Role of Surfactants in Reducing the Ground Quartz Contamination by Iron

Abstract Iron contamination of ground material is unavoidable in conventional steel grinding mills, particularly when processing hard minerals like quartz. This contamination negatively impacts industrial applications requiring high purity and whiteness, as well as complicating separation processes for many minerals. Numerous studies have explored ways to reduce this contamination, either by using alternative mill types or grinding with high-chrome steel balls. However, no studies have investigated—or even attempted to investigate—how to mitigate such contamination in conventional steel mills. This study examines the extent of iron contamination in quartz when ground in a conventional ball mill and its subsequent effect on the grinding process. The degree of contamination was first assessed in different mill types (ceramic vs. steel ball mills). Additionally, grinding was conducted in the presence of two chemical reagents—sodium dodecyl sulfonate (SDS) and quaternary amine (QA)—which differ in their affinity for quartz, to evaluate their effects on iron contamination levels. The results showed that the change in color (used as a contamination indicator) varied depending on the reagent used, a finding further supported by XRF analysis. SDS proved more effective at reducing contamination due to its interaction (neutralization) with iron, preventing its adsorption onto quartz. The whiteness of the SDS-treated sample (40%) is more closer than other ground samples to the whiteness of ceramic-milled quartz (72.5%), which reduce contamination. Furthermore, the influence of contamination on quartz dispersion or settling behavior in the presence of these reagents helped explain the grinding results, particularly in terms of the ground quartz’s d 50 .