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Techniques for Collectorshydrofluoric acid
31st Jul 2006 07:28 UTCAlbert Russ Expert
31st Jul 2006 10:19 UTCJolyon Ralph Founder
There may be people who can help you with your issue privately, but this is not the place to give out information on the use of HF.
Jolyon
31st Jul 2006 12:41 UTCDaniel Russell
You don't have to swallow hydrofluoric for it to cause injury or death. Because it is a lovely small molecule, it can be absorbed directly through the skin, and the vapours are absorbed directly through the lungs. When absorbed through the skin, it not only causes painful burns but also acts throughout the body to bind with calcium. This causes damage to the bones, but more importantly, makes calcium unavailable for critical chemical reactions in the body. One result can be heart failure.
A lethal dose of hydrofluoric acid can occur when as little as 2.5% (about the size of your hand) of the body's surface is exposed to concentrated hydrofluoric acid. You would be suprised at how little an amount of hydrofluoric acid is necessary to achieve that exposure. A geological lab technician in Australia splashed some hydrofluoric acid on his upper legs, providing exposure to an estimated 9% of his body. They amputated one leg after 7 days, and after 15 days he was dead of "multi-organ failure".
We all suffer from the (sometimes subconscious) "it can't happen to me" syndrome. But it *can* happen and it *has* happened.
31st Jul 2006 15:08 UTCAlan Plante
I hope that Daniel's post has made you understand why HF is considered to be a "lab-only" chemical, not to be used outside of a properly equipped lab, and most certainly not by people who are not trained in it's use.
You know, you can sit on a rock and toss a pint bottle of nitroglycerine back and forth between your hands day after day and not get killed by it - might even think the stuff is safe to handle. But just drop the bottle once...
HF is MUCH more dangerous than nitro - because you don't know that it is killing you while it is.
Anyway, if you are going to continue to try to use the stuff, please let us know where to send the flowers and charitable donations in your memory.
Seriously
Alan
31st Jul 2006 15:44 UTCPhil B.
Albert: don't use sulfuric acid either! The only acids I use are hydrochloric 10% with special acid gloves and 5% acetic acid (white vinegar). Dont mess with quartz...
remember to DISPOSE OF THE ACID PROPERLY!!!!!!!!
Phil.
31st Jul 2006 15:45 UTCPeter Haas
10% sulphuric acid is considerably less dangerous than 10% HCl !!
31st Jul 2006 16:08 UTCPhil B.
31st Jul 2006 16:14 UTCJolyon Ralph Founder
But not much benefit in using it to be honest, I bought some small bottles of Conc. sulphuric a few years ago and the only thing I've ever used it for is cleaning the toilet! Hydrochloric is far more useful.
Jolyon
31st Jul 2006 16:41 UTCZbynek Burival Expert
All chemicals are potentialy very dangerous if handled improperly. Its only about knowledge and safety, theres no secret about HF - just must be used properly by trained person and in equiped lab. Nothing to be done at home!
The truth is that all mineral acids can cause serious burns or injuries when handled improperly. One must know his knowledge and equipment limits:)
1st Aug 2006 07:36 UTCAlbert Russ Expert
1st Aug 2006 09:33 UTCAlbert Russ Expert
HCl- is a strong acid, it is almost completely dissociated as well as H2SO4. It is perfect for dissolving carbonates and thus cleaning their surface, and many other minerals. It could be the most general acid in mineral cleaning.
Safety: As far as splashing, HCl is not as hazardous as other acids because its only power is its full disociation, H+ ions always have a place to bond on live tissue. I do not reccomend on trzing it, even if rinsed immidiately, concentrated HCl may irritate skin and destroy its uppermost level. However, there should be no further damage to tissue if rinsing is not delayed. Unlike sulfuric acid, it liberates HCl gas that is both irritating and toxic. The release of HCl gas is proportional to the acid's concentration. If mixed with some strong oxidiying agents, there is danger of chlorine gas liberation.
HCl itself does not possess oxidizing properties and is sometimes mixed with hydrogen peroxide to achieve this.
