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By Jörg Holzhäuser, Matthew Crow

An 18.5 km (12 mile) long tunnel is being driven by four Earth Pressure Balance Tunnel Boring Machines (EPB-TBMs) of 4.7 m (15.5 ft.) diameter through alluvial sand, gravel, silt and clay above and below the groundwater table in Los Angeles beneath buildings, railroads, freeways and the L.A. River. Continuous automatic data recording of TBM operation and field inspectors' records, accompanied by monitoring of 5,000 surface reference points and 268 borehole extensometers were used to obtain information. The paper explains the reason for selecting the method of EPB-tunneling to ensure stability of the tunnel and meeting of environmental requirements, and presents data collected to monitor and demonstrate the performance of the TBM sin the different ground conditions encountered.

Jan 1, 2003

By P. R. Bailey

The use of carbon for the recovery of the gold dissolved in cyanide leaching began with a pilot unit at Barberton in 1977. This was quickly followed by larger scale plants at Modderfontein (1978), President Brand (calcine 1980), Western Areas (filter tails 1980) and Beisa (primary ore 1981) and has grown to become the preferred process. There are currently 34 operations that use the carbon in pulp/leach process which accounts for 35 percent of South Africa's gold production. The size of individual plant varies over a wide range.

Jan 1, 1993

By Richard E. Gray

Virtually all structures show some signs of distress due to deterioration of the building components, to changed loads, or to changed support conditions. Changed support conditions result from ground movements. In mining regions many cases of structural distress are attributed to mining without considering alternative causes. This is particularly true of coal mining since it occurs under extensive areas. Coal mining is estimated to have already undermined more than eight million acres and may eventually undermine 40 million acres in the United States (HRB Singer, Inc., 1977). Other nonmetal and metal underground mines impact much smaller areas. Although it is sometimes difficult, even with careful study, to identify the actual cause of damage, persons responsible for underground coal mining should at least be aware of possible causes of building stress other than mine subsidence. This paper presents information on distress to structures and briefly reviews a number of causes of ground movements other than subsidence: Mass movements, dissolution, erosion, frost action, shrinking and swelling, yield into excavations and compressibility

Jan 1, 1986

By Rodrigo Peroni, Vitor Campos

Carajás is one of the largest open pit mines in the world. The mine is comprised by a haul road network more than 100 km long, where the need for good roads is paramount and determining of the truck performances. This work integrates, regarding the ultimate pit design, an approach to consider an economic value to an originally unfit material, assuming it has the appropriate characteristics for haul road construction, which sometimes lies over economic iron ore. This measure demonstrated an improvement in the utilization of resources and guarantee the necessary material to the haul road design and Mining Pads maintenance.

Jun 25, 2023

By M. J. Virnig, G. A. Kordosky

Throughout time, the mining industry has been very successful in meeting the world's requirements for metals and materials while meeting the challenges of decreasing ore grades and increased emphasis on protection of the environment. This success has been due to the development and implementation of new technologies. A clear example of such a development over the past 25 years is the increasing use of leaching/solvent extraction/electrowinning for the recovery of copper from oxide and sulfide ores. The key to the successful introduction of this technology was the discovery and development of the hydroxyoxime liquid ion exchange reagents by General Mills Chemicals (now Henkel Corporation). An important role was also played by the close working relationships between General Mills Chemicals and Ranchers Exploration which resulted in startup of the first plant in 1968 and between General Mills Chemicals and Bagdad Copper which resulted in the startup of the second copper SX-EW plant in August of 1970. Following on the heels of the hydroxyoxime development came the commercialization of other new chelating reagents based on different chemical functionalities, i.e., beta-diketones, alkylated 8- hydroxyquinolines and sulfonamidoquinolines. This initial spurt of activity was then followed by a slowing of development in terms of new reagent functionalities. Activity has continued in terms of further optimization/improvement of existing reagent functionalities but the commercialization of new reagent functionalities has slackened. This observation reflects the fact that the development of new reagent functionalities for metal recovery has become increasingly more expensive such that the right combination of price and sales volume must exist in order to justify the investment required to bring a new reagent to the market place. Given the dependence of the mining industry on innovation to meet the needs of the future, one can ask how these new developments, particularly in new reagents, will occur. To arrive at an estimate of the costs involved in commercializing a new metal extractant functionality, particularly a chelating type functionality, a case study of the development of LIX ®* 34

