The improvement in whiteness index of calcite tailings using attrition-scrubbing process.

Calcium carbonate (CaCO₃) is an essential mineral critical for various applications in many industries like plastic, rubber, paint, and paper manufacturing. However, salable CaCO₃ products need to meet specific requirements. For the paint and paper manufacturing industries, the whiteness index (WI) of CaCO₃ is an important property because it strongly influences the final color of paper and paint products. In this study, the effects of retention time and pulp density on the WI after attrition-scrubbing of calcite tailings were investigated. To increase the whiteness index, an attrition scrubber was used to remove impurities on the CaCO₃ surface with different pulp densities—40, 45, 50, 55, 60, and 70% solids—and retention time—10, 15, 20, and 25 min—as process variables. The results of laboratory-scale experiments found that the attrition-scrubbing process improved the whiteness index of CaCO₃ tailings and reduced its iron content. The optimum condition was at the pulp density of 55% solids, which was used in the pilot-scale experiments. The results of the pilot-scale tests were consistent with the laboratory-scale, indicating that the attrition-scrubbing process can be used to improve the quality of CaCO₃ tailings. [ABSTRACT FROM AUTHOR]