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By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996

By Ying Lu, Jeffrey C. Johnson, Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

Energy dissipation and fragmentation of rock is of interest for mine-to-mill operations in order to understand breakage and to minimize energy consumption during blasting at the mine site, and comminution at the processing plant. In this regard, high velocity impact breakage of long granite cores, called bars, has been studied with instrumented strain gages to follow the energy dissipation gradient along the bar length resulting from the strain waves generated by impact. As a result of high velocity impact, three zones have been identified (fragmentation, fracture, and elastic) and these three zones have been characterized in 3D using X-ray tomography. The fragmentation zones of the granite bars were studied in detail to describe the particle size distribution and the particle shape characteristics. Finally, the experimental energy dissipation for the fragmentation zone was found to be in close agreement with the expected energy calculated from the Bond work equation, if the anisotropic granite particles are defined by length rather than by sieve size.

By E Marambio, R Brändle, G Fischer, G von Rickenbach, M Fuentealba, L Burgos, R Luis Fonseca

In underground excavations, under high stress conditions, ground support systems must provide safe and effective response to dynamic events. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the back analysis through numerical methods (central difference and Newmark’s method) of a ground support system tested with a double dynamic impact in 2019 is presented.

Apr 26, 2022

By R. E. Nelson

The Alton Coal project, located in south-central Utah, lies at one point just over six miles from Bryce Canyon National Park. This region of the southwestern United States has been called the "Golden Circle" of national parks and monuments. Can a mine be inserted into this region so that it does not intrude on this spectacular landscape? The Alton Coal Project is a proposed surface coal mine designed to serve as the fuel source for the Harry Allen Power Plant, a 1,000 megawatt generating station planned for a site 25 miles northeast of Las Vegas, Nevada. The mine and the power plant will be connected by an underground pipeline through which coal will be transported in slurry form.

Jan 1, 1988

By Diler Katircioglu-Bayel

This study aims to investigate the effect of combined mechanical and ultrasonic milling on the size reduction of talc. First, the talc sample was wet-ground in a stirred media mill for five different lengths of time (30, 60, 90, 120 and 150 min), and the optimum result was subsequently achieved with treatment by ultrasonication. The effects of amplitude (20, 35 and 50 µm), solid ratio (2.5, 5, 7.5 and 10 percent), and sonication time (60, 120 and 240 min) on the sizes of the final product were investigated. The pre-milling by wet grinding caused a decrease in the grinding resistance of talc. Sequential ultrasonic treatment, which was applied to the talc sample, generated smaller particles in comparison to those acquired by stirred media milling alone. Experimental results were assessed based on the product particle size (d10, d50 ), reduction ratio and specific energy consumption. Submicron particles prepared by ultrasonic treatment were highly stable compared to stirred media milling alone as investigated in terms of particle size. In addition, the effects of mechanical and ultrasonic milling on the structural properties of talc particles were characterized by X-ray diffraction (XRD) analysis.

By Dr. Richard F. Coon, James D. Mavis

Risks and abatements associated with preliminary reconnaissance, plugging and filling, and maintenance of perched mine water pool are examined. This case history showed that the initial appeal of portal plugging was replaced by concern over potential environmental hazards when details of implementation were investigated.

Jan 1, 1992

By Emily Muto

LiDAR technology has made it possible to map large areas of underground mines accurately and rapidly in three dimensions. MSHA Technical Support began implementing LiDAR technology in conjunction with the Agency’s Pillar Collapse Initiative, using scans to determine width-to-height ratios (w/h) of pillars adjacent to mass collapse areas and to conduct risk assessments for global pillar stability in U.S. stone mines. This work quickly expanded to include change detection, such as measuring many pillars to show which are deteriorating over time. Change detection has also been used in ground falls and squeeze areas to see if they have continued to propagate. LiDAR technology supports accurate data acquisition of unstable mining conditions from safe distances. For example, once the LiDAR scan has been processed, it can measure roof fall cavity heights and volumes with the user at a stable ground location. Some LiDAR scanners can collect geologic data, such as joint orientations.

Jun 25, 2024

By J. M. Keating, R. L. Wiegel

Those processing plants which depend on flotation for their mineral separations are always looking for reagents which are cheaper, more selective or in some other way may provide improved economic performance. This paper describes the rationale for and some results from applying a statistically based approach to reagent testing in those flotation plants which still rely on experienced operators for manual flotation control.

Jan 1, 1986

By W. A. Lawruk, L. J. Wilson, D. E. Stief

The Tower mill is a vertical stirred mill using steel balls or pebble grinding media. This device is designed for fine grinding at significant power savings when compared to conventional tumbling mills. This paper describes the machine and its operation, application, and performance for wet grinding.

