Patent ID: 7501110

Claim:
Barium sulfate produced by a process wherein a barium salt solution and a sulfate solution are simultaneously and continuously brought together in equimolar quantities in a precipitating suspension at a temperature of 30 to 90° C., with constant stirring to produce at least one of lamellar barium sulfate particles or needle-shaped barium sulfate particles, wherein the precipitating suspension is withdrawn continuously in a steady volume and the barium sulfate precipitate is filtered, washed and optionally dried, wherein the barium salt solution has a concentration of 0.1 to 0.8 Ba 2+ mol/L and the sulfate solution comprises sulfuric acid in a concentration of 0.1 to 2.0 SO 4 2− mol/L and the flow rate and stirring speed are controlled, at a constant precipitation volume, in such a way chat a pH value of 1 to 9 is obtained in the precipitating suspension, wherein the lamellar particles are 1 to 50 μm wide, 1 to 50 μm long and 0.1 to 2 μm thick, and wherein the needle-shaped particles are 0.1 to 50 μm long and 0.1 to 2 μm thick, and wherein the ratio of length or width to the thickness is from 3:1 to 500:1.