Dissolving Gold Foils with HCl-Cl:Comments

Post your comments and questions to the tutorial here.

Here's a link to the tutorial:

Dissolving Finger Foils

Steve

This is great stuff, fantastic system.

Here's a slight improvement or enhancement to your system?

Instead of pouring in the Chlorox, I filled a 50 ml burette with the Chlorox and adjusted the stopcock to let out a drop of Chlorox at a time.

Now I just take the Chlorox dripping burette and use it to stir the HCL while it's feeding in the Chlorox to the BOTTOM of the container versus the top. If you do this setup with a graduated cyclinder instead of a pot you could almost eliminate the escape of chlorine gas into the air.

Works great. I had the coffee pot with the HCL on a hotplate while doing this.

Steve,

Your suggestion is very good. This method is still under development and can definitely be improved upon. My main goal initially was to find a method for dissolving gold with common household chemicals and supplies.

I feel like this method is well suited to the hobbyist due to it's ease of use and the speed at which it works. The fact that it only requires two common chemicals is a big plus for people with minimal resouces. Coupled with the acid peroxide method of stripping the foils this method provides a nitric acid free system to gold refining. As an added bonus no urea is required.

You mentioned heating a coffee pot for this reaction. I've found that heat actually drives the chlorine out of the solution which reduces the solution's capacity for absorbing gold.

Thanks for the suggestion.

Steve

It would be interesting to check out the solubility of chlorine gas in water based on temperature.

P.S. I love the simplicity of this, no nitric, no urea.

Don't forget, it's also very clean on the precipitations! 8)

Steve

Chlorine gas is soluble in water.

Side Note:

The symbol Cl can cause confusion. In water chemistry chloride (Cl-) is from a salt, and is not the same thing as elemental chlorine (Cl2), which does not exist in tap water, even when bleach is added. This is another confusion - that bleach puts chlorine in water.

Bleach or sodium hypochlorite (NaOCl) added to water creates hypochlorous acid (HOCl). The HOCl partially breaks up into H+ and OCl- in a chemical equilibrium, as all acids do. The percentage of which it breaks up is dependent on pH. HOCl is a strong sanitizer, and OCl- is a strong oxidizer (bleaching agent). OCl- is unstable and can break up into Cl2 readily. HOCl is also broken down rapidly at low pH levels into H2O and Cl2 gas, which is why you should never mix acid and bleach. The reason is acids give up lots of H+ ions, which react with HOCl and to yield water and chlorine gas.

Just something i found. I don't believe we are dealing with a gas here so to speak ( that actualy breaks down the gold ). I think. :?:

Ralph

I cannot seem to buy Chlorex in the UK... :roll:

I guess I will have to find an alternative bleach that will do the same job!
Does anybody have any idea what I should be looking for?

I guess I can avoid the thick scented varieties?

Chlorox is only one of the U.S. brand names. The active ingredient, listed on the label, in all brands here, is sodium hypochlorite. The strength is usually 5.25% and it comes in 1 gallon jugs. Read the labels of the U.K. brands and look for sodium hypochlorite.

Steve,

Thanks again for all your hard work on making the videos!!!!

By seeing what is supposed to happen, and then watching it happen....That is really cool!!

I will add a few pictures, the first is the foils in a little HCl - Cl.


The second one is going to be after the foils have desolved!!

Thanks again!!!

Lew

Lew,

Great job! I find HCl-Cl to be very effective on all types of gold foils and powders. It's become a mainstay of my gold processing arsenal. I even use it on the gold filled shells after removing the base metals with nitric.

Steve

lazersteve said:

Lew, Great job!

Click to expand...

Indeed!

The color of your gold chloride solution speaks volumes about how nicely you did the preliminary work. Gold from that batch, properly handled, should be of extremely high quality.

Very nice job!

Harold

Beautiful!

Nobel Metals said:

It would be interesting to check out the solubility of chlorine gas in water based on temperature.

Click to expand...

Here's a chart which answers your question:


and another smaller scale solubility chart:

chlorine manual said:

Reactions With Metals
The reaction rate of dry chlorine with most metals increases rapidly above a temperature which is characteristic for the metal. Below 2500F (1210C) iron, copper, steel, lead, nickel, platinum, silver and tantalum are resistant to dry chlorine, gas or liquid. At ordinary temperatures dry chlorine, gas or liquid, reacts with aluminum, arsenic, gold, mercury, selenium, tellurium, and tin. Dry chlorine reacts violently with titanium. At certain temperatures, sodium and potassium burn in chlorine gas. Carbon steel ignites near 4830F (251 0C) depending on its physical form. .... Moist chlorine, primarily because of the hydrochloric and hypochlorous acids formed through hydrolysis, is very corrosive to most common metals. Platinum, silver, tantalum and titanium are resistant.

Click to expand...

By filling a chamber full of gold plated items and piping in dry chlorine gas at room temperature, followed by tumbling, one could theoretically absorb just the gold into the gas as auric chloride without affecting the nickel and copper base metals. :idea: . Tin would still be asorbed. The auric chloride formed could be recovered with water rinsing of the scrap after the dry chlorine is removed from the reaction vessel.

Steve

Seeing that the colder the fluid the greater the solubility of CL then is would seem best to keep the temperature of the HCL-CL mix as low as is practical? Hence the reason for adding the Bleach in small amounts.

I got a chance to add the SMB.

I first added water to dilute, then added the SMB(I never realized that you should mix it in water before you used it).

The cloud in the container was really nice to see!

Thanks again for all the help here on this forum, I don't think I would have made it this far alone!

Lew

PS I'll add a few more pics as I am able, thanks for the support!!

Steve this is great I have about four grams of some beautiful gold from your methods and plenty more to do so I just wanted to say thank you very much for your help and support my question is how much smb do you use in relation to water what would be the ratio. or maybe my question is how much smb do you use in relation tothe au-cl

If I am not mistaken you use a little more SMB than you expect to have gold.


For example if you had 4 grams of gold foils you would want to use a little more than 4 grams of SMB to drop the gold..

Just remember to always test your solution for more gold before you move it down the line!


Good luck!

It really is cool to see it happen!!!!

Lewis

When I see, visually, that all the gold is out, I stop adding. There are always color changes that occur. I always dissolve the SMB in water before adding. I add in increments and stir after additions. All of the yellow tint will disappear when the gold is out. You can test with stannous chloride in between additions to get an idea of what to look for. Once you get the hang of the color changes, you'll hit it perfectly every time, without adding too much SMB. If you're color blind, you may have problems.