HCl/H2O2 followed by HCl/NaOCl

[Traveller11]

Okay, let me start by saying I know nothing of the leaching process outside of what I've read here and on other forums.
That being said, the project I need help with is a beach gold placer deposit. The gold is extremely fine. Although there are thick layers of almost pure black sand (magnetite) on the surface of the beach, I have found the majority of the gold migrates downward a few feet to a layer of clay. However, there is still a substantial amount of iron in this deposit on the clay in the form of black sand and sulfides. There is likely silver and copper present, free and alloyed with the gold and God knows what other base metals.
Just how much of these base metals will the HCl/H2O2 method remove? All of it? If I run out of H2O2 can I use compressed air to keep the HCl aerated?
So, am I correct to assume that, once the base metals are removed, there is nothing left for the HCl/ NaOCl method to dissolve but the gold? Will even the silver, copper, etc. alloyed with the gold be removed by the HCl/H2O2 process?
Rumor has it that there are PGM's in this placer as well. Will the HCl/NaOCl process put any of these into solution?
I realize there are other methods for doing this but most involve nitric acid. As I live in a very remote location, there is difficulty transporting nitric acid as it is classed as Dangerous Cargo. Not to mention the security hurdles one has to jump through just to purchase it.
Bob

 

[Anonymous]

I think you will have problems with the HCL/H2O2 method on placer gold, reason being is that the copper and other base metals are alloyed with the gold the alloyed silver will give problems also.

I think you would have to alloy more silver into the gold then used nitric acid to remove the base metals, then go to the refining of the gold.

Jim

 

[Lino1406]

Silver in your procedure (if working at all) will convert to
silver chloride. Gold if any should make a mixture with it. O2 can act as H2O2 but much slowlier

 

[Traveller11]

Yes, this is what I was wondering, too.
Although it seems clear that base metals apart from the placer gold will go into the AP solution, it is not all that clear if base metals alloyed with the gold will go into the AP solution.
However, if the alloyed metals go into solution with the gold in the Acid/Clorox solution, is there a way to drop these base metals out before attempting to precipitate the gold with SMB?

Bob

 

[butcher]

Traveller11, concentrate, grind fine, good hot oxidizing roast (inceneration), is a must before any leach.

this is recovery stage and there can be several ways to approach it, many types of leaches, and processes. ridding base metals as much as possible. and concentrating value content,
chemical cost and difficulty of process considered if doing this on large scale, saftey must always be considered, also how much waste will you have to dispose of properly.

if silver content high, chloride leaches are less disireable.

smelting, to lead dore, and cupeling and parting button, can help you decide if the material is worth processing and can also give you a good Idea of expected value content and what metals also help in your decision of which leach or process would be best to try

once base metals and gold are in solution together (higher the base metal content the more I recommend), I find cementing with copper better at recovery than using SMB or other chemical to precipitate the gold.

 

[Platdigger]

Here is a leach that uses pool chlorine (Calcium Hypochlorite) and caustic soda (Sodium Hydroxide).

http://www.nuggethunters.org/Leaching.txt