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Safe disposal of cyanide


I have been looking (unsuccessfully thus far) for specific
instructions on the safe disposal of cyanide. In particular,
potassium cyanide and sodium cyanide, both in powdered form. I have
found a reference for neutralizing with sodium bicarbonate but it
didn’t specify the ratio. Directions, anyone?

Amy Johnson

I called New York State Dept. of Environmental Conservation a few
years back about disposing of cyanide. When they realized that I
wasn’t a plater, and just an occasional user they said to just
dispose of it by diluting and pouring into the sewer. Their answer
was that the small amount I was using would be removed by the sewer
treatment or otherwise have no impact environmentally. Their words,
not mine.

I’ve searched for ages on the internet looking for the reaction you
mention so that I could calculate the ratio for you, but to no avail
I’m afraid.

There is however an Orchid post in the archives called “Cyanide
Neutralization” by John Burgess on 4th August 2001. He prescribes a
method for neutralizing cyanide salts with ferrous sulphate.

I hope you get rid of the nasty stuff as soon as possible.


There is however an Orchid post in the archives called "Cyanide
Neutralization" by John Burgess on 4th August 2001. He prescribes
a method for neutralizing cyanide salts with ferrous sulphate. 

There is another description from 18th November. As it was me
writing, let me just copy-n-paste.

According to my (rather old) Brepohl, in the context of disposing
cyanide solutions from electro-plating jobs, he recommends the
following proceduRe:

  1. Put the cyanide solution into a plastic bowl

  2. Add a 10…20% ferrous sulfate (FeSO4) solution until color changes
    to at first rost colored, later chartreuse (greenish-yellow). This is
    potassium ferrocyanide / yellow prussiate of potash - K4Fe(CN)6

  3. Now add a 10% ferric chlorid (FeCl3) until the solution gets blue.
    This is Prussian Blue / Berliner Blau / Turnbull Blue /
    Eisen-hexacyanoferrat(II) - Fe7N18C18


I’m not sure where you found info on neutralizing with sodium
bicarbonate. What I’ve seen is pretty specific and for both say much
the same thing. Go to for any disposal
questions, since many chemicals aren’t easily disposed of without
affecting the environment. The laws around it are also pretty

On TOXNET, on the HSDB, it says this about potassium cyanide:
POTASSIUM CYANIDE CASRN: 151-50-8 For other data, click on the Table
of Contents

Disposal Methods:

Generators of waste (equal to or greater than 100 kg/mo) containing
this contaminant, EPA hazardous waste number P098; D003, must conform
with USEPA regulations in storage, transportation, treatment and
disposal of waste. [40 CFR 240-280, 300-306, 702-799 (7/1/96)]PEER

Cyanide salts should not be flushed into any drain which may contain
or subsequently receive acid waste… Cyanide process waste
solutions and flushings from spills should be passed through a
cyanide waste disposal system. /Cyanide salts/ [NIOSH; Criteria
Document: Hydrogen Cyanide and Cyanide Salts p.27 (1976) DHEW Pub.
NIOSH 77-108]

Potassium cyanide is a poor candidate for incineration. [USEPA;
Engineering Handbook for Hazardous Waste Incineration p.3-10 (1981)
EPA 68-03-3025]


I would beg you to refrain from dumping cyanide in any water system,
and not to trust the opinion of a telephone responder’s opinion. At
the least neutralize it with iron sulphate, or radio shack type
etchant solution before dumping. The iron particles are far easier
removed in waste water treatment than cyanide in a pure form, not to
mention the potential danger if the delivery of the cyanide you are
dumping is imperfect; say- a leak between your sewerage pipes and
the tie into the public system…Would you want your pet or kid
walking around in grass of which cyanide has leeched out of a cracked
pipe then carried back into your home still active to a degree- and
any degree is dangerous when cyanide is present, then licking its
paws or untying its shoes and absorbing it through a mucus membrane
and you,nor the emergency services you call when the being convulses
can’t figure out where to look, or for what until it’s too
late???..I’m betting no is the answer…

I thought my own method would be obvious, however I have not seen
anyone else come out with it in print, so for what it is worth,
please check with your County Environmental Health Department and
inquire about scheduling of their Household Hazardous Waste
collections. My County here in central Michigan has at least one
each year, and they will take your cyanides and acids for proper
disposal. In addition, they do this at no charge, although they do
ask for a donation to help offset the costs.

