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Please check out this explanation of the Ellingham Diagram from MIT.  

 

One thing I neglected to mention is that the Ellingham-Richards chart is all very dependent on exposure to free oxygen.  Inside a solid mass of metal you still rely on diffusion for things to move, then at the surface you have the opportunity for these reactions.  A liquid state allows much faster movement of elements to get to the surface.  From there you have to have free oxygen to reach the metal.  With induction melting we can keep this from happening with the SPAL process, where we drip liquid argon onto the liquid bath.  The argon expands greatly and displaces all oxygen, therefore no oxides!  The bigger reason this is often done is to keep the nitrogen out.  

 

Borax is sodium tetraborate decahydrate, Na2B4O7*10H2O, with the Na2B4O7 being the important bit.  Apply the principles of the chart above to the Na and B in borax and you will see that both like oxygen more than iron; or at least you would if they were on that chart.  But their reaction is definitely below iron, so they will preferentially strip the oxygen from iron oxide if the conditions are right (temperature and partial pressures).  This would also be true for lines above the iron line, but not necessarily any below the iron line, and keep in mind that the lines aren't all parallels to each other, so different things will be preferential in different conditions.  

 

BTW, there are also diagrams for things besides oxides, like sulfides.  Neat stuff.  

 

Carbon boils happen at a variety of temperatures, depending on the chemistry of the bath.  It generally happens when there is too much rust (iron oxide, and note that different forms of iron oxide have different lines on the chart) in the base charge so the reaction starts.  We stop the reaction by throwing a little ferrosilicon or aluminum in the bath to preferentially react with the oxygen.  No oxygen in the bath means the carbon isn't able to convert to CO.  

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That's just too cool, Jerrod!  Thanks for the explanation.  I'm stuck in the 19th century, science-wise, when it comes to smelting/remelting.  

 

And "Liquid Argon Drip" would be a great name for metal band...

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5 hours ago, Alan Longmire said:

And "Liquid Argon Drip" would be a great name for metal band...

Second that!:lol:

 

OK so no borax! Maybe that's what I was actually watching - not steel turning liquid but all the slag and extra borax leaking out. Still was really cool to see. Just wish I could have videoed it.

6 hours ago, Jerrod Miller said:

BTW, there are also diagrams for things besides oxides, like sulfides.  Neat stuff. 

VERY neat stuff. Again, second Alan's comment "That's just too cool".

I was wondering where Na and B fell on the graph. Do they fall above or below Cr?

 

This is a serious rabbit hole that I'm going to have to go down - but not tonight. Been up for 17 hours on 4 hours of sleep.

 

Thanks to you both for all the information.

 

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Na is way low on the graph, should be lower than Ca; very reactive stuff.  B looks to be just below and parallel to Mn.  Keep in mind though we aren't interested in just Na and B.  We have to consider a reaction/state that is lower energy than Na2B4O7.  So it is not going to be 4/3B+O2 = 2/3B2O3, We are going to be looking at something like Na2B4O7 + 1/2O2 = 2NaO + 2B2O3, or something along those lines, not too familiar with boron oxides.  At any rate that would be a completely different line.  It could even break down into something else that is some version of NaxByOz before dropping again to separate Na and B oxides.  And the difference between those energy states may mean that there is now something else in between.  

Ellingham diagram for oxides. | Download Scientific Diagram

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As the late Larry Harley once said to the late Al Pendray during a crucible smelt (direct reduction of ore in a sealed crucible), "It's more than just a bunch of fat old men watching a fire..." :lol:

 

I'm lucky to have been standing beside them at the time.

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1 hour ago, Alan Longmire said:

"It's more than just a bunch of fat old men watching a fire..."

Yeah, you can't forget the booze!

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I don't remember what flavor the 'shine was that year.  It wasn't strawberry, maybe that year it was plain?  Or blueberry...

 

But yes, booze was involved.

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Thanks Jerod

 

the MIT definition helps when explaining the graph is upside down. I keep wanting to add solid  carbon to the CO/CO2 ratios at those temperatures..I am not sure if that is the case or the numbers are just an actual measurement of added quantities.

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