Whitening of calcium carbonate tailings using attrition process: a case study of Khar Toum deposit, Lopburi province, Thailand

Abstract

Calcium carbonate (CaCO3) is one of the industrial minerals that usually use in various applications in many industries (e.g., plastic, rubber, paint, paper). However, salable CaCO3 products need to meet the requirement for each application. Whiteness is one of property that really important especially the application that concern about the color like paint and paper industries. In this study, to recover and utilize out of spec ores, the effects of attrition scrubbing process (i.e., retention time and solid in pulp) on the whiteness of the CaCO3 tailings were investigated. The CaCO3 samples were screened to obtain –300, +300–600, +600–1000, +1000–2360, +2360–4000, and +4000 µm size fractions. From the material characterization, the fine particles (–300 µm) showed the lowest whiteness index (i.e., < 80%) while other size fractions were higher (i.e., > 80%). To increase the whiteness index, attrition scrubber was applied to remove the impurities on the CaCO3 surface with difference solid percentage (i.e., 40, 45, 50, 55, 60, and 70%) and retention time (i.e., 10, 15, 20, and 25 min) as condition. The result in laboratory-scale found that the attrition scrubbing method can improve whiteness property and reduce iron content in calcium carbonate tailing. The optimum condition was at 55 solid percentage which was used in the pilot-scale experiment. The result was in line with the laboratory-scale, the whiteness was improved to meet the market standard. Therefore, the attrition scrubbing process can be used to improve the quality of calcium carbonate tailing.