HCl alone

[FrugalRefiner]

Follow-up: is there a consensus on the best way to rejuvenate the HCl--that is, to remove some of the copper II chloride so that it will continue to attack copper (when oxygen is present that is).

powermetalx, lazersteve has a great document on his web site that explains the CuCl₂ (aka AP) process in detail. You'll find a link to his Guided Tour of the Forum in the Tips for Navigating and Posting on the Forum thread. He has links to his site in his signature line. He also has some good videos on his site, including the CuCl₂ process.

Dave

 

[solar_plasma]

Also in the real world HCl does nothing to copper. CuCl2 will etch copper. The HCl and O2 do nothing but oxidizing CuCl to CuCl2.

There is a difference between how thing ARE and how things LOOK like. Yes, in the real world it looks like HCl would etch copper - which it does not -because we do not see the O2 and HCl oxidizing CuCl while the CuCl2 is doing the work.

The difference between theory and practice though is, that in theory we look at small closed quite managable systems, so we can calculate the variables with high accuracy. In practice we often do not know all variables or we are not able to calculate all of them, but the applicated theory will give an approximation that in the best case will be close enough to reach the goal.

There may be very well occur other processes in that leach, in fact they do, but the CuCl/CuCl2-model is exact enough to describe and calculate the output, speed rate, consumption etc "close enough". This will absolutely not be the case, if we use a HCl/Cu-model. This model will not be sufficient to do any predictions, what and when something will happen.

 

[butcher]

In many things we work with with the chemistry of metals, we may have a hard time of describing the reaction, some examples, solubility, saying something is soluble or not, there can be variables that can be hard to describe, saying a salt is insoluble does not mean that none of the salt will dissolve into solution, similar with the reactions of metals and acids,we may also say the metal is not attacked by an acid, because of passivization or for many other reasons, this does not mean the acid has no reaction at all on the metal or the alloy, the reactions of metals and acids may also change with other factors such as concentration of the acid, temperature of the reaction or other details...this is only a couple of examples.

Understanding what is going on, will help us to understand better the reactions, and we may be more able to understand when we say the salt is insoluble, we can understand that even though most of the metal salt precipitated as an insoluble salt, that a small part of that precious metal salt may still be in solution (which we will wish to send to our stock pot for recovery later).