Search Documents

By J. Duncan Crone

"A test surface Pulse EM(PEM) survey over a plunging massive sulphide lens, located in the Snow Lake area of Manitoba, has shown that it is possible to detect the body to a depth of 300 metres. Another surface survey in the Athabasca basin of Saskatchewan, clearly outlined a large, basement graphitic zone below 450 metres of sandstone cover. Deep detection of these conductive bodies was achieved by energizing large volumes of ground with a strong transmitted EM field. Such large fields also energize all other conductors present in the exploration area. Both of the above survey results indicate that more than one conductor is present. In such cases, detailed field coverage is required for accurate interpretation, and interpretational procedures that assume simple geometrical shapes should be applied with caution. In all cases geological and geophysical information should be coordinated in detail. The first test drill hole still has a high risk of missing the deep conductive body and two or three holes should be budgeted per target.Borehole Pulse EM surveys are now routinely used to help zero in on deep conductive targets. They are also proving effective in development drilling programs by outlining the edges of conductive bodies. The results of surveys from northern Quebec illustrate how they may provide more accurate shape and tonnage estimates."

Jan 1, 1985

By P Mikula, R Geranmayeh, R Carlton, M Ferguson, R Whiting

The concept of using specially designed slot blasts to mine through stress abutments that intersect faults, while controlling fault-slip seismicity, has come of age at Mt Charlotte Mine. Due to the high and adverse stress field and the presence of major faults, the mine is vulnerable to significant fault-slip seismicity. As mining proceeded, advancing stress abutments around various mined areas encroached on several major subvertical faults. If the sequence formed a diminishing pillar between stope and fault, the removal or failure of that pillar daylighted the fault, and often resulted in significant fault-slip seismicity. A new strategy called ‘Tight Slot Blasting’ (TSB) was developed to restrain or dampen this style of fault-slip movement. The TSB has geometric similarities to a conventional cut-off slot used to create stress shadows, but its function is different. Its objective is to trigger and control a sudden shift of the stress state on a fault from an initial stable state, through an unstable transition, to a second stable state. A TSB firing advances a long tall narrow slot through a stressed abutment between a stope void and a nearby fault, using a rapid blast with a low swell ratio, so that the slot substantially and rapidly fills with blasted rock fragments. During the blast process, the stressed rock is rapidly removed and transformed into the fragmented rock fill in the slot. The strategy deliberately allows a fault-slip episode to manifest at a chosen time and place. The tight-packed broken rock in the slot performs an essential shock-absorbing function by controlling the slip amount and rate on the fault, while at the same time the fill becomes compacted by the movement. This controls the dissipation of fault-slip energy, and greatly reduces the seismic response in time and space. A small closure across the slot occurs, with consequent relaxation and destressing of the adjacent rock mass. Stress monitoring data shows that slot creation lowers the abutment stress in the nearby rock mass, while the newly placed fragmented rock fill acts as a shock absorber, providing considerable resistance to substantial fault-slip movement that otherwise could deliver a significant seismic event. First used in 2007, the strategy has been refined to become a routine specialised practice for management of seismically hazardous situations at Mt Charlotte, with 12 successful TSBs conducted to date. Despite mining through multiple high stress abutments, seismic reactions have not exceeded ML 2.1 with any TSB firing, all remaining below the site tolerable maximum of ML 2.3. This paper presents an overview of the strategy, and five case examples of the strategy in critical stressed areas in July 2016, Sept 2017, Dec 2017 and two in Oct 2020. The strategy has successfully managed the seismicity and is expected to remain an essential part of the seismic management plan at Mt Charlotte Mine.

Nov 29, 2022

Effective control of respirable dust is one of the most serious problems associated with longwall mining in the United States. This report describes the development and laboratory testing of dust collectors for use on double drum shearers. Systems tested included: ? High Capacity Flooded Bed Scrubber ? Water Powered Extraction Cowls ? Water Powered Extraction Drums ? Water Powered spot Scrubbers. The systems were tested using tracer gas in a full-scale model of a longwall shearer face. This report provides a detailed description of the test facility, test methods, and system test results.

