In a vehicle having an engine which derives power from a reaction of NaK and water in the presence of air, NaK hydroxide is a reaction product in the form of particulates suspended in an exhaust gas consisting principally of nitrogen with some water vapor. In order to release the exhaust as a harmless gas to the atmosphere and to retain the NaK hydroxide in the vehicle for removal during a fuel stop and subsequent reduction back to NaK metal, several stages of separation of the particulates from the gas are provided. A first stage, preferably based upon impingement of the NaK hydroxide particulates on a molten NaK hydroxide surface, separates a substantial portion of the particulates. A final stage of separation comprises filtration wherein two filters are used alternately, one filter separating the water soluble NaK hydroxide particulates from the exhaust gas while the other filter is being flushed with water as a solvent to dissolve accumulated NaK hydroxide thereby regenerating the filter. The flushing water which contains the dissolved NaK hydroxide is returned to a reservoir which also provides the water for the reaction of NaK and water. The functions of storing a reactant for combustion and of storing a solvent for dissolving accumulated particulates are both provided by a single body of liquid to result in a more simple structure and in less weight than would be feasible if separate reservoirs were used for the reactant and for the solvent.

A granular bed filter device comprising two gas-permeable walls bounding an annular filter bed disposed in a housing. The walls extend downwardly in a taper together and are inclined upwardly toward the central axis of the filter bed. A nozzle tube projects from above into the housing and has nozzles which are directed against the inner wall of the filter bed. In order to regenerate the dust-laden filter bed, compressed air is blown intermittently through the nozzle tube while at the same time the nozzle tube is set in motion by a motor. The accumulations of dust contained in the filter bed are ejected in agglomerated form through the outer wall and fall down into the region of a discharging conveyor.

A mass-transfer column consisting of one or more contact zones. The contact zones are exclusively provided with packings placed in prearranged locations. In the contact zones, optimal operating conditions for the packings are created over the entire height of the contact zones in order to achieve a minimal pressure loss at a concomitant high separating efficiency. This is done by implementing a suitable gradated adaptability of the packing to the vapor and liquid loads varying over the height of the contact zones.

An air pollution prevention device that is designed in the preferred embodiment to operate downstream from an existing muffler. The device comprises an oil filled lower chamber with turbulence causing means such as plastic netting through which the exhaust gasses pass. Two upper chambers having turbulence causing means such as steel wool receive the gasses and oil from the lower chamber. The particulate matter in the gasses is coated with oil and being heavier than the exhaust gas will drop out of the exhaust gas and run into the lower oil chamber where it can be periodically removed along with the oil when clean oil is added to the device.

A fluidized bed plate has been provided which provides uniform flow of a sodium-gold-cyanide or sodium-silver-cyanide solution in gold and/or silver recovery by means of sorbing or desorbing in a fluidized carbon bed. The bed plate comprises a floor grate which supports a screen mesh which in turn supports one or more layers of shot. Carbon particles are supported by the shot. The flow of the fluid is uniform through the mesh and shot because of the arrangement of the voids created between the shot due to their natural stacking characteristics. This fluid flow is effective in fluidizing the carbon particles uniformly with little abrasion. A unique tank design permits desportion of the carbon particles while the tank is temporarily taken off-line. After the tank is reactivated it can be placed back on-line as required. The fluidized bed plate of this invention can be used in a column where processing of the solution in series is desired.