Preparation of non-ferrous metal ore containing sludges with EVACTHERM~reg; drying technology

摘要

The EVACTHERM~® vacuum drying process with superheated steam in an Eirich mixing reactor has repeatedly proven in operation under industrial conditions; this process enables the preparation without any problems of - for example - galvanic sludges and metallic hydroxide sludges from waste incineration plants into dustfree granules without preconditioning. Drying is made by introduction of superheated steam in a mechanically generated fluid-bed. Cooling is made by pressure reduction to 80 mbar absolute by using the vaporizing of water. Due to the preparation under slight subatmospheric pressure and the mode of operation in closed circuit of the drying medium superheated steam, drying and granulation is realized under inert conditions without odorous gas emission and at minimum energy consumption. Changing starting conditions and varying raw material characteristics can be balanced without any problems during the discontinuous drying process by adaptation of process times and process parameters. With a mixing reactor volume of up to 7000 1 it is possible to achieve water evaporation rates of up to 2500 kg/h.