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By K. N. Han, P. B. Queneau, A. Stojsic, M. J. Collins, V. J. Ketcham, R. M. G. S. Berezowsky, W. D. Vardill

The bulk of the ore found in the Lihir Island deposit is refractory in nature, with the gold contained in auriferous pyrite. In support of an evaluation of the development of this deposit by Kennecott (a wholly owned subsidiary of RTZ) and Niugini Mining Ltd., testwork has been carried out at the Sherritt Research Centre to demonstrate the amenability of the Lihir ore to pressure oxidation pretreatment to liberate the refractory gold. The results of pilot plant treatment of the Lihir ore in a continuous circuit with a feed rate of between 10 and 30 kg/h ore are described. The integrated circuit comprised pressure oxidation, residue washing, and gold recovery from the washed residue by carbon in leach or carbon in pulp cyanide leaching. Significant factors affecting gold recovery included temperature and retention time in the pressure oxidation step, and the concentration of soluble chloride in the feed. Gold extraction from well washed ore, after oxidation at 210°C for 66 minutes in the autoclave, was typically between 94 and 96%, compared with less than 30% by direct cyanidation.

Jan 1, 1993

By D. G. Chedgy

Environmental improvement efforts are focusing with increasing intensity on pollutants resulting from combustion. The high cost of removing these pollutants at the power station is well documented. Physical coal cleaning has always been and should remain the most economic method of reducing sulfur oxide emission from coal combustion. It is critical in the selection of preparation plant circuitry to consider capital and operating costs, as well as the level of sulfur reduction. This paper describes the technical criteria which must be used for efficient process selection and summarizes the cleaning systems available or in development.

Jan 1, 1990

By R. Benito, J. Lopez, H. Gamarra

This article describes three practical applications of the Hill of Value (HoV) methodology within different stages of strategic planning for open-pit mining operations and projects. In the pursuit of optimal mine planning, this study establishes a comprehensive case study during the (i)design phase, by refining key parameters for efficient decisionmaking. (ii)production planning, where the HoV is used to define achievable production rates, enhancing operational effectiveness through a nuanced consideration of mining and processing capacities. (iii)Additionally, the study introduces a conceptual framework for orchestrating the optimal sequence of multiple pits during the planning phase, with a focus on maximizing project value.

Feb 1, 2024

By J. E. Murphy, L. A. Walters, F. H. Nehl, G. B. Atkinson

The US Bureau of Mines investigated the selective electrowinning of Ag and Au from cyanide solutions contaminated with Cu with the goal of decreasing the amount of Cu codeposited. Decreasing Cu codeposited will reduce refinery costs. Direct current was applied to the cell in pulsed and square wave voltages at 0.7 A h/150 mL of solution. Times tested for each cycle ranged from 1 to 10,000 msecs. Graphite, lead and stainless steel were evaluated as electrode materials. Square wave electrowinning at 70°C (158° F) gave the best separation of Ag and Au from Cu. Applying 2.5 V during the duty cycle, 0.0 V the rest of the period, a duty cycle of 10% to 30%, and a period of 100 msecs to 1000 msecs gave the following results: Ag concentrations decreased from 34 µg/mL to 0.1 µg/mL. Au concentrations decreased from 54 µg/mL to 0.2 µg/mL and Cu concentrations remained almost constant at 560 µg/mL.

Jan 1, 1995

By I. Meliadis

This study presents the methodology and proposals for the restoration of an abandoned quarry in the Greek island of Milos. The local data (soil, vegetation etc.) of the island were collected, analysed and compiled into thematic maps using Geographical Information Systems. The restoration plan was based on the G.I.S. database and suggested the revegetation of the disturbed lands with herbaceous (grasses and legumes) or woody (shrubs and trees) plants. Plants should be indigenous or from other areas with the same vegetation type. Herbaceous plants establish and grow easily protecting the soil from surface erosion. The revegetation success depends on the seed quality, planting season and methods as well as local environmental conditions. Our proposals aim to restore the abandoned quarry with methods that follow the natural succession of vegetation, have minimal environmental impact, low cost and the expected result will be similar to the surrounding undisturbed land.

