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By Dennis A. Giardino, Leonard C. Marraccini

This paper surveys noise levels, noise exposure patterns, and frequency spectra found in the mining environment; the effects of mining noise on the working population; and the quantification of hearing loss in the coal mining industry. Federal mining noise regulations and the present state of the industry, with respect to noise control technology, are discussed. Examples of proven noise controls for mining are included along with measured noise reductions.

Jan 1, 1986

By Balesh W. Konda, Andrew B. Cecala

Face ignitions occurring during longwall mining are increasing each year and are expected to continue to increase as deeper and gassier seams are mined. Effective methane monitoring strategies are needed to supplement techniques developed either to control the ignition sources or to dilute the gas to an acceptable concentration. Present monitoring strategies do not always detect dangerous concentrations as rapidly as they should. In a number of instances, dangerous concentrations have been observed at the shearer, but are diluted to acceptable levels when measured at the tailgate monitoring location. To effectively monitor and control methane concentrations, methane liberation and emission patterns must be identified. This need has led to a joint research effort between the Canada Centre for Mineral and Energy Technology and the United States Bureau of Mines. By combining the knowledge and experience of both organizations, the methane hazard facing underground longwall operations can be addressed more effectively. A comprehensive plan was developed to monitor methane levels throughout the panel and for an entire longwall mining cycle. In June-July 1986, a case study was performed at the Cape Breton Development Corporation's Lingan colliery in Sydney, Nova Scotia. This initial study was performed on two advancing longwall panels. Methane concentrations and flow patterns from this study are described in this report. A similar study is planned on a retreating longwall panel.

Jan 1, 1987

By Frank F. Aplan, Edward C. Dowling, Richard R. Klimpel

Several series of time-instantaneous samples were taken on a cell-by-cell basis in the flotation circuits of the Pinto Valley, AZ copper concentrator. These samples were used to calculate mass flow rates throughout the circuit using standard, deterministic metallurgical formulae and also a variety of more statistically oriented techniques. Because of the magnitude of the errors associated with the individual cell samples, the standard metallurgical formulae are not sufficient. Consequently, it is necessary to utilize some type of statistical technique capable of distributing the individual cell sample errors in such a way so as to provide a physically useful mass balance for the entire circuit. This paper explores the use of linear and least squares programming as one technique to providing credible mass balance calculations. For linear programming this was done by distributing the error using two different criteria involving specific linear programming formulations: least absolute sum minimization (which assumes an underlying double exponential distribution error structure) and minimax (which minimizes the maximum absolute deviation and assumes an underlying rectangular distribution error structure). These results were then compared to the more standard formulation of minimization of the sum of least squares which assumes an underlying normal distribution error structure. The least absolute sum approach was particularly attractive due to its simplicity of use and the ease in which repetitive calculations can be done with no user intervention.

Jan 1, 1990

By D. W. Fohlen, B. A. Filas

The International Finance Corporation (IFC), the private investment arm of the World Bank Group (WBG), requires all IFC-financed projects to comply with its environmental and social policies and guidelines. IFC's review process involves an environmental and social assessment and the implementation of an Environmental Action Plan (EAP) that will set forth the necessary actions to bring the operation into compliance. This paper provides an overview of the environmental and social policies and guidelines that apply to mining projects and examines how WBG/IFC policies and guidelines are applied to mining projects in developing countries. In addition, it includes a review of the increased emphasis IFC is giving to social issues over the past several years based on the existing WBG policies. IFC’s process for the environmental and social review of proposed investments is briefly discussed. The paper focuses on how IFC emphasis has shifted from the traditional environmental and impact mitigation analyses of a few years ago to the integrated social and environmental awareness, action (EAP), and implementation programs (social plans) required today. Today, IFC's focus is to promote sustainable development by investing in projects that directly benefit local communities and the environment. Examples of these changes will be highlighted by a review of recent investments located in West Africa. The goalposts have not moved, but the rules of the game have become tougher.

