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By Yoginder P. Chugh

The Department of Energy is presently sponsoring the development of automated miner-bolter machines in an effort to increase production and productivity in the continuous room-and-pillar mining sections. This study is concerned with the production potential of these machines in three different mine layouts. The Underground Material Handling Simulation (UGMHS) computer model was utilized in the study. The effect of variables such as bolt installation delay, shuttle car capacity, and equipment availability on production are analyzed.

Jan 1, 1979

By J. W. Oberholzer, C. F. Meyer

The increased use of continuous miners to extract thicker coal seams has necessitated the use of enhanced ventilation systems in the headings. Due to the increased face size, more ventilation is required to effectively dilute the liberated methane down to acceptable levels. If more air is directed to the face an increase in the entrainment of dust creates an increased potential for workers to be exposed to dust. To enable the ventilation systems to reduce the methane levels and the levels of the airborne dust the ventilation systems in the heading have to be carefully designed. The matter is made more complicated through the use of other ventilation methods like jet fans, air-moving sprayfans on the continuous miners and high capacity scrubbers on the continuous miners. To enable the design of a balanced ventilation system in seam heights of over five metres requires methods that consider the system in a three- dimensional manner rather than in a two-dimensional fashion. Through the use of computational fluid dynamics (CFD) coupled with appropriate methods of taking underground face ventilation readings these problems can be solved in a cost effective way. Using computer modelling, ventilation methods can be designed and assessed instead of using costly underground trials to test the alternatives. Use of this system has led to a higher level of ventilation design as well as a more effective method to combat the health and safety hazards in coal mine headings.

Jan 1, 1995

By Timothy J. L. Haley

The population of the Rhondda underwent a spectacular rise as energy requirements increased in the mid-nineteenth century. The rapid expansion in the demand for coal transformed the population from a few hundred sheep farmers in the eighteenth century, into a thriving coal-based economy of some 168,000 inhabitants in 1924. Cochrane (1958) put forward the idea that the differential migration of more healthy men from the Rhondda Fach during the period since the peak of population in 1924, had resulted in a respiratorily-impaired residual population. This idea was used to explain the reduced survival of miners & ex-miners aged 55-64 years from this valley as compared with a similar group from Leigh in England. Using the proportional hazards regression model of Cox (1972), a comparison is presented of the exact twenty-year mortality of migrant and non-migrant miners & ex-miners and non-miners from the Rhondda Fach. The analysis makes allowance for the pattern of migration throughout the twenty-year period and adjusts for the confounding influence of variables such as age, occupation, and category of Simple Pneumoconiosis. The results indicate that contrary to expectation, any effect of migration upon mortality is manifest only at higher ages. Furthermore, for these men, the migrants have worse survival than the non-migrants. Also, contrary to expectation in the light of work by the British Coal Board (Soutar et al, 1982) there is no evidence of increased mortality amongst men with category I simple pneumoconiosis. INTRODUCTION [The Background] In September 1950, the Medical Research Council's Pneumoconiosis Research Unit at Penarth in South Wales initiated a study of lung disease in the smaller of the two Rhondda Valleys - the Rhondda Fach. At that time, the primary interest was in assessing the possible role of pulmonary tuberculosis in the aetiology of the serious (complicated) form of coal-workers' pneumoconiosis, i.e. Progressive Massive Fibrosis. The Rhondda Fach is situated in South Wales, some 25 km north-west of Cardiff. It is a narrow winding river valley about 12 km long, and approximately 1 km wide. The name means Little Rhondda; there is a corresponding Big Rhondda - the Rhondda Fawr. Together, these valleys make-up most of the Rhondda Municipal Borough. Following the initial survey in 1950-51, there have been several follow-up studies of this population. In addition, amongst numerous other investigations to unravel the aetiology of coal-workers' pneumoconiosis, Medical Research Council teams studied various other (sample) population groups, particularly in the industrial areas of the adjacent Aberdare Valley, and in Staveley and Leigh in England. The agricultural areas of the Vale of Glamorgan in South Wales, and Annandale in Scotland were also studied.

