Iron in aqua regia

[sayf]

I heared from a friend that iron is one of the aqua regia's enemies , can any one explain to me why could iron cause any troubles if it was dissolved with gold in aqua regia ?

 

[nickvc]

All base metals can and do cause problems if in quantity in your AR solutions.
The best route for all to follow is to do a proper recovery,, ie eliminate base metals as far as possible, and then to refine the recovered gold.
The real art in this hobby/ business is the recovery processes not the refining in most cases.

 

[ólom]

All base metals can and do cause problems if in quantity in your AR solutions.
The best route for all to follow is to do a proper recovery,, ie eliminate base metals as far as possible, and then to refine the recovered gold.
The real art in this hobby/ business is the recovery processes not the refining in most cases.

What problems can it cause if there is a lot of base metal? For example, iron.

 

[Yggdrasil]

What problems can it cause if there is a lot of base metal? For example, iron.

Well first of all we want the Gold to be as pure as possible.
And one of the best ways to achieve that is to make sure the Gold is as pure as practical before actual refining.
Another issue is that Nitric is expensive and may create trouble later in the process.
By removing the base metal either mechanically, with AP or HCl.
One saves Nitric, processing time and avoids issues later in the process.
And maybe more as well.

 

[ólom]

Well first of all we want the Gold to be as pure as possible.
And one of the best ways to achieve that is to make sure the Gold is as pure as practical before actual refining.
Another issue is that Nitric is expensive and may create trouble later in the process.
By removing the base metal either mechanically, with AP or HCl.
One saves Nitric, processing time and avoids issues later in the process.
And maybe more as well.

Thanks for the answer!

 

[kurtak]

Garbage in garbage out - in other words the more garbage you have in solution the more likely it is that garbage is going to contaminate the precious metals when you go to drop the precious metals from the solution

I heared from a friend that iron is one of the aqua regia's enemies

Although iron is "somewhat" of a problem (as well as other base metals) I wouldn't really call it an enemy as it can be delt with "relatively" easy

The real enemy is tin - other wise referred to as the refiners nightmare

Kurt

 

[ólom]

Garbage in garbage out - in other words the more garbage you have in solution the more likely it is that garbage is going to contaminate the precious metals when you go to drop the precious metals from the solution

Although iron is "somewhat" of a problem (as well as other base metals) I wouldn't really call it an enemy as it can be delt with "relatively" easy

The real enemy is tin - other wise referred to as the refiners nightmare

Kurt

Thanks!

 

[FrugalRefiner]

Another consideration I haven't seen mentioned yet is that of multivalent metals. Some metals, like silver, exist in primarily one oxidation state, or valence when dissolved. For silver that is usually Ag^-. Other metals, like copper, can exist in several different oxidation states, or valences, like Cu^- and Cu^2-, which works to our advantage in the CuCl₂ (aka AP) leach.

When metals like this are in solution with gold, they can change their oxidation states, causing problems with precipitation and re-dissolution of the gold. Iron is a real chameleon, existing in numerous possible oxidation states, and these can react in the same way as copper, causing problems when trying to drop the gold, as well as the drag down of iron in the precipitated gold, requiring further refining to obtain pure metal.

Dave

 

[ólom]

Another consideration I haven't seen mentioned yet is that of multivalent metals. Some metals, like silver, exist in primarily one oxidation state, or valence when dissolved. For silver that is usually Ag^-. Other metals, like copper, can exist in several different oxidation states, or valences, like Cu^- and Cu^2-, which works to our advantage in the CuCl₂ (aka AP) leach.

When metals like this are in solution with gold, they can change their oxidation states, causing problems with precipitation and re-dissolution of the gold. Iron is a real chameleon, existing in numerous possible oxidation states, and these can react in the same way as copper, causing problems when trying to drop the gold, as well as the drag down of iron in the precipitated gold, requiring further refining to obtain pure metal.

Dave

Thanks!