Jan 1, 2001

By C. E. McFarland, N. W. Kirshenbaum

Cortez Gold Mines is located about 75 miles southwest of Elko, NV. Activity in the mining district dates from 1862. The current operation developed from a 1963 joint venture of Webb Resources, The Bunker Hill Company, Vernon F. Taylor, Jr., and American Exploration & Mining Co. Three years later, the USGS discovered gold on the property following a regional geochemical survey. Drilling in 1966 and 1967 identified 3.4 million st of oxide ore grading 0.28 oz Au/st, and a 1700 st/day countercurrent decantation mill was commissioned in 1969. Heap leaching started in 1971 on low grade ore and continues to the present. The mill was shut down in 1976 following exhaustion of known oxide reserves. Mobile equipment was sold and the proceeds committed to local exploration. In 1980, a new plan of operations was developed starting with existing low grade and newly discovered mill ore. The mill resumed operations in 1981 and has been operating to date. A series of metallurgical innovations, culminating in the commissioning of a new fluid bed roaster in the summer of 1990, has enabled treatment of a series of increasingly refractory ores. Current partners in the venture are Kennecott Corporation, Vernon F. Taylor, Jr., and Placer Dome U.S. Inc., manager of the operation. Idaho Mining Corp. holds a 7.5% carried interest.

Jan 1, 1992

By R. H. T. Garnett

Reserve estimation is a process that commences with sampling and culminates in the issuance of a reserve statement. The tin, gold and diamonds that occur as marine placers on the continental shelf are low grade with very erratic mineral distributions. Sampling, using a variety of special equipment, determines the extent and grade of the mineralization. The sample size is important, especially for diamonds. Together with the sampling density, it determines the accuracy of the grade estimate. Bulk sampling is a confirmatory process. The choice of mining equipment, either new or developed from onshore activities, dictates the unit costs, the cutoff grades and the selectivity of extraction. Thus, the size of the blocks that comprise the mining plan and the reserves are determined. A variety of estimation methods of different reliability are available, with the most sophisticated being kriging. Dilution and losses during mining must be taken into account in estimation, and a grade-volume curve should be constructed. Diamond deposit estimation also involves an extra variable, the dollar value of the stones. During and after mining, essential feedback on the accuracy of un estimation may be given by the RIE factor and by a mineral balance. Reserve estimates are required for several reasons and may be subject to public disclosure. The use of the correct definitions is, therefore, important.

Jan 1, 1999

By A. M. Elmherig, M. R. Sunu, R. N. Singh

The presence and orientations of fractures and discontinuities in rock masses exposed in a surface mining excavation are likely to have a great influence on both slope stability and blasting efficiencies. The classification of rock materials requires detailed investigations which are of interest to the design engineer. In designing a safe mining excavation, an engineer must take a number of decisions regarding face support and orientation based on the evalu¬ation of local strength and structural conditions encountered. The description of rock masses requires information additional to the properties of the rock material, discontinuities and other characteristics of engineering importance. Such information involves the acquisition of the following data: The description of the rock mass with reference to major geological structures. The orientation, nature, spacing and persistence of discontinuities. Degree of weathering. A critical review of rock mass classification systems and their application to surface mine excavation design and stability analysis is presented. The field investigation techniques for collecting rock mass data are described together with the techniques of analysis and presentation of data. Laboratory tests are carried out to determine intact rock strengths and deformation parameters of rock. The paper presents two case studies from the British hard rock surface mining industry to illustrate the application of the rock mass classification systems to stability analysis and excavation design.

Jan 1, 1986

By Stefano Colombelli, Nicola Bona, Gabriele Eccher, Luca Schiavinato, Paolo Cucino, Domenico Nave

"BIM technologies provide tools and processes to effectively support the entire life of an infrastructure, from strategic planning to maintenance. As a consequence, infrastructure design processes currently make frequent use of BIM tools. This paper describes the BIM oriented design of the underground railway extension in the metropolitan area of Catania. The paper highlights the design process and the chosen BIM tools considering the boundary conditions characterizing the project, i.e. basic information missing in the final design project, need of coordination between different design disciplines and designer companies, and, finally, need for a flexible design approach able to adapt to changes occurring during design development. INTRODUCTION The underground railway extension in the metropolitan area of Catania is composed of two lots of approximately two km each, namely “Stesicoro-Aeroporto” and “Nesima –Misterbianco”. Works to be realized are: •,Main tunnel: mechanized tunneling using a TBM-EPB machine, for the entire length of the lot; •,Underground stations: San Domenico, Vittorio Emanuele and Palestro, conventionally excavated as enlargement of the TBM tunnel after the partial demolition of precast segments; •,Ventilation and emergency shafts: connecting seven tunnel levels to road level on Stesicoro-Areaposto lot, six on Nesima-Misterbianco lot; •,Additional structures such as technical rooms and parking lot; •,Electric Substation at Monte Po' stop; •,Temporary works: TBM launching and arrival pit to be dismantled at the end of the works."

