Patent ID: 7001582

Claim:
A method for producing particulate barium sulfate in which at least 90% of the particles have a primary grain diameter of less than 0.1 μm, said method comprising: combining a barium salt solution with an alkali sulfate salt solution to form a reaction mixture in a continuously operating mixing reactor, in which shear, displacement and frictional forces of intermeshing tools act at high relative speed on the reaction mixture formed, wherein at least some of said intermeshing tools are mounted on at least one rotor which rotates at a rotational speed of from 2000 rpm to 8000, whereby resulting barium sulfate is precipitated, wherein a wetting agent or a dispersing agent is added during or after precipitation of the resulting barium sulfate and after passage of the reaction mixture through the reactor, separating and drying the resulting barium sulfate; wherein the concentration of barium salt and sulfate in the salt solutions is at least 80% of the maximum possible concentration.