Need a HCN gas detector
- Thread starter kurtak
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Looking forward for your details, be safe mate.Very quick up date - Saturday I stared the recovery of the gold from the PGC salts I received
I have finished 5 batches & have 3 left to do (doing 5 liter batches with 200 grams of the salt dissolved in each batch)
Concerning the HCN detector - all work has gone without incident - UNTIL yesterday morning wherein the detector was set off
So I am VERY GLAD that I spent the $400 for the detector - especially being as I am one of those people that DOES NOT smell HCN
I will post more details as to how & why the detector was set off - as well as details of project/process when I get more time which is likely to be another week (plus/minus)
Kurt
The further you go with the electrolysis and turning the current up, and the lower the metal content gets the more HCN is gassed off.
The detector went off but did the canary die?UNTIL yesterday morning wherein the detector was set off
Seriously what do you think tripped it and what concentration of CN tripped the detector to sound the alarm?
Naughtius Maximus
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Almonds and apple seeds contain cyanide as a biodefense. Peach pits and cashews too I believe.
goldandsilver123
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All cashews nuts must be roasted because of the cyanide, even the "raw" ones are lightly rostead
Are you. guys implying Kurt was busy eating cashews and almonds instead of refining? Never eat in the presence of cyanide salts!!!!!!!
Mines 8ppm as a warning (slow beeps) and 15ppm. Relates to max exposure time at those levels. In fairness to try to set one off you've got to have the sniffer right over a vessel. There's no point having one inside a hood whatsoever, they should be used for ambient (if that's the correct word) atmosphere in the work area.
kurtak
Well-known member
Well - being as how I am the canary & typing this to report to the forum - no the canary did not die
That is the whole point of the HCN detector - to give you quick enough & early enough warning to back off FAST
The HCN detectors are made to detect "low" levels of the HCN & they do so " very quickly" (like almost instantly - if not instantly) for the very purpose of "warning" you to stay clear &/or back off NOW
What I found interesting as well as informative about that video was the chart he showed at about 4:20
That chart shows the effects of HCN bases time exposed to HCN at different PPM of exposure
At 18 - 36 PPM you will only experience "slight" symptoms after several hours of exposure
At 45 - 54 PPM it is tolerable for 20 minutes to an hour "without" immediate or later effects
At around 100 PPM is when risk of death starts to become a concern but even then if you are exposed for half hour to an hour
135 PPM = death after 30 minutes
180 PPM = death in 10 minutes
270PPM = immediate death
That is the whole point of the HCN detector - to give you quick warning when it is detected at low PPMs so you can back away before being exposed for extended time &/or before the HCN reaches lethal levels --- especially if you are a person that does not smell it in the first place
Generally speaking the HCN does not just come roaring out of the solution when CN is dissolved in water (due to the high Ph) as was demonstrate in the video - it was gassing off HCN but it was gassing off "very" slow & he was having trouble getting it up to the 15 PPM he wanted for doing his "safe" HCN smell test --- so he adjusted the Ph down (with sulfuric acid) to get more HCN to gas off for his smell test
IMO he did a very well controlled test to see first if he could smell it & if so what it smelled like but also in a way to insure the PPM level was within safe levels
It is because of the safe levels vs the unsafe levels that fume control is very important & IMO - especially if you can not smell it - you work with a "low" level detection device
That is why the very first thing I did before starting this project was built a fume hood in a room that is about 6 foot wide by 14 foot long - the hood is about 2 foot deep with a 3 foot X 3 foot face & powered by an 8 inch blower with the vent duct going up 10 foot - this set up is providing enough negative pressure in the room that it literally sucks the door into the room shut - there is a 2 inch gap under the door so the hood is constantly drawing air "up" through the hood - it exchanges air in the room "very" quickly - the door into the room is about 5 foot from the hood face so can exit the room is about 3 steps
In other words - ALL safety precautions where put in place - including the HCN detector before starting in on this project
And for what it is worth - this is not my first time working with Cn which is why I took the time & investment to set up to do this safely
But you already know all of this 4metals so this was posted to provide more info to the members of this forum concerning safety when working with CN - so thanks for the question(s) 4 metals
My next post will be how I set off the detector - which I actually did deliberately as a test
I may not get to that post until tomorrow
Kurt
edit to correct spelling
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The most important safety precaution when working with cyanide is to have a second person monitoring the individual engaged in processing.
That person can be otherwise engaged, such as reading, if they are in a separate work area and maintain a good peripheral awareness of the worker's activity.
A rapid response and an appropriate first aid kit can make a lot of difference to an outcome.
I suppose having an actual "Canary" as a workplace pet would be considered a cruel safety measure by modern animal guidelines. Still, before the development of modern alarms, they were the industry standard.
