Excess borax

[Desk51]

I was melting my gold and I believe I added to much borax. I did add quite a bit. Definitely too much. If lefted me with a nice piece of gold covered in dark melted borax. Also I have another piece mostly borax with gold pieces on inside. So I went back to the melt dish and tried to re-melt the excess borax off. I had no luck. Also I’m using map gas torch. Is there a way to dissolve the excess borax off? Like in sulfuric acid or a nitric solution? I use nitric of soda as my nitric supply. If you could help, I would really appreciate it!
-desk

 

[FrugalRefiner]

It will dissolve very slowly in boiling water, much more quickly in dilute sulfuric acid. Be careful. Hot sulfuric acid is ferocious.

Dave

 

[Desk51]

Thanks Dave!
-desk

 

[anachronism]

Another useful point is that if your borax is dark, you're not cleaning your gold enough. Read up on cleaning, it'll help.

Jon

 

[Williamjf77]

When you say not cleaning the gold enough do you mean the washing of the powder before melting or from metallic impurities?

 

[anachronism]

When you say not cleaning the gold enough do you mean the washing of the powder before melting or from metallic impurities?

The two go hand in hand. Correct cleaning of the powder takes out a very high percentage of the base metal that co-precipitates. The main one being the copper residues because that's mostly what is dragged down. It's all linked because black flux tends to be copper impurity in the majority of cases and as mentioned that's the main thing that's dragged down with SMB or Ferrous Sulphate if your pregnant solution has been filtered to clarity prior to dropping.

Good cleaning is an aggressive action though which often results in a small amount of your gold being dissolved back into solution but you can just precipitate that out again so it's never lost. Cleaning very small amounts of precipitated powder isn't very practical and I would always recommend putting a few small batches together to make the process more efficient.

A good clean done properly can easily give you three nines gold even from a really dirty solution.

At three nines purity your flux will hardly change colour if at all. Your ideal situation is to have clear flux (using very little borax) and a slight red tinge to the dish.

 

[rickzeien]

When you say not cleaning the gold enough do you mean the washing of the powder before melting or from metallic impurities?

The two go hand in hand. Correct cleaning of the powder takes out a very high percentage of the base metal that co-precipitates. The main one being the copper residues because that's mostly what is dragged down. It's all linked because black flux tends to be copper impurity in the majority of cases and as mentioned that's the main thing that's dragged down with SMB or Ferrous Sulphate if your pregnant solution has been filtered to clarity prior to dropping.

Good cleaning is an aggressive action though which often results in a small amount of your gold being dissolved back into solution but you can just precipitate that out again so it's never lost. Cleaning very small amounts of precipitated powder isn't very practical and I would always recommend putting a few small batches together to make the process more efficient.

A good clean done properly can easily give you three nines gold even from a really dirty solution.

At three nines purity your flux will hardly change colour if at all. Your ideal situation is to have clear flux (using very little borax) and a slight red tinge to the dish.

That is some solid advise. I think I have learned more about smelting (or in this case melting) by analyzing my slags then from other means.

Sent from my SM-G950U using Tapatalk

 

[kurtak]

because black flux tends to be copper impurity in the majority of cases

Black slag indicates iron

Slag colors -----

lead = yellow

magnesium or zinc = gray

copper = red (depending on the make up of the flux high copper slag can sometimes be a turquoise shade of blue)

cobalt = blue (as in the deep cobalt blue)

tellurium or selenium = can also produce a "cherry" red slag

antimony = yellowish green

manganese = purple

iron = dark brown to coal black

keep in mind that the color of the slag is determined by the element that is greatest in the smelt/melt

in other words the slag wont have a little of one color here & a little of another there - rather it will tend to the color of the predominant metal oxide going off in the slag

Kurt

 

[rickzeien]

Great primer on slag

Sent from my SM-G950U using Tapatalk

 

[butcher]

The color of borax is used in testing, one of many methods of determining metals, or salts of metals...

https://en.wikipedia.org/wiki/Bead_test
http://www.webmineral.com/help/BoraxBead.shtml#.XcbgJjNKjcs

 

[anachronism]

Any time my flux is black or "dark" is copper contamination Kurt. I don't have iron in any of the gold. Then again in all fairness it's a while since I've had dark flux to be fair. I'll go with dark turquoise rather than black for sure.

