filtering acid vapor

[masoodstar]

Hi dear friends

 

I work with sulfuric acid and 0.75HNO3+0.25HCL for a gold refining project. The main problem is the huge amount of those acid vapors in the place.

 

Did any body have the same problem?

 

Could we get and filtrate the acid vapor with the activated carbon?

 

Any related help is really appreciated.

 

Thanks all

[studiot]

You should not be working with those substances unless you know what you are doing, including proper strorage handling and other safety requirements.

 

It is a legal requirement in most, if not all, countries.

 

Since you are working with gold you can obviously afford to pay a proper rate for a competent technologist to advise.

Edited May 26, 2015 by studiot

[John Cuthber]

You should not be working with those substances unless you know what you are doing, including proper stroage handling and other safety requirements.

 

It is a legal requirement in most, if not all, countries.

 

Since you are working with gold you can obviously afford to pay a proper rate for a competent technologist to advise.

Yeah, everyone who works with gold is a millionaire.

http://www.okinternational.org/mining

Apart from the fact that the profit margin on a lot of gold extraction is minimal.

 

This might be helpful.

http://en.wikipedia.org/wiki/Scrubber

 

Studiot's right about getting proper help designing it.

[masoodstar]

Thanks all

 

Actually we work with these substances under strict conditions, so, no worry about it.

 

The only problem is that we're using such simple fans to transfer the odors and fumes into the air! Which is seemed to be really unreasonable!

 

So we're decided to use some filters to help the health of the air.

 

We prefer using dry filters.

 

So any help is really appreciated for these kinds of vapors.

 

Thanks again for the replies.

[Mordred]

In all honesty carbon filters are great for most gases. On liability issues you need to seek professional chemical/gas filtration companies.

 

I recommend asking other companies and similar industries for advice and direction.

Any forums advise is meaningless in a court regardless of how diligent.

 

Seek professional, reputable and accredited help.

Reputable third party companies is a highly valuable resource.

Edited May 27, 2015 by Mordred

[MigL]

Both North and Scott have organic/acid acid cartridges for respirators.

If an engineering solution rather than PPE is more desirable, then a scrubbing system that sucks away the vapours and passes them through a NaOH solution would be the way to go.

[pavelcherepan]

MigL, just a note that when safety management is concerned engineering solution is always more desirable than PPE. Eliminating the hazard altogether is even better, but PPE should only come in play when all other measures fail or otherwise impossible to implement.

[MigL]

Definitely agree.

But as we don't know the size and scope of the OP's operation, maybe not feasible or financially appropriate.

[John Cuthber]

Definitely agree.

But as we don't know the size and scope of the OP's operation, maybe not feasible or financially appropriate.

In the UK those "excuses" wouldn't stop you getting prosecuted if you relied on PPE rather than LEV.

As studiot said at the outset, if you can't do it safely, you shouldn't do it at all.

[studiot]

Thank you John and pavel for your support but my short post was obviously not completely clear.

 

You don't only have a duty to think about normal and correct operation you also have a duty to think about a failure situation.

 

When something goes wrong it is too late to start trawling the internet for help, free or paid.

 

You need emergency plans in place and immediate access to personnel with the correct knowledge and training to deal with any situation that might forseeably arise.

[MigL]

So if this is a 'two beaker' operation that the OP is using to reclaim an ounce of gold, he needs to implement a full scrubbing system ?

 

Boy, I'd hate to think what kind of construction you guys get up to when you use muriatic to clean your concrete drive.

[John Cuthber]

So if this is a 'two beaker' operation that the OP is using to reclaim an ounce of gold, he needs to implement a full scrubbing system ?

 

Boy, I'd hate to think what kind of construction you guys get up to when you use muriatic to clean your concrete drive.

I think that sort of comment is best dealt with by referring it to what (round here) would be the enforcing authority.

They have a list of bulldust; here's the relevant one.

http://www.hse.gov.uk/myth/myth-busting/2013/case140-risk-assessment.htm

[MigL]

Note that your equivalent to our Canadian Occupational Health and Safety Act only refers to companies, not individuals, John.