Jan 1, 1982

By G. W. McMahon

Following the Sago Mine accident, the U.S. Mine Safety and Health Administration (MSHA) asked the U.S. Army Engineer Research and Development Center to study several possible methane explosion scenarios in the Sago coal mine. The study used a 0.3-m (1-ft) resolution map of the mine to produce a 3-dimensional (3 D) model of a portion of the mine, including the sealed area where the explosion occurred. An advanced 3 D computational fluid dynamics (CFD) code was used to calculate the explosion pressures within the sealed area, on the mine seals and in nearby regions of the mine. Based on the best available information on methane concentrations and assumptions on homogeneity and on layering and mix composition, three separate initial conditions of methane-air concentrations and location were studied. This paper discusses the CFD modeling technique, the results of the calculations, the challenges of conducting this type of modeling and the advantages and limitations of CFD modeling of accident investigations of mine explosions.

Jul 1, 2010

By Xuemei Zheng, Aiyuan Ma, Guojiang Li, Tingfang Xie, Jinhui Peng, Libo Zhang

A new microwave roasting technology for the removal of Cl from zinc oxide dust is proposed in this paper. The effect of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The experimental results show that zinc oxide dust dechlorination rate can reach more than 95.66% and meet the requirements of wet smelting electrolysis when controlling the stirring speed of 60 r/min,roasting temperature of 650 °C, holding time of 30 min. In addition, the effect of roasting temperature and holding time on removal ef ficiency of Cl was most signi ficant. As a result, the Cl content was decreased without the risk of pollution. This makes it as a good choice for a more ecological treatment of zinc secondary resources.

Mar 1, 2018

By A. M. Milev

A simulated rockburst was conducted underground at Kopanang Mine, previously called Vaal Reefs No. 9 Shaft. The rockburst was simulated by means of a large blast detonated in solid rock close to a crosscut sidewall. The simulated rockburst involved the design of the seismic source, seismic observations in the near and far field, high-speed video filming, a study of rock mass conditions such as fractures, joints, rock strength etc. Knowledge of the site conditions before and after the simulated rockburst was also gained. Some of the important findings are listed below: ?Two areas of damage were identified on the blasting wall: (i) an area of high-intensity damage in which ground velocities of 3.3 m/s were recorded by an accelerometer, which was subsequently ejected in a block of rock, (ii) an area of low-intensity damage where ground velocities of 1.6 m/s were recorded by an accelerometer which remained on the tunnel wall. ?High-speed filming revealed rock fragments being ejected from the wall at velocities in the range of 0.6 m/s to 2.5 m/s. The measurements were taken in the area of low-intensity damage. As planned, no gas pressure was directly involved in damaging the wall of the tunnel. ?The attenuation of peak particle velocities for the main blast in the near field (6 m to 30 m), as a function of distance R, was found to be proportional to R-1.7. ?The simulated rockburst was recorded as a local magnitude ML= 1.3 by the Klerksdorp regional seismic network. ?Peak particle velocities from nearby blasting, recorded on the tunnel wall after the simulated rockburst, were about six times greater then peak particle velocities recorded from the same source area before the simulated rockburst.

Jan 1, 2001

By Jürgen. F. Brune, CLAIRE STREBINGER, ADITYA JUGANDA, Gregory E. Bogin Jr

The abstract highlights the risk of methane gas explosions in underground coal mines and the potential of computational fluid dynamics (CFD) modeling to simulate such events and assess their impact on mine ventilation. The study focuses on developing CFD models for large-scale explosions in longwall mines, specifically simulating methane gas explosions resulting from face ignition during coal cutting. The research demonstrates the integration of a combustion model into a longwall mine ventilation model and shows how the availability of explosive gas mixtures significantly affects flame propagation and explosion pressure.

