Summary and Results

The mixed shavings fractions are fed into a slightly acidic separation bath separately. The aluminium shavings passivate on the surface through the formation of a thin but very dense layer of oxide. In contrast to this, the surface of the magnesium shavings is partially dissolved by the weak acid. In the process, a very slight but adequate amount of gaseous hydrogen forms. Additives guarantee the adhesion of the resulting and constantly reforming hydrogen bubbles on the surface of the magnesium shavings. As a result, they experience enough buoyancy to be transported to the surface of the bath where they are removed from the separating tank. In contrast, the passivated aluminium shavings sink to the bottom where they are also removed. This way, very good purities of the individual shavings fractions (up to 95 – 100% purity) are achieved with real samples. Impurities such as residue from metalworking fluids and its effect on the separation process were studied and do not represent a problem worth mentioning.