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By Gilbert Sauriol

The mining complex, which the Mines Gaspé division of Noranda Mines Limited has operated in Murdochville since 1954, includes open pit and underground mines, two mills, one leaching plant and a smelter. The under- ground mining uses predominantly a large scale room and pillar method, rooms 15 m wide, 30 m high and 300 m long being common. Ore production is effected by 4.5 m3 front-end loaders and 32-tonne trucks powered respectively by 225 and 325 kW diesels. Daily dust and gas readings show that air quality can be maintained at an acceptable level with much less ventilation than that normally specified. This paper emphasizes the point that air requirements should be based on Air Quality Standards, thus allowing an operation to benefit from favourable conditions or from improvements such as exhaust treatment, fuel alteration, etc.

Jan 1, 1983

By K. R. Griffin

Atmospheric conditions underground are constantly changing and from a safety perspective, it is critical to identify when conditions are trending abnormally. Atmospheric monitoring in underground coal mines allows mine operators to analyze atmospheric conditions underground in real-time. Real-time monitoring can then be used to identify whether atmospheric conditions underground have become problematic. The implementation of a risk assessment and management process allows operators to then use a risk-informed decision making to identify comprehensive site specific ventilation parameters. Establishing risk-informed ventilation parameters and tracking conditions relative to these parameters, management can modify ventilation plans as mine conditions develop to manage evolving risks. Ventilation risk assessment and management allows developing atmospheric monitoring technologies to be fully utilized in order to increase safety standards in the United States. This paper reviews general risk assessment approaches, state of the art ventilation based risk assessment, and the risk assessment and management application within the United States regulatory framework.

Feb 27, 2013

By Yuusaku Tominaga, Sukumar Bandopadhyay

A power-series trend curve of elapsed time was estimated by using time series data of measured concentrations of carbon monoxide in the Taiheiyo coal mine, Hokkaido, Japan. The difference between the moving average concentration data and the estimated data from the trend curve showed linear correlation when plotted on a normal probability paper and a correlation coefficient value of 0.99. It is concluded that the estimate of carbon monoxide concentration using moving average values of concentrations compares very well with the results obtained from the trend curve within the three-sigma (standard deviation) range of the distribution. Thus, it is believed the results can be used to monitor and detect abnormal ventilation conditions in a ventilation network such as the occurrence of spontaneous combustion at an early stage.

Jan 1, 2002

By G. Righettini, P. Mousset-Jones

Diesel powered vehicles have made underground mines more efficient, but with the advent of DPM regulations, in most cases, extra ventilation and/or engine emissions control technology will be required. Using fuel cell powered vehicles will not need these measures to be taken. Nine US underground mines of varying production rates and mining methods were studied to determine possible ventilation reductions if their diesel fleets were replaced with identical fuel cell powered vehicles. Factors that might limit ventilation reductions, such as heat and the effects on other pollutants were determined for each mine. The ventilation cost savings and other benefits of fuel cell vehicles show that when they become commercially available they have the potential of being viable alternatives to diesel vehicles.

Jan 1, 2004

By J. S. Stachulak

"IntroductionInco Limited operates nine underground mines on the rim of the Sudbury Basin. These operation s are situated near the city of Sudbury, 589 km west of Montreal, and 363 km north of Toronto. The ores are mined primarily for nickel and copper, and the principal minerals are pentlandite, chalcopyrite , and pyrrhotite. Total ore production from underground is in excess of 51 000 tons per day.The total volume of fresh air supplied to the nine mines is six million cu.ft/min. There are 50 main fans in operation at these mines, powered by electric motors totaling 11 200 kW (15 000 hp).The trend in metal mining during recent years towards mechanization and high-tonnage production methods has greatly increased ventilation requirements. The now of air must quickly dilute and carry away diesel exhaust fumes, dust created by mining operations, and the fumes of the explosives used in blasting. Mechanical ventilation is required to obtain the necessary volume and control, as natural ventilation pressures alone are, for the most part, inadequate and unreliable. In the event of a mine fire or other needs, close control of ventilation is essential.There are two unique heating systems presently in operation at Inco: Creighton Natural Heat Exchanger and Stobie Ice Stopes."

