Study of the Rag Layer: Characterization of Solids

Abstract

During separation of emulsified water from oil, a viscous intermediate layer builds up between water and oil phases. This layer which is referred to as rag layer disrupts emulsion destabilization and water removal. The present research is intended to better understand the formation of a rag layer and its properties, so that rag layer formation can be prevented. Two industrial froth samples are considered: one readily forms a rag layer and the other does not. Characterization of emulsion and contained solids is completed to elucidate the key properties that result in rag layer formation. Key differences between the solids that formed and did not form rag layer were identified as: (i) organic contaminates of rag-forming-solids contain more aromatic compounds as compared with those of the non-rag-forming solids; and (ii) rag-forming solids are more hydrophobic. Moreover, mineralogy analysis of these two solids showed that rag-forming-solids contain a considerable amount of iron-based minerals, such as siderite and pyrite. Such research has provides a better understanding of these complicated, troublesome systems.