Trying to condense AR but had a question

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jmfranc

Member
Joined
Oct 14, 2013
Messages
18
I did do a search but didn't find anything but AR condensing for jewelry, so my question is this:

Do I need to add nitric as it condenses so that the gold does not come out of solution? Or did something else cause it to come out? And this is what happened:

Couple days ago I wanted to condense a batch of AR which didn't contain that much gold - or so I thought. I decided to let it sit on medium heat until it condensed by half. Took about 8 hours. When I was done I found a billion little gold sparkles like someone dumped ultra-fine gold glitter in the condensed AR which I think at this point was just muratic acid. The gold particles were ultra-clean shiny gold. I've never produced such clean gold from any AR drop. Maybe I should forget SMB and just remove all nitric? It's really, really clean looking gold.

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Can I ask please:

1. Why are you condensing? What's the reason?
2. If you are condensing why not filter it first since you have raw product inside the jar?

Jon
 
So my question remains, do I need to add nitric as the AR solution is condensed? I do not have a set up for capturing what is steaming off of the AR solution.

To answer your reply post: silicone chips were added after everything was filtered and condensed because I wanted to see if the exposed gold bonding wire would have any reaction so that I could test to see if any nitric was present. It was what I had available with exposed gold. And there was no reaction which leads me to believe that all of the nitric steamed off with the distilled water. I condensed the AR because what I ran ended up having a lot of distilled water added to it. It was a batch of ash/dies/bonding wire from about 40 DDR chips. Because of all of the rinses it required to prepare it it for AR it ended up carrying over distilled water with it. What you see in the jar is after it was filtered, ash removed, and that multiple filter/rinse process added additional distilled water. I wanted to get every drop of the HR solution out of what I ran. And I read here on the forum about people reducing the volume of their AR to help with a cleaner drop.
 
OK

Well firstly - reducing the volume of your AR doesn't give a cleaner drop. Secondly thanks for answering the question about the components. Thirdly my first point answers your question because reducing your volume doesn't achieve what you though it would.

I'm sure someone will be along to complicate the matter soon enough but there's the short answer to your question. Hope it helps 8) 8) 8)

Jon
 
So I am still curious what happens when you evaporate AR. What evaporates first? Water? Nitric? Does it all evaporate as an equal solution? Meaning that you are in essence evaporating gold?
 
jmfranc said:
So I am still curious what happens when you evaporate AR. What evaporates first? Water? Nitric? Does it all evaporate as an equal solution? Meaning that you are in essence evaporating gold?

Initially you're actually taking out a combination of Nitric and water and HCl. Hoke advocated evaporation as a method of denoxxing. If you have excess Nitric then you'll see brown fumes, then these fumes will change to white fumes. At this point theoretically the components left are water and HCl, and that's the source of the white fumes.

Your gold is present as gold chloride and no you don't evaporate that off. You've had a situation here where you've precipitated gold. I've seen it before myself too but I'm sadly not a good enough chemist to detail the process that leads to this with surety, but I hope that the rest of the information helps.
 
Purely evaporation doesn't precipitate gold by itself. I've forgotten some gold chloride on a hotplate once or twice and never had it precipitate even after drying it up totally.

If you want to redissolve the gold you have to add some more oxidant. I would suggest using bleach or hydrogen peroxide with HCl to dissolve the gold again, the precipitated gold is so fine it will dissolve easily and bleach or hydrogen peroxide is easily removed so it doesn't interfere with precipitating the gold after filtration.

I agree with Jon, dropping gold from a weak or strong solution doesn't have to affect the purity. Dropping gold from a strong solution often gives a more dense gold and easier handled. A weak solution often gives a very fine precipitate.

By evaporating you will keep down the volume of waste you need to get rid of (or putting in the stock pot) and that is always a good thing.

