What can make the hcl/cl solution yellow before adding cl?

[bobinpasask]

publius

Excellent post on the respirators. I work them them all the time as a consultant and teach respirator use with Asbestos and Molds. Have seldom thought of their use much with a gas such as you mention, so even a 65 year old dog can learn new tricks.

I've never seen so much said about respirator use in such a short paragraph. Well done. You are the first person in milllions of written words I've read that has used the "engineering controls" wording and also in the proper context. Spot on .

People need to understand that engineering controls are mechanical or physical means of dealing with a problem (like the gases being relased that you discuss). Try a fume hood, work outside, even a fan blowing out a window and taking the gases with it. Anything to physically solve the problem BEFORE just standing there with a respirator on.

As a summary to your post. Please Use PPE as a last resort !

 

[publius]

publius

Excellent post on the respirators. I work them them all the time as a consultant and teach respirator use with Asbestos and Molds. Have seldom thought of their use much with a gas such as you mention, so even a 65 year old dog can learn new tricks.

I've never seen so much said about respirator use in such a short paragraph. Well done. You are the first person in milllions of written words I've read that has used the "engineering controls" wording and also in the proper context. Spot on .

People need to understand that engineering controls are mechanical or physical means of dealing with a problem (like the gases being relased that you discuss). Try a fume hood, work outside, even a fan blowing out a window and taking the gases with it. Anything to physically solve the problem BEFORE just standing there with a respirator on.

As a summary to your post. Please Use PPE as a last resort !

Thank you, sir! I try.

 

[Traveller11]

Yes, thank you for the words of wisdom, Publius. As well as the respirator, I was planning to use this process outdoors on a bench I have set up under the overhanging roof of my shop. As an added precaution, I plan to set a fan up beside me to create an air current. Do you think it would be best to have the fan blowing fumes away from the reaction or drawing fumes toward the fan?

I was also looking at a site describing the "Igoli Process" which was developed in Africa in an attempt to get small miners away from using mercury. The Igoli Process is essentially the HCl/Cl process although they have added a few things. Instead of allowing chlorine gas to go straight into the atmosphere, the leaching vat is sealed and the chlorine gas comes out of the vat through a tube on top of the vat. The tube is fed into another sealed container containing sodium hydroxide and, it is claimed, the chlorine reacts with the NaOH and becomes salt. It is unclear if the chlorine gas travels from container to container on its own or if it has to be drawn by vacuum.

The people behind the Igoli Process claim it is necessary to stir the concentrate occasionally though they do not say anything about adding air. They have an interesting filtering chamber for separating the pregnant auric chloride solution from the concentrate. It relies on low air pressure and one of their photos shows a fellow with a bicycle pump providing the pressure.

This company will build a custom leaching unit for the small miner or will provide the technical info free of charge. I wrote to them in Africa in February but have yet to hear back from them.

 

[Traveller11]

Traveller11,
I am adding this edit to this post, I made a mistake after posting it seems I glanced at electric's photo and thought it was what you were discussing, so unless your gold looks this clean disreguard this post, as it is based on very little pyrite or black sand in the gold.

From looking at the Photo, of the gold in your other post, you panned, it looks pretty well cleaned up, and I do not see where you should have much trouble refining it.

If it is indeed gold, which form the pictures appears to be, I have to admit, I did not read the thread, and just glanced at your picture before writing this, and am not sure if this is from a hard rock operation or placer gold.

My comments here are based on a very low content of pyrites, or black sand, and well panned free gold, and assuming placer gold although if cleaned well would not be terribly different.

As too high and Iron content (or other base metals) can mess up our solutions or process, and would need leaching before trying to dissolve the gold,

From glancing at the photo, yours looks clean.


I think I would roast it just for the heck of it,

If you can get nitric acid, then treat it in nitric acid wait a few minutes to see how it reacts, then add heating it to a good hot solution, the gold looks to be very fine, so if there is silver involved, a good stirring, you may get it into solution, some placer gold is 16% to 18% gold, and could have some silver to give you trouble dissolving the gold later, so for larger nuggets quartering the gold with silver may be needed, before treating in nitric acid, your gold looks so fine I think you may not have a problem there, but quartering may be necessary.


I do not think you will have too much pyrites in this, as if this gold was panned down to what looks to be fine gold in your pan, the pyrites are light and would have panned out way early in the panning process, the pyrites are so light they will pan away before much of the other dirt rock and sand, black sand,
Gold is very heavy (even very fine gold), and is the last to be panned away, the black sand can be iron oxide compounds magnetite and hematite, from looking at the picture of your pan I did not see much black sands, and as long as you do not have too much then you should not have trouble here.

Be careful not to breathe fumes from any processing, and extremely cautious of fumes from ores, as acids on some types of ore can emit extremely deadly gases.

I noticed your question about the hydrochloric acid and sodium hypochlorite, and I am wondering if you are trying to dissolve your gold in it without treating with nitric acid first, (if you do not have nitric acid you could try it), the gold if as fine as it sounds, it may go into solution with some heat, without pretreatment of nitric, but if You can get nitric I would use it, I would not skip the incineration step though.

I do not see where a very small amount of black sands, or even pyrite (especially as it seems you have cleaned your concentrates of these so well, would give you any trouble dissolving your free gold, the little bit of these may give up some iron in solution, but it is hard to break their bonds easily (iron sulfides, or iron oxides), and just a little of these in solution should not give you any trouble, even if some iron did entered into the solution.

You may find the gold will not dissolve easily into HCl/NaClO if silver content is high.

Also I mentioned Heating the solution, keep in mind that Chlorine will not stay in a hot solution very long at all, so you really do not need to get it too hot, and you may need to add sodium hypochlorite more often and in small amounts (the solution will work in room temperature but will just take longer), actually chlorine will stay in a cold solution much longer, (kind of a double edge sword).

Remember also when testing with stannous chloride for gold in solutions you will need to eliminate the free chlorine in the portion of solution that you are testing, or you may not see a reaction if the chlorine re-dissolves the gold in your test.

Also free chlorine needs removed before trying to precipitate the gold.

P.S. take Harold’s advice over mine any day, I cannot see your gold, and I am not sure Harold has looked at your photo, also it is kind of hard to tell what actually is in a picture,

Edit oops I wrote this post based on looking at the wrong gold or picture.

Well, I got my respirator mask in the mail with the cartridges for chlorine. I set my first experiment up outside my shop on a bench with a fan to blow fumes away from me.

The first thing I did was place a small amount of black sand (almost pure magnetite) in a plastic dish and cover it with Muriatic acid (HCl). The acid was a very light shade of yellow as it came from the bottle. After a few minutes with the black sand, the acid became a deeper yellow and then a dark orange. Going by the information in this thread, I would assume I am seeing iron being given up from the magnetite although, at a glance, the magnetite appeared to be intact.

I'm wondering if I should drain off the solution through a filter, wash the magnetite with water and try covering it again with Muriatic acid. Is it possible some iron was liberated but the remaining magnetite is stable? And, if I go to the next step, HCl/NaClO leach, will iron not dissolved by the HCl go into solution with the addition of NaClO?

 

[butcher]

I would have roasted off the sulfide getting it red hot grind and re-roast, the iron will leach yellow at first and also green, it will take several leaches (saturated with iron), these can be decanted and fresh acid used to dissolve more base metal, heat also helps but too much heat can form iron hydroxide, which will not dissolve in acids, I use 3% H2O2 also with the HCL, if you have gold it will be left as brown powder or minute flakes of gold.

Normally if gold is in black sand it is easier to just pan it out.