A process is described for the continuous preparation and/or workup of polysaccharide derivatives by reaction and/or conditioning in a suspension with liquid reaction partners, in which, in accordance with FIG. 1, a) a preferably pumpable suspension stream of solids SE and liquid phase LE, if appropriate preheated to 185° C., is continuously introduced into the top region of a column, if appropriate under a pressure buffer of up to 6×106 Pa, which is virtually filled with the same liquid phase L, or another process-specific liquid phase L of preferably the same temperature, then b) the solids SE sediments freely due to the action of gravity through the liquid phase L to the column bottom, the solids SE converting to the solids SA by reaction and/or conditioning with the liquid phase L and c) possibly ascending gases G are discharged from the column via the column top and d) the solids SA is again continuously discharged as a suspension stream at the column bottom continuously by adding liquid phase LR taken off at the column top at a constant column filling level and transported in a separate connection, or liquid phase LN newly added from the outside to the column bottom.