Technology and Innovation
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The use of cemented paste backfill (CPB) is becoming increasingly more common at underground mines worldwide. Part of any CPB design includes the specification of the (typically) shotcrete barricades that retain the CPB within the stope during filling. Newmonts Tanami Operations (NTO) has started an in situ barricade stress monitoring program. The data from this program will provide a basis for comparison of several models that can be used to model the capacity of these barricades. These models vary in complexity from analytical solutions to 3D numerical models. Part of the comparison will include a discussion detailing the required material inputs and how these inputs were obtained. Analysis of this comparison will provide additional understanding on what parameters affect the ultimate capacity of a shotcrete barricade.
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Tailings are the materials left over after the process of separating the valuable fraction of ore from the gangue. Tailings ponds are engineered structures created using dams, berms and natural features such as valleys, hillsides or depressions. The pumping of tailings slurry into a pond allows the sedimentation of solids from the water. Tailings ponds can be highly toxic because they are used to store harmful waste made from separating minerals from rocks or the slurry produced from tar sands mining. To minimise contamination of underlying groundwater, high-density polyethylene (HDPE) liners are used. These liners are prefabricated sheets that are welded onsite to form a continuous waterproofing membrane that prevents the migration of contaminated water into the environment. Despite their widespread application, HDPE liners have inherent performance limitations, such as leakages at the location of welds, UV resistance, maintenance and repair. This paper considers a new type of sprayable reactive membrane as a waterproofing structure. Permeability tests with the Rowe cell, chemical and durability tests (interaction with water and leachates at different temperatures, oxidation and UV resistance tests) and mechanical tests (tensile strength tests, elongation tests, puncture tests) were performed and compared with conventional HDPE membranes for tailing ponds. Results showed that the new sprayable membrane has good performance comparable with the conventional HDPE membrane and it can be a very attractive solution for tailings ponds liners
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Tailings dam failures have and continue to cause large-scale devastation and environmental impacts. Historically these impacts have largely been predicted using Newtonian hydrodynamic modelling principles resulting in a general overestimation of potential consequences. However, since about 2014 the collective mining industry began developing complex tools to better predict the likely impacts of these failures. The industry has focused on leveraging the latest in computational flow dynamics modelling software and computational hardware to preform non-Newtonian tailings dam break assessments. However, as our tools become more sophisticated so does the requirement on input data. This paper discusses the past modelling approaches and the development of non-Newtonian tailings dam break models. The sensitivity of the flow behaviour is presented through four case studies, showing how this selection influences the outcomes and how previous approaches assuming Newtonian characteristics may present an overly conservative result. It is noted that additional knowledge and expertise will become available as non-Newtonian tailings dam break studies become the norm. In the interim, the uncertainty of these analysis needs to be analysed.
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There are growing expectations of mining companies to operate in a more sustainable manner, with a strong business case for improving waste management and reducing environmental impacts. As the stewardship of tailings come under increasing scrutiny, decision-makers are urged to adopt a robust approach to the selection of a tailings management strategy that encompasses design for closure, and leading practices to lower the risk of catastrophic dam failures, optimise the use of resources, and mitigate environmental impacts on climate change. An integrated analysis, considering economic, environmental, social, and risk aspects of the operation can therefore provide decision-makers with balanced information to ensure the right projects proceed with an optimal business case so that the most cost-effective solution, that does not externalise costs, can be selected. However, literature review revealed that fundamental shortcomings exist within traditional evaluation approaches used for economic comparisons. This paper reports on life cycle cost analyses conducted for comparing various tailings management options under different scenarios. A conceptual case study for the disposal of gold tailings in Western Australia as a slurry, as thickened, or as filtered tailings, was considered. This was done for examining the extent to which potentially hidden costs impact on the total cost of a project. It is suggested that the proposed approach will lead to selection of a tailings management alternative that ensures sound economic, environmental, and social performance is achieved.
Webinar
Focused on providing an update of the CPT-based SBT classification systems using behavior-based descriptions. The update includes a method to identify the existence of microstructure in soils. Examples are used to illustrate the advantages of such a system.