That person can be otherwise engaged, such as reading, if they are in a separate work area and maintain a good peripheral awareness of the worker's activity.
A rapid response and an appropriate first aid kit can make a lot of difference to an outcome.
I suppose having an actual "Canary" as a workplace pet would be considered a cruel safety measure by modern animal guidelines. Still, before the development of modern alarms, they were the industry standard.
I do it every single day to make sure it's working.
The most important thing for the work area is the CFM flow through the hood. With a 3 x 3 hood opening your minimum flow should be 900 CFM. But generally the major exhaust through the hood is for the person working in front of the hood. For extra safety I would place a spot exhaust duct over the vessel that is reacting and suck additional CFM specifically from over the reaction. Seeing that, in this case, you are exhausting (potentially) caustic cyanide fumes during the dissolve and precipitation, the blower can be a plain steel blower with fume contacting the working parts of the blower. This blower would be in addition to the hood blower.
But this seems to be an extreme case where there is concern about sudden release of cyanide gas for some reason. Typically in recovering Gold plating salts with zinc, the reaction is controllable and fuming minimal. The worst part should be the dissolving of the excess zinc from the well rinsed gold drop where you acidify and digest the zinc leaving the gold behind.
I have always separated cyanide hoods from acid hoods in separate work areas and I have always been fanatical about the exhaust CFM meeting certain minimums (100 CFM per sq.ft. of hood opening). I have stripped a lot of gold with cyanide over the years and never had issues. I have sensed the "almond" smell in the cyanide work areas because apparently my nose has that sensitivity. I have always relied on airflow through the processing area, as Kurt has done, and I'm still here to talk about it. Maybe that's why my hair fell out!
Don't get me wrong, the cyanide detection equipment has evolved considerably since I started in the refining game. The detector is a good safety feature in Kurt's setup, but as I am certain Kurt is aware of, the detector tells you when things go south and it is time to run (as Kurt said, 3 steps) but nothing takes the place of good safety practices around cyanide.
But this seems to be an extreme case where there is concern about sudden release of cyanide gas for some reason. Typically in recovering Gold plating salts with zinc, the reaction is controllable and fuming minimal. The worst part should be the dissolving of the excess zinc from the well rinsed gold drop where you acidify and digest the zinc leaving the gold behind.
I have always separated cyanide hoods from acid hoods in separate work areas and I have always been fanatical about the exhaust CFM meeting certain minimums (100 CFM per sq.ft. of hood opening). I have stripped a lot of gold with cyanide over the years and never had issues. I have sensed the "almond" smell in the cyanide work areas because apparently my nose has that sensitivity. I have always relied on airflow through the processing area, as Kurt has done, and I'm still here to talk about it. Maybe that's why my hair fell out!
Don't get me wrong, the cyanide detection equipment has evolved considerably since I started in the refining game. The detector is a good safety feature in Kurt's setup, but as I am certain Kurt is aware of, the detector tells you when things go south and it is time to run (as Kurt said, 3 steps) but nothing takes the place of good safety practices around cyanide.
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I have worked with cyanide for many years and I can smell it ,which I detest, I have scared many people with what they assume is my lack of safety and gung ho attitude but I do know the risks and where they come from, as we keep trying to tell members read and understand the processes they are employing and that way you know in advance the potential risks and how to be safe.
kurtak
Well-known member
This is correct - & actually HCN is produced & gasses off once you dissolve the CN in water (as was demonstrated in the video I provided a link to) it just does not come ROARING out of solution at lethal levels
This is also correct - you want the detector positioned so that it gives warning if HCN is detected in "very close" proximity to the air you are breathing in your work space - so I have had mine hanging on the wall just outside the hood about head high & about 2 & a half foot to the side of where I stand in front of the hood & it has maintained an absolute 0 reading at all times
As well - just to test it - I have taken it off the wall & held it over the top of the SS pot I am using to dissolve the salts in - my hood is "small" so with the 5 liter electrowinning cell & a few beakers in the hood I do this with the SS pot sitting on a stool "directly" in from of the hood - when holding the detector over the pot - after dissolving the salts the detector still shows an absolute 0
I have also held the detector over the top of the cell in the hood - still a reading of absolute 0
The thing is - I KNOW that HCN is gassing out of solution once dissolved but it just is not ROARING off & with the VERY good air flow I have though the hood the detector has not registered/indicated any HCN what so ever at any time in those first three days of this electrowinning project
This kind of made me wonder if the detector was actually even working
So how & "why" did I set the detector off
The other thing I have been doing is pouring the spent electrolyte after running the cell to win the gold into a couple 5 gallon buckets - with lids - which I then set on the floor "directly" under the hood
When I empty the cell I set the 5 gallon on the stool directly in front of the hood - take the lid off & pour the spent electrolyte into the bucket - & again at no time did the detector hanging in very close proximity of the hood face indicate anything other then an absolute 0
The thing is - I KNOW these solutions are in fact gassing off HCN & so HCN MUST be trapped in the head space of those buckets with the lids on them & with the detector never showing anything other then an absolute 0 it made wonder if the detector was even working
So - when going to empty the 5th run of the cell this time I decided to actually hold the detector in my hand when taking the lid off the bucket - when I take the lid off I do it by tilting the lid off the bucket so it opens towards the face of the hood - & this time with the detector actually in my hand when opening the bucket the detector "instantly" went off - so I took the 3 steps back out the door of the room with detector & lid in hand
Looking at the detector showed a reading of 24 PPM & once out in the fresh air it took the detector about a minute & half to wind back down to 0 - at which point I went back in (now knowing that yes the detector works) to see if there was any indication of HCN - absolute 0 including holding the detector over the now open bucket
So what is the moral of the story - at every point in the process - after dissolving the CN salts HCN is being produced - but - I have also put in place a fume/gas extraction set up (hood) that is keeping the production of HCN at VERY SAFE levels within my working space
Kurt
kurtak
Well-known member
I am sorry but I have to disagree & in fact absolutely disagree
Why ?