Jan 1, 1993

By J. W. T. Ropkins, D. Allenby

The paper describes a technique by which large concrete boxes are unobtrusively inserted beneath existing highway and railway infrastructure to form new subways, culverts and under-bridges, thus avoiding the inconvenience and costs of disruption to traffic associated with traditional cut and cover techniques. A series of project examples, undertaken in the United Kingdom and United States, are used to illustrate the design and construction of the box structures, together with the technology required to control ground disturbance in the tunnel face and around the box, and the jacking systems necessary for box installation.

Jan 1, 2003

By Todor P. Stefanov

The thermal draught within ventilation networks of underground mines depends to a great extent on the shafts depths and degree of change of ventilating air density. When the topology and space orientation of a ventilation network are constant, the dynamics of thermal draught is determined mainly by the variations of the heat- and mass-transfer processes in the openings. This conclusion follows from the well known basic theoretical notions about the thermal draught-aerostatics and thermodynamics [1]. Quantitative evaluation about the influence of heat- and mass-transfer processes on dynamics of thermal draught could be made through: direct mine measurements, special experiments and with the aid of mathematical models. The first two methods produce sufficiently accurative results, however it is very difficult to perform such studies, particularly when these processes are evaluated within a large scope and multifactor aspects. Mathematical models of thermal draught allow to overcome easily these difficulties. The degree of accuracy of results, obtained by this method, depends to a great extent on the degree of approximation achieved by the model to the real heat- and mass-transfer processes. In this paper, with the aid of Bulgarian developed method, algorithm and computer program V WT-4 - for complex evaluation of ventilation parameters in active mine ventilation networks [2], the authors investigate some changes in the thermal draught. Basically, the method is an iterating evaluation of an open set of equations, which represents relationships between the following basic parameters of a mine ventilation network: [ ]

Jan 1, 1980

Traditionally, production volume has been considered the major determinant of cost. As volume increases, total cost increases but unit cost decreases. This concept has been so widespread in industry that many of the tools used to analyze costs are based on production volume as the sole measure of activity and driver of unit cost-fixed and variable costs, cost-volume-price and breakeven analysis, contribution margin, flexible budgets, and others. Clearly, volume is a driver of cost. It is important in both a tactical sense (to the manager at an operating mine) and a strategic sense (as one determinant to the firm's overall cost position). However, many other factors influence costs as well, even though they have not been studied to the same extent. For example, production managers know that their costs will be reduced if the workforce does not have accidents. Safety costs are to a large extent independent of volume. Other cost components increase as volume increases, such as some environmental charges. Some costs may or may not reflect volume changes. Maintenance, for example, may appear as either a fixed or variable cost, as can operating labor in facilities that are highly automated. In the strategic sense, where the firm is selecting a strategy to pursue competitive advantage and increased profitability, all costs are variable. This reflects both the strategic intent and the long-term time frame associated with strategic positioning. Tactically, on a month-by-month basis, some costs are essentially fixed. Cost driver analysis must therefore consider the relevant time frame.

Jan 1, 1999

By Flavio Moreira Ferreira

In mining industry, one of the simplest methods to smooth the standard deviation of a given ore controlled property is to build longitudinal blending piles. The effect of homogeneization is obtained due to the fact that an entire cross-section of the pile is reclaimed at each time. The variance of the pile output is the sum of the internal cross-section slice variance plus the reclaimed slice variance. While the first term is a tipical short-term parameter and is absorbed by the process, the second one may be or may not be absorbed. The goal of designing blending piles is to minimize the reclaimed slice variance. Conditional Simulation as described in this paper, is an alternative method to do it. It is devised to design longitudinal blending piles, taking into consideration economical, geometrical and statistical parameters of the ore to be blended, in order to estimate the resulting effect. It presents advantages in relation to other methods for its adaptability and flexibility in simulating pile performances.

