Search Documents

By Karsten Zimmermann

The paper presents a study on the influence of face retreat rate in longwall coal mining on surface subsidence. It shows possibilities to influence dynamic ground movement by using a specific and controlled winning regime. For this, a dynamic stochastic prediction model used by DMT in Germany will be proved and adjusted on the specific character of geology in the Northern Appalachian coal field. Occurring ground movements such as inclination, curvature and deformation can be analyzed under static and dynamic points of view. It is theoretically shown that the face retreat rate has only a small influence on the static deformation values, but directly affects rate and acceleration of subsidence and deformation processes. The study shows that because of low mining depth and high mined thickness, static deformation values have the largest impact to surface objects. This implies that high face retreat rates don?t affect the impact on surface objects.

Jan 1, 2007

By Gabriel Esterhuizen

Observations of pillar conditions in limestone mines showed that the presence of weak bands in the limestone can result in pillar damage at stresses that are lower than one would otherwise expect. The objective of this National Institute for Occupational Safety and Health study was to investigate the mechanism of failure caused by the presence of weak bands by using a series of numerical models based on realistic physical properties. The effect of the weak bands on pillar strength was also investigated by developing a series of pillar models with different width-to-height ratios and determining their strength by simulating a servo-controlled loading condition. The material properties of the bands and the limestone were varied and their effects on pillar strength were determined. Model results demonstrated failure development similar to the pillars observed in the field. The weak bands were seen to develop tensile stresses in the limestone as they extrude under increasing stress. The limestone fails in tension at a much lower stress than its expected uniaxial compressive strength. The results showed the load bearing capacity of the pillars can be reduced significantly by the presence of multiple thin weak bands. The degree of strength reduction is largely dependent on the compressive strength, the frictional resistance and the thickness of the weak bands. Single weak bands do not affect pillars as severely as multiple bands. However, the model results show that a single thick weak band, which comprises more than about 2 percent of the pillar height, can cause a significant reduction in pillar strength. The weakening effect of the bands become less severe as the pillar width-to-height ratio is increased. Field observation of spalling and failure associated with weak bands in limestone pillars show that the failure mechanism in the models resembles the observed failure. The model results provide insight into the important factors affecting pillar strength in the presence of weak banded materials.

Jan 1, 2007

By Leslie F. Sawatsky

Failure of drainage works is one of the principal threats to the sustainability of mine closure facilities but the risk can largely be remedied by appropriate design of mine closure drainage facilities. The feasibility of sustainable mine closure facilities that avoid failure of drainage systems needs to be established during the early stages of mine planning, before mine disturbances make sustainable closure uneconomical. Experience in mine development shows there is often enough latitude in mine plan development to incorporate measures with neutral economic consequence and positive environmental benefit. Project managers need to resist the temptation to develop mine plans and closure drainage plans independently. Integrated mine planning with effective inputs by environmental specialists and drainage designers may affect the overall mine configuration, footprint and schedule. Key issues pertain to the end pit location, waste dump configurations, pit infill elevations, fluid impoundments, diversion channel routing and preservation of flows to receiving waters. Guidelines with illustrations of suitable practices are presented to assist mine planners.

May 1, 2004

By G J. Massoth, K Faure, A G, R G. Ditchburn, I J. Graham

From modest beginnings in 1996, research into the mineral potential of New ZealandÆs Exclusive Economic Zone has progressed into a major multidisciplinary component of GNSÆs recently funded 6-year æMineral Wealth of NZ and its EEZÆ Programme. In excess of $7.5 M of research funding has been expended, plus $10 M leveraged via collaborations with NIWA (NZ), NOAA (USA), JAMSTEC (Japan), U. Kiel (Germany) and ANU (Australia), whose scientists have contributed hugely to research cruises, as well as subsequent analysis and publication. The 1999 NZAPLUME I cruise was the first research expedition to systematically locate, and chemically characterise, submarine hydrothermal venting associated with arc volcanoes of the southern part the Kermadec intra oceanic arc system. This was followed by the 2002 NZAPLUME II and 2004 NZAPLUME III cruises to the mid- and northern-sections of the Kermadec arc, respectively. Combined, these cruises have surveyed 1300 km of the volcanic chain (from Whakatane to Monowai), including 34 major volcanic centres. Together with concurrent surveys in the Tonga arc, this is now the longest continuous stretch of intra oceanic arc to be surveyed for hydrothermal emissions. Most of the volcanic centres are characterised by simple cones although 30 per cent contain caldera complexes, and compositions range from basalt through to rhyolite. Massive sulphide mineralisation has been recovered from several volcanic centres in the southern Kermadecs (Clark, Rumble II West and Brothers), suggesting the existence of significant Au and base metal bearing deposits along the arc front.

