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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 J. J. K. Daemen, C. Fairhurst

Two aspects of tunnel support design are considered, and for both particular attention is paid to the influence of rock failure around the tunnel on the loads developed on the supports. 1) In general it has not been possible to extend analytical methods for the study of rock failure around tunnels to three dimensions. As a consequence it was not possible to calculate either the influence of the face or the actual sequence of support loading as the face advanced. The finite element method made this extension possible. A simplified analysis of the influence of the face and of the sequence of support installation has been made. The influence of the original stress field and of the rock behaviour on the length of tunnel which can be left unsupported (related to the stand-up time) is shown. The degree to which a 2-dimensional analysis can be used to approximate the final support load is shown to be dependent upon the post-failure behaviour of the rock. 2) Tunnel support design requires a knowledge of the forces and of the -rock displacements which cause stressing and deformation of the support system. A 2-dimensional model incorporating a detailed representation of several support systems, of the rock behaviour in the broken zone and of the interaction between rock and support is given. The model allows the calculation of the stress distribution in the support. The significance of the relative stiffness of support and rock on the stresses developed in the support is shown.

Jan 1, 1997

By Gregory R. Wagner

As you know, NIOSH is the part of the United States Public Health Service with responsibility for conducting and supporting research leading to prevention and control of occupational diseases and injuries. Some years ago, NIOSH went through a process of identifying and leading occupational health and safety problems in the United States. Candidate problems were evaluated in terms of the number of people affected, the importance of the effects, and how amenable the conditions are to preventive interventions. Lung diseases were ranked first on the resulting list. Diseases from mining continue to contribute substantially to this unfortunate position of prominence. The work of the Generic Center is one of many answers to this critical problem. Although the research is often expressed in terms of dust characterization or dust control, the reality is that high dust levels are much like high blood pressure. No one cares about hypertension per se. We are concerned about the consequences of exposure to untreated high blood pressure--heart disease, kidney disease, and stroke. Similarly, if dusts were truly only a nuisance, there would be little justification for the diverse research program supported by the Bureau of Mines or by NIOSH. But mineral dusts do cause a range of significant health problems: pneumoconiosis, bronchitis, and emphysema. The research supported by the Center is aimed at doing something about them. Within a public health approach to occupational health, we have a hierarchy of interventions. Primary prevention of problems is prevention at the source: solving a problem before it affects a worker. What we call secondary prevention is an attempt to identify health problems at a sufficiently early stage that some intervention will interrupt the disease process or the development of significant impairment. Tertiary prevention refers to rehabilitation of the worker who has already suffered significant loss of function. At NIOSH, and in the Generic Center research programs, the focus is on primary prevention. Basic investigations into those things about specific dusts that promote or reduce toxicity is critical for our understanding of how to prevent disease. Also, the search for engineering solutions to reduce or control dust generation is essential to solving problems of dust over-exposure. But until the engineers create the foolproof safe environment, it will also be necessary to discover better ways to identify the earliest markers of disease. To do this, we must explore and explicate the basic mechanisms of disease through laboratory investigations as well as human observation and physiologic testing. The unique opportunity provided by the Generic Center program and highlighted in this diverse program over the next few days is that these efforts are being carried out in multiple disciplines concurrently. Also, there are periodic small and large gatherings such as this one where investigators have the chance to get together, formally present papers, and informally stimulate each other's progress towards disease prevention. To ignore the potential for this cross-cutting interaction would be a significant loss. To take full advantage of it is potentially revolutionary. I recently pulled out a book I hadn't read since I was an undergraduate. It specifically concerns the nature of intellectual ferment surrounding the development of the concept of a sun-centered rather than an earth-centered universe in the sixteenth century. The book is about more than developments in astronomy: it is a discussion of the nature of scientific revolutions. Scientific revolutions result from the brilliance, insight, and good fortune of the few superimposed on the evolutionary work of the many. They both cause and reflect significant itellectural and social ferment. For example, the revolutionary work of Copernicus in recognizing the limitations of the concept of an earth-centered universe reflected contemporaneous developments in optics, mathematics, physics, economics, and philosophy.

