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By Ken MacLeod

A development at 83 Queens Road in Melbourne, Australia required construction of a three level basement. The normal geotechnical constraints of excavating adjacent to an existing relatively new building were challenging enough for the complicated soils profile occurring at the site. An additional significant challenge faced by the designers, was the requirement to excavate underneath the entire footprint of an existing heritage listed building, known locally as the Mansion, in the centre of the site. Maintaining the structural integrity of that building was afforded the highest priority during the 10m excavation. This paper describes geotechnical aspects of the analysis, design and construction of the secant retention system adjacent the new building and support of the Mansion enabling the 10m excavation to proceed without causing damage to the structure. The secant wall comprised hard-soft interlocking piles constructed using CFA methods. CFA piles along the length of the Mansion provided short term support, with the building load being transferred to the piles by large steel beams jacked under the building. Survey results confirmed that movements of the retaining wall and also the load bearing piles were minimal and well within design expectations.

Jan 1, 2006

By C. A. Brown

"Steady-state simulation has been used for over 20 years to optimise the operation of crushing and grinding circuits. Throughout that period continuing comminution research has been the basis for improving the models.Site surveys, ore characterisation, model development and investigation of different operating scenarios by simulation has proved to be a cost-effective method for improving plant performance. In this sense, this paper presents findings from experience with these valuable optimisation techniques with reference to specific case studies."

Sep 12, 2005

By Silvana Costa

Rapid changes in technology and human resources trends require the mining industry to plan carefully for new work camps. The abandonment of the “mining town” concept and rapid increases in the adoption of long distance commuting have intensified the need for improved planning and monitoring of existing and upcoming operations. New mines will have an increasing Aboriginal participation in their workforce and will mostly to be located in remote and in extreme weather conditions. In this sense, the intensification of the use of the commuting system has increased the need for improved planning and monitoring of upcoming operations. Given that mining development is experiencing a surge in activity in Canada, particularly in remote and northern locations significant number of individuals will get jobs that involve mine camp communities. Some employees will spend half of their working lives at the mine site for a period of time that can last up to 30 years. Even though investments have been made towards particularly high quality physical environments, mine camp policies, programs and employee quality of life in mine camps have not been studied in any depth.

Sep 12, 2005

By Terry A. Lee

The grade of mineral resource estimates underpin all major economic considerations of mining prospects. While there are reporting requirements to satisfy when stating a mineral resource estimate, an examination of NI 43-101 style reports suggests that authors believe that there are a number of ways of addressing these requirements. As a reader of these reports, some processes are helpful and others are not so in getting a real appreciation of how realistic is the mineral resource estimate. Critical to the quality of the mineral resource estimate is how realistic is the economic mineral concentration component. In many cases, this parameter is called grade. The industry experiences increased difficulty in achieving realistic grade estimates as the sample grade variability increases. The level of transparency in a mineral resource estimate is very much a function of the competence of the author. An objective presentation of the critical data, such as grade sampling variability can assist a reader in determining if the geology of the mineral concentration is adequately understood and how realistic is mineral resource grade estimate. This paper has considered 75 NI 43-101 style reports released in the past 2 years. The review demonstrates features that were helpful in determining how realistic the mineral resource grade estimate is. If there is insufficient transparency in a report, there is a high probability that the mineral resource grade estimate will not be realistic.

Apr 1, 2005

By Anil K. Beersing

Effective drainage systems are required for reclamation of mine-disturbed areas to control surface water runoff and avoid excessive erosion. For the conventional structural design approach, armouring material necessary to satisfy the design criteria should not move during the design flood event since displacement would uncover the erodible underlying materials. This paper discusses an alternative geomorphic approach for designing drainage channels and watershed landscape. The approach is based on quantitative studies of geomorphic processes operating in a watershed. A design based on the geomorphic approach replicates the configuration, channel regime, sediment volume and hydrology of natural and mature drainage systems. Movement of some armouring material is acceptable in such an approach because the channels are allowed to mature by natural degradation and aggradation, with erosion rates comparable to the natural environment. The key advantages of a geomorphic approach over a purely structural approach include reduced sizes of armouring material, geomorphologically sustainable landscapes, ?walk-away? or maintenance-free design and reduced liability in the future. The geomorphic approach is illustrated using the example of a coal mining operation in northwest U.S.A. The paper discusses field data collection, design criteria, typical design details, and construction methods.

