Abstract: A settler for decanting mineral slurries includes a tank having a side wall, a bottom and a top, an outlet for a thickened slurry at the bottom of the tank, a first overflow outlet for withdrawing an overflow stream of a clarified liquid, a slurry inlet means for introducing fresh slurry into the tank, the slurry inlet means having a slurry opening through which fresh slurry joins a body of slurry in the tank, and a stirrer having a vertical axis around which the stirrer rotates or reciprocates, in said settler the slurry opening is displaced laterally relative to said vertical axis of the stirrer and said slurry inlet means comprises mixing means. A separation installation includes the above settler and a method for separating a clarified liquid from a thickened slurry of a mineral slurry.

Abstract: A process for producing alumina trihydrate includes a digestion step, a separation step, and a precipitation step the separation step including: b1) pretreating a slurry from the digestion step by adding a flocculant to said slurry and mixing the flocculant and the slurry, b2) settling the resulting flocculated slurry in a gravity settler vessel, b3) determining a measured value representative of the concentration of solid particles in the resulting clarified liquor, b4) comparing the measured value with a predetermined threshold, b5) feeding said clarified liquor directly to the precipitation step, while the measured value is less than said predetermined threshold, and b6) redirecting said clarified liquor to the pre-treatment step b1), when the measured value is more than said predetermined threshold. An installation may be configured for operating said process.

Abstract: A process for producing alumina trihydrate includes a digestion step, a separation step, and a precipitation step the separation step including: b1) pretreating a slurry from the digestion step by adding a flocculant to said slurry and mixing the flocculant and the slurry, b2) settling the resulting flocculated slurry in a gravity settler vessel, b3) determining a measured value representative of the concentration of solid particles in the resulting clarified liquor, b4) comparing the measured value with a predetermined threshold, b5) feeding said clarified liquor directly to the precipitation step, while the measured value is less than said predetermined threshold, and b6) redirecting said clarified liquor to the pre-treatment step b1), when the measured value is more than said predetermined threshold. An installation may be configured for operating said process.

Abstract: A settler for decanting mineral slurries includes a tank having a side wall, a bottom and a top, an outlet for a thickened slurry at the bottom of the tank, a first overflow outlet for withdrawing an overflow stream of a clarified liquid, a slurry inlet means for introducing fresh slurry into the tank, the slurry inlet means having a slurry opening through which fresh slurry joins a body of slurry in the tank, and a stirrer having a vertical axis around which the stirrer rotates or reciprocates, in said settler the slurry opening is displaced laterally relative to said vertical axis of the stirrer and said slurry inlet means comprises mixing means. A separation installation includes the above settler and a method for separating a clarified liquid from a thickened slurry of a mineral slurry.

Abstract: An apparatus for refining a process liquor that includes solids, which apparatus includes a vessel having a base and a side wall that define an internal volume for containing the process liquor and for allowing gravity settling of the solids in the liquor, whereby to produce a refined liquor toward a top of the internal volume and a slurry toward a bottom of the internal volume, the apparatus further includes solids displacement elements disposed within the internal volume for directing settled solids and/or settling solids in the vicinity of the side wall or of the base toward a flow path of the slurry being extracted from the slurry outlet. A processing plant including the above refining apparatus and a method for refining a process liquor.

Abstract: An apparatus for refining a process liquor that includes solids, which apparatus includes a vessel having a base and a side wall that define an internal volume for containing the process liquor and for allowing gravity settling of the solids in the liquor, whereby to produce a refined liquor toward a top of the internal volume and a slurry toward a bottom of the internal volume, the apparatus further includes solids displacement elements disposed within the internal volume for directing settled solids and/or settling solids in the vicinity of the side wall or of the base toward a flow path of the slurry being extracted from the slurry outlet. A processing plant including the above refining apparatus and a method for refining a process liquor.