Making Auric Chloride at Home: Questions and Comments

Here's where you can comment on my latest tutorial. The tutorial is here:

http://goldrefiningforum.com/phpBB3/viewtopic.php?p=1876

Steve

Great job Steve,

If I understand you correctly, after dissolution you would then move right to Sodium Metabisulfite. Also, is the amount of AU that can be in solution about the same as aqua regia.

-Bill

Nice vid, Steve....

Why stopper the test tubes? I noticed you mentioned that there was pressure building up, and you released it periodically, but this can be very dangerous. Were you concerned about heat retention?

Fever

The amount of auric chloride which can dissolve in an aqueous solution is due to it's solubility of 68 gms/ 100 mL. This varies by temperature , hotter aqueous solutions can dissolve more auric chloride.

Fever,

I'm glad you liked it.

The gas produced was very minimal due to the small scale of the reaction. This was by design for the purpose of filming the video. The toxicity of the gas was the main reason for stoppering. Chlorine is dangerous, but in my opinion not as much so as NOx gases produced by the AR method. As long as you work the reaction as I have demonstrated and provide for good ventilation, this reaction will scale up easily. I feel a crockpot would be a realistic working scale for most hobbyist. Adding more muratic and bleach as required to push the reaction to completion. If silver is in the gold a salt may form.

The amount of heat used was very minimal, just enough to keep the reaction going. If you notice I was holding the vials with my hand ( no tool ), this is how you can be sure there was not that much heat involved.

As sandhog mentioned above you go straight to the bisulfite after filtering if necessary.

Steve

Hi Steve

Great video and good idea.

Question 1:

Could a person use this Aqua Regia to refine both ceramic and fiber CPU chips. Would there be a reaction to the fiber?

Question 2:

Do you have a formula developed as far as the ratio of both Clorox and Muriatic acid?

Question 3:

What would be a good starting point of total AR should be used to refine about 20 ceramic CPU chips at one time with the heat sink removed?

Question 4:

About what temperature would you recommend that the AR be heated: (Naturaly I would do this out doors.) With a crock pot.

Question 5:

Would I also need to neutralize the spent AR before precipitating the gold?

I beleive in the tutoral, you mentioned that the gold would be precipitated as usual with Sodium met.

Steve, I only refine gold plated items only, such as Chips and pins. I use AR on just about every thing except large plated items and then I use my electrolysis cell then. This apears to be some what safer than Nitric acid (sodium nitrate) and muriatic acid, and much less expensive.


Again many thanks for you untiring efforts and contribution to this forum inorder that we all may benefit from your extensive knowledge and experience.

Thanks Again

Catfish

Catfish,

I'm glad I'm getting such a good response to this tutorial, something told me it would be big when the light went off in my head.

I'll try to answer your questions in the order they were asked:

1 ) You are referring to this reaction as AR (aqua regia).. it is not. This reaction should work on any gold which is in a foil or a finely divide state. The ceramic cpus would need to be ground to a very fine consistency to get at the interior gold wires. The solution would need to be filtered afterward. The cpu surface and pins plate would be attacked by the mixture in the video, but the base metals would also be attacked. The foil I used in the video actually was removed from a 486 cpu plate. What are commonly referred to as 'fiber cpus' are mostly epoxy layers with fiber sheets in between. They don't crush very well at all and are, in my opinion, best processed with acid peroxide.

2)The ratios are in fact a combination of two separate reactions the first is known as the HCl-Cl method has been around for quite some time. The method calls for concentrated HCl saturated with chlorine gas. This is the next best mixture to AR for attacking gold. Unfortunately chlorine gas is dangerous to produce and hard to handle for the hobbyist. I was going to show the forum an easy technique for generating the gas and using it in this reaction. That's when I had this brainstorm while formulating the procedure. This procedure is much safer than generating the gas and saturating the HCl with the gas. The original method also required adding chlorine as the reaction progresses which only added complexity.

The second part of the reaction is not as well known as the former but is even older. It's called the Chlorine Water method. This method generates the above required oxidizing chlorine 'in situ' (in the reaction vessel) via the equation:

NaOCl + 2HCl --> Cl2 + H2O + NaCl

and this chlorine gas is then reacting with the additional HCl via

-OCl + -Cl + (2H3O+) --> Cl2 + 3H2O
-OCl + H2O <--> HOCl + -OH

Normally this requires diluting the reaction with excess water to hold the chlorine which is produced by the reaction.

The produced Cl2 in conjunction with additional HCl is the driving force of this newly revealed combination reaction of my own creation.

In essence we have produced Chlorine Water in HCl acid without resorting to the additional chlorine generating equipment. The beauty of this is that the solution is not diluted as in the normal chlorine water reactions (due to the low solubility of Cl2 in water). We use the chlorine ions as they are formed to dissolve the gold.

For the above mentioned reasons I have designed the experiment to run at a pace set by the addition of the NaOCl. By controlling the amount of added bleach we can in effect control the rate of chlorine production 'in situ'. If the heating is closely controlled we can avoid driving the chlorine out of the solution so that it can react with the gold instead. The trick is to add small amounts of the bleach slowly so that only enough chlorine is produced to dissolve the gold. When the solution stops absorbing gold when gently heated just add another small dose of bleach. Remember the chlorine from the bleach will end up in tied to the gold as AuCl initially and eventually as AuCl3. From this we can calculate that it will take 3 moles of NaoCl per mole of Au. As for the HCl it is the initiating molecule and is regenerated as the reaction proceeds. As I mentioned in a previous post the solubilty of Gold Chloride is 68 gm /100 mL in cold aqueous solution, this is a good starting point for your calculation of HCl (31.5% HCl / 68.5% H20). If you have a large amount of foreign material in the reaction you will need more to compensate for the increase volume of the reactants.

