A method to remove oil from an oily water stream includes the step of pressure controlling a release of dissolved gases from the stream as the stream passes through two or more stages of gas flotation treatment. The operating pressure of the first stage of flotation treatment is purposefully reduced relative to that of an upstream unit so that a certain controlled percent volume of dissolved gases is released. The operating pressure of the second stage of flotation treatment is then purposefully reduced relative to that of the first stage so that another controlled percent volume of dissolved gases is released. Any subsequent flotation treatment stage is at a lower operating pressure than that of the previous stage so that the subsequent treatment stage releases a controlled percent volume of dissolved gases. By controlling the operating pressure in this way, overall separation performance is improved.

The flotation apparatus includes a flotation vessel and a cover for closing an upwards open opening of the flotation vessel, wherein the cover and the flotation vessel limits a vessel space for receiving fluid, and an agitating means having a rotatable axis extending through a first aperture in the cover. The rotatable shaft is rotatable supported at a bearing housing outside the vessel space. A connection arrangement surrounds the rotatable shaft between the bearing housing and the cover.

The flotation apparatus includes a flotation vessel and a cover for closing an upwards open opening of the flotation vessel, wherein the cover and the flotation vessel limits a vessel space for receiving fluid, and an agitating means having a rotatable axis extending through a first aperture in the cover. The rotatable shaft is rotatable supported at a bearing housing outside the vessel space. A connection arrangement surrounds the rotatable shaft between the bearing housing and the cover.

A method to remove oil from an oily water stream includes the step of pressure controlling a release of dissolved gases from the stream as the stream passes through two or more stages of gas flotation treatment. The operating pressure of the first stage of flotation treatment is purposefully reduced relative to that of an upstream unit so that a certain controlled percent volume of dissolved gases is released. The operating pressure of the second stage of flotation treatment is then purposefully reduced relative to that of the first stage so that another controlled percent volume of dissolved gases is released. Any subsequent flotation treatment stage is at a lower operating pressure than that of the previous stage so that the subsequent treatment stage releases a controlled percent volume of dissolved gases. By controlling the operating pressure in this way, overall separation performance is improved.

A method to remove oil from an oily water stream includes the step of pressure controlling a release of dissolved gases from the stream as the stream passes through two or more stages of gas flotation treatment. The operating pressure of the first stage of flotation treatment is purposefully reduced relative to that of an upstream unit so that a certain controlled percent volume of dissolved gases is released. The operating pressure of the second stage of flotation treatment is then purposefully reduced relative to that of the first stage so that another controlled percent volume of dissolved gases is released. Any subsequent flotation treatment stage is at a lower operating pressure than that of the previous stage so that the subsequent treatment stage releases a controlled percent volume of dissolved gases. By controlling the operating pressure in this way, overall separation performance is improved.

The flotation apparatus includes a flotation vessel and a cover for closing an upwards open opening of the flotation vessel, wherein the cover and the flotation vessel limits a vessel space for receiving fluid, and an agitating means having a rotatable axis extending through a first aperture in the cover. The rotatable shaft is rotatable supported at a bearing housing outside the vessel space. A connection arrangement surrounds the rotatable shaft between the bearing housing and the cover.

An arrangement for recirculation of flotation gas in a mineral flotation process wherein the flotation gas volume fluctuations are handled by a closed pressure equalization loop including an apparatus for storing gas and adsorbing changes of gas pressure; a flushing line for connecting the pressure side of the primary gas recirculation loop to the apparatus for storing gas and adsorbing changes of gas pressure for allowing expulsion of a fraction of the flotation gas from the primary gas recirculation loop; and a suction line for connecting the suction side of the primary gas recirculation loop to the apparatus for storing gas and adsorbing changes of gas pressure, whereby the suction line comprises a pressure reducer for restricting flotation gas flow through the suction line.

An arrangement for recirculation of flotation gas in a mineral flotation process wherein the flotation gas volume fluctuations are handled by a closed pressure equalization loop including an apparatus for storing gas and adsorbing changes of gas pressure; a flushing line for connecting the pressure side of the primary gas recirculation loop to the apparatus for storing gas and adsorbing changes of gas pressure for allowing expulsion of a fraction of the flotation gas from the primary gas recirculation loop; and a suction line for connecting the suction side of the primary gas recirculation loop to the apparatus for storing gas and adsorbing changes of gas pressure, whereby the suction line comprises a pressure reducer for restricting flotation gas flow through the suction line.

Apparatus is provided featuring a first and second cells. The first cell receives an ore slurry having mineral particles of interest, receives unexpanded polymer microspheres comprising a surface having mineral collector chemistry attached thereto with molecules for attaching the mineral particles of interest, causes the unexpanded polymer microspheres to expand substantially in volume into expanded polymer microspheres having a substantially increased sphere surface area, and provides an expanded polymer microsphere foam layer comprising the expanded polymer microspheres with attached mineral particles of interest. The second cell receives the expanded polymer microsphere foam layer, and causes the expanded polymer microspheres to collapse substantially in volume into collapsed polymer microspheres having a substantially reduced sphere surface area that results in a mechanical shearing off of the attached mineral particles of interest. The second cell may also provide a mineral concentrate output having the mineral particles of interest.

Apparatus is provided featuring a first and second cells. The first cell receives an ore slurry having mineral particles of interest, receives unexpanded polymer microspheres comprising a surface having mineral collector chemistry attached thereto with molecules for attaching the mineral particles of interest, causes the unexpanded polymer microspheres to expand substantially in volume into expanded polymer microspheres having a substantially increased sphere surface area, and provides an expanded polymer microsphere foam layer comprising the expanded polymer microspheres with attached mineral particles of interest. The second cell receives the expanded polymer microsphere foam layer, and causes the expanded polymer microspheres to collapse substantially in volume into collapsed polymer microspheres having a substantially reduced sphere surface area that results in a mechanical shearing off of the attached mineral particles of interest. The second cell may also provide a mineral concentrate output having the mineral particles of interest.