Removing Gold From Borax

chawimac · Sep 15, 2009

I am using a Kerr Maxi Electromelt 100 Oz. furnace with a graphite crucible to melt 2-3 Kg. gold bars from scrap jewelry, quite successfully. The problem I am having is with Borax. I am unsure of how much borax I should be using. Currently I use 1-2 spoonfulls per 2 Kg. batch. I worry because I have a nice bag full of borax with millions of tiny dots of gold.

Without using acids, how can I get the gold (and diamonds I suppose) out of the Borax to re-melt and sell?

I'll post pictures if it helps but I am assuming you guys know what I am talking about.

Platdigger · Sep 15, 2009

Smash it up a bit, dissolve it in water.
Heat if needed.

Fournines · Sep 15, 2009

You could remelt the borax that has the gold "dots" in it. Let it cook for a little while. All of the little gold pieces should pool together once you pour the molten borax into a mold, after it cools, break the borax away and you will have a little button.

As for the diamonds, they're going to be worthless once they've been put through a melt and captured in borax. Most little diamonds are not worth much right now anyhow. Here in New York you can sell them for maybe $25-50 per carat.

Last time I checked anhydrous borax will not dissolve in water platdigger, you are maybe confusing that with laundry borax? :lol:
http://www.home-ec101.com/wp-content/uploads/2007/05/concert-001.jpg

4metals · Sep 15, 2009

Break up your flux so the pieces are small enough to react with a few more ingredients you will be adding in the old flux and do a flux melt. To the borax add some soda ash equal to the amount of crushed up old borax you have started with, add an equal amount of Borax (always use anhydrous) and about 1/4 part fluorspar (calcium fluoride) this will really thin the flux. Easy on the fluorspar it eats up crucibles. Now heat it up to melting temperature.

Now pour the molten flux, which will be much less viscous than before, into a cone mold. The beads will collect on the bottom of the mold and are easily separated from the slags. Cone molds are valuable tools, often overlooked, but they make collection of the beads you have entrapped in the slag much easier.

It has been my experience that diamonds that have been fluxed and melted are worthless but Harold has had different experience and his input here may teach us all something.

Platdigger · Sep 15, 2009

That's right Fournines, I have done this with the laundry type.
I thought the only difference was the moisture content.

4metals · Sep 15, 2009

There is much confusion about borax, mostly because it comes anhydrous and is called borax glass, and it also comes with "10 waters" which is what is sold as a laundry soap, it's referred to as Borax as well but it is almost half water by weight Na₂B₄O₇ · 10 H₂O.

Bottom line is after about 760° C the waters are gone and it's all borax glass. On its way to becoming dehydrated, it swells and can overflow your crucible, that is why borax glass is best. But after it has seen the heat it's all the same.

chawimac · Sep 16, 2009

I get my Borax from a chemical supply, and it comes in a clear bag sold by the pound. I assumed it was anhydrous, but after reading 4metals post I see it is not. When I place Borax on a warm crucible it fluffs up like popcorn! The crucible needs to be red hot for the Borax to immediately melt and have the water evaporate, thus I have laundry borax!

I do not have a cone mold, but I have tried re-melting all my borax to get gold out of it. I got a few grams but the flux is still full of tiny gold particles.

I tried heating the Borax in water but was unsuccessful. I will get the soda ash and try the recipe. Just one question on that though. It's 1 part old borax, 1 part soda ash; to that mixture (say it came out to 100 grams) I add 1 part (100 grams) anhydrous Borax and 1/4 parts fluorspar (25 Grams). Is this correct? I heat to say... 1750° Fahrenheit, stir and pour. Correct?

4metals · Sep 16, 2009

That's the mix for old borax in a remelt but for just melting karat gold use 2 parts borax, 1 part soda ash, and 1 part fluorspar. That will make a nice fluid flux that shouldn't hold up your beads. Check into cone molds they're not too expensive, check out Legend in Sparks Nevada they have them. http://www.legend-reno.com/

I have also seen cone molds homemade by welding 4 triangles of steel into an inverted pyramid, never used one but it should work. Anybody made one?

