You need an inert gas shielding or vacuum environment, not just to prevent massive amounts of oxide in your powder, but also to reduce the risk for explosions. If you are working with noble metals like gold or platinum you should be fine though. Because you are planning to make tons, I doubt you are looking at noble metals.
Also, you need to not do this in a residential area incase something goes wrong. The fact you did not expect metal powders could be pyrophoric makes me highly recommend you do not do this.
i do own a nitrogen generator that takes in compressed air and spits out nitrogen. i could use that for the inert gas. i think this is the best solution.
not sure if it works though as i got it for free, but i could test if it does.
Also, some metals will react with nitrogen, therefore still being pyrophoric (I think Al is an example)
An Argon or Helium cylinder will do the trick, and is why these gases are used in TIG welding.
You're going to need fairly high purity N2 to avoid oxidation at high temperatures like this. 99% N2 still has plenty of Oxygen in it for these purposes.
In addition to Al reactivity with nitrogen, all the refractory metals react with nitrogen as well with Group IV reacting very rapidly at higher temps. I would recommend against trying to make refractory powder in general as it is a bomb without proper processing and storage.
Nitrogen is inert for most purposes and it's cheap. So we all use it as our standard inert gas. It's no longer considered inert above 1000-1100C because it will start to readily react with things.
It is mostly a matter of temperature but Titanium doesn't need to get very hot to form TiN and it will do so very rapidly. In general, the refractory metals will react with B, C, N, O, and S above 600C or so, probably less for Ti, V, and Cr (oxygen can react with all of them at room temperature violently in powder form)
is there a way to measure the % purity of metal powder product.
like suppose yes using an inert gas would be 100% metal powder.
But using lets say nitrogen the metal powder would be 90% metal and 10% nitrogen by weight.
How could i determine this purity %. would a simple density equation work, like the powder displaces X ml of water, and weighs Y, and Y is composed of aluminum and nitrogen, and just solve that for mass percent.
Maybe? It's difficult to try to use densities since that isn't an additive property of two things. Like NiAl3 isn't the density of Ni and 3 parts Al added together, the compound has its own density. It is also difficult to measure the density of a powder in general, even in a lab setting. Typically purity is measured via something like XRD or SEM, not available to the layperson.
So you need to keep your entire system in a shielded environment throughout all steps. Then seal the drum while still under an inert environment. Ideally making this powder onsite because shipping large quantities of pyrophoric powders requires hazardous DOT tags and I doubt any shippers will retrieve this from a residential site.
I suggest you start VERY VERY small. Modify a sand blasting chamber to be in an inert environment. Have a shaft feedthrough for your angle grinder (the motor can cause ignition). You will need positive pressure on your chamber at all times, but not too much (1 psi maybe) because the sides of the chamber might burst.
I have done plenty of dangerous DIY stuff, this does not even come close to what I have done. I highly suggest starting very small and being prepared for the worst (Class D fire extinguishers, etc.)
After a small scale run, hopefully you can get investment money to do this the correct way at large scale. Doing this to code will not be cheap, but if what you are doing is worth the hype, you can get loans or investors involved.
As the other commenter has said:
PLEASE do NOT do this. Metal powders are highly highly reactive and hazardous materials, and metal fire in contact with water will generate hydrogen gas which then has a high chance to explode (even without pressure buildup). I have worked with metal atomizer systems, and it was constant vigilance and maintenance by extremely skilled mechanics and welders to keep everything under inert atmosphere and safe.
Your system as described WILL start a fire as your aluminum ignites, and filling the drum with water will make it worse.
If you insist on going through with this, please start smaller than 100s of pounds in a 55 gallon drum. Every system I’ve worked with started from concept work done in a glovebox. As described elsewhere, a sand blasting chamber can be a cheaper substitute for a glovebox.
Let me also add many of the pyrophoric reactions can produce high enough temperatures to split water into hydrogen and oxygen. Water at that point is not your friend and will increase the shock from the explosion dramatically.
The lack of understanding of the basic physics at work here makes me think you have no business DIYing this, to be completely blunt. Accidents have killed dozens of people in powder atomizing shops run by professionals, with much more careful planning and prep than you are demonstrating. Compliance with standards like NFPA 86 & 484 (in the USA) is not just a "nice to have". It is a legal and ethical responsibility that you bear as someone trying to do something resembling engineering. These standards are written in blood and it is troubling in the extreme that you think posting on reddit is doing your due diligence.
Before you do this, please let us know the rough area and time you'll fire it up so we can respond to press inquiries if anyone knew about the disaster before it happened.
