Help building a Aqua Regia System

[4metals]

The beauty of what @anarxi says is you will learn how simple the inquartation route is, and it is also very scale able.

That would require large furnace (i have 1kg furnace now)

A 1 kg furnace is rated for 1 kg of pure gold so the quantities suggested will not fit in the furnace even though it is one kilogram. Inquarting larger lots in an inexpensive gas furnace is an option and parting the alloy in 1 kg quantities will be a good way to start.

 

[Anil]

Your losses were probably because of Silver Chloride in aqua regia. Especially if you approach 10% Silver.

I think your best bet will be inquartation and double parting with nitric acid. That can get your purity in excess of .995 without dissolving the gold in aqua regia. And you will recover all of the Silver you need to add for the process plus all of the Silver in the alloy.

The benefit of nitric parting is it can be done in stainless steel so no glass breakage worries. We have had members here measuring gold refined this way by XRF and getting results of .999+ (specifically a refiner in Vietnam).

The volumes you are working with can be easily transferred by vacuum and the final rinses with Distilled Water can be easily lifted and poured.

Inquartation will require silver twice the amount of gold content to make it susceptible to reaction with Nitric acid. This will be more expensive apart from stocking Silver if inquartation is required every time. 10% Silver for aquaregia should not be much of a problem if you have a very good stirring system and provide some additional time for reaction in the dissolution stage. With aquaregia one easily achieves 999 purity whereas inquartation after multiple wash will end up gold with 998 purity if acceptable for the market which normally trades in 995 or 999 purity gold as standard.

 

[Yggdrasil]

Inquartation will require silver twice the amount of gold content to make it susceptible to reaction with Nitric acid. This will be more expensive apart from stocking Silver if inquartation is required every time. 10% Silver for aquaregia should not be much of a problem if you have a very good stirring system and provide some additional time for reaction in the dissolution stage. With aquaregia one easily achieves 999 purity whereas inquartation after multiple wash will end up gold with 998 purity if acceptable for the market which normally trades in 995 or 999 purity gold as standard.

The Silver are not consumed so that may be considered a temporary investment
It will be reclaimed and reused.

Edit for spelling.

 

[Anil]

just split it into parts.
250 grams of gold (no matter how many karats) and 750 grams of silver.
make a batch.
return the silver, and repeat the process.
a little more fuss, but with a homemade setup it will be even more.
Besides, by processing small batches, you will lose less if an accident occurs.

The more the number of processes, the contrary, you will end up with more loss than a single process. The multiple processes to finish the same qty of gold will require more time if you adopt to batch process. Of course, it all depends on the capacity of the equipment you have for each stage of refining.

 

[Anil]

Tge Silver are not consumed so that may be considered a temporary investment
It will be reclaimed and reused.

I am hinting at a lengthy processing time you need to recover silver from silver chloride and put it back for inquartation.

 

[Yggdrasil]

I am hinting at a lengthy processing time you need to recover silver from silver chloride and put it back for inquartation.

There are many ways to do that including cementing.
And I commented because the
way you worded it it seemed to me that the Silver was lost.
The amount of Silver is dependent on the karat of course, but also depends on the alloying elements in the Gold.
But there are ways to do it directly without quartering but that may be too costly with respect to equipment.
Inquarting is a well proven and effective method.

 

[Anil]

No, Sir, I did not mean Silver is lost. I said one has to create an inventory of Silver to process gold by inquartation process instead of Aquaregia. One may have a 2Kg capacity refinery set but has 5-10 Kg of gold for refining with 10% silver in it. You may inquart first two kg with Silver and recover silver to make the next 2 kg batches and so on...thus requiring higher silver inventory. But in any case, Silver is an investment that remains and grows over time in value if losses are not there during the recycling and recovery of inqurted Silver. Thank you Sir for your observation.