Jan 1, 1992

By Hassan El-Shall, M. N. Ahmad, Ponisseril Somasundaran, C. R. Holland, G. M. Walker, N. Iles, R. D. Chandler, Regis Stana, B. Duddy, Patrick Zhang

Phosphoric acid is a major raw material for the production of ammonium phosphate (AP) that is used as an intermediate in fertilizer production. Impurities within commercial grade wet process phosphoric acid are important in producing a fertilizer granule with good handling properties. The impurities identified as being important are; iron (III), aluminium and fluorine-containing compounds. Results show that the viscosity of the AP slurry produced increases by increasing the amount of impurity in the acid. Bench scale tests have been successfully replicated on a plant scale leading to a better understanding of the composition of impurity levels within phosphoric acid required to produce a high quality, free flowing, hard, spherical and non-caking granular fertilizer.

Jan 1, 2002

By D. J. Collins

While the charcoal in pulp (CIP) process was introduced to the mining industry many years earlier, it did not gain widespread recognition until 1973 when Homes take Mining Company installed a CIP circuit at their Lead, South Dakota plant. Since then, a number of mills have been put into production which utilizes activated charcoal for the recovery of precious metals. One of these plants was the Jerritt Canyon mill which Freeport Gold Company commissioned in 1981. It was during the time that the author was employed by Freeport Gold Company that the ideas and concepts presented in this paper were formulated.

Jan 1, 1989

By Stanley Dempsey

Since its passage, the Mining Law of 1872 has been modified several times to meet the changing needs of America's society and economy. Despite the fact that it continues to provide an effective framework for a robust US exploration and mining industry, the mining law continues to be criticized in some quarters as outdated. Pressure to reform the Mining Law of 1872 has reached new levels in recent years. Many proposals for reform of the law have been introduced during the 1990s. None, though, have been enacted. The issue will not likely disappear and is certain to be raised during the 105th Congress. To provide a better understanding of the status of current congressional reform proposals, this article presents an overview of the major moments in the history of mining laws in the western United States - from the days before the 1872 mining law and the days following its promulgation, to the current dilemma over mining law reform. The future of the mining law is assessed as are the interests at stake for the modern mining industry. Mining before 1872 No discussion of the Mining Law of 1872 is complete without some historical background to provide an understanding of the origins of this unique law. There was plenty of mining activity on the public lands before the mining law was enacted. At first, the federal government's policy was to allow all miners to work freely on the public lands and to resolve disputes among themselves. In this "hands off" environment, miners operated according to laws they promulgated. These were based on previous experiences in Europe and Mexico. These "frontier codes" of groups of individual miners took the form

Jan 1, 1997

By K. Bragg

During the last several years considerable discussion has taken place on the long term aspects of uranium tailings management. These discussions have centered around a variety of topics which in turn lead to a variety of opinions. In order to come to grips with the various differences of opinion and points of view, the Atomic Energy Control Board has decided to prepare, as an interim measure, a list of proposed close-out criteria for uranium tailings management facilities. It is important to keep in mind that the criteria set out in this paper are proposals and are intended to initiate a continuing dialogue between the uranium mining industry and the various regulatory and government agencies. It is envisaged that this dialogue would continue for a period of from six to twelve months after which some final form of these criteria would be issued and applied to the active uranium mining facilities. In attempting to understand the reasons why the Atomic Energy Control Board has decided to propose these criteria now instead of at some future point in time, it is necessary to look at a number of existing facts. One of the most important of these is that something in excess of one hundred million tonnes of tailings currently are placed in various tailings management facilities. Furthermore, the rate at which tailings are being deposited into such management facilities is on the increase and this increase is expected to continue over the next five to ten years. The management of these tailings is currently covered under the Mine Facility Operating Licences issued by the AECB. Implied within these licences and supporting documents leading to them, are requirements for the conceptual approach to be used at abandonment. There is however, no current requirement for a detailed study on the engineering or financial aspects of such abandonment procedures. This is a gap which the Board feels must be addressed. There are, at this time, various initiatives underway both in Canada and within the international community which are attempting to address the problems and concerns of the very long term management of tailings. For example, current research in Canada which is composed of two components, one by the AECB dealing with purely regulatory aspects and a second major coordinated program under the direction of the Department of Energy, Mines and Resources and in particular by CANMET is going to deal with the technical problems. On the international scene

