Making Ingots

[Matt-Aburg]

This thread continues my previous one on "press questions". I have a process for making briquettes down and also have other material to try. Briquette density is 68 % of solid. The compression ratio for fill is 7-1 over loose and is much easier to handle, and less air to oxidize. This is the next stage in my experiments on melting aluminum.

The first picture is of the raw 6061 chips to be pressed. I have an equal bin of other aluminum from tooling plate and mix.. Since it is mix, I might abandon it and just go onto the alloy wheels shown here to. I also have 3 large garbage bins of crushed cans for the lowest grade material. In the picture, you can see this small group were pre-burned to remove the paint and coating inside the cans.

 

[Dan Dubeau]

I'm curious enough that I'd be doing some experiments. Melting the same weight in solid form/loose chips/pressed chips and weighing the slag/yield. I have no doubt pressing the pucks will benefit somewhat, but the way aluminum oxidizes, it's already there on the chips, so I wouldn't expect miracles. Would be a fun experiment though, and helps to justify new shop equipment too.

 

[TorontoBuilder]

This thread continues my previous one on "press questions". I have a process for making briquettes down and also have other material to try. Briquette density is 68 % of solid. The compression ratio for fill is 7-1 over loose and is much easier to handle, and less air to oxidize. This is the next stage in my experiments on melting aluminum.

The first picture is of the raw 6061 chips to be pressed. I have an equal bin of other aluminum from tooling plate and mix.. Since it is mix, I might abandon it and just go onto the alloy wheels shown here to. I also have 3 large garbage bins of crushed cans for the lowest grade material. In the picture, you can see this small group were pre-burned to remove the paint and coating inside the cans.

I'm so jealous of your massive amount of chips.

I've been trying to shop for old wheel rims but the price expectations for even the worst quality rim is well above scrap value is it laughable.

 

[Matt-Aburg]

I'm curious enough that I'd be doing some experiments. Melting the same weight in solid form/loose chips/pressed chips and weighing the slag/yield. I have no doubt pressing the pucks will benefit somewhat, but the way aluminum oxidizes, it's already there on the chips, so I wouldn't expect miracles. Would be a fun experiment though, and helps to justify new shop equipment too.

Even if there is not much benefit in terms of oxidation, time saved from dumping less volume into the crucible will save gas. I will take you up on the comparison, once I get to melting.. There is also experiments to see what is the best flux too. See volume comparison.

 

[Janger]

Interesting Matt. A couple ideas - if while compressing the puck what if you pushed welding argon into the “mold” such that it replaces most of the oxygen. would it then give better results when melting? Less slag?

Could the chips be further reduced into sand or powder giving better melting results? I mean the pucks could have a higher density then?

Are the chips dirty in the sense they were produced with coolant all over them? Washing them might help prevent slag?

 

[jcdammeyer]

Also looking forward to the results.

 

[kevin.decelles]

I'm also watching this thread. I did some testing on the merits of melting some of @Janger 's chips and you've picked it up where I left off. My conclusion was that compression was required to eliminate air. I tried shielding in beer cans but that was fruitless.

 

[Matt-Aburg]

Interesting Matt. A couple ideas - if while compressing the puck what if you pushed welding argon into the “mold” such that it replaces most of the oxygen. would it then give better results when melting? Less slag?

Could the chips be further reduced into sand or powder giving better melting results? I mean the pucks could have a higher density then?

Are the chips dirty in the sense they were produced with coolant all over them? Washing them might help prevent slag?

The chips have mist spray coolant coating. I am wondering if preheat over the firepit will help to both remove moisture and burn off all oil. They seem dry, but this concerns me as to explosiveness. I have my new firepit ready now and could bbq them for a while..

 

[Susquatch]

I'm watching too. I have a large collection of aluminium chips I'd love to turn into machinable blocks.

My thoughts on the matter are mostly pessimistic.

Smaller chips have more surface area to oxidize.

Coolant might be a good thing if it reduces long term oxidation.

Preheating in air would probably increase oxidation.

Interesting idea to add argon.

For now, it's just easier for me to buy aluminium stock.

I'm planning a visit to a recycler in the near future. I might ask them how they handle this problem.

 

[Tom O]

Try covering the crucible and put some wood in it to use up the oxygen
I have seen Windyhills foundry using silica sand on his iron pours.

 

[pdentrem]

A reasonably sealed cover and wood or charcoal/carbon would help immensely.
At work certain metals are oxygen grabbers. Copper, silver, lead, aluminum and tin. Copper looks like Swiss cheese at times, Silver IS Swiss cheese! Aluminum and tin make chalk like oxides. Palladium is normally done in a vacuum furnace, though if alloyed with gold, a CO fueled torch head (see photo, no oxygen required) will allow you to make a solid bar. As long as the torch keeps the metal covered until the color drops below red. We use this torch head when using an open crucible. In the sealed continuous casting machine, nitrogen is used as it is much cheaper than argon.

