PM load in aqua regia

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pugle1

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Oct 11, 2012
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I've run several searches, and can't seem to find an answer to this. I was curious about PM ( gold, silver) load in a given amount of aqua regia. Assuming that the aqua regia solution is the recommended 3:1 mix, how much gold or silver can a set quatity of AR hold? ... ie say you have 1 liter of AR solution being made up of reagent grade acids, what quantity of 999 fine gold and silver is it that can be held in solution before no more PM's will be disolved? I guess what I'm asking is this ...What is the saturation point for that said liter of AR?
 
6 or 7 oz of gold will dissolve in 1 liter of AR. Except for trace amounts, silver doesn't dissolve in AR. It combines with the Cl from the HCl to form silver chloride, AgCl, which is a solid.
 
Thanks for the reply... the part of the question about silver was a "D'oh!" moment... knew that already. I plan to do inquartation with silver to end up with silver nitrate then refine the gold with AR. So is there a formula somewhere where I can do my own calculations as to how much AR is required in order to disolve a set amount of gold? I guess I need to see the calculations section for that.

I'm just new to all this and I've been reading, reading, reading.... The Hoke document included. So much to learn and so much more to learn. Then I think I'm going to try to learn some more.... :p . Maybe I'll manage to learn something along the way too.... one never knows, does one?

Thanks again :)
 
Before beginning your work spend plenty of time studying, the time will be well spent for when you are ready to begin.
Hokes book is a great resource for that study.
In Hokes she gives the information your asking about, she say's 1 fluid ounce of HNO3 and 4 fluid ounces of HCL will dissolve one troy ounce of gold.

From this we can make ourselves a chart or graph, using conversion charts to convert from one liquid measurement to another (ounces to milliliters and so on), and using troy weight charts to convert one weight to another (troy ounces to grams or pennyweights Etc.) , with just a little math we can figure and make this chart of how may fluid ounces or milliliters will dissolve how much gold in grams or whatever we choose we can also show how many teaspoons of acid it takes to dissolve a gram of gold, I have made myself a chart like this and you will be surprised after making yours how little acid is really needed.

Another chart can be made from the posts GSP has made where He has given on how much nitric will dissolve copper or base metals, or silver, from these you can figure how much nitric to use when removing these metals from in-quartered karat gold.

This chart will give you a good base line to follow, when making aqua regia to dissolve gold it is better to add the amount of HCl needed from your equations and only add nitric is small portions, (portions of the calculated amount) so you will use less nitric than the equation, but will not have free nitric to remove later, your chart can help you to know the maximum amount of nitric you will probably need to add so that you do not mistakenly over do it.
Sorry I do not have my notes with me now or I would give some examples.
 
I appreciate the feed-back butcher, very much. Some of the questions that I was going to ask I've already been able to answer my self, by reading the Hoke document. I'm already on my way through it for the second time. Too, many of the answers to questions I've had, I've been able to get from right here in the forums via the search feature, or just by going through the different threads and reading input from experienced refiners / experienced hobbyists.

I'm glad I was able to find this forum, and even more so that I joined. Again, as I said before. I have much studying to do, and much to learn. I'm nowhere near ready to start down the reining road yet, but I've already taken in a lot of info regarding safety, fumes, methods (and madness). I want to do things correctly. Proper set-up of a good fume hood / scrubber. I'm not knocking Mason jars, but I'd like to get some good lab glass, stirring table, proper storage vented flasks etc....

So in the mean time, I'll do as much studying as I can.

You folks are great. Thanks
 
I am also very glad you are not knocking my mason jars and thrift store kitchen lab equipment, as my humble little lab serves me well.
:lol:

Based on Hoke's 4 fl oz HCl : 1 fl oz HNO3
Values are approximate as condition such as heating and evaporation or purity can vary figures a little.

1 gram of gold will dissolve in 3.8 ml HCl : 0.95 ml HNO3

10 grams of gold will dissolve in 38 ml HCl : 9.5 ml HNO3

About 8 table spoons of HCl : 2 table spoons of HNO3 will dissolve one troy ounce of gold.