Apr 1, 2005

By Joseph Sawicz

By now, the concept of remotely controlling heavy equipment in underground mines has become commonplace. Personnel safety is the biggest justifier for remote control, followed by an inherent cost saving (in certain cases) when wireless video is added to the mix. There are a handful of vendors targeting this need, and for years the mines have remained loyal to their brand. But as the number of remote-control related accidents and maintenance costs increase it forces our industry to take another look at this commonplace concept. And as the blinders are taken off, the mines are getting the revelation that not all remote control systems were created equally. This paper highlights the differences between various remote control systems, and then moves into an in-depth look at HARD-LINE?s package which drastically cuts maintenance costs, and also provides a solid investment toward full Tele-operation.

Apr 1, 2005

By Warwick Bullen

A hypothetical economic model has been developed for diamond projects in the Canadian Arctic using data from recent exploration and mining projects. The model reflects economic conditions as it applies to the diamond mining industry in the Canadian Arctic at the present time. The economic model captures pre-production expenditures, production data, and post-production costs. Before- and after-tax cash flows are derived from the data along with the relevant economic criteria. From the corporate perspective, the model provides guidance as to the minimum size and/or in-situ value per tonne requirements of targets being sought in order to ensure economic success and probable exploration and development expenditures. From the government perspective, the model provides an indication of income and mining tax revenues that can be expected from a particular diamond project. The model shows, on average, diamond projects in the Canadian Arctic are expensive to explore for and develop, but are economically robust. They generate great economic return for mining companies and significant amounts of tax revenue for governments. The fact that diamonds can be transported directly from the mine site by air makes them particularly attractive targets for mining companies that operate in the Canadian Arctic.

Apr 1, 2005

By Brian K. Ayres

Inco Limited, Ontario Division is currently in the process of decommissioning the Whistle Mine site located near Sudbury, Ontario, Canada. The most significant component of site decommissioning involved relocating approximately 6.4 million tonnes of acid-generating waste rock to the open pit from two adjacent stockpiles. An engineered cover system was designed for the backfilled pit to reduce the long-term production of acid rock drainage. Geochemical modelling was conducted to assess the effectiveness of various cover options on the longterm water quality of the backfilled pit. Results obtained from performance monitoring of cover system field trials at the site and estimated full-scale construction costs were used to select an appropriate material for the cover system barrier layer. The two-dimensional soil-atmosphere model VADOSE/W was used to develop a calibrated model of covered waste rock based on field data obtained from the cover trials, which was subsequently used to predict net percolation and oxygen ingress through various cover system alternatives for site-specific climate conditions. Erosion and landform evolution numerical modelling was completed to assist in designing the runoff management system and final landform for the pit cover system. The potential impact of various physical, chemical and biological processes on the sustainable performance of the pit cover system was also considered in the design process. This paper provides an overview of the design and construction of the backfilled pit cover system.

Apr 1, 2005

By Matthew R. Ward

This paper aims to describe the reasons and methods to extend enterprise networks into underground mines. Currently mines use a number of communication networks for telephones, PLCs, two-way VHF radio and computer networking. Each system can have different wiring, protocols, converters and interfaces all which require expansion and maintenance. The convergence of voice, video and data using Ethernet and TCP/IP has the very real benefit of one ?wire? for underground networks. Now that the majority of underground equipment can communicate using TCP/IP, network convergence can offer reduced network expansion and maintenance costs. Cost savings are good, but the truly exciting aspect of network convergence using Ethernet is the low-cost, high speed wireless networking now available . These wireless networks offer an opportunity to facilitate mining automation even on a small budget. How would mine operators change they way they operate if they could gather vehicle location and data in real time? What about controlling equipment remotely? The list of applications is long and includes traffic control, dispatching, real-time ore blending, tele-operation, automated production reporting, vehicle health monitoring, elimination of paper forms and immediate network access for surveyors and geologists. An ideal converged network for underground mining would be robust, inexpensive, easy to expand, enable fast and secure connections while keeping voice communication performance equivalent or better than what is now provided by VHF radio

