| abstract |
Apparatus for contacting solid particles with a liquid in a vessel having an agitator within a vertical draft tube, for instance for dissolving phosphate rock particles in acid, is characterised by means for supplying fluid under pressure to a bottom portion of the vessel to prevent solids settling and to resuspend solids that have settled, e.g. after shutdown. Apparatus for similar purposes is disclosed having a vent for minimising foaming. Also disclosed is a method of start up a continuous phosphoric acid production process in a multi-vessel system comprising four vessels (2), (16), (28) and (48). <IMAGE> |