Jan 1, 2016

By Richard C. Sale

INTRODUCTION The topic of the paper is to discuss the use of micro computers in the construction industry. I will first discuss the present situation of the PCs in our industry followed by a discussion how Guy. F. Atkinson has integrated the PCs into it's organization. I will close with some general comments that any organization should review in order to enhance the use of their PCs both at the job sites and home office locations. PRESENT SITUATION OF THE PCs IN OUR INDUSTRY Today, the possible number of combinations that can be obtained when bringing together the available models of PCs, with their peripherals and software, is astronomical. With this array of equipment that can be bought, plus the new and possibly better equipment that is being put on the market almost daily, it is indeed a very difficult task for an organization to know how to invest its money in computer equipment. At the job sites, the work is fast paced with little time available to fully learn what the PCs can do to help with the required paperwork. I am still waiting for the day when someone has to tell the superintendent at the job site that he cannot start pouring concrete or shoot the next round because no one can get the computer to work.

Jan 1, 1987

By Jerry M. Whiting, Samuel Frimpong

Superior ventures selection and the subsequent management of their development and production are crucial in the competitive environment of the upstream minerals and energy industry. An important element of this chain is the management of uncertainty and risk dynamics. In the world of faster and more complicated technological and environmental changes, international competition and commodity market dynamics, thorough and sophisticated valuation must be carried out to establish a venture's value and return on investment. Thus, managers and investors must use methods that respond to market dynamics, investment and feasibility study options and provide relevant information for strategic investment decisions. Conventional methods have no built-in procedures to help investors analyse these options. Modern financial methods based on the dynamic arbitrage theory overcome these and other limitations of conventional methods. In this study, dynamic arbitrage theory has been used to formulate 3D parabolic differential equations that govern the stochastic processes of a copper mining venture with ongoing feasibility studies. The alternate direction implicit algorithm is used to solve the numerical approximations of the differential equations and their boundary conditions. Phase dynamics of the venture have been analysed to provide investors the appropriate timing for strategic investment decisions. The study also shows the amount and value of appropriate feasibility studies required to maximize the value of the mining venture.

Jan 1, 1996

By Charles N. Speltz

The cost of transportation of industrial minerals frequently is higher than the cost of the product. When a mine, industrial-mineral plant, or customer is served by a single railroad, because of the lack of competition, that railroad may in- crease rates and/or reduce service so that the economics of that mine, plant, or customer are affected adversely. Transloading of industrial minerals from rail-to-truck or truck-to-rail to improve economics and sales of product is not a new concept. However, transloading to create competition and reduce freight costs or to improve service is a relatively new concept brought on by the recent mergers of many of the main-line railroads, both in the eastern and western United States. For example, in 1998, with completion of the Burlington Northern/Santa Fe (BNSF) and the Union Pacific/Southern Pacific mergers (UPSP), the western United States has only two main-line railroads. The industrial-mineral producer, to reduce the cost of transportation or increase the level of service, must evaluate potential transloading opportunities in light of higher prices and reduced service brought on by reduced railroad competition. This paper discusses industrial-mineral transloading and examines the case history of the Tucker Hill perlite project in southern Oregon. The Tucker Hill project is a classic study of industrial-minerals transloading where the project would have failed without the transloading.

Jan 1, 1999

By V. Rastogi

Surfactant-based bactericides are able to control acid formation in sulfidic materials such as pyrite and sulfidic ores, thereby helping to abate acid rock drainage. Bactericides are used in the following two ways: as periodic or continuous spray treatments for the prevention of acidification of material actively handled and moved and in controlled-release form for reclamation. Site-specific bactericide treatments are designed for active sites and reclamation. Results from two active coal refuse sites show that acid production can be reduced by 88% or more. Results from reclaimed sites show that bactericide treatment can be more effective than the addition of alkaline materials such as limestone and can reduce acid production from 3,500 to <30 ppm. The controlled-release-pellets treatment outlasts the life of the pellets, as shown by a study of a site now 10 years old A single treatment sets up a change in site microbiology to replace acid-producing Thiobacillus ferrooxidans bacteria with heterotrophic bacteria and creates a stable site without the need for further treatments. A secondary beneficial effect of bactericides is on revegetation, and biomass from treated areas is almost 10 times that from areas not treated with bactericide. Depending on the application, bactericide treatment can be cost effective upfront and certainly long-term, compared to the perpetual water treatment that could be required, even after productive use of the site is completed

