Liquid-liquid contacting apparatus

Claim 1

Apparatus for effecting liquid-liquid contact in a plurality of stages between an aqueous liquid medium and an organic hydrophobic liquid medium capable of undergoing mass transfer with the aqueous liquid medium, comprising: a first mixer-settler; a second mixer-settler adjacent the first mixer-settler and sharing a common wall therewith; each mixer-settler comprising: a mixing chamber; agitator means in the mixing chamber for mixing the aqueous and organic hydrophobic liquid media so as to form a dispersion of globules of one medium dispersed in the other, which globules are of a size such that, upon standing under gravity, the dispersion is capable of disengaging substantially completely into two separate layers; an upper settling chamber above the mixing chamber; a lower settling chamber below the mixing chamber; and upper and lower baffle means extending across the mixer-settler so as to divide the mixing chamber from the upper settling chamber and the lower settling chamber respectively, each baffle means being adapted to provide a plurality of flow paths for liquid between the mixing chamber and the respective settling chamber and to permit maintenance in the respective settling chamber of conditions favouring dispersion disengagement despite turbulent mixing conditions in the mixing chamber; means for supplying the heavier medium of the two to the mixing chamber of the first mixer-settler; means for removing disengaged heavier medium from the lower settling chamber of the second mixer-settler; means for supplying the lighter medium of the two to the mixing chamber of one of the first and second mixer-settlers; means for removing disengaged lighter medium from the upper settling chamber of the other one of the first and second mixer-settlers; weir means in the flow path of lighter medium between the first and second mixer-settlers and having a length which exceeds half the length of the common wall, over which weir means disengaged lighter medium from the upper settling chamber of the said one mixer-settler may overflow; first conduit means for passing disengaged lighter medium that overflows the weir means from the said one mixer-settler to the mixing chamber of the said other mixer-settler; and second conduit means for passing disengaged heavier medium from the lower settling chamber of the first mixer-settler to the mixing chamber of the second mixer-settler.