Non-Chemical Flux Melting

[golddie]

For the past few weeks I have been spending a lot of time in this forum
Chris and Harold have stated the importance of flux melting
If there is already a tread on this topic can someone give me the link or can someone give some details
Being in the jewelery business I have seen people melt gold and it would come out very clean
Also I have seen people that have destroyed what was already good
Thanks

 

[golddie]

I found this for starters

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=68&t=871

 

[4metals]

Chapman wrote a common sense paperback called how to smelt your gold and silver, it is available from Legend in Sparks Nevada, scroll down on the link and you will find it in their book section.
He discusses fluxes and does all of his melts in an assay oven.
http://www.lmine.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=assaying

Someone asked if it is available in pdf but I don't think it is.

 

[golddie]

Hi 4metals
Thanks for your help
here is a post i found to be helpful
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=63&t=1755&hilit=conversion+program&start=20

 

[Anonymous]

J.S. Wisdom , You Can Smelt Too a muct for your digital library. There are many flux formulas within.

 

[golddie]

Hi gustavus
I think i am going to take speed reading lessons.
If you have a link for that or a pdf that would be nice
I am just joking
I appreciate this pdf I like it a lot
Thanks

 

[61 silverman]

hi, I just attempted my second Inquarting with the same crucible,, The first go around my return weights were low, and the crucible had some green staining at the pour area. I recovered 3.74 grams of 5 expected.. I had pre-treated my crucible with a coating of borax. nice shinny surface..The material was 10k yellow gold added to it was fine silver for a total melt of 21grams...My second use of this crucible was a mixture of karat gold, gold filled material and a few grams of fine silver..The surface of the crucible still had a slick appearance, also had read of using this type of crucibles a number of times..was not worried about the crucible failing,, Did not think it was allready absorbing metals through its walls.
I was told that a mixture of 2:1 soda ash/borax should have been used as a flux, the soda ash actually feeding the borax to keep it from eating the crucible.. photos are after the second use.. There was only a small amount of molten metal I poured into water the rest in the crucible looked like red volcanic rock or something like that..View attachment 3[ attachment=0]100_0819.JPG[/attachment]

 

[qst42know]

Soda ash will eat silica. Helped along by base metal oxides. Looks much like a cupel.

 

[61 silverman]

thank's for that info qst42know, Not a cupel a regular crucible..here's a couple of better pics.View attachment 1
mark

 

[61 silverman]

here is a better pic of the gold that poured out and what was trapped in the crud.

 

[qst42know]

What is the question?

It looks like an ordinary fire clay crucible. These are produced in quantity to be cheap and in an assay lab environment these are usually used one time and in that context are considered disposable. You may have gotten one that is more porous than it should have been. I have heard of the used ones sold in bulk for PM recovery.

 

[Harold_V]

Heh!

I have melted thousands of ounces of gold, not only in the pure state, but when inquarting, and have had excellent results using white clay melting dishes. None of the described problems have ever been an issue.

It never ceases to amaze me how such a simple task as melting is complicated by folks, when it can be addressed so easily.

If a person is torch melting, I can't think of a worse vessel than a conventional crucible.

Harold

 

[goldsilverpro]

In a pinch, I have used 30 gram assay crucibles for torch melting. I first used a small hammer to break about 2/3 of the top part of the crucible away.

 

[Harold_V]

In a pinch, I have used 30 gram assay crucibles for torch melting. I first used a small hammer to break about 2/3 of the top part of the crucible away.

That would most certainly be key to success. Torch melting and crucibles don't go well together.

Harold

 

[61 silverman]

hi guy's thank for the reply's ,, this melt was in a neycraft oven .. heated to 2000 F
not trying to melt with a torch on this one,,,
I have melted with a torch in a melting dish here's a picture of the oven and my previous Torch and Dish melt's,,

 

[61 silverman]

This dish is called a scorification & roasting dish..
Harold I like the looks of yours with the pour spout formed I have been trying out the possibilities of making some melting dishes from ceramic or stoneware or even porcelain.. So far borax is the enemy of the ceramic..( Have not tried any SILICA with the flux ) Have not tried any metal without any borax,, worried about the metals just sticking not pouring out well.!!.Got that anyway...LOL

 

[Harold_V]

Harold I like the looks of yours with the pour spout formed

That is one of the second largest dishes that Vigor used to market. I have no idea if they are still available, but they are, hands down, the best dish for the money that hit the market when I was refining. Such a dish could be used and cleaned until it was so thin it would spring a hole in the side, or bottom. Using the larger size on a daily basis, for inquarting, I could get several weeks of service from the dish.

Borax is somewhat hard on dishes, but soda ash dissolves them (assuming they are silica) rapidly. To clean a dish, it is heated, then soda ash applied, along with fresh borax. The resulting flux is thin and liberates a button of alloy, which was previously tied up in the dirty flux. At the expense of some of the dish's thickness, it can be restored to new condition.