Jan 1, 2005

By G. Winkel

Safety conditions in industry have greatly improved over time. However, around the world, in Canada, and in each province or territory, people are still the victims of serious industrial accidents. The increasing safety of people at work then continues to be an imperative in industry today.<p> So how do we achieve a workplace where no one gets hurt? Well, in simple terms, folks need to be protected from unplanned exposures to equipment or energy sources that can do harm. If you think about it, all of our efforts in loss management and safety should then be directed toward avoiding these uncontrolled events. And it works! Our safety performance over the years has enjoyed tremendous improvement due to this support for loss management and safety. We now explore best practices toward achieving that next step in safety improvement.<p> As shown following, a large combination of loss management activities act together to support safety performance. Many of these activities are interrelated and some people have described them as the ?inputs? into an approach or program for achieving safety. Using this description, it follows that the ?outputs? of the program are some of the advertised measures of safety we see around us today, such as injury frequency rates. <p> It is asserted that a leadership focus to regularly measure safety and loss management activites (so-called ?inputs?), as a basis for taking supportive actions to ensure their effectiveness, is the basis for safety results (so-called ?outputs?) that consistently achieve high standards of excellence.<p> The concept of managing input activities, as enabled by effective measurements, can significantly act to transform our focus and priorities in the workplace. Supporting input activities like strategies, plans, or procedures with our best efforts will get us to our intended goals. Tracking outputs alone will not.<p> Safety and production have traditionally been cast as competing objectives. When both objectives are mutually supported and considered, however, people will invent ways of doing work that support both safety and production, and any other business parameter. When done right, innovation through meaningful involvement of affected people in the workplace will support safety excellence in a manner that in turn improves business efficiency overall.<p> For a workplace to be safe, it then requires everyone?s help and participation to make it happen, a collaborative effort by management, leaders, and frontline folks with the power and responsibility to take appropriate action at every level in the organization. In this way, everyone becomes a leader in safety.<p> The achievement of commitment to loss management input activities by folks in the workplace is the basis for attaining safety excellence. A workplace founded on commitment supports a safety culture with a vision for safe work performance at outstanding or world-class levels of achievement.<p> One may ask if injury incidents will be eliminated with this commitment and focus on workplace safety? Well, despite our best efforts in this area, there is never a guarantee that things can?t go wrong. We are simply not perfect. There remains in our workplace complexities and unanticipated risks that can have disastrous consequences if not managed at every moment. And when it goes wrong, we need to know we?ve truly tried our best, and now we have more to learn so we can get even better. <p> That?s the challenge represented by the safety imperative, a challenge to take safety performance that next step, a fulfillment of our commitment to the moral obligation we have to each other?s safety. It?s an effort that will continually raise the bar of world-class safety performance achievement for future generations. It?s a legacy we can be proud to be part of.

Sep 1, 2004

By G. Winkel

"Safety conditions in industry have greatly improved over time. However, around the world, in Canada, and in each province or territory, people are still the victims of serious industrial accidents. The increasing safety of people at work then continues to be an imperative in industry today. In addition to protecting people, safety has been shown to make good business sense in any industry.The road to safety improvement is built on establishing a culture of safety that forms the basis for how work gets done in a company. Most importantly, an effective safety culture is built on the full engagement and participation of workers and leaders alike, who share in a vision for safe work performance where “no one gets hurt” and “everyone is a leader in safety.”Let’s learn together on how we can make a safety culture happen. The resulting bias for safety will ultimately save lives, and fulfills our moral objective to strive for safety excellence. IntroductionWe have the good fortune of living in democratic countries where freedom and the value of human life are key beliefs. These beliefs translate into the moral obligations and laws that we value and uphold in our society and life today.A minesite or workplace is simply a necessary part of our society where people earn a living. It is a place where our moral obligations and laws equally apply, a place where human life is of ultimate importance and value. In the early years of industry, this value has not always been evident. Take this description of a tragic accident reported in a coal mine on December 8, 1879:“Oliver Thompson, shaftman, aged 35— While taking wooden partitions out of a ventilation shaft, he fell off the work platform a distance of 100 yards, there did not appear to be anything unusual to account for this accident.”"

