# Incorrectly Inquartered



## Foggy (May 7, 2018)

Hi guys,

I inquartered gold with copper and worked out the following:

7 grams of 18k = 14g of copper. 
32 grams of 9k = 16g of copper.

Yesterday I did three runs of dissolving of my inquartered gold with 50/50 distilled and nitric. I am left with 17 grams of gold which is the correct amount. BUT I've realised now that i only added 15g of copper instead of 30 to begin with... :? Not sure how I stuffed that up. 

But anyway, could I still proceed with Aqua Regia or am i best to resmelt this 17 grams of almost 24 carat gold and inquarter it with 51 grams of silver (will definitely use silver next time around).

Lastly, I know we inquarter to avoid passivation during the AR stage, but I don't really get it - if we add silver or copper to inquart and are just dissolving it away with nitric acid before we reach the AR stage, what's the point of doing it in the first place? 

Thanks guys, - Mike.


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## goldenchild (May 7, 2018)

With your scrap you should have had about 17.5 grams worth of fine gold. That leaves 21.5 grams of base metals. I always make it easy on myself and make the fine gold content of the melt equal 10%. So that would mean you would need a total of 175 grams of base metal. Subtracting the base metal that is already in the scrap that would leave you with about 153.5 grams of base metal that needs to be added to the melt. Adding only 30 grams seems way too low. That would make your fine gold percentage 34%. 9k is only 32.5% fine gold. So you see it would be like just taking 9k and throwing it in nitric.

Anyway, no need to inquart any of the gold that was actually separated from the whole. Just remove any solids from the black powder and inquart that. Then when you have ALL black powder proceed as usual.


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## snoman701 (May 7, 2018)

When you inquart, you are doing so to avoid the creation of silver chloride. 

Silver chloride not only greatly slows or stops the digestion of karat scrap, but will also hold up some gold....so you won't get all of your gold out on the first run...at least without some careful maneuvering. 


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## snoman701 (May 7, 2018)

Do NOT melt silver chloride....huge losses follow.

Mechanically agitate until you have only finely divided silver chloride, then dissolve in thiosulphate and cement on iron. Best done when you have a bunch.


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## g_axelsson (May 7, 2018)

With 90% base metal I would say it's too much base metal. By keeping the gold at 25% the gold doesn't fall apart into a black powder. Inquart means to make a quarter gold.

9 karat is still 50% more gold than 6 karat which is the same as the alloy you make when inquarting.

Inquartion can solve two problems.

1. High silver gold alloys, over a certain percent silver the gold can't be dissolved in aqua regia, the silver reacts and creates a layer of silver chloride. It can't be dissolved in pure nitric either as alloys with more than 6-9 karat or thereabout is sealed by the gold that remains on the surface and the reaction shuts down.
By mixing in more silver it is possible to first remove silver and other base metals before taking the gold to aqua regia.

2. Palladium and platinum can sometimes be hard to get out of gold. Inquarting with silver makes platinum soluble in plain nitric acid. Platinum and palladium follows the silver.

Using silver to inquart with is preferable to copper, not only does it help to remove PGM:s, but dissolving copper takes roughly 2.5 times as much nitric acid as for the same weight of silver. The silver is easily recovered by cementing on copper and can be used over and over again.

If you have inquarted with copper there is nothing that stops you from dissolving the gold in aqua regia, the silver content is so diluted now that it shouldn't create any problem any longer.

Göran


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## Foggy (May 8, 2018)

Thank you all for the replies! Göran, I didn't correctly inquart to begin with so I'm not sure if I can proceed. 
I should simplify, so after all the calculations I started with the following in my jewellery (theoretically):

17.25g gold (44%)
21.75g base metal (56%).

To inquart I was supposed to add an extra 30g of copper to make the total composition:

17.25g gold (25%)
51.75g base metal (75%).

My issue is, I only added 15g :roll: making a total of:

17.25g gold (32%)
36.75g base metal (68%).

So I just want to confirm, am I able to proceed with Aqua Regia as things stand? If not, can someone please advise how I can correct this.

Thank you all, - Mike.


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## nickvc (May 9, 2018)

As you possibly only had 3-4 grams of silver to start in the alloys you are below the level where it will stop the reaction so I’d go straight to AR, you might get a little silver chloride but the gold should all dissolve and the chloride can be filtered off, best done with a cold solution, before precipitating your gold.


