Process and device for liquid withdrawal from particle-laden liquids, in particular for dewatering suspensions or sludges and use of the process

摘要

Previous processes for sedimentation of suspensions or sludges which contain magnetisable particles only utilise the gravitational forces and therefore work relatively slowly with low sediment densities. The sedimentation time is to be decreased and the sediment density increased by means of the novel process. The particle-laden liquid is introduced on a feed side into a sedimentation chamber (5.1), at least one expansion direction of the sedimentation chamber agreeing with the desired sedimentation direction (16a) of the particles. The volume of liquid contained in the chamber, apart from the gravitational field, is exposed to a strong magnetic field gradient, the force vectors and field gradients of which run in or substantially in the sedimentation direction (16a), so that the magnetisable particles are driven in the direction of increasing magnetic field strength and are compressed to form a sediment cake (10). The device for carrying out the process is provided with a vessel (70) for the sedimentation chamber (51), surrounded by at least one solenoid (100) of a superconducting magnet (SLM) and including a feed chamber (23) for the suspension and a discharge zone (230) for the sediment having a conveying element (26), and in addition a take-off orifice (27.1) for the settling liquid. The use relates to the sedimentation of iron hydroxide or iron-hydroxide-containing heavy metal hydroxides.