Jan 1, 2004

By Y Xie, D Willingham

Predictive maintenance (also known as ‘condition/health monitoring’) refers to the intelligent monitoring of equipment to avoid future failures. In contrast to conventional preventive maintenance, the maintenance schedule is not determined by a prescribed timeline; instead, it is determined by analytic algorithms, such as machine learning, using data collected from equipment sensors and/or via simulation.Predictive maintenance offers the following benefits for operators and equipment manufacturers:- reduces equipment downtime by identifying issues before failure, thereby enabling convenient scheduling of equipment service and extending equipment lifetime- determines the root cause of the failure, enabling appropriate service to be performed without utilising resources to determine a diagnosis- avoids the unnecessary costs of maintenance and unexpected failures- improves safety and product quality.Algorithms and data are critical to predictive maintenance success. Sensor data is first preprocessed using advanced statistical and signal processing techniques; it is then combined with predictive modelling techniques, such as machine learning, to estimate equipment health.Once tested, predictive maintenance algorithms may be used in an operational setting within an IT environment, such as a server or cloud. Alternatively, algorithms may be implemented in an embedded system directly on the equipment, allowing for faster response times and significantly reducing the amount of data sent over the network.CITATION:Willingham, D and Xie, Y, 2017. Predictive maintenance modelling for bearing-based equipment, in Proceedings Iron Ore 2017, pp 627–630 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Andrea M. Ouchi

A major focus of ground control research presently being conducted by the Geomechanics Group in the University of British Columbia Mining Engineering Department is to incorporate weak rock masses (RMR76 less than 50) into existing empirical design relationships. An emphasis is being placed upon the updated span design curve/critical span graph originally developed at UBC. The original database has been augmented by mapping of one mine in Montana and of several mines within the Carlin and Getchell Trends of Nevada. In addition, a neural network analysis has been performed and modifications of the span design curves at the lower RMR76 range have been made. The common factor in all the above mentioned mines is a weak back and/or walls. In most cases, the ore zone is the weakest rock unit and must be dealt with to safely extract the mineral bearing rock. This work attempts to provide rock mechanic tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment.

May 1, 2004

By Gilberto Nunez, Ron Eastman, Hector Parra

The prediction of blasting outputs has proven to be a sound engineering tool to provide a guideline for design improvement. It has also been demonstrated to be extremely useful in critical situations when production can be compromised and there is no chance for error.

Jan 1, 2015

By S F. Simmons

The Ohaaki Rhyolite and the Rautiwiri Breccia are two volcanic units occurring in the shallow and deep parts of the Broadlands-Ohaaki geothermal system. Alteration of these units by chloride waters results in distinct mineral assemblages that also have distinct whole rock compositions. The Ohaaki rhyolite is altered to an assemblage dominated by quartz, adularia, illite and pyrite as a consequence of silica, potassium and sulfur metasomatism. Locally, these rocks contain up to 0.5 ppm Au. The Rautiwiri Breccia by contrast is altered to an assemblage dominated by albite, adularia, quartz, illite, chlorite and pyrite in association with modest sodium metasomatism. Whole rock oxygen isotope compositions of altered rocks range between 3.3 and 7.5 ë, and are generally lower compared to their fresh rock equivalents having values of 9.5 to 10.6 ë; the result is broad pattern of lower values with increasing alteration intensity.

Jan 1, 2002

A model has been developed as part of the AMIRA P420 Gold Processing Technology Project to simulate the recovery of gold by centrifugal gravity devices. The model (which is available online) uses the simulation methodology developed by Laplante et al (1995) to predict gravity recoverable gold (GRG) recovery under varying operating conditions and circuit configurations. In addition to predicting GRG recovery, the model also predicts the GRG content and size distribution of the cyclone overflow and underflow. The predicted overflow GRG content and size distribution can be used as inputs for a leaching model in which size dependent leaching rates are applied for each size class of GRG and non-gravity recoverable gold (non-GRG) in the cyclone overflow, allowing size-by-size leach recoveries to be determined for GRG and non-GRG. The application of the gravity model and leaching model are demonstrated using a case study. The simulated gravity recovery and leaching performance showed excellent agreement with the measured values. The developed models can be used to assess the sensitivity of gravity gold and leach recoveries to varying feed GRG content, GRG size distribution, gravity circuit feed rate, classifier performance and leach residence time. The described methods can be used to optimise new and existing gravity and leaching circuits.

