Abstract: The invention relates to a filter aid for filtering a liquid, such as beer, in a filtration device working on a defined filtration velocity, said filter aid consists essentially of particles of a material A, wherein the flotation velocity UoA is measured as Formula (I): wherein dA is the diameter of the particle, &mgr; is the viscosity of the fluid, r is the density of the fluid and &rgr;a is the density of the particle. The invention further relates to the use of said filter aid as a precoating material in a candle filtration device and to the candle filtration device comprising a number of candles provided with a precoat consisting essentially of the filter aid according to the invention and to a filtrated liquid, for example alcohol and more in particular beer, obtained via a filtration method using a candle filtration device.

Abstract: A chemical treatment of an aluminum cathode used in zinc electrowinning consists of contacting the affected areas of the aluminum cathode or the entire surface of the cathode with a dilute hydrochloric acid aqueous solution.