Arsenic removal from contaminated soils for recycling via oil agglomerate flotation

Abstract

In this study, a flotation process is proposed for separating the arsenic-bearing minerals to recycle the soil surrounding the Janghang refinery in South Korea, which contains a high level of arsenic. To maximize the arsenic recovery, several experimental parameters were systematically investigated. X-ray diffraction revealed that the contaminated soil was mainly composed of arsenopyrite (FeAsS), arsenic trioxide (As4O6), arsenic pentoxide (As2O5), and quartz (SiO2). Flotation experiments with various concentrations of potassium amyl xanthate (PAX) showed that arsenic recovery increased with increasing PAX concentration. The addition of activators (Na2S, CuSO4, Na2S+CuSO4) in pulp pH greatly increased the arsenic recovery. In addition, oil agglomerate flotation was conducted to enhance the arsenic recovery by improving the separation of fine particles. The results showed that arsenic recovery increased with increasing nonpolar oil concentration. Based on the results obtained from the optimization tests, a flotation process by which the arsenic-contaminated soils can be recycled was successfully designed.