H2SO4- again a strong acid just like HCl. It can be used with similar results but its major dissadvantage is that there are fare more insoluble sulfates than chlorides. Its properties are very much dependent on its concentration. Diluted H2SO4 is only a strong acid, just like HCl. As it becomes very concentrated to anhydrous (100%), it becomes a good oxidizing agent and extremely hydroscopic. It is in fact so hydroscopic that it destroys tissue as it draws water from it and reacts with many organic compounds so that these compounds release even more water. As a result, plant and animal tissue can become almost carbon like. The advantage of this is that for instance an inert mineral can be cleaned from excess fungus and organic material with concentrated sulfuric acid- actually the acid does not remove this stuff completely but due to the destruction it makes it is much easier to rinse and scrub off afterwards. A disadvantage of this property is that concentrated H2SO4 is very hazardous because it pulls water from tissue, even from organic molecules and oxidises and releases H+ at the same time. Therefore spills of concentrated H2SO4 on body are much more dangerous than HCl or diluted H2SO4. Sometimes tissue destruction is immidiate and severe.
HNO3- is an acid in low concentration similar to HCl but produces very few insoluble compounds. It has significant oxidising properties which become very apparent at high concentrations. At higher concentrations above azeotrope (over 65%) HNO3 not only becomes highly oxidizing but at over 80% is hydroscopic and reacts with water quite intensely. It is not as hydroscopic as sulfuric acid though. Like HCl, it liberates toxic gases (NO2 mostly) which is not only highly irritating but also poisonous. At concentrations around 80% and over, the acid is fuming vigorously and is very dangerous to deal with. 65% HNO3 small contacts or splashes cause yellow stains on skin that peel off within days if washed immidiately. Fuming 80% acid or more causes severe burns on skin immidiately that are very different from the commercial concentrated 65% and differences are apparent even if washed immidiately. I had one bad experience in such. HNO3 is also very dangerous with many organic compounds at such concentration as vigorous niotration, oxidation or ignition can occur. HNO3 at such concentrations is not practical for mineral cleaning due to its dangers while better results can be obtained when carefully heating deluted acid.
HF- hydrofluoric acid is not a strong acid (it is much less dissociated as an aqueous solution because the hydrogen bond is too strong for free ions to form readily). Acid strength is defined in its dissociation in water, not in its other potentially hazardous chemical or physical properties. In fact, if HF was a strong acid, it would not penetrate tissue so well because H+ would attack tissue right from the skin sufrace, slowing the molecule's propagation. Obviously the undissociated molecule is very small which only benefits its fast penetration through tissue. Eventually it reacts with almost anything within the tissue, creating severe burns and tissue necrosis. At the same time, F- ion precipitates Ca2+ and forms insoluble CaF2. Drop of Ca2+ and Mg2+ in blood levels, called hypocalcemia and hypomagnesia in severe cases proves fatal because of their importances in many physiological processes including heart muscle functioning. Hydrofluoric acid is the only known chemical that effectively dissolves quartz, glass and other silicates. It is unfortunate because the only chemical possible is so dangerous. Glass can be attacked by hot concentrated phosphoric acid or molten NaOH or KOH, but the rate of attack is very slow and the results are very bad. I am not sure about quartz. HF, when concentrated enough, does not attack many metals and can be transported in steel tanks.
HOOC-COOH oxalic acid is best in removal of rust stains and selenite. It is a weak organic acid that bonds meny metals in very stable complexes.
CaSO4 for example is almost insoluble. Sulfates in general are extremely stable because sulfuric acid is a very strong acid which binds very well, and no acid is able to release sulfate ion into sulfuric acid and take its place. Usually weak acids that create salts can be released with a stronger acid. That's why carbonates are so easy to dissolve- H2CO3 is a very weak acid that can be substituted by almost any other acid and because it is not very stable, it decomposes and creates CO2 bubbles. HCl is a very strong acid but both HCl and HNO3 can be released if H2SO4 is applied on chlorides or nitrates, creating more stable sulfates. If we want to dissolve CaSO4, in a sense no acid can help us. Oxalic acid is one solution but not as an acid but as a complex-forming agent. Oxalic acid binds Ca2+ into a very stable complex, dissolving CaSO4, otherwise very difficult to deal with. At the same time, oxalic acid is poisonous because it binds Ca2+ in live organisms into complexes. Calcium is still present in an organism, but not a necessary free ion but a very stable complex that is useless. Hypocalcemia is induced just like in case of HF poisoning, only due to a different chemical process. Fe oxides in form of rusty crust can be removed by binding Fe into a soluble complex. It is strange that HCl and HNO3 are unable to dissolve a simple oxide of such a metal as iron. The problem is that Fe forms complicated oxides and peroxides that are difficult to attack with regular acids and are thus surprising insoluble. Oxalic acid and oxalates are unstable at higher temperatures and decompose into CO, CO2 and H2O. If there is too much iron oxalate on a specimen that does not go of, it is possible to heat up the mineral (if heat does not destroy the mineral itself), oxalate decomposes and the mineral, with reformed Fe oxides, can be repeatedly treated with oxalic acid. Because of thermodynamic instability of oxalic acid and its salts, one other danger arises. Termal decomposition releases carbon monoxide and this starts occuring once the acid bath boils. Therefore oxalate solutions should be heated carefully and never boiled.
