don’t use all that much, after all.
For bombing, the safety procedures are the same for the drain. I
attempt to retain all the bombed solution, putting it in a large
erlenmyer flask where I evaporate it down to solid. The open end
of the flask is fitted with a home made activated charcoal
filter, which helps in keeping this all odor free, and absorbing
traces of cyanide gas. It’s evaporated in a closed garden shed,
not in the house. The residue is kept seperate, and sent to
refiners when there’s enough. It’s not mixed with bleach, which
would just complicate metal recovery.
It’s important to note, as well, that I don’t have childen or
other uninformed people in the house or with access to the shop
areas
Hope this helps.
Peter Rowe