Jan 1, 1991

By J. S. Stachulak

Inco Limited operates nine underground mines on the rim of the Sudbury Basin. These operations are situated near the City of Sudbury, 589 km (365 miles) west of Montreal, and 363 km (225 miles) north of Toronto. The ores are mined primarily for nickel and copper, and the principal minerals are pentlandite, chalcopyrite, and pyrrhotite. Total ore production from underground is in excess of 51,000 tons per day. The total volume of fresh air supplied to the nine mines is six million cubic feet per minute. There are 50 main fans in operation at these mines, powered by electric motors totalling 11,200 kw (15,000 hp). The trend in metal mining during recent years towards mechanization and high-tonnage production methods has greatly increased ventilation requirements. The flow of air must quickly dilute and carry away diesel exhaust fumes, dust created by mining operations, and the fumes of the explosives used in blasting. Mechanical ventilation is required to obtain the necessary volume and control, as natural ventilation pressures alone are, for the most part, inadequate and unreliable. In the event of a mine fire or other needs, close control of ventilation is essential. There are two unique heating systems presently in operation at Inco: Creighton Natural Heat Ex- changer and Stobie Ice Stopes.

Jan 1, 1989

By S. Ross, M. Mayhew

"Kirkland Lake Gold introduced battery equipped vehicles (BEVs) at the Macassa Mine in 2011. The fleet of underground BEV haulage trucks and loaders has grown over the years to over 30 units, the world’s largest, currently handling approximately 80% of the daily production tonnage. The inflow and outflow of air occur through a limited number of relatively small openings, which limits the air volume delivered to the underground workings. In addition to improving air quality, the reduced heat load generated by the BEV (when compared to diesel equipment) had a significant positive impact in the workplace. The use of BEV for material handling has enabled increases in production that would not have been possible using diesel equipment.INTRODUCTIONMacassa mine was developed as a track-drift access mine, with the most recent shaft (#3) sunk in 1986. A new mining complex, the South Mine Complex (SMC) was discovered below the 5025 foot elevation south of traditional mining areas, and the majority of mining now occurs in the SMC. The discovery of that zone has led to an internal ramp which is used to access the SMC and haul ore to #3 shaft.The amount of airflow that can be moved through the mine is limited by the existing infrastructure to surface. This amount was recently increased to near its practical maximum from 118 CMS (250 kCFM) to 151 CMS (320 kCFM).Both diesel and electric equipment are used at Macassa. Tethered Load-Haul-Dump Machines (LHDs) have been replaced with Battery Electric LHDs, due to their increased mobility and depth of the mine. Battery trucks continue to replace locomotives to transport both ore and waste to the shaft, as mining has transitioned from tracked levels to trackless level and haulage has transitioned from horizontal levels to an inclined ramp.EQUIPMENT FLEET AT MACASSAMost of the primary material movers utilized at Macassa Mine are battery operated. As the mine goes deeper the battery technology will continue to be critical to the success of the operations. With over 300,000 hours of proven operation success, the battery technology and equipment will continue to be a major part of Macassa’s future."

Jan 1, 2019

By Nixon TR

The Australian Coal Industry Research Laboratories Ltd. (A.C.I.R.L.) MINVENT computer program can be used to simulate existing and projected colliery ventilation requirements. New collieries can be planned using a database of ventilation parameters which were ascertain- ed by A.C.I.R.L. surveys at selected collieries in N.S.W. and Queensland. Several techniques are used in both the formulation of the database and in the evaluat- ion of a ventilation system, prior to analysis by the MINVENT program. The analysis of a ventilation system requires the measurement of air quantities, pressures and hence airway resistances. All resistances are calculated at standard air density of 1.205 kg/m3. Air densities are derived from barometric pressure and wet and dry bulb temperature readings. Airway frictional and shock losses, leakage through stoppings and overcasts, flow of air through regulators, face resistance and resistance of anomalous ventilation features are related to the typical Australian measured data presented.

