sodium metaborate instead of borax

[jon_m]

Have some lab grade sodium metaborate from years ago. Wondering how it'd be instead of borax for a flux when doing my first gold melt down.

Read much from our forum and seems borax mixed with a lesser portion of sodium carbonate makes a good flux.

Just bought a mapp gas set from Aldi ($40 !) Yet to buy a crucible & tongs. Not a huge amount to melt down. Thinking of just a few grams per button to start with.

Sodium metaborate comes up as NaBO2 whereas borax (sodium tetraborate) is Na2B4O7. So If I have it right borax has more atoms of boron which is (is not?) the main ingredient in the flux.

Will it work? Or is it a 'maybe' and a risk. Don't want to start of on the wrong foot?

 

[Smoky bandit]

Dont know mate.
But borax is cheep and works well.

 

[davsgold]

G'day jon_m

The Mapp gas is fine but the flame torch that comes with it probably won't get hot enough as gold melts at 1060 deg C and that flame torch only get to " Flame temperature 1900F/1038C"

I know this for a fact as a guy bought a pencil flame torch from bunnings (well two in fact) and had them in each side of his furnace and it was there for half an hour and it would not melt, changed to the blow torch type on the mapp gas bottles and the gold was melted in about 5 minutes.

But hey you have it now and good luck, but if it is taking way long then just go to bunnings and get this one. I have used this type in dual into a small furnace and it worked. https://www.bunnings.com.au/tradefl...stainless-steel-blowtorch-with-piezo_p5910236

cheers dave

 

[Smoky bandit]

Map gas with self ignigting blowtorch head (2cm opening) ...borax and a crucible is all you need for button melts. This will melt 2 grams of dust and pickers in about 2 minutes.. :beer:

 

[davsgold]

Map gas with self ignigting blowtorch head (2cm opening) ...borax and a crucible is all you need for button melts. This will melt 2 grams of dust and pickers in about 2 minutes.. :beer:

yep, I do about 65 grams in a graphite crucible at a time and pour in 2oz block graphite mould, so even with two blowtourch going at once in the little furnace still nearly 5 minutes, and yes I add a bit of borax as it acts as a flux to catch any bits of quartz or dirt etc erfect:

cheers dave

 

[Manpa]

What you need for map gas is a swirl flame tip, this tip grabs aroundpipe giving a more even heat. Ideal for crucibles. Hottest point of the flame is approx 1/2 from the burner tip. These are the two hottest, highest btu output torches. (I sold Bernzomatic in Australia for 20 plus years)

 

[jon_m]

Thanks Smoky guess I'll just use some domestic borax. Was thinking that the lab grade stuff might be more efficient at removing debris. But should postpone trying it. Might be short of borons %#^%&

Manpa, do mapp gas replacement cartridges all have the same fitting? ie I note the Bunnings Tradeflame TF/Ultra mentions 1982. So thinking that if I cannot get a 'melt' then if the Bunnings cartridges can fit the Aldi torch I'd have a 2nd arrow.

The Aldi torch tip is ~10mm dia and seems to throw 3 flames around it - maybe similar to what you have mentioned?

Davsgold, the little furnace you have pictured; is that made of hebel? .... Thinking I could bodgy up something similar to put the little crucible in and hold more heat ...when it arrives

Thanks all

 

[7.62marksman]

I dont want to take over your thread but i will put it out there for everyone

if anyone needs some i have about 20kg borax and about the same in Soda Ash that i got for the supplier for the assey office (had to buy 20kg bags)
pm me and let me know

 

[Manpa]

Hi Jon M, the Tradeflame cylinder will fit your Bernzomatic torch head. When we were distributing Bernzo there was only one supplier of that particular style of cylinder and only one supplier of Mapp gas.
unless it has changed in the last five years Mapp gas (Methylacetylene Propadeine) is no longer available, it was replaced by Map gas (methylacetylene propylene)which burns slightly cooler 6C.

 

[jon_m]

The Aldi mapp gas ingredients are;
1-propene: 36-44 %
Dimethyl ether: 36 - 44 %
Propane: 18 - 22 %

Sounds like it will melt, but if not a new Bunnings cartridge should not be an issue.

What could help is a mini furnace/surround to have the crucible in & keep heat in. Would Hebel block suffice or is it likely to explode or crack up?

7.62 Thanks I have plenty of sodium carbonate, and should pickup some borax from the supermarket. But thanks and I do wonder if the supermarket borax will have any 'negative affect' ingredients added in?