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## Foggy (May 9, 2018)

Hi Nickvc,

Thank you for the reply. I think I started with more silver. Correct me if I'm wrong, but isn't 9 carat gold typically comprised of 42.5% silver, 37.5% gold and 20% copper? Which would mean: 

32 grams of 9k = 13.6g of silver.
7 grams of 18k = 1.05g of silver.

Total theoretical starting compositions of non-inquarted jewellery:

17.25g Gold (44%)
14.65g Silver (37%)
7.1g Copper (19%)

Someone please confirm if I'm incorrect? 

Thanks and sorry for the hassle. I just want to be sure, - Mike.


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## nickvc (May 9, 2018)

No typical British 9 carat is 10-12% if it’s yellow if it came from Italy there may well be none as they skip the silver to keep the price down, and 18 carat has very little to none usually.


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## kurtak (May 9, 2018)

g_axelsson said:


> Using silver to inquart with is preferable to copper, not only does it help to remove PGM:s, but dissolving copper takes roughly 2.5 times as much nitric acid as for the same weight of silver. The silver is easily recovered by cementing on copper and can be used over and over again.
> 
> Göran



Goran

Per the underlined - depending on the conditions under which you dissolve copper with nitric it will take more or less (+/-) 4 times more nitric to dissolve the same weight in silver

A gallon (3.78L) of 70% nitric will dissolve only "about" 2 pounds of copper (+/-) where as that same gallon of nitric will dissolve "about" (+/-) 8 pounds silver 

Kurt


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## g_axelsson (May 9, 2018)

Thanks for correcting me, Kurt. Just took that number from my memory as I normally never uses nitric on any large amount of copper. It makes it even better to use silver for inquarting.

Göran


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## g_axelsson (May 9, 2018)

And if you have 17 grams of gold after inquarting and was expecting 17 grams, then there should not be any large amounts of silver left. Just go to AR, any metal that doesn't dissolve could always go into your next inquartation.

The 25% gold 75% silver + base metal is just a convenient limit. More gold and it might not be so easy to dissolve all base metals to the core, especially thick pieces. Less gold and it starts to fall apart into a black powder. There is quite a span that works just fine.

Göran


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## goldenchild (May 9, 2018)

g_axelsson said:


> The 25% gold 75% silver + base metal is just a convenient limit. More gold and it might not be so easy to dissolve all base metals to the core, especially thick pieces. Less gold and it starts to fall apart into a black powder. There is quite a span that works just fine.
> 
> Göran



I just go with 90% base because I can't tell you how many times I thought I had it 75% base and then it ended up being less and therefore couldn't fully digest. I then had to inquart again having no idea how much was actually digested. You then have to add even MORE base metal than originally needed because the gold content is higher. It's a pain in cheeks.

Foggy. The simplest way to dermine the gold content of a karat is to divide the karat by 24. 
9k/24 = .375
10k/24 = .417
14k/24 = .583

and so on.


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## 4metals (May 9, 2018)

Classically inquartation calculations were based on the ratio of silver to gold in a sample after cupellation. cupellation being an assay function where the sample, the added silver, and lead are melted in a furnace and the cupel (usually made of bone ash) absorbs the lead and the base metal leaving only gold and silver. The gold and silver alloy is parted in nitric acid leaving behind gold of approximately 99.5% purity if done right. 

Refiners use the term inquart but often the metals that are nitric soluble are considered when calculating the ratio. If there is a copper it behaves the same as silver and dissolves in nitric acid. But if you are using cupellation and parting to refine it is important that the ratio is 3 silver to 1 part gold after all base metals are removed by cupellation. 

I guess technically we should refer to inquartation as either assay inquartation or refining inquartation. Or maybe I'm just making this too complicated.


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## snoman701 (May 9, 2018)

4metals said:


> Classically inquartation calculations were based on the ratio of silver to gold in a sample after cupellation. cupellation being an assay function where the sample, the added silver, and lead are melted in a furnace and the cupel (usually made of bone ash) absorbs the lead and the base metal leaving only gold and silver. The gold and silver alloy is parted in nitric acid leaving behind gold of approximately 99.5% purity if done right.
> 
> .



The term base metal is often thrown around, but in the case of say 18k gold or even gold filled, where there is a lot copper. (In comparison to the amount of silver)

Does the cupel absorb the copper? Or is it mostly absorbing the lower melting point metals such as lead and tin?




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## g_axelsson (May 9, 2018)

Cupellation is done in an oxidizing atmosphere so there is no metals absorbed by the cupel, it's all metal oxides.

