CONTINUOUS SYNTHESIS OF CHROMIUM DIOXIDE

摘要

A continuous chromium dioxide synthesis process consists essentially of feeding through an extruder screw (14) while preheating, to just below the temperature at which incipient reaction occurs, a viscous paste mixture comprising CrO3, Cr2O3 and H2O at elevated pressure to a reaction zone in the form of a twin-screw reactor (15); advancing the paste mixture in a starved (nonflooded) mode through the reactor (15), at elevated temperatures and pressures, the residence time being sufficient for the paste mixture to react to form CrO2; continuously venting byproduct oxygen and steam (34), thereafter injecting water (40) at high pressures into the reaction product to form a viscous CrO2-H2O slurry, and discharging the slurry from the reactor (15) into a separate pressure let down zone (48), wherein the slurry is cooled and depressurized to atmospheric pressure.