Abstract: Hydrocyclone apparatus having means for controlling the gravity of the discharging underflow. The means consists of a plurality of sectors formed of resilient material which are mounted below the apex opening of the hydrocyclone whereby when relaxed the apexes of the sectors terminate at the hydrocyclone axis and the side edges of each sector are in juxtaposition with adjacent sectors. When the hydrocyclone is in operation the discharging underflow material deflects the sectors downwardly and so controls the underflow as to maintain its density substantially constant irrespective of changes in the density of the slurry supplied to the inlet. Preferably the construction is such that an underflow shield is provided about the lower end of the hydrocyclone apex. The invention also includes the method employed by use of the apparatus.

Abstract: A flat spray nozzle head for a manually-operated spray gun for spraying a material, such as a color material or the like without compressed air, comprising a nozzle portion containing a nozzle body arranged therein and a connection portion for connection with a spray pump for spraying the material to be applied. An infeed element for the infeed of the sprayed material to the nozzle body is arranged within the nozzle portion. This infeed element is rotatably mounted in the connection portion. The nozzle portion is thereby rotatably connected with the connection portion.

Abstract: A method of removing fly ash particulates suspended in industrial waste gases generated from the combustion of fossil fuels in a totally enclosed scrubbing liquor circuit whereby an inert diluent such as Na.sub.2 SO.sub.4 is used for inhibiting the dissolution rates of the alkaline earth, silica, and clay mineral ingredients in the ash when the collected particulates are intermixed and suspended in weak acid solutions produced in the wet scrubbing process. The diluent may be added to the system or, if the waste gas contains significant amounts of sulfur oxides, it may be formed in situ.