Jan 1, 2002

By N. S. Dalal, Xianglin Shi

Metal ions, such as chromium (Cr) and vanadium (V) are found as trace impurities in mineral dust. Since metal ion mediated free radical generation has been implicated in many disease processes, we carried out a detailed investigation of the metabolism of these metal ions by biological redox systems and the possible oxygenated radical generation therefrom. We found that highly reactive Cr(5+) species are generated in the reduction of Cr(6+) by NADPH-dependent glutathione reductase, lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase. The reduced metal ion species react with hydrogen peroxide, to generate hydroxyl (•OH) radicals in a continuous cycle. The enzymatic catalysis processes also involves the reduction of molecular oxygen to the superoxide [(0-1 2)] radical. Thus only a trace amount of metal ions chemisorbed on mineral dusts, such as quartz, can catalyze the generation of the highly toxic oxygenated radical species from cellular hydrogen peroxide, suggesting a new biochemical mechanism for mineral dust induced chronic lung injury.

Jan 1, 1991

By Paul R. Thomas

This paper addresses two issues affecting the international ferrochromium market as they pertain to the changing pattern of U. S. chromium import dependency. These issues are 1) the long-term ferrochromium production cost differential between the United States and the Republic of South Africa and 2) the ability of Zimbabwe to expand ferrochromium production and exportation. This paper draws upon the data and analyses of a recent Bureau of Mines Minerals availability Program appraisal that evaluated the international availability of chromium in the form of chromite and ferrochromium from 10 market economy countries. South African ferrochromium producers are shown to have a long-term production cost advantage over U.S. producers of $0.03 to $0.04 per pound of contained chromium, in 1981 dollars. Zimbabwean ferrochromium production and exportation are expected to increase in the future. Major expansions of production capacity will be dependent upon alleviating potentially serious constraints in electric power, rail, and port facilities. In the long term, ferrochromium production costs in Zimbabwe are expected to increase faster than the rate of inflation, because as chromite mining from the podiform resources in Zimbabwe decreases, production from the Great Dyke resources will increase.

Jan 1, 1984

By Steven Atkin, Rens Verburg, Bryony Hansen, David McWharter

The use of paste tailings as underground backfill and for surface disposal is rapidly expanding, and with it comes the requirement to understand and predict its long-term environmental stability. This paper presents the results from a kinetic testing study performed on cemented tailings paste mixtures under both subaqueous and subaerial conditions. In addition, the effects of grainsize reduction are investigated. It will be demonstrated that the long-term weathering behavior of tailings paste is controlled by its physical and chemical characteristics, as well as its placement conditions. The testing indicates that subaqueous disposal of paste inhibits acid generation, whereas the exposed samples produced acidic leachate despite the presence of cement added to meet geotechnical requirements.

Jan 1, 2000

By F. F. Aplan, T. H. Wentzler

Limestone is potentially a low cost material for the neutralization of acid mine drainage and other acidic waters such as steel pickling liquor. Unfortunately, when limestone is reacted wit9 these waters containing large amounts of Fe , Fe+3, and SO4-2 , a coating of gypsum and iron hydroxides form on the surface of the limestone inhibiting further neutralization reactions. The nature of these coatings, their morphology, composition and thickness were evaluated using the scanning electron microscope and microprobe, and the kinetics of limestone dissolution was studied both in the presence and in the absence of the reaction-inhibiting coatings. These data were then correlated with the solution chemistry.

