Sulphur vs Nitrates vs Oxygen degassing to oxidize base metals

[Ayham Hafez]

After long time of experiments, I admitted that the only way to oxidize base metals is by purging oxygen into molten E-waste alloy.

Friends of mine which has a very good channel on YouTube talking about precious metals recovering and showing many different ways, has did a very great video showing the differences between three mentioned methods, the most important thing that make me confused about using oxygen degassing method is that I read in the forum that it took hours to oxidize the base metals but didn't see any information about how much base metals weight to be oxidized in those hours, when I discussed with the video maker, he mentioned that 1 minute oxidized about 70 grams of base metals that mean 1 hour can oxidize more than 4 kg of base metals.

Here is the link of the video.



By the way, before he started recovering the gold from those ic chips, he did a wet ashing test and got a yield of 50.8 grams per ton, I was following up with him, and now he got almost the full yield.

 

[4metals]

The oxygen sparging is the most efficient because you constantly renew the oxygen in the molten pool. He was using a small crucible and I can believe he reacted it completely rather quickly. I have always sparged much larger melts which took longer. I also cut the oxygen flow down to the point where very little gas broke the surface of the melt, assuring efficient consumption. I also notice he used a stainless pipe to gas the melt. Surely they have stainless pipe in Lybia!

 

[Shark]

The oxygen sparging is the most efficient because you constantly renew the oxygen in the molten pool. He was using a small crucible and I can believe he reacted it completely rather quickly. I have always sparged much larger melts which took longer. I also cut the oxygen flow down to the point where very little gas broke the surface of the melt, assuring efficient consumption. I also notice he used a stainless pipe to gas the melt. Surely they have stainless pipe in Lybia!

Will stainless take that much heat? That is interesting if it will.

 

[4metals]

I. never tried it but I was able to get refractory tubes and quartz glass tuber here in the USA. The guy in the video used stainless, or so he said!

Google's AI said this;
Stainless steel has a melting point range of 2,550–2,790°F (1,400–1,530°C), which is higher than the melting points of aluminum and copper. The exact melting point depends on the alloy's chemical composition, specifically the proportions of iron, chromium, nickel, and other elements. For example, 316 stainless steel, which contains molybdenum to improve corrosion resistance, melts at 2,500–2,550°F (1,375–1,400°C). Here are the melting points for some other common grades of stainless steel:

• Grade 304: 2,552–2,642°F (1,400–1,450°C)
• Grade 430: 2,597–2,750°F (1,425–1,510°C)
• Grade 434: 2,600–2,750°F (1,426–1,510°C

So the temperature rating seems OK

 

[Shark]

That is a surprise. I have never needed to look into it but would have guessed stainless would have melted easier than that.

 

[Ayham Hafez]

I. never tried it but I was able to get refractory tubes and quartz glass tuber here in the USA. The guy in the video used stainless, or so he said!

Google's AI said this;
Stainless steel has a melting point range of 2,550–2,790°F (1,400–1,530°C), which is higher than the melting points of aluminum and copper. The exact melting point depends on the alloy's chemical composition, specifically the proportions of iron, chromium, nickel, and other elements. For example, 316 stainless steel, which contains molybdenum to improve corrosion resistance, melts at 2,500–2,550°F (1,375–1,400°C). Here are the melting points for some other common grades of stainless steel:

• Grade 304: 2,552–2,642°F (1,400–1,450°C)
• Grade 430: 2,597–2,750°F (1,425–1,510°C)
• Grade 434: 2,600–2,750°F (1,426–1,510°C

So the temperature rating seems OK

No, he used ceramic tube not stainless steel (Used for winding electric furnace elements) , only in Aluminum nitrogen degassing they use stainless steel cause they purging nitrogen at 800 c temp

Editing:

At 10:56 he clearly mentioned that its ceramic tube.

 

[Shark]

No, he used ceramic tube not stainless steel (Used for winding electric furnace elements) , only in Aluminum nitrogen degassing they use stainless steel cause they purging nitrogen at 800 c temp

Editing:

At 10:56 he clearly mentioned that its ceramic tube.

There you go. Another place you may be able to find a useful item.

 

[Shark]

Not sure this will help but I found this website.

https://arabic.muffle-furnace.com/s...-tube-1600-high-temperature-ceramic-tube.html

 

[orvi]

No, he used ceramic tube not stainless steel (Used for winding electric furnace elements) , only in Aluminum nitrogen degassing they use stainless steel cause they purging nitrogen at 800 c temp

Editing:

At 10:56 he clearly mentioned that its ceramic tube.

UV-C germicidal lamps have quartz glass tube - as 254 nm won´t penetrate regular glass. This is fairly decently priced quartz tube for blowing. Also, halogen lamps are made from quartz glass. These are often sturdier and cheaper than UV-C "fluorescent tubes".

You can maybe use also these, but there will be limitations, mainly with length. Also, flux will eat them very quickly.

Another material nicely resistant to oxygen and fairly high temperatures is silicon carbide. DPF filters often have honeycombs made from SiC material. On the other hand, cordierite (ceramic) ones are also fairly resistant. Just cut the appropriate horizontal piece all the way and also cut the end where combs are pluged. DPF honeycombs are a nice thing for example for pre-heating air or oxygen influx to the furnances - like DIY heat-exchangers.

These alumina ceramic tubes which he shows are nice, but usually prone to temperature shock and thus cracking.