Jan 1, 1991

By Robert Cooke

This paper shows how technology developed to analyse stabilised slurries can be applied to paste flows. The rheological characterisation of paste mixtures using the generalised yield pseudoplastic rheological model is described. It is noted that the slump test does not provide a complete rheological characterisation of a paste. Methods for calculating pipeline pressure gradients for laminar and turbulent flow are presented. The minimum pressure gradient is an important consideration to ensure that solids do not settle on the pipe invert. Important points to be considered for a pipe loop test programme are noted. The usefulness of the pseudo shear diagram for scaling pipe loop test measurements is demonstrated. Issues to be considered for the design of paste reticulation systems are discussed.

Jan 1, 2001

By J. C. Danza Errico

The bauxite deposits on the Pocos de Caldas Plateau in the state of Minas Gerais, Brazil, were formed by the differential weathering and leaching of alcaline rocks in a ring structure. Their action on steep topography formed heterogeneous ore posture and chemical grades. Variographic analysis of several of these deposits show nested structures that are probably related to ore genesis. Kriged ore reserves estimation are presented with emphasis on the data pro cessing method that was employed. Programs were written in APL. Its intrinsic use of matrices contributed to faster programming and less computer time. In many cases looping was eliminated. The high resolution graphic resourses of APL. workspace facilitated programming of variogram analysis, fitting, and regularization. APL sub-routines are presented for variogram calculation and kriging.

Jan 1, 1986

By Ken J. Fair, Vicken H. Aprahamian, Gus Van Weert

A consortium of Canadian mining companies, engineering firms and the Ontario Government has supported Hydrochem's efforts in the last year to design and cost a 10 tpd NITROX PROCESS® demonstration plant. A 5 kg per hour mini plant was installed at the Hydrochem facilities in Brampton, Ontario. This paper describes design testwork on Dickenson Mines arsenopyrite concentrate and application of the findings to the demonstration plant flowsheet. The control of nitrates in discard solids and stack gases is discussed in detail. Nitric acid oxidation of arsenopyrite results in significant ele- mental sulphur formation, enough for it to be detrimental to sub- sequent cyanidation. Flowsheet variations aimed at dealing with this process characteristic are discussed and testwork results on one option (hot liming) are described.

Jan 1, 1988

By Waclaw Trutwin

The idea of automatic or remote control of the mine ventilation process generally, and methane concentration particularly, attracts the attention of mining engineers more and more. The advantages of introducing mine ventilation control systems are breaking traditional reluctance. The change of attitude is not only because of the requirements of modern exploitation technology, but it is also due to the recent progress in development and successful introduction of reliable monitoring systems and actuators in the form of controlled ventilators and doors [1]; [2], [3], [4], [5], [6]. Many 'years of theoretical and experimental studies of the dynamics of mine ventilation processes created the needed base for a proper design of an automatic control system [7],[8],[9], [10]. From these studies must, however, be drawn a fundamental conclusion, which may be regarded as the motto of this paper: An automatic control system for mine ventilation ill-conditioned or improperly designed is capable of creating hazard situations in response to random disturbances, much more, severe in consequence than a traditional ventilation system without any automatic or remote control! This statement is easy to prove if the dynamic properties of the ventilation process are taken into consideration. The ventilation process, as a matter of fact, is described by non-linear equations, and it must be expected that the process has more than one state of equilibrium. In other words, in the ventilation process may exist not only one but also more than one steady-states of flow, of which some are stable and others unstable. In certain circumstances, there may be no steady-state at all, and the process will oscillate [8], [11] , [12] . The state of flow in a network tends towards a steady-state and the actual steady-state established will depend on the initial conditions or disturbances in flow (fire,. etc.), which steady-state from the total number that will be . We frequently observe jumps from one steady-state to another. Disturbances in flow conditions which may cause such transitions are events of random character, occurring very rarely. Concluding, it must be stressed that there has to be a control system adjusted to the ventilation process in order to avoid situations mentioned above. There is only one alternative available and suitable for examination or study of the dynamics of a given mine ventilation problem: either by continuous monitoring of the real process, or numerical simulation of the process using a mathematical model. The advantages of the second method are obvious. This method allows consideration of every possible case very quickly and cheaply in relation to the first method. The aim of the paper is to show again that the simulation of the mine ventilation process and particularly a methane concentration process, separately or combined together with a control system, are real possibilities. A simulation method requires precise specification of the problem under consideration. For example, if we intend to examine a methane-concentration control system, the following items have to be specified: - expected target function of the control system. - structure of the control system. - mathematical model of control system, including sensor system, data preparation system, controllers, decision routine, regulators, etc. - structure of mine ventilation network. - mathematical model of ventilation process, including air flow and methane concentration processes. - pattern of disturbances which may occur in the controlled process as well as initial conditions on a 'start-up' of the system. Using typical computer programs for numerical solution of equations in the mathematical model of the problem involved, we are able, within the adequacy of the model, to simulate every case specified by the disturbances and initial conditions. As a result of simulation, it is expected that the following parameters could be defined: - transient flow in the network. - transient state of methane concentration in working areas. - stability of flow and methane concent¬ration. - stability of the control system. - range of control. - efficiency of control, etc. It is obvious that simulation methods readily allow for modifications to existing systems such that desired results will be obtained. Also optimisation problems could be solved by use of the simulation methods. In order to illustrate these general thoughts, a brief presentation of a mathematical model of methane concentration and