Conclusion.
In general, it is important to note that each acid is a solution for a specific problem. There is no universal acid that dissolves everything and each acid is characterized by its specific set of properties. It is also important to note that concentration and temperature may change the acid's properties and abilities to achieve something exrtremely- a few percent off can seem like a totally different substance. Sometimes, acids must be even combined for example to dissolve gold and so on. It is important to know that each acid is usefull but in a different way- and each acid is dangerous but a different way. I ackgnowledge that HF may be the most dangerous but that's because it posesses unique properties that coincidently are not compatible with human body.
1st Aug 2006 15:27 UTCAlan Plante
We are so used to novices showing up here asking about the use of HF that we are pretty much programed to say: "Are you NUTS!" :~}
I'm sure you can appreciate the need for people to be cautious about giving certain types of info to people they don't know - especially when it comes to extremely dangerous things like HF. At one point, Jolyon had one or two people who were using HF, even though they were not trained and didn't have access to a proper lab, telling others here that it was just fine to use it for mineral cleaning, no problem... It was at that point that Jolyon instituted the present policy regarding the discussion of HF here.
Regards
Alan
1st Aug 2006 15:48 UTCBarry Flannery Expert
'' it not only causes painful burns '' This is untrue, the reason HF is so deadly, it doesn't burn, you don't even feel it until it is busy attacking bones-too deep to clean off with water!
Barry
2nd Aug 2006 02:24 UTCPaul L. Boyer
1) As mentioned above, hydochloric acid will release HCl into the air. If you are messing with concentrated acid, even a well ventalated area may not be enough to prevent you from getting a good whiff of the stuff. It burns, baby (I was using 12 Normal HCl). You really need air flow taking fumes away from you, or be sure it is reasonably dilute.
2) An old chemistry lab warning! When diluting acids, add the acid to water. NEVER add water to acid. Mixing water and acid releases heat. If you add acid to water, the heat is absorbed reasonably well by the water. However, if you add water to acid, the acid (being concentrated) will be on the bottom below the water, and the heat released can be enough to launch the water (and acid) right back out of the flask or cylinder. I saw it happen with sulfuric acid with water dumped on top, and we had bad acid rain.
2nd Aug 2006 07:39 UTCAlbert Russ Expert
3rd Aug 2006 15:51 UTCDebS
I have used oxalic acid in dilution to get rid of iron both on minerals and in toilets!
I have also used hydrochloric, a weakened variety sold at hardware stores for calcite, but I HATE even using it. I have always used it outside, never inside. And with a full face shield and in a locked but airy shed. I hope not to use it ever again.
3rd Aug 2006 18:21 UTCDaniel Russell
If you will google "hydrofluoric painful burns" you will see numerous citations on the painful burns that can be caused by hydrofluoric acid, including some case studies.
4th Aug 2006 22:57 UTCClaus Hedegaard
I have seen people in developing countries seriously hurt because they have used HF and not known what they work with and I know of numerous mineral dealers who are idiots ... careless idiots.
Fine with me that we do not dispense advise on working with HF as such, but allow my to put forward one piece of advise to those who fail to appreciate HF should not be used except under exceptional circumstances:
If you work with HF always use the gear mentioned in the MSDS, etc. and ALWAYS have a jar of calcium gluconate gel next to where you work. Before opening the HF, you check where that jar is and that the cap is not stuck. If you get HF, however dilute, on your body put on calcium glucionate gel immediately - only rinse if it is a major spill, calcium gluconate gel goes first. The calcium binds the HF and may (MAY!) prevent tissue damage.
When you've done that, then you call the ambulance.
Calcium gluconate gel is readily available in shops dealing in chemicals, safety gear and most pharmacies can get or make it. I have even seen mineral dealers selling it (mail me if you need an address).
Claus
12th Aug 2006 11:07 UTCBarry Flannery Expert
Hydrochloric Acid isn't that bad (at least at 10%) as I regularly use it when ever I can get my hands on it...
