School of Civil, Environmental and Mining Engineering

Mining Engineering

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Optimisation

Mining engineering is applied to determine the best way in which to extract a mineral resource from the earth. Unlike most other engineering disciplines, mining engineering is driven by goals that are quite tangible, most notably to maximise value for shareholders. With a clear objective there is the ability to mathematic optimisation techniques, such as linear and integer programming and evolutionary algorithms, to help improve planning the extraction of these resources. The ability to use optimisation procedures to the mine engineering process enables a range of decisions to be considered simultaneously in attempting to find the best possible solution.

There is a relatively new area of research that focuses on including knowledge of the uncertainty inherent in all mining operations in the planning process, to achieve most robust solutions that will sustain a range of possible future outcomes.

At UWA, we are focusing on improving the flexibility and efficiency of optimisation formulations for both open pit and underground mines, in addition to exploring the new methodologies for including price and grade uncertainty which the optimisation framework.

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Simulation

Simulation is the act of imitating real systems with the objective of gathering knowledge ahead of time to provide more information for decision making. This field is particularly useful for mining operations in gaining an understanding of the utilisation of expensive equipment in the presence of queuing, failures, maintenance and start up times.

We have research projects focusing on the maximum production of a decline, appropriate planned maintenance strategies, and comparing truck requirements derived from simulation and from traditional static techniques.

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Underground backfill

There is increasing local and regional community support for the use of backfill in underground mining. This is due to increased extraction and the environmental benefits that accrue from reduced volumes of tailings stored on the surface.

Traditionally, backfill has been rockfill or hydraulic fill. Advancements have made the preparation, transport and placement of full plant tailings possible. This required that backfill be transported at relatively high solids contents to prevent segregation and separation, leading to the adoption of the term pastefill.

Technology gaps mean geotechnical risks cannot currently be adequately quantified. Concerns remain regarding issues relating to safety (particularly loads on barricades), production (fill mass failure) and costs (binder and additives).

This research has demonstrated that an effective stress approach, the cornerstone of traditional soil mechanics, is essential to addressing the above problems. New techniques have been developed for quantifying the strength and stiffness development within a cementing fill. Shortcomings in currently used procedures are being quantified through testing in the UWA geotechnical centrifuge.

A final outcome will be improved management procedures for utilising backfill and significant savings in cement used, without compromising on safety.

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The risk of progressive failure of pit slopes

Increasingly, large open pits are being developed in regions of the world where hard, competent bedrock only occurs at significant depth, with the upper profile being weathered to a marked degree. Conventional rock mechanics approaches to the stability of open pit slopes are inappropriate in these instances, and account must be taken of the potential breakdown of weakly cemented structure and resulting strain softening mechanisms in these applications.

The project is investigating ways of modelling strain softening and progressive failure using, among other theories, critical state soil mechanics. The intention is to ultimately produce guidelines on suggested shear strength tests to adequately determine design parameters for these applications.

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Appropriate cover systems for tailings storage facilities and waste rock dumps in the Australian climate

The approach to design of cover systems for mine waste storage facilities has often in the past been based on approaches developed in the northern hemisphere, where temperate climatic conditions prevail.

The mining industry in Australia has recognised the need to develop more appropriate designs for the hot and often very dry conditions that prevail at many mine sites. In parallel with these developments, the landfill industry in Australia has also begun to consider the need for more appropriate cover systems; this project, termed the Australian Alternative Covers Assessment Programme (A-ACAP) has seen the construction of five sets of field trials across the country.

The project is now into a phase of intensive data collection and interpretation, and the results of these experiments will be fed back into the design of future mining applications.

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Enhancing contaminant treatment with electrokinetics

In situ treatment of contaminants in the subsurface is often inefficient due to difficulties in achieving uniform contact between the treatment solution and the contaminant because treatment solutions cannot contact contaminants trapped in low permeability zones.

Very few large dense non-aqueous phase liquid (NAPL) contaminated sites have been restored to drinking water standards. Treatment of soil and groundwater contaminated with dense non-aqueous phase liquids such as trichloroethylene (TCE) is rendered ineffective by subsurface heterogeneity and complex NAPL architecture.

By combining broad electric field electrokinetics with nanoscale zero valent iron (nZVI), greater capabilities in the remediation of light and dense non-aqueous phase liquid contamination at large scale contaminated sites have been demonstrated. The use of nZVI induces both rapid and complete degradation of many organic contaminants when the nZVI is brought into contact with the contaminants.

The advantage of electrokinetic delivery is that the movement of nZVI through the media is largely independent of permeability. Both the rate of delivery and the uniformity of the delivery are orders of magnitude faster and more effective than achieved with physical flow alone.

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School of Civil, Environmental and Mining Engineering

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Last updated:
Monday, 10 March, 2014 10:58 AM

http://www.ceme.uwa.edu.au/411830