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Historic tailings dams can often be considered as valuable mineral reserves due to the declining head grades of primary deposits. The reprocessing of such material is of great interest to the minerals processing industry, not only from an economic point of view, but also from an environmental one. However, tailings material is generally comprised of fine particles, which poses a challenge for its reprocessing using froth flotation due to reduced recoveries of these particle sizes. In addition, there is some debate as to the effect that these fine particles have on the froth stability, which in turn is linked to mineral recovery.In this work, air recovery was used as a measure of froth stability to determine the flotation response of a copper tailings ore to changes in particle size distribution and superficial gas velocity. The system exhibited a maximum in air recovery, which correlates well with the local peak in dynamic froth stability presented in previous work. This maximum in froth stability is also shown to correspond to an improvement in flotation performance, thus highlighting the importance of considering the link between particle size, air rate and froth stability when determining the flotation strategy for tailings reprocessing. The results are discussed in terms of the implications for the reprocessing plant from where the ore samples were obtained and, more generally, for the efficient flotation reprocessing of tailings.

Growth in length and weight of round whitefish was similar in two localities in Ungava, northern Quebec. The pattern of growth, however, differed from those reported previously for round whitefish from the Great Lakes. Round whitefish from Ungava are slow growing and approach their maximum size at a constant growth rate, whereas those from the Great Lakes approach their upper size limit rapidly within the first 3 years and thereafter growth is slow. The maturing age was greater for both Ungava males and females (4+ and 3+ years respectively for the earliest specimens) than for round whitefish from the Great Lakes. Though round whitefish are abundant in the Ungava region, they are of no commercial interest because of their slow growth and small average size.