The only danger is if you spill some when it hasn't been diluted or if you accidently get a whiff of it while pouring but apart from that I find it quite safe but always have a nearby tap and plenty of basic substences ready.
Barry
3rd Sep 2006 23:19 UTCRichard Bielek
our common friend, Mgr. Kusik, has once used HF and since that time his finger is twice bigger. It is up on you to continue playing with hazards but it may happen that your mother will again remove the glaze from your WC. Anyway, I support your scientific approach and I am on your side while cleaning the minerals, including mines, with selected chemicals.
Your friend
Richard
4th Sep 2006 20:00 UTCPaul L. Boyer
http://www.mallbaker.com/Americas/catalog/msds.asp?searchdata=9563&searchbrd=B&language=E
4th Sep 2006 20:08 UTCPeter Haas
Barry was entirely right in saying that you don't feel it when it comes in contact to your skin - unless you get contaminated with a larger volume. The skin burns are the result of a necrosis of the tissue through which HF has penetrated. If you can feel it, it's too late ...
6th Sep 2006 23:26 UTCPaolo Malesci
1) DON'T USE HF (hydrofluoric acid)!
2) when you use acids use only commercial type and dilute slowly IN water to obtain maximun 10% concentration;
3) use gloves;
4) work in a well ventilated area;
5) have a bucket with sodium bicarbonate solution near you;
6) after this remember that acids are always dangerous (except for 5-7% acetic acid = vinegar).
8th Sep 2006 17:27 UTCPete Nancarrow
Having said all that, I concur absolutely that the only sensible advice concerning HF is that unless you are trained in it's use and are intending to use it in a laboratory equipped for it's use, don't even think about it! It's hazards are in a league apart from most of the common acids. Just about the only other compounds I ever worked with which came anywhere close to HF in 'scare factor' were phenol di-iodo arsine and saturated solutions of organic thallium salts.
Pete N.
8th Sep 2006 17:29 UTCPete Nancarrow
8th Sep 2006 23:33 UTCPaolo Malesci
I know that there are many horganic acids not dangerous and we eat someone very often but I've never seen someone cleaning a mineral with an apple, so is better to talk "acids are always dangerous"; trained peoples know risks and safety procedures for working with dangerous agents, but the others don't.
9th Sep 2006 03:03 UTCAlfredo Petrov Manager
9th Sep 2006 03:57 UTCMess O'Potamia
9th Sep 2006 12:53 UTCPaul L. Boyer
11th Sep 2006 15:58 UTCAnders
As for the strong inorganic acids (HCl, sulphuric acid), I would say they should be handle with great precausion and in most cases acetic acid or citric acid will give even a better results wich much less "nastyness". However, they are not at all as dangerous as HF.
... well in short stay of the HF
28th Sep 2006 17:39 UTCMichael
28th Sep 2006 19:10 UTCAlfredo Petrov Manager
29th Sep 2006 05:19 UTCDon Saathoff Expert
29th Sep 2006 11:31 UTCMichael
I hoped that by increasing the temperature and extending the cycle time, we could get the same result but in a safer way. I think even 0.5% might work.
29th Sep 2006 13:49 UTCMichael
29th Sep 2006 16:52 UTCJolyon Ralph Founder
http://www.carwash.com/article.asp?IndexID=4230101
29th Sep 2006 21:49 UTCDon Saathoff Expert
30th Sep 2006 20:14 UTCDominik Schläfli
Dominik
6th Oct 2006 17:50 UTCRick Kennedy
I do have experience with HF, having worked at a research and manufacturing facility where we used truckloads (many of them) of 70% HF. We could not get near HF above a few percent without full acid gear on -- double gloves, apron or acid suit, rubber boots, face shield, respirator. HF exposures were rare and minor, so I do believe HF can be safely and effectively used, like any other dangerous chemical. However, it takes a world-class safety program, which we had. Your typical car wash does not.
A note of clarification about painful vs. not painful burns. HF burns are reportedly extremely painful if the acid is concentrated, say 50% or more. Below 20%, the HF is still extremely dangerous but the exposure is not painful until maybe 24 hours later. So a worker may think it was just water that splashed him, and then 24 hours later when the area becomes red and painful he may not even remember what caused it, and neglect to get the proper treatment.
Lastly, about diluting to a "safe" concentration... I would venture that any concentration high enough to be useful is still dangerous.