Apr 1, 2005

By C. Guo

The Mildred Lake Settling Basin (MLSB) is the largest disposal site for mature fine tailings (MFT) at the Syncrude Canada Ltd oil sands plant. Over the past years (since 1997), there has been a marked change in the consolidation behaviour of MFT in the MLSB, which is attributed to microbial activity. Methane-producing microorganisms, known as methanogens, have become very active, and large amounts of biogas (mainly methane) have been produced. In certain regions within the MLSB, gas bubbles are released to the water surface of the tailings pond. Continued field monitoring of the MLSB has provided convincing evidence of the rapid densification process (rapid water drainage from the tailings). This phenomenon contradicts the consolidation models for MFT developed over the past 20 years. The above phenomenon has also been reported at the oil sands tailings ponds operated by Suncor Energy Ltd. in Fort McMurray. This rapid densification has caused pumping challenges in the transfer of fine tailings from the Mildred Lake Settling Basin for the creation of composite tailings. The rapid densification of the MFT may also have potential positive effects in accelerating the reclamation of the oil sands fine tailings. A field and laboratory research program is underway to study the mechanism leading to the rapid densification phenomenon. Systematic field investigations were performed to determine the distribution and characteristics of the rapidly densified MFT. Gas bubble distribution on the water surface was mapped to determine the zones of different biological activities in the pond. These field investigations provided solid ground for further experimental and theoretical research. A number of small-scale column tests were carried out to observe the gas evolution and to measure the changes of some geotechnical parameters under different microbial activity. Also, a series of gassy MFT densification tests are being conducted to study the mechanism of the rapid densification of the MFT under microbiological activity. A review and discussion of the research program is given and some preliminary research results are presented in the paper.

Apr 1, 2005

By Fidelis T. Suorineni

Rapid drifting enables quicker access to orebodies, higher productivity rates and a resultant reduction in activity costs. Increased advance rates, by examination of the key components (face preparation and drilling, hole loading and blasting, scaling, mucking and support installation) in the development cycle, and optimizing these processes is a high priority for research in the Canadian mining industry. Support installation time alone is typically 36 to 46% of the total development cycle time. A reduction in support installation time or techniques and alternative scaling strategies could result in significant gains in drift development advance rates. Support Staging and hydroscaling within the drift cycle could offer alternative drift development sequences that could reduce the overall cycle time. MIRARCO?s research into the support and hydroscaling processes for rapid drift development also suggests that there are many other factors (e.g. mine ventilation services) that have a significant impact on the rate of advance. These factors should be considered to promote and manage safe and rapid drift development. Constraints to the rapid drift development processes can only be overcome by sound construction management practices. In other words, the goals of rapid drifting can be achieved by the implementation of contractor-type construction management. This paper examines various constraints and processes affecting rapid drift development and draws attention to other factors affecting safe rapid drift development.

Apr 1, 2005

By Ken Witherly

Modern airborne EM surveys typically acquire more data than is processed or analyzed at the time of acquisition Suitable additional processing can provide more diagnostic information, thereby allowing for more effective ranking and hopefully, follow-up of outcomes

