This report evaluates the potential of metakaolin recuperated from oil sands tailing ponds in North Alberta as a supplementary cementing material -SCM- for concrete. Oil sands operations produce vast quantities of tailings containing extremely fine clays that prevent the reuse of process water from the tailings ponds. Preliminary research has indicated that this fine material can be processed into a product similar to metakaolin -MK- . Metakaolin is a valuable product with many commercial uses including as a high performance SCM. Extracting the fine clay from the ponds to produce SCM would have two benefits: clarifying the process water for reuse in the operations while producing a valuable product from a by-product.
The study finds however that while it is technically feasible the concept is uneconomical for many reasons. The material that can be produced from the pond â€“ called calcined mature fine tailings or CMFT â€“ while similar to MK has lower quality and performance than the products currently on the market. Another shortcoming is that CMFT is grey while metakaolin from virgin kaolin is white. Therefore in performance and appearance CMFT cannot compare to MK. Rather it is more like fly ash -FA- another SCM abundantly available in Alberta but at a much lower price than MK. Furthermore the oil sand region is isolated landlocked and far from the market for concrete. Because of the cost of extracting drying calcining and transporting the material CMFT cannot compete against FA and the study concludes on the non-feasibility of the concept. The oil sand industry still wants to resolve its water and pond issues and continues to investigate ways to process the fine tailing. If this research is successful and CMFT with improved quality color and cost can be produced then it will be worthwhile to reexamine the case and see if the product can be used in concrete.
Technical Report Author: EcoSmart Concrete Project