Jan 1, 1980

By Edmond O’Donovan

Selection of conveyor drives is an area of great confusion that frequently leads to poor system performance or overcapitalization. Many papers have dealt with the performance characteristics of different drive types, but users have often found that this only leads to further confusion. This paper presents the drive requirements from the "conveyor's" point of view. The drive requirements of different classes of conveyors are examined to illustrate why some drive types work well in certain situations but poorly in others. The appropriateness and shortcomings of different drives are examined in this context, along with the recurrent issue of load sharing.

Jan 1, 2000

By V. C. Rogers, K. K. Nielson

INTRODUCTION The potential health impact from uranium milling operations is mainly associated with long-term releases of radioactive contaminants from the mill tailings.(1,2) The major mechanisms for mitigating these potential releases focus on increasing the tailings containment with the addition of migration barriers such as thick earthen covers and clay liners. Some limited investigation has also focused on reducing the radionuclide source terms. This alternative approach has some desirable features, but stringent cost requirements are placed upon source removal methods in order for them to be economically favorable. A cost effectiveness evaluation is presented herein, in which costs for containment methods are used to establish maximum cost guidelines for the source removal methods. The 230U decay chain, shown in Figure 1 contains the radioisotopes of major concern, 230Th, 226Ra, 222Rn and its short-lived alpha-emitting daughters, When the uranium is removed in the milling process, these isotopes, which are normally not removed remain in the tailings solids. The general pathways to the environment from uranium mill tailings are depicted in Figure 2. The dominant pathways are radon to the atmosphere and radium and thorium to a groundwater aquifer. The magnitude of the contaminants released into these pathways can be characterized by the following parameters: 1. The 230Th and 226Ra content. 2. The emanating power for radon. The fraction of radon generated that is free to migrate. 3. The leach rates. Source reduction methods seek to reduce the magnitude of any or all of these parameters. In general the dose rates are proportional to the source terms. For radon production the source term is proportional to the product of the radium concentration, R, and the emanating power, E, so that the risk is reduced by the same factor that reduces RE. For example, if the radium content is reduced by 95 percent, but E is increased by a factor of two, then the dose rates are reduced by an order of magnitude. The source term for the groundwater pathway is not as easy to identify. The peak in the radium concentrations in the accessable water body can also

Jan 1, 1981

By Pooyan Asadollahi, Praveen Krishna, Michael Joye

"Durability design for underground structures is an increasing focus of designers and owners in the underground construction industry. Many owners have expanded their requirements for durability design, with specific requirements for structure lifecycle and designer certification of structural durability. This paper describes current trends and best practices including: defining the underground structure lifecycle, historically durable underground structures, design methods for underground structure durability built of reinforced concrete, and durability of materials. Criteria to be used for defining end of structure life and owner’s maintenance responsibilities are crucial to lifecycle contract requirements. Current practices of several major owners are presented. Design methods are presented including United States code requirements. Current best practices for enhancing the durability of materials used in underground construction are discussed including: low permeability concrete, steel reinforcement concrete cover, the use of steel fiber, and testing for verification. INTRODUCTION Durability design is increasingly being recognized as an essential component of good design practice. Infrastructure owners recognize that to serve the public interest, constructed facilities must be lasting and durable. The public understands that structures with limited service life result in increased costs and add to their daily inconvenience with frequent repair and reconstruction. Engineers are increasingly asking not only is the structure strong enough but will it last for generations. Durability design requirements are no longer just adherence to some accepted practices, but are based on analytical approaches, with results that can challenge our beliefs in what construction materials and details result in a durable structure. This paper describes current industry requirements and practices for durability design of underground structures, and offers some suggestions regarding future trends and developments. SERVICE LIFE DEFINITION The service life of a structure is the sum of the time to onset of deterioration, called initiation period (ti), and the subsequent time period of deterioration ending when the structure is no longer functional, called propagation period (tp). Figure 1 shows a conceptual service life diagram. These time periods can be substantially affected by the level of maintenance performed during the life of the structure."

