Method and apparatus for direct recovery of mineral values as a bubble-solids aggregate

A method for the recovery of hydrophobic particles from a slurry that is comprised of water, the hydrophobic particles, and a hydrophilic component, the method comprising:

• (i) exposing the slurry to a gas stream to permit gas bubbles to adhere to the hydrophobic particles,
• (ii) pumping the slurry through a vessel having one or more slurry outlets, each of the outlets including a control valve that is operated to maintain pressure within the vessel at a level that maintains a gas hold-up in the vessel of between 30 and 90% and that maintains a bubbly flow without the formation of a slurry froth interface or a froth,
• (iii) discharging a portion of the water of the slurry, together with gas bubbles attached to hydrophobic particles, out of the vessel, with a portion of the water of the slurry and the hydrophilic component remaining in the vessel, and
• (iv) extracting a portion of the hydrophilic component from the vessel as tailings,
• wherein the slurry is maintained at above atmospheric pressure when within the vessel,
• wherein the vessel comprises a direct flotation device, the direct flotation device comprised of a first, a second, a third and a fourth zone, the first zone comprising a diameter-reduction section, the second zone comprising a water flush section, the third zone comprising a secondary diameter-reduction section, the fourth zone comprising a conduit to deliver the portion of the water of the slurry, together with gas bubbles attached to hydrophobic particles, to a control valve at a discharge outlet, and
• wherein the step of pumping the slurry through the vessel includes pumping the portion of the water of the slurry, together with gas bubbles attached to hydrophobic particles, consecutively through the first, second, third and fourth zones, and then through the control valve to discharge the portion of the water of the slurry, together with gas bubbles attached to hydrophobic particles, from the vessel as a bubbly flow.