Not having panned before, it seems that getting all or almost all the other minerals out of the specimens is the difficult thing to begin with. Quartz and light stuff comes out ok But gold flecked through ironstone doesn't seem to pan well, even before or after HCL its tedious.

So it'd be interesting to know how much of 'other minerals' to expect that the borax/flux can remove? And to this end, do I have it correct that re-melting with extra doses of borax will continue to purify the gold?

 

[Smoky bandit]

I use borax from woolies and melt ...2 to 3 gram buttons in a small crucible.
Turns out perfect every time. Yellow cartrige from bunnings $15..
Any impurities seem to go up in smoke :Y:

 

[davsgold]

Davsgold, the little furnace you have pictured; is that made of hebel? .... Thinking I could bodgy up something similar to put the little crucible in and hold more heat ...when it arrives

Thanks all

G'day jon

Yes mate, Hebel block, it was 200x200x600 from Bunnings $13 bucks and you can make three or four furnaces out of one block, the furnaces last a good while but eventually crack up, i then just crush up the inside part as a bit of gold does escape the crucible, same with the graphite crucible, when they get thin I also crush them and pan off the gold ready for next time.

Little Hebel furnace in action
[video=480,360]https://youtu.be/tW880L5LWkw[/video]

cheers dave

 

[jon_m]

Smoky sure hope the impurities go up in smoke. Think I've got a few. But maybe they'll clean up some more in the ultrasonic before melting, when it arrives.

Dave your video is a gem. And you have made it look very easy. I will definitely go this way. With my smaller volumes guess I'll get a button or 2 out before finding an empty gas bottle.

Thanks for posting the video. A lot of what I searched for were not so relevant.

Appreciate all the help.
Jon

 

[Smoky bandit]

The gold I find is from Gympie area so it's pretty pure.
And I think as I'm only doing small pickers and dust the impurities seems to just disappear into smoke. they come out nice and clean.

 

[nucopia]

Just did my first gold melt .
Started off by heating the small crucible and coating it with borax to get a good glaze.

Then tipped in all the fine Gold we collected from panning at Ophir last week, about 0.4 grams.

Took a little while to get the hang of things and I think I may have made a few errors.
Torch kept blowing out and needed to be relit and the glaze in some parts of the crucible has left a greenish blackish tinge also a very tiny )pin head size) peice of Gold was embedded into the glaze and had to be pried out .
Here is the result of my first attemt to melt Gold.

Button weighs 0.34 grams

 

[davsgold]

G'day nucopia

You'll soon get the hang of it mate, and yes I always save the glass flux when I remove it from the gold bar or button etc and keep that all for later, crush it again pan off and add the small bits and fines to the next melt.

I think that maybe the blow torch kept going out if the bottle outlet is on the down hill side, I find that the thing works better if the bottle is upright or at least slightly up hill if laying on it's side.

The little button 0.34g you can keep adding to it also next time if you want, when i have a partly completed bar I just put it back in the graphite crucible and add more small gold when doing the next melt and pour.

cheers dave

 

[nucopia]

Thanks Dave
Its certainly a learning curve thats for sure .
Any way i was able to melt a bit over half an ounce (16 grams) but i could not keep it melted long enough to pour the gold into the graphite mould.
Ended up with just a blob of gold.
Looks ok but ...
I must be doing something wrong and no idea what it is.. :8

 

[Goldchaser1]

Maybe needs another 5 minutes b4 ya pour it nucopia,gas still on when you removed the crucible? A mate had similar problems,he was turning the bottles off then pouring,cooling slightly and wouldnt pour correctly.....

 

[nucopia]

Gas was still on and heating the gold.
What would happen was , I would start melting the gold and get it into a liquide form and then while still it was liquified I would try and tip the crucible to pour it into the mould but the gold would solidify as it inched towards the spout.
Mayebe my fault in not keeping the flame constantly on the gold or not keeping the falme at the right distance to the gold or it could be i had too much borax in the crucible and it was sticking onto the bottom of the gold ??
Tried several times but each attempt gave the same result.

 

[davsgold]

It's not your fault and not the golds fault, what happens is, with the crucible your using is not getting hot enough, it actually needs to get red hot as well, and with it out in the open you can't get enough heat into everything at the same time, ( had the same thing happen with that type of crucible), that is why I made the little furnace and use the round cylindrical graphite crucible like in my video.

As you found out the gold cools to a solid very very quickly.

cheers dave