Ayham Hafez
Well-known member
Asked about it, none knows anything about quartz tubing, this is the curse of non-industrial countries.
E-waste copper-lead alloy cupellation
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We have to assume no one knows the rules in Lybia as well as you do. All we can do is tell you what the rest of the world uses. If you cannot import you may be out of luck. Do you have glass blowers in Lybia, googling quartz glass suppliers Lybia brings up desert glass and types of art glass. maybe they can get quartz glass?
Ayham Hafez
Well-known member
No glass blowers here, but I asked someone work in glass industry in Egypt but he didn't know about quartz glass that can carry out very high temperature without be melted.
Have a question, how we can control the oxidizing of base metals without oxidize copper? I mean how knows when stop degassing during smelting? From my cupellation tests I noticed that copper oxidized very quickly once air hit its surface.
Selective oxidation? Hmmmmm above my pay grade.
Ayham Hafez
Well-known member
I think the available way is just to estimate how much copper is in the e-waste molten, then during degassing skim off the oxides and see how much molted metal still in the crucible, isn't it?
Now I use this method to estimate if I finished oxidizing lead during cupollation or not, sine I cupel with copper and very little amount of PM's.
Ayham Hafez
Well-known member
Can we use potassium nitrates after smelting? I mean after we smelt E-waste and get mixed alloy, I assume that we can remelt it without fluxes, then after been melted, add some potassium nitrate with some borax for example 25% from the weight of the alloy, then base metals should be oxidized, stir the molten then skim off the oxides, then make shots or anodes, what do you think?
Generally O2 sparging takes a long time in the molten pool for completion. Using nitrates in the flux will oxidize metals but it doesn't last long and it (all fluxes) floats. Sparging with gaseous O2 supplies the gas to the bottom of the melt so the O2 rises through the melt reacting as it rises. Gas is just much more effective.
Ayham Hafez
Well-known member
Yes I believe that oxygen sparging is the best, but since its not available for me, is it good to test add nitrates to molten alloy or it will not work
It is a gamble whether or not it will work, I have my doubts. But you have limited options.
Ayham Hafez
Well-known member
I tested potassium nitrate with e-waste alloy couple times, almost I got same alloy weight each time, even iron and tin not oxidized, I started to add 10% KNO3 from alloy weight and reach up to 50% with no changes, no metals oxidized, I make sure about using oxidizing flame all the time, and stir the KNO3 mixed with borax and soda ash to absorb the oxides, I tested the KNO3 activity by using it with HCL and H2SO4 to form AR,and it's work well.
Now I have no choice rather than sparging oxygen into molten alloy, till I can get the sparging tube I have couple questions.
In smelting thread, you shared a table about metals contents in E-waste, Copper almost 50% by weight of e-waste metals, so let's say we have 1 kg e-waste alloy that approximately has 0.5 kg of base metals that we want to oxidize, how long time we need to make sparging pure oxygen into the molten (very low oxygen volume to avoid molten bubbling), I know it's hard to know the exact time but I need an estimation based on your experience, in Smelting thread you mentioned 6 to 8 hours but I think you were talking about degassing into crucible no 150, so I don't know how much metals inside it.
Friend of mine told me that when there is iron, while oxygen degassing there will be a lot of sparks, so we know that iron fully oxidized when sparks stops, any other indicator from your experience that oxidization done for base metals?
I already have a furnace built with refractory material, it has no crucible, it helps me with reducing the crucible cost, so I smelt E-waste with it to make E-waste alloys, then I will use small foundry furnace with small crucible maybe no 25 to melt 10 Kg of E-waste alloys (from 50 kg PCB's components without circuit boards) after alloys been melted I will add some borax, silica and soda ash then start sparging oxygen, if I missed anything kindly tell me.
This sounds like a good approach, I was able to remove a lot of the magnetics before smelting and this saved on the need to remove the iron, which does spark, I did my smelting in the days of Atomic Absorption rather than XRF analysis so a sample was taken after a few hours and run on the Atomic Absorption to see where we stood. Our experience was longer gassing periods to get the copper purity up. Today an XRF simplifies the process but the flux layer prevented any visuals on the molten metal so I always went by analysis and never color of the metal in the crucible. I will say you will have better results by using a crucible full enough to allow the gas to bubble through more of the molten pool so determine the weight of your feed by how full you can safely fill your crucible.
Chris Owen, GSP, a former moderator here used air to sparge, and he didn't have to be concerned with conserving bottled gas so he allowed the reaction to bubble at a safe no splash rate.
Ayham Hafez
Well-known member
Sounds good, I have experience with refining lead, we were use spectrometer for analysis samples while lead melted, so each hour we took sample till we reach to the required purity, but with lead it's easy to take sample since there is no flux layer, but with my small business at least right now it's not an option to buy an xrf analyser to use it in this stage
I think using compressed air will increase the degassing period 4 or 5 times cause air only has 21% oxygen, so un-required gas will go throw the molten while we use pure oxygen instead, also air has 78% nitrogen which usually Aluminum refiners use it for degassing Aluminum so they make sure they remove all oxygen from the molten aluminum, I don't know haw nitrogen will effect E-waste alloy melting, but I think nitrogen react much faster with oxygen thermally than metals.
How ever, just one figure or estimation about how long time will took to finish sparging 1 kg of E-waste alloy with pure oxygen will help me to make a start on my experiment.