Mar 27, 2022

By P Collier

From 1972 until 1989 when operations were suspended Bougainville Copper Limited (BCL, owned 53.58 per cent by Rio Tinto Limited) operated a large open pit mine and processing facility at Panguna on Bougainville Island, Papua New Guinea producing copper concentrate containing significant quantities of gold and silver.BCL has a stated vision of recommencing operations at Panguna. In 2008, Rio Tinto, on behalf of BCL, conducted a multi-disciplinary study to assess the technical and financial viability of redeveloping the Panguna operation. One of the key outputs of the study was a Joint Ore Reserves Committee (JORC) Code compliant mineral resource statement based on the existing block model and fundamental data, archived since mine closure. Historical data (including the resource block model and drill hole data) was recovered from computer archives by a former Panguna mine employee familiar with the various obsolete data formats, thus maintaining an unbroken chain of custody of the data by Rio Tinto since operations were suspended. No additional data were collected as part of this study.The extensive data and documentation archive facilitated a sufficiently detailed evaluation of the fundamental data and model to support an updated resource statement. Table 1 of the JORC Code was used to guide the model validation process.Reconciliation of blasthole and metallurgical plant data with the reserve model, indicated that the copper and gold drill hole composite database was significantly biased towards underestimation in several key domains due to a combination of the following: mineralisation loss during core loss, core loss (minor), vertical drill holes failing to intersect sufficient subvertical mineralised fractures and veins, drill hole spacing too wide, and variable diamond drill hole core size. The resource model evaluation was based on three material types (all previously mined at Panguna), that were defined based on cut-off grade and rock type parameters: direct feed ore – material for delivery directly to the plant, preconcentration and screening ore – subeconomic material beneficiated to produce fines of economic grade, and waste. Three pit shells and designs were generated based on three separate sets of economic parameters. These economic parameters were also used to assign material types to the block model. The three resulting models were then evaluated against the corresponding pit shells.Classification of the resource was approached conservatively due to the inherent bias in the drill hole data. Consequently only Indicated and Inferred resources were tabulated.The study highlighted the importance of maintaining detailed documentation pertaining to resource estimates and operational history, particularly reconciliation, and the value that can be added by a simple, low-cost data compilation exercise.

Aug 22, 2011

By Robert R. Perron

The U. S. Bureau of Mines is engaged in many diverse programs for improving mine safety. Of particular interest to the Bureau are new and improved means for minimizing the hazard of fire which can be initiated by prolonged low energy electrical faults on trolley line systems. When a high energy fault occurs on a trolley line, wherein the current exceeds the magnitude normally drawn by legitimate loads, such as locomotives, then the circuit breakers at close-by power rectifier sets trip. Tripping of the breakers not only protects the equipment at the rectifier sets, but also disconnects the energy source from the fault and thereby minimizes the fire risk. However, the fault current is frequently of a level substantially below that required to trip the overload breakers. When the fault is a substantial percentage of the set level of the breakers, the energy dissipated by the fault is frequently sufficient to clear the system by rapidly burning itself clear. Such a fault is often short-lived and does not present as serious a fire risk hazard as a prolonged, much lower energy fault, wherein the energy level is too low to clear the system. The breakdown of a trolley line insulator, in which there was a 15 to 30 ampere fault to ground, would represent such a fault or illegitimate load and a substantial fire risk.

Jan 1, 1975

By Elizabeth Gardiner

Tailings and water management facilities are integral components of mine and mill operations. They must be managed for the long term to ensure that safe and environmentally responsible stewardship is achieved. The Mining Association of Canada (MAC) has developed and published two manuals to provide guidance to mining companies on sound practices for the safe and environmentally responsible management of tailings facilities: ???A Guide to the Management of Tailings Facilities; and ???Developing an Operation, Maintenance and Surveillance Manual for Tailings and Water Management Facilities. The Guides were designed to help companies develop and implement tailings management systems that include environmental and safety criteria, to improve the consistency of application of sound engineering and management principles to tailings and water management facilities through their full life cycle, and to demonstrate this to regulators and the public.