Jan 1, 1980

By Michael C. Newbury

For thousands of years gold has been not only a commodity, valued for its comparative scarceness, immutability and homogeneity but also a medium of exchange which has no nationality. Approximately 90% of the gold produced is still accessible in the world, although some of it in museums, galleries, jewellery and dental work is not immediately available for circulation. The majority is held as bars by central banks for their reserves; the balance circulates as coinage or bullion held for investment. The value is further enhanced by the political aspect that gold cannot be debased as paper currency can and, therefore, it always becomes an investment refuge. It has always been possible to buy and sell gold at a price which is readily established by reference to bullion's weight and purity; and it is this fact which makes a loan denominated in gold, rather than one in currency, a viable alternative means of finance. The purpose of this paper is to discuss some general aspects of what is considered to be one of the more effective and presently popular methods of financing the development of a gold mine - the gold loan. This is not intended to discuss all the minute details which must be uniquely designed to fit each individual situation, but rather to provide general guidelines. You will all be aware of the traditional sequence whereby companies primarily finance exploration work by the raising of equity through the sale of shares to the public or by that unique Canadian form.

Jan 1, 1987

By Terry P. McNulty

During the last 30 years, at least ten authors have dealt with startup ("ramp-up') times for minerals beneficiation, hydrometallurgical, and/or pyrometallurgical plants. Most have attempted to identity the reasons for delays and some have suggested attributes common to successful startups, as well as those shared by unsuccessful ones. The most recent has advanced a project characterization matrix as a predictive tool for qualified users. This paper will summarize past work, will review cause and effect, will outline an approach for refining our ability to avoid costly delays, and will seek guidance from professionals most likely to use such a tool. INTRODUCTION During the last few decades, many billions of dollars have been lost by investors in mineral industry projects that did not perform as well as their developers had hoped. The most common form of failure has been the inability to generate a profit quickly, and delayed achievement of planned production rate has been the chief cause. Minerals processing projects are by no means the only kind of plant to suffer from startup delays, as some authors cited in this paper considered inorganic chemical plants and other types of facilities. Furthermore, mines are not without fault and there have been many that were closed after years of disappointing performance. However, our interests as a group are most sharply focused on mineral processing and our database for such projects is relatively extensive. It is sufficient to say that the conclusions made or repeated in the following text can be readily extended to most types of projects.

Jan 1, 2004

By Ralph J. Holmes

INTRODUCTION Although sampling techniques used by the mineral industry continue to improve, sampling is still an area which is often neglected. Frequently, sampling and sample preparation requirements are left to personnel who do not fully appreciate the significance and importance of sampling. Consequently, plant evaluations are often based on seriously biased samples, leading to mass balance problems and incorrect assessments of plant performance. The basic rule for correct sampling is that each particle of ore or concentrate must have an equal probability of being collected and becoming part of the final sample for analysis. If this is not the case, bias is easily introduced and the sample is not representative. For example, when ore is travelling on a conveyor belt, the lumps may come to the surface. Consequently, a grab sample taken from the top layers only will contain a greater proportion of lumps, i.e., the sample is biased. There seems little point in making major investments in precise analytical equipment, if the sample provided to the analytical laboratory is not representative in the first place. This paper describes the sources of plant sampling errors, reviews the methods of estimating their variance, presents some worked examples, and provides some practical advice for reducing sampling errors and their variance. SAMPLING BASICS It is generally accepted that the discharge point of an ore or concentrate stream is the most suitable sampling location. The stream can be intersected at regular intervals, and representative samples, referred to as increments, can be obtained by taking a complete cross-section of the ore stream. On the other hand, sampling devices that take part of the stream on an intermittent or continuous basis, e.g., a bleed from a pipe, may introduce serious bias, and should be avoided at all cost. Increments may be taken at completely random times or tonnages during the sampling operation, in which case it is called "random sampling". However, as shown below, random sampling results in the largest sampling variance, so it is preferable to divide the ore or concentrate stream up into strata of equal time or mass and take one increment from each stratum. This operation is called stratified sampling and may be either systematic sampling, in which increments are taken at the same point in each stratum, or stratified random sampling in which the increments are taken at random within each stratum. Systematic sampling results in the smallest sampling variance, provided periodic variations in quality or quantity are not present which may coincide with, or approximate to, any multiples of the proposed sampling interval. In such cases, it is strongly recommended that stratified random sampling within fixed time or mass intervals be carried out.

