Final refining gold, - brainstorming

[sharkhook]

Just a random thought from someone who once mixed concentrated sulfuric and 3% H2O2. I am glad now there were no metals involved but the glass was very clean. What if a solution of weaker H2SO4, (battery acid) and 3% H2O2 were used, In a large container. Myself, I am very leery of anything, especially acids, that foam up. But the use of the diluted acids H2SO4 such as that used in batteries, and the 3% version of hydrogen peroxide, a formula similar to the AP system could be evolved. I have no idea if I would use it anytime soon, I just see it as possibly another option for those with more experience.

 

[solar_plasma]

The point is AP, which in fact is a misleading term, it should be called something like Steve's(et al.)-CuCl₂-regenerative-copper-etching-system, is reusable. Given the case, that you need CuSO₄ for any other purpose, H₂SO₄ might be a viable option and given the case you have to save time for any reason,the very dilluted "piranha" might be an option to those, who know to make and use it safely.

It is just no AP, it is not similar to AP in any way and people should be aware of that.

Also anyone shouldbe aware of, it makes only sense in the state of recovery. When used for washes, it has great disadvantages, when for example lead, barium or other unsoluble sulphates could be involved. There is in my opinion no alternative to the Harold/Hoke-Washes with HCl, when we talk gold. A special case might be silver powder with only copper as a contaminant, this could be worth a discussion.

 

[freechemist]

Solar_plasma writes: The point is AP, which in fact is a misleading term, it should be called something like Steve's (et al.)-CuCl2-regenerative-copper-etching-system, is reusable.....

This statement is essentially true. The so called AP-method is limited on aqueous HCl-systems. Excessive HCl is an integral part of "AP-solutions". It helps, to held Cu(I)-chloride, CuCl, containing Cu(I), the reduction product of Cu(II)-Chloride, CuCl₂, as anionic chloro-complex, [CuCl₂]^-, in solution, thus keeping it available to reoxidation to Cu(II)-chloride, CuCl₂, through reoxydation by oxygen from the air, introduced through the air-bubbler. Excessive HCl also delivers the hydrogen-ions, H⁺, needed, to form water out the reduced oxygen from the air.

 

[Geo]

AP, acid/peroxide is actually a refining tool. hcl alone will not dissolve gold but it will hold dissolved gold in solution. by adding H2O2 (an oxidizer) to hcl in the presence of gold, the gold will go into solution. it works better on fines and micro-millimeter foils. due to the electromotive series of metals, metals higher in the reactivity series will dissolve first so when using AP to refine gold powder, it should be almost pure to begin with.

 

[solar_plasma]

I wrote:

Also anyone shouldbe aware of, it makes only sense in the state of recovery.

I meant H2SO4 as a tool to remove basmetals, while I dared to state this since it is not only my present point of view, but also already was expressed by others in more or less similar form. And even this might not be always true, - but at least in most circumstances. Ofcourse I agree with you, Geo.