Platinum Metals Rev., 1970, 14, (3), 87
Platinum Spiral Spinning Bands for Distillation Columns
Good design of fractional distillation columns results in high fractionating efficiency during operation at low pressures. A spinning band column to operate thus for Midland Silicones Limited incorporates this complex spiral screen band fabricated from platinum. It is nearly one metre in length and the teeth of the spiral gauge touch the glass wall of the still, causing violent agitation of the refluxing liquid and intimate contact between the descending liquid and ascending vapours. The spiral band throws both liquid and vapour on to the heated column walls and the pitch and direction of rotation create a downward pumping action to minimise holdup in the still and also to ensure steady distillation by preventing flooding. Platinum was chosen for the spiral because of its freedom from corrosion by the liquids and vapours in the still.