I understand your desire to make dishes, but considering the value of the contents when in use, and the fact that the white dishes are VERY stable once seasoned properly, it might pay you to abandon the quest and use those that are available commercially. That's assuming Vigor is still marketing the white dishes. Prior to finding the white ones, I had used the tan dishes, made in Mexico. They were very unstable, cracking even when they had been seasoned. I don't recommend them unless there are no other options.

I really like your Neycraft furnace. One of my customers had purchased one just before I sold my refining business. I recall that it was programmable, which is a wonderful feature for those that do burnouts.

Might not be a wise thing to use with flux, however. I expect it will be hard on the lining and the elements.
Harold

 

[61 silverman]

Thank's again Harold, going with the commercial dishes and crucibles is obiouslly my most intelligent choice.. Now I am a MONKEY SEE- MONKEY DO sort of Person, getting a proper season on a dish I understand is most imporant.. What are the proper steps to follow for very good results..and flux mix ..should a 2-1 silica - borax mix be used, That is what I was told at the Local Mining Store where I buy most all of my supplies..
The dish in my #2 picture I cracked while heating the first time I got the torch tip too close too soon and heard it crack then saw it , used the same dish a second time melted the largest button in my top picture also re-melted the smallest button. The crack didn't noticebly change..
Can you tell me why my material did not COME TOGETHER ? melt into a pool at 2000F?
44 grams 10-12-14K , gold filled material added , with a few grams of fine silver, 10 grams of gold expect as return...Placed in the crucible In The oven, no additional borax, after 1950F added 1/2 tsp Borax heated too 2000F poured out what would which in my pictures the flattened silvery white pieces are what was stuck too the walls and the bottom crushed from the coppery looking material.At 1950 there was a small pool of metal flowable..

 

[Irons]

Thank's again Harold, going with the commercial dishes and crucibles is obiouslly my most intelligent choice.. Now I am a MONKEY SEE- MONKEY DO sort of Person, getting a proper season on a dish I understand is most imporant.. What are the proper steps to follow for very good results..and flux mix ..should a 2-1 silica - borax mix be used, That is what I was told at the Local Mining Store where I buy most all of my supplies..
The dish in my #2 picture I cracked while heating the first time I got the torch tip too close too soon and heard it crack then saw it , used the same dish a second time melted the largest button in my top picture also re-melted the smallest button. The crack didn't noticebly change..
Can you tell me why my material did not COME TOGETHER ? melt into a pool at 2000F?
44 grams 10-12-14K , gold filled material added , with a few grams of fine silver, 10 grams of gold expect as return...Placed in the crucible In The oven, no additional borax, after 1950F added 1/2 tsp Borax heated too 2000F poured out what would which in my pictures the flattened silvery white pieces are what was stuck too the walls and the bottom crushed from the coppery looking material.At 1950 there was a small pool of metal flowable..

I suspect the base metal in the Gold-filled items is your culprit.

 

[Harold_V]

I suspect the base metal in the Gold-filled items is your culprit.

I'm inclined to lean that direction, too. I have never encountered a gold alloy, or silver, for that matter, that didn't melt and agglomerate well, particularly when a little borax was introduced.

You might also suspect that the white metal may have been marked silver, but it wasn't. That's not at all unusual. I had to check all silver that was submitted for refining, particularly if it was made in Mexico. All too often it was German silver, which, to the untrained eye, can readily pass for sterling. If that happened to be included, it doesn't melt at the temperature in question, but it does slowly dissolve. Also, an alloy of silver and nickel (German silver) tends to not blend well, so that could account for the lack of proper agglomeration. It would be difficult to know without the opportunity to do some testing. Again, if one torch melts, it's obvious that something is amiss, so the material can be stirred and superheated to insure all combines (for the purpose of inquartation).

61 silverman,

I hope this is read in the spirit in which it is intended. I certainly do not hope to offend those that have been giving you advice where fluxing is concerned.

I'm of the opinion that you are being instructed well for dealing with ores, but I see no useful purpose in introducing any silica when dealing with recycled metals. If you use only borax, you will have used everything that is necessary, and if you have performed your duties properly, the only real purpose it will serve is to "lubricate" the melting dish, so gold slides readily in the molten state, instead of sticking to the dish surface. Pure gold needs no flux------it needs flux only when it is contaminated. Flux, in that case, absorbs the oxide scale. You can see evidence of that when gold is melted. Pure gold does nothing to color the flux, although if you torch melt, it's not uncommon to see pink or purple coloration in the flux, the results of miniscule particles of gold (colloidal gold) being gathered by the flux. Discoloration, brown, green, blue, are signs of contamination.

Harold