 

[Ayham Hafez]

UV-C germicidal lamps have quartz glass tube - as 254 nm won´t penetrate regular glass. This is fairly decently priced quartz tube for blowing. Also, halogen lamps are made from quartz glass. These are often sturdier and cheaper than UV-C "fluorescent tubes".

You can maybe use also these, but there will be limitations, mainly with length. Also, flux will eat them very quickly.

Another material nicely resistant to oxygen and fairly high temperatures is silicon carbide. DPF filters often have honeycombs made from SiC material. On the other hand, cordierite (ceramic) ones are also fairly resistant. Just cut the appropriate horizontal piece all the way and also cut the end where combs are pluged. DPF honeycombs are a nice thing for example for pre-heating air or oxygen influx to the furnances - like DIY heat-exchangers.

These alumina ceramic tubes which he shows are nice, but usually prone to temperature shock and thus cracking.

Thanks for valuable information, do you have photos for DPF filter after been modified to be as degassing tube? Cause I didn't understand how to make it

 

[4metals]

He just uses a tube, which he does say is ceramic. He somehow blocks the gas from coming out the top, probably with a silicone stopper, and uses his oxy acetylene torch but only turns on the oxygen. The end of the tube where the gas is injected does not get too hot.

 

[Ayham Hafez]

He just uses a tube, which he does say is ceramic. He somehow blocks the gas from coming out the top, probably with a silicone stopper, and uses his oxy acetylene torch but only turns on the oxygen. The end of the tube where the gas is injected does not get too hot.

He said to me that he used high oxygen pressure to make oxygen go throw the molten surface, but I can't imagine that I will stand infront of the furnace more than hour catching the acetylene torch, I'm trying to find a way that prevent oxygen from go out the tube and in same time I will not catch anything cause am willing to make degassing for at least 10 kg alloy each time.

BTW, is his approach ok of adding flux after finishing degassing? Or its better to add fluxes before start degassing?

 

[4metals]

I always added fluxes first. Once you settle on a tube to use for gassing you can set it up with an oxygen cylinder and tubing and not have to stand over the furnace once it is set up.

 

[Ayham Hafez]

I always added fluxes first. Once you settle on a tube to use for gassing you can set it up with an oxygen cylinder and tubing and not have to stand over the furnace once it is set up.

Hope I can get a ceramic or silicon carbide pipe with thread, so I can easily attach the oxygen cylinder without loosing oxygen out from the top of the pipe.

 

[Shark]

Hope I can get a ceramic or silicon carbide pipe with thread, so I can easily attach the oxygen cylinder without loosing oxygen out from the top of the pipe.

You can use a high temperature sealant such as used for stoves. It is usually rated around 1200-1250 degrees and should hold up to seal the supply end. Most are made of a proprietary silicone base and molds really well. Also you can get high temp rope used to seal the doors on wood heaters, and some larger furnaces. Might take some searching where your at, but I would think someone would atleast have the sealant on hand.

 

[Ayham Hafez]

You can use a high temperature sealant such as used for stoves. It is usually rated around 1200-1250 degrees and should hold up to seal the supply end. Most are made of a proprietary silicone base and molds really well. Also you can get high temp rope used to seal the doors on wood heaters, and some larger furnaces. Might take some searching where your at, but I would think someone would atleast have the sealant on hand.

That's a good idea, many thanks, will start to search.

 

[orvi]

Hope I can get a ceramic or silicon carbide pipe with thread, so I can easily attach the oxygen cylinder without loosing oxygen out from the top of the pipe.

With long enough tube, you can fit it directly onto delivery hose. I never solved such issue since we always used oxygen concentrator as source of oxygen, not the oxygen pressure tank. This was much handier, not refills, low pressure and decent flow.

 

[Ayham Hafez]

With long enough tube, you can fit it directly onto delivery hose. I never solved such issue since we always used oxygen concentrator as source of oxygen, not the oxygen pressure tank. This was much handier, not refills, low pressure and decent flow.

Oxygen concentrator has a very low pressure, is it very easy to oxygen to push the molten with this low pressure and reach to the bottom of the crucible? Do you make oxygen purging with fluxes or you add fluxes at the end after finished oxygen purging to make metals oxides into flux?

 

[orvi]

Oxygen concentrator has a very low pressure, is it very easy to oxygen to push the molten with this low pressure and reach to the bottom of the crucible? Do you make oxygen purging with fluxes or you add fluxes at the end after finished oxygen purging to make metals oxides into flux?

You do not need to submerge the tube very deep/all the way. Just keeping it little bit below the level of the metal (below flux/slag) is OK - if you are doing it this way. We usually skimmed the viscous oxide slag forming and blew oxygen onto the surface - saving the tubing from attack of the slag as we used quartz.

 

[Ayham Hafez]

You do not need to submerge the tube very deep/all the way. Just keeping it little bit below the level of the metal (below flux/slag) is OK - if you are doing it this way. We usually skimmed the viscous oxide slag forming and blew oxygen onto the surface - saving the tubing from attack of the slag as we used quartz.

With fluxes its very hard to skim the oxides or at least I don't know how, cause oxidized metals absorbed by fluxes and be very thin and similar to molten (very liquid)

If we have 1 kg alloy that has 50% Copper, so we need to oxidize half kilo of base metals, with very low oxygen source, how long time we need to oxidize the half kilo of base metals (approximately)


Second question, is it better to make oxygen degassing with fluxes or add fluxes after we finish oxygen degassing?