Method and apparatus for contacting bubbles and particles in a flotation separation system

Apparatus for contacting bubbles and particles in a flotation separation system, said apparatus comprising:

• a contactor arranged to receive under pressure a supply of feed slurry incorporating particles suspended in a liquid and a supply of gas, the contactor being arranged to mix the slurry with the gas forming a gas-liquid bubbly two-phase mixture;
• an outlet from the contactor configured to provide a restriction to the flow of mixture therethrough and maintain the mixture within the contactor under pressure, the outlet further being configured to induce a supersonic shockwave within the mixture passing therethrough, and configured such that when slurry and gas are fed into the contactor at feed rates and pressures determined to form said gas-liquid bubbly two-phase mixture and force the mixture through the outlet at a rate that induces said supersonic shockwave within the mixture reducing the size of the bubbles within the mixture and bringing those bubbles into intimate contact with particles in the mixture;
• and
• a separation cell including a mixture-directing device, the mixture-directing device arranged to receive mixture from the outlet and to control the release of that mixture into the separation cell,
• wherein the mixture impinges against adjacent surfaces of the mixture directing device to create a high shear environment for the mixture before allowing bubbles with attached particles to rise to the surface of liquid within the cell.