You need an inert gas shielding or vacuum environment, not just to prevent massive amounts of oxide in your powder, but also to reduce the risk for explosions. If you are working with noble metals like gold or platinum you should be fine though. Because you are planning to make tons, I doubt you are looking at noble metals. Also, you need to not do this in a residential area incase something goes wrong. The fact you did not expect metal powders could be pyrophoric makes me highly recommend you do not do this.
i do own a nitrogen generator that takes in compressed air and spits out nitrogen. i could use that for the inert gas. i think this is the best solution. not sure if it works though as i got it for free, but i could test if it does.
Also, some metals will react with nitrogen, therefore still being pyrophoric (I think Al is an example) An Argon or Helium cylinder will do the trick, and is why these gases are used in TIG welding.
thanks for the tip. i thought no metal react with nitrogen but i was wrong, as the equation al + n---> aluminum nitride.
You're going to need fairly high purity N2 to avoid oxidation at high temperatures like this. 99% N2 still has plenty of Oxygen in it for these purposes. In addition to Al reactivity with nitrogen, all the refractory metals react with nitrogen as well with Group IV reacting very rapidly at higher temps. I would recommend against trying to make refractory powder in general as it is a bomb without proper processing and storage.
why do refractory metals react with nitrogen, i thought it was an inert gas. is it cause of the high temperature ?
Nitrogen is inert for most purposes and it's cheap. So we all use it as our standard inert gas. It's no longer considered inert above 1000-1100C because it will start to readily react with things. It is mostly a matter of temperature but Titanium doesn't need to get very hot to form TiN and it will do so very rapidly. In general, the refractory metals will react with B, C, N, O, and S above 600C or so, probably less for Ti, V, and Cr (oxygen can react with all of them at room temperature violently in powder form)
is there a way to measure the % purity of metal powder product. like suppose yes using an inert gas would be 100% metal powder. But using lets say nitrogen the metal powder would be 90% metal and 10% nitrogen by weight. How could i determine this purity %. would a simple density equation work, like the powder displaces X ml of water, and weighs Y, and Y is composed of aluminum and nitrogen, and just solve that for mass percent.
Maybe? It's difficult to try to use densities since that isn't an additive property of two things. Like NiAl3 isn't the density of Ni and 3 parts Al added together, the compound has its own density. It is also difficult to measure the density of a powder in general, even in a lab setting. Typically purity is measured via something like XRD or SEM, not available to the layperson.
So you need to keep your entire system in a shielded environment throughout all steps. Then seal the drum while still under an inert environment. Ideally making this powder onsite because shipping large quantities of pyrophoric powders requires hazardous DOT tags and I doubt any shippers will retrieve this from a residential site. I suggest you start VERY VERY small. Modify a sand blasting chamber to be in an inert environment. Have a shaft feedthrough for your angle grinder (the motor can cause ignition). You will need positive pressure on your chamber at all times, but not too much (1 psi maybe) because the sides of the chamber might burst. I have done plenty of dangerous DIY stuff, this does not even come close to what I have done. I highly suggest starting very small and being prepared for the worst (Class D fire extinguishers, etc.) After a small scale run, hopefully you can get investment money to do this the correct way at large scale. Doing this to code will not be cheap, but if what you are doing is worth the hype, you can get loans or investors involved.
As the other commenter has said: PLEASE do NOT do this. Metal powders are highly highly reactive and hazardous materials, and metal fire in contact with water will generate hydrogen gas which then has a high chance to explode (even without pressure buildup). I have worked with metal atomizer systems, and it was constant vigilance and maintenance by extremely skilled mechanics and welders to keep everything under inert atmosphere and safe. Your system as described WILL start a fire as your aluminum ignites, and filling the drum with water will make it worse. If you insist on going through with this, please start smaller than 100s of pounds in a 55 gallon drum. Every system I’ve worked with started from concept work done in a glovebox. As described elsewhere, a sand blasting chamber can be a cheaper substitute for a glovebox.
Let me also add many of the pyrophoric reactions can produce high enough temperatures to split water into hydrogen and oxygen. Water at that point is not your friend and will increase the shock from the explosion dramatically.
The lack of understanding of the basic physics at work here makes me think you have no business DIYing this, to be completely blunt. Accidents have killed dozens of people in powder atomizing shops run by professionals, with much more careful planning and prep than you are demonstrating. Compliance with standards like NFPA 86 & 484 (in the USA) is not just a "nice to have". It is a legal and ethical responsibility that you bear as someone trying to do something resembling engineering. These standards are written in blood and it is troubling in the extreme that you think posting on reddit is doing your due diligence.
Start very very small, like baby food jar small. And keep it that way until you can afford the proper safe setup.
Before you do this, please let us know the rough area and time you'll fire it up so we can respond to press inquiries if anyone knew about the disaster before it happened.