The processing of oil sands results in the production and storage of significant amounts of waste materials, including: large volumes affine tailings from the separation of bitumen from oil sands and petroleum coke produced during the bitumen upgrading process. In several previous investigations we explored the production of potentially marketable products from these wastes. This paper is a review of work from the authors' laboratory. Several case studies illustrate the potential uses for coke and value added products separated from fine tailings.
Delayed and fluid coke from bitumen upgrading are effective sorbents for both bitumen and naphtha. They are also excellent collectors for heavy metals. Based on these properties and a plentiful supply at relatively low cost, these materials provide an excellent medium for treating oil-in water emulsions, for adsorbing oil spills for heavy metal trapping in the purification of industrial effluents, for the treatment of oily waters, for extracting hydrocarbons from ground water and/or the removal of odors.
Our work relating to the incorporation, or coating, of coke particles with lime or limestone is beneficial in the use of this material as an ancillary fuel with much reduced sulphur dioxide emissions. The ash from the combustion of coke can be leached to separate heavy metals. The leached residue could have potential applications as a flocculant for the treatment of fine tailings and possibly for the remediation of acid mine drainage.
The fine tailings are separable into several potentially valuable by-products such as: bitumen for production of synthetic crude oil or as an ancillary fuel, clean kaolin for fine paper coating, a gelling agent, emulsifying solids for surfactant replacement and a mineral fraction rich in heavy metals.
The production of refinery grade oil from the Alberta oil sands deposits as currently practiced by Syncrude and Suncor, generates a substantial amount of waste including, coke, fly ash, coarse sand and fine tailings. Under current production conditions, a plant producing 15,900m3/day (100,000 bbl/day) of synthetic crude oil requires the processing of 100,000 m3/day ore which results in a tailings stream consisting of 100,000 m3 of coarse sand, 2,000 m3 of coke, 100 m3 of fly ash and 20,000 m3 of Mature Fine Tailings (30% solids)1–2. As a result, a large inventory of process-affected materials are accumulating. The major concern regarding these wastes is a question of the volumes involved and the lack of an acceptable reclamation option.
The recognition and exploitation of the useful intrinsic properties of waste materials are becoming more important owing to increasing awareness of environmental issues. However, the commercial recycling of oil sands industry wastes has been limited to the use of sulphur and the burning of small amounts of coke. Recently, however, there has been extensive investigation of heavy metal recovery from centrifuge rejects and aluminum production from clay3. It is anticipated that high disposal costs and increased regulatory pressures to minimize landfill disposal options will increase the incentives for recycling by-products from these oil sands industry wastes.
For the past several years, we have been developing separation techniques for the recovery of by-products from oil sands industry wastes4–10.
