A method and an arrangement for improving a mineral flotation process

The specification relates to a method for improving a mineral flotation process. The method comprises adding coagulant(s) and/or flocculant(s) and/or flotation chemical(s) to an aqueous stream (100, 200a, 300a, 400b) of a minerals processing plant in order to facilitate formation of flocs including colloidal particles comprising electrochemically active metal(s), and in order to form a treated aqueous stream (101, 201, 301, 401), subjecting the treated aqueous stream (101, 201, 301, 401) to cleaning flotation in order to separate at least some of the colloidal particles comprising electrochemically active metal(s) and at least some of the microbes contained by the treated aqueous stream (101, 201, 301, 401) as a cleaning flotation overflow (103, 203, 303, 403) and in order to form a cleaning flotation underflow (104, 204, 304, 404), removing the cleaning flotation overflow (103, 203, 303, 403), and utilizing at least part of the cleaning flotation underflow (104, 204, 304, 404) as process water in minerals processing. The cleaning flotation comprises gas bubbles, at least 90 % of the gas bubbles having a diameter of from 0,2 to 250 µm.