HCL - clorox

[Harold_V]

The crystals in the container should be a pale green/white color. If they are brown, they won't work.

Well you just solved a 30 year old mystery for me.
In my early years of refining, I tried Ferrous sulfate to drop the gold, on the recommendation of an independent assayer I knew.
Didn't work at all.
Couldn't figure out why, and I was surprised because I had been told it was easier than the Sodium Bisulfite I had been using.
The crystals were yellowish and brown.

I'm no chemist, but I believe it's to do with the material having lost an electron. Perhaps Lou could better explain.

The comments I make are generally just knowledge I gained from Hoke. Her book really is a great way to start the process of learning to refine precious metals. Her writing style lends itself well to folks that don't have a chemical background.

I remind readers, I have no personal interest in the book, nor its sales. Just trying to pass along what will prove to be the best information available for the non-chemist.

Harold

 

[eagle2]

Hi Geedub
The Ferrous ion is Greenish, when it starts to look brown in the bottle it has oxidized. Ferrous wil go bad this way if the bottle is not sealed from the air and moisture. Also I think the carbon dioxide in the air plays a part.

Gold gets reduced by Ferrous, because Ferrous takes an electron from Gold in its compounds and Gold becomes a metal. In the process the Ferrous is oxidized to Ferric which is a brown compound.

So Ferric cannot do a thing to reducing Gold anymore. The potential has been used up.

Al

 

[flexyman]

Hi all,
I am so gratefull for this Forum. I have learned so much here. But!
The other day i had disolved some alloy containing gold and Some
other metals. I had added an excess of Clorox and after first making
a small test to ascertain that Sodium meta bisulfite will precipitate gold,
I found no reaction. thinking I had to much Chlorine in my leach Solution
of 2 litres I added 1/4 teaspoon of Sodium thiosulfate to the HCl-Clorox
and stirred the mixture. Low and behold I ended up with the inside of the beacker gold plated and all the gold precipitated out of solution. I filtered
out the gold then put the clarified solution in a clean beaker and hung
some Iron in this solution untill it was PH7 and a surprizing amount of
black precipt lay in the bottom of the beaker. I filtered this out annd have
stored it for further investingtion later. I will apreciate some thoughts
on this.

I love Hyro-metallurgy

 

[Platdigger]

That is some find Flex.
Do you know what other metals were in the alloy?
Randy

 

[Harold_V]

I will apreciate some thoughts
on this.

Assuming all of the gold had been precipitated, and there were no other metals of value in solution, the black material you accumulated will be a combination of carbon (from the steel) and copper that was in solution.

I would suggest you dissolve a little with acid and test for values. If you find nothing, discard. It's not a good idea to save anything that is known to have no value. The day will come when you have so much that it will overwhelm you, and the only way you can sort it out is to test each individual lot.

Harold

 

[jsargent]

Hi all,
I am so gratefull for this Forum. I have learned so much here. But!
The other day i had disolved some alloy containing gold and Some
other metals. I had added an excess of Clorox and after first making
a small test to ascertain that Sodium meta bisulfite will precipitate gold,
I found no reaction. thinking I had to much Chlorine in my leach Solution
of 2 litres I added 1/4 teaspoon of Sodium thiosulfate to the HCl-Clorox
and stirred the mixture. Low and behold I ended up with the inside of the beacker gold plated and all the gold precipitated out of solution. I filtered
out the gold then put the clarified solution in a clean beaker and hung
some Iron in this solution untill it was PH7 and a surprizing amount of
black precipt lay in the bottom of the beaker. I filtered this out annd have
stored it for further investingtion later. I will apreciate some thoughts
on this.

I love Hyro-metallurgy

I'm glad somebody tried this thiosulfate thing. Been wondering about it. Sodium thiosulfate is widely used for de-chlorination, but on the other hand it is also an alternative lixiviant for gold so not sure how it would act with gold already in a chloride form. Maybe Lou could answer this as his chemistry knowledge is superb. Sure would be nice to have a quick and easy way to dispel excess chlorine rather than boiling or letting the solution sit for days.

 

[lazersteve]

As with excess nitric acid, the best solution for excess chlorine is to not produce it in the first place. Learning to control your reaction additions will not only keep your chlorine or nitric levels in check it will save you money on additional chemicals such as thiosulfate or urea.

The addition of more SMB may have very well had the same effect as the addition of thiosulfate.

Steve

 

[jsargent]

As with excess nitric acid, the best solution for excess chlorine is to not produce it in the first place. Learning to control your reaction additions will not only keep your chlorine or nitric levels in check it will save you money on additional chemicals such as thiosulfate or urea.

The addition of more SMB may have very well had the same effect as the addition of thiosulfate.

Steve

No doubt that's true Steve, but if you're doing an HCL+Clorox leach on let's say crushed ore and the clorox is acting not only as a lixiviant but also as an oxidant to maintain adequate ORP levels, (800-900mv) then how can one possibly hold back on the amount one adds? Alternatively if one is doing a leach with HCL + salt + oxidizer (CL, monopersulfate, ozone, hydrogen peroxide, etc.) then the amount of chlorine "added" is totally dependent on the amount of oxidizer used and that depends on the ORP once again. Hence, my dilemma.... I see no way around ending up with a pregnant liquor at the end of the day that has only a minimum of chlorine in it. Then again, if I decide to use ion exchange resin beads to capture the values then it doesn't matter about the chlorine. The more the merrier

 

[Palladium]

Jeff,

You seem to like liquid chemicals.
I see your trying to leach gold ores. Have you thought of this ?

Try a pretreatment of PEROXONE after roasting to finish the oxidation of any un oxidized refractory ores. Then used Cl gas Or Cl gas dissolved in water to leach the gold. Both have different characteristics according to what you are trying to adapt it to. The same also holds true with ozone, but add a little H2O2 to the situation and the rules change yet again with ozone included. If you use ozone you will need about 20 feet of contact time for the ozone and I can't remember about the Cl.

Somewhat like the Platt Kiss method. You could produce the gas with nothing more than the Chloralkali process method. All you need for any of this is electricity ,salt, and water.

I've been doing a lot of research into this avenue and will try my own little experiment one of these days. :wink:

 

[jsargent]

Jeff,

You seem to like liquid chemicals.
I see your trying to leach gold ores. Have you thought of this ?

Try a pretreatment of PEROXONE after roasting to finish the oxidation of any un oxidized refractory ores. Then used Cl gas Or Cl gas dissolved in water to leach the gold. Both have different characteristics according to what you are trying to adapt it to. The same also holds true with ozone, but add a little H2O2 to the situation and the rules change yet again with ozone included. If you use ozone you will need about 20 feet of contact time for the ozone and I can't remember about the Cl.

Somewhat like the Platt Kiss method. You could produce the gas with nothing more than the Chloralkali process method. All you need for any of this is electricity ,salt, and water.

I've been doing a lot of research into this avenue and will try my own little experiment one of these days. :wink:

Thanks for the suggestions Palladium. If money were no object I would give peroxone a shot... but ozone generators are prohibitively expensive for the quantity of ozone I need. Trying to keep things simple. The idea of using only HCL and graphite electrodes to produce chlorine is about the simplest method I've run across. No added chlorine or other oxidizer to buy and I would guess simple control of the ORP via adjustment of the current. If I use resin beads in pulp then I don't even have to mess with precipitation, plus resin in pulp appears to be beneficial for the carbonaceous ore I am blessed/cursed with.