Jan 1, 1997

By Anitava Ghosh

A computer program has been written to simulate ground vibrations induced by multiple- hole surface blasts. The program is an inexpensive and relatively easy to use tool for predicting the principal blast vibration characteristics that determine damage and annoyance potential: peak particle velocity, frequency content and pulse duration. The program generates a complete ground motion history by superposing, at any surface position, the vibrations induced by each individual explosive charge. It requires specification of (hence allows accounting for) the blast geometry, initiation sequence (including random delays), position with respect to blast, pulse characteristics induced by each charge, and propagation laws. A methodology is outlined to determine the necessary variables either on the basis of site investigations (e.g.,velocity, attenuation, single-hole input pulse), or by back-calculation from measured blast vibration records. The latter procedure has been applied to blasts from two coal strip mines. Main difficulties encountered are backcalculating individual input pulses, propagation (especially dispersion) parameters and delays. A normal distribution of delays, based on published results, has been shorn to influence the results and the response of a single degree of freedom structure significantly. Broadening of the wave types included, improved input pulse determination and propagation laws, and more detailed verifications with field results are required in order to make the program more directly applicable to practical situations.

Jan 1, 1986

By Takeshi Tanaka, Shinya Ono, Tsuyoshi Kato, Masaji Kato, Yuusaku Tominaga

The knowledge of the macroscopic characteristics of a ventilation network is of fundamental importance for taking counter- measures to increase air quantity in-specified branches, such as those corresponding to working faces at advancing entries or longwall panels. Because the ventilation characteristics are inherent properties of each mine, it takes a long time for an engineer to accumulate experience on how a specific regulator may affect the air quantity in a specific branch of a mine with a complicated ventilation system. A computer-simulation training system, based on the macroscopic ventilation characteristics, is presented in this paper. When a trainee selects a specific condition from five regulator option (closed, almost closed, slightly open, half open, open), the change in air quantity for a network branch is indicated by the color allocated to the ratio of the new air quantity to the old or planned air volume. After the ventilation simulation, the colors in the specified branches are defined by using the fuzzy set theory. The trainee continues practicing the selection of closed/open conditions for different regulators until each of the specified branches is displayed in good state of airflow. The ventilation net- work of the Horonai coal mine is used as an example of the training system to control air quantities in six working faces with 33 regulators.

Jan 1, 1996

By Steven Johnson

The regulatory landscape has changed considerably since the first passage of Oklahoma&apos;s land-reclamation requirements in 1968 (Open Cut Reclamation Act of 1968). The Oklahoma Legislature revised the reclamation requirements in 1971 with passage of the Mining Lands Reclamation Act. With the passage of this Act, the Legislature empowered the Oklahoma Department of Mines with jurisdiction for permitting and regulatory authority over non-coal (industrial-minerals) mining operations. This act required all operators to file with the State, through the Department of Mines, a written application for a permit to engage in non-coal mining. Each application consisted of a mining plan, which included location maps of the proposed mining area along with a reclamation plan for the area to be covered. Additionally, a reclamation bond is required prior to issuance of a permit to ensure that the site would be reclaimed. Since 1971, the Act has been amended to include public notification and public participation in the review process of any application. Also, the operator can request that the Department review the mining plan based on the Life Expectancy of the mine, instead of the original one-year plan (HB 1409 in 1993). Even though the operator is granted a mining plan tied to the "Life Expectancy" of the site, the permit is reviewed annually for compliance as required by law.

Jan 1, 1999

By M. Misra, I. Anazia

The dispersion of oily collector has a significant effect on the flotation recovery of ultrafine coal. Generally, reagent dispersion is accomplished by mechanical mixing and/or ultrasonic agitation, followed by direct addition of dispersed collector into the flotation cell. Such dispersion and reagent addition techniques are invariably inadequate and nonselective. A new collector addition technique involving gas phase transport of atomized collector has shown improved results when compared to conventional reagent addition techniques. This technique involves atomization of the collector into the air stream. Under these circumstances, an aerosol is introduced into the flotation cell. Initially, the oil is dispersed within the air phase (continuous with respect to oil), and the air phase is dispersed within the pulp (continuous with respect to aerosol). In the flotation cell, the atomized oil droplets coalesce on the bubble&apos;s surface and create a de facto oil-encapsulated bubble. This approach provides excellent dispersion, increases selectivity, and, most significantly, increases the flotation rate of ultrafine coal. Atomization of collector/frother combinations yielded improved flotation recovery and maintained near uniform froth levels, which is a desirable feature in coal flotation. Microscopic examinations of the attachment of oil- coated bubbles at a coal surface were conducted by attachment time and contact angle measurements. Oil-coated bubbles attach at significantly faster rates and with a higher contact angle than oil-free bubbles.