3) a. Do the math on estimated amounts of gold to be absorbed based on expected yield.
b. Crush the material to be processed as fine as possible.
c. Setup the reaction vessel in a well ventilated area.
d. Add the calculated amount of muratic from the previous paragraph.
e. Slowly add a very small amount of bleach and observe the reaction rate.
f. Gently heat mixture
g. Slowly add small amounts of bleach until all gold is absorbed.
NOTE: Adding bleach to HOT acid is very dangerous the solution can increase 10 fold or more in volume from the gases generated if added too fast. You will lose your gold if the reaction boils over. It is wise to cool the mixture to room temperature before adding additional bleach. If adding bleach doesn't cause additional absorption, reduce heat, let cool to room temperature, add a small quantity of HCl and reheat.
h. Cool and Filter
i. Precipitate with usual methods.


4) Again, this is not AR. The reaction should be run at the least possible heat (40C or less typically ) to keep it going. Overheating drives off the required chlorine gas and extends the reaction time.

5) Again this is not AR, no need to neutralize, go straight to SMB. Dilution may help precipitation if solution is very concentrated.

WOW !! That was a long post, but I made it through. :lol: Now everyone take a look over it and give me your opinions and suggestions.

Steve

This is a really good tutorial ! I never eared of the technique before... Maybe I'll give it a try soon
Thanks Steve

Why can't I view the tutorial?

Paige

I've noticed some activity on my site that is coming from an unknown location so I'm working on removing the suspected leech. I've temporarily enabled access again. Check it out now and let us know what you think.

Steve

How would you go about disposing of the stripped solution? Does this work on any of the PGM's?

Chuck

The barren solution should be disposed of as with any other stripped solution. Test for valuables, drop the base metals, filter, neutralize, and dispose. I use aluminum foil to drop, I think it was Harold that pointed out that iron or steel also works and is cheaper.

It should work on Pd foil or powder. I doubt it would be effective on the higher PGM's, but I don't know for sure. Anybody know?

Steve

How about usnig a higher concentration of sodium hypochlorate than in bleach. would that speed the reaction as higher concentrations can be purchased at a chemical store or pool store.

P_Carrol,

The higher concentration bleach isn't necessary because the goal is to produce just enough Cl2 gas in the solution to dissolve the foil or powder, the liquid will only hold so much Cl2 and the rest just goes into the air. The low concentration allows the Cl2 produced to stay in the solution and attack the gold instead of going into the air. A second problem with the higher concentration stuff is that the reaction would be more violent when it comes into contact with the acid, making the whole reaction harder to control.

I guess you could go with the higher concentration bleach just use proportionally less of it. The benefit is that the volume of the solution will be less with the higher concentration bleach. Just remember that the solution won't hold all the chlorine gas produced by mixing the acid and bleach and the excess gas will therefore need to be dealt with. Also be extra safe working with the more reactive ingredients.

Steve

What about starting with a full shot of bleach and then drip it in or add an occasional shot?

In practice, the gas dissolved in the solution tends to always decrease and maybe replenishing would help.

Chris,

That may solve the excess chlorine problem, but it also brings up another possibility, start with the bleach in the reaction vessel and add the acid dropwise. I'm not sure if the reaction equilibrium would be greatly affected by the excess hypochlorite as opposed to excess chlorine when starting with the acid. It may be worth testing out. If I recall the equation favors chlorine production with excess acid.

Steve

Steve,

Starting with bleach and adding HCl is very interesting.

I reread your post on the first page. It seems like the best speed is in keeping sufficient Cl2 concentration. If the loss is due to heat generation, the vessel could sit in a little ice. I would think the ideal way would be to drip the bleach in, with stirring, and monitor the temperature. Stirring replaces the spent chemicals, with fresh, at the surface of the gold and makes things go faster. I wonder how an aquarium air pump would work, as a stirrer? It might reduce the Cl2, however. The extra oxygen might help, though. Have you tried HCl, H2O2, and bleach?

Every reaction is a time, temperature, and concentration thing. Speed within Safety is always the goal.

Are you adding any water? Is the ratio of HCl/bleach about 1/1? It might help to prevent foamovers by adding a little anti-foam agent. They sell it where they rent out carpet cleaners. A drop might be enough.

Chris,

The air bubbler is going to introduce more N2 than O2 which may, under these conditions ultimately become a diluted form of AR :!: :?:

Very interesting indeed.

I've yet to try adding any H2O2.

It looks like I have some more experiments to run when I get home tonight.

Steve

Nitrogen is inert. I still think that the 3% H2O2 is holding you back in these experiments. I've used 30-35% H2O2 all my life to jack up dissolving reactions. I've used it with all acids, many alkalis, and cyanide. They all go faster. But, one secret of speed in most reactions is to keep the water out. Three percent H2O2 is 97% water. Even 12% from a beauty supply would help greatly. I have tried 3% on many things without much luck.

I can't find out where to get the tin powder!
what did I miss? lmao

Thanks Steve great job!