May 1, 2003

By Galyn Rippentropp, Finn Erik Overlie

INTRODUCTION The wet shotcreting system utilizing steelfiber microsilica shotcrete with remote controlled equipment (The Robocon System) was developed in Norway 7-8 years ago. Norway was the natural origin for this system due to several factors. Almost 30% of all underground hydro-power stations in the world are located here. These projects created a need for high productivity shotcreting rigs for the rock support work in the caverns and in the connecting tunnels. During the period of 1976-1980, more than 1000 miles of tunnels were completed in Norway. Secondly, the utilization of microsilica in concrete was also developed in Norway due to a concentration of the world's ferroalloy p ants there. Robocon has presently placed approximately 110,000 m (150,000 cu. yds.) of this superior shotcrete, and has consequently an extensive experience in the shotcreting method. During a relatively short period of time (1975-1980), Robocon had a change from hand-operated, dry-process shotcrete to remote-controlled, wet-process shotcreting, because of improved productivity, reduced rebound, safer and cleaner working conditions. The introduction of microsilica and water-reducing admixture made it possible to produce wet-process shotcrete of high strength.

Jan 1, 1987

Typically, large volumes of data are collected during geotechnical investigations for mining projects but rarely is this done in a comprehensive manner that enables all aspects of the geotechnical environment to be evaluated. A geotechnical core logging process has been developed to record mechanical and structural properties of the rock mass. The method enables data for a wide range of rock properties and geotechnically significant major structures to be collected including rock strength, joint surface condition, fracture frequency and fracture orientation. The logging method is unique in that sufficient data is collected to enable the independent determination of all the major rock mass classification systems including rock mass rating (RMR), (Bieniawski 1976, 1989; Laubscher, 1990) Norwegian Geotechnical Institute (NGI) tunnelling quality index (Q) (Barton, Lien and Lunde, 1974) and geological strength index (GSI) (Hoek, Kaiser and Bawden, 1995). The logging system has been specifically developed to allow better and more precise appreciation of rock mass and structural conditions across the project area thereby optimising the use and application of the available geotechnical data and improving confidence in the outcomes of geotechnical investigations. This paper describes the core logging process with case examples showing how the logged data can be used for underground and open pit mine design.

Nov 25, 2010

By G. Danko, R. Tiwari, J. Knowles

Many excavation and loading tasks require equipment operators to simultaneously coordinate the motion of multiple machine links, in order to achieve complex tool trajectories. Efficiency, ore selectivity, and machine wear, are all affected by the skill level and attentiveness of the operator. A software-based kinematics reconfiguration system designed to assist operators with various tasks has been implemented on a small experimental excavator using our new differential control architecture. Kinematics transformation and feedback control algorithms are being developed and tested using computer simulation, and the results implemented on the experimental excavator. Several task-specific kinematics transformations, including a virtual revolute-to-Cartesian machine reconfiguration and computer-assisted bucket steering and stabilization have been successfully tested. Progress, challenges, results, expected benefits, and planned work are described.

Jan 1, 2006

The Greymouth Coalfield contains New Zealand's greatest known resource of bituminous rank coal. The coals are of very high quality, with low ash and sulphur contents and a range of other properties that makes them desirable for a wide range of uses. In fact only a few producers around the world today can offer coals with such exceptional properties. This suggests that Greymouth coal has potential as a premium export trading commodity. These assertions have been largely confirmed by a comprehensive exploration drilling programme funded by Mines Division û Ministry of Energy between 1979 and 1984. The program, forming part of the NZ Coal Resources Survey, was carried out under contract by Lime and Marble Ltd. The drilling of 49 deep, predominantly cored, holes at 1000 m intervals over the coalfield has generated a vast amount of data. It has shown the existence of three major potentially minable coal deposits containing 233 x 106, 33 x 106 and 15 x 106 tonnes of coal in ground. Investigations have at this stage only identified targets and these estimates represent 'in ground' resources, not recoverable reserves. Recent geological studies as well as past and present mining have clearly highlighted the problems posed by the complexity of the coalfield geology. The coalfield lies within a mobile zone in the earth's crust known as the Paporoa Tectonic Zone, which has been active from at least mid-Cretaceous to the present time. Currently this factor poses the greatest obstacle to the determination of mining possibility of the, defined deposit and ultimately will strongly influence any future mining development. The Greymouth Coalfield has, however, had a long and eventful mining history spanning the last 120 years, where 32.5 x 106 tonnes of coal has been won from over 100 mines. In spite of the problems facing development, the large quantities and exceptional quality of the remaining coal will act as a strong inducement to persevere with this difficult but potentially valuable resource.