Rick
17th Jun 2007 20:56 UTCRock Currier Expert
By this time you have probably already done some HF/Quartz experiments. If not I’ll tell you that it takes a long time to do more than just etch the surface of quartz and for the first few hours it seems to do almost nothing, even concentrated material. My experience has been that it will not leave your quartz with a lustrous 'polished' exterior like it will leave on glass. I think there is too much fear mongering on this site about the use of strong acids and not enough balanced informed discussion.
Rock
10th Apr 2008 14:41 UTCG. Evans
14th Apr 2008 03:57 UTCMark & Linda Mahlum
Any help would be appreciated.
Mark
15th Apr 2008 09:19 UTCRock Currier Expert
If the coating of quartz on your hebnerite is very thin, ammonium bifluoride may do the cleaning you desire, but if it is of any thickness you will need to consider that perhaps only hydrofluoric acid will clean it properly. Most if not all of the hubnerite specimens from the Adams mine have been treated in HF to remove the natural quartz coating. Also most of the twinned ferberites from the San Cristobal mine in Peru, have also been treated in this fashion. I don't think you are going to find anyone on the board here willing to discuss the use of this acid for cleaning with you on line. If you can demonstrate that you know something about chemicals and proper safety procedures, contact them off the list and make a good clear case of what you want to do, I think there may be knowledgeable people here that may be willing to discuss it with you. The liability issues are considerable.
Rock
16th Apr 2008 03:27 UTCMark & Linda Mahlum
I'm neither qualified nor equipped to work with HF. That's the reason for my interest in ammonium bifluoride. I have some amethyst scepters with a coating of some kind of thin, but dulling silicate that would benefit from a cleaning in addition to my hubnerite. Additionally, I have some quartz after calcite rhombs to six inches that are coated with something that dulls them. Maybe. They may be etched by Hf from dissloved fluorite in that vein, I'm not sure. Trying ammonium bifluoride can't hurt. But what are the safety ramifications. I live at the end of the road in the San Juan Mountain foothills with plenty of open space, for what that's worth.
Mark
16th Apr 2008 04:11 UTCPaul L. Boyer
http://www.fap.pdx.edu/safety/hydrofluoric_acid/
16th Apr 2008 13:51 UTCDavid Von Bargen Manager
http://www.jtbaker.com/msds/englishhtml/a5628.htm
16th Apr 2008 15:58 UTCJesse Fisher Expert
In actuality, most coatings on mineral specimens are best removed by mechanical means, i.e.: an air abrassive unit. Yes, they cost money, but what is your health and safety worth? Unless someone is an experienced laboratory chemist, I would strongly recommend staying away from chemical cleaning and investing the money on one, or paying someone who has one to clean your minerals for you. A less expensive, thouth not nearly as effective alternative is a high pressure water gun.
21st Sep 2008 12:01 UTCTom Eden
I'd like to seperate the gold from its accompanying alloys (if any) and was told to
soak it in HNo3 for about a week. I was told the HNo3 would dissolve everything
except the gold. Is it really that simple? Or is there other things involved?
21st Sep 2008 18:23 UTCNH
One common method (Wohlwill process) of purifying gold is electrolytic, but you need pretty pure gold to start with, and gold chloride for the electrolyte.
I found a patent describing an electrolytic process using ammonium chloride as the electrolyte. If it works, this seems like the best method.
With either dissolving or electrolytic methods, the gold that you get out will be finely divided (powder) rather than a solid mass. In either case, you might also want to consider reprocessing the solution to recover silver and (if you process white gold) palladium. Silver can easily be removed as the chloride with the addition of sodium chloride solution or hydrochloric acid (remove the gold before adding any chloride, or you will get aqua regia, which will eat the gold; adding chloride will also precipitate lead, but this shouldn't be present to any large degree).
You might also consider cuppelation - a method that involves blowing chlorine gas over molten gold is used industrially, but would obviously be very dangerous and nearly impossible to do without specialized equipment.
25th Sep 2008 09:21 UTCRock Currier Expert
Thought you description of the various acids was quite good. Why don't you turn it into an article that we could post in the sticky message at the top of the Cleaning bulletin board? My experience in using HF on cleaning specimens is not extensive, but I will be glad to share what I know off line.
2nd Jan 2009 17:10 UTCMiko
What is the motivation behind all the authors who insist on publishing their own sometimes rational, sometimes irrational fears, INSTEAD of answering the original question, which had to do with
*) How to properly or effectively use HF in the structural & artistic transformation of Silicon Dioxide in the form of Quartz?
