Gold refining method selection question

[AlkalineHume]

Hi folks, I've been reading and digesting a lot of info from the forum and trying to understand how the different methods for gold refining work at scale as well. Looking at the most common methods (Miller chlorination, inquartation/parting, aqua regia, and Wohlwill) I was trying to sketch out when/why refiners would use one method over another, presuming they have access to equipment for all of them. This is the best I could come up with. Granted there are plenty of variations within each category, but I was hoping to get the broad strokes right. I wanted to bounce it off this forum to see if I've understood the main considerations in selecting one route over another or if I'm missing a key consideration or completely off. In other words, please roast my slide!

My assumptions are mostly as follows:
1. Miller is preferred for cost reasons provided the inputs and purity required are compatible.
2. Wohlwill is least preferred unless >99.99% is required and the input must be pre-refined to >98%
3. Between IQ-P and AR, IQ-P would be preferred where possible

Please roast those assumptions as well. Thanks in advance for any feedback!

 

[Yggdrasil]

Hi folks, I've been reading and digesting a lot of info from the forum and trying to understand how the different methods for gold refining work at scale as well. Looking at the most common methods (Miller chlorination, inquartation/parting, aqua regia, and Wohlwill) I was trying to sketch out when/why refiners would use one method over another, presuming they have access to equipment for all of them. This is the best I could come up with. Granted there are plenty of variations within each category, but I was hoping to get the broad strokes right. I wanted to bounce it off this forum to see if I've understood the main considerations in selecting one route over another or if I'm missing a key consideration or completely off. In other words, please roast my slide!

My assumptions are mostly as follows:
1. Miller is preferred for cost reasons provided the inputs and purity required are compatible.
2. Wohlwill is least preferred unless >99.99% is required and the input must be pre-refined to >98%
3. Between IQ-P and AR, IQ-P would be preferred where possible

Please roast those assumptions as well. Thanks in advance for any feedback!

Welcome.
Additionally the raw material dictates much when a prosess is selected.
The Miller Chlorination was selected for dore and similar all metallic raw material, as the Chlorine bubbled through the material will convert all but precious metals to slag.

I don't know how much it's used anymore.
For dore with much Silver inquarting must be done and so on.

What kind of material do you have access to?

 

[4metals]

It all depends on the speed of turn around which needs to be weighed against waste generated and cost of reagents. And, of course, scale comes into the picture as well.

Small to midsize operators needing high purity will benefit from the inquarting and parting with the parted gold either refined in aqua regia for fast turn around but there is aqua regia waste to deal with. The parted gold can also go through a Wohlwill cell but that process hangs up considerable values for some time and full system accountability can only be measured when the system is broken down and cleaned up. So losses from theft can be difficult to catch quickly.

The Miller Process involves molten gold and chlorine gas. Chlorine gas brings with it many challenges in handling. It is however, fast and efficient but you will need to process your Silver Chloride routinely to catch the gold entrained in the chlorides. Not difficult, but also cannot be overlooked. The product from the miller process can go into either a Wohlwill cell with the draw backs mentioned above, or use a technology called surface effect gassing which requires high purity going in (as does Wohlwill) but produces .9999 gold quickly and efficiently. A video of the surface effect gassing process can be seen HERE

 

[cejohnsonsr1]

Hi folks, I've been reading and digesting a lot of info from the forum and trying to understand how the different methods for gold refining work at scale as well. Looking at the most common methods (Miller chlorination, inquartation/parting, aqua regia, and Wohlwill) I was trying to sketch out when/why refiners would use one method over another, presuming they have access to equipment for all of them. This is the best I could come up with. Granted there are plenty of variations within each category, but I was hoping to get the broad strokes right. I wanted to bounce it off this forum to see if I've understood the main considerations in selecting one route over another or if I'm missing a key consideration or completely off. In other words, please roast my slide!

My assumptions are mostly as follows:
1. Miller is preferred for cost reasons provided the inputs and purity required are compatible.
2. Wohlwill is least preferred unless >99.99% is required and the input must be pre-refined to >98%
3. Between IQ-P and AR, IQ-P would be preferred where possible

Please roast those assumptions as well. Thanks in advance for any feedback!

Regarding assumption #3. It’s not a matter of choosing one of the other. Inquartation and parting is the first step in refining karat scrap gold. The parting is done with nitric acid distilled water. Once all of the silver and base metals are removed, you still have to remove any remaining impurities with AR, which is nitric acid and hydrochloric acid. If done properly, the resulting gold (in elemental form) can be melted into an ingot of 999 fine gold (in metallic form).

 

[haveagojoe]

Hi folks, I've been reading and digesting a lot of info from the forum and trying to understand how the different methods for gold refining work at scale as well. Looking at the most common methods (Miller chlorination, inquartation/parting, aqua regia, and Wohlwill) I was trying to sketch out when/why refiners would use one method over another, presuming they have access to equipment for all of them. This is the best I could come up with. Granted there are plenty of variations within each category, but I was hoping to get the broad strokes right. I wanted to bounce it off this forum to see if I've understood the main considerations in selecting one route over another or if I'm missing a key consideration or completely off. In other words, please roast my slide!

My assumptions are mostly as follows:
1. Miller is preferred for cost reasons provided the inputs and purity required are compatible.
2. Wohlwill is least preferred unless >99.99% is required and the input must be pre-refined to >98%
3. Between IQ-P and AR, IQ-P would be preferred where possible

Please roast those assumptions as well. Thanks in advance for any feedback!

I would say that simplifying the choice like this is not really possible. The methods do not fall so neatly into categories, since what would appear to be variations may often actually be chemically entirely different. There are a number of other popular methods, and the appropriate method is chosen according not only to the characteristics of the source material, but also the availability and cost of the chemicals and equipment required, safety and environmental factors, legislation, scale, speed, and numerous other factors.

Also the popularity of a particular method should not necessarily be taken as an indicator of its validity or appropriateness- for example, most gold newly extracted from ore globally is leached with cyanide and is often recovered with mercury- among the most environmentally damaging methods available. The expense of environmental management and cleanup should be factored into the economy of the process, and thereby in determining its validity, and should be taken into account in the method selection, but it often is not.

All this being said, my points assume the term "refining" to be taken in the broadest sense, to include recovery, but you may be interested specifically in the stricter sense of refining impure gold to high purity.