Grants and Contributions:
Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)
The difficulty of mineral separation sharply increases as the particle size of the processed minerals decreases. Similarly, subsequent stages of solid-liquid separation also suffer as the sizes of the treated particles decrease. As a result, separation and recycling of water from fine mineral particles remains a major problem in such fine particle systems. As presently-mined ores often require ultra-fine grinding for efficient separation, it appears that the industry will have to develop new approaches to deal with the increasing amounts of fine particles.
The overall objectives of the proposed research program are aimed at enhancing our ability to deal with these processing issues, and whether polymers can better be utilized to overcome such particle size-related separability limits. The effect of polymer adsorption, whether physical or chemical, on the properties of interparticle structures will be determined. A need also arises to adapt and develop new testing methodologies to obtain information about the micro- and macro-properties of fine particulate systems. The lack of appropriate in-situ testing methods is largely responsible for our inability to look inside sediment structures, and how those structures respond to various treatments. In a novel application, the experimental program will involve x-ray computed tomography (CT) for visualizing and analyzing internal structures of sediments, and how the sediment structure changes under pressure during solid-liquid separation. Changes in sediment properties as a function of time can also be monitored using laser light back-scattering. The back-scattering method allows estimation of the solids content to be made along the sediment height. The surface charging characteristics of particles/flocs in sediments will be probed with the streaming potential method. The resistance of sediments to external forces and the amount of water released by the sediments will be researched through compressive rheology, which in combination with the CT results should provide a new insight into the dewatering behavior of flocculated mineral suspensions. The tested polymers will be characterized using ultracentrifuging and viscosity techniques. It is envisaged that all the work will be performed using a range of different polymer-mineral systems, under various pH and ionic strength conditions.
The mineral processing industry often comes under scrutiny for the environmental impact of tailings facilities, and for the less-than-optimal water recycling practices. Nevertheless, water will still be the process medium in the foreseeable future for all technologies used for separation of fine mineral particles. It is believed that the results of this program will contribute to smarter and more efficient approaches to water utilization. The data should also be applicable to other industries using polymers and handling solid-liquid suspensions.