Jan 1, 1994

By P. Karimi, A. Akcil, A. Amini, H. Abdollahi

"In this study, cyanidation experiments were carried out on a massive sulfide ore sample, whose grades of the precious metals gold and silver were found to be 4.2 g/t and 311.9 g/t, respectively. Other elements in the ore were arsenic with average grade of 1,751.6 g/t; antimony, 619.7 g/t; zinc, 781.4 g/t; copper, 454.6 g/t; lead, 101.8 g/t; mercury, 324.3 g/t; and bismuth, 0.6 g/t. The first objective of test work focused on determining the best conditions for extracting gold from the ore, ground to less than 75 microns. Different influential parameters such as particle size fraction, cyanide concentration, pH and leaching time were investigated. The optimum parameters were found to be particle size fraction of less than 25 microns, cyanide concentration of 2,000 mg/L, pH of 11 and cyanidation time of 24 hours. In these optimum conditions, the highest gold and silver leaching efficiencies were 76.88 and 59.63 percent, respectively. In addition, roasting as pretreatment at a temperature of 700°C over a period of two hours was evaluated. Cyanidation testing of the roasted ore in the optimum conditions found increases in the gold and silver leaching efficiencies to 85.97 and 67.57 percent, respectively. Moreover, antimony extraction rose to 43.10 percent, from 23.73 percent without roasting.IntroductionGenerally, gold ores can be classified as “free milling” or “refractory,” depending on how they respond to cyanide leaching (La Brooy et al., 1994; Celep et al., 2009). While high gold recoveries (> 90 percent) from free-milling gold ores can be readily achieved, refractory gold ores are often characterized by low gold recoveries (50-80 percent) within a conventional cyanide leaching process (Rubisov et al., 1996; Adams, 2005; Celep et al., 2009). The presence of preg-robber components such as carbonaceous matter, sulfide minerals and aluminosilicate can further decrease gold and silver dissolution rates and recoveries. With the negative effect of the presence of preg-robbers, gold dissolution is considerably diminished in solutions with high cyanide concentration (Tan et al., 2005). In such refractory gold ores, gold particles may sometimes be occluded or included in the sulfide minerals, and pretreatment becomes necessary to break down the mineral structure to liberate gold for subsequent recovery. These ores are usually pretreated with an oxidizing process, after which gold and silver can be recovered by a standard cyanidation process. The main oxidizing processes available for refractory gold ores are roasting (LaBrooy et al., 1994; Angelidis and Kydros, 1995; Li et al., 2009; Karimi et al., 2010; Kyle et al., 2012), biological oxidation (Lawrence and Bruynesteyn, 1983; Komnitsas and Pooley, 1990, 1991; Deng and Liao, 2002; Ciftci and Akcil, 2010, 2013) and pressure oxidation (Mason, 1990; Murthy et al., 1992; Qingcui et al., 2009). In addition, ultra-fine grinding is being used in some plants for the liberation of gold and silver particles that are interlocked in the sulfide or silicate minerals (Celep et al., 2011)"

Jan 1, 2015

By L. R. McCullough

To compete in Today's Market, Mine Managers have two, often conflicting tasks. They are to improve productivity, allowing the mines to compete in our world markets and to improve the environment in which our miners must work. To Maintain and improve the environment to ever increasing acceptable levels requires monitoring. In years passed this required considerable labor, which was provided by the Ventilation Department. They continuously took manual samples using hand-held instruments, sampling gas level such as CO for fire and methane for explosive risks. In addition they took continuous air velocity readings with hand-held instruments which allow them to calculate the ventilation air movement in each area of the Mine. This manual gathering of information was not only expensive and slow but marginal at best. It was marginal because the gas sampling was sporadic rather than continuous, as sample reading taken in one part of the mine would likely not be repeated for another 8 hours. If problems did occur, they likely went unobserved until they reached crisis proportion.