Jon Michael Fuja

From Cyanide Destruct Systems, Inc

Interesting Facts About Cyanide A naturally occurring and widely
misunderstood chemical. Cyanide has received a bad rap over the
years. The truth is without it our daily lives would not be the same.

It is one of the most common chemicals in the world.

It has a reputation that is worse than the toxicity of the chemical
itself, perhaps due to infamy gained from B-movies of decades ago.

It is used is more industries that can be mentioned here, including:
pharmaceuticals, paper, a variety of plastics, gold mining, dyes
(the dye in blue jeans, for example), electroplating, heat treating,
etc., etc.

Common paints and adhesives contain cyanide.
Cigarette smoke contains cyanide.
Cyanide gas is the most toxic form of cyanide.
Cyanide gas outdoors is rapidly dispersed.

In it’s normal high ph state, cyanide gas is not created and is quite
safe to breathe and smell.

If you are exposed to cyanide gas or ingest cyanide, and you are able
to talk about it later, you will have no long term or unknown health

A lethal dose of cyanide is contained in 3.7 pounds of lima beans.
A lethal dose of water is 17 litres consumed very quickly.
A lethal dose of gasoline is the same as cyanide.
Cyanide is contained in 110 different plant families.

Facts ripped out of a data base are educational- well and good, the
point is, in this context, the amount it takes to perform a bombing
operation (concentrated cyanide in capsules) is most definitely a
hazard and should not be done in the small studio without an
absolute knowledge of the process and correct and appropriate
disposal of the resultant solution and not, most definitely, a
process to be recommended to, convinced of the inherent safety of or
engaged in by novices…anything remotely similar is simply poor
judgement and mis-where the possible and uncontrolled,
results could be deadly. I for one wouldn’t like to read that because
of someone’s post on Ganoksin a new jeweler working at a kitchen
table made a mistake and killed everyone in the household, or the
capsules ( no one buys one-rather they are supplied in a box of a
minimum of 12 that I know of) rolled off the table, went unnoticed
and the family dog ate one…too many variables for “at home” or a
novice to deal with without being shown handling and process
explicitly and without the correct and legal method for disposal in
one’s location being at least known-much less adhered too… A cyanide
solution is not properly disposed of by dumping it into galvanized
pipes, older copper pipes ( what do you think the reaction on old
solder would be huh?), or certain types of plastic pipes and then
into a waterway- provided there is no leak between it and one’s home
or studio and the outlet- or what if the person recycles their
greywater and forgot that they dumped cyanide into it before leaving
the house in a sitter’s care when on a weekend of show going or
exhibiting???!.All-in-all there are better ways to achieve the exact
same result(s) without the potential dangers inherent with handling
a pure form of HCN. RER

At the least neutralize it with iron sulphate, or radio shack type
etchant solution before dumping. The iron particles are far easier
removed in waste water treatment than cyanide in a pure form, 

