Hey guys, wasn't my doing but a guy brought me some borax that he had melted scrap gold in with diamonds in the gold. We have an agreement to split the diamonds and gold if I can get it out for him. I have recovered gold from borax many times with no problem, however, I do not want to melt and add soda ash or fluorospar to thin it and risk burning up the diamonds (if they aren't already completely gone, however going through a sample of it shows that at least enough diamonds survived to make it worth it). I know water can dissolve a lot of the white borax powder, but the more glassy melted stuff will not dissolve in that. Is there an acid I can use to dissolve the rest of it? I know from experience that sulfuric is not very good at doing this. Any help is greatly appreciated.
how to dissolve melted borax chemically
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Boil the borax in water, really boil it, not just hot. While it is still very hot decant the liquid which will have dissolved 80 to 90% of the borax. Let it cool and the borax will crystallize out and the water is poured off. It probably takes about 1 1/2 gallons of water per pound of slag.
The stones are picked from that fraction manually. From there you can melt with thinning flux or put the whole thing in aqua regia. That will dissolve the gold which you can refine normally and leave less to pick through. Usually a quick check will tell you how much of the metallic looking material is in the remaining borax, if it is significant use the acid, if minimal pick the stones and melt.
The stones are picked from that fraction manually. From there you can melt with thinning flux or put the whole thing in aqua regia. That will dissolve the gold which you can refine normally and leave less to pick through. Usually a quick check will tell you how much of the metallic looking material is in the remaining borax, if it is significant use the acid, if minimal pick the stones and melt.
Well when 4metals posts we all listen, he is definateley one of the stars of the forum full of brilliant advice and ideas 8)
Gee Nick, it's only hot water!!!
Some refiners do it for a lot for customers. Please note most of my pictures of refining equipment / setups are taken when they are new, before a lot of use. These tanks and stoves won't stay so pretty for long.
Some refiners do it for a lot for customers. Please note most of my pictures of refining equipment / setups are taken when they are new, before a lot of use. These tanks and stoves won't stay so pretty for long.
Barren Realms 007
In Remembrance
4metals said:
Yes so true but you keep so many out of it so often.
Topher_osAUrus
Well-known member
4metals said:
Beautiful!
As we say around our place--it's stainless not stainfree. 304/316 rusts even when you turn the air over 4-5 X/hour in the whole facility and more in certain areas.
In the refinery, tantalum and titanium are what hold up. Ta is what we patch our glass lined stuff with.
And yes, 4metals is a refining rockstar. Diamond pun intended.
In the refinery, tantalum and titanium are what hold up. Ta is what we patch our glass lined stuff with.
And yes, 4metals is a refining rockstar. Diamond pun intended.
Yes Lou, besides you and a few others he is definitely one of my favorites on here!
I am sure I could have said "one of our favorites"
I am sure I could have said "one of our favorites"
My scuba class did their checkout dives in salt water. Dive gear was stowed overnight in slatted, wooden lockers. Many of us were shocked to find rusty spots on our stainless steel dive knives the next morning! Even simple salt water will destroy stainless. Stainless not stainfree or rustfree.Lou said:
Dave
jason_recliner
Well-known member
Well I just think it's extraordinary. That one can pose an off the wall question like this and have a concise answer from surely one of this planet's most knowledgeable on the topic - in TWENTY FIVE MINUTES. If I were trying to find an answer from my telco, I would still be on hold.
autumnwillow
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You could remove borax by either of the following:
Mix 100ml sulfuric(98% grade) with 900ml water (tap water will do) - always add acid to water.
Or you could use sodium bisulphate in 300g/1000ml.
Put in a glass jar, submerge your items and let it sit in there for 30 mins. This should dissolve all the borax. Remove your pieces or filter.
You could speed up the process by adding 50ml 3% hydrogen peroxide or by adding a low heat to the glass jar. Make sure you are using a glass jar capable of withstanding heat.
Mix 100ml sulfuric(98% grade) with 900ml water (tap water will do) - always add acid to water.
Or you could use sodium bisulphate in 300g/1000ml.
Put in a glass jar, submerge your items and let it sit in there for 30 mins. This should dissolve all the borax. Remove your pieces or filter.