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Image classification is a process whereby the spectral information of an image, based on its digital numbers, attempts to classify individual pixels to a theme or specific object (e.g. vegetation, water, vehicles, people, etc.). The output is generally an image map or mosaic of pixels, each of which belong to a particular theme or identification to produce an independent overlay of the original image. This overlay can be used to provide a post analysis regarding changes that are occurring in a sequence of images or, for example, identify a potential hazard that can trigger an action for human intervention. The accuracy of image classification is based on having enough information to train a model to identify the theme or object of interest. This paper presents the results of a supervised machine learning technique whereby target objects were identified and models run to train the classification algorithm to identify changes in supernatant pond size, rates of rise, detection of inflows of water to an area and presence of mobile equipment. Training images were acquired from site-based static time-lapse cameras that have been taking images since early 2017 of different areas of a tailings storage facility in the north of Chile.
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Open pit surface mining generates process effluents known as tailings. With the continuous accumulation of material in tailings ponds, and to comply with reclamation and water-use regulations, the industry is constantly seeking new technologies that can accelerate the tailings consolidation and dewatering process. Preliminary tools and techniques to screen potential consolidation technologies are valuable to quickly understand the effectiveness of the technology on the bench-scale before larger-scale testing. At present, settling tests have been the ideal medium for bench-scale study, however, this process can be time-intensive. This study compares a potential tool for short-term testing of consolidation, a benchtop filter press, with a standard settling test. The benchtop filter press is commonly used for the generation of specific resistance to filtration (SRF) data, however, the application for use in understanding consolidation is not. In this study, a benchtop filter press was modified to remove the limitation on the dewatering time due to the filter cake cracking, thus allowing dewatering past the liquid limit of the material. Two types of synthetic tailings were developed using a kaolinite and bentonite mix in synthetic process water, with varying solids content, methylene blue indices (MBI) and water chemistries, to mimic the conditions in actual mining samples. The study shows that the modified benchtop filter press results produce similar trends to settling tests and perform as expected with and without polymer addition. The modified benchtop filter press provides data in a course of hours to days, as compared to the settling test data that can take weeks to months to generate. Additionally, work conducted with oil sands fluid fine tailings (FFT) after various treatments, demonstrates that SRF curves from actual mining samples show trends in dewatering time consistent with observed field performance.
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This bulletin provides a framework for classifying different types of tailings based on their geotechnical properties and provides typical geotechnical parameters for the different tailings types. It also presents technologies for dewatering tailings from thickening to filtration.
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The equipment selection for a fine coal tailings dewatering application is filled with numerous challenges and complications. There are known technologies operating in the Australian coal industry such as belt press filters and, recently, solid bowl centrifuges. This paper looks at three known technologies, namely belt press filters, plate and frame filters, and solid bowl centrifuges to dewater thickened fine coal tailings. A comparison of recovery, moisture, reagent addition, solids and volumetric throughput is presented. Some pros and cons of each application will also be provided. Specialised technical information on each application including the major factors that have the greatest dewatering impact on the technologies will be highlighted. Information from an installation from South Africa is shared. The paper assists with the selection process and explains important information that must be brought to light when considering a change from wet disposal to dry disposal. Elements of this paper were previously published in Meiring (2021).
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Innovation flourishes at the intersection of great challenges meeting compelling solutions. Canada's Oil Sands Innovation Alliance (COSIA) is an alliance of oil sands producers focused on accelerating the pace of improvement in environmental performance in Canada's oil sands through collaborative action and innovation. COSIA's membership accounts for over 90% of the oil sands product in Canada. Canada's oil sands producers are competitors and rivals; but they are also partners in a made-in-Canada collaboration model that is helping to redefine, globally, how companies can innovate together, and accelerate solution development to address some of the world's biggest challenges. COSIA companies are working aggressively to accelerate the pace of environmental performance improvement in the oil sands. Canada's oil sands industry is committed to reducing all aspects of its environmental footprint, reclaiming all lands affected by operations, and maintaining biodiversity. To create breakthrough science and technologies, COSIA brings together leading thinkers from industry, government, academia and the public. In addition, COSIA members themselves work together, each sharing considerable in-house expertise, innovation and intellectual property within the alliance, and dedicating substantial funds to COSIA's many environmental performance projects. The unique characteristics of oil sands tailings provide member companies with an opportunity to seek out innovative tailings management and technology solutions for responsible and sustainable growth of this key global energy resource. This keynote address will elaborate on each of the Environmental Priority Areas (EPA), with an emphasis on the Tailings EPA. It will provide the audience with a brief history, achievements, current technical challenges, and opportunities for collaboration to close remaining knowledge and technical gaps to accelerate the pace of environmental performance improvement.