Jan 1, 1990

By Bryson D. Trexler

Slope stability in open pit mines is governed by rock structure, rock quality, ground water conditions, blasting, pit geometry and excavation method. Of these factors, the control of ground water pressures often represents the primary tool to improve slope stability. Production equipment has recently been used to stabilize two slide areas by dewatering using blasthole drills for vertical holes and secondary drills for horizontal holes. This paper describes both of these dewatering programs and contrasts an earlier slope stabilization program that employed a subcontracted horizontal drill.

Jan 1, 1983

By G. R. Burman

Gilsonite is a brittle, natural solid bituminous resin, classified as an asphaltite. It is found in near-vertical veins in the Uintah Basin of Eastern Utah. Discovered well over 100 years ago by Samuel Gilson, this unique material has, since its finding, enjoyed a variety of commercial and industrial applications. Early uses for the product included black automotive paint and beer vat linings. Among its many important uses today are additives for oil well drilling fluids and cements, additives for sand castings for the foundry industry, reinforcing agent for asphalt pavements, and dispersing agent for black inks. Gilsonite is mined and processed in Bonanza, Utah, by two companies, American Gilsonite Company (AGC), an operating division of Chevron Resources, and Ziegler Chemical, a privately held company headquartered in New York.

Jan 1, 1990

By Stanley W. Ivosevic

The South-Central area of the Osa Peninsula, Puntarenas Province, on the Pacific coast of southern Costa Rica, may have produced on the order of 30,000 kg (100,000 troy oz) of gold since prehistoric times. The Peninsula lies along an 800- to 900-km-long belt of late Mesozoic eugeosynclinal rock deposition, hydrothermal activity, and deformation (Campanian). The oldest rocks exposed in the area are basalt and tuffaceous mudstone of the Late Jurassic or Cretaceous Nicoya ophiolite complex. The Nicoya Complex is overlain by weakly lithified Pleistocene Older Sediments, predominantly conglomeratic sandstone and derived from erosion of the Nicoya Complex. Erosion reduced the Complex to a surface of high relief, so that the detrital source was in the area originally; the source retreated with subsidence. Stratigraphically, the Older Sediments are followed by surficial deposits of intermediate age, consolidated Younger Sediments reworked from Older Sediments, and unconsolidated Holocene surficial deposits reworked from Younger Sediments. The most prominent structures are a northeast-trending anticline and northeast and northwest fault sets. Some deformation was Cretaceous, but folding and much faulting occurred after deposition of the Older Sediments. Remnants of plainlike features and destructional terraces on the Older Sediments attest to stepwise downcutting of the terrain during successive stages of uplift. Near the end of this process, the present valley floors and coastal headlands developed. During a probable epeirogenic rise in sea level, Younger Sediments filled the valley bottoms and an aggradational coastal plain developed. Sea level dropped by stages and with some reversals to its present position; this caused stepwise incision of the valley fill, stepwise beveling of the coastal plain, and development of the present wave-cut platform. Spilitization around the time of the Campanian orogeny caused some parts of the Nicoya complex to be calcitized and others to be silicified. Gold, pyrite, and probably additional silica were introduced during subsequent hydrothermal activity. Native gold was eroded from Nicoya Complex lodes and reconcentrated through three generations of placer gold deposits. First, the gold was deposited as a detrital.

