Alcan International Limited

Rio Tinto Alcan International Limited

Andrew N Carruthers

Guy Peloquin

Renald Dufour

Alain Boivin

Kwat I The

Donald L Puxley

Guy Simard

Bryan A Hiscox

Robert L Clegg

Jens Fenger

Claude Boulanger

Rock Lemyre

Benny E Raahauge

Hans-Peter Elkjaer

Hamish Baxter

Jose Gil Pulpeiro

Donald Puxley

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. The apparatus may include an elongated, rotatable, open spiral-shaped element extending a distance into the vessel from outside near the bottom wall of the vessel, the open spiral-shaped element being in direct and open communication with the interior of the vessel over at least a significant portion of the distance, and a rotational drive mechanism for rotating the open spiral-shaped element, at least intermittently.

Apparatus for production, withdrawal and transfer of highly viscous slurry

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.

Apparatus for and method of settling of mineral slurries

Process and apparatus for drying liquid-borne solid material

A process for producing strong, essentially dust-free agglomerates from dust created by an industrial operation carried out, for example, on an ore or mineral, e.g. during the thermal conversion of a material containing predominantly gibbsite to sub-alpha alumina by a multistage thermal process having at least one intermediate stage. The process comprises grinding particles of binder material containing undercalcined alumina to a median particle size of less than 30 microns and to a specific surface area in the range of 90-300 m.sup.2 /g; combining about 1-4 parts by weight of the dust with one part by weight of the ground binder material to form combined solids; mixing the combined solids with water to produce agglomerates, the total amount of added water being about 0.8-1.2 parts by weight for every part by weight of the ground binder material, plus about 0.08 to 0.12 parts by weight for every part by weight of the dust; and optionally aging the resulting agglomerates in a closed environment at a temperature of at least 80.degree. C. for at least one hour in at least 50% humidity. The water is mixed with the combined solids by intensive mixing in a mixer equipped with a mixing motor, the water being added according to the following scheme: (a) 40-80% of the total amount of water is added to the combined solids at a rate such that no more than 10 minutes are required for complete addition; (b) optionally allowing a period of time to pass after the addition of the water in step (a) before proceeding further while continuing the intensive mixing; (c) commencing the addition of the remainder of the water and measuring a characteristic of said mixture corresponding to its viscosity and using the measurement as a reference value; and (d) continuing the addition of the remainder of the water while continuing to measure the characteristic of the mixture, the water being added at such a rate that the characteristic of the mixture remains the same as the reference value during the addition or varies by less than .+-.5%.

Process for producing agglomerates from dusts

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Beaconsfield, Canada

Andrew N Carruthers