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By J Levett, O Rondon, I Glacken

Reporting Codes are not prescriptive on methodologies to report or classify Mineral Resource Estimation results, but the assessment of risk and uncertainty is required, and is likely to be increasingly important in future Code updates. The 2012 JORC Code indicates that relative confidence in tonnage-grade estimations should be considered for classification, and that there should be a discussion of relative accuracy and confidence levels in the Mineral Resource Estimate. These considerations are also relevant to the drill hole spacing required for various classification categories, along with other geological and data quality criteria. This paper summarises the theory, principles and current practice of various drill hole spacing analysis techniques for both achieving a desired level of resource categorisation and for optimising grade control or resource drill-out costs. The authors provide practitioners with a guide in their use to assess uncertainty and relative accuracy, as illustrated by a number of case studies. While all drill hole spacing studies rely on the assumption of consistency of the continuity model from current to future drilling, the range of methods available provide much more objective outcomes than previously adopted ‘rules-of-thumb’.

May 24, 2023

By W. Jacobi

INTRODUCTION The radon problem concerns the radiation exposure from inhaled short-lived radon daughters and the associated risk for the induction or promotion of lung cancer. In several groups of miners which were exposed in the past to relative high radon levels during their underground work, an excess lung cancer frequency has been observed. On the basis of these findings it has to be stated that the inhalation of radon daughters is the most important radiation hazard in mining. Involved in this radon problem in mines are the difficulties to measure the individual radon daughter exposure of miners and to estimate the dose to critical cells and target tissues in the lung from inhaled radon daughters. And finally the reduction of radon levels in mines confronts us with special technical problems which are difficult to solve. Thus the setting of annual limits for the radon daughter exposure of miners alone is not sufficient to guarantee an appropriate standard of radiation safety. Of same importance are the improvement of air monitoring and the optimization of technical protection measures in mines. This has to be kept in mind for the following considerations on exposure limits. The ICRP has recommended in 1959 for the first time a maximum permissible concentration (MPC) for the occupational exposure to radon and its short-lived daughters (ICRP, 1959). This MPC in air was derived from a maximum permissible dose equivalent of 0.15 Sv (15 rem) per year to the epithelium of the large bronchi which was regarded as the "critical tissue". This old MPC-value was derived using a simplified lung model which paid main attention to the dose contribution from the inhalation of unattached 218Po(RaA) atoms. Since this time more realistic dosimetric models for radon daughters have been developed; some of these models will be presented in special papers on this conference. Furthermore in the last 10 - 20 years substantial epidemiological information on the lung cancer risk among several groups of Rn-exposed miners has become available. Taking into account these epidemiological and new dosimetric findings the ICRP has adopted in March this year new recommendations on occupational limits for inhalation of 222Rn, 22ORn and theirshort-lived daughters. This report will be published this year as ICRP Publication 32 (ICRP 1981). The recommended limits for radon daughters were derived from the basic dose and risk limits as they were proposed by ICRP in its new basic recommendations (ICRP Publ. 26, 1977). In the following this basic system of dose limitation is shortly outlined before the special recommendations for radon daughters are described. [BASIC CONCEPTS AND LIMITS] The new basic recommendation of ICRP (Publ. 26, 1977) proceed from the assumption that in the dose range which is relevant for radiation protection, the risk RT of so-called stochastic radiation effects (carcinogenic and genetic effects) in a target tissue T increases proportionally with the mean dose equivalent HT in this tissue: RT = aT HT. If several target tissues are irradiated the total individual (stochastic) risk is given by the sum of risks in these tissues: [R = ?TRT = ? T aT HT]. Thus this concept of individual health detriment takes into account the risk contribution from each relevant tissue. It replaces the old concept of the critical tissue, which neglected the exposure of other tissues. Applying this new concept a dose quantity can be defined which is proportional to the total individual radiation risk from stochastic effects. This so-called "effective dose equivalent (HE)" is given by the sum of the weighted dose equivalents in the relevant tissues: [HE = E wT HT with E wT = 1 T '1] The weighting factor wT of each tissues follows to wT = aT/awB, where awB is the total stochastic risk coefficient for a uniform irradiation of the whole body. For the lung as a single organ comprising several target tissues, the ICRP recommends a total weighting factor w = 0.12 (ICRP 1977/79). This concept of risk or detriment, respectively, has important consequences. To meet the objectives of radiation protection the new ICRP-system of dose limitation is based on the following three principles: 1) The justification of practices involving radiation exposures; no pratice shall be adopted unless it produces a net benefit. 2) The ALARA-principle that all exposures shall be kept as low as reasonably achievable; this requires the optimization of the level of protection. 3) The limitation of individual exposure (annual dose limits). It is important to note that the dose limits for individuals are only one part of this system of dose limitation. Furthermore, these limits cannot be regarded as a boundary between safe and unsafe. They have to be interpreted as the lower boundary of an unacceptable exposure region. This means that in addition to the observance of these basic dose limits it is demanded to optimize the level of protection. Consequently the optimized exposure levels or the corresponding operational limits will be normally lower than

