Plasma arc reactor for the production of fine powders

A process for producing a powder from a solid feed material, comprising the steps of:

• (a) introducing a plasma gas into the space between first and second electrodes of a plasma arc reactor,
• (b) generating a plasma arc in the space between the first and second electrodes,
• (c) feeding a length of a solid material through a channel in the first electrode to exit via an outlet thereof into the plasma arc, whereby the solid feed material is vaporised, and
• (d) cooling the vaporised material to condense a powder.

A process for producing a passivated aluminium powder from a solid feed material of aluminium wire, which process comprises:

• a) supplying inert gas to a plasma arc reactor and generating an inert plasma in the reactor,
• b) feeding aluminium wire into the inert gas plasma, whereby the aluminium is vaporized,
• c) cooling the vaporized aluminium with an inert gas to condense a powder of aluminium, and
• d) oxidizing the surface of the powder of aluminium with a passivating gas, and wherein the reactor comprises
• i) a first electrode having a channel running therethrough, and
• ii) a second electrode spaced apart from the first electrode by a distance sufficient to achieve a plasma arc therebetween, an outlet of the channel of the first electrode exiting into the space between the first and second electrodes,
• wherein said step of feeding aluminium wire into the inert gas plasma comprises passing the aluminium wire through the channel to exit therefrom via the outlet into the space between the first and second electrodes.