[hypervalent_iodine]

So if this is a 'two beaker' operation that the OP is using to reclaim an ounce of gold, he needs to implement a full scrubbing system ?

 

Boy, I'd hate to think what kind of construction you guys get up to when you use muriatic to clean your concrete drive.

The OP described the amount of vapours being produced as huge. Not sure where you're getting that this is a, 'two beaker,' operation from, whatever that's supposed to mean. If the problem is already bad enough that they need to employ fans - and even those aren't sufficient - I think it's fair to say that additional engineering controls are far preferred to PPE. As others have said, engineering controls should always be the first consideration when you are trying to minimise risk. How large that risk is and by how much it needs to be reduced comes down to context.

[pavelcherepan]

Note that your equivalent to our Canadian Occupational Health and Safety Act only refers to companies, not individuals, John.

 

Guys are working with hazardous substances and are working on gold refining which to me implies some monetary gains, so legally they should be registered as a business of some sort. And if they are registered as a business then all provisions of workplace health and safety regulations apply to them to a full extent.

 

Additionally, chemicals, especially such hazardous, should come with some form of material safety data sheet (MSDS) or product safety data sheet (PSDS) issued by the supplier. Such data sheet would contain most information on handling and safety procedures relating to a particular substance and information on hazards that can arise from using, storage and handling of the substance. So the first place I'd be looking to answer the question in the OP are MSDS's for acids in question.

 

Addendum: I had a look at EU safety data sheets and this is what I found for substances in question:

 

HCl:

 

 

 

By heating evolution of corrosive and toxic hydrogen chloride gas/aerosols. By contact with steel or aluminium and other metals highly flammable hydrogen gas. By contact with fire traces of toxic chlorine gas possible.

By contact with strong oxidants (bleaching agents, H2O2, HNO3, etc) evolution of toxic chlorine gas.

 

Sulphuric acid:

 

 

 

Technical measures : If user operations generate dust, fumes, gas, vapour or mist, use process enclosures, local exhaust ventilation or other engineering controls to keep worker exposure to airborne contaminants below any recommended or statutory limits.

Personal protection measures

Respiratory protection : Use a properly fitted, air-purifying or air-fed respirator complying with an approved standard if a risk assessment indicates this is necessary. Respirator selection must be based on known or anticipated exposure levels, the hazards of the product and the safe working limits of the selected respirator. Recommended: Combination filter, e.g. DIN 3181 ABEK or selfcontained breathing apparatus (SCBA)

 

Nitric acid:

 

 

 

Exposure limit values :

The following values apply to nitric acid (HNO3) vapours

EU OEL 2000/39/EC

Recommended values;

STEL 2.6 mg/m3 (1ppm) (2006/15/EC)

Engineering measures : Local exhaust ventilation where appropriate.

Provide safety showers and eye washing facility at any location where skin or eye contact can occur.

Edited May 28, 2015 by pavelcherepan

[MigL]

I do work with fuming Hydrochloric and Sulfuric ( not nitric however ) and am well familiar with their MSDSs. The impression I got from the OP was that it involves a small scale or temporary operation. Heck, even a beaker of fuming acid will produce enough fumes that cannot be evacuated by a fan, so that is no indication of the scale.

Note that all workplace risk mitigation ( I know EU is more strict than NA ) recommends the following...

1-Elimination of risks through process change.

2-Reducing risk through engineering controls.

3-Reducing exposure through Personal Protective Equipment.

...in order of preference. But nowhere does it say you cannot, or must not, use the third option.

 

And this is exactly what I stated in post #6 before everyone jumped on me.

Edited May 28, 2015 by MigL

[hypervalent_iodine]

I do work with fuming Hydrochloric and Sulfuric ( not nitric however ) and am well familiar with their MSDSs. The impression I got from the OP was that it involves a small scale or temporary operation. Heck, even a beaker of fuming acid will produce enough fumes that cannot be evacuated by a fan, so that is no indication of the scale.

Well, exactly. There is no indication of scale. This is why I found your assumption a bit odd. Admittedly, I also made assumptions on the scale based on impressions I got from the OP. Regardless, it's probably not a great idea to make recommendations about safety precautions on the basis that you think they are doing things on a small and temporary scale, when you don't actually know that to be the case. It's better to be over-cautious than under.