Jan 1, 1981

By Brent A. Slaker, Khaled M. Mohamed

"Understanding coal mine rib behavior is important for inferring pillar loading conditions as well as ensuring the safety of miners who are regularly exposed to ribs. Due to the variability in the geometry of underground openings and ground behavior, point measurements often fail to capture the true movement of mine workings. Photogrammetry is a potentially fast, cheap, and precise supplemental measurement tool in comparison to extensometers, tape measures, or laser range meters, but its application in underground coal has been limited. The practical use of photogrammetry was tested at the Safety Research Coal Mine, National Institute for Occupational Safety and Health (NIOSH). A commercially available, Digital Single-Lens Reflex (DSLR) camera was used to perform the photogrammetric surveys for the experiment. Several experiments were performed using different lighting conditions, distances to subject, camera settings, and photograph overlaps, with results summarized as follows: The lighting method was found to be insignificant if the scene was appropriately illuminated. It was found that the distance to the subject has a minimal impact on result accuracy, and that camera settings have a significant impact on the photogrammetric quality of images. An increasing photograph resolution was preferable when measuring plane orientations; otherwise a high point cloud density would likely be excessive. Focal Ratio (F-stop) changes affect the depth of field and image quality in situations where multiple angles are necessary to survey cleat orientations. Photograph overlap is very important to proper three-dimensional reconstruction, and at least 60% overlap between photograph pairs is ideal to avoid unnecessary post-processing. The suggestions and guidelines proposed are designed to increase the quality of photogrammetry inputs and outputs as well as minimize processing time, and serve as a starting point for an underground coal photogrammetry study.INTRODUCTIONThe stability of underground mine ribs has been a safety concern for underground coal mines for decades. Unfortunately, the average rib fatality rate has been about 1.3 per year between 1996 and 2013 (Jones et al., 2014). In an effort to better understand coal rib behavior, photogrammetry is being investigated in this study as a measurement tool for surveying ribs in an underground coal mine environment."

Jan 1, 2016

By E. Morrice

High-purity neodymium, praseodymium, and didymium (a cerium-free mixture of light rare-earth elements) were prepared by electrolysis of the oxides in a medium consisting of the respective rare-earth fluorides and lithium fluoride. The metals were electrodeposited in the liquid state and collected as nodules on a skull of frozen electrolyte. Cells were operated from 1,000° to 1,100° C. The requisite temperature was maintained by passing alternating and direct currents through the bath. Graphite was used for the anodes and tungsten for the cathode. The metal products contained <0.02 percent each carbon and oxygen and <0.025 percent tungsten as major impurities. Analysis of typical didymium metal nodules showed an approximately twofold enrichment in neodymium and praseodymium over their respective concentrations in the cell feed. The lanthanum content of the metal was about one-half its content in the oxide.

Jan 1, 1967

By Richard F. Hewlett

An attempt has been made to fit assay data from an underground copper deposit to a three-dimensional polynomial surface as a means of expressing assay points in terms of their mine coordinates by a mathematical equation. The resulting equation was evaluated to predict the grade trend of the deposit. Although the fit obtained by this initial experiment is not considered accurate enough to provide good predictions about the deposit, the methodology is presented in this preliminary report to show the potential usefulness of the technique in mineral deposit evaluation. The technique also should be useful in determining the grade of blocks of ore for production scheduling and blending problems in open pit operations. Further experimentation is needed to increase the reliability of the computer program, to increase the precision of the method, and to make the solution more flexible for use on other mineral deposits.

Jan 1, 1964

By G Chen

Magnesite and dolomite are two salt-type minerals. The surface characteristics of these two minerals are almost the same. It is very difficult to remove dolomite from magnesite ores by flotation process. The present study was performed to develop a new collector and a better flotation scheme for magnesite from dolomite. The flotation tests show that there exists a significant difference in flotability between magnesite and dolomite when dodecyl phosphate synthesised with dodecanol, phosphorus oxychloride and other chemicals is used as collector. Sodium silicate was used as the modifier to improve flotation selectivity. It was found that sodium silicate selectively depressed magnesite at pH 4.5 - 7.5. The separation of magnesite from dolomite was achieved in a reverse flotation which resulted in a 76.1 per cent yield of magnesite with a grade of 47.3 per cent at 100 ppm dodecyl phosphate and 75 ppm sodium silicate. The flotation mechanism was investigated by characterising surface electrical properties and measuring the adsorption density of the reagents on magnesite and dolomite.