It seems obvious to me, and perhaps the original author, that HF is available to whomever seeks to find it. That being the case, it seems that one stern warning is enough, and I have faith enough in OSHA labels that this warning is already apparent to the buyer.
So do I really need 75 or more posts telling me about the dangers, some real and some made-up?
Sharing a humorous tale from my childhood - My sister was a chemistry professor when I was a child. I quickly, through charm enough of my own, grew to be very adored in the lab where she worked. The chemistry director befriended me especially when I said I always wanted a chemistry set for christmas. Instead of a lousy rusty-boxed set, I ended up receiving lab chemicals from the department, in boxes. I remember, probably to the ghastly vehemence of most of the fishwife posters here, playing with hydrochloric acid, sulfuric acid, ferrous cyanide, mercury (yes, the shiny liquid metal), along with countless others. The most delightful, now that I read this entire board, yes, was the infamous 'HF.' I'm not denying that I may be alive for very miraculous causes, however, I sit here wondering how many of the authors realize that one warning is enough.
I enjoy the memories from my past, I enjoy remembering the conversations I had with very intelligent and kind professors who taught the dangers as well as the beauties of science, so that I didn't act afraid, but was taught to think and act responsibly.
If you ever remember being a child, explaining what you know about a subject may prove the more appealing offering. One plays with minerals from curiosity, and even though some cats have unfortunate experiences, it seems like the original authors on this board are seeking to temper their curiosity with knowledge, not fear.
Miko
2nd Jan 2009 18:09 UTCFranz Neuhold
Yes, we need 75 or maybe more posts on this issue. Your post is an example for irresponsibility and arrogance, which can be misleading and very dangerous for other inexperienced people. Your main argument is that you are not dead. This does not convince me.
In my opinion it is careless and stupid to give HF to a child or use it outside a lab with the necessary facilities.
Best regards,
Franz
2nd Jan 2009 18:17 UTCDaniel Russell
If you wish to get nekked and roll around in plutonium, feel free. My ethical obligation (if any) ends with pointing out that its probably a very imprudent think to do. However, if I explain to you how to get plutonium, or how to roll around it in, the current legal climate can result in my facing potentially serious legal consequences. (I ain't saying its right, I'm just saying its so. I much prefer the simpler logic of Natural Selection... anyone who wishes to get their Darwin Award, the line forms on the right! Apply early, and apply often!)
You say "If you ever remember being a child, explaining what you know about a subject may prove the more appealing offering." This is precisely why harping on the safety issue involved in HF is important.
2nd Jan 2009 23:44 UTCClaus Hedegaard
> I'm neither qualified nor equipped to work with
> HF. That's the reason for my interest in ammonium
> bifluoride.
You need to take the same precautions with ammonium bifluoride as you do with hydrofluoric acid. Ammonium bifluoride is less reactive and less prone to produce fumes, but perfectly capable of causing tissue damage. I believe Rock is right and that this boards suffers of too much fear mongering with respect to chemistry.
But you do the right thing, ask for advice, when you don't know. Until you have a good understanding of chemistry and working experience with other chemicals, I recommend you for not use hydrofluoric acid, nor ammonium bifluoride.
That said, both have their proper use but more often than not, specimens are ruined. When you visit mineral shows, you invariably see Chinese and (particularly some years ago) Pakistani & Afghan specimens that got the good old hydrofluoric acid rinse ... and were completely ruined.
All the best
Claus
3rd Jan 2009 22:33 UTCAlysson Rowan Expert
Shall we say that I have a healthy respect for any soluble fluorides.
22nd Mar 2009 00:38 UTCAlfredo Petrov Manager
In household detergents? One hopes they are combining it with something else to make a final compound other than HF but, in that case, why not do it at the source, to eliminate the need for moving tons of HF along the public roads?
27th Mar 2009 13:43 UTCPeter Haas
(Confucius)
A newspaper article is certainly not the best source to learn something about chemistry. Whatever they wanted to say, they screwed it up.
It is true that HF is used as a raw material in the synthesis of particular surfactants (perfluorinated surfactants). Surfactants, on the other hand, are used in a whole array of different products, among which also are household detergents (note that a detergent is defined as a formulation that contains a surfactant). It is not true, however, that these particular surfactants are used in household detergents. Perfluorinated surfactants are chemically extremely stable and that there is no risk of setting fluoride free in normal use (deliberately burning them would not be a good idea, though). They are toxic, but for different reasons.