Jan 1, 1991

By E. De Souza, H. Heidrich

In underground operations the evaluation of blasting fume dilution times and the application of recirculation techniques require accurate determination of the concentration of toxic fumes produced by the explosive used. This paper describes a methodology for obtaining concentrations of detonation products from commercial explosives tested under typical rock confinement and looks into the development of techniques for reducing toxic gases produced by explosives. This paper also analyses the application of techniques for the removal of toxic gas which would enable reduced re-entry times, a reduction in the quantity of fresh air and the use of air recirculation techniques, thereby providing substantial economic benefits to the industry. INTRODUCTION Toxic fumes from blasting operations are among the most common and serious hazards encountered underground. The implication of high concentrations of toxic gases emitted from blasting on the mine ventilation system are very significant and, in many cases, catastrophic results have occurred. Because blasting is a routine practice underground, the mining engineer is always confronted with the problem of controlling the fumes within acceptable levels. Typical control procedures employed underground include preventing or reducing the amount of fumes liberated from blasting through the proper selection of explosives and proper blasting techniques; removing the fumes through local exhaust systems or auxiliary ventilation (dilution ventilation); blasting off-shift, or at restricted times; localizing or isolating the effects of blasting where workings are isolated or sectionalized in the ventilation system; and absorbing some of the components of the fumes using air-water sprays. Dilution is one of the most effective control measures against blasting fumes and is universally applied. However, for precise determination of the dilution times for the fumes to reach safe concentrations, accurate determination of the concentration of toxic fumes produced by the explosives used is required. Research work has been carried out in determining the types and volumes of gases produced from blasting. In the case of ideal detonations, the nature and quantity of the fumes produced can be predicted by thermo-hydrodynamic calculations. However, commercial explosives exhibit non-ideal behaviour which is enhanced by the relatively small diameters of application in underground mines. The confinement offered by the surrounding rock further complicates the situation. It is well recognized that confinement affects performance and consequently fume generation. A detailed data base of fumes generated by commercial explosives at various conditions is introduced and the effect of blasting parameters such as, confinement, shock desensitization and incomplete detonations on toxic fume production is described for a variety of commercial explosives in use today. Thermodynamic predictions on fume production by the explosive compositions tested are also presented and compared with experimental results and their significance in assessing the quantity of fumes produced is discussed. A mathematical model capable of determining dilution ventilation requirements and dilution times to reduce the fume concentrations in the blasting zone to acceptable levels has been developed and it is being incorporated into a network system so that the effects of blasting can be simulated in typical mine ventilation systems. Solutions to the problem of controlling blast fumes within acceptable levels are described. These solutions include the use of control procedures which prevent and reduce the amount of fumes liberated from blasting. The use of low fume explosives, proper blasting techniques, dilution ventilation and filtration can be combined to effectively control fume production and save on costs. The application of these techniques to enable recirculation of underground air with reduced quantities of fresh air requirements is evaluated in a case study.