Jan 1, 1988

By Lawrence S. O’Rourke

Pricing for tantalum raw materials experienced explosive increases in the period 1978-1979, and-similar declines over 1980-1982. The causes for this are examined. Negative effects on the industry are highlighted. Analysis is provided of subsequent structural changes within the industry which minimize probability of future pricing excursions. Data on markets, sources of material, and outlines of concentration and extractive processes are reviewed. The conclusion is reached that expanded sources, future flat demand, and a broader international base of industry participants are principal forces in this restructure. Flat demand is reviewed as a function of increasing application of tantalum, but in more cost effective forms. This is driven by technical advance, notably in electronics applications.

Jan 1, 1986

By J. Manrique, B. Bustamante, P. Altamirano, J. Mendoza, J. Reyes

With no doubt, Peruvian mining potential is great as well as the energetic one. Unfortunately, this potential is threatened by social unrest. Several methods and strategies from different standpoints have been rehearsed with respect to unrest in Peru, however, the problem goes on without getting the right conflict interpretation and most of all, effective solutions are not achieved. The mining unrest dates from ancient times and has not always had the same stages nor the same demands. In the 20´s and 30´s, conflicts focused on workers’ rights and demands. In the 70´s, conflict focused on mines nationalization that were under foreign control. In the 80´s, conflicts took place because of requesting better wages, better working conditions, better mining profits distribution and more investment in communities that surround mining projects. It is very important to highlight those transversal demands such as land purchase, agricultural property, impacts and water reduction as well as pollution, impact on water systems and disappearance of springs have always been present over the historical period.

Mar 2, 2022

By Z. Kokesz

The following paper presents the results of geostatistical studies of the selected hard-coal deposits in Poland. Geostatistical methods were applied mainly to the characterization of variability structure of the coal seams thicknesses as well as sulphur and ash contents in the coals. Results imply that the accuracy of coal reserves estimations can be improved if kriging method is applied. Kriging allows predicting more precisely the values of such parameters as thickness and sulphuring content.

Jan 1, 1993

By D. B. Gentzler, J. L. Kohler

A method of monitoring production information (raw tonnage and machine state) from each working section has been developed. The method is based on the sensing of electrical parameters in each section load center, and the reporting of this information through the existing mine-wide monitoring system. A decision-theoretic type of pattern classification technique has been used to define the machine states. The basis of the method is presented in this paper, along with a proposed hardware and software implementation scheme. Information issues central to the development and use of the proposed production monitoring system are also discussed.

Jan 1, 1990

By John W. Tieman

Coal is a term applied to vegetable matter (trees, grasses, etc.) which was subjected to heat and pressure through geologic ages. This resulted in a change in both the physical and chemical properties. Because its chemical composition is variable, geologists classify coal as a heterogeneous mineral rather than a homogeneous mineral. Peat represents the initial, unconsolidated stage in the development of coal. This coalification continues with time and the application of temperature and pressure to lignite, subbituminous, bituminous, and anthracite toward the theoretical graphite end member.

Jan 1, 1981

By R. Perlo

"INTRODUCTION Peoples’ and operators’ safety in construction are tightly linked to the engineering choices, as much as the necessity of reducing time and costs of realization. Therefore, it is of paramount importance to address them properly from the earliest stage of the design, identifying the risks connected to the work and the variability of such during the different phases of the project. Risk is often measured as the expected value of an undesirable outcome. Regarding to occupational safety and health, the risk is the likelihood that a person may be harmed of suffers adverse health effects if exposed to a hazard. This combines the probabilities of various possible events and the assessment of the corresponding harm into a single value. However, the actual occurrences are often more complex than a single binary possibility case. In a real case scenario, with several possible accidents, the total risk is the sum of the risks for each different accident, provided that the outcomes are comparable. The semi-automatic tunnel support system along with its erector machine proved to be a solution with improved structural performance, able to reduce the time and yet to deliver an enhanced, quality-aware and safer working environment for the operators. The implementation of the system provides the engineers, the contractors and the owners with an effective alternative option shortlisted in 2015 for the ITA Award for the Safety Innovation of the Year. In a market industry driven by safety and time constrains the efficiency shall be the ultimate goal, in order to provide solutions able to negotiate with the most challenging ground conditions. In this paper, the authors describe the recent developments on regard of this whole new tunnel support system, including design approach and presenting related case histories OFFSETTING THE RISKS Considering the above factors, from the manufacturers’ point of view, an effective way to limit the construction risks is to focus on the material and technological characteristics, their application and the risks related to them including any residual risks. Finally addressing the construction needs also involves time and cost-effective solutions. The path to follow is an integrated approach where the efficient management of the risk is supported by a flexible, user-friendly, and time effective product that is able to provide a safe, reliable and viable solution to address the construction requirements. Therefore, in a market sector driven by safety and time constraints, the efficiency is a key goal, in order to avoid redundancy and yet to deliver a safe working environment able to meet the construction schedule. The safety of all the parties involved is given by stable working conditions, either for the workers, or the operators and eventually the public. Therefore, the solutions provided should ‘strengthen’ the overall condition and such “to limit or to reduce the deformations within acceptable designed limits and to prevent [the tunnel] to collapse” [1: Clause 207.1.4]."

