Our aim is to produce Powder metallurgy grade micronized iron powder by using sponge iron. The problem is that at last stage of powder production when powder is crossing hydrogen belt furnace, it turns into a crumbly cake and it is necessary to grind it after so. On the other hand, when we use conventional methods of grinding, our powder starts to get oxidized and in some cases it even burns, so we need another method of grinding.
Kaveh Eftekharnia
Small metal particles are pyrophoric in air. You'll not make such materials by grinding larger material as comminution energy is basically changed into heat, sound and light. You could rigidly exclude oxygen (e.g. in an Ar atmosphere) but as soon as air is admitted to the chamber then immediate oxidation will result usually with sparking/ignition.
Only routes are to make the material in colloidal suspension with appropriate protective steric layers. Now, if Fe metal is needed finely divided for (say) a catalytic reaction then it could be produced in situ by (say) H2 reduction. One other thought occurs to me and that's the milling of the material in oleic or stearic acids giving a huge 'oily/soapy coating that may delay oxygen migration through to the metal.
Here's a video: http://my.rsc.org/video/183
Dalibor Matýsek
The same (pyrophoric) problem arises when air is admitted to the system. You’d need to keep the fine powder permanently under nitrogen.
Hi Dr Kaveh Eftekharnia . I hope the following link could help:
https://www.np-maliodkrywcy.pl/06-Fri/98894369.html
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