SEMINAR: ANZIAMWA seminar
|ANZIAMWA seminar : Two examples of geotechnical modelling: cemented paste backfill in underground mines, and predicting beach slopes in tailings deposits.
Disposal of mining waste is becoming one of the key issues holding up permitting of some new mines; it contributes to the ‘social licence to operate’, a term that is used to characterise the concerns and resistance to mining from communities potentially affected by the mining process.
The largest volumes of mining waste are often the tailings (crushed and processed ore), which are usually in a fluid state when pumped to the tailings storage facilities (TSFs). Failures of these facilities occur with monotonous regularity, plus many of them adversely impact the surrounding environment. Two methods of reducing this impact are discussed, and modelling requirements explained.
The first topic deals with the placement of tailings back into the underground voids formed by mining, after adding small amounts of cement. This cemented paste backfill (CPB) hydrates and gains strength over time. The rate of gain of strength and stiffness, the amount of consolidation, and interaction with the adjacent rock mass are all components that require modelling. A particular topic that has been highlighted as contributing to the successful use of CPB is termed ‘self-desiccation’, which is the volume loss during the hydration process. This process and its impacts on stability of the CPB system are described.
The second half of the talk focusses on the placement on surface of tailings that have been dewatered to an extent not previously possible, producing what is termed thickened tailings or paste tailings. When this non-Newtonian material is deposited from a pipeline, it forms a positive gradient as it flows on the natural ground. The slope of this ‘beach’ is a key input to design of these facilities, but to date the techniques used for predicting these ‘beach’ slopes are mainly empirical and not well proven. The techniques used to characterise these materials and some examples of their application are described, followed by a brief discussion of currently used methods for beach slope prediction and the need for development of a method based on fundamental understanding of the relevant processes.
Maths Lecture Room 2
: 6488 3355
Tue, 09 Apr 2013 18:00
Tue, 09 Apr 2013 20:00
Tania Blackwell <[email protected]>
Fri, 05 Apr 2013 12:07
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