Production of grey cast iron powder via target jet milling

Target jet milling was used for the first time to convert cast iron scraps to powder. An experimental apparatus was designed which comprised a compressor, a mixing section, a nozzle, an impact chamber and two suction machines. Milling parameters i.e. the target to nozzle distance, the feed rate and the impact angle were optimized through appropriate tests. The travel distance of 8 cm and the impact angle of 90° were found to be ideal parameters of milling. The effect of feed rate on production of powders greater than 45 μm was found to be opposite to the production of the fines (< 45 μm). Investigation of the fragmentation procedure of particles revealed that, the existence of graphite flakes in cast iron matrix plays the most important role in particle breakage.

A mixture of compressed air and grey cast iron scrap was collided onto a solid target inside a chamber to produce powder. The set up consisted of: (A) Compressor; (B) Mixing section; (C) Vibratory feeder; (D) Nozzle; (E) Target; (F) Impact chamber; (G) Suction machine.Figure optionsDownload as PowerPoint slideHighlights
► Jet milling can be used to produce cast iron powder from its scrap.
► There exists an optimum travel distance and an ideal impact angle for jet milling.
► The effect of feed rate on powder production larger and less than 45 μm is opposite.
► Attrition in nozzle plays the major role in production of fines (< 45 μm).
► Graphite flakes in matrix are of great importance in the fragmentation process.