 

Note that all workplace risk mitigation ( I know EU is more strict than NA ) recommends the following...

1-Elimination of risks through process change.

2-Reducing risk through engineering controls.

3-Reducing exposure through Personal Protective Equipment.

...in order of preference. But nowhere does it say you cannot, or must not, use the third option.

 

And this is exactly what I stated in post #6 before everyone jumped on me.

 

 

I'm not sure that anyone has said not to use PPE. You should use PPE regardless of how well ventilated the room is, etc., when performing experiments such as this. Before you get to this stage however, you should always investigate ways to change your methodology to reduce risk and install necessary engineering controls (as dictated by circumstance / context). You should not be using PPE in lieu of those safeguards, you should be using it in addition to them. Your post seemed to suggest that you were not of this opinion and I believe that is what people were responding to in your comment. It's quite possible that this was a mis-interpretation of your words, though this is certainly what I took away from reading them.

 

OP: to echo others, your best bet is to get a professional to take a look at your operation and advise. It's hard to know exactly what you should be getting / doing without a lot of specific information. You should probably halt what you're doing until you have this sorted, however. If you haven't already gathered, using PPE as your primary safety net is a less than ideal way of going about things.

[John Cuthber]

Note that your equivalent to our Canadian Occupational Health and Safety Act only refers to companies, not individuals, John.

Note that the 1974 health and safety at work etc act does not just refer to companies.

That's what the etc bit is about.

but it's hardly the point, the OP talks about "we work with these substances" ad so on implying that there's several of them, not just an individual.

And, even if it was just a bloke doing it for kicks and giggles in his back yard, miles from anyone else, the advice is still sound.

It's still a good idea to reduce the cause of the problem if you can. It's still better to control it at the source rather than to try to use PPE and, if you are stuck without an alternative, you still need care in choosing the protective gear.

Why do you think that's not good advice for an individual?

Do you think individuals are more expendable or something?

[MigL]

You're right Hypervalent, maybe I did misinterpret the OP.

 

However, John's impression of my view...

"Why do you think that's not good advice for an individual ?"

...is also misguided.

 

He should re-read my post #6.

I've never said PPE is preferable to controls.

 

I am on the Joint Health and Safety Committee at my workplace and have had Occupational Health and Safety training.

And while the statutes do 'cover' individuals, John knows that enforcement would be a nightmare.

When was the last time he did some work on his roof ? Does he have an engineered anchor to tie off his fall suppression harness to ?

 

I am also exposed to liquefied Phosphine gas ( approx. 700 psi ). When it oxidises in air, it doesn't just burn, it explodes.

I'm also on the Emergency Response team ( single, no kids, so expendable ? Just kidding ) and have seen fires where the city's Fire Department is afraid to come into the plant. But we are well trained, aware of the hazards, and have successfully dealt with them ( with absolutely no injuries or major damages ).

 

And so, yes, there are circumstances where PPE is the only option.

It is usually the case for firefighters, policemen, or even astronauts.

( occupational health and safety, and the right to refuse unsafe work, doesn't even apply to firefighters and policemen )

Edited May 28, 2015 by MigL

[John Cuthber]

"When was the last time he did some work on his roof ? Does he have an engineered anchor to tie off his fall suppression harness to ?"

A few years back

And, because I know about that sort of thing, the job was scaffolded and, yes, it was tied properly.

 

My employer doesn't like me to talk about work on what might get called "social media" so I can't say who it is, but the lab I work in does some interesting stuff.

​The local fire services on record as saying that, in the event of a fire they will seek to rescue anyone and then " stand back and watch the fireworks".

I'm a trade union safety rep and I have been for a couple of decades or more. Among other things that means I'm fairly well aware of the law here.

And the hswa etc act does explicitly protect those individuals put at risk,whether they are employees or not. And it does apply to individuals if they are self employed (though our insane Prime minister has decided to do away with that.)

 

As for

"occupational health and safety, and the right to refuse unsafe work, doesn't even apply to firefighters and policemen )"

It does here in the UK.

http://www.hse.gov.uk/services/police/application.htm

 

But, again, it's nothing to do with the case.