Jan 1, 1983

By J Rowland

"This paper was primarily put together in order to demonstrate what are believed to be acceptablestandards, in relation to ventilation surveys and the subsequent model assembly process. Thiswas brought about by the fact that in many parts of the world it is regarded as acceptable to carryout ventilation surveys and then build and supply the client with a æstick fi gureÆ type ventilationmodel. Such stick models have arguably litt le use and a very short life span in the real world and isalmost impossible for site staff to maintain. Thankfully most underground coal mines in Australia strive to maintain a true replica model of their ventilation circuits and to keep them in a relatively good state. Given that these mines own and maintain the models, it is often seen as necessary to update or rebuild them. The level of survey detail required to do so is totally dependent on the end use of the data and the criticality of the accuracy of the data set, to the ongoing safety and viability of the business. Mine technical personnel should think clearly about the use and importance of the ventilation survey and subsequent report outputs required that will help them bett er understand their mines and bett er prepare them to manage their ventilation circuits, on an ongoing basis. This paper provides some guidance for Australian ventilation engineers so they may plan and execute this work æin houseÆ, should they rightly choose to do so. To this end, methods of data collection and circuit analysis required for surveys of a high order of accuracy are detailed. Also, some of the issues which are important when formulating a strategy to carry out the appropriate ventilation survey for the required purpose are summarised. As well, the major details that should be furnished within any survey and some survey/report outputs and/or omissions, which are clearly not acceptable, are highlighted."

Jun 1, 2012

By B. S. Prosser, K. G. Wallace, A. Akansobe

"This paper describes a ventilation project at the Wassa gold mine in Ghana. Golden Star (Wassa) (GSWL), a subsidiary of Golden Star Resources, owns and operates the mine. Golden Star holds a 90% interest in GSWL, while the Ghanaian Government holds the remaining 10% ownership, earning a 5% royalty on the gross revenue of GSWL’s gold production. Construction of the underground mine began in mid-2015 and pre-commercial production started in June 2016. Commercial production from the underground mine was achieved in January 2017. This paper describes the ventilation studies performed to support the initial development and production at the mine. The initial ventilation design included four, parallel surface exhaust fans. Future designs will include booster fans, new primary fans, and additional connections to surface. The paper describes the long-term ventilation planning goals and expectations as the mine achieves a production of 4,000 tpd with truck haulage to surface.INTRODUCTIONThe Wassa Gold Mine is located in the southern portion of the Ashanti Greenstone Gold Belt in Ghana, northwest of Tarkwa as shown in Figure 1. The mine has been in production as an open pit since 1998, with some minor disruptions, but the surface minable reserves have become exhausted and the mine started a transition to an underground operation in 2015. The underground mine was initially developed with twin decline accesses extending from the base of the open pit to the mining areas. The mining method selected was sub-level open stoping with cemented rock backfill. The original production level for the mine was 2,500 tpd with ore and waste transported by trucks hauling in the ramps to surface. In 2017 the production goal was set to increase to approximately 4,000 tpd. This resulted in an increase in the truck haulage fleet in addition to a significant increase in ventilation requirements. This paper describes the ventilation upgrades at the mine as it transitioned from a surface to an underground operation and the adjustments the ventilation system needed to make in order to accommodate a significant increase in production"

