Aqua regia question

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Tylerb752

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Joined
Feb 19, 2020
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12
Im doing a second refine on gold in aqua regia. At most maybe 6 grams of gold. It was all in filter papers so i just threw the papers into a beaker added a little water, hcl, and started to do nitric doses. The papers soon fell apart. I stopped getting much of a reaction so i assumed i had all my gold in solution but couldnt tell 100 percent because of all the paper. I couldnt see any black or brown sediment in the solution though. So i put in a sulfamic acid solution to denox and there was no reaction. So i assume that since there was no excess nitric that i didnt have all the gold dissolved. Ive added probably 13 ml or so of nitric before the sulfamic so i cant believe there is more gold in there

Can i add more nitric now or will the sulfamic acid react with it and cancel it out? Should i filter and add whats in the filter to more AR to see if anything else comes out? Thanks for you help.
 

philddreamer

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Feb 12, 2010
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Location
Lynnwood, WA.
Howdy!
I quickly checked on some of my old notes, and if you expect around 6g of gold, you added about double of the nitric needed,
(Hoke states, 4 fl oz HCI (muratic acid) + 1fl oz HNO3 (nitric acid) will dissolve 1 troy oz of gold. This is equivalent to 3.8ml of HCI + 1ml of HNO3 per gm of gold.) 1 US fluid ounce = 29.5735296 milliliters

Take care!
Phil
 

Tylerb752

Member
Joined
Feb 19, 2020
Messages
12
I agree. Thats why it was so puzzling when the sulfamic acid addition had no reaction
 

nickvc

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Sep 14, 2009
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Location
birmingham
You may have had other metals on the filters so they would have helped consume the nitric or you could have had more gold than you thought.
Test with your stannous that may supply the answer, you could have PGMs present.
 

goldenchild

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Aug 14, 2009
Messages
1,807
Don't keep adding nitric. If you can't see any more sponge you are most likely done. If you want to make sure there is no more sponge left in the paper pulp simply agitate the pulp with a glass rod while hot. Powders would expose itself to AR and give a reaction. If all available nitric is used up then you'll see the powders while stirring.
 

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