Refractory Clay for Crucibles & Furnaces

[Tathradj]

Might be a good idea for a sticky or subsection.
"How to smelt your gold into one piece without using Mercury"
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Mods, Harry?.
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Sorry for wording. Brain not active at moment. Thinking about fibreglassing today

 

[Dr4gul3]

please tell me you guys are not playing with mercury haha

 

[KarlS]

please tell me you guys are not playing with mercury haha

Yes we do. All of you experts, stop this constant nagging about this and that. Most of people here aren't idiots, can read and don't need constant reminders that every time you pass within half a mile of drop mercury or lead you will drop dead.
Karl

 

[Tathradj]

Karls,
I did not mean it to sound like that.
It is hard to get for some and having an easier way of doing it makes sense to me. Yes, I have done the "Irish Potato Bake" my self before a few times.
Can not get the stuff now.

 

[Dr4gul3]

please tell me you guys are not playing with mercury haha

Yes we do. All of you experts, stop this constant nagging about this and that. Most of people here aren't idiots, can read and don't need constant reminders that every time you pass within half a mile of drop mercury or lead you will drop dead.
Karl

easy there Karls,
I wasn't trying to have a stab or anything - my experience with mercury has never been by choice, and if I hadn't been as cautious of suspect jobs I could have been up sh*ts creek, so I never take the element lightly - I guess it all comes down to personal opinion.

that said, I am still a nooby, and if there are any threads regarding the use of Mercury I would be keen for a read.

 

[KarlS]

Mate I'm pushing seventy and I'm getting bit tired being lectured every few weeks about dangers of this and that. We been thru this topic on this forum over and over. Yes , mercury can be dangerous to your health. But most of it is just common sense. Would you burn plastic bags and other plastic rubbish and inhale the smoke. Most likely not. Some of those fumes I'll kill you faster then mercury.
Karl

 

[KarlS]

Tathradj
I did not have go on you mate, it's just that I'm getting tired of all that expert opinions. According to it I should be six feet under, long time ago.
Maybe your idea of sticky is good, it may stop some future lectures about mercury.
Karl

 

[Tathradj]

All Good Mate. LOL
No offense taken.
Actually a good idea.

 

[Barra_Mad]

hey as said before might be best just to get a coffee can furnace. you can get these on ebay and they work a treat.

http://www.ebay.com.au/itm/Miners-P...910?pt=LH_DefaultDomain_0&hash=item487e4697ce

might be best to buy rather than try make crucibles they don't cost much try Rowe scientific for a bulk order

 

[Wombats1]

we used to use a cement called from memory "Fondu" it was black, it was used to repair what we called fire boxes in clay roofing tile Kilns, the fire box would bear the brunt of the gas burner. it was hot enough in those that the glaze was like glass it would penetrate the white fire bricks and melt them, nightmare to chisel out , the fondu was used to strengthen (slow down oxidization i presume) the inside of the box with a layer of render. the boxes themselves were mortared with clay the same as the tiles were made of. hope this helps.

 

[jethro]

Hey guys thought I had better touch base & clarify exactly what I,m trying to achieve.
For some time now I,ve been interested in the many small hardrock shows that were opened up in the hills between the murray river & the great divding range. I started out by just picking up a few pieces of quartz of the mullock tips of one of the major mines in the Bethanga area. I dollied it and washed it and to my surprise there was a couple of specks of gold. That was 25 years ago. Anyway ever since then Ive been testing the quartz / veinstone that was left behind on dumps and under dollying trees and even on old dray & sled & barrow tracks. I have found some good stone & Ive found some barren stone but on average ive found more gold bearing stone than barren stone.
Ive become very interested in one particular area (partly due to distant family connections) and the varied geology of the reefs encountered. I started out bringing home samples off the dumps in the area & breaking them down with a pnuematic hammer and a dolly pot, toooo slow. Next came the rod mill tooo noisy.
Anyway Ive almost completed building a flail hammer mill (pics & thread when its ready to go) which will be used in conjuction with the rod mill to grind the ore down to about 100 mesh or finer., then it will be concentrated on a wilfley table yet to be built & finally roasted to oxidize the sulfides & smelted in a crucible to liberate & consolidate the very fine goldthat is present in the ore from this area and purified using a cupel.
Some of the mines were very rich, one going 10oz to the ton throughout & many others averaging 3oz to the ton. Another in another area about 10kms away went 1000 grams at the outcrop according to mines dept records I have nt found this one yet but have figured out which gully it was located in by researching old newspaper articles on trove. All the mines were high in sulphides so a lot of gold is locked up in the sulphides, hence i need to roast the concentrates. hope this gives you all a bit better idea what im up to.

 

[Dr4gul3]

do you know what kind of sulfide material it is? arsenopyrite would obviously be quite dangerous. but I was thinking if there is any antimony present when you cupel the final smelt you may oxidise some of the gold along with the lead.

I have had this happen to me quite a few times, though it wasn't quite as much a big deal as I was cupelling large amounts and the loss was negligable over all, but if you are only cupelling smaller amounts it may cut into profits.

 

[jethro]

hey DR thanks for the heads up, I didnt know about antimony sulphides causing gold loss through oxidation / volitization. Unfortunately some of the ore I have is very high in arsenopyrite so the roasting will need to be done away from other people & animals.

 

[Greenhornet_au]

So Jethro did you find your source for 'refractory clay' or mortar ?

I have had access in the past to mortar that is used in glass bottle furnaces - making glass bottles.
This is used to bond components of refractory brick and has a temp rating of 3500 C.

But is only in 20kg bags.

 

[AtomRat]

That sounds like some good cement greenhornet. I was able to find high temp refractory jethro in ceramic and pottery supplies closeby, but i still recon for gold temperatures and for a crucible to last, pressed is better. Graphite & refractory clay pressed into a solid mold