Apr 1, 2005

Stope performance and geotechnical information at Xstrata Zinc George Fisher Lead-Zinc-Silver mining operations have been analysed in detail since the beginning in October 2003. This work has been included in a joint dilution study between Xstrata Zinc and the University of Saskatchewan. This paper presents an analysis of site geotechnical data and stope reconciliation that led to major changes in stope design, a reduction in dilution, and a significant increase in mining efficiencies. Detailed geotechnical data collection for a mine site or particular stoping area represents a large amount of information which is time consuming to review. However, it is this data that can make a significant difference in rock mass behaviour understanding. Simplification and averaging of conditions into zones of similarity, called structural domains, are common approaches for managing large amounts of data. There is a tendency to average rock mass properties to obtain inputs for numerical modelling and empirical design tools. This approach may be misleading if the inhomogeneity of the rock mass is contributing to the failure mode. This paper summarizes a novel approach for rock mass characterisation and stope design in a bedded sedimentary rock mass.

Apr 1, 2005

By Paul T. Fitzgerald

Risk financing solutions are emerging to fully address environmental liabilities for mining operations. Supported by specialized insurance and alternative risk transfer (ART) products, mine owners can fund, cap and guarantee the environmental liabilities and closure obligations of a mine within a financial structure that will be acceptable to regulators. An environmental risk financing program will permit an owner to transfer the liabilities and indeed the ownership of a site to a third party that has the ability and resources to responsibly execute the closure plan. A properly structured program will be financially viable for the owner and will also respond to community and environmental opposition concerns about sustainable development and the environmental legacies associated with mining activities.

Apr 1, 2005

By Sibabrata Patnayak

A major problem during shovel excavation in oil sand mining is the variability of material diggability resulting in varying mechanical energy input, cycle time, energy consumption, wear, and stress loading of shovel dipper-andtooth assembly. This variability greatly influences the mining equipment performance. Different approaches such as empirical ground classification systems, analytical methods, and performance monitoring that are used to determine diggability of groundmass are reviewed. It is concluded that the existing empirical diggability classification systems are site specific and mostly based on rock and therefore, cannot be used for shovel excavation in oil sands. The O&K wedge test is a simple and useful index test for establishing correlations between cutting resistance and geotechnical properties of coal and other soft rock overburden material. But this test, when performed on small size unconfined oil sand samples, may not give reliable indication of diggability because of the boundary conditions on the specimens. Digging predictions made using analytical and laboratory digging models need to be verified with performance monitoring data to better understand the digging effort in oil sands.

Apr 1, 2005

By R. Kwiatkowski

Agenda ? Health Canada Protocol _ Screening Level Risk Assessments (SLRAs) Contaminants Foods Exposure Pathways COPCs _ Site Specific Risk Assessments (SSRAs) In-depth, quantitative Monitoring Exposure estimates Food Issues in Environmental Impact Assessments ?Country Foods? ? Foods gathered from the project area and consumed by local residents.

Apr 1, 2005

By Glenn Ferguson

BACKGROUND Metals Risk Assessment at Contaminated Sites ? The field of metals risk assessment has advanced rapidly over the last five years ? Significant uncertainties and data gaps remain that require additional research if accurate assessments are to be conducted ? Research is being conducted by regulators, external institutions and academia ? Risk assessment practitioners are in need of answers or solutions TODAY

Apr 1, 2005

By Matthew D. Meyer

SMART, an association of surface mining companies formed in 1995 to develop a coordinated approach to technology development for the mining industry, has recognized the need for the establishment of a worldwide database that continuously collects mining equipment data and provides metrics related to productivity and cost. Under the auspices of SMART, Syncrude Canada, Suncor Energy and Albian Sands Energy (three oil sands mining operations located in northern Alberta) have established a pilot project for mine benchmarking. This presentation will include a review of the pilot progress including: ???Data gathering techniques: means of collection and storage, proposed practice for data control and normalization, access to data/reports and format for data. ???Reports/analyses for individuals, across groups, within the total industry pool and publicly. ???Security and confidentiality of information belonging to identified parties. ???Sharing of best practices among members. SMART has identified two key deliverables to ensure success of the project. First, data supplied from surface mines must be validated and normalized to common definitions and then analyzed to provide participating companies with regular reports that allow them to understand their position and resultant opportunities to achieve world-class performance. This model maintains granularity of the data for each operation that can then be recombined into standard comparisons or specific indices as required. The general categories of: operating delays, maintenance downtime, standby, and scheduled downtime, have been used to frame comparisons. Second, participating companies are looking to go behind the indices to identify and share best practices that distinguish particular operations. The spirit of cooperation between the companies involved in the pilot project is meant to be a model for future expansion of the benchmarking project.

