GB615590A - Process of separating alloys - Google Patents

Abstract

A process for separating alloys by fractional crystallization in which those phases which solidify first are caused to separate out at relatively cool points is characterized in that with controlled cooling of the melt, the abstraction of heat is effected only by way of a determinate crystallization surface and at the same time the melt is maintained in lively uninterrupted movement so that the temperature and the composition of the melt remain uniform throughout and only close to the crystallization surface is there set up a temperature and concentration drop in which the difference in temperature between the melt and the crystallization surface is maintained at from 5 DEG to 20 DEG C. The walls or part of the walls of the vessel containing the melt may be artificially cooled to form a crystallization surface the melt being stirred e.g. mechanically or by an alternating magnetic p field. Alternatively the surface of a hollow, mechanically driven stirrer may itself be artificially cooled to form a crystallization surface. The crystallization may be concluded as soon as the bath temperature has fallen to a value exceeding the eutectic temperature by about the temperature difference at the crystallization surface. An example is given of the production of an alloy containing 54.05 per cent tin, 41.50 per cent lead 3.55 per cent antimony and 0.15 per cent copper from a melt containing 53.04 per cent tin, 32.20 per cent lead, 12.08 per cent antimony and 2.46 per cent copper. The production of an eutectic aluminium-silicon alloy containing 12.9 per cent silicon from a melt containing aluminium, 31.5 per cent silicon and small quantities of iron and titanium, is also referred to.