So, if you google for products that are manufactured from HF, you may find surfactants. If you google for the applications of surfactants, you probably find household detergents. Linking one to the other may appear logical (well, logics again !) if you don't know that "surfactant" is not a chemical classsifier but just refers to an obscure physico-chemical property that is met by hundreds of thousands of molecules.
HF is also used to produce hexafluorosilicate 2-, which may be used as a disinfectant. Again, hexafluorosilicates are very stable compounds.
17th Aug 2010 22:09 UTCRodrickez
17th Aug 2010 22:47 UTCAlfredo Petrov Manager
18th Aug 2010 03:48 UTCAnonymous User
Albert,even if you (obviously) are an experienced scientist,you'd better not use it.
I will answer randomly,since many replies are present.
HF burns can be noticed immediately or after a while.The burns are still burns,however,the acid,by absorbing Calcium can attack the neural system and thus the brain cannot realize the pain.
This is very dangerous,since the therapy is delayed.
Calcium gluconate gel is not enough in most case.One needs pills or even injections.It depends on the skin surface attacked.Gel is better than nothing,but not enough.
From my personal experience:
I have a couple of friends who used to use the acid.One of them used to use it with bare hands and no mask.He never had burns dipping his hand to the elbows inside the solution.He suffers from heart failure (probably due to the acid).He has been a miner and a person always living at a fresh air mountain site with healthy food and lifestyle.
The other one used to use gloves but no mask.He didn't notice the glove had a hole and he lost tissue to the bone of his finger.The doctors treated well the necrosis and the tissue was restored.However,no calcium gluconate was applied and he will have some organ failure in the future.
Note that both of them lead a perfect lifestyle!A smoker junk food eater with an office job will have much more serious problems!
Even if an accident doesn't occur,improper equipment will allow the acid to penetrate the skin and lungs and will cause health problem in the future!
All this for removing Quartz.
Even thinking financially,the use of the acid can provide you a good specimen that would be as expensive as 10.000 USD maybe?A laboratory can do it for you for some hundreds of USD.
An accident will cause you health problems that eventually will cost you much more!
I'm not sure if it right not to provide information on using the acid.There are people who won't believe until it happens to them and will use the acid.
Now,Albert,what do you mean by getting an interesting structure?seen specimens treated to remove a second generation and reveal the crystal color,but have you seen the result?Removing Quartz off Quartz?
You say you want to etch to get interesting structure.Do you want to get an etched crystal?What for?
With just a dip in low concentration (2-3 %? I have no idea) you will get the outer surface of the crystal with a look of surface cracking.
This is a fake to me.Removing Quartz off some other species would be ok,but Quartz off Quartz means both generations or crystals will be affected so this as valuable as polished specimen and even uglier!
Please post a photo,so we could understand what you intend to do.
-Kostas.
18th Aug 2010 13:07 UTCDan Fountain
18th Aug 2010 14:33 UTCDavid Von Bargen Manager
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD288458&Location=U2&doc=GetTRDoc.pdf
18th Aug 2010 14:42 UTCDan Fountain
Thank you for the reference!
-Dan
18th Aug 2010 16:30 UTCDonald Peck
18th Aug 2010 17:04 UTCJolyon Ralph Founder
If you are trained well and are carrying out work with the appropriate safety gear and equipment, even then we wouldn't advise you go near the stuff!
Jolyon
19th Aug 2010 03:14 UTCRock Currier Expert
19th Aug 2010 14:45 UTCRyan Eagle Expert
31st Aug 2010 05:38 UTCJeffrey Rank
31st Aug 2010 10:41 UTCDavid Von Bargen Manager
31st Aug 2010 17:12 UTCJohn Betts
The smoky quartz from the Smoky Bear Claim, New Mexico were all treated with HF/ammonium bifluorite in sequence to remove the outer quartz crust and maintain luster. Novices tend to oversoak these in the HF, resulting in telltale white cracks where the HF penetrated "burning" the quartz.
John Betts
31st Aug 2010 17:46 UTCAlfredo Petrov Manager
31st Aug 2010 20:31 UTCPeter Andresen Expert
Personaly, I'll never bring HF to my home, NEVER!
31st Aug 2010 21:05 UTCAlfredo Petrov Manager
23rd Mar 2012 15:17 UTCMary Lauren
6th Apr 2012 22:17 UTCTim Schafer
How difficult is it to set up a scrubber for the chlorine gas in a home lab, and what would I need? I have seen some pictures, and a couple in person, but these are large scale scrubbers at chip plants. Any advice, and or direction WILL be greatly appreciated.