Apr 1, 2005

By P. K. Kaiser

3-D virtual reality (VR) visualization has opened new opportunities for complex 3D (x, y, z), 4D (x, y, z, t) or even nD data interpretation. The integration of common earth models (3D geologic data), mine models (3D excavations and stress), extraction models (1D time sequencing or mine sequencing) and nD monitoring data (e.g., seismic event parameters) into a common mining process model provides a platform for experts in various fields to better design, evaluate, monitor and modify mine plans throughout a mine?s life; from feasibility, through operation, to closure. Viewing seismic data in a stereoscopic VR environment within a mining process model offers data interpretation processes previously unavailable at lower dimensionality. MIRARCO has developed data analysis and viewing processes specifically designed to enhance microseismic and seismic data interpretation in a collaborative, immersive VR environment; bringing mine personnel and expert consultants together to evaluate data and make strategic decisions for cost effective and safe mining. Seismic events cause immediate hazards (rockbursts) and microseismicity causes gradual hazards through its cumulative effect in rockmass degradation. The focus of this paper is on understanding seismicity from a mine safety and mine planning perspective; in particular, how seismic migration patterns relate to the rockmass response to mining. The benefits of innovation in seismic data interpretation are significant, e.g., for hazardous work area identification, allowing better formulation of re-entry policies and workforce allocation planning, as well as allocation of effective support systems to strategic areas of elevated risk. Better understanding of the overall response of a mine to extraction also facilitates mine planning and design, assisting in reducing production costs and thus in enhancing profitability.

Apr 1, 2005

In the past decade, the increased engagement of business in debates around sustainable development has prompted recognition of the importance of biological diversity at the local, national and global scales. Driven by increasing populations that demand rising real incomes, a range of human induced pressures are modifying natural habitats and diminishing their ability to support life. Public policy changes have struggled to arrest the loss of habitats such as wetlands or tropical forests, and the related extinction of plant and animal species. Although conservation legislation and regulation were once the exclusive responsibility of government, new partnerships are now being forged that increase the role of the private sector and non-government organisations (NGOs) in developing and delivering conservation initiatives. Since the mid 1990s Rio Tinto has had to adapt to meet the demands of a rapidly changing conservation landscape. When Rio Tinto adopted its statement of business practice in 1998 The way we work, it explicitly recognised the need to take account of relevant environmental factors in obtaining access to lands, particularly in designated areas of high conservation value. With the revision of The way we work in April 2003, the policy on land access was strengthened through removal of the word ?designated?, thereby signalling recognition of the importance of biodiversity outside of protected areas. In addition, Rio Tinto?s revised land access policy explicitly refers to the use of land that is surplus to operational requirements for habitat protection and biodiversity conservation, subject to social considerations. In late 2003 Rio Tinto further strengthened its commitment to biodiversity with the promulgation of its biodiversity strategy and related position statement, biodiversity principles? (See Appendix 1.1) and technical guidance documents. This commitment is also embodied in a variety of initiatives at the corporate and operational levels, which are reported on annually in Rio Tinto?s Social and environment review. This guide has been prepared to support the practical implementation of Rio Tinto?s biodiversity strategy. The purpose is to provide guidance on how to effectively integrate biodiversity into Rio Tinto?s operations. It is applicable to all Rio Tinto exploration, new development projects and operations, irrespective of whether they have been operational for some years or are at the beginning or end of their operational life cycles. This guidance has been developed to support the Rio Tinto Environment Standards and the Rio Tinto Community Standard and any additional supporting documents as they are developed.

Apr 1, 2005