Removing Borax Trapped Gold from My Crucible

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Puff501

Member
Joined
Feb 15, 2020
Messages
23
Location
Arizona Desert
A week or so ago, I melted down my gold powder and turned it into shot. After glazing my crucible, I added the powder, and put more borax on the top, hoping to deter the powder from flying away. I got a good melt and made some nice shot. However at that time, I noticed there were a few very small beads of gold still stuck in the crucible in the borax.
Which leads to yesterday when I decided to try to melt some of the shot I made into a few gold bars using the same crucible. First I tried to make a 1/4 ounce round and failed 3 times to get it into the mold satisfactorily, so I gave up on that. Then I decided to make a couple 1oz bars, pre-weighed the shot to like 31.13g, did both melts and pours, and made 2 really nice bars for my first attempt at making bars.
Anyway, today I'm looking at my equipment and I notice all this gold still in the crucible, I hope you can see it in the pic. This I'm pretty sure it all got stuck there from the first meltings when I initially melted down my powder or maybe when I was trying to make the 1/4 oz gold round because the bar attempts came out right on as far as weight on one try. I don't have the 1/4 ounce round attempt anymore because I just turned that back into shot so I can't get a weight loss on that.
So now the problem I have is, how do I get the entrapped gold from the crucible?
 
Looks like you may have the torch up too hot/forceful. If you tone it down a bit you won't have all those beads sprayed all over the crucible. You also won't have so much of the violet hue on the crucible (that's gold). To get all the gold left in there you can use a collector. Just take one of the bigger shots and melt it. Have a tool that will allow you to roll around and manipulate the crucible collecting all the little beads.

For a complete and thorough clean out you can use a method I learned from Harold. Simply use sodium carbonate (ph up). This can be tricky as it doesn't like to melt. You need to get it hot enough to melt but not blow it out of the crucible. You'll again need a method of rolling the dish and use enough to get it to cover the crucible. It's super sticky like borax. It also removes material so you don't want to leave it on the same spot for extended amounts of time. Done correctly your crucible will be almost brand new. Best of all after it has cooled you can simply clean the crucible out with hot water.

ETA: that picture of the shot looks fantastic
 
Yes I'll consider the method of melting a bigger shot and rolling it around to do a collection.
The other concern is the gold that is stuck in the frozen puddle of borax in the bottom of the crucible. Will that gold down there be collected in the same way as all the beads on the sides?
 
Puff501 said:
A week or so ago, I melted down my gold powder and turned it into shot. After glazing my crucible, I added the powder, and put more borax on the top, hoping to deter the powder from flying away.
Click to expand...

When melting clean gold, you only need the slightest glaze on the dish. Adding more was a mistake. Even when molten, it's thick and sticky. That's why you ended up with a bunch of little gold beads stuck in the borax. Your shot looks nice.


First I tried to make a 1/4 ounce round and failed 3 times to get it into the mold satisfactorily, so I gave up on that. Then I decided to make a couple 1oz bars, pre-weighed the shot to like 31.13g, did both melts and pours, and made 2 really nice bars for my first attempt at making bars.
Click to expand...

Pouring a tiny bar or round is harder than pouring a larger bar. There's not much mass there, so it loses the heat needed to keep it molten very quickly. When you pour a larger amount, there's more thermal mass compared to the surface area that's radiating heat away, so it stays molten longer allowing it to be poured.


So now the problem I have is, how do I get the entrapped gold from the crucible?
Click to expand...

You can either thin the borax and remelt some gold to collect the tiny beads, or you can dissolve the flux out of the dish to free them. Since your dish appears to be in good condition, I'd opt for thinning. Fluorspar does a good job of thinning borax, but it does deteriorate the dish somewhat.

Dave
 
Ok so I will try remelting a half ounce or so and then trying to swirl to pick up all the stuck beads and hopefully clean up what's trapped in the bottom of the crucible as well.
I'll let you know how I make out with that.
Meanwhile I looked up Fluorspar.
Is it Calcium Fluoride? As in this pic?
https://ibb.co/D472FJf
 
You can also put the crucible in a beaker and use dilute sulfuric acid (10-20%) heat it to 180 F for 5-10 minutes. This will break up the borax and allow you to scrap the dish clean. Then you can re dissolve the gold in AR.
 
