Abstract: A method and apparatus for deinking a fibre stock or slurry. In order to optimize the separation process the invention proposes to independently control the air injection phase, the mixing phase, and the separation phase by splitting them into separate steps.Thus, there is provided a separation cell which is fed with slurry from an inlet. Air is introduced into the slurry before entry into the separation cell and before entering a mixing section which mixes the air and slurry before entering the separation cell. The air is introduced under pressure by way of a porous sintered sleeve, while the mixing is achieved by the provision of three turbulence discs in the preferred embodiment. Alternative turbulent generating means may be employed.The mixing ensures contact of the ink with the air bubbles which separate out in the separation cell and rise to the surface as a foam. The foam is removed by suction, while the deinked fibre slurry is drawn off from the tank by means of a weir or stand pipe.

Abstract: A method for purifying a triazole composition is disclosed. The method involves the steps of producing a substantially anhydrous slurry in an alcohol of an alkali metal or of an alkaline earth metal salt of the triazole to be purified, separating solids from the slurry and washing the solids with an alcohol. A preferred method includes the steps of charging to a suitable vessel a crude triazole, a substantially equivalent amount of sodium hydroxide, added to an aqueous solution, hexanol or another alcohol having comparatively low water solubility, and xylene or another inert solvent; water is then removed from the system by azeotropic distillation to produce the desired slurry. When the triazole is benzotriazole or any given tolyltriazole isomer, the purified triazole can merely be recovered from the dried solvent system by filtration, washed (usually with a mixture of fresh solvent of the same identity as that from which it had been filtered) and dried.