A Tale of Two Clorox – A Question.

[Astraveller]

I hope this post is not too rambling but I would welcome any thoughts that you guys have on the following.

The Idea.

I had the thought that it may be a good idea to take the gold from gold plated components direct with the ‘Clorox’ acid/bleach process. The idea was to immerse several components in acid bleach and then remove them when the gold had been dissolved but before the base metals had been attacked too much. Then to drop the gold from the Auric chloride and clean the black powder with 32% HCL/water/ammonium to remove any impurities.

First question(s):- Has anyone tried this? Can anyone point to threads where people have tried this? Does anyone have any thoughts as to whether this might work as a gold retrieval method? I have studied the site and can’t find any reference to this.

I have been using 32% HCL and cheap domestic bleach (which I assume is 2-5% Sodium Hypochlorite) to dissolve gold finger foils with great success.

It occurred to me that if 2-5% hypochlorite worked well then 15% hypochlorite might work better. I have a five gallon drum of Sodium Hypochlorite which I got from my local farmers coop.

What I did.

I put roughly two cups of HCL into two Pyrex dishes and a small amount of ‘strong’ bleach in one and a small amount of ‘domestic’ bleach (Clorox equivalent) in the other. Both fizzed but the strong bleach immediately produced a white (salt like) powder that lay in the bottom.

2nd question:- what’s that?

Then I started to add various components to the mixes. The components were; bits of ceramic cpus with gold pins, fiber cpus with gold pins, bits of gold plated boards, cpus with gold lids, and those chips that I call ‘gold flash chips’ the ones with the ceramic lids and the spiders web of gold underneath (these had been ‘spliced’ to remove the ‘solder’ side of the board), and finally the little bit of gold pcb you find inside a Rockwell chip.

A bit of a mixture I know but they were all just gold plated bits and I just wanted to see what would happen.

The liquid in the two dishes started to turn yellow, as would be expected, as the gold is dissolved. The strong bleach started to turn green first, which is the process attacking the copper first, I assume. So I started to remove the components as they appeared to be ‘done’. By ‘done’ I mean they had lost their ‘goldness’. I put the discarded components into a separate dish. (Slops).

As I continued to ‘play’ the strong bleach got greener quicker than the weak bleach. After a while (an hour or so) I took a look at the slops and noticed that there was still gold on some of the components, most notably the gold lids. The gold was still there but discolored, so I put them back into the solutions. For the most part I put them back into the weak solution because I wanted yellow Auric Chloride rather than green because I don’t know (yet) how to get rid of the copper after dropping it.

Next day.

The green (strong) solution was now yellow (still with it’s salty sediment –otherwise clear) and the originally yellow (weak) solution was now dark green with foils of gold in it and bits of undissolved gold, pins and debris and looked like the result of an AP or straight HCL process.

But here’s the thing.

The slops dish seems to have more gold (visible foils) in it than the other two. Obviously the strong acid bleach dish has gold in solution, so no gold foils. The weak acid bleach dish has, at some point stopped dissolving the gold and has reverted back to only dissolving the base metals but is there some gold still dissolved? (Stannous, I know!) and how to get it back cleanly?

But the slops seem to have produced foils from apparently ‘spent’ components.

Question 3 :- Is it possible that a weak acid or acid/bleach or acid/peroxide ‘crockpot’ could be used to loosen gold plated material without creating too much base metal contamination?

This is counter intuitive, I know, but goes back to a discovery I made when I started to get into all this – that is, that weaker HCL works better than concentrated HCL in the AP process. http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=4249

This raises so many other questions in my mind (and possibilities) but for now let me just post this and ask the other questions as ‘thought and reports’ come in.

Linton.

In the photo, strong is on the left, weak on the right and slops below – you can’t see the gold foils but they are there.

 

[jimdoc]

This has been discussed before,you should be able to find it.
Basically you want to get rid of the base metals in the first process-AP
Because it will give you cleaner gold in the clorox final stage.
Trying to shorten the process will only get you gold of a lesser purity,
and cause you more steps to clean it up.
If I find a link to the previous posts I will add them here.
Jim

 

[Astraveller]

Thankyou Jim,

I thank you and welcome any help that’s out there. I have taken Fingers to Buttons using the AP and ‘Chlorox’ process several times. (Game on! I’m a gold refiner!!) I am now trying to figure out what to do the rest of the bits. These are my second and third buttons.
They are huge and heavy. 

 

[lazersteve]

The observations you made about the more diluted acid are exactly what I would expect. The dilution gives the solution more water to absorb the copper II chloride you are forming (dark solution).

As for why it behaves like acid peroxide (AP) is because, quite literally, it is essentially AP with chlorine as the oxidizer as opposed to peroxide. Lou has pointed out on several occasions that AP is truly a misnomer as the active ingredient is actually copper II chloride. Read the copper II chloride document on my website to understand the chemistry behind this wonderful copper etchant.

The salt in the concentrated batch is either regular sodium chloride (table salt), chlorine hydrate, or a mixture of the two.

Some of the first posts I've ever posted to the forum deal with the nature of the various solvents for gold and copper.

Here's a link to a chart I posted a few years back that may clear things up a little if you understand chemistry.

Gold Etchants

In plain English the chart demonstrates that all of the favorite methods discussed here on the forum will dissolve gold, only at different rates. What this also means is that they will dissolve copper and other base metals.

Since the parts were plated with gold on the outside, the gold initially began to go into solution, but as soon as the etchant penetrated the outer layer of gold, the copper becomes the new target of it's etching power since copper is more reactive than gold.

As the area of exposed copper (or base metal) grows, the ratio of gold etched to copper etched decreases. This means that there exists a point for a given concentration of etchant, that the gold will no longer be the metal being attacked. Unfortunately this point is reached very quickly and the initially dissolved gold is them cemented back out onto the exposed copper. This explains why you are seeing gold in your 'slop'. The truth of the matter is that within a very short time after you added the components the gold was no longer being dissolved. Any gold that was luckily enough to get dissolved is quickly cemented back out onto the copper surface.

I have done some similar work with AP and DiButyl Carbitol (DBC aka BDG) attempting to extract the dissolved gold in the upper DBC layer as it is stripped from the surface of the plated scrap. I met with limited success as the peroxide in the solution works to precipitate brown gold powder back into the mix. I think with some work this may be a viable method in a modified form.

In a nut shell you'll never recover all of the gold off of the plated scrap without using either the sulfuric stripping or dissolving the base metals.

Steve

 

[Astraveller]

Steve,
Thank you for your reply. If you caught my early edits - you have my measure :lol:
Linton.