What Is Flux??

[Geo]

I am interested in a flux recipe for gold/silver bars with impurities of zinc, iron, lead and copper. Can anyone point me in the right direction? Also looking for what each chemical does to drive the reaction. Using a furnace with a crucible and pouring bullion bars.

are you trying to refine by fluxing?

 

[alexxx]

Flux is a very broad term,
It is a substance used to make soldering easier by cleaning joint when soldering, or can be used to keep metals from oxidizing by high temperature's when welding or brazing.

...or we may use a little fluoride to act as an acid in melt, or we may add a metal in the melt to collect values like lead , litharge, or silver, we may also add a metal like iron to pick up sulfides from another metal.

Flux in my thinking, is a chemical we use to change the property of metals in the melt, basically a chemical reaction, or to improve melting environment to give us the desired results we seek.

Butcher,

Any idea on what flux needs to be added into a gas furnace for melting crt leaded glass to recover the lead inside the glass ?

cheers,
Alex

 

[butcher]

alexxx,
I am not really qualified to give a good answer here.
Why would anyone even want to try, unless they were a huge company with free fuel.
the heavy thick front glass on CRT, monitors, or TV this panel glass has almost no lead, but has around 10% barium oxide (BaO) to absorb Xray's, the thinner back part funnel glass can contain about 20% lead oxide PbO in the glass matrix, as lead glass.

I have heard they can make brick out of the glass in some country's to recycle the glass, but I am unsure if they separate the two types of glass and only use one type of the glass like the BaO or if they also make the brick out of the lead-glass portion also, since the lead in the glass is actually part of the glass itself as lead oxide, it would need a carbon source in the flux to reduce the lead back to metal, charcoal, flour, or something that would generate carbon, the carbon takes the oxygen from the PbO to form carbon dioxide gas in the melt, reducing lead back to metalic lead, also with this much lead oxide in the glass I expect the viscosity of the melt would need something like a little bit fluorite to make it more fluid so lead would settle from the slag glass when poured to a mold (this flux would be hard on crucibles tending to attack them also in the melt), and then of course the other basics to the flux recipe like borax and soda ash (sodium carbonate, washing soda), the glass already has an abundance of silica, then you would also need to have a lot of money to spend on fuel, in my opinion it would be worthless and dangerous to try this, unless you were a company who got paid to recycle the CRT, then you would be better of becoming a manufacture of CRT monitors and use them to make new CRT's or bricks out of them.

Messing with CRT's for the most part I see as a bad Idea, caution the are under a vacuum and can implode (explode inwards) if broken, there is a little tit of glass on the back portion where the pins electrical connections are, taking a pair of pliers, and breaking off this tit of glass will let the tube suck in air, and make it safe from implosion, if dropped or miss handled, also TV's or monitors can have large capacitors which can hold a dangerous charge, these should be shorted with a screw driver, and a jumper wire installed across capacitor terminals to keep the capacitor shorted (capacitors can regenerate a charge by sitting it is rare but it happens).

basically I would say forget this idea, and find a better Idea.

 

[g_axelsson]

Alexxx, if smelting the CRT glass for extraction of the lead could be done at a commercial level somebody would already be doing it and there wouldn't be a problem to get rid of our CRT:s.

Here is a report discussing recovery of CRT tubes (2004). http://www.environmental-expert.com/articles/materials-recovery-from-waste-cathode-ray-tubes-crts-3069

And a newer report (2013) that mentions that ordinary lead smelters accept the lead glass for usage in fluxes but needs payment to do so. It also states that some development is ongoing for small scale lead recovery.
http://www.calrecycle.ca.gov/Actions/Documents/77/20132013/835/Overview%20of%20CRT%20Issues%20and%20the%20CEW%20Program.pdf

Göran

 

[alexxx]

Thanks to Butcher & Goran for your kind replies.

Crt glass remains a day to day problem for small & large recyclers.
At this moment, I have to pay to get rid of some 6000 lbs weekly.
In my province, there's no government supported programs to monetize this hazardous material.
Glass to glass market is already flooded...
Lead smelters are charging more than the actual disposal cost + time needed to arrange transport...

Separating the panel from the leaded funnel glass is not a problem for me...
I'm really curious to experiment with some flux in order to recover some lead out of this glass.
If the challenge of recovering lead can be achieved, selling clean glass as an agregate would be easy...

I will try a few melts with various fluxes and will post results...

cheers,

Alex

 

[bswartzwelder]

It will be very interesting to see your results. I hope it works out well for you.