Flotation apparatus and method for achieving flotation in a centrifugal field

A method for separating fine hydrophobic particles by flotation in a centrifugal field comprising:

• introducing a fluid suspension of particles coaxially into a cylindrical vessel at a first end, a substantial portion of the particles in the fluid suspension being fine particles and at least a portion of the particles in the fluid suspension being hydrophobic;
• creating a vortex in the vessel by introducing a second fluid into the vessel adjacent a second end in a generally tangential fashion and removing fluid from the vessel adjacent the first end in a generally tangential fashion, the vortex forming a centrifugal field in the vessel;
• sparging gas through a porous wall formed in at least a portion of the outer wall of the vessel, the gas forming finely dispersed bubbles which form bubble/particle aggregates with the hydrophobic particles in the fluid suspension;
• floating said bubble/particle aggregates towards the core of the vessel;
• and
• collecting the bubble/particle aggregates at the core of the vessel to create a froth phase, thereby achieving separation of said hydrophobic particles by flotation in the centrifugal field.

A flotation apparatus for obtaining separation of fine particles in a centrifugal field comprising:

• a chamber having a generally circular cross-section;
• a coaxial inlet at a first end of the chamber for introducing a particulate suspension into the chamber, a substantial portion of the particles in the particulate suspension being fine particles and at least a portion of the particles in the particulate suspension being hydrophobic;
• a coaxial outlet at a second end of the chamber for removing a froth phase from the chamber, said coaxial outlet having a substantially reduced cross-sectional area as compared to the chamber;
• means for introducing a fluid under pressure into the chamber, said fluid being introduced in a generally tangential fashion thereby creating a vortex in the chamber, the vortex forming a centrifugal field;
• a porous wall forming at least a portion of the outer wall of the chamber, said porous wall being capable of introducing gas in finely dispersed bubbles into the vortex of said chamber, said gas forming bubble/particle aggregates with the hydrophobic particles in the particulate suspension and said bubble/particle aggregates being floated towards the core of the chamber and there collecting to form the froth phase within the core of the chamber, thereby achieving separation of said hydrophobic particles by flotation in the centrifugal field;
• and
• a gas plenum enclosing the porous wall portion of the outer wall of the chamber, said gas plenum supplying the gas introduced through the porous wall into the chamber.

An air-sparged hydrocyclone comprising:

• a generally cylindrical vessel;
• a coaxial feed at a first end of the vessel for receiving a particulate suspension into the vessel, a substantial portion of the particles in the particulate suspension being fine particles and at least a portion of the particles in the particulate suspension being hydrophobic;
• a coaxial discharge at a second end of the vessel for allowing removal of a froth phase from the vessel, said coaxial discharge having a substantially reduced cross-sectional area as compared to the vessel;
• an inlet means for introducing a washing medium into the vessel, the inlet means being located adjacent and generally tangential to the second end of the vessel;
• an outlet means for removing particles and washing medium from the vessel, the outlet means being located adjacent and generally tangential to the first end of the vessel;
• a porous wall forming at least a portion of the outer wall of the vessel between the inlet means and the outlet means, said porous wall being capable of introducing air in finely dispersed bubbles into the vessel, the air forming bubble/particle aggregates with the hydrophobic particles in the particulate suspension and said bubble/particle aggregates being floated towards the core of the vessel and there collecting to form the froth phase within the core of the vessel, thereby achieving separation of the hydrophobic particles by flotation in a centrifugal field;
• and
• an air plenum enclosing the porous wall portion of the outer wall of the vessel.

A method for separating fine particles in a fluid suspension of particles comprising:

• obtaining a vessel having a circular cross-section;
• forming a porous wall in at least a portion of the outer wall of the vessel;
• enclosing the porous wall in a gas plenum;
• introducing a feed into the vessel, the feed including particles in a fluid suspension, a substantial portion of said particles being fine particles and at least a portion of said particles being hydrophobic;
• providing an outlet means for removing a material from the vessel;
• creating a centrifugal field in the vessel by creating a vortex in the vessel;
• sparging gas from the gas plenum through the porous wall and into the vortex, said gas forming finely dispersed bubbles which form bubble/particle aggregates with the hydrophobic particles in the fluid suspension;
• and
• floating said bubble/particle aggregates towards the core of the vessel and there collecting the bubble/particle aggregates to form a froth phase within the core of the vessel, thereby achieving separation of said hydrophobic particles by flotation in the centrifugal field.

A gas-sparged hydrocyclone for obtaining separation of fine particles in a centrifugal field comprising:

• a vertically oriented chamber, the chamber having a circular cross-section;
• inlet means for introducing a particulate suspension comprising hydrophobic particles into the chamber, a substantial portion of the particles in the particulate suspension being fine particles, the inlet means comprising a generally tangential entry and the tangential entry imparting a vortex flow to the particulate suspension, thereby creating a centrifugal field in the chamber;
• an overflow means for directing a froth phase out of the chamber, the overflow means comprising a vortex finder located at an upper end of the chamber and oriented coaxially with the chamber, said vortex finder having a substantially reduced cross-sectional area as compared to the chamber;
• an outlet means for removing an underflow product from the chamber, the outlet means comprising a discharge outlet at a lower end of the chamber and oriented coaxially with the chamber;
• and
• gas sparging means for introducing a gas into the chamber comprising a gas plenum surrounding the chamber and a porous wall between the gas plenum and the chamber for introducing gas from the gas plenum into the chamber, the gas forming finely dispersed bubbles which form bubble/particle aggregates with the hydrophobic particles in the particulate suspension, said bubble/particle aggregates being floated towards the core of the chamber and there collecting to form the froth phase within the core of the chamber, thereby achieving separation of said hydrophobic particles by flotation in the centrifugal field.