It's pretty unlikely that we are talking about anything but a small business.

(it would be useful if the OP let us know about that)

But it hardly matters. While there are occasions where PPE is the only option (the first option with deep sea divers or astronauts is to see if you actually need to send a person rather than a robot), it's still not the first thing you should consider. PPE is a very much weaker solution than engineering the problem out (and it's just swapping one problem for a whole series of other problems like suitability,maintenance compliance etc).

Of course, unless you believe that this guy is working on the moon or for the armed forces, it's a complete red herring. (Though I did do some interesting work for the police/ forensic science techs- I was checking to see what chemical hazards they could be exposed to if they were collecting evidence in clandestine drug manufacturing labs- the first thing I did was a lot of searching for "meth cook" recipes. There are tons of them)

 

It also doesn't matter if it's a multi million dollar factory or two blokes in a shed; the first thing you need to do is assess the risk and take precautions commensurate with that risk.

 

So, let's have another look at what you said

"Both North and Scott have organic/acid acid cartridges for respirators."

Yes those suppliers (and others) provide some good kit.

But it's not possible to say for certain if it's the right response.

A respirator is great for putting on in a hurry so you have a few minutes to turn off the power and open the windows (or turn it on and close them - depending on the circumstances*) before you walk away.

But it's a crappy way to deal with day-today exposure to acid gases.

So, unless you think the OP has a catastrophe on his hands and has decided to address it by posting a question on a web site, it's probably not the right approach.

And you seem to have forgotten to mention face-fit testing so, there's no way of knowing if the kit would work. Shucks! you didn't even ask the OP if they have a beard.

"If an engineering solution rather than PPE is more desirable, "

An engineering solution is practically always more desirable- to the extent that some legislative systems we know about mandate that approach as the first choice for dealing with a hazard you can't eliminate.

"then a scrubbing system that sucks away the vapours and passes them through a NaOH solution would be the way to go."

No it's not.

​You don't use NaOH if you can use something less hazardous- like Na2CO3 (which also has the merit of being cheaper).

 

* according to the documented procedures for the type of incident you are dealing with- if the event isn't covered by the risk assessment- you already failed before you started.

[MigL]

So while we may disagree as to using Sodium bicarb or sodium hydroxide in the scrubber ( safety vs efficiency ) you do agree that I mentioned that a scrubber system was more desirable ?

 

Oh and I hope you used the right kind of scaffolding when working on your roof. The kind with barriers and kickplates all around.

And IIRC, at least here in NA, you still need a harness above a certain height.

 

And what if it was a small job like getting you cat out of the tree in front of the house ?

Would you rent scaffolding to get it down the next day ?

Would you just tie off a ladder as securely as possible ?

Or would you just climb the tree ( sorry I don't know your age ) ?

 

And I wasn't aware that firefighters and policemen had the right to refuse unsafe work in the UK.

Must make things interesting ( and a little frightening ).

Edited May 29, 2015 by MigL

[John Cuthber]

I'd assess the risk/ benefit analysis of climbing the tree.

 

For a cat I might not bother. (AFAIK no cat skeleton has ever been found in a tree). For the child of the pretty widow who lives down the road, I 'd take the risk.

 

Since I don't own a ladder that would get into a tree, I'd probably call the RSPCA or maybe the fire service. They have the equipment and training.

Yes, it was the right scaffold- not least because putting up the wrong one would be illegal.

No, I didn't use a fall arrest harness, but I did use a rock climbing one.

 

Since it's the water that does the scrubbing in the first instance, carbonate (not bicarbonate which would also work, but be more expensive) would work just as well and be safer.

Edited May 29, 2015 by John Cuthber

[masoodstar]

Please consider that we have strict rules on working with such materials. For this we're working on an efficient filtering system.

 

Anyone have had any related issue in the industry? How this could be really solved?

 

Unfortunately all the members are just talking about the rules on working with such applicable acids in industry. Let's accept daily working with these acids and try to provide a good solution to my problem. Actually just an article about the water scrubbers was useful during the iterative posts

 

BTW, any other nice solution e.g. adsorbers is really appreciated.

 

Thanks for your cooperation