Jan 1, 1992

By J. B. Hiskey

INTRODUCTION The extraction of gold and silver from ores, concentrates, and various metallurgical products can be achieved by a number of hydrometallurgical techniques. The solvation properties of alkali cyanide solutions on gold and silver were recognized 200 years ago. A cyanidation process for leaching gold from its ore was patented in 1887 and 1889 by MacArthur and Forrest. The solvent action of thiosulfate on gold and silver was observed over 100 years ago. Recently, several patents have been issued for processes using ammonium thiosulfate as lixiviant for precious metals, Berezowsky, et. al (1978) and Kerley (1981). Tozawa and and coworkers also examined the dissolution of gold in ammoniacal thiosulfate solution. Thiourea leaching of gold and silver initially discussed by Plaksin and Kozhukhova in 1941 but has received only limited attention since that early work. Use of thiourea as an alternative to cyanide was the topic of several papers presented at the 1981 AIME annual meeting In Chicago, Illinois. Hiskey provided a review of the fundamental chemistry of the dissolution of gold and silver in acidic thiourea solutions. Pyper and Hendrix reported on the leaching of a finely disseminated gold ore using thiourea as a lixiviant. The review article(6) previously presented was fairly comprehensive covering Important contributions to the chemistry of thiourea and the processing of gold and silver with acidic thiourea solutions. A search of the technical literature was made to determine recent (since 1981) progress and developments in applying thiourea to the processing of gold and silver. This review reveals that Soviet and Eastern European scientists are continuing to make major contributions to our understanding of thiourea/precious metal systems.

Jan 1, 1984

By Bruce B. Hanshaw

The Tertiary carbonate aquifer of central Florida is composed of about 2/3 calcite and 1/3 dolomite with minor amounts of quartz and apatite. The Mg content of the calcite is lower in the recharge areas than in the deeper confined parts of the aquifer system. Various geochemical lines of evidence indicate that much of the dolomite is of penecontemporaneous origin but that some may have been formed much later, possibly by ground water. Theoretical studies indicate that the Mg/Ca ratio in solutions is about unity for the three-phase equilibrium, calcite-dolomite-water. Solutions, such as ocean water and some subsurface brines, have Mg/Ca ratios higher than one and should represent dolomitizing solutions. In the areas of principal recharge to the Floridan aquifer, ground water is undersaturated with respect to both calcite and dolomite, and the Mg/Ca ratiois as low as 0.05. As the water moves downgradient, the Mg/Ca ratio systematically increases and approaches unity; saturation of the solution with respect to both calcite and dolomite also increases with length of travel in the system. Thus, in the zone of active potable-water circulation, the chemical process is one of dissolution of minerals until saturation is reached or exceeded. However, in the deeper brackish-water zones that underlie peninsular Florida, dolomite may be forming where the Mg/Ca ratio is greater than one. The necessary Mg may be derived from ocean water or brines recycled through the system as the hydrologic regimen is changed. The driving force may be simple mixing, relative fluctuations of sea level, or a combination of mechanisms.

Jan 1, 1972

By Elżbieta Węglińska, Andrzej Leśniak

The earthquake locations are generally scattered mainly due to a simplified velocity model or seismic event picking errors. The aim of our research was to increase the resolution of the cloud of microseismic events recorded during mining activity in the Bobrek hard coal mine on the 3/503 coalface to delineate seismically active structures using unsupervised machine learning algorithms. We presented results of applying two completely different algorithms for reducing scatter in microseismic location to all events recorded during mining activity on the coalface - the collapsing (proposed by Jones and Stewart in 1997) and condensation (proposed by Kamer in 2015). The collapsing method simplifies the seismic cloud by shifting events inside their error ellipsoids towards local source densities. The error ellipsoids are determined by errors in the measured parameters and seismic network configuration. The advantage of the collapsing method is the partial elimination of blurring of the microseismic cloud. The condensation method reduces the size of the set of seismic events without changing the geometrical information. The reduction of the number of seismic events in the catalog takes place through the condensation of localized events with larger uncertainty into events with lower uncertainty. The spatio-temporal analysis of microseismic events was performed separately on two processed clouds – collapsed and condensed one. We examined how collapsing and condensation methods affect the automatic detection of clusters of microseismicity using density-based spatial clustering of application with noise algorithms. We compared structures detected by the machine learning algorithms in both seismic clouds first created by collapsing and second by the condensation. We identified structures created by mining activity and structures related to the local tectonics activated by mining. The presented results are essential for the prediction of future tremors induced by the mining operation and tectonics and thus ensuring safety in the mine.

