PRODUCTION OF BARIUM SULFATE WITH CONSIDERABLY IMPROVED WHITENESS THROUGH CALCINATION OF BARITE RECOVERED FROM WASTE MATERIAL

The study presents calcination of barite recovered from the gangue stored in the tailings dam at a metallurgical plant in Bulgaria with the aim to product BaSO4 with improved whiteness. The calcination was carried out in a rotary kiln at 1150⁰C under air. Samples from three batches of barite with different particle size, namely 40 µm, 20 µm and 6 µm, were processed and the color and brightness value of the product was measured. The residence time of the material in the kiln, respectively in the heated zone, was also determined. The results show that the brightness of the barite recovered from the gangue could be improved by 4 – 20 units through calcination.