Jan 1, 2005

By CHARLES M. SCHWAB

THE ENGINEERS have placed this great country of ours in a preeminent position with everything pertaining to manufacture, metallurgy, and the kindred arts. We are second to none in the world. We have a country which, another speaker has said, God has endowed with such riches in coal and natural resources as no other country in the world. But rich as these are, there is one thing greater; the sturdy character, energy, and integrity of its people, which will make these great resources an influence in the world&apos;s developments. Great as are these resources and the energy and integrity of our people, there is one problem of our .engineering, which I term human engineering, that is of far more importance than the creation of machines and methods, with which you have been so successful in the past. Of what value is the skillfully devised machinery, the complex process, unless manned and operated by people whose heart and soul are in sympathy with the work they are doing and who have before them the giving of a complete day&apos;s work for a day&apos;s pay?

Jan 1, 1920

By Samuel Hoyt

THE hardness of annealed copper has been given in the literature and is easily obtained by any of the standard methods of hardness testing. It is not our intention to correct published values or to add to them, but to describe tests of two bars of annealed electrolytic copper in which the methods of Meyer&apos;s analysis were employed. MEYER&apos;S ANALYSIS OF BALL INDENTATION TEST The ball indentation test is probably the most valuable hardness test we now have but, as it is carried out in the Brinell or Rockwell test, the result may be seriously in error without the operator suspecting such to be the case. This condition results from the isolated and uncontrolled nature of the measurement. The accuracy depends on the accuracy of the equipment and the care and skill used in the operations; there is nothing in the impression diameter, which is all that is measured, to indicate the presence of error. Meyer&apos;s analysis supplies a control of the measurements that goes far toward eliminating unsuspected errors. The principles of this work maybe obtained from elsewhere.1 As this subject has not received the attention of this Institute, it may be well to summarize the more important points as follows.

Jan 2, 1926

By Gabriel Riveros, Ariel Balocchi, Andrzej Warczok, Daniel Smith

Blister copper from converting of copper matte is processed by fire refining prior to electrorefining. The fire refining consists of two steps: copper oxidation with impurities slagging and copper reduction. The classical batch process is carried out in vascular or reverberatory furnaces called anode furnaces. A new process for continuous copper fire refining has been proposed. The copper flows through two reactors in cascade, where is oxidized and reduced. The flow of a liquid copper through a ceramic packed bed increases the surface area and the rate of oxidation as well as the rate of reduction in the packed bed of charcoal. Mathematical modelling allowed for the design of a laboratory scale demonstration installation and industrial-pilot installation in Hernan Videla Lira Smelter (Paipote). The results have demonstrated the process feasibility and flexibility in operation.

Jan 1, 2009

By James Ball

The paper describes a new type of pump and related apparatus specifically designed to dredge sea-floor minerals from very great depths. The principle of operation of the dredging system is explained, and the factors which determine the equipment size and the power required for varying mining rates and depths of water are discussed. An estimate of the capital and operating cost of a commercial-scale mining system is presented.

Jan 1, 1968

By A. Aaltonen, S. Paloranta, H. Myllykangas

A property based dynamic model of flotation was built and validated for training purposes. The model is based on the work of the AMIRA P9 project. The recovery of each particle with composition and size is calculated in a given simulation step. The model takes into account machine and operational parameters such as air flowrate and froth height. The model was created using fullscale test data on Pyhlisalmi Cu-Zn-pyrite ore with flotation kinetics of multiphase particles determined. Simulation and validation shows that model can predict the dynamic behavior of the process accurately enough for training purposes.

Jan 1, 2009

By Keiji Watanabe, Hiroyuki Tobo, Yasutaka Ta, Hisahiro Matsunaga

Recently, effective utilization of by-product slag as aggregate for concrete has been expected from the viewpoints of depletion of natural crushed stone and suppression of environmental loads. We developed a new process for continuous solidification of blast furnace slag as coarse aggregate. In this process, molten slag is continuously poured into molds, and the slag is solidified at the thickness of 20–30 mm. The flow rate of the molten slag is 1 t/min, and maximum production per ladle is about 30 t. After solidification, blast furnace slag coarse aggregate (BFG) is produced by crushing and adjusting the particle size of the solidified slag. The new BFG has water absorption of less than 1%, and concrete containing the BFG has the same fresh property and compressive strength after 28 day as concrete using natural crushed stone aggregate.