Jan 1, 2018

By DING TANG, JINGHE CHEN, Shuiping Zhong, CHEN KUANG

The Zijinshan gold-copper mine, located in Shanghang County, China, is a porphyry-type, low-grade ore deposit with a geological profile of upper gold and lower copper. Despite its low-grade nature, it has become one of the largest in production scale and most profitable nonferrous metal mines in China, which can be attributed to the successful application of hydrometallurgy as well as proper engineering design. A large-scale, open-air cyanide heap leach has been successfully implemented to recover gold under the humid and rainy weather conditions of southern China. Furthermore, according to the gold ore characteristics, a combination of gravity separation, carbon-in-leach and heap leaching processes was developed to improve gold recovery. In terms of copper extraction, copper ore of a grade higher than 0.25 percent is fed to the flotation plants to produce copper concentrate (gold is also enriched here), while copper ore of a grade lower than 0.25 percent undergoes heap bioleaching followed by solvent extraction and electrowinning to produce cathode copper. Additionally, a unique bioleaching system has been established at the Zijinshan Mine: low operating pH (0.8~1.0), high concentration of total soluble iron (~50 g/L), high temperatures (45~60 °C) and low activity of microorganism (~104/mL) in the pregnant leach solution (PLS). This review paper summarizes the practical experience acquired in developing the Zijinshan gold-copper mine and could be of use in other gold and/or copper plants.

By P. Verhoeven, G. Hefter, P. M. May

The dissociation (ionisation) constant of hydrogen cyanide, pKa(HCN), has been measured by high precision glass electrode potentiometric titrations in saline solutions containing up to 5 mol/L sodium chloride. The dissociation constant of water that is necessary for the calculation of pKa(HCN) has also been measured. In saline solution, and in contrast to literature values, pKa(HCN) changes considerably at both high and low ionic strengths as a result of changes in activity coefficients. In addition an equation is presented, using literature data, that describes the variation of pKa(HCN) with temperature up to 150°C. The significance of the changes in pKa(HCN) for optimising the pH of alkaline cyanide gold recovery streams is briefly discussed.

Jan 1, 1991

The last twenty years of development in Process Mineralogy are reviewed. Since the milestone review by Henley in 1983, which projected the concept and suggested closer working relations between mineral processing and mineral science, the second generation (1983-2003) has made significant progress. Examples are to be found in improved sampling and high-confidence flotation testing, and in automated quantitative mineral measurement. The recent addition of end-member studies has provided a clearer view of the overall ore mixture milled from its constituent geological components. In all, better predictive abilities have resulted from these improvements to Process Mineralogy. These improvements have led to more significant business impacts in mineral resource characterization, and in optimization of existing concentrator operations.

Jan 1, 2004

By J. W. Merks

Applied statistics provides scores of powerful tests and techniques that are widely used and abused in science and engineering. The variance is the basic measure for variability, precision and risk. The formulas for the variances of the arithmetic mean and the weighted average are derived from the variance of a general function, as defined in probability theory. The requirement of functional or mathematical independence in probability theory translates into the concept of degrees of freedom in applied statistics. Geostatistics is the only variant of statistics in which functional dependence and degrees of freedom are irrelevant. This paper examines whether such basic elements of probability and statistics can be ignored with impunity.

Jan 1, 1997

By T. M. Barton

Coal mine bumps the violent failures of over-stressed coal', present a safety hazard to miners when mining is conducted in deep, bump prone coal mines. Two different longwall gate entry systems were evaluated in a Southern Appalachian coal mine located in the Pocahontas No. 3 Coalbed under approximately 610 m of overburden which included a massive sandstone member. Both gate entry systems employed a center abutment pillar flanked by yield pillars. The original design employed a 24.4 m square abutment pillar' while the new design employed a 36.6 by 54.9 m' abutment pillar. Rock mechanics instrumentation data analysis and in-mine observations indicated that this increase in abutment pillar size significantly decreased bump potential. The new design in worse case conditions increased effective bearing area 62 pct with only a 9 pct increase in gate entry system width and eliminated face bumps that wer7 experienced with the original gate entry design.

Jan 1, 1991