Abstract: Methods and apparatus are provided, which separate out at least a portion of fine dust, including fluoride, from recycled alumina. The difference in natural drop velocity and flow properties of fine and coarse particles is used to effect the separation.

Abstract: A method and an apparatus for cleaning flue gases with particulate slaked lime are described. In the method, burnt lime is dry-slaked with water to a moisture content of at least 5% by weight, and the slaked lime is contacted with the flue gases within 1 minute of the slaking. Preferably, the slaked lime is mixed with recirculated powdered lime from the flue gas cleaning before contacting it with the flue gases.

Abstract: A device for mixing particulate material and liquid includes a container, an inlet for the introduction of particulate material into the container, a liquid spraying device for spraying liquid over the particulate material in the container, a disc agitator arranged in the container, and an outlet for discharging material mixed with liquid from the container. A fluidization device is provided to fluidize the particulate material in the container during the mixing operation. The inlet is arranged at one lengthwise side wall of the container, so as to extend along that wall. The outlet is arranged in the other lengthwise side wall, so as to extend along the wall.

Abstract: A fan module for clean room applications, comprising outer, vertical restriction walls (5) with a lower edge part (6) having a planar lower surface (7) as well as an element (9) protruding from the outer edge of the planar lower surface for cooperation with a filter docking module (2) provided in a roof filter frame (4) having a substantially planar upper surface (8) with an extension corresponding to said planar lower surface, whereby said protruding element (9) is designed to overlap part of said filter docking module (2).