Sodium metabisulphite Vs. sodium metabilsulfite

[Anonymous]

First I would like to say thank you to everyone who has contributed to this forum. I have been reading and studying the wealth of info here for almost a year as well as Hokes book.

My first test went as follow: I dissolve .3 grams of 23K gold leaf using the HCl-Clorox method. The result was a nice yellow colored solution just like the examples in the forum. To prove my findings I created stannous clouride using Tin solder in HCl. when tested my solution turn purplish/Black. That proves that the gold is there if I am not mistaken. Next, I purchased Sodium Metabisulphite from a wine making store. Dissolved approx .3 grams in hot tap water. I added the SMB to my gold solution and no precipitation fell. I notice that most postings on this site spell MSB as sodium Metabisulfite not Metabisulphite. Is there a difference. After many google searches and cannot find a awnser. I know there is a difference between Phate and Phite. Any help you could give me would be much appreciated. According to LaserSteve there is no need for Urea when using the HCl-Clorox method. I am at a loss.

Rob

 

[4metals]

Metabisulfite and matabisulphite are the same thing, Americans would spell it fite but Brits and Canadians might lean towards the phite spelling. You are using the right chemical but at .3 grams probably not enough. The reducing agent has to overcome the ability of the solution to re-digest the gold and you just didn't use enough. I'm also making an assumption that metabisulfite purchased in a wine making shop is the same strength as technical grade material, that is no fillers. If you add more the gold will drop.

 

[Anonymous]

Thanks for the info. I will give that a try. Would it be neccesary to disolve it in water first or could I just add the powder to the gold solution?

 

[4metals]

It works better if it's dissolved, as a powder it will work but more is wasted because the SMB fizzes and reacts at the surface of the acid and doesn't actually get into the acid to do its thing.

 

[Oz]

While you are correct that urea is not needed when using the HCL-Clorox method you do want the “free” chlorine (Cl2 gas) removed from your solution before precipitation with SMB. This is not a big deal as a quick boil of your solution or letting it stand for a few days is all that is required.

 

[Anonymous]

I followed the recomendations to add more SMB and it did drop. thank you so much for your help to all of you. I did not boil of the cl though. What is the benifit to removing the chlorine? Just when I thought I understood the process I get a new wrinkle. :lol:

 

[qst42know]

The chlorine does the dissolving and will redissolve the gold until it is consumed or dissipated by sun light, heat, or time. Or you must add additional SMB.

 

[Anonymous]

That make perfect sense. I should have thought of that myself. How do I know when all the chlorine is gone?

 

[qst42know]

When the gold comes down. 8)

 

[Anonymous]

one last question. If I can boil out thye chlorine or let it sit for a few days and allow the gold to drop on its own. What is the benifit of using SMB. Just to speed up the process?

 

[markqf1]

The gold will not drop out on it's own.
It must be "dropped out" with a precipatate such as smb.

Hoke?

Mark

 

[Noxx]

No, I am solidary and I spell it with an «F»

 

[rustbucketguy]

I realize this is an old post, but I want to throw in my 2 cents worth (and I did read the rest of the thread). Whatever stage you were at, if the addition of the Chlorox was fairly recent, the mix will be rich in hypochlorite which is a powerful oxidizing agent and is the chemical which makes the gold dissolve. Hypochlorite is not very stable and it is destroyed by working on gold, by sunlight, with time, and when exposed to air. That is why most instructions call for replenishment of the Chlorox to maintain a slight chlorine odor. SMB is a powerful reducing agent, therefore, the first SMB added will react with any hypochlorite remaining and then the SMB will start reacting with the gold chloride. So, the amount of SMB required in any particular batch will depend on how much residual hypochlorite exists, and how much gold chloride is present. Either plan the SMB addition when there is very little hypochlorite remaining or add extra SMB. Most of the excess will go away if you let it set overnight. Remember that SMB has a shelf life once it is dissolved. It also has a shelf life if it gets damp. Lumpy SMB may not work at all. If you get a sulfur odor when you dissolve it, it is probably OK (the SO2 that gives the sulfur odor is actually the chemical that is doing the chemical reaction to reduce the gold chloride and make it drop)

 

[leavemealone]

And 6 months later it's revived....lol.

 

[butcher]

rustbucket whats your background, you seem to understand this well.