This thesis deals with the flow mechanics of hydraulic and high density mine backfill slurries in pipelines. Various empirical, rheological and mechanistic approaches are presented and analysed along with some aspects pertinent to experimental testing of backfill slurries.; The main contribution of this work is, particularly, in the development of an analytical model to describe the flow and predict the pressure gradient of a class of high density backfill whose motion in pipelines follows the Plug Flow Model (PFM). The development of the model called for investigating the conditions required for establishing Plug Flow. It was found that mix proportioning procedures, similar to those found in the concrete industry, are key factors in obtaining Plug Flow.; Pressure drop was found to be a function of the thickness of the Bingham plastic annular layer surrounding the cylindrical core of aggregates. Analytical equations were proposed to solve for the thickness of this layer by considering the rheology of the mixture. Alternatively, the thickness of the annular layer may be estimated by considering the relative proportions of the mixture with respect to aggregates void content. The model offered pressure drop predictions in good agreement with published data. The proposed model may also serve as an alternative to Mooney's method, when dealing with the annular lubricating layer effect characterising mixtures in Plug Flow.
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