I’m not a chemist, but I’d be very reluctant to be reacting cyanides
with any sort of low ph (acidic) salt, such as iron sulphate (a
sulphuric acid salt) or the ferrous sulphate etchants. It may be the
ferrocyanides are less toxic, but I’d suspect the reaction itself
could generate hydrogen cyanide. And that’s something you don’t want
to do outside of specialized equipment. Commercial cyanide destruct
units do it exactly that way, reacting the cyanide with hydrochloric
acid or another such acid, which destroys the cyanide, but releases
cyanide gas. That gas is then absorbed by activated charcoal
filters, or fed to apparatus that incinerates the gas. Not a method
to play with unless one has proper facilities. Bleach, on the other
hand, reacts with cyanide oxidizing it to much less toxic cyanates.
Bleach, like cyanide is a high ph base, so hydrogen cyanide gas is
not formed. Diluted enough, cyanates are then safe to dispose of.
dilution is important, just as with disposal of small portions of
unreacted cyanide. Dilute enough, it is indeed pretty harmless.
Cyanide is not like nerve gas or anything. It’s dangerous, sure, but
in very dilute amounts, is found already in nature, and the liver is
pretty good at dealing with those small amounts. What makes cyanides
so potentially dangerous is not their particular toxicity, since it
actually takes a fair amount to be lethal, it’s the speed with which
it can kill, robbing you of the time needed to react to a poisoning
event. When highly dilute, this just isn’t a big problem anymore.
It’s not, for example, cumulative in the body (though long term
chronic exposure can cause harm). And remember that it breaks down
naturally in the environment, with sunlight. It’s just carbon and
nitrogen, so the results are not some lingering contaminant once it’s
broken down. The question is how to break it down. Please be very
careful about advising anything that lowers the ph. When acidic
enough, hydrogen cyanide gas is formed. And you really don’t want to
do that…


Jon Michael Fuja,

Thank you for bringing up the household hazardous waste disposal
option. I would like to second that mention of this as a great method
to dispose of ALL studio chemicals, used pickle, plating solutions,
patinas, etc. Santa Barbara’s household collection is FREE of charge,
every week, out at the local University. The EPA can also help you
find a household program near you, anonymously and easily, for proper
disposal. ‘Hobby Chemicals’ might be the description to use for your
local household disposal site.

I understand that the amounts of ‘toxic’ materials we all deal in
seem small, and ‘inconsequential’ but some of the seemingly innocuous
ones can play havoc with municipal water treatment… copper sulfate
knocking out beneficial microbes (good bugs that destroy bad bugs) in
sewage drain processing is an example (CS is a powerful
anti-microbial, anti fungal). Metals and Cyanides at levels not toxic
to people can be highly toxic to trout and other aquatic life. Look
up ‘cyanide fishing’ on the web for some inventive uses of these
chemicals. Gold mining as we know it would not be possible without
cyanide…but it is our responsibility to use powerful chemicals
judiciously and treat them properly when we are done with them.

The way I handle things in my studio is that if I wouldn’t eat it or
drink it, I pay to have it reclaimed / disposed of as waste, instead
of ‘dumping it’, no matter what I’ve ‘done to it’ to make it ‘safe’.
Period. Those are my guidelines. Why? Take a look at The Theory and
Practice of Goldsmithing, By Dr. Erhard Brehpol…Chapter 3,
Section 3…“Keep track of the receipt and disposal of all toxic
materials in a logbook, attaching receipts as documentation…” Dr.
Brehpol also characterizes even DILUTE solutions of sulfuric acid,
hydrocyanic salts, and soluble copper and silver compounds as “highly
toxic” (pp.97-99). If you want to protect yourself, and your
business, this seems like the best plan. And thanks Mr. C.
Lewton-Brain and Mr. McCreight. Why risk a problem with toxics
accounting later, when you are rich and famous? Why not be the best
professional you can be?

We, as metal workers, typically do not have the equipment or the
facilities to be sure (i.e. test / measure) that we have
appropriately neutralized all hazards to ‘safe’ levels (is that 250
parts per million of copper? (toxic?) or 25 ppm? (safe?). Did we use
’plenty of water’? The professional hazard treatment sites do, and
the household hazard sites will do it for you, again, probably for
FREE, and anonymously.

Spent pickle is a good example of this. Santa Barbara has a ‘Small
Quantity Generator’ business classification that allows for waste to
be properly treated / documented out at our local University for a
nominal fee. I suppose future waste-treatment superstars have a go at
it, wearing funny lab coats and looking serious… I drive there
every few months and they remove boxed and bagged waste from the back
of my truck, assuming that I am dropping off the worst toxic
materials ever…they arrive in hoods, goggles, plastic suits, the
whole shebang. I don’t have to tell them what it is, they assume the
worst, then test and treat it. Marvelously entertaining, really. Gets
me out of the studio for a bit, anyway.

I would bet that more and more towns and cities have similar FREE
programs, if you take a look. Sorry for the huge long post. Let


kelly johnson