Jan 1, 1993

By Bruce Kennedy, William Hustrulid

Georgius Agricola in 1556 wrote De Re Metallica, one of the first and probably the most famous of mining reference works. In Book 1 he reflects rather elegantly on mining and miners. "Many persons hold the opinion that the metal industries are fortuitous and that the occupation is one of sordid toil, and altogether a kind of business requiring not so much skill as labour. But as for myself, when I reflect carefully upon its special points one by one, it appears to be far otherwise. For a miner must have the greatest skill in his work, that he may know first of all what mountain or hill, what valley or plain, can be prospected most profitably, or what he should leave alone; moreover, he must understand the veins, stringers, and seams in the rocks. Then he must be thoroughly familiar with the many and varied species of earths, juices, gems, stones, marbles, rocks, metals, and compounds. He must also have a complete knowledge of the method of making all underground works. Lastly, there are the various systems of assaying substances and of preparing them for smelting; and here again there are many altogether diverse methods. ... "Furthermore, there are many arts and sciences of which a miner should not be ignorant. First there is Philosophy, that he may discern the origin, cause, and nature of subterranean things; for then he will be able to dig out the veins easily and advantageously, and to obtain more abundant results from his mining. Secondly, there is Medicine, that he may be able to look after his diggers and other workmen, that they do not meet with those diseases to which they are more liable than work- men in other occupations, or if they do meet with them, that he himself may be able to heal them or may see that the doctors do so. Thirdly follows Astronomy, that he may know the divisions of the heavens and from them judge the direction of the veins. Fourthly, there is the science of Surveying that he may be able to estimate how deep a shaft should be sunk to reach the tunnel which is being driven to it, and to determine the limits and boundaries in these workings, especially in depth. Fifthly, his knowledge of Arithmetical Science should be such that he may calculate the cost to be incurred in the machinery and the working of the mine. Sixthly, his learning must comprise Architecture, that he himself may construct the various machines and timber work required underground, or that he may be able to explain the method of the construction to others. Next, he must have knowledge of Drawing, that he can draw plans of

Jan 1, 1982

By Kegomoditswe Koitsiwe, Tsuyoshi Adachi

"This paper characterizes quarterly LME copper price fundamentals from 1995 to 2011 by analyzing the transformation of the market mechanism based on structural change perspective. Using chow test for structural change based on the least square multiple regression, we divide the price fluctuation into: Stable price period (1995Q3-1999Q2), Low stable price period (1999Q3 – 2003Q3) and Price fluctuation period (2003Q4 – 2011Q2). The results show the existence of structural breaks disproves the investigation of the full sample period as a whole. In different structural breakpoints the main drivers of copper prices changes and their impact are significantly different. Moreover, the paper examines the role of speculation in copper price fluctuations.Introduction The rise in commodities price volatility and financial and economic crisis have led to questions over the organisation of futures and physical commodities markets. Spikes in commodity prices and volatility have coincided with a surge in financial speculators in the commodity markets inspiring a polarised and hotly debate among academics and practitioners about the role of investors in the development of physical markets. In his seminal work Kaldor (1939) focused primarily on whether speculative activity in the futures markets reduces the variance of commodity spot prices. Yet, part of the literature finds that the introduction of futures contracts destabilizes the spot market. IMF (2006) studied commodities boom and its causes concluding that there is little support for the hypothesis that speculative activity affects either price levels over the long run or price swings in the short-run. The impact of speculative activity on commodity prices remains a highly contentious topic. Other market analysts take the view that the supply and demand for physical commodities remain the major determinants of market trends (Krugman 2008). It is the aim of this study to contribute to the literature by examining the drivers of copper price changes from a structural change perspective. In this context we are attempting to answer to: What are the main drivers leading to copper price fluctuations? Are these factors having the same effect in different periods or not? It is meaningful to understand drivers of copper prices and thereby, their fluctuations because it will help developing countries depending on copper export to anticipate market situation and avoid bad economic development challenges that can result from price fluctuations. Moreover, this can ensure sustainable mineral supply."

Jan 1, 2017

Horizontal stress is an important factor that contributes to roof failure during a long wall entry development, especially when the immediate roof is weak. In this study, the effects of the three factors, the stress angle between the maximum horizontal stress and entry development, the stress ratio of the maximum to the minimum horizontal stresses, and the sequence of entry development, on the stress distributions in the weak immediate roof of a three-entry system are analyzed using the finite element method, when the horizontal stress is fixed. The results have confirmed that the stress angle has a significant influence on the stress distributions. Generally, the three-entry system is in the worst stress condition when the angle is about 60°_75°. The stress ratio has little effect on the roof stresses. In addition, the sequence of entry development has also little effect on the roof stress for the specific case analyzed.

