New long-life impregnated graphite rotor impeller & shaft to be used for degassing in molten auminium for SNIF, ALPUR and STAS
Graphite rotors, impellers and shafts are widely used for dispersing hydrogen of inline degassing aluminum. We are specialised in all in-line degassers such as STAS, Novelis ALPUR, Pyrotek SNIF and Hertwich.
During aluminum and aluminum alloy smelting, hydrogen produced by chemical action with steam diffuse in molten aluminum, which will cause inner structural defect to aluminum products. In order to avoid such defect, most aluminum factories apply dissolved gas floating method to purify molten . i.e. inert gases such as nitrogen, argon is injected into molten aluminum, and hydrogen will be brought to molten aluminum surface with spread and rise of inert gas.
A twirling graphite rotor shatters nitrogen (or argon), which is blown into melting inline degassing aluminum, into profuse bubbles that disperse in the liquid metal. Regarding gas pressure difference and surface adsorption principle, bubbles in the melt absorb hydrogen and oxidation slag inclusion which are taken out to surface of the melt with the rise of the bubbles, so that the melt can be purified.
Nowadays, as an alternative to graphite rotors, impellers and shafts, ultrasonic degassing in molten aluminium has now become the standard. A 20 kHz ultrasonic generator creates cavitation which disperses the hydrogen in the aluminium bath. This technology is also used for ultrasonic grain refinement and ultrasonic micro-alloying in molten non-ferrous melts.