Harold_V · Sep 16, 2009

4metals said:
It has been my experience that diamonds that have been fluxed and melted are worthless but Harold has had different experience and his input here may teach us all something.

My experience with diamonds was limited to those recovered manually from jewelry prior to melting. The exception to that was a large number of small diamonds that got through the screening process when screening polishing wastes. That material was run through my ball mill so it could be shifted to basic via the addition of adding lime. It was then processed with cyanide. This, of course, was after it had been processed with AR.

Small diamonds went through the ball mill unharmed, and were recovered when the discharged material was classified. Amazingly, diamonds were not harmed. While a few came out chipped, I concluded that they were likely discarded because they were chipped. I drew that conclusion because of the small percentage that was harmed as compared to the large number that were not.

I was selling full cut melee for $200/carat at that time, so it was worth the effort to recover them. Busted or otherwise damage diamonds could be sold for $25/carat. Diamond in any form has value, even diamond powder.

Harold

Harold_V · Sep 18, 2009

4metals said:
There is much confusion about borax, mostly because it comes anhydrous and is called borax glass,

Borax glass is borax that has been melted and granulated. Anhydrous borax has no water (well, almost no water) and has not been melted. They both do the same job, but they are not one and the same, although I believe them to be, chemically. I've used both of them with equal results. Anhydrous is opaque. Borax glass is somewhat translucent.

and it also comes with "10 waters" which is what is sold as a laundry soap,

Five waters, too. I can't recall which one I used, but it was one of them when I ran my waste materials in the furnace. Damned stuff froths up like crazy! :lol:

Harold

chawimac · Sep 18, 2009

Here are the gold bars that started the thread in the first place! 2Kg Each.

nickvc · Sep 21, 2009

re running your fluxes is an essential operation especially if your doing volumes of melts. One thing i would suggest after remelting and removing the visible beads would be to throw your waste flux in an old/new concrete mixer with some steel balls & blocks put a thick plastic sheet over the end and tie it down switch it on and crush it 2 a fine powder & sieve it, this will remove beads of metal & stones. You can also throw your old crucibles in. this is noisy but putting rubber matting under the mixer makes it more bearable and if you run batches of say 10 kilos it only needs doing periodically. The powder is worth assaying & will have a value which you can trade or recover yourself if you have the time or interest.

chawimac · Nov 16, 2009

Your formula worked great for me. Thus far I have removed over 80 grams of gold. The mixture you recommend works far better than simply using borax when melting. I highly recommend it to all in this forum. Thnx again.

dtectr · Sep 29, 2010

Wouldn't hot sulfuric acid dissolve the borax residue? From what I've read, I believe that's
what many here use to clean up their "beautiful" buttons & ingots after melting. I've not done this, myself.
Just asking.

philddreamer · Jan 16, 2011

Hi dtectr!

It's true, a boil in 10% sulphuric will clean the borax off the buttons & ingots, but they are referring to cleaning the borax from the melting dish & crucibles.

I'm trying to find a flourospar supplier in Seattle...

butcher · Jan 16, 2011

Phildreamer, apparently feldspar is 60% of the earth's crust, I am just not that good at Identifying rocks, maybe Rock Man can help us out.
guess I have been looking for the wrong rock?

http://en.wikipedia.org/wiki/Feldspar

I would also like to Identify this rock in my area for use as flux.
maybe go looking in the dark with a blue light?
http://en.wikipedia.org/wiki/Fluorite

Harold_V · Jan 17, 2011

Might have a little better luck with the correct spelling. It's fluorspar, not flourspar.
Hope this helps.

Harold

4metals · Apr 13, 2015

The moderators would like to thank all of the members who contributed to the original thread that this post was based on, as well as those who asked questions showing what was missing. Because of the extra length and interest in this thread we have created the above, consolidated version making for an easier read. We encourage all members to read, comment, and ask questions in the original thread, Removing Gold From Borax.

The Library threads should not be considered to constitute a complete education. Instead, they're more like reading a single book on the subject of recovery and refining. There is so much more information on the forum, and it is impossible to include it all in these condensed threads. Members are strongly encouraged to read the rest of the forum to round out their education.

For those who prefer a printed copy, a pdf file of this thread is provided below.

Removing Gold From Borax

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