You could speed up the process by adding 50ml 3% hydrogen peroxide or by adding a low heat to the glass jar. Make sure you are using a glass jar capable of withstanding heat.
First hot water, then maybe pickle.
Truth be told, if you want it to go quick(er), a pressure cooker will get more borax into solution mo' faster.
Truth be told, if you want it to go quick(er), a pressure cooker will get more borax into solution mo' faster.
Lou said:
While a little pressure never hurts, I know of 1 situation where boiling Borax in a pressure cooker did. Let me preface that by saying most refineries are difficult to keep spotless clean like the labs we all dream about, but the fact that under the heat and pressure the borax that dissolved in the water can become supersaturated, its desire to come out of solution is high and the familiar crust will form easily. This refiner's crust formed in the neck that has that steel disk that bounces around on the steam pressure exit point that releases pressure and blew the pressure cooker off the stove and split a side open. He essentially boiled the liquid in a sealed container.
Unwillingly, but Boom is Boom no matter how you slice it.
If you want pressure, keep things clean and crust free because Lou is correct, it works mo' faster.
Eek. I merely suggest it as a polish step.
A
Anonymous
Guest
Lou said:
Dude seriously..... chastise yourself for your slip up hehe 8) 8) 8)
Well, the inquiring minds who want to know have quite a bit of this material with a substantial sum locked up in it.
Time was when certain uninformed neophyte karat buyers were melting the karat with the stones still in it, some of the diamonds burn and get hazed, some get stuck in the slag and are largely protected. After the bum rush subsided, everyone got wise about the diamonds' value.
In practice, essentially what 4metals recommends is what can be done, but there are other more expedient routes that of course are more expensive and dangerous...
Time was when certain uninformed neophyte karat buyers were melting the karat with the stones still in it, some of the diamonds burn and get hazed, some get stuck in the slag and are largely protected. After the bum rush subsided, everyone got wise about the diamonds' value.
In practice, essentially what 4metals recommends is what can be done, but there are other more expedient routes that of course are more expensive and dangerous...
Cryogaijin
Active member
I have a big 10mm round ruby I've sent through my furnace a half dozen times. . . Gunna put it through nitric next. (It is a flame-fusion ruby, gem grade, but very inexpensive. I am mostly testing how delicate I have to be with them.)
May have to invest in a pressure cooker, as flux is driving me nuts at the moment. A kaboom is unlikely considering how little material I actually go through.
Connie Saxe
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Although the reply threads go all over the place on various subject matter, the question was "how can you dissolve borax slag in order to recover dispersed fragments of metallic value " (don't worry about the diamonds, they will be just fine, as long as you do not introduce excessive heat and/or hydrofluoric acid)......... this is a common gold-extraction processing problem, absent the diamonds).
Borax is water soluble. The ancient rule, "water verses anything, water always wins", can apply here if you have the time to wait. Boiling water works faster. It is always nice to use non-toxic methods that do not obscure your metallic results. Acetic acid (vinegar) is a little quicker method which I use frequently especially when I need to step-wise microscopically examine the slag for melting characteristics (ie how well the melting process proceeded and what metals might have been in the rock - especially Platinum and Iridium).
So, usually after a rock-extraction melt (quartz, feldspar rock containing gold, silver, copper), where you add lead oxide and let the melting /heating process proceed in order to burn-off unwanted metals - the recovered fragments of metal left in the slag may not be in nice, neat buttons. What you might have is thousands of tiny fragments of gold/silver. Once you dissolve-off the slag, wash away all the acetic acid with water - then you can add nitric acid 70% to the container holding the thousands of tiny gold/silver metal fragments - nitric acid will dissolve the silver and remaining copper - leaving fairly clean gold. Once nitric acid treatment completes, wash off the gold and either melt it or dissolve it in aqua regia for a re-recovery purification.
Welcome to the forum Connie.
To be clear, he was asking how to get the diamonds out of the slag without remelting the slag with a thinning flux and possibly ruining the diamonds. I know this because I personally know the asker of the question.
Just an aside, diamonds and HF are fine. Nothing happens, boiled them in it I don't even know how many times.
