Abstract: The invention relates to the field of water purification. A method for sening water by way of its electrochemical treatment involves causing water to pass in the form of two streams through anode and cathode chambers of a membrane electrolyzer. According to the invention, the water stream being fed to the anode chamber is preliminarily softened before supplying it to the anode chamber, and this stream is in the form of catholyte after the separation of precipitating hardness salts therefrom, anolyte being used as the end product. An electrolyzer for softening water has a casing divided by membranes into anode and cathode chambers, respectively.

Abstract: A method for concentrating ores of non-ferrous metals by flotation, wherein a pulp and air mixture is prepared and fed through a nozzle under pressure to the bottom part of a mixing chamber. The mixture is directed toward an impact wall in such a manner that after the jet hits against the wall air bubbles of a diameter not exceeding 150-200 .mu.m are formed. The flows resulting from the impact against this wall are directed toward each other in such a manner as to collide in the top part of the mixing chamber at a velocity maximum 90-100 cm/s and at an angle 40-75.degree. with respect to the vertical axis of the mixing chamber, the resultant flow being deaerated, and a resultant froth layer removed. A flotation machine has a mixing chamber having a nozzle for feeding thereto a pulp and air mixture and an impact wall disposed directly adjacent to the nozzle, the mixing chamber having walls which are so shaped as to provide for carrying out the abovedescribed method.