Jan 1, 2019

By C. K. Kocsis, S. Hardcastle

Mine ventilation, requires electricity to operate the fans and fossil fuel for heating. Typically, this accounts for approximately 40% of the overall underground energy consumption. This is considerable, and one of the major causes of this expense is that most mine ventilation systems are designed for the "worst-case-scenario" with respect to ventilation demand, which is commonly dictated by diesel equipment usage. Once designed, mines tend to operate their ventilation system at this peak level despite their exceeding day-to-day development and production needs due to lack of appropriate ventilation controls. In underground metal mines, TeleminingTM, which includes the tele-remote operation of mobile development and production equipment from surface, will change the mine design criteria including its support infrastructure such as the ventilation system. With the removal of machine operators to surface control rooms, conventional ventilation systems designed to dilute and remove pollutants can become redundant. Depending on the ultimate need for ventilation, its cost in automated mines with tele-remote equipment operated from surface will be lower than the cost of ventilation in conventional mines. These cost savings, which could be significant, would not only come from the ability to reduce the amount of ventilation in the mine, but also through the capacity to automate its distribution. This paper provides an indication of the new airflow requirements in stopes and dead-end developments for the tele-remote and automated mining processes based on climatic modelling. Furthermore, this paper makes a cost benefit analysis by comparing the ventilation system operating cost of a conventional underground metal mine based on the mobile diesel powered equipment design criteria with the newly redesigned ventilation system operating cost of an automated mine based on the "heat management" design criteria.

Jan 1, 2002

By R. Stach, S. Gola, P. Zgrzebski, K. Soroko

"The future of Polish copper mines KGHM Polish Miedz S.A. will be associated with mining at depth. At present, technologically advanced measures are being introduced to minimize the adverse influence of the environmental hazards on people working underground. Polkowice-Sieroszowice mine is the only mine in Poland where mining takes place in copper and salt deposits. On the basis of the current and anticipated methods of ventilation of a selected ore deposits the paper will analynze a number of solutions enabling planned mining of copper ore deposit, while minimizing the impact of natural aerological hazards in working areas. INTRODUCTION The future of copper ore mining, carried out by KGHM Polska Miedz S.A., will be based on mining from continuously greater depths (Butra, 2015). It is forecast that this will be accompanied by an increasing climatic hazard, resulting from an increase in the original temperature of rocks of more than 45°C as well as gas and geodynamic hazards (Soroko, 2015; Andrusikiewicz, 2015). Due to the safety of underground teams, a need arises to develop methods eliminating the adverse impact of the natural hazards, down to a level enabling the mining activity to be carried out on an industrial scale while maintaining favourable economic parameters. Current depths of the copper ore deposit being developed are effectively verifying the technical methods and measures employed to date for eliminating the natural aerological hazards. Amounts of air supplied to mining areas, with lengthy transport routes, are becoming insufficient for miners’ temperature safety, whereas increasing the power of cooling air-conditioning stations for cooling the air undermines the economic legitimacy. However, along with the temperature hazard, a significant problem at the current depths is an increase in gaseous occurrences in the headings’ areas. The concentrations of natural harmful gases found, even with the values below the permissible concentrations, in the case of limited amounts of air and/or low airflow rates, may pose a considerable danger to the workers. The hazards referred to are currently the major factors determining the advance of headings, above all in mining sections, being the outcome of geological structure and depth of lying of a deposit. However, at the current depths of mining minerals from deposits, room-and-pillar mining systems employed also have a decisive impact on the increase in natural aerological hazards."

Jan 1, 2019

By A Llewellyn, M Varvari

The ventilation circuit at the FrogÆs Leg Mine was originally designed to permit mining to progress down to 440 m below surface at a maximum production rate of 500 kt/a, as per the feasibility study. The FrogÆs Leg resource has now been defined down to 640 m below surface at a maximum production rate of 750 kt/a. In order to allow for this increase in production depth and tonnage, it was necessary to upgrade the ventilation circuit.This paper outlines the upgrades to the ventilation circuit that were undertaken and the underlying rationale behind them.CITATION:Llewellyn, A and Varvari, M, 2013. Ventilation upgrade at the FrogÆs Leg Mine - Case study, in Proceedings The Australian Mine Ventilation Conference , pp 95-102 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By Eugie Kabwe