Apr 26, 2022

By Pascal Deschamps

"INTRODUCTION During the last decades, many underground facilities for the storage of hydrocarbons have been excavated worldwide and the technology is fully mature. Similarly to other underground structures, the initial basic design has to be adapted along with the work progress, in order to cope with the actual site conditions and in particular the geology, hydrogeology and associated rockmass quality. In addition, Client’s or underground Contractor’s constraints (such as resources availability, schedule or cost impact) may vary from design to construction and require last minute adjustments. Engineers are required to introduce flexibility and anticipation of unexpected situations (similar to the above-mentioned) while conceiving large underground facilities. Although most of the cases require only minor adaptations, crucial parts of the facility have sometimes to be considerably modified and reviewed. This article will present four cases evidencing how the design of one of these essential structures - the concrete plug – has been adjusted during site implementation without impairing the initial performances. Hydrodynamic containment The product containment of the unlined caverns discussed here is ensured by the principle of hydrodynamic containment. A permanent water flow is naturally or artificially maintained with an orientation toward the storage cavern and then, neither product-tight membrane nor lining are required. The hydraulic gradient (and the associated water flow lines), being directed from the surrounding mass toward the cavern, prevent from outward migration of the product. If the hydraulic gradient is not sufficient or if the water table is evidencing instability, water can be artificially injected into the rockmass through purpose-built boreholes, drilled from dedicated galleries. This water injection system, called the water curtain, is generally located several tens of meters above the level of the cavern. This principle is illustrated here after."

Jan 1, 2016

By H. Douglas Dahl

Thank you, Don Gentry, for your generous introduction. It is not adequate simply to say that I appreciate very much the vote of the Award Committee putting forth my name as the winner of the 1992 Daniel C. Jackling Award. To look at the list of previous Jackling Award winners is a humbling experience. The Society for Mining, Metallurgy, and Exploration has been blessed with some exceptional members over the years, and I feel privileged indeed to be included among the Jackling Award winners. During the years of my education at Penn State, my field of specialization was mining engineering, with particular emphasis in my master's and Ph.D. work on rock mechanics. But my career has not been quite so tightly focused as that. I have been involved with coal mining in all its variety - its technical aspects, both theory and practice; and its business side, dealing with management and labor, accountants and lawyers, politicians and environmentalists. And I have also been involved with related fields - construction; exploration; barges, railroads, ships and docks; supply houses; the coke business; you name it. Coming from that practical background, I believe it is most appropriate that I talk with you today about some practical matters. But I will not advise you today how to mine coal or protect roof in a hard-rock mine. You fellows know how to do that. The practical matters that I have in mind relate to policy - national policy. I will acknowledge immediately that national policy is often much less than practical, but bear with me as we explore the subject together. I am reminded of a supervisor I had early in my career. He very strongly advised me, back in 1961, to "get involved in the political process," for without objectivity injected into our national policy making, we will become a second-rate economic power. I have selected as the subject of my remarks today, "Coal and the de facto National Energy Policy." There is an energy policy relating to coal, a de facto one, and it's the one we see as a result of regulation, attitudes and culture from our nation's capital. This de facto policy is the one we in the coal business live with every business day. My thesis is very simple - Coal is, in fact, a vital part of our national energy policy and will remain so, as a practical matter, no matter what politicians may do to us, or not do to us. Coal will prevail - that will be the happy ending to my story in which, of course, we are the good guys in the black hard hats. But first, I must flesh out the plot with some other characters and with some threatening activities. There are five main characters in my story: in order of appearance - Perpetual Politics, Rampant Regulation, Selective Science, Electrification and Confident Coal. The time: the present. Perpetual Politics is always a threat to coal. When you cross the Capital Beltway into Washington, D.C., check your wallet and your gold fillings, because you're not likely to run into any friends. On Feb. 20, 1991, just over one year ago, President Bush presented to Congress his National Energy Strategy. It's a thick document of more than 260 pages, with discussions on securing our future energy supplies, increasing energy effi-

