is used for scraping off and cleaning of ceramic crucibles in aluminium crucible melting furnaces. This consists of a device with 3 or 4 shovels, which if necessary can be operated individually under pneumatic power like a compressed air hammer. After the 1st downward stroke, the shovels are moved upward, rotated through the specified angle and then lowered 2 – 5 times to clean the crucible. About 300 mm of aluminium are left in the crucible, so that the residue can then be removed from the furnace with the aid of a modified “slag excavator”. This work must be carried out with the crucible still in the warm, operating condition, since if the crucible is too cold, not only will the dross be removed, but the cru- cible wall can also be severely damaged. Mechanical milling devices have not proven effective in this application.
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