Jan 1, 1999

By Fathi Habashi

THE CHOICE of a precipitant for a certain metal ion depends, beside the economic factor. on the following factors: 1) The precipitant should be specific as far as possible so that pure precipitates can be obtained

Jan 1, 1970

By N. R. Joshi, A. D. Agate

It is estimated that more than 80% of phosphate rock output in the world is used for fertilizer production. In India, there are only a few high-grade deposits of phosphate ores; therefore, most of the requirement for phosphatic fertilizers is satisfied with imported DAP (diamino phosphoric acid). Due to the drain on foreign exchange reserves, this import-dependent, essential commodity is in short supply in India and, therefore, is sparingly used by farmers. In addition, of the added phosphorus, normally 80% becomes unavailable to plants because phosphorus complexes are formed in soil, causing deleterious effects on plants. In our laboratory, this problem was tackled by using a bacterial consortium of phosphorus-solubilizing bacteria. It resulted in the speeding up of seed germination and increasing available phosphorus in the soil by 14%, over a period of 80 days. To use the low-grade deposits of phosphatic rocks available in India near Hirapur, Madhya Pradesh, India, which contain high amounts of iron, beneficiation through microbial means was used for phosphorus removal. Beneficiation was achieved partially through removal of extra iron by oxidizing ferrous iron from the ore by a Thiobacillus species after removal of impurities containing both silica and iron, instead of sieving and cleaning the ore using different techniques. This resulted in a cleaner ore, with nearly 70% of such impurities removed. The factors for beneficiation technique were standardized at the laboratory level and are being used for scaling up of the process. Thus, the beneficiation of phosphatic rock from Hirapur will be an important first step of phosphorus production in India.

Jan 1, 1999

By R. V. Ramani, K. V. K. Prasad

Forecasting mined grade variability from exploration information is a challenging task in mine planning. For effective planning of activities, such as workplace scheduling, ore grade quality control, etc., development of realistic numerical simulation models of in situ variability from exploration information is an essential first step. Geostatistical conditional simulation (GCS) is one of the well known methods to develop such simulations. Recently, stochastic fractal models based on the assumptions of scale-invariance and self-similarity have been used for developing simulations of several natural phenomena. It has been suggested that these models might permit the generation of short-scale variability information from exploration data with greater fidelity when the data satisfies the attendant assumptions. In this paper, stochastic fractal models are reviewed, and their relationship to geostatistical variogram models is examined. A comparison of the two simulation techniques has been performed using coal sulfur data from a mined-out coal property. The results of this comparative analysis are also presented in the paper.

Jan 1, 1993

By John P. Smith

As the US looks within its borders in its drive toward energy independence, economical coal transportation, particularly from vast western reserves, becomes an increasingly difficult but compelling challenge for both the country and the coal industry. Coal producers continue to develop improved technology for more efficient and cost-effective coal mining and processing. But for controlling transportation costs, coal producers must rely on a delicate balance between product demand, competition among carriers, federal regulation, and a symbiotic relationship with coal transporters. In 1981, 739 Mt (815 million st) of coal were mined in the US. Nearly 90% of this coal was moved via

Jan 10, 1982

By Chris C. Sundberg, Ronald E. Heuer, Stanley L. Paul, Peter M. Douglass

Use of prestressed concrete cylinder pipe (PCCP) for pressure tunnel liners is gaining popularity with contractors, engineers, and owners. This paper presents loading considerations and a beam-spring computer model approach to tunnel liner analysis, together with ultimate strength (US) and service load (SL) procedures for liner design. The US procedure is best suited to check for adequate liner strength under extreme loading conditions. The SL procedure, based on conventional pipeline design practice, is considered more appropriate when addressing crack control and serviceability under normal working load conditions. Other design and construction considerations are discussed and a design example is presented.

Jan 1, 1987

By Helen Leung, Colin R. Phillips

The performance of personal alpha dosimeters in mixed radon daughter and thoron daughter atmospheres in Ontario uranium mines is described together with monitoring developments which enable the radon daughter working level to be determined separately. The theoretical bases for continuous and integrated working level measurements based on individual and gross counts are presented in terms of the weighting factor for combining the thoron daughter working level with the radon daughter working level, and in terms of the in-growth time of the air. Implications for the determination of working level in the presence of thoron daughters are discussed.

Jan 1, 1981