The invention relates to a method and apparatus with which the aqueous solution from liquid-liquid extraction in the hydrometallurgical recovery of metals is purified from droplets of organic extraction solution. The aqueous solution is treated in a settling tank, where it is made to flow through a flow channel area with a reduced cross-section that extends over the width of the tank at least at one point. The flow channels are located in the lower section of the droplet coalescer according to the invention, with the upper section of the device being mainly solid.