GB1250277A - - Google Patents

Abstract

1,250,277. Crucibles. SWISS ALUMINIUM Ltd. 21 Feb., 1969 [23 Feb., 1968], No. 9568/69. Heading F4B. [Also in Division C7] In a process in which a melt of Al or Mg or Albase or Mg-base alloy is treated in an essentially closed container with a non-metallic agent that is gaseous at the temperature of the melt, the treatment resulting in the escape from the melt of a vapour that condenses to a solid at room temperature, the said vapour is condensed as a solid on a surface within the container above the melt by cooling that surface. Apparatus for the introduction of a gaseous agent is shown in Fig. 1 and comprises crucible 1 containing melt 2. Pipe 3 for the agent passes through cover 4 which is cooled by passage of water through pipe 6. Apparatus is also described for the introduction of (a) solid agent where the agent is contained in a bell with a perforated bottom plate, the bell being lowered into the melt (Fig. 3, not shown); (b) solid or liquid agent where a volatilization chamber for the agent is mounted inside the crucible or other vessel and communicates with the interior of the melt via a tube (Fig. 4, not shown, and, for solid agents only, Fig. 5, not shown). In the modification shown in Fig. 7, molten metal flowing to a continuous casting mould through trough 40 is treated with gas introduced through tube 46 within the container formed by deepened portion 41 of the trough and baffles 42, 43. In further modifications, (1) solid treating agent may be held at the bottom of the crucible or other vessel by a perforated plate on to which the metal is allowed to flow, (2) the agent may be introduced as briquettes, (3) liquid agents may be absorbed by a solid, e.g. kieselguhr, and introduced in this form, (4) solid or liquid agents may be volatilized outside the container and introduced as vapour, and (5) vapour escaping from the melt may be condensed on a coiled pipe, e.g. air-cooled, which passes through the crucible or other vessel (Fig. 6, not shown).