Mar 1, 2018

By T. C. Boberg, R. B. Lantz

This paper presents a method for calculating the producing rate of a well as a function of time following steam stimulation. The calculations have proved valuable in both selecting wells for stimulation and in determining optimum treatment sizes. The heat transfer model accounts for cooling of the oil sand by both vertical and radial conduction. Heat losses for any number of productive sands separated by unproductive rock are calculated for the injection. shut-in and production phases of the cycle. The oil rate increase caused by viscosity reduction due to heating is calculated by steady-state radial flow equations. The response of successive cycles of steam injection can also be calculated with this method. Excellent agreement is shown between calculated and actual field results. Also included are the results of several reservoir and process variable studies. The method is best suited for wells producing from a multiplicity of thin sands where the bulk of the stimulated production comes from the unheated reservoir. The flow equations used neglect gravity drainage and saturation changes within the heated region. INTRODUCTION This paper presents a calculation method which can be used to predict the field performance of the cyclic steam stimulation process. The calculation method enables the engineer to select reservoirs that have favorable characteristics for steam stimulation and permits him to determine how much steam must be injected to achieve favorable stimulation. While the calculation represents a considerable simplification of physical reality and the results are subject to numerous assumptions which must be made about the reservoir, it has been found that realistic calculations can be made of individual well performance following steam injection. The duration of the stimulation effect will depend primarily on the rate at which the heated oil sand cools which, in turn, is determined by the rate at which energy is removed from the formation with the produced fluids and conducted from the heated oil sand to unproductive rock. A complete mathematical solution to this problem is a formidable task, and finite difference techniques would undoubtedly have to be used. The calculation method pre- sented here utilizes analytic solutions of simple related heat transfer and fluid flow problems. The method is sufficiently simplified that it can be used as a hand calculation, although the calculations are somewhat lengthy and laborious. For that reason, the analysis was programmed for an IBM 7044 digital computer. Well responses observed at the Quiriquire field in eastern Venezuela&apos; have been matched using this program after making suitable approximations for reservoir and wellbore conditions. One of the most valuable uses of this calculation method is to assess the effect of reservoir and proc-cess variables on the stimulation response. This paper contains results of several studies made of key reservoir and process parameters. Among the most important of these is the influence of prior wellbore permeability damage. If a well is severely damaged prior to stimulation, a higher stimulation response will be observed than if it is undamaged. If a portion of this damage is removed, a permanent rate improvement will occur. THEORY I)ES(:KJJ&apos;TION OF CALCULATION METHOD The process of cyclic steam stimulation is essentially one of reducing oil viscosity around the wellbore by heating for a limited distance out into the formation through the injection of steam. Suitable modifications of the calculation technique presented here can be made so that stimulation of wells by hot gas injection or in situ combustion can also be calculated. A schematic drawing of the heat transfer and fluid flow considerations included in the calculation method is shown in Fig. 1. In brief, the calculation assumes that the oil sand is uniformly and radially invaded by injected steam. For wells producing from several sands, each sand is assumed to be invaded to the same distance radially. In calculating the radius heated rn energy losses from the wellbore and conduction to impermeable rock adjacent to the producing sands are taken into account. After steam injection is stopped, heat conduction continues and oil sands with r < ra cool as previously unheated shale and oil sand at r > r, begin to warm. The effect of warming of oil sand out beyond r, has little effect on the oil production rate compared to the effect of cooling of the oil sand nearer the wellbore than ra. Thus, in computing the oil production rate, an idealized step function temperature distribution in the reservoir is assumed where the original temperature exists for r > rn and where an average elevated temperature exists for r < rn. The average temperature in the oil sand for the region r < rn is computed as a function of

Jan 1, 1967

By Nutter R. S.

A methodology has been developed for qualitative safety hazard evaluation and quantitative reliability analysis of mine monitoring and control systems. Detailed application of these techniques were made to two commercial monitor/control systems and to a West Virginia University distributed microprocessor-based system. A controlled environmental test was conducted on a set of one of the commercial system&apos;s outstations. A software reliability evaluation methodology was also developed and applied.

