The degassing filtering equipment for continuously processing molten aluminum and aluminum alloy to remove most of solid particles and gas, therefrom includes a chamber, having an inlet for receiving a stream of molten aluminum to be purified, and an outlet for discharging purified molten aluminum, the device enters the chamber into multiple purification stages, including: a deslagging stage, which has a filter medium adapted to be at least partially immersed in the molten metal; a fluxing stage, which includes a device for introducing a fluxing gas into the molten metal. The stage includes a device for adsorbing impurities from the molten metal, the adsorption device includes a plurality of refractory elements on which the molten metal flows, and the refractory element of the adsorption device includes a substantially flat horizontally arranged. The plates are arranged parallel to each other and spaced apart with respect to the flow direction of the container. The molten metal passes through the adsorption stage and the filtering step. The filter includes a rigid filter medium for filtering out solid impurities from the molten metal passing through it.
After passing through the refractory filter, the molten metal is transferred to a second or fluxing stage wherein a series of vertically arranged baffles direct the molten metal flow in countercurrent relation to a pair of spaced diffuser heads from which is dispersed a fluxing gas. Thereafter, the molten metal is directed through a third or adsorption stage which comprises a series of parallelly arranged horizontal plates formed of a refractory material having an adsorptive affinity for one or more of the impurities known or expected to be present in the molten metal. Minute particles of such impurities adhere to the surfaces of the adsorptive plates and are thereby removed from the molten aluminum.
From the adsorption stage, the molten metal is subjected to a fourth or final purification treatment by filtration through a filter medium formed of rigid, porous refractory material disposed immediately upstream of the treatment system outlet to the tundish of the continuous casting machine. The porous filter is designed in such manner as to provide a surface area substantially greater than the total cross-sectional area of the flow path and, preferably, at least twice as great.
The degassing filtering equipment is particularly advantageous in that the plural purification stages insure that the occurrences of inclusions and voids caused by particulate matter and entrapped gases in the continuously cast product are minimized.