The increase in depth of mines due to the depletion of surface deposits leads to unsafe tunnel construction and overall ore extraction. This is due to tunnel instability associated with the surrounding rock mass’s ability to exhibit creep that occurs over time. However, the explicit description of this mechanism using conventional constitutive models has proven to be difficult and inadequate. Hence, this paper presents an integrated viscoelastic viscoplastic visco-damage model with the Duvaut-Lions function. The presented model is calibrated by experimental data to determine the viscoelastic viscoplastic and visco-damage parameters. It is further implemented in a finite volume numerical code and verified on an experimental scale by numerical modeling of a cylindrical specimen. It describes the 3-phase creep mechanism perfectly as compared to the inbuilt conventional integer-order derivative model. Results from the conducted verification show that it can successfully be employed to describe the long-term behavior associated with the creep mechanism.

May 16, 2021

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

A direct comparison has been undertaken between laboratory wind tunnel experimentation and computational fluid dynamics simulation of a 3D manufactured analogue for a body of fractured broken rock, created with CAD/CAM techniques. Detailed descriptions of the ?design? of the analogue (using a discrete element analysis multi-body simulator), its manufacture (using computer aided design and 3D printing technology) and the laboratory experimentation (inserting the physical analogue into a laboratory scale wind tunnel) are presented. The agreement of the results of direct experimental observations on the manufactured analogue with the values from CFD simulations of those experiments justifies the utilization of a CFD environment for the practical investigation of geometric factors controlling air flow and heat exchange in complex assemblages of broken rock blocks. The ultimate goal is described, that of developing functional relations between bulk properties of such assemblages (such as their porosity and bulk density) and the low-level geometric factors that dictate the air flow behaviour, such as the equivalent perimeter length of the cross-sectional area available for flow, or average flow path tortuosity. A practical application area of the work in the mining context is also described; equivalent continuum air flow and heat transfer constitutive models developed on the CFD tool from such functional relations are useful in characterization of seasonal heat storage in large scale bodies (approximately 1 km3) of broken rock.

Aug 1, 2013

By Suthan Pooranampillai

Verification of drilled shaft resistance is primarily obtained through the use of different load testing methods. Procedures utilized include conventional top down static loading, the Osterberg load cell (O-cell) test and dynamic tests such as the Statnamic method. The O-cell test provides a means of obtaining separately the base and side shear resistance behavior of drilled shafts (cast-in-drilled-hole). Alternatively, the Statnamic load test method enables the engineer to derive base and side shear behavior separately, based on measurements of load, accelerations and strains along the length of the shaft. However, due to time and cost constraints these tests can only be performed on selected shafts within a project. Post grouting of a drilled shaft base embedded within a cohesionless material, with a low mobility compaction grout, will essentially pre-load the shaft base soil against the side shear and self-weight in much the same manner as an O-cell load test (when the load cell is placed within the base vicinity). Therefore, successful post grouting of a drilled shaft would enable verification of both shaft side shear and base resistance simultaneously on each and every shaft it is carried out on. Additionally, such post grouted shafts display stiffer load-displacement response during subsequent downward, superstructure induced, loading compared to ungrouted shafts. Verification of resistance on each and every shaft through the use of post grouting will allow an increase in resistance factors (reduction in safety factor) used in the design. Two 6 ft. diameter drilled shafts were constructed in Fredonia, WA, for WSDOT, each with an approximate length of 52 ft. The shafts were terminated within medium dense poorly graded silty sand. Statnamic load testing of the shafts indicated maximum derived static side shear and base resistances of 2545 kips and 507 kips (1.6 in. displacement) for shaft One and 2466 kips and 212 kips (1.4 in. displacement) for shaft Two. Shaft Two was subsequently grouted, with a low mobility compaction grout. Shaft base mounted total earth pressure cells measured a maximum sustained pressure of 55.44 ksf during the compaction grouting operation. Shaft displacement reached 0.65 inches in the upward direction at termination of grouting. Comparison of grouting data with initial load test information indicates that properly instrumented post grouting verifies shaft base and side shear resistance. In addition, these grouting induced resistances were much higher than design values supplied by the engineer using conventional resistance factor design. Large scale laboratory testing also shows that base grouting verifies higher soil resistances than permissible in conventional design.

