Preparation of these workshop lectures on the broad topic of ‘clay in oil sands’ was motivated by two observations. The first was the growing interest in the effects of clay on oil-sands operations, in particular bitumen flotation and fine-tailings management. The second was the lack of a common basis of understanding, or even common vocabulary, among the various disciplines involved in investigating and managing those effects. The hope is that the contributions herein will summarize current knowledge about the effects of clay on oil-sands operations, while gently introducing basic theory, terminology, and methods that the authors and editors believe will facilitate further advances.

Depending on the context and discipline, the terms ‘clays’ or ‘clay’ may be used in three different ways: as a particle-size term, as a mineral term, and as a rock term ( Moore, 1996 ). The field of oil-sands research makes no exception and various uses can be encountered in the literature, including terms such as ‘clay-sized minerals,’ ‘fine clays,’ ‘ultrafine clays’ (or ‘ultrafines’), ‘estuarine clay,’ ‘marine clay,’ etc. In this chapter, an overview is given of: (1) the nomenclature associated with clays and clay minerals; (2) the structure and crystal chemistry of phyllosilicates; and (3) the geology and clay mineralogy of oil sands.

The oil-sand ores of northern Alberta provide a significant proportion of the overall energy portfolio for North America. Surprisingly, the presence of nano-sized clay minerals plays a defining role both in the extraction of bitumen and in tailings management. Although seemingly insignificant in size, naturally occurring clay minerals present in the oil sand ores of northern Alberta create significant challenges in all aspects of bitumen extraction and recovery, processing of oil sand ores, and management of tailings. Although a significant body of knowledge exists in relation to the characterization of ‘oil-sands clay minerals,’ much of this work has focused on the identification of the clay minerals present and not on their respective surface chemistries. This chapter focuses on some of the unique structural features of the clay minerals found in the oil sands and their respective surface chemistries.

Slurry colloidal and particle interaction theory is described and applied to clay mineral suspensions. Mechanisms which affect the colloidal properties of the dewatering behaviour of clay mineral suspensions are described, after which the processes of coagulation and flocculation are discussed. Finally, sedimentation and self-weight consolidation are discussed as the mechanisms by which a low-density slurry transitions to a high-density slurry or soil.

With the myriad of measurement techniques and definitions of clays, the first question generally asked is “how much clay is there” in a sample? This often refers to the magnitude of a clay attribute in the sample and the answer to this question may vary depending on the measurement method. Does the method measure the clay-mineral type, the size distribution or mean size, the surface area, cation exchange capacity (CEC), rheology, or plasticity? Clay mineral type, particle size, and surface area are commonly used in mining operations to optimize oil-sand ore blending. In bitumen extraction and tailings management, where slurry behavior contributes to the process performance, propertiess uch as rheology and plasticity are also used. The previous chapters in the volume have introduced the various properties of clay particles and clay minerals. The present chapter describes the common methods of measuring clays and clay minerals in oil sands.