I remelted one half ounce and heated into a nice molten mass and slowly swirled to nearly to the rim going around maybe a dozen times trying to round up all the little balls trapped in the borax. Then I tried to give good swirling action over the mass in the bottom. That crucible was hot, red glowing hot. Swirled the sides a few more times and then I poured to make shot with it.
After cooling, I checked the crucible and there were still some balls stuck to the side though I don't think as many however the mass was still fully present on the bottom of the crucible.
So then I took 300 ml of distilled water and 70ml of 98% sulfuric acid, placed the crucible in the beaker with the solution and once it was up to 180F, i left it on the heat for 30 minutes. Almost all the balls had fallen off the sides to the bottom of the crucible and the ones that were still stuck, I just tapped with a glass stir rod and they came right off. The gold in the bottom mass of borax was still there and the borax was still hard. I carefully rinsed all the free gold and other loose substances from the crucible into a small beaker and after rinsing it off, put the crucible in a pan of water. I used a u-shaped wood carving tool to scrape through the borax to remove all the encapsulated gold. Working in the water, it came off easier than I anticipated. I scraped all the borax from the crucible.
I rounded up all the sediment and gold from the pan and also what I had in the small beaker and filtered it. I don't know how much it is yet but I'm thinking maybe 1/4 to 1/2 gram.
Thanks for your advice on this issue. Main lesson learned is to be lean on the borax. Nice thin glaze on the crucible is all I need.
Here's a pic of the filter
https://ibb.co/njtYKqW
here's a close up of the filter
https://ibb.co/KqJSqSR
It appears it was worth going after it.
Now I'm considering doing an AR on this. I'm wondering if only the gold will dissolve or if the other contaminants in there like borax, crucible, or carbon or whatnot will also go into the solution, or if all the other contaminants will stay out of solution to be filtered out.
Thank You
Puff501
 
AR will only digest the gold and borax leaving you with carbon and the melting dish material. Borax wont hurt anything and everything else will simply have to be filtered out.
 
I did my AR today on the crucible residue. I added 2.41g of super small bb's from my gold shot so as to have a decent amount of gold in the solution. AR took an hour and a half on a medium low heat simmer, I was surprised. I started with 50ml HCL and 4ml HNO2. Ended up adding 25ml of HCL and another 2ml of HNO2 to finish it up. It appears the pure gold beads I added were very hard to dissolve. It all dropped very nicely with maybe 2 teaspoons of SMB. I washed 5 times with distilled water and I did a HCL boil on it and rinsed a few more times. No more odor and the PH is 7. I'm going try to filter it out tomorrow, then melt it into a bead or more shot and see what my yield is. Going to glaze up a brand new crucible for this melt too. Will report when complete.
 
Well, I haven't melted it up but I dried the powder and have a weight of 2.37g. Interesting I have less than I started off with, .04 grams less. I thought I might lose some during the process but I thought I'd at least have a little bit more than the 2.41 shot I added because of the crucible recovery material I added.
Anyhow, we're good. Eventually I'll melt it up with the rest of my shot and make another 1oz bar.
Thanks for your help all.
Steve
 
Borax is water soluble. Simply boil the crucible in water. Length of time is subjective but be prepared to boil all day and perhaps the next day. Cost is heating source. The only time you should add acid is if the crucible has color other than pink or light purple. Black or green borax may need an acid added to dissolve the metal salts in the borax. Personally, I add a little HCl to clean my melt dishes as sulfuric acid can deteriorate the refractory in the dish.
 
Borax steals your gold. Use MB formula it’s a much better product.
mb-formula-melting-flux

Edit by moderator, this section are not for business related stuff.
 
Last edited by a moderator:
Jberger8 said:
Borax steals your gold. Use MB formula it’s a much better product.
mb-formula-melting-flux

Edit by moderator, this section are not fro business related stuff.
Click to expand...
That is not correct, it may hold on to your Gold if it don't coalesce correctly, but it will always be possible to get it back.
 

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