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"Discrete Fracture Network (DFN) modelling has increasingly being used in many geotechnical and mining engineering problems, the authors believe there is an ever greater demand to provide updated guidelines that address the collection of discontinuity data in the specific context of DFN models. In general terms, the generation of a DFN model requires collecting information on i) fracture orientation, ii) fracture intensity, iii) fracture length and iv) fracture terminations. The International Society of Rock Mechanics (ISRM) suggested methods for the quantitative description of discontinuities in rock masses directly include most of these parameters. However, there are important differences engineers should be aware. To what extent discontinuities can be sampled and which limitations are inherently introduced in the analysis by the sampling methods being adopted represent important aspects that should drive the collection of discontinuity data for DFN analysis; this will require the introduction of a more appropriate set of guidelines bridging the gap between the current, very practical, ISRM methods and the data requirements imposed by the use of new DFN technologies.INTRODUCTIONThe last decade has seen a major increase in use of the Discrete Fracture Network (DFN) approach, both as a stand-alone tool or integrated within more complex geomechanical simulations (Rogers et al., 2014 and Elmo et al., 2014). In particular, the DFN approach offers the opportunity to maximise the use of fracture data collected from mapping of rock exposures and to construct synthetic rock mass (SRM) models. However, the potential of DFN based modelling is limited if there is insufficient care in collecting the necessary structural data at the required engineering scale. DFN models are also subject to the process of data calibration and validation (Hadjigeorgiou, 2012). With DFN modelling becoming an almost integral part of many geotechnical and mining engineering problems, the authors believe there is an ever greater demand to review the process of collecting fracture data in the specific context of DFN modelling.The value of the DFN model depends directly on the quality and quantity of available field data. For example, fracture length (persistence) is an important parameter in DFN modelling; however, this parameter is either seldom available at the pre-feasibility stage due to a lack of exposures (man-made or natural), or engineers have access to limited length data collected along exploratory drifts. Characterisation of rock exposures should also take into account limits of window/scanline mapping techniques with respect to both trace length bias and the effect of cut-off assumptions inherent in the mapping methodology."

Jan 1, 2015

By Joel Werner

Weak metal prices, declining head grade, and increased operational costs are forcing many open pit mining companies to look to their balance sheets for significant cost reductions in order to remain competitive. Maintenance continues to represent a significant proportion of the total operating costs in the mining industry. Compared with the other major cost components of the mining process very little effort has gone into maintenance optimization. The potential payoff from maintenance optimization on the cash cost of the commodity is enormous. A large percentage of these costs are incurred in unscheduled maintenance events, which typically cause serious disruptions to the production process. These maintenance induced production losses can be a significant contributor to the overall operating costs. A structured proactive maintenance approach using the latest advances in technology can achieve dramatic cost reductions and productivity improvements. Remote condition monitoring systems are becoming increasingly commonplace and have the potential to identify problems prior to failure. Detection of equipment degradation prior to failure will enable repairs to be scheduled thereby reducing costs and interruptions to production. Remote condition monitoring technology has evolved rapidly in recent years, with a host of new tools becoming available to assist mine operators in improving their maintenance operations. These tools have capabilities such as: remote real-time vital signs and performance monitoring, alarm/event handling, trend analysis, and maintenance workflow management. When these monitoring tools are used in conjunction with a mine management system the vital signs data can be integrated and associated with maintenance history, predictive maintenance data, operational information, and geographical information. This integrated approach to the management of vital maintenance data will help shift the mobile equipment maintenance paradigm from reactive to proactive. This paper will introduce a proactive approach to the management of the maintenance process and the tools required to facilitate this process.

May 1, 2003

By Eldridge Haynes

IF you ask the average American to define 'total war' he is apt to fumble for an answer. But in Britain everyone knows the answer, because Britain has mobilized its total labour force, including women. If we were to match, proportionately to our population, Britain's mobilization of labour, we should have 60,000,000 people working full time in the armed services, civilian defence, and war industries. Actually we have fewer than 35,000,000 so employed. In Britain two out of every three persons between the ages of fourteen and sixty-five are so engaged. For the first time in the history of any democracy Britain conscripts women for service in the army, navy, and air force. Two hundred thousand British women have been conscripted for the army, known as ATS, meaning Auxiliary Territorial Service. There are more women in the air force than the total personnel of the RAF at the outbreak of the war and almost all of the land base jobs of the British navy are now handled by women. In addition to cooking and office work, Britain's women soldiers and sailors are driving trucks and motorcycles, repairing motor vehicles, packing and repacking parachutes, installing, inspecting, and maintaining gun equipment and ammunition of combat planes after each raid, raising and lowering barrage balloons, forecasting weather, manning harbour craft, sending and receiving radio messages. A normal ack-ack unit is composed of 229 women and 189 men. The women man the gun height finders and predictors, give bearings, and signal to fire.

