Abstract: The invention concerns a method for separating solid and liquor components of a process slurry comprising solid material entrained in a liquor, said method comprising: (a) a pre-treatment step of adding a flocculent to the process slurry and mixing the flocculent and the slurry by selecting a higher extent of mixing in an early stage of said step than in a later stage of said step, and (b) a solid/liquor separation step of allowing separation of solid material, including aggregates of solid material, and liquor of said process slurry to produce process outputs of a clarified liquor and solid material with some entrained liquor. The invention also concernes a method and an apparatus for adding a flocculent to a process slurry.

Abstract: Method and apparatus for separating components of slurries by gravity settling thereby forming a thickened slurry and a clarified liquid. The apparatus comprises a vessel for decanting a volume of slurry, the vessel having a top and an interior formed by a side wall and a bottom wall for holding the slurry, a slurry inlet means, an outlet for the clarified liquid near the top of the vessel, and a slurry withdrawal apparatus for removal of the thickened slurry from the vessel at or near the bottom wall thereof. The slurry withdrawal apparatus physically engages a portion of the slurry within the vessel interior and transports it through a vessel outlet.

Abstract: Method and apparatus for separating components of slurries by gravity settling thereby forming a thickened slurry and a clarified liquid. The apparatus comprises a vessel for decanting a volume of slurry, the vessel having a top and an interior formed by a side wall and a bottom wall for holding the slurry, a slurry inlet means, an outlet for the clarified liquid near the top of the vessel, and a slurry withdrawal apparatus for removal of the thickened slurry from the vessel at or near the bottom wall thereof. The slurry withdrawal apparatus physically engages a portion of the slurry within the vessel interior and transports it through a vessel outlet.

Abstract: The invention relates to a settler for decanting mineral slurries and a method thereof. The settler comprises a tank for holding and decanting a body of slurry to form a thickened slurry as a lower layer and a clarified liquid as an upper layer, the tank having a side wall, a bottom and a top, an outlet for the thickened slurry at the bottom of the tank, an outlet for the clarified liquid layer near the top of the tank, a slurry inlet means near the top of the tank for introducing fresh slurry into the tank, the slurry inlet means having a slurry opening through which fresh slurry joins the body of slurry in the tank, and a stirrer having a generally vertical axis around which the stirrer rotates or reciprocates. The slurry opening is displaced laterally relative to the generally vertical axis of the stirrer and the slurry inlet means is configured to allow the fresh slurry to enter the slurry body without accumulating solids from the fresh slurry at the slurry opening.

Abstract: The invention relates to a settler for decanting mineral slurries and a method hereof. The settler comprises a tank for holding and decanting a body of slurry to form a thickened slurry as a lower layer and a clarified liquid as an upper layer, the tank having a side wall, a bottom and a top, an outlet for the thickened slurry at the bottom of the tank, an outlet for the clarified liquid layer near the top of the tank, a slurry inlet means near the top of the tank for introducing fresh slurry into the tank, the slurry inlet means having a slurry opening through which fresh slurry joins the body of slurry in the tank, and a stirrer having a generally vertical axis around which the stirrer rotates or reciprocates. The slurry opening is displaced laterally relative to the generally vertical axis of the stirrer and the slurry inlet means is configured to allow the fresh slurry to enter the slurry body without accumulating solids from the fresh slurry at the slurry opening.

Abstract: A process is described for removing dissolved silica from an alkaline solution containing sodium aluminate, e.g. a Bayer process solution. The process comprises contacting the alkaline solution with a slowly stirred bed of particles comprising coarse silica sand or a mixture of coarse silica sand and particles of sodalite, whereby the dissolved silica is precipitated out of solution to form a precipitation of desilication product dispersed in the solution and separating the desilication product solids from the alkaline solution to obtain a desilicated alkaline solution.