Personally I think I would just drop the gold, let the beaker stand for a day and then carefully decant or siphon any barren liquid until I disturb the gold layer. Then with just a bit of HCl and some bleach I would dissolve the gold, filter and precipitate again. This will bring down the amount of liquid in the final drop as well as removing a lot of the base metals.

Göran
 
g_axelsson said:
Personally I think I would just drop the gold, let the beaker stand for a day and then carefully decant or siphon any barren liquid until I disturb the gold layer. Then with just a bit of HCl and some bleach I would dissolve the gold, filter and precipitate again. This will bring down the amount of liquid in the final drop as well as removing a lot of the base metals.

Göran

Sounds like a solid plan right there. When allowing a solution to settle after adding the precipitant, you can use an led flashlight or laser pointer. Hold it to the side of the glass container, and allow it to settle until it looks absolutely clear. If it appears hazy let it sit a bit longer. Don't forget to test your solution as progress through the steps.
 
This may be of interest... Silica, in the forms of quartz (Baghalha, 2007;Mohammadnejad et al., 2014a), pyrophyllite (Mohammadnejad et al., 2014b), feldspar, kaolinite, and mechanically activated silica, has been found to reduce gold complexes from chloride solutions. Mechanical activation of silica can break the covalent SiO bonds and create reactive sites (free radicals of ions) where the gold chloride complex can first adsorb and then precipitate
I suppose the doped silicon acted similar
 
Lino1406 said:
This may be of interest... Silica, in the forms of quartz (Baghalha, 2007;Mohammadnejad et al., 2014a), pyrophyllite (Mohammadnejad et al., 2014b), feldspar, kaolinite, and mechanically activated silica, has been found to reduce gold complexes from chloride solutions. Mechanical activation of silica can break the covalent SiO bonds and create reactive sites (free radicals of ions) where the gold chloride complex can first adsorb and then precipitate
I suppose the doped silicon acted similar

Well then I am going to try that one. Really would see that fine shiny goldpowder in realtime 8)
 
In this post people use the word 'condense', when they actually mean evaporate, why is that? Is it a language thing? I'm not English myself.
 
archeonist said:
In this post people use the word 'condense', when they actually mean evaporate, why is that? Is it a language thing? I'm not English myself.

The act of evaporating condenses the solution- does that help at all? 8)

Edit my grammar is bad- the act of evaporation condenses the liquid.
 
anachronism said:
archeonist said:
In this post people use the word 'condense', when they actually mean evaporate, why is that? Is it a language thing? I'm not English myself.

The act of evaporating condenses the solution- does that help at all? 8)

Edit my grammar is bad- the act of evaporation condenses the liquid.
Uhm.. The act of evaporation evaporates the liquid :?
Evaporation is: liquid -> gas
Condensation is: gas -> liquid
 
If you put a pan of milk on a gas stove and simmer it- the water evaporates off, leaving you with condensed milk.
 
Don't know why they call it condensed milk, here in Sweden it is called "dried milk" (but in Swedish :D ).

In chemistry, heating a liquid is producing a vapor that when cooled condenses back into a liquid leaving the original solution concentrated in terms of dissolved salts. The cooler in a distillation setup is called a condenser. So I'm on Archeonists side in this debate.

I believe people started using condense instead of concentrate since the original poster did that. Maybe it's a language thing, English isn't my first language.

Göran
 
anachronism said:
If you put a pan of milk on a gas stove and simmer it- the water evaporates off, leaving you with condensed milk.

Ah Yes, I understand now, we also know this term in dutch: 'gecondenseerde melk' it is a language thing in many countries I guess 8)
 
archeonist said:
anachronism said:
If you put a pan of milk on a gas stove and simmer it- the water evaporates off, leaving you with condensed milk.

Ah Yes, I understand now, we also know this term in dutch: 'gecondenseerde melk' it is a language thing in many countries I guess 8)

Haha yeah it's good. I can see exactly why it could be difficult and that's why I used the milk analogy. 8) 8)

Jon
 
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