Sparger device for sparging a fluid into a slurry tank, flotation apparatus and system having such sparger device, and method for setting control fluid pressure of a sparger device

A sparger device for sparging fluid into a slurry tank, said sparger device comprising:

• a hollow elongated body having a nozzle opening at a distal end thereof for sparging a sparging fluid flow to a slurry tank from an inside of the hollow elongated body, the inside of the elongated hollow body being configurable for fluid communication with a sparging fluid supply, when in use:
• a needle, movably arranged along a longitudinal axis of the sparger device within the hollow elongated body, the needle having a first end for opening and closing the nozzle opening in order to allow, and respectively block fluid flow via the nozzle opening, and
• a control device coupled with a second end of the needle, the control device being arranged to actuate the needle along the longitudinal axis so as to open or close the nozzle opening,
• wherein the control device comprises a control chamber partitioned by a piston member into a first portion and second portion, the piston member being coupled with the needle, and configured to be movable within the control chamber along the longitudinal axis in response to a pressure differential between the first portion and the second portion, such that:
• a lower fluid pressure in the first portion with respect to that of the second portion will move the needle against the nozzle opening, thereby closing it, and respectively,
• a higher fluid pressure in the first portion with respect to that of the second portion will move the needle away from the nozzle opening, thereby opening it,
• wherein the first portion of the control chamber being in fluid communication with the inside of the elongated hollow body, thereby defining the fluid pressure within the first portion to equal with that of the sparging fluid supply, when in use, and
• the second portion of the control chamber being configurable for being in fluid communication with a control fluid, thereby defining the fluid pressure within the second portion to equal with that of a control fluid, when in use,
• whereby backflow of slurry from the slurry tank to the sparger device via the nozzle opening may be prevented by providing a control fluid pressure exerting, on the piston member, a force greater than that exerted on the first end of the needle by the fluid pressure of the slurry tank at a level of the sparger device, wherein the control device comprising a pressure sensor for providing information indicative of the fluid pressure within the second portion of the control chamber, and
• wherein the sparger device comprises a charging valve for charging the second portion of the control chamber with a desired control fluid pressure, said charging valve being provided as a pneumatic or hydraulic quick coupling connector.