Sulphur vs Nitrates vs Oxygen degassing to oxidize base metals

[Lou]

My experience "piping" materials was in the context of a rotary furnace. There is no hard set rule on copper and base metals but generally the big enemy is iron. You want the shot to be nonmagnetic. I've tried over the years quartz (expensive but resistant to oxygen and works well if IN the melt and not exposed to corrosive metal oxides, in particular CuO!), alumina (breaks very easily) but the only thing I've ever seen hold up is preheated zirconia blowers like what they use for steel.

I've done with sterling and with copper and it was always blown after the borax or flux was added. The flux is the receiver for the oxides so if it's not there you can't blow oxygen. If the melt is high in iron you will actually generate some heat in the melt pool if doing this in a rotary. At one place I rep material at, it's usually 3000-4000 lbs Cu, half as much borax, roll it around 3-4 hours then check if some of the material is magnetic from iron. Zinc is already out at that point. Then 1" diameter schedule 40 iron pipe and oxygen...

 

[Ayham Hafez]

My experience "piping" materials was in the context of a rotary furnace. There is no hard set rule on copper and base metals but generally the big enemy is iron. You want the shot to be nonmagnetic. I've tried over the years quartz (expensive but resistant to oxygen and works well if IN the melt and not exposed to corrosive metal oxides, in particular CuO!), alumina (breaks very easily) but the only thing I've ever seen hold up is preheated zirconia blowers like what they use for steel.

I've done with sterling and with copper and it was always blown after the borax or flux was added. The flux is the receiver for the oxides so if it's not there you can't blow oxygen. If the melt is high in iron you will actually generate some heat in the melt pool if doing this in a rotary. At one place I rep material at, it's usually 3000-4000 lbs Cu, half as much borax, roll it around 3-4 hours then check if some of the material is magnetic from iron. Zinc is already out at that point. Then 1" diameter schedule 40 iron pipe and oxygen...

Thanks for valuable information.

"Then 1" diameter schedule 40 iron pipe and oxygen..."

Could you explain this point.

 

[orvi]

Thanks for valuable information.

"Then 1" diameter schedule 40 iron pipe and oxygen..."

Could you explain this point.

https://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html

It refers to the dimensions and ID/OD of the pipe.

 

[Ayham Hafez]

https://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html

It refers to the dimensions and ID/OD of the pipe.

Sorry but now I'm more confused, maybe I didn't understand your English.

You mentioned that you used zirconia tube which as I understand made from ceramic and some other materials, then you talked about iron tube coated with zinc.


Do you mean we can use galvanized steel tube in purging oxygen into molten???

 

[Yggdrasil]

Sorry but now I'm more confused, maybe I didn't understand your English.

You mentioned that you used zirconia tube which as I understand made from ceramic and some other materials, then you talked about iron tube coated with zinc.


Do you mean we can use galvanized steel tube in purging oxygen into molten???

Just a description of the dimensions, not the material.

 

[Ayham Hafez]

Just a description of the dimensions, not the material.

Thanks for help, that makes sense.

 

[Ayham Hafez]

My experience "piping" materials was in the context of a rotary furnace. There is no hard set rule on copper and base metals but generally the big enemy is iron. You want the shot to be nonmagnetic. I've tried over the years quartz (expensive but resistant to oxygen and works well if IN the melt and not exposed to corrosive metal oxides, in particular CuO!), alumina (breaks very easily) but the only thing I've ever seen hold up is preheated zirconia blowers like what they use for steel.

I've done with sterling and with copper and it was always blown after the borax or flux was added. The flux is the receiver for the oxides so if it's not there you can't blow oxygen. If the melt is high in iron you will actually generate some heat in the melt pool if doing this in a rotary. At one place I rep material at, it's usually 3000-4000 lbs Cu, half as much borax, roll it around 3-4 hours then check if some of the material is magnetic from iron. Zinc is already out at that point. Then 1" diameter schedule 40 iron pipe and oxygen...

I made a research in the market and noticed that many Chinese companies specialized in refractory ceramic products such as zirconia, Sic, alumina etc... only recommend Si3N4 combined with SiC tubes, they highly recommend pure Si3N4 tubes but their price for 1 inch 700 mm length tubes is above 300 USD per piece so they advised for Si3N4 combined with SiC for about 50 USD per piece, they didn't recommend Zirconia because of highly oxidization environment.


They mentioned that Si3N4-SiC tube can stand for about 3 months of use, do you have any experience with it? I'm trying to find the proper solution for the degassing tube with less cost, your advice is highly appreciated.