Jan 1, 2010

By Massoud Hassanabadi

Filtration using Ceramic Foam Filters (CFFs) is a method widely used to separate inclusions from molten aluminium. In the present work, the specific permeability and form drag coefficients of nominal 50 mm thick commercial Al2O3- based CFFs, of grades 30, 50, 65 and 80, have been calculated from pressure drop experiments using high (60–500 mm s−1) and low (0.2–10 mm s−1) water velocities. Moreover, 2D axial symmetric Computational Fluid Dynamic (CFD) models have been developed, using COMSOL Multiphysics® to validate the experimental results. The empirically obtained values were defined as global parameters used to model the pressure, as well as the velocity fields in the water pipes and in the CFFs. The modelled pressure drop over the filter thickness for the high water velocity experiments showed < ± 1% deviation from the corresponding experimental results for all CFF grades. Moreover, the developed model also showed good agreement with the experimental results obtained from the low water velocity experiments, where the deviation of the pressure drop for the CFF samples of grade 30, 50 and 65 were ≤ ± 4.6% and for CFF samples of grade 80 ≤ ± 13.4%.

By Julián Andrés Ortiz González

Este estudo apresenta novos resultados que comprovam a confiabilidade e a repetibilidade das medições de cargas de abertura de trincas de fadiga obtidas em estudos anteriores [1,2], que foram usadas para questionar a hipótese proposta por Elber em 1970 de que a força motriz das trincas é a gama efetiva do fator de intensidade de tensões (?Kef). Para isto, dois corpos de prova DC(T), um fino com 2 mm e o outro grosso com 30 mm de espessura, foram usados em ensaios de propagação de trincas por fadiga sob ?K e Kmax quase constantes, para simular condições dominadas por tensão ou deformação plana. Medições redundantes de ?Kef foram feitas usando uma série de extensômetros colados ao longo do ligamento residual à frente da ponta da trinca, por outro extensômetro colado na face traseira do DC(T), e por um sistema independente de correlação digital de imagens (DIC), que mede o campo de deslocamentos na face do espécimem. As cargas de abertura medidas pelos três sistemas independentes foram similares, comprovando assim que suas variações significativas observadas durante o crescimento da trinca são metrologicamente confiáveis. Este resultado comprova que a propagação daquelas trincas por fadiga não foi controlada por ?Kef. As consequências desta conclusão são detalhadamente discutidas neste trabalho.

Aug 17, 2017

By Marcio B. Fonseca

Nickel-cobalt laterite deposits have become the focus of attention for hydrometallurgical processing. Following the lessons of the second generation high pressure acid leach (HPAL) projects in Western Australia other Ni-Co laterite projects are now evaluating potential HPAL projects with a rigorous integrated approach that begins with geological modeling, resource estimation and metallurgical studies. The Vermelho nickel-cobalt laterite deposit has been under exploration and study for several years with investigations of various metallurgical processes. Recent HPAL studies have indicated that the nickel and cobalt laterite at this deposit is amenable to upgrading by silica rejection followed by pressure leaching. These studies have required a detailed geological investigation to generate a new resource model. The recent development of a sophisticated geological model integrated with a multi-element resource estimation for this complex tropical nickel laterite deposit in northern Brazil provides an example of the contribution of geology at the critical project stage where process technology decisions are made on relatively small samples of the total resource.\ Keywords: Ni Laterite, Geological Modeling, Resource Estimation

Jan 1, 2004