Jan 1, 1942

By Martin G. Wafforn, George J. Greer

"In early 2014, Pan American Silver Corp. commenced a project to construct a second shaft at its La Colorada underground mine located in Zacatecas State in Mexico. This was the first new shaft development project undertaken by Pan American Silver in the history of the company. The existing mine workings permitted the use of a raise bore for the excavation of the shaft opening, utilizing directional drilling in poor ground conditions to advance the pilot hole. This was an interesting project with many challenges and successes, and numerous lessons learned. The project was successfully completed in 2016, with the shaft operating at full mine production capacity within weeks. INTRODUCTION The La Colorada Mine has a long history dating from at least the 1920’s. The mine is located in the northern portion of Zacatecas State in Mexico in the Chalchihuites area, an approximate two hour drive south from the city of Durango. Pan American Silver acquired the La Colorada mining concessions in 1998, with mine production at that time consisting of only a few hundred tonnes per day. Over the course of the following 15 years, with the addition of an oxide processing plant and some expansions to the sulphide processing plant and site infrastructure, production was eventually increased to a maximum of 1,250 tonnes per day, all of it generated from conventional cut-and-fill stopes in the underground mine. An existing shaft was used to hoist the ore to surface, and over the years Pan American Silver had deepened the shaft and had changed out some of the hoisting plant. However, there were historic workings in close proximity to the shaft that made it unsuitable for personnel transport, and shaft maintenance was becoming difficult. The shaft was increasingly considered as a risk to the long term production continuity, and also to further deepening of the mine. In addition, expanding the capacity of this old shaft was not possible. Drilling of the La Colorada mineralization at depth commenced in 2010, with very good exploration success. As a result, by the end of 2013, the mine reserves had grown to a total of 6.5 million tonnes of high grade ore (388 g/t Ag, 0.36 g/t Au, 2.4 % Zn, and 1.3% Pb). Furthermore there were more (and higher grade) sulphide reserves than oxide reserves at depth. Following the completion of an internal study in 2013 with assistance from one of the international shaft contractors, a decision was made to increase the production from the mine with the construction of a new shaft and a new sulphide processing plant, a project with a calculated payback of 2.2 years."

Jan 1, 2019

By Allan R. Punkkinen

Safe extraction of the valued ore resource in the deep levels of VALE Creighton Mine has progressed in a pillar-less fashion using vertical retreat, slot-slash and uppers retreat methods since the cessation of ?cut and fill? mining in the late 1980?s. Sequencing of the panel extraction and filling has been the key to successful exploitation of high stress orebodies at depth. In late 2010, discussions between the Operating Department and Creighton Ground Control revealed an opportunity to evaluate a trial primarysecondary sequence in the west end of the 400 Orebody at the 2340m horizon. To manage the trial primarysecondary project, a high level risk analysis and management of change was carried out to mitigate potential danger. As part of the requirements, an instrumentation project was conducted in the hanging wall and footwall bottomsills of the secondary panel and within the secondary panel itself. The extraction sequence was modeled with Map3D® software, confirming high stress levels with the advance of the primary panel. Enhanced ground support was installed based on modelling results. A key objective of the instrumentation project was to verify support system response to mining and to obtain knowledge in regards to the behavior of the stope. This paper describes the first time that this type of new innovative instrumented rockbolt technology had been used in a hard rock mining environment. Understanding of the physical deformation mechanisms of ground support in response to high stress conditions is the basis for an effective ground control strategy. The data played an important role in subsequent enhanced ground support system design at the mine and importantly, established the fact that the secondary pillar had not totally failed. Subsequent cavity monitor results helped establish that fact.

Jun 1, 2012

By M. Y. Levesque

The Australian Government?s Energy Efficiency Opportunities (EEO) program launched in 2006 obliges companies that use more than 0.5 PJ (petajoule) or roughly 139 GWh (gigawatt hour) per year to conduct an energy assessment in order to identify measures to improve energy efficiency. The opportunities identified by the mining sector were assembled in the Mining Significant Opportunities Register that permitted companies not yet embracing and adopting an energy management program to see what those who are, were doing and how much energy was saved, and helps disseminate best practice. The measures can be filtered by company, year, category or equipment type. The creation of a central repository of energy efficiency initiatives is valuable but this existing database could be improved; fields identifying the energy and carbon emission savings associated with a given initiative are a surprising omission. Consequently it does not permit the relative effectiveness of different measures for energy and carbon reductions to be readily assessed. A review of energy management efforts implemented in the mining industry, published in peer reviewed journals, corporate sustainability reports or industry publications during the last 40 years has revealed many examples of best practice. However, the lack of a standardized reporting framework in any of these sources has made it difficult to assess the effectiveness and compare the adopted energy management measures ? just as is the case with the Australian register. In an attempt to address these issues, an improved database structure has been created for energy management measures from the mining industry which identifies energy and financial savings arising from energy management initiatives, classifies applications to specific processes or equipment, and recognizes leaders in the mining industry with respect to energy management. The structure of the register includes the key data relevant to energy management in mining that is absent in the Australian version. The mining industry energy management database has been made available in the public domain where stakeholders can examine the best practice examples. Mining energy champions may also contribute to the register by providing case studies; a standardized entry template affords a quality assurance dimension that is absent in other reporting initiatives. Adoption of this database with its standardized reporting mechanism will enhance transparency of the mining industry in energy matters and help it maintain its social license to operate.

Aug 1, 2013