Aug 1, 2010

By Richard Phiri, Mike Milupi, Jackson Kapobe, Anton Lemmer, Charles Mazala

Sustainability of plant operations in a rapidly changing mining environment requires a well-trained workforce to ensure smooth running of operations. To ensure availability of trained labor, Mopani Copper Mines PLC set up a training facility in 2013. The school offers training in Engineering, Mining and Process. The engineering section enrolls grade 12 school leavers for artisan training. Mining section offers comprehensive safety induction program to employees and contractors to meet the Mopani zero tolerance accidents safety policy. The process training section offers advanced training programs for plant operating personnel and university graduates. The program includes needs analysis, theoretical metallurgical modules, practical plant training and e-learning modules. The school also offers assaying and sampling courses. All the above courses are extended to individuals and other mining houses outside Mopani wishing to have their personnel trained. The Mopani sustainable development academy ensures that contractors engaged on the Mopani sites are fully registered, comply with all relevant regulations and have undergone induction program before they can be allowed to work on the mine. INTRODUCTION “Sustainable operation of the mining industry requires a continuous supply of trained human resources” (Kapobe et al., 2018). The publication by the Asian Development Bank (2014) argued that there was a mismatch between the demand for high-level skills and the oversupply of low-level skills. Globally, the mining industry requires continued supply of skilled manpower for its complex operations and long term projects whose sustainability is absolutely necessary. Implementation of newer technologies in plant operations to ensure cost effective and efficient operations requires trained and skilled labor at various levels to handle ever-changing challenges. Dutz (2007:152–156) made three recommendations for Building Worker and Management Skills in India: Strengthen enterprise - based training. The government should help ensure that the benefits of in- service training are widely recognized by enterprises, while simultaneously providing strong financial incentives Improve vocational training - Vocational education and training systems have been unsuccessful in preparing graduates to meet market needs, particularly because of a lack of interaction with industry. Public and private vocational education and training providers should be strengthened to make them more responsive to industry demands. Curricula should be updated to reflect modern technologies. Strengthen business, management education, management of research and commercialization - business and management education should be strengthened through public-private partnerships. Innovative management courses should be introduced. Although these recommendations were made for India, they also apply to Zambia and other low and medium income nations.

Jan 1, 2019

By D Cumming-Potvin, S W. Jacobsz and E Kearsley, J Wesseloo

This paper describes a physical modelling program that recreated block cave propagation in a geotechnical centrifuge. A brief description of the design of the test along with the sample material and monitoring equipment is given. The samples tested showed caving behaviour and fragmentation distributions that one would expect from caving mines, with one cave deviating due to pre-existing major discontinuities in the sample. A series of fractures formed ahead of and parallel to the cave, implying that an extensional failure mechanism may play a larger role in cave development than previously thought. The results of acoustic emission monitoring of the tests show a seismogenic zone advancing ahead of the cave; however, the quantity and quality of the data is too limited to draw any further conclusions.CITATION:Cumming-Potvin, D, Wesseloo, J, Jacobsz, S W and Kearsley, E, 2016. Results from physical models of block caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 329–340 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Michael S. Zhdanov

One of the major problems of mineral exploration is the ability to reliably distinguish between uneconomic mineral deposits and economic mineralization. While the mining industry uses many geophysical methods to locate the mineral deposits, until recently, there was no reliable technology for mineral resources identification and characterization. The main goal of this project is to develop a new geophysical technique for subsurface material characterization, mineral exploration and mineral discrimination, based on electromagnetic methods. The proposed new technique is based on examining the spectral induced polarization effects in electromagnetic data using the modern distributed acquisition systems and advanced methods of 3-D modeling and inversion. The recovered parameters of the relaxation model will be used for the discrimination of different rocks, and in this way will provide an ability to distinguish between uneconomic mineral deposits and zones of economic mineralization using geophysical remote sensing technology (Zonge, 1976). The proposed research and development is undertaken using multi-partner collaboration between the University of Utah, four major mining companies, Kennecott Exploration, BHP Billiton World Exploration Inc., Placer Dome Inc., Phelps Dodge Exploration, and Zonge Engineering Inc., which is equipment manufacturer and service provider to the mining industry. The multi-partner collaboration between the academic institution, the University of Utah, and mining industry helps to identify the appropriate mining target and conduct the field experiment for practical demonstration of the developed new technology, which is an important part of the this project.