Jan 1, 1985

By Mathew Cook

Technological developments in Distributed Fiber Optic Sensing and improvements in both hardware and software have allowed fiber optic sensing systems to be deployed in a variety of applications such as pipeline leak detection, perimeter security monitoring, and power cable real time thermal rating. Recently, there has been a larger adoption of monitoring of conveyor belts in so called Conveyor Health Monitiring Systems (CHMS) within the mining and bulk material handling industries to identify idler conditions on an ongoing basis. Several attempts have been made to institute sensing capabilities into conveyors with mixed success. However, recent breakthroughs in modeling, installation methodology, and technology, as well as increased understanding of application and industry requirements, have allowed the technology to be deployed at both experimental and commercial scales. This paper summarizes the application conditions and requirements, design considerations, methodologies used, the outcomes achieved, the logistical and field considerations, and the future possibilities of the use of this technology in CHMS using Distributed Fiber Optic Sensing.

Feb 22, 2026

By P. J. Noakes

Remote and isolated, located in a frigid, hostile environment, the Black Angel mine in Greenland had to create a warm social environment which would help attract and retain a stable work force of miners and support staff. The high cost of personnel turnover plagues many mines and, when the mine is inside the Arctic Circle, accessible by helicopters which are highly vulnerable to unpredictable weather conditions during the long, dark winters, the potential costs of personnel turnover become critical factors in the success or failure of the mining venture. Manpower planning should start from the date the engineers begin the technical design of the new mine. The plan should include provisions not only to ensure an adequate, skilled work force, but also to ensure a stable work force of people who are happy enough in the mining environment to want to remain, take their vacation and return to work at the mine. The skilled work force was assured with training courses of four months, designed to produce highly specialized underground workers from unskilled Danes and Greenlanders supported by trained Swedish and other Scandinavian miners. The stable social unit was assured by plans the primary attribute of which had to be flexibility. The accommodation changed from shared accommodation with communal washroom facilities to single accommodation with private washroom facilities. A recreational director was hired to help the workers make use of elaborate recreational facilities. A closed-circuit TV and radio system was installed to operate as a private broadcasting system using taped programs originally broadcast on European TV networks or developed by the mine personnel themselves. The liquor rules were changed and the mine manager became a licensed innkeeper responsible for the orderly operation of the Black Angel Bar in accordance with the Danish laws governing the services of a public bar. The result is a relatively stable work force. Some 35% of the people have more than two years' service with the company, Greenex A/S, and some 62% complete 10 months of service.