Because a second person is NOT going to tell you anything more about what is going on then the person that is working with the CN
In others words - that second person is NOT going to know there is a problem until he sees you laying dead on the floor - IF (the BIG IF) you should produce lethal levels of HCN
And that is because nether you (the person working with the CN) nor the second observer have any idea of what levels of HCN is being produced if/when HCN is being produced - so the second person simply is not going to know there is a problem until he sees the worker laying dead on the floor
That is where (IMO) a detector is important - these detectors are designed to VERY QUICKLY detect HCN at LOW safe levels for the very purpose of giving you FAIR WARNING to back away & to do so before the HCN reaches lethal levels IF (the BIG IF) levels are building to lethal levels
A second person is not & will not know that until he sees you laying dead on the floor
The only purpose a second person would have is to make the call for someone to come & pick up the dead body
Kurt
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An interesting take on the subject.
But cyanide is such a fast-acting poison that it might not give you any chance to react.
Safety is a layered undertaking, starting with basic equipment and working practices but should always finish with the worst-case scenario.
Not just considered, but rehearsed at least a few times so it sticks in everyone's mind.
Columbia University has researched the subject quite well, and I feel more confident using their recommendations than I would have without them.
However, intravenous supplies they recommend are unavailable without licensing in the UK.
There are circumstances that make a second person impractical. For one, a lot of smaller refiners work alone or in a very small shop. A second person, when the work only requires one person, just isn’t practical. If that is the case, as it is with Kurt, $400 for a detector is a bargain.
Plus Kurt is right, a second person, an observer, will only serve to drag out the body after the fact or even worse double the body count.
I come down on the side of knowing the hazards, designing the place properly, and a detector if there is enough potential for more CN work.
Plus Kurt is right, a second person, an observer, will only serve to drag out the body after the fact or even worse double the body count.
I come down on the side of knowing the hazards, designing the place properly, and a detector if there is enough potential for more CN work.
Haha that pretty much sums it up.
Back in the day I ran a large electroplating shop in a factory that manufactured electrical connectors from raw material to finished product. The plating shop had 750
gallons of Silver cyanide baths, 300 gallons of gold cyanide baths, plus copper cyanide plating and cadmium cyanide plating. A lot of cyanide. Plus the preferred way to strip Gold was cyanide peroxide, also known as bombing. And it is called bombing for a reason, look it up! https://www.finishing.com/51/98.shtml
The plant had about 500 employees so there was a health care professional there all day. When I arrived I insisted the nurse, as we called her, be trained in giving IV treatments specifically to administer the antidote for cyanide poisoning which, I believe to this day is still administered by IV.
Because we had good exhaust on all of the baths and everyone who set foot in that shop was trained about both the safety with acids and the dangers of cyanide, we never had an episode of cyanide poisoning. The training was repeated every 6 months so they knew we were serious.
gallons of Silver cyanide baths, 300 gallons of gold cyanide baths, plus copper cyanide plating and cadmium cyanide plating. A lot of cyanide. Plus the preferred way to strip Gold was cyanide peroxide, also known as bombing. And it is called bombing for a reason, look it up! https://www.finishing.com/51/98.shtml
The plant had about 500 employees so there was a health care professional there all day. When I arrived I insisted the nurse, as we called her, be trained in giving IV treatments specifically to administer the antidote for cyanide poisoning which, I believe to this day is still administered by IV.
Because we had good exhaust on all of the baths and everyone who set foot in that shop was trained about both the safety with acids and the dangers of cyanide, we never had an episode of cyanide poisoning. The training was repeated every 6 months so they knew we were serious.
