PROCESS OF ENHANCED PREPARATION OF BISMUTH-VANADATE COMPOUNDS

摘要

A process for improving the production of bismuth vanadate compounds of formula (B1a, IV), D (O) 4, wherein A is an alkaline earth metal, zinc or a mixture thereof, D is molybdenum, tungsten or a mixture thereof, and molar is described. the ratio of A to bismuth is between 0.03 and 0.4 and the molar ratio D to vanadium is between 0.01 and 0.3, as well as the solid solutions based thereon, and mixing with the subsequent precipitation of the bismuth salt solution containing the alkaline earth salt or a zinc salt or a mixture thereof, with an aqueous vanadate salt solution containing molybdate or tungstate salt, or a mixture thereof, as appropriate, in the above molar ratios, and b / subsequent crystallization and aging of the particles initially precipitated in the amorphous form from the obtained suspension, whereas, during the mixing and / or subsequent crystallization step, fluoride ions are used in an amount of 0.1 to 3 moles per mole of bismuth. The pigments produced in this way are distinguished by their particularly high dyeing and covering power