Process for producing cellulose derivatives of high bulk density, good flowability and improved dispersibility in cold water

A method of improving the flowability and/or the cold water dispersibility of a particulate cellulose derivative comprising the steps of

• A) providing a moist cellulose derivative having a moisture content of from 25 to 95 percent, based on the total weight of the moist cellulose derivative, with the proviso that no substantial amount of a surface-treatment additive is added to the cellulose derivative,
• B) grinding and partially drying the moist cellulose derivative in a gas-swept impact mill wherein a gas fed into the impact mill has a temperature of 100° C. or less;
• and
• C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill, wherein the additional amount of drying gas outside the gas-swept impact mill has a higher temperature than the gas fed into the impact mill.