Jan 1, 1993

By L. P. Johnson

Longwall mining has gained acceptance as a safe method of maintaining coal production where conventional systems were unsuccessful or uneconomic due to bad roof conditions (Kuti8). One of the major problems confronting American operators involves the correct choice of equipment which should be selected to suit the local mining and geologic conditions for optimum productivity. To achieve this, factors such as rock strengths, local geology, panel geometry, and panel orientation must be examined to optimize production and minimize down time due to ground control problems. Little quantitative information is available in the literature regarding the effects of geologic conditions on American longwall operations, and past implementations of longwall systems appear to have been based largely on experience. When mining engineers are able to assess the geologic conditions both quantitatively and qualitatively, they can more fully optimize equipment selection and panel design.

Jan 1, 1977

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 W. J. Dolinar, S. P. Sandoval

The US Bureau of Mines (USBM) implemented the Fe2+/ Fe3+-SO2 anode reaction in a Cu-electrowinning cell with full-size electrodes. Electrowinning was conducted using industrial electrolyte at 258 A/ m2 (24 A/ft2) and 40°C. Manifold injection of electrolyte provided circulation between the electrodes. Five-day operation using an optimized manifold gave an average cell voltage of 0.94 V at 89% current efficiency, which amounted to an energy savings of 2.82 MJ/kg (0.355 kW-hr/lb), compared to conventional electrowinning. Acid milling 5was completely eliminated, and the SO2 concentration 23 cm (9 in.) above the cell averaged 0.06 ppm.

Jan 1, 1996

By F. M. Benavides

The mining complex being analyzed consists of four mines and two processing plants located in an area where there are several existing modes of transportation. Figure 1 shows a map of the general layout of the four proposed mines and the two existing processing plants. The mines are identified by the numerals "I" through "IV" and the plants by the letters "A" and "B". A proposed overland conveyor would collect the product from all four mines and convey it to Processing Plant A. Alternate transportation systems are as follows: Railroad transport from Mines I and II to Plant B; Highway trucking from Mines I and II to Plant A; Off-the-road truck haulage from Mine III to Plant B and from Mine IV to Plant A. River transportation from the mines to the processing plants was not considered in this study under the assumption that the high capital investments for the loading and unloading facilities, in addition to difficult traffic problems, would make this mode of transportation unattractive.

Jan 1, 1980

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 Mark J. Logsdon, Barbara Basse

Mississippi Valley Type Pb-Zn deposits are widespread in the midcontinent U.S. and have been mined from the 1800's to present. Some tens of thousands of acres of mined land in the Tri-State District have been designated as Superfund sites as a result of surficial mine wastes and ground waters with elevated levels of metals. EPA considers the surficial mine wastes to be hazardous and a major source of acid mine drainage fAMD) that degrades water resources and threatens human health and the environment. To mitigate potential risks at one site near Galena, Kansas, a group of mining companies who had been identified by EPA as Potentially Responsible Parties IPRPs) proposed subgrade disposal of the mining wastes in shafts and subsidence features. However, this proposal was challenged by the Agency on grounds related to AMD and the potential for degradation of ground water quality. The PRP team developed a program of materials characterization, laboratory-scale leaching, and finally large-scale, pilot testing in the field. Static and dynamic leaching tests at both laboratory scale fusing artificial rainwater under both variably and fully saturated conditions) and field scale (using pH 4.5 ground water) showed that the surficial wastes do not produce acidic leachate and are not a long-term source of metals. Laboratory chemical and mineralogical tests show that the mine wastes contain substantial carbonate, but very limited iron sulfides, consistent with the leach test results. EPA "characterization" tests fEP Toxicity and TCLP) compare very poorly with tests simulating the expected leaching conditions. While these tests would classify the surficia1 wastes as "hazardous, they do not characterize the behavior of the high-volume, low-concentration, coarse-grained materials with respect to environments and disposal options of interest. To be meaningful, characterization of mining wastes must be performed in a manner that simulates the environmental conditions that are actually of interest with respect to a specific decision, such as subgrade disposal in the saturated zone.

Jan 1, 1991