About 120ml HCl and 30ml HNO3 will dissolve one troy ounce of gold.

4ml HCl and 1ml HNO3 will dissolve 1 gram of gold.

1 troy ounce = 31.103 grams

Approx. 2.8ml diluted HNO3 (70%HNO3 mixed with water 50:50 mix) will dissolve one gram of silver.
Approx. 8.3ml of this same diluted HNO3 solution would dissolve one gram of copper.

Most people when they begin use way too much acid.
 
to this problematic

i made some calculations about how much acids i need to dissolve gold powder during purification

you have to count with decomposition of HNO3 and reverse reaction with water molecules also in a case of HCl gas

for gold powder i use 0,4 ml of HNO3 and 2 ml of HCl for a gram of gold ( with 1:1 AR: H20 ratio )

reaction starts itself, after half hour it need to be heated to cca 80 degrees for about hour to complete reaction

some kind of condenser is needed

sometimes, if you heat it too much you need to add few drops of acids

in this case i am able to push an ouce of gold into cca 150 ml ( that makes cca 1 Mol.dm3 Au3+ sol )
 
This is great! 8) . Butcher, Sucho, you're a great help. This is the kind of info I'm looking for. That, plus the info gleaned from Hoke. I'm making hard copy (printing) anything relevant to what I need to know including the Hoke document. I plan on having it close by as reference for my first refining / melt. I'm so impressed with the knowledge base in this forum and I'm having such a great time going through all the threads and reading of mistakes, and successes ... seeing what works and what doesn't ect ... I have no doubt that by the time I'm ready to go, that I'll have no fears or trepidation .... just a good knowledge base on which to rely.

I'm really enjoying posts from the more experienced and I'm learning so much.

BTW ... my real name is Paul, and I'm so glad to have come into such and excellent group. I'm looking forward to sharing my experiences and the outcomes and applications of what I've learned here. Thanks again folks for the great feed-back.

Looking forward to many more posts once I get things going.

Cheers! 8)
 
Unfortunately, the numbers Sucho gave are about 1/2 too low, if you're dissolving in open containers, which is what most people are doing.
 
GSP, the water added to HCl and HNO3 mixture makes the work.

i always use erlenmayer flask and funnel as a condenser :roll: it works perfectly with almost no efford
 

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Water and refluxing kept the gases in solution to do more work, that would vapor off as fumes in a more concentrated solution and open vessel.

GSP was stating that it takes more in open vessels without added water and refluxing, where gases carry off un-reacted fumes of acids.

Very nice saturated solution Sucho that is some very pretty liquid.
 
That's another thing too ... I knew that the vapors (NOx and such ) could be recycled back into the system or suppressed as it were. Once I'm actually ready to give it a go, I'll come back and review several peoples set-ups. I'm looking to do this while producing the least amount of noxious fumes as possible while being as efficient as possible. Awesome pic sucho :)
 
rarefindsprospecting said:
Should i be heating my ar solution while dissolving gold?
Click to expand...

Are you dissolving gold or ore? You need to give the right information to get the right information.
Things are very different dealing with ores.

Jim
 
With contents of only gold silver and copper, i can filter out the silver chloride i believe is correct precipitate the gold with an equal amount of smb as estimated amount of gold right? Not overlyy concerned with the copper at this stage as it is in low low % and i have not yet aquired the proper substances to remove it
 
You can always answer this question yourself--weigh up your refined 99.9% Au, dissolve it in aqua regia and evaporate until it slushes. Then you know the solubility limits.

In any event, you can have 500+ g/L Pt or Pd in solution. Gold is also very well soluble in aqua regia, perhaps 10-12 ozt/liter.
 
thrift stores rule, i will be separating my gold and silver from a batch of ceramic cpu today, if your processing ceramics don't forget the ice in your beaker (pickle jar) after using your AR, no ice you get a mess.
 

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