Abstract: Mercury particles which are difficult to strip from sewage waters of industries employing mercury compounds, due to their extremely tiny size, can be coalesced into larger mercury drops by applying a strong magnetic field to the liquor which contains such tiny particles.

Abstract: A method for stripping pollutant metals from sewage waters from ore-treatment installations is disclosed, which comprises the step of using, in a short-circuited electrode system through which the waters to be purified are flowed, a compound of an element which is other than the cathode metal and is more electro-positive than the anode element. Striking results are obtained by treating vanadium-containing sewage waters from gallium-ore treatment plants with silver sulfate in a copper-iron electrode system. The method can be employed to recover other transition metals from liquors which contain them.

Abstract: A method is disclosed for stripping mercury from mercury-containing sludges, the improvement consisting in that the sludges are first dried and then roasted, all these operations being carried out under a subatmospherical pressure, a final condensation of the vapor phases takes place under superatmospherical pressure. A high efficiency of recovery is thus warranted.