Perspectives on development of nanofibrillated cellulose for mine waste tailings management

Abstract There is a huge inventory of fine tailings from mining operations in tailings storage facilities (TSFs) awaiting remediation operations. Returning TSFs to their original states as dryland is the preferred closure action and chemical additives are used in the necessary thickening (dewatering) step of the fine tailings. Synthetic fossil fuel-based polymers known as flocculants are used in the dewatering process industrially. Nanofibrillated cellulose (NFC) is a biomass-derived product which can be developed to substitute the prevailing synthetic flocculants. This review describes the pertinent subjects related to the extraction of NFC, chemical modification, their physical and chemical characterization and evaluations as flocculants. NFC has been separated from biomass by physical, biological, and chemical processes, including combinations thereof. Properties which flocculants possess that pristine NFC lacks are mainly incorporated by chemical modifications. Chemical modifications take place via the hydroxyl groups that surround the polysaccharide skeletal structure of NFC. Prospective chemical modification reactions to produce effective flocculants are discussed. Other properties that can fine tune flocculation performance of NFC such as charge type, density, and size are also covered. The preparation of new, modified-NFC flocculants needs to include characterizations to provide detailed information about flocculants’ particle dimensions, morphology, surface charge, surface chemistry, crystallinity, and flocculant rheological properties. Methods to evaluate the flocculation performances and the resulting deposits of modified NFC treated geotechnical properties are presented to wrap the review. The results of such a study will enable correlation of modified-NFCs with their efficacy in the treatment of mine waste fine tailings.