Jan 1, 1988

By A. English, Edward Martinez, L. A. Haas, N. W. Johnson, Harrison Copper, M. E. Tawil, C. C. Harris, G. V. Jergensen, D. Halbe, M. P. Amsden

Declining US ore grades along with skyrocketing energy, materials, labor, and regulatory costs underscored the urgency for technological innovation in the mineral processing area. Re¬liance on the scale-up and automation of unit operations was the sector&apos;s primary battle plan. Debate continues on the upper size limit of concentrating plants and whether process controls should be centralized or distributed in the mill. In the materials handling area, the economics of large-scale and mobile systems, particularly conveyors, were well documented in the literature. Comminution, the most costly and energy consuming area of the processing flowsheet, saw improvements in process controls and liner designs. The trend toward larger grinding units stalled somewhat during the year owing to some operational problems at commercial plants. Research and development of apparently less expensive physical separation processes-that also boast recovery of cleaner and more environmentally acceptable products -gained momentum during the year. Because of escalating capital cost requirements for new plant capacity, the year saw a greater interest by mill designers to re-examine existing capacity. The focus here is clearly to modify or retrofit unit operations with more efficient components as an alternative to installing more costly new equipment. The problems facing the processing sector during the 1970s can be expected to continue in the decade ahead. Technological gains from scale-up and process controls appear

Jan 5, 1980

By A. E. Hall, D. M. Mchaina

This paper outlines a proposed research project to investigate secondary sulphide ignitions. Sulphide dust explosions have resulted in loss of production and considerable capital and equipment replacement cost in Canadian mines. The practical application of laboratory test results to actual mine situations presents a complex problem and is a field requiring immediate investigation. The factors contributing to the outbreak of sulphide ignitions are not clearly understood. This indicates a need for future research to study the influence of blasting parameters, exhaust temperatures, and dust characteristics on secondary ignitions at source. The aim is to establish realistic quantities for each of the parameters and develop a model that will incorporate field and laboratory quantities. It may be possible to predict outcomes of sulphide ignitions when the parameters are known. It is also planned to study the techno-economic feasibility of the preventive and control methods. One aspect of planned future research requires quantification of some terms by obtaining measurements of pollutant concentrations and size distribution of the airborne dust in an underground environment immediately after a main blast. A blast-proof aerosol sampling package to measure the source term will be designed. This sampling package will consist of a sampling section and a shield which will be capable of withstanding a blast explosion. The accuracy in measuring the variables and combination of variables will be the main focus in this proposed study.

Jan 1, 1987

The present study refers to passive systems for the treatment of acidic liquid effluents emanating from mixed-sulphide mines by means of an-aerobic compost wetlands. An effort was made for the thermodynamic study of the chemical systems that are involved in the reactions during the simulation of this specific system using laboratory columns and a pilot scale application. The substrate used was a mixture of cow manure, a high alkalinity organic substrate and chestnut woodchips, while the synthetic solutions prepared for the laboratory experiments contained the three basic metal contaminants i.e. Fe, Zn and Mn. The precipitation mechanism of the contained metals and the form in which these are precipitated was therefore investigated by constructing the equilibrium phase diagrams (Eh-pH diagrams) of the Me-S-C-H2O systems. Based on the experimental results from laboratory and pilot scale tests the stability conditions of the chemical species taking part in the aqueous solutions were also determined and verified with the thermodynamic data available. The thermodynamic analysis of the system was performed for ambient temperature, which is the prevailing temperature on field constructed compost wetlands. Results were further validated with the results obtained by the application of a five step sequential extraction procedure in the remaining substrate in order to determine the form in which the metals were precipitated.

Jan 1, 2006

By W. Ter-Minassian

Besides the question of the stability of the roof and walls, one of the main problems encountered with tunnelling and shaft-sinking through the soft ground of alluvial origin forming the sub-grade of most large towns is settlement. Public transport and road tunnels in town centres are particularly affected, as they cannot generally be designed at any great depth for several reasons, such as the fact that ventilation shafts and access to the surface by means of stairs, escalators, lifts, ramps and so on must be fitted into the limited space available and are therefore costly, and because of the difficulties of driving below the water table. It is for this reason, coupled with the need for wide radius curves, that tunnels now so often pass close under buildings and monuments which must not be exposed to any risk of damage from subsidence during excavation. Grouting is the usual method used for consolidating soils, improving their strength and making them less compressible, but it is itself liable to cause heaving and cracks in the buildings above and has many other attendant dangers, including continually revised estimates which are the reason for the often inordinately high costs met with in urban tunnelling to-day. The mechanics of the problem have been studied and it has been found that a fraction of the total settlement is

Jan 1, 1997