Jan 1, 1982

By Harald Vogel, Johannes Lachenski, Friedemann Koetzel, Sebastian Schnell

In this paper, a digital subsoil approach, a work-in-progress, will be presented describing the transformation from a classical 2D to digital 3D thinking process in the design of geotechnical structures. Certain pitfalls as well as lessons learned are described, and the reader can understand that the digitalization process of the design of geotechnical structures is always a problem-focused approach by creating systems for certain processes rather than setting rules or regulations. Three project examples are presented. Two of the presented project examples feature a heterogeneous geology distribution and made it necessary for the design of the foundations to work with 3D subsoil and 3D calculation models. However, the digital 3D design process in the third project, an inner-city excavation pit, is driven by the complicated boundary conditions making it necessary to work in a parametric 3D design space. All projects have in common, that new processes had to be developed. The paper concludes with a flow chart describing the process of the elaborated digital subsoil approach.

May 1, 2022

By Richard C. Corson

The new 9300 TPD sinter plant being built for China Steel Corporation is incorporating the latest computer technology for plant control systems. The control system will use a central computer and distributed micro-processors to control instrument loops and switching logic in the blending yard and sintering plant. All plant functions, including combustion and fan controls, will be controlled by remote microprocessors located throughout the plant, and connected by a communications link to the centrally located computer and control room. The design, programming, construction and operation of a microprocessor based control system presents new challenges to the control engineer. With microprocessors in the control system, more power exists in the individual control loop and many supervisory functions may be added at the loop level. The specification of the microprocessor system and the resolution of hardware design and control system design can lead to development of powerful systems capable of higher level control and optimization functions

Jan 1, 1981

By H. Herbert Hughes

ECONOMISTS have predicted that the present business depression ultimately may pay big dividends to industry through the cumulative savings resulting from technical improvements and merchandising advances that might never have been developed under normal conditions. Waste prevention is a sound medicine for economic ills. In theory, this prescription may be applied not&apos; only to raw materials, but also to labor, fuel, over- head, and other phases of production. Actually, how- ever, regardless of the efficiency of operating practices, waste is inevitable in the production of many commodities. The problem then becomes one of profitable utilization of waste rather than prevention.

Jan 1, 1932

By John A. Dresser

At a meeting of the Montreal Branch of this Institute in the autumn of 1928, the Honorable J. E. Perrault, Minister of Mines for Quebec, announced his intention to enlarge the Bureau of Mines of Quebec by the addition of a Division of Geology. The announcement further stated that the geological work proposed should be begun in the following field season, and that it should be on a substantial scale of not less than six field parties. The announcement was received with enthusiasm and much encouragement was held out for the success of the effort. It has been thought that the present meeting would be a suitable occasion to present a report of progress of this Division for the three years that have since elapsed. History This, of course, is not the first geological work to be undertaken by the Bureau of Mines. Prior to the establishment of the Division of Geology, the Bureau of Mines had not been unmindful of the need of geological research, but it had always lacked the means necessary to any sustained work. For more than 25 years the late J. Obalski was the Superintendent and the sole occupant of the Bureau. Yet, even then, Obalski, besides routine visits to mining districts, made a few exploratory trips along the north shore of the St. Lawrence river and one to Chibougamau, but without the equipment necessary to effective results.

Jan 1, 1932

By B. F. Dickerson

STRATEGIC METALS! Recently, this money accented cry has been heard in such diverse locales as Mining company boardrooms, Banker&apos;s offices, Stockbroker&apos;s quarters, Swindler&apos;s dens and Congressional committee rooms. (In some cases, these locales are one and the same). Is the strategic metals rush for real? Should it be? Our paper attempts to give a very generalized view of the subject for a few metals, points to a few potential, but generally overlooked sources of these metals, and offers conclusions based on our studies.

Jan 1, 1981

By Karoly (Charles) Kocsis, Kyle A. Scalise

Understanding the climatic conditions in underground mines is necessary for efficient ventilation design, cost savings, and to ensure the health and safety of mine workers. Large volumes of ventilation and climatic data including air volume, barometric pressure, dry bulb temperature, and relative humidity were collected at active underground precious metal mines in Nevada, which allows for the determination of wet bulb temperature and other key parameters. Through the utilization of neural networks, the wet bulb temperature at the bottom of the intake shafts is predicted, while taking into account the “thermal flywheel effect” (TFE). Wet bulb temperature is one of the most important climatic parameters to model and understand because it significantly affects the work conditions and the cooling capacity of the ventilating air. The accurate prediction of the dry bulb and the wet bulb temperatures at the bottom of intake shafts is critical when assessing the climatic conditions in future underground mines and deciding onwhether a cooling system is needed to assure adequate working conditions throughout themine. By utilizing accurate predictions of wet bulb temperatures and other climatic parameters, mine personnel will be safer as reported by Bluhm et al. (2003), and a more accurate ventilation design can be achieved resulting in major cost savings for underground mines.

Mar 3, 2021