Jan 1, 2005

By K. E. Kolm, W. H. Langer

Developing natural aggregate resources (sand, gravel, and stone) creates environmental impacts. A systems analysis method has been designed to characterize the components of the environmental system, identify potential impacts to those systems, and evaluate the extent of those impacts. The step-wise method consists of problem definition, data collection, preliminary conceptualization and characterization, additional data collection, data analysis, and refinement. The method requires analyzes of various systems making up the environment, including land surface, geomorphic, subsurface, and groundwater systems. After system characterization is complete, the method focuses on identifying and evaluating potential environmental impacts to determine acceptable mining strategies.

Jan 1, 2001

By R. Mensah-Biney

The NC State University Minerals Research Laboratory (MRL) and Waste Reduction Partners (WRP) of the Land of Sky Regional Council joined efforts in 2000 to initiate a technically sound and practical program for the management of high-volume coal combustion by-products (CCBs) in North Carolina. The accumulation of CCBs from coal burning boilers throughout the state of North Carolina posed a substantial storage problem, and the area was overripe for an effective management program, which would be environmentally sustainable. In particular, the public utility generators had filled storage ponds on their properties, and the storage overload had grown to critical proportions. Much the same situation existed for paper mill biosolids, which were stored on site in landfill cells along with daily output of CCBs from the mill boilers. A conversion process via the patented pyro-process12 (US Patent No. 5,342,442) to produce synthetic light weight aggregates (LWA) from CCBs and paper mill sludge was conceived to process large quantities of both these waste materials. MRL and WRP initiated and formed a consortium that brought together academia, private industry and state agencies to evaluate the production of LWA by the pyro-process. The industry partners included representatives from the power companies, industrial ash generators, expediters for coal ash products, as well as concrete block manufacturers. It was important to welcome interested parties from not only the western North Carolina area and other parts of the state but also from neighboring states including Tennessee, South Carolina and Georgia. Membership of this consortium evolved during the intervening years to include the following participants and supporters: Progress Energy Carolinas; Duke Energy; Santee Cooper; Full Circle Solutions; Land-of-Sky Regional Council; NC Department of Pollution Prevention and Environmental Assistance; Ecusta Business Development Center; Blue Ridge Paper Products; Jackson Paper and Manufacturing Company; Miller Perlite; Appalachian Products; General Shale Brick; Metromont Materials; Small Business Technology Development Center of the University of North Carolina system and North Carolina State University The initial development program conducted at the Minerals Research Laboratory (MRL) was to formulate an acceptable LWA product, which fulfilled user specifications for light weight concrete block and structural concrete application. Support work and program coordination efforts were furnished by retired technical volunteers in WRP. The work advanced steadily, using proven technologies well established in the mineral industry, to generate a very satisfactory LWA. The consortium then concluded that a more comprehensive CCB conversion program would have more appeal for full scale manufacture and commercialization, if a variety of products from CCB separation were generated. This product assortment would include bottom ash, low carbon fly ash, recovered carbon of high purity, as well as the synthetic LWA. The bottom ash would serve the concrete block market, the fly ash was in demand for ready-mix concrete, and the high carbon product could be pelletized and used as a fuel for reburn or by the steel industry, and the LWA was a sought-after component for light weight concrete applications. After scouting all these potential markets and finding them to be viable, the consortium then inaugurated an integrated pilot plant program for the CCB separation and conversion. The plan was organized in three (3) parts: (1) Phase I ? bench scale evaluation studies (2) Phase II continuous pilot plant evaluation and (3) Phase III ? conceptual commercial plant design including marketing efforts and attraction of business entrepreneurs to build a full scale manufacturing plant. Phase II would serve to validate the process in a continuous mode and produce substantial quantities of products for preliminary marketing efforts and for demonstration-of-use purposes. The consortium agreed to the name, CAROLINA ASH PRODUCTS, (CAP), for the integrated pilot plant program. The products generated might be designated with the CAP label as: bottom ash would be named CAP Granules, low carbon fly ash would become CAP Ash, recovered high carbon product would be CAP Carbon, and LWA would have the name CAP Stone. Phase II of the program processed 20 tons (18 t) of ponded ash from Progress Energy storage at a rate of 600 lb (271 kg) of raw ash per hour with favorable results. PRELIMINARY STUDIES Prior to committing laboratory research and development effort as well as support and coordination activities to this program, it was necessary to determine (1) the level of need for a freshly launched CCB reutilization program in this state and (2) what degree of versatility was necessary for such a process. State agency records and a survey of recent boiler operations indicated that in the state of North Carolina at least 77 facilities manage CCBs from their boiler operations. Despite continuing development efforts in more eastern parts of the state, the use of CCBs for commercial applications has not increased to a level which alleviates the need to store vast quantities in private monofills on the generator?s property. More than 1.25 million tons (1.13 million t) of CCBs are landfilled in NC annually, with 300,000 tons (271,985 t) per year generated in western NC alone. Many different boiler types, which span both very old units and those that are modern and efficient, were to be found. These included stoker-fired units, pulverized coal boilers, slag-tap furnaces, and fluidized bed combustion boilers covering a range of sizes. Any systems designed to separate CCB components from all these sources and convert them to useful secondary products would need broad processing latitude and flexibility. Up to the present there has been a paucity of research done in the western part of the state to find productive alternatives to storage in landfills. With tipping fees in our largest landfill now approaching $40 per ton ($44 per t) and escalating transportation fees (about $200 per truckload up to 40 tons, traveling a distance of 25 miles), the problem has become urgent both economically and ecologically. A well-designed, integrated wet process for CCB separation into value-added products had much potential to be less expensive than landfilling as well as to provide saleable materials with acceptable profit margins. These preliminary investigations also revealed that other major waste streams, in particular paper mill sludge and municipal and animal waste biosolids were important candidates for priority attention. Since these biosolids could furnish the organic component of a synthetic LWA product, they could be consumed as part of the same program. This added interest value to a growing list of partners to support and participate in the program.

