Diagnosis of the Surface Chemistry Effects on Fine Coal Flotation Using Saline Water

In the present investigation, two coal samples were obtained from a typical Australian coal flotation plant using saline water and examined to identify surface chemistry effects on fine coal flotation which is an important issue confronting the coal industry. The speciation modeling indicated that hydrophilic precipitates may occur in the flotation circuits as a result of the use of high ionic strength water, negatively impacting the coal flotation. Meanwhile, Cryo-SEM (scanning electron microscopy) detected the presence of clay minerals on the coal surface which has a deleterious effect on the flotation. Surface oxidation was also found on both coal samples by XPS (X-ray photoelectron spectroscopy) analysis and well correlated with their flotation behavior. This study suggests mitigating the slime coating and addressing the oxidized coal surface simultaneously to improve the coal flotation.