Paste technology is a unique way of disposing of mine tailings. Paste tailings are essentially dewatered mine tailings that form a dense, viscous mixture, which unlike a conventional tailings slurry, do not segregate during mixing and transport. This thesis investigated three characteristics of paste tailings; namely, beach slope, drying behaviour and liquefaction potential.
Once paste is deposited into a tailings impoundment and has settled, it will sit at its natural beaching slope. It is important to know what angle the paste will beach at when designing the size of a tailings impoundment. In order to avoid expensive field trials, a laboratory test that would accurately predict the beaching slope of paste tailings was required. Investigating such a test was an aim of this thesis.
Exposure of a paste tailings deposit to sun drying causes desiccation, which is essential to increase consolidation. The resulting strength gain leads to improved stability of the paste tailings deposit. When the next layer of wet paste is deposited over the dry paste, some rewetting of the dry paste may occur. This can cause swelling and loss of strength of the deposit. In this thesis, a controlled experiment was performed, which determined the degree of rewetting that a dry layer experienced due to the addition of a wet layer of paste.
A soil-like material will liquefy when four conditions occur; namely, the material is fine sand-sized, it is saturated, it is loosely-packed, and there is a sufficient dynamic disturbing force such as an earthquake. Upon liquefaction, particles become surrounded by water and the material loses strength. Previous research has suggested that due to the inherent properties of paste, it will not liquefy. However, no experimentation had been performed to validate this hypothesis. In this thesis, paste tailings were exposed to a simulated earthquake loading on a laboratory shaking table and their behaviour recorded.