GB995764A - Process for the separation of aqueous suspensions of carbon black - Google Patents

Abstract

Carbon-black is removed from an aqueous suspension thereof by mixing said suspension with a water-immiscible auxiliary liquid to form an aqueous phase and a mixture of carbon black and auxiliary liquid, passing at least the aqueous phase through a collecting vessel through which are also passed agglomerates of carbon black and the water-immiscible liquid such as to build up a layer of agglomerates which is at least partly flowed through by the aqueous phase, and removing from said vessel agglomerates, substantially separated from the aqueous phase, at approximately the same level as the discharge from the vessel of the aqueous phase. It is preferred that the aqueous phase and the agglomerates be continuously passed through the collecting vessel and that the liquid level in said vessel be kept constant. Agglomerates of carbon-black and a hydrocarbon or hydrocarbon fraction boiling at 190 DEG to 340 DEG C. are very suitable and it is preferred to employ agglomerates prepared from the original carbon black suspension. The collecting vessel may be a vertical vessel having the bottom, or parts thereof, or part of the side wall permeable to water but not to the agglomerates and this permeable section may consist, for example, of porous or perforated material. If the side wall is permeable the vertical extent of the permeable section should be such that water leaving the vessel passes through at least part of the agglomerate layer and said agglomerates may be removed by employing a riser which opens into the vessel at about the level of the permeable section. If the bottom is permeable it should preferably be flat and slope towards the agglomerate discharge line at an angle of not more than 15 degrees and it may be of advantage to shake the vessel or the bottom or part thereof. The vessel may also be provided with one or more collecting compartments, connected to the vertical vessel via the permeable sections, and a conveyer belt, permeable to water but not to agglomerates, connected to the agglomerate discharge line. Three apparatuses for performing the process of the invention are described. Reference has been directed by the Comptroller to Specifications 834,940, 834,989 and 846,219.