Jan 1, 2016

By Alexander Filimonov, Yury Bloshteyn

The development of a high-efficiency control system for mine ventilation is a complicated scientific and engineering problem. As a result of high-costs and difficult conditions involved in experiments for the development and investigation of mine ventilation systems, simulation is a critical task in cost reduction and productivity. The paper presents the description of a universal simulation model for controlled aerodynamic processes in an Underground ventilation Network (UVN). The high-efficiency programming tool to design and investigate mine ventilation control systems (MVCS) is also suggested.

Jan 1, 1991

By J. Mark Richardson

Steady-state flowsheet simulators for mineral processing plants have evolved to a current high level of utility and accuracy. Reliable, general-purpose, semi-empirical models now exist in nearly all unit operations categories particularly in the areas of comminution and classification. .These models, installed as user-selectable functions within the integrated frame- work of flowsheet balance-solver software systems, can be strung together to represent any plant configuration. In addition, CAD-like graphics, data reconciliation and model parameterization functions have become standard features of the current generation of integrated plant simulators. These advances have given engineers the capability to investigate many different plant scenarios while requiring a minimum of actual plant testwork. This paper describes a methodology and an integrated software package which are being successfully applied in a number of operating plants worldwide to predict plant performance under changing conditions. Those conditions which can be changed include effect-of ore type, feed size, water addition rates, equipment geometries and flowsheet modifications. By using data from actual plant optimization exercises in real mills, the paper illustrates and out- lines a technique which includes plant data collection, ore breakage testing, flowsheet simulation, model-fitting (parameterization), data adjustment and model experimentation. Brief descriptions of some unit operations models, such as autogenous mills and cyclones, are provided as examples of the current state of such models. Ore breakage testing and its relation to certain models is also discussed. Computer- generated size-distribution graphs, along with tabular data generated by the simulator, round out the presentation and serve to demonstrate the real- ism and accuracy of the models. The paper concludes with a partial list of cases where this technology has been successfully applied.

Jan 1, 1992

By J. Y. Kim, S. L. Chryssoulis

Lead ions that originate from galena during the processing of complex sulfide ores migrate onto the surfaces of sphalerite and iron sulfide minerals. This results in poor selectivity during differential flotation. Generally, in sulfide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. The surface lead complicates the zinc flotation circuit by lowering the concentrate grade. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zu and Pb-Zu ores is discussed. Plant and laboratory-test data are interpreted by determining the surface compositions of individual grains of sphalerite and iron sulfide particles. For the first time, surface compositions were determined by using laser-ionization mass spectrometry (LIMS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Cationic and cationic species on the surface were analyzed to elucidate the phenomena. It was proven that these new techniques are very useful in understanding the basic mechanisms of a sulfide mineral-flotation system.

Jan 1, 1997

By N. M. Cheimanoff

GEOCAD is an ambitious research program aimed at the development of a computer based system assisting the geologist and the production or planning engineer. BONANZA, its mining part, is a computer production scheduling tool (short to medium term) of particular relevance to complex orebodies. The principle is to simultaneously use a powerful information management system (CAD potentialities) and small expert modules integrating the exploitation context and the engineer's knowledge (Artificial Intelligence tecniques). As an illustration, a module of mineable block determination for underground exploitation is discussed.