Jan 1, 1978

By Vladimir J. Ovdenko, Sergey N. Lazarenko, Evgeny L. Schastlivtsev

The term sustainable development shortly appeared in international use in the run of UNO Environmental Protection Conference held in Rio de Janeim in 1992, bears the concept, that evolution process ( associated either with a region or society) should provide mutual interests concern in three aspects - environmental, economic and social ones, admitting as well the fact , that environmental protection should become an integral part of each process and cannot be regarded separately. In this connection it seems quite reasonable to employ the principal of sustainable development, while creating the model of industrial mastering the territory constraint lands viewing their future, for a example, in rich mineral deposit's development. In Kuznetsk coal basin in Russia ( west Siberia) the development of a big coal deposit Erunakovsky is now being underway. The major part of coal will be mined with open cast method, resulting the number of local environmental adverse impacts' occurrence. In such a situation mastering of sustainable development model is given the top priority, demonstrating the essential result of its application in a form of possibility to define the best correlation between economically expedient and environmentally tolerable loads during coal mining. The given paper is an attempt to work out the main principals to approach the creation of sustainable development model in regard of the definite region case. To simplify the presentation of employed approach's main idea, the given below accepts as its component only one of many actually existing environmental profiles, that define mining pro- cess impact on environmental situation -the size of infringed (de- graded) lithosphere surface. Basically, the actually existed correlation between spheres. grounding the model of sustainable development - economic, environmental and social- is given in a form of nomogram under Fig.1. On the presented graph the prognostic values of broken lands relative extent within Erunakovsky boundary ( to be compared with total region area taken as 100%) are arranged on axis x". Axis "y- demonstrates the main values associated with complete economic background, making the intrinsic part of the principal for sustainable development, i.e. annual coal output for the given area. It's top, used in assessment value relates to actual showings implied for the study region project and quantifies 60 min. tons. While regarding the social facet of principal for sustainable development, the applied mode to separate social issues into two types - one profiling a welfare standard of living and the other. pertaining the way environmental situation contributes to the degree of &ologica-1 comfort in people's living was defined as the most expedient and the most adequate in the matter of reflecting the actual terms of vital activity of the society. In accordance with the cited above the economic level showings are plotted on the graph on "-x” axis, while "-y" one obtains the values associated with the point of ecological comfort presented in conventional units. For the maximum possible conventional point of living (corresponding in nomogram to 1.0 value) a welfare level secured with industrial region economic activity revenue was assumed in case the top planned annual amount of coal is delivered ( 60 min. tons). While studying the index of public economic welfare, environmental conditions corresponding level in its original state i.e. prior to any industrial work carried in the region, was adopted as its top possible conventional rating (1.0). The given nomogram displays the integrity of x-f(y) type interrelations plotted on the basis of four separate dependencies, precisely a) the size (area) of infringed earth's surface as a function of coal output in the region; b) subordination of ecological comfort of people's living to the degree of lands infringement; c) interconnection of economic and environmental components of people living; d) interconnection of economic level of people's living and the amount of coal mined in the region. Linked to a single unit, these separate plain dependencies create, as seen from the graph, a more intricate system of bonds, that affords during defining or changing this or that system parameter to secure undergoing changes, that occur to other parameters of the system. The mentioned reason made it possible to consider and drive to mutual conformity ( as far as it is possible) all parameters values for the defined system's relations, that in their turn indicate the concern of other aspects of a sustainable development principal. According to the graph, in order to get not more than 50% of infringed land left after the deposit's mining, it is advisable to ex- tract not more than 40 min. tons of coal annually, gaining in this case the level of ecological comfort for living in the amount of not

Jan 1, 1996

By F. G. Schwartz

The Bureau of Mines developed a rapid and precise method for predicting storage stability of motor gasolines. This method resulted from the investigation of many analytical techniques as well as a study of fuel composition and fuel component gum-forming mechanisms. The first section of this bulletin discusses the development of the prediction test through its several phases, including revision of the standard 110° F storage test; attempts to develop a modification of the ASTM D525 induction bomb test; and the ultimate abandonment of this procedure with the adoption of the 16-hour oven test that was both precise and rapid. The second section comprises a discussion of further studies of fuel com- position, including the reactivity of certain sulfur compounds and hydrocarbons to form gum. The compositions of various gums and inorganic deposits are reported in terms of elemental analysis and spectroscopic examinations. The reactions of tetraethyllead with selected hydrocarbons are also reported.

Jan 1, 1972

The efficiency of a coal mine ventilation circuit is usually measured by the ratio of the sum of the face quantities divided by the quantity supplied by the fans. Other types of systems use the power delivered to the power supplied to measure efficiency. This paper argues the case that the current measure may be inadequate and that by also looking at the power ratio, ventilation may be better managed. Problems associated with failing ventilation systems would be highlighted earlier so that crisis management could be avoided.

Jan 1, 2009

By Hugh Thompson

In mining today, planning is of paramount importance, even more so when one considers that the business margins are reducing, requiring the evaluation of diverse alternatives for the optimal use of scarce resources. Additionally the capital required to approve some projects demands the best planning possible. Modern planning requires that all of the aspects of the business be represented, and not just the planning of the extraction in an isolated form. In order to carry out integrated strategic planning in the mining business one needs to have implemented a culture within the organisation that allows the business to be understood as a interelated system of processes. These processes must be co-ordinated so that they interact properly between each other and so define an integrated plan that optimises the available resources and maximises the benefit to the company. This defined culture should consider the important variables of each activity within the processes, and its’ relevance to the strategic plan. In this sense, this paper shows an example of computer tools used in order to reach the described objectives.

Aug 25, 2002