GB671054A - Process for producing aluminium and its alloys - Google Patents

Abstract

In a process for the production of aluminium alloys from aluminium scrap or ores, the ore when such as used is reduced to form a primary aluminium alloy, this primary alloy or scrap being then treated with a molten metal such as zinc, magnesium or mercury, which can be distilled, or with an alloy containing at least one such metal thus forming a liquid intermediary alloy containing aluminium and the extracting metal and a solid residue. These two products are separated by filtration and the solid residue, still wetted by the intermediary alloy is washed on the filter with pure extracting metal obtained by distillation from the intermediary alloy, the washing liquid being then used in a further extraction operation. The residue, after washing, may then distilled to recover extracting metal. The liquid intermediary alloy may be purified by filtration, e.g. on a refractory filter mass of sillimanite or quartzite grains the sizes of which decrease from bottom to top, or preferably this filtration may be performed in the separation furnace before the residue of separation is washed, the said residue being used as the filter mass. Separation may be performed by applying suction below the filter plate or pressure above or both simultaneously or successively. The applied pressure which may be 1-3 Kg./cm2 may be increased towards the end of the operation. Alternatively separation may be performed by centrifuging. Washing of the residue may also be performed with use of pressure or suction or both. Aluminium may be added to the liquid resulting from washing of the residue to facilitate wetting of the primary alloy with the extracting metal in the washing liquid. Extraction, separation and, if desired, purification may be performed on one perforated plate in the same furnace, the first two operations being made simultaneously. The washed residue may be added to aluminium alloys and subjected to extraction to obtain aluminium alloys containing determined amounts of the other metals which were present with the aluminium in the ore. According to an example, an alloy containing Al 88.7 per cent, Si 11 per cent and Fe 0.3 per cent, is produced by the process of the invention. Specification 537,400 is referred to.