| US 7,501,110 B2 | ||
| Process for producing barium sulfate, barium sulfate and use thereof | ||
| Djamschid Amirzadeh-Asl, Moers (Germany); Jürgen Bäuml, Kamp-Lintfort (Germany); and Udo Selter, Moers (Germany) | ||
| Assigned to Sachtleben Chemie GmbH, Duisburg (Germany) | ||
| Filed on Mar. 11, 2005, as Appl. No. 11/77,775. | ||
| Application 11/077775 is a continuation of application No. 10/009099, abandoned, previously published as PCT/EP00/02872, filed on Mar. 31, 2000. | ||
| Claims priority of application No. 199 26 216 (GE), filed on Jun. 09, 1999. | ||
| Prior Publication US 2005/0180912 A1, Aug. 18, 2005 | ||
| Int. Cl. C01F 5/42 (2006.01) | ||
| U.S. Cl. 423—544 [423/160; 423/161; 423/166] | 9 Claims |
| 1. 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of lamellar barium sulfate particles or needle-shaped barium sulfate particles, wherein the precipitating suspension is withdrawn continuously in a steady volume and the barium sulfate precipitate is filtered, washed and optionally dried, wherein the barium salt solution has a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 Ba2+ mol/L and the sulfate solution comprises sulfuric acid in a concentration of 0.1 to 2.0 SO42− 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. |