Solvent extraction settler arrangement

A solvent extraction settler arrangement adapted for hydrometallurgical liquid-liquid extraction processes, comprising

• a settler tank having a feed end and a discharge end which is opposite and at a distance in relation to the feed end, said settler tank being arranged to separate solution phases from a dispersion of said phases comprising a heavy solution phase and a light solution phase, while said dispersion fed from the feed end flows to the discharge end,
• a discharge launder arranged at the discharge end of the settler for collecting and discharging the heavy solution phase, having a layer of entrained light solution phase on the surface of the heavy solution phase, separated as an underflow from the dispersion, the discharge launder including a first end, a first outlet arranged at the first end, and a closed second end, and
• an outlet box connected to the first end of the discharge launder to receive the heavy solution phase flowing via the first outlet from the discharge launder, the outlet box comprising a vertical shaft defined by a side wall, a bottom and a top wall, an inlet adjacent the upper part of the shaft for receiving the heavy solution phase together with said layer of entrained light solution phase flowing from the first outlet of the discharge launder, and a discharge outlet for discharging the heavy solution phase from the outlet box, said discharge outlet being located below the level of the inlet, wherein the outlet box comprises an inner tube arranged vertically inside the shaft and to extend from the bottom to through and above the top wall, said inner tube being spaced from the side wall of the shaft to define an intermediate space between the inner tube and the vertical shaft, the inner tube having an inner space and an opening at the lower part of the inner tube adjacent the bottom to form a flow path for the heavy solution phase to flow from the intermediate space to the inner space, and the inner tube having an outlet above the opening, said outlet being said discharge outlet for discharging the heavy solution phase from the outlet box, and that the shaft comprises a second outlet which is separate in relation to the discharge outlet and above the level of the discharge outlet, and which second outlet opens through the side wall to the intermediate space at a location adjacent to the upper end of the shaft and at the level of said layer of entrained light solution phase for discharging said layer of entrained light solution phase from the intermediate space, whereby the heavy solution phase is discharged via the discharge outlet and the layer of entrained light solution phase is discharged via the second outlet.