Abstract: An electrostatic filter for the separation of particles includes a particle charging unit arranged upstream, includes at least one corona wire for the charging of particles and a particle collector unit arranged downstream relative to it. The particle collecting unit includes two groups of plate-like elements (1, 1′) arranged essentially parallel between each other and the flow direction through the device at a predetermined distance from each other, wherein a first group of elements (1) is connected to earth (3) and a second group of elements (1′) is electrically insulated with reference to the device and to the first group of elements (1) and that the elements (1, 1′) essentially are made of one or more non-hygroscopic polymer materials with a mass resistivity which preferably lies within the region of 1×102 &OHgr;cm to 1×108 &OHgr;cm.

Abstract: An electrostatic filter for the separation of particles includes a particle charging unit arranged upstream, including at least one corona wire for the charging of particles and a particle collector unit arranged downstream relative to it. The particles collecting unit includes two groups of plate-like elements (1, 1') arranged essentially parallel between each other and the flow direction through the device at a predetermined distance from each other, wherein a first group of elements (1)is connected to earth (3) and a second group elements (1') is electrically insulated with reference to the device and to the first group of elements (1) and that the elements (1, 1') essentially are made of one or more non-hygroscopic polymer materials with a mass resistivity which preferably lies within the region of 1.times.10.sup.2 .OMEGA.cm to 1.times.10.sup.8 .OMEGA.cm.

Abstract: A method and a d.c. arc furnace for thermal treatment of an ash, wherein reducing conditions are established within a closed and sealed furnace, the ash is supplied via a channel arranged in an electrode which extends towards a metal melt in a furnace shell and provides an arc extending toward the metal melt, the ash being fed from the open free end of the electrode through the arc, any slag and/or the metal melt, whereby the ash is rapidly heated under reducing conditions to a temperature of 1350.degree. C. to 1750.degree. C.

Abstract: In a method for cooling a rotary kiln having a cylindrical outer jacket, cooling air is blown at high speed radially towards the jacket from an annular supply-air chamber surrounding the jacket and having a perforated inner wall which is located at a slight distance from the jacket and through which the cooling air is blown towards the jacket. The cooling air is sucked out from the space between the jacket and the inner wall to an annular exhaust-air chamber which is separate from and surrounds the supply-air chamber and communicates with said space. The cooling-air flow through the chambers is adjusted by fan devices connected thereto. A device for implementing this method has an annular supply-air chamber surrounding the jacket and having a perforated inner wall which is located at a slight distance from the jacket and designed for radially blowing cooling air towards the jacket.