Saturation point of HCL / Bleach

[61 silverman]

Looking at the picture I posted the solution looks GREEN, It is yellow ,here is another pic of the same solution.. Mark

 

[samuel-a]

if you still have gold powder that is undissolved in that beaker, you can't filter the NaCl without loosing the gold that still undissolved.
what i would do, after boiling of the water is to add HCL to double the amount of the solution (some of the NaCl will go back to solution dou to the water in the HCL)
and add again bleach.

and continue the process periodically (boiling out the water to 1/3 of the volume or until salt is forming, add HCL +Cl) until all gold powder is dissolve.

you should dissolve with heat also.


steve, is this the process that you had in mind?

 

[lazersteve]

Mark,

Salt formation when boiling down HCl-Cl mixtures is very common. Once you see salt forming add just enough water to dissolve the salt before filtering and adding SMB.

When I get some free time I'll ponder the solubility limits of gold in HCl and clorox in more detail.



Steve

 

[JRH]

I have been doing some experimenting this week with fine placer gold and HCL/Clorox. I started with 6.6gms Au,8oz HCL and 2oz Clorox. The temperature here has been ranging from about 35degrees F at night to about 55 degrees high during the day. After 24hrs at the above conditions the solution was rich golden color with a heavy deposit of salt in the bottom of the reaction jar. I then added another 8oz HCL and 2oz clorox and allowed the solution another 48 hours. Again a thick deposit of salt had formed in the bottom. I filtered the solution, dissolved the salt through the filter with water and weighed the undissolved gold which came out to be 4.1gm remaining. It appears that it is taking about 8oz HCL/2oz Clorox per 1.25gm of gold at the given temperatures. I now have the solution precipitating and hope to prove a 2.5 gm yeild or at least close to it depending on the degree of natural impurities in the gold.

 

[Harold_V]

It appears that it is taking about 8oz HCL/2oz Clorox per 1.25gm of gold at the given temperatures. I now have the solution precipitating and hope to prove a 2.5 gm yeild or at least close to it depending on the degree of natural impurities in the gold.

Keep in mind, I am not familiar with the use of HCl and Clorox.
The numbers seem rather odd to me. If you use nitric and HCl to make AR, it requires less than 5 ounces of HCl to dissolve a troy ounce of gold. Some say as little as three ounces. Others say four ounces. Could it be that you require the addition of more Clorox, but not more HCl?

Harold

 

[Oz]

Harold,

I do not think it is a lack of HCl but the concentration of sodium making sodium chloride solids from the bleach (sodium hypochlorite). He is diluting the salt concentration with HCl and water may be better. A stir plate would make this a non-issue as the salt would not be covering the gold. The other is the solubility of the free Cl2 in solution if he is adding too much bleach at once adding sodium but losing Cl2 gas to the atmosphere. The cool temperatures help him as Cl2 gas is more soluble in a cool solution, however the oxidizing of the gold is faster at a higher temperature, but then you have again the Cl2 gas wanting to go out of solution. Chlorine can be a fine balancing act but it eliminates de-noxing. Practicing reflux of vapors solves much.

 

[JRH]

I should have added also that I am using a lightly sealed container for my reaction vessel. Basicly a quart container with a lightly screwed on lid. What I was trying to accomplish is allowing a controled release of the chlorine without being so tight that the top would blow off.

 

[JRH]

After having precipitated with SMB the dried and weighed precipitate came up to be 1.7 gm. That is a good bit short of what I exspected. I am going to drop with copper in the solution to see if any other PMs come down and then try a zinc drop and weigh the results of each.

 

[lucas77]

I was wondering based on my own mess up if a 50/50 mix would be alright and still retain my gold and also is their a perfect color indication of when its time to precipitate your gold for a high yield I just got into this hobby recently and looking for advice

 

[solar_plasma]

Much more information is needed to give you a satisfying answer. Here is a good point to start reading: Tips for Navigating and Posting on the Forum

The more you have read the better you will get at wording questions worth to answer, that more likely can and probably will be answered to your satisfaction.

Since you are new, those links might be of interest, too:

New to the board and want to ask questions? READ THIS FIRST

Hoke's book about refining

Hoke's book about testing

Guided Tour

Safety section

About the process using HCl and NaOCl you will find a lot of good threads if you type "HCl chlorox" in the search line. I did not understand your question, but it is probably answered on the first pages.

 

[Geo]

I should have added also that I am using a lightly sealed container for my reaction vessel. Basicly a quart container with a lightly screwed on lid. What I was trying to accomplish is allowing a controled release of the chlorine without being so tight that the top would blow off.

I understand this is an older post but I would like to reply to it now.

I would advise that you do not contain this reaction whatsoever. If the container seals due to some unforeseen reason, the HCl and sodium hypochlorite generates a huge amount of off gasses and could cause the container to explode unexpectedly. Not to mention the loss of your solutions but flying glass and chemicals is a hazard that is best to be avoided if at all possible.

 

[butcher]

HCl and bleach (sodium hypochlorite), NaClO (which is kept basic with NaOH sodium hydroxide), mixed together basically makes salt water NaCl, some chlorine, the acid is neutralized by the basic hypochlorite.

Normally when dissolving gold we have more HCl acid and add bleach sparingly, this helps to keep solution on the acid side, and with the chlorine formed in solution, there long enough to oxidize the gold so it can form gold chloride AuCl3 with the HCl acid.

Our acid is about 68% water 32% HCl (gas), the bleach is mostly water 94%, and about 6% hypochlorite, and when these react they create some more water from the reaction as the base neutralizes the acid making salt.
So when we do dissolve our gold we have the AuCl3 and NaCl salts diluted in lots of water, if we evaporate to remove an excess of chlorine gas we saturate the solution with these salts (normally you shouldn't need to evaporate unless overuse of bleach, as a good heat alone should be enough to drive off a moderate excess of chlorine, if you do concentrate and form NaCl (and a little bit of sodium chlorate), you can just add back some water to put these water soluble salts back into solution, as too much of these salts may hold some of your soluble gold chloride in their crystals (the yellow color coloring the white salts yellowish).

You will always form salts, but with enough water you just wont see them.