I have stumbled upon a very sweet find, but the gold is so fine that mercury amalgamation is just not possible efficiently. The make-up appears to be quartz, alot of calcium (numerous caverns in the area), ridiculous amounts of mica, gold, visible copper and silver, and magnetics. I hope I have not violated your sacred forum with such queeries. Have a fantastic day!
7th Apr 2012 03:28 UTCAlfredo Petrov Manager
7th Apr 2012 22:58 UTCJenna Mast
They're quite fortunate to be across the street from the hospital!
11th Apr 2012 05:47 UTCTim Schafer
11th Apr 2012 09:22 UTCJohn Lindell Expert
11th Apr 2012 13:04 UTCAlfredo Petrov Manager
11th Apr 2012 13:05 UTCRock Currier Expert
We have a policy here on mindat not to tell people how to use HF because it is so dangerous. So unless you know how to work with this dangerous reagents we strongly discourage its use. Also it is pretty expensive. To buy a gallon of the stuff you will probably have to pay ninety dollars or more. Smaller quantities are proportionally more expensive per ml. If you really feel you have to work with this reagent you should find an old chemist or someone that has used it before and get them to help you and make sure you have all the safety equipment you need to work with it. If your gold is really fine and there is not much of it, it is possible that the acid might cost you more than the value of the gold you recover.
11th Apr 2012 13:07 UTCRock Currier Expert
11th Apr 2012 15:11 UTCM. Dante
We can take advantage of the fluorine ions nature to protect ourselves. When F- comes in contact with Ca++, it will precipitate as CaF2, which is fairly insoluble and harmless. Unlike the strong acids, such as HCl and H2SO4, HF is not fully ionize din solution. This means that throwing some baking soda on it will not neutralize it fully. In addition, NaF is not exactly friendly. Instead, have a solution of Calcium Chloride on hand, or any other highly concentrated source of Ca ions. Use this on spills, the Calcium will harvest the F-, and remove it from solution, which will shift the equilibrium of the HF:H+,F- in solution. You want to kill as much of the F- as possible, bind it up and get rid of it. When you shift the equilibrium, you can do this, carbonates will not react with HF fast enough for this to be useful or safe. Keep 2 bottles of calcium gluconate on hand as well. This is for the worst case scenario, that you spill some on yourself, use one bottle to saturate a roll of gauze and the other right next to you. Use this on any suspected spills without hesitation, remember that HF is painless.
Gloves and protective clothing is important, make sure your respirator is rated for HF. I would find a good, reliable respirator as well, don't go for the walmart special on this one. HF will diffuse across the lung very quickly, and good luck hitting your lung with Ca++ to protect it. HF gas will also come off the solution HF can diffuse across most gloves, so again, do your research and don't skip out on good safety equipment. Wear clothing that is protective, but also shows up liquid spills quickly. Above all, common sense is your best friend.
11th Apr 2012 15:28 UTCM. Dante
12th Apr 2012 00:09 UTCJenna Mast
The safety protocol for HF related hospital visits at school was to take the calcium gluconate gel with you and insist to the triage nurse that you needed to get to a shower immediately if they didn't understand the urgency of the situation.
In fact, personally I would have someone call ahead so they know you're coming. Diluted HF exposure is one of those emergencies that doesn't seem like it is.
12th Apr 2012 08:04 UTCRolf Brandt
12th Apr 2012 13:46 UTCAlfredo Petrov Manager
13th Apr 2012 05:11 UTCRock Currier Expert
Would you mind if I use most of what you say about using HF and put it in my article about cleaning quartz. Will give you credit, or course.
16th Apr 2012 03:25 UTCM. Dante
Good luck
23rd Apr 2012 13:02 UTCBart Cannon
Nothing does what HF can do.
However, I would never recommend its use by the general public.
If you must use HF be sure to tape a tube of calcium gluconate gel from Calgonate Corp of Rhode Island onto your wall. Not in a drawer somewhere.
Also use an eyeshield and plastic tongs during specimen transfer. You will lose your appetite if you see what a drop of HF will do to an eyeball.
If you use rubber gloves use only very heavy duty re-enforced ones. Thin gloves always have pinhole leaks, especially if they have been used to pick up quartz.
I haven't read all of the posts. Has anyone mentioned HF's more friendly sister, ammonium bifluoride ? It removes silica scum very nicely and attacks feldspar and fingertips with less aggression.
Bart
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 26, 2024 19:41:29