 

[Janger]

a CO fueled torch head (see photo, no oxygen required) will allow you to make a solid bar. As long as the torch keeps the metal covered until the color drops below red. We use this torch head when using an open crucible. In the sealed continuous casting machine, nitrogen is used as it is much cheaper than argon.

I like it when we hear from somebody who does that at work. Thanks @pdentrem . I've never heard of a carbon monoxide fueled torch. Got any pictures of this in operation? And what is a sealed continuous casting machine? more pictures?

 

[pdentrem]

The casting machine is similar to an extruder but it actually pulls on the metal. The Argon or nitrogen gas is the cover gas to prevent oxygen from contaminating the melt and prevents the carbon crucibles and casting dies inside from burning.
As for the CO fueled torch, it is just a regular Harris oxy/fuel torch head but no oxygen tank connected. Think of a rosebud torch head but much wider, softer flame. Like a weed or kennel burner. What we are doing to place the torch head above the open crucible so that the flame fills the space, thus any oxygen is consumed by the CO and it also can breakdown oxides that float to the top of the melt. We work with +99.99% pure metals as the specifications in the aviation/tech industries as quite tighter than what most people would need.

Here are photos from the maker of the machine.

Photo Gallery | Continuous Casting | Rautomead

Here is a selection of images from our Continuous Casting Metals Gallery at Rautomead. Look how Rautomead work process happens in a set of images.

www.rautomead.com

 

[Janger]

@pdentrem one point to clarify - CO torch? Is the fuel CO or is that the output from the flame from burning something else? I thought CO, CO2, H2O, were all products of the reaction of burning a fuel. ie. CO does not burn it's already burnt. ? What does your company make with those different metals in aviation/tech?

 

[Ironman]

A flux is often used to shield the melt from Oxygen and also collects impurities.
Borax, a bit of calcium flouride, an bit of all purpose flour,
3 parts Borax
1 part Sodium Carbonate
1 part silica
1 part Fluorospar
flour as needed for oxide burn off

 

[pdentrem]

CO is the fuel. It does burn. It becomes CO2.

hi-rel.com has some stuff there.

 

[jcdammeyer]

A flux is often used to shield the melt from Oxygen and also collects impurities.

What and where to buy? Have I got it right?

Borax, a bit of calcium flouride, an bit of all purpose flour,
3 parts Borax

Amazon.ca

1 part Sodium Carbonate

https://www.amazon.ca/Arm-Hammer-Super-Washing-Soda/dp/B0029XNTEU/ref=sr_1_5

1 part silica

Fumed Silica C-THIX 100 by CECCORP (1 Quart / 946 mL) – Extremely Fine, Amorphous White Powder with Very High Purity - Walmart.ca

Buy Fumed Silica C-THIX 100 by CECCORP (1 Quart / 946 mL) – Extremely Fine, Amorphous White Powder with Very High Purity from Walmart Canada. Shop for more Interior Wood Stains & Finishes available online at Walmart.ca

www.walmart.ca

1 part Fluorospar

Fluorspar 50 Pounds

A crystalline mineral that has a lower fluxing temperature than other calcium compounds. Also used to promote more fusible glazes. 50 lbs. $.90 per pound For larger quantities, click here for a quote.

evansceramics.com

flour as needed for oxide burn off

Are there cheaper suppliers for Florospar that does require 50 lbs?

 

[Ironman]

Florospar is used to make the melt and flux more liquid, as silica makes it gooey. Yes, there has to be a better source as 50lb is huge.

 

[Matt-Aburg]

A flux is often used to shield the melt from Oxygen and also collects impurities.
Borax, a bit of calcium flouride, an bit of all purpose flour,
3 parts Borax
1 part Sodium Carbonate
1 part silica
1 part Fluorospar
flour as needed for oxide burn off

Is this for Aluminum melting ?

 

[pdentrem]

I like it when we hear from somebody who does that at work. Thanks @pdentrem . I've never heard of a carbon monoxide fueled torch. Got any pictures of this in operation? And what is a sealed continuous casting machine? more pictures?

This is a “F” crucible with a small melt. Induction furnace at 30000 watts. Here the torch is covering the melt. It is off to the side a bit, as operator is preparing to use a carbon rod seen on the left side already red hot, as he moved it away to clarify what you are seeing, to cool the metal prior to pouring into a mound.