The red around the dish isn't copper though I'll stand by that one mate. 8) 8)

 

[kurtak]

It will dissolve very slowly in boiling water, much more quickly in dilute sulfuric acid. Be careful. Hot sulfuric acid is ferocious.

Dave

Dave - that works fine when there is a "little" bit of slag (borax) stuck to your gold & even then it is slow

In the case of Desk51 he has a LOT of borax stuck to &/or with his gold so that's just not going to work as it is more likely that hot water &/or sulfuric will take daaaays to dissolve the borax

Desk51 - in the case of the larger piece of gold (depending on how big it is) I would just beat it with hammer to chip "most" of the borax off - even to the point of flattening the piece of gold out - put it in a plastic bag or in a rag so it doesn't go flying off when you hit it with the hammer - the borax (being sharp) will cut holes in the bag or rag so move it around in the bag or rag when holes develop

Then (there will still be "some" borax stuck to it) you can dissolve the remaining borax off with the hot dilute sulfuric method --- or better yet put it in a new "properly seasoned" melting dish & re-melt it (properly seasoned dish is important here)

concerning the small beads of gold stuck in lots of borax - again it depends somewhat on the situation (pictures would be very helpful) but I would likely bust it up (hammer method) make it as fine a powder as possible

Depending on the gold bead size you MAY be able to just sort the beads out & then re-melt them as above

if the beads are to small to sort out - mix the crushed borax (& gold) with sodium carbonate ( also called soda ash or washing soda) 60 -70% soda ash to 30 - 40% borax & re-melt it --- may take several melts due to the increased volume of flux by added soda ash --- when the flux is molten pour it SLOWLY (keeping the torch on it to keep it molten) into a large pot of cold water

the soda ash makes the borax water soluble - you may or may not have to heat the water &/or stir it to get it all dissolved

depending on base metal oxides these oxides may remain after the flux is dissolved - you can wash pan) most of that off - then re-melt the beads in a properly seasoned dish as described above

Kurt

 

[butcher]

Relatively pure gold will leave a pink hint to the borax in a glazed dish.

You really do not need borax to "flux" (or make fluid, and to absorb metals oxides) when melting pure gold.
Just glazing of the melting dish is all that is needed to keep the gold from sticking to it.

If you are using a lot of borax and melting impure gold you are fluxing the gold in the borax...

Impure gold, when melted, can form base metal oxide coatings. As the gold melts you may form many of these very small beads with oxidized shells which are less likely to join together in the melt to form a larger button, now put that in a river of borax, where the borax is absorbing the molten metal oxides to form borate glass, add to that a lack of high enough heat, or time, or fluidity of the flux (borax along with other base metal oxides or metal salts involved in the melt), along with the chemical reactions of these base metals in the melt ... you get a river of borax with small beads...

Metals and base metal salts will go through chemical reactions with each other in a fusion of the metals and their salts, The melting process and will also chemically react with the borax or other flux ingredients or atmosphere at the high temperatures of melting or of smelting process...


If you are using borax to flux impure gold in the melt you may need to add other flux ingredients, such as glass or silica, maybe an oxidizing or reducing agent, thinning agent, all depending on the contamination of the gold and the conditions of the base metal salts involved...

 

[kurtak]

You mean the "pink" around your dish don't you :?:

And you are right - the "pink" is not copper - it's gold :!:

I can say that because I have actually seen you melting gold :wink: :twisted: :mrgreen:

Kurt

 

[kurtak]

Relatively pure gold will leave a pink hint to the borax in a glazed dish.

You really do not need borax to "flux" (or make fluid, and to absorb metals oxides) when melting pure gold.
Just glazing of the melting dish is all that is needed to keep the gold from sticking to it.

If you are using a lot of borax and melting impure gold you are fluxing the gold in the borax...