Göran


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## nickvc (May 10, 2018)

Most karat alloys will dissolve very well in AR without inquarting as most large refineries will acknowledge and most will go directly to that route after the assay to save time, I did when I was refining mainly jewellery scrap and needed the metal turned round quickly. The advantage to inquarting is it will carry any PGMs with the silver and it will allow all the gold to be recovered if done carefully the first time, it also makes sense if assays are expensive and you are only working relatively small quantities.


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## cuchugold (May 10, 2018)

4metals said:


> Or maybe I'm just making this too complicated.


 All I ever refine these days (not much) is by inquartation and parting only, followed by your manganese oxide fluxing recipe. What is the latest and newest in this method, including acid recycling, etc ?. :G


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## kurtak (May 10, 2018)

Foggy said:


> Hi Nickvc,
> 
> Correct me if I'm wrong, but isn't 9 carat gold typically comprised of 42.5% silver, 37.5% gold and 20% copper?



Nick replied 



> No typical British 9 carat is 10-12% if it’s yellow if it came from Italy there may well be none as they skip the silver to keep the price down, and 18 carat has very little to none usually.



Mike 

To better explain this - there is no such thing as the "typical" amount of silver in the alloy of "karat" (or carat) gold 

Karat gold alloys can very widely in the composition of the metals used in making the alloy other then the gold

The karat is the reference to the amount of gold in the alloy & has nothing to do with the other metals used in making up the alloy

Example 12K gold is 50% gold - alloyed with 50% "other" metal(s)

Those other metals - used in the alloy - can very widely depending on the characteristic's of the alloy desired by the maker of the gold alloy - characteristic's such as color or hardness etc.

Again - using 12K gold as the example - it could be 12k yellow gold - or 12K rose gold - or 12K red gold - or 12K white gold

The more common metals used in making karat gold are silver, copper, zinc, nickel, & PGMs - however - they also make some exotic alloys using other metal such as iron & aluminum --- silver may - or my NOT be used in the make up of karat gold alloys

Refining karat gold "can" be a problem if &/or when silver is a part of the make up of the alloy - but not all karat gold uses silver in the alloy - whether silver in the alloy presents a real problem in the refining of karat gold depends somewhat on whether or "not" the percentage of the silver will cause a problem - or not

For the most part - the problem with silver in the karat gold alloy becomes a problem when it is a karat gold referred to as "green" gold - green gold is typically 16 - 18K gold (666% - 75% gold) with the rest of the alloy being made up of silver & it is this "green" gold that becomes a problem with refining karat gold & is why/when inquarting is needed with nitric then used to remove the silver

So - other then "green" gold - for the most part - it is not necessary to inquart karat gold to refine it by going directly to AR refining 

In other words - most karat gold alloys can be refined by going directly to AR - including 18K gold - the exception being when the 18K is green gold

In your case - you had 7 grams of 18K & 32 grams of 9K - what I would have done is put the 7 grams of 18k in a beaker of AR --- if the AR was not having a problem dissolving the 18K I would have then simple added the 32 grams of 9K to AR to finish dissolving that as well

If the 18K was having a problem dissolving in AR - I would have then removed the 18K from the AR & then melted it together with the 9K (& depending on a little math) "possibly" add "some" more copper - poured the melt to shot - then gone back to the AR with the shot 

In my opinion - the only way I would inquart & then use nitric to remove silver - is if I was doing a "large" batch of nothing but 16 -18K due to the fact that a fair amount of that 16 - 18K may be "green" gold

Have you read C. M. Hokes book - if not you should

Here is a link to "some" gold alloys (mostly 18K) the only ones that "need" inquarting are the soft green gold & the green gold & "maybe" the deep green gold

https://www.thoughtco.com/composition-of-gold-alloys-608016 

Kurt


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## nickvc (May 11, 2018)

Kurt in many ways you are right about karat alloys but the traditional British 9k alloy is around 12% silver so it will cause problems but a lot of 9 k was made in Italy especially chain and that usually contains no silver, another problem can be 9-14 k white gold alloys which can have the balance as sterling.


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## Foggy (May 12, 2018)

Thank you all for the fantastic replies . I'm going to go straight to AR and see what happens! For the record, my 9k chain was stamped 'Italy' and this is what's left after cementing out. Bit hard to see, but looks like about the same amount of silver as I have gold.

Thanks again everyone, - Mike.


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