Jan 1, 2009

By Chu E. Ho

Jet grout column formation at large depths are prone to several uncertainties, such as inaccuracy in setting out boreholes, drilling deviation, soil variability and reduced jetting energy at the nozzle. This would result in shorter cutting distance of the jet, with potential lack of interlock between grouted columns. A design strategy for mitigating the risk should include a soil investigation program aimed at discovering potential variability in soil conditions at the locations of jetting. Determination of soil strength profiles with depth would be useful for evaluation of jetting parameters and prediction of the achievable cutting distance at any depth. Selection of design column spacing should include allowance for setting out accuracy, verticality of the boreholes and the achievable jet cutting distance. For deep jet grouting operations, it would be necessary to take into account the energy losses at the nozzle inlet; however the increase in the presiding pressure at the nozzle outlet at depth is small relative to the range of jetting pressures commonly employed and would not affect the cutting distance to any significant degree. Design column spacing should not be so close as to cause problems with ?masking? which may lead to localized ungrouted zones of soil. For effective field control, boreholes should be cased up to the top elevation of the grouted zone so that the orientation of the borehole can be measured prior to grout injection. An analytical equation for calculating the cutting distance is proposed for adjusting jetting parameters where necessary to compensate for drilling deviation and changes in soil conditions. It is preferable that jet grouting trials be executed at elevations that correspond to the actual production jet grouting depths for accurate evaluation of jet cutting performance.

Jan 1, 2008

By M. Haase

[ ] How important is a robust communications system for your mine site in order to meet operational and safety requirements? Do you currently have VSAT in place and need a low cost, high quality multi-line VoIP phone system at the site? By adding a single, compact piece of hardware, you can utilize your existing satellite internet connection and have as many as twenty-four separate phones lines from a single unit. The platform is scalable for any size of operation and can be implemented above or below ground.

Jan 1, 2012

By Steve Kral

Conference themes are usually chosen by organizers to reflect the current state of the industry. The Colorado Section MPD came up with what may be the most appropriate theme of a mining conference during the last few years. The local SME MPD section’s theme of its 56th annual conference was “The Wild, Wild World of Mining.” The current boom can be felt in all aspects of the industry, including exploration, mining, processing, sustainability, and economic and political issues. Each of the 25 speakers at the conference, held in Colorado Springs, CO, touched on how the boom has impacted each of those aspects. The meeting attracted about 110 people from around the world.

Jan 1, 2006

By P. Burmeister, R. A. Errath, A. Sapin

Sag Mills are becoming bigger in size almost every year. Concentrator plants are also becoming larger with more SAG and Ball Mills units with Gearless Mill drives installed in one plant. In contradiction to this development, concentrator plants are being built in increasingly remote areas, where the power supply and network conditions are not necessarily covering the needs for the operation of such plants. This paper describes sources of harmonic distortions and possible approaches to solve this problem. It also illustrates the permissible tolerances in terms of commutation of power electronics, based on already realized installations. Furthermore it explains how, and with which measures, harmonic currents created by non-linear loads with SAG and Ball Mill drives can be handled, and how harmonic standards can be fulfilled accordingly. Finally, this paper gives an overview about the technical impact of a strong versus weak network, and the economic relationship between them.

Jan 1, 2001