Impure gold, when melted, can form base metal oxide coatings. As the gold melts you may form many of these very small beads with oxidized shells which are less likely to join together in the melt to form a larger button, now put that in a river of borax, where the borax is absorbing the molten metal oxides to form borate glass, add to that a lack of high enough heat, or time, or fluidity of the flux (borax along with other base metal oxides or metal salts involved in the melt), along with the chemical reactions of these base metals in the melt ... you get a river of borax with small beads...

Metals and base metal salts will go through chemical reactions with each other in a fusion of the metals and their salts, The melting process and will also chemically react with the borax or other flux ingredients or atmosphere at the high temperatures of melting or of smelting process...


If you are using borax to flux impure gold in the melt you may need to add other flux ingredients, such as glass or silica, maybe an oxidizing or reducing agent, thinning agent, all depending on the contamination of the gold and the conditions of the base metal salts involved...

Good post & correct --- or as Jon said earlier - if you do the proper washes of you gold in the first place - you don't need borax to melt your gold - other then the borax used to glaze (season) your dish

the links in your other post where awesome - thanks for posting them

Kurt

 

[anachronism]

You mean the "pink" around your dish don't you :?:

And you are right - the "pink" is not copper - it's gold :!:

I can say that because I have actually seen you melting gold :wink: :twisted: :mrgreen:

Kurt

True. Excuse me for being harsh but time over time I am told that moderators on this forum are "here for their ability to moderate rather than their ability to refine." However I am probably remiss but people take their refinery knowledge as gospel. Us guys who actually do it are sidelined when a green name pipes up.

Edit: Can't be bothered.

 

[g_axelsson]

As I can't refine gold I'll just post a picture as an illustration... :mrgreen:



There's a bit of a black line in the borax, but I think it's actually soot embedded in the borax and not copper. I use an acetylene torch for melting.

Göran

 

[butcher]

Excuse me for being harsh but time over time I am told that moderators on this forum are "here for their ability to moderate rather than their ability to refine." However, I am probably remiss but people take their refinery knowledge as gospel. Us guys who actually do it are sidelined when a green name pipes up.

Since you were are excusing your being harsh in your opinion.
Excuse me while I will be blunt.
Are you questioning my ability to refine, or the knowledge behind what I have to say as a member here on the forum?

I do recover and refine and my product is of professional quality, I do not refine for the public or for-profit as a business, I have worked hard to gain my knowledge and to improve my skills in refining.
True I came here like others to learn and to share my knowledge with others of what I have learned. I came here to learn the skills of a professional refiner and have spent years improving my skill and knowledge.

I also enjoy learning from all of the other members like moderators who were not professional refiners, Moderators who were professional refiners, New young members who started out as backyard scientist and became professionals at refining after joining the forum, new members with knowledge or experience different from mine, I take information from any member of the forum no matter what color the login name or how many posts counts they can tally up with a whole bunch of talking...

No one should take anyone's word as gospel no matter if they have some electronic scrap business or not. if they recover gold for profit or not, or if they were a moderator of the forum neither of these is any guarantee of facts, or of knowledge.
Facts and knowledge are easily proven, the sources of viable and relevant information easily become recognizable.
Educating yourself is the best way to know good information when you see it no matter the source of the information, then verify that information...
Are you saying that we should only take advice from moderators who refine for the public (even if they learned their skills from the forum), or from the members who run an E-scrap business or buy circuit boards and ship them to China for recovery?
No thank you I will learn from every member here ( something or another), no matter how many posts they make or if they run some business, or if they are learning just as I am.

Jon I do not think members count that much on the color of your name or if you run a business or not, or by how many posts you rack up, or how well you believe your recovery or refining skills are better than other members...

 

[butcher]

It looks just like professionally refined gold to me, but what would I know about gold?

I am just some old miner, who came here to learn to recover and refine gold, and improve my mining skills as a hobby and got stuck with a green name and a job of trying to help members keep the peace and have a good place to learn and share what they learn.

 

[anachronism]

No Butcher I am not questioning your ability to refine.

I'm articulating (badly) the frustration of giving advice to new members and the new members only seeing the advice from people with a green tag as relevant.

Jon