Cyanide, its uses and its dangers

A. Hi Robert. One of our very helpful "regular responders", Geoff Smith, knows a great deal about this, and you could start with his paper: Cyanides in Metal Finishing Risks and Alternatives"

But it is very important to recognize that local and country laws trump any "recommended practice". Last time I checked, for example, here in New Jersey it was required to have a cyanide antidote kit on hand, whereas it was reported to us that nothing but oxygen is to be used in England; and the chaos induced by such laws has defied belief "FDA Keystone Cops Raid Keystone" (I realize you're in Germany, but most of our readers are in the USA and need to realize the situation here).

Beyond those references, and while awaiting replies, the earlier entries on this thread should be helpful. And put a cyanide gas detector on your "must have" list. While I don't think you need much ventilation, a lip-type or push-pull exhaust system should be provided.

Cyanide poses dangers two ways, both as hydrogen cyanide (HCN) gas and as an ingestible powder or liquid. Decades ago I dropped the cap to a pen on a plating shop floor; as I reached for it, a wiser gentleman said leave it; although death probably wasn't likely I might have picked it up and later chewed on it while lost in thought. So, while it's important to study the HCN gas possibilities, don't forget the ingestion route.

Luck & Regards,

A. Hi Robert
A few points for work with Cyanides:
1. Ventilation is mandatory
2. Ensure bath pH is 12 or higher
3. Do not bring any acid or acidic solution to the proximity of Cyanide bath.
4. Always double check all chemicals that are added to the bath (for bath mixing or replenishing)
5. Check how waste rinse water (after Cyanide bath) will be treated. It cannot be mixed with acidic waste and it may require special treatment (Cyanide destruction).
6. Use cartridge-respirator [on eBay or Amazon] when mixing the bath
7. Portable HCN detectors are recommended (they may require calibration with HCN gas)
8. Check local regulations about antidotes and first response. You may want to coordinate with local ambulance services and/or nearest hospital - what to do in a case of poisoning.
*You may want to check https://www.cyanidecode.org/ (They are focusing on mining, but there is useful information and references)
Good luck.

A. In establishing the toxicity of a compound, it is necessary to determine the lethality. To be more precise, the median lethal dose LD50 which will kill 50% of the subjects.
Due to the shortage of volunteers for this experiment it is carried out on lab animals and the result expressed as for example LD50 x g/Kg (rat) as it depends on body mass.
But not all animal speies are equally susceptible so the result cannot always be applied to humans. In the search for suitable candidates, man's best friend was investigated...
Barcroft (1931) exposed himself and a dog simultaneously to an estimated 600 mg./m3 of cyanide. After 1.5min. the dog collapsed and was declared dead. He removed the body and returned to the test chamber for a further 9 min. when he experienced ' ..difficulty to concentrate' and terminated the test. On returning to the laboratory next morning to bury the dog, it was found to have fully recovered.
Evidently dog is not a good analog for man.
Two minor points for the worriers. In military terms, as a potential war gas it is considered 'toxic, but only just' There are far worse poisons.
Cyanide even had a brief moment as a dietary fad under the erroneous name of vitamin B17 giving rise to 'The Little Cyanide Cook Book' by June de Spain; still in print and advertised as an anti cancer diet.
People will believe anything!

A. Copper cyanide is CuCN. Copper cyanide is an important industrial chemical for electroplating but cyanide is a very powerful and very fast acting poison.

A. Just keep in mind that a single drop of cyanide solution accidentally splashed into your eye could kill you.

A. While cyanide solution is very poisonous, with somewhere around 0.4 tenths of a gram, if ingested, will cause death, I don't think that a single drop in the eye is a death sentence.

With about 20 drops to the milliliter, and a specific gravity of 1.2, a drop would weigh around 0.06 grams, and not all of that drop is cyanide.

Of course, a drop of cyanide solution would really burn, and should be washed out with plenty of water. Safety goggles [on eBay or Amazon] or a face shield [affil links] should be worn by operating personnel.

A. I'm sorry guys, but as far as I know the "drop-in-the-eye" test was performed on a K-9. So I read in a very old chemistry book by Puig.

A. Because the eye socket is a mucosa the absorption of a toxin is almost instantaneous if direct contact is made, dependent on the MPE of the chemical, death will be imminent.

George,

Wait a minute, the cyanide is dangerous to handle because it is a deadly poison, the alkalinity would make it burn too. Yes, I have handled cyanobrik with my bare fingers, it was a very irresponsible thing to do. I used to crawl and jump around automatic machines while they were running too, which is Russian Roulette only more so.

DON'T HANDLE CYANIDE WITHOUT PROPER PROTECTIVE EQUIPMENT AND TRAINING! DON'T SUFFER OTHERS TO DO SO!

DON'T GET IN THE WAY OF AN AUTOMATIC HOIST, NOT EVEN ONCE!

ALWAYS CHANGE YOUR CLOTHES AND BOOTS WHEN LEAVING A PLATING SHOP AND RE-ENTERING A HOME OR CAR OR WHATEVER. DON'T DRAG CYANIDE AND OTHER CHEMICALS INTO THE HOME WHERE OTHERS CAN BE EXPOSED (WITHOUT THEIR KNOWLEDGE, WHICH IS EVEN WORSE)!

I certainly admit it, George -- the truth shall set us free. Yes, some people even used to wash their hands in cyanide tanks because it is 'the world's best cleaner'; then after rinsing, dip them into an acid tank to neutralize the traces of cyanide so they wouldn't get festering sores at their cuticles and cuts.

What I don't do is advocate it; many people have died of cyanide poisoning in plating shops. I count myself lucky for not being one of those many. I came close on two occasions -- having been sent out as a young field engineer to work alone (never acceptable), while utterly unaware of the dangers of cyanide.

A. Hi Akash. Unless it is an extremely small amount, yes, they die surely -- quickly, although not quite instantly. Why do you ask?

Regards,

A. Hi Lorena. Your question is awfully vague.

Cyanide is used in (and essential for) silver plating and brass plating, and is useful in some types of copper plating and zinc plating. It's used for certain jewelry cleaning operations. It has traditionally been used a fumigant for silos but, that not being my field, I don't know if it still is. It was at one time used as rat poison and the main ingredient in California's gas chambers.

But it is also present in apples, lima beans, and almonds -- It's been estimated that 10 pounds of lima beans would constitute a fatal dose. So who has been given access to lima beans and why? :-)

Now it's your turn: WHY do you ask? Thanks!

Regards,

A. Lorena,
There are an awful lot of chemical compounds that can be utilized to perform useful tasks, but can cause tremendous harm to biological tissue if handled improperly. Some such substances can be found in the cleaner isle of any grocery store.

Cyanide has a pop culture reputation as a poison, but since it merely refers to a carbon atom and nitrogen atom with a triple covalent bond between them, it's not really an exotic thing at all.

A. Some articles of commerce that are unquestionably harmful, like tobacco for instance, are readily available. Substantially all of the cyanide used is utilized in relatively benign, useful industrial processes, even though the possibility for nefarious use exists.