Jan 1, 1989

By W. M. Kidd, P. J. Duport

INTRODUCTION The enquiry of the Royal Commission on Health and Safety of Workers in Mines of 1976, known as the Ham Commission after its chairman, Dr. J. Ham , now president of the University of Toronto, was one of the activities surrounding the upturn in the fortunes of the Canadian uranium industry and its markets in the mid-seventies. Although the regulation and licensing of Canada's ten major mine/mill facilities employing six thousand or more uranium mines is a federal concern under the Atomic Energy Control Act, this Commission, which paid particular attention to health and safety in uranium mines, was appointed by the Province of Ontario. Further provincial enquiries in British Columbia, Saskatchewan and Newfoundland have been aimed at quantifying, reducing or eliminating the environmental and health impact of uranium production. This work has created a mosaic of provincial regulation in what is essentially a field of federal jurisdiction. Various organizations of the federal government related to its regulatory function in the uranium industry are outlined in Figure 1 showing the matrices of regulatory, advisory and research activities associated with the exploitation of Canadian uranium resources. A more detailed examination [ ] of the governmental (federal and provincial) activities, commissions, etc., in the Canadian uranium industry indicates a definite parallelism of effort, if not of scale between the two levels of government in the execution of their roles in occupational and environmental health and safety and is presented here to explain the complex stage onto which the Canadian Institute for Radiation Safety has just entered. The development of the Institute and its precursors together with current and planned research activities are described. BACKGROUND Traditionally and constitutionally, natural resource exploitation and its regulation is under provincial jurisdiction; however, the uranium industry has been under federal control since the Second World War when security measures necessitated the creation of the Atomic Energy Control Board (AECB). Health and safety aspects, in terms of inspection, compliance and environmental monitoring are performed on behalf of the AECB by provincial labour inspectors (Saskatchewan and Ontario) and Ministries of Environment. Non-radiation health and safety matters are also enforced under the federal Canada Labour Code by provincial inspectors. In support of licensing and standard-setting functions, major research programs have been initiated and expanded at both the AECB and the Canada Centre for Mineral and Energy Technology (CANMET), formerly the Mines Branch of the Federal Department of Energy, Mines and Resources). CANMET established a Mining Research Laboratory at Elliot Lake, Ontario in 1965 to conduct research and development aimed at improving production capability, providing information on the security of uranium supply and investigating the hazards of mining and their implications for the health and safety of the miners. The provincial route in assessing the costs and benefits of uranium production has attempted to be far more conclusive in nature. While some on-going studies are funded, periodic inquiries by Royal Commission have become the accepted practice. Six such inquiries have been conducted in four provinces and widely differing policies have resulted from their findings and recommendations. For example, while the government of British Columbia in the Fall of 1980 declared a seven-year moratorium on(2) uranium mining and exploration in the province, the province of Ontario's crown utility "Ontario Hydro" financed the rehabilitation of a mine/mill complex at Elliot Lake. The latter instance is not surprising considering that the final report of Ontario's "Royal Commission on Electric Power Planning",(3) concluded that nuclear energy has a continuing role to play in the expansion of Ontario Hydro.

Jan 1, 1981

By F. L. Wilke

Bong Mining Co. Ltd. in Liberia, West Africa, operates an iron ore open pit some 60 miles northeast of Monrovia. The production is at present about 40,000 t/d (metric tons/day) from which about 18,500 t/d concentrate with 65.5% Fe is produced. The ore waste ratio is about 1: 1.5 to 1:2. The technical layout and the equipment are very similar to those in many modern open-pit operations as described by Jacobs and Thomson (1967). As described by Lersch in detail (1966), the deposit is a very irregular one. The quality of the ore changes within very short distances with regard to both physical conditions (hardness) and chemical properties. Very soft and very hard ore as well as high-grade and low-grade ore are found adjacent to each other. In addition, there are enclosures of sterile rocks. For the purpose of identification and production scheduling, 12 different types of ore are distinguished.

Jan 1, 1979