Jan 1, 1977

Grinding and energy input in stirred media mills are studied as functions of grinding time, stirring speed, media size and density, solid concentration, impeller and tank dimensions and design, and other relevant variables. Ground product size and surface area are determined with respect to the above variables. Changes in energy input and media/pulp rheological properties during grinding are described. The best conditions for grinding limestone in the laboratory stirred media mills have been identified. Equations for correlations involving power and modified Reynolds numbers have been established.

Jan 1, 1995

By R. Rodgers

The Pinto Valley concentrator of BHP Copper Inc. restarted its sulfide mining operations in September 2007 to produce copper and molybdenum concentrates. During the plant production ramp up, the copper/molybdenum circuit quickly reached the copper grade and recovery targets, but the production and quality of the molybdenum concentrate continued to be a challenge. Even though several improvements in the molybdenum circuit were completed, the final molybdenum concentrate did not meet contractual specifications. After reviewing several options to improve grade and reduce contaminants, the installation of three flotation columns were chosen. The column design and construction were done using in-house craftsmen and engineers. Ten days after commissioning, the columns successfully reached a steady operation and began producing molybdenum concentrate to the required specifications, that is, high molybdenum tenors and low copper and iron content. The Pinto Valley operations, are comprised of the Pinto Valley concentrator, the Pinto Valley dump leaching and a solvent extraction/electrowinning (SX/EW) plant. The concentrator operated from 1972 to 1998 when mining and milling operations were curtailed for economic reasons. The SX/EW plant continued operations for copper cathode production. After a cessation of mining operations of almost 10 years, Pinto Valley operations began a restart project in January 2007, to bring the mine and the concentrator back into production. Copper concentrate production started in October 2007 after refurbishing and upgrading the facilities with a new DCS system and filter plant. The daily targets of the concentrator were to treat 56.7 kt (62,500 st) of ore, produce 762 t (840 st) of copper concentrate containing 27.5 percent copper at recoveries of 86 percent and produce 2.2 t (2.5 st) of molybdenum concentrate containing more than 80 percent MoS2.

Jan 1, 2010

By W. B. Greer

The performance of seals in boreholes, shafts, and tunnels is an important concern in mine safety, in the control of effluents from operating and abandoned mines, and in the underground containment of hazardous wastes (Einarson and Abel, 1990; Mining Waste Study, 1988). Despite the clear need for effective seals, few documented test results are available concerning the performance of in-situ seals. Some evidence indicates that horizontal or near-horizontal holes are especially difficult to seal properly (Kelsall and others, 1982). This research involved the installation, extensive hydraulic testing, removal, and post-test examination of a l0-cm-long by 10-cm-diameter cement grout seal in a near-horizontal borehole in limestone. The work was performed in an underground mine on Marble peak in the Santa Catalina Mountains, Arizona. A test hole was diamond cored in the re-crystallized limestone of the Escabrosa formation. The hole is 33.24 m long, 10 cm in diameter, and dips at 10.4 degrees. The hole extends between two drifts and thus is accessible from both ends.

Jan 1, 1992

By D. R. Willmer, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT This study analyzed the publicly available health and safety policies of 26 mining companies to determine the quantity of health and safety (H&S) practices that mining companies encourage in relation to the Plan-Do-Check-Act cycle. A thematic content analysis of the policies identified elements and practices within the text. On average, companies communicated information on about 7 elements (range 1–14, standard deviation = 3.49) and discussed 15 practices (range 2–34, standard deviation = 9.13). The elements in which companies highlighted the most practices were risk management, emergency management, leadership development, and occupational health. A discussion of the policy trends shows areas that mine sites can improve upon within their Plan-Do-Check-Act cycle, in addition to encouraging the use of both leading and lagging indicators to manage health and safety performance. INTRODUCTION Mining companies and their employees are expected to identify and manage risks at their worksites to ensure the health and safety (H&S) of everyone at the site. The primary mechanism in place to control these risks is a company’s health and safety management system (HSMS) (Boyle, 2012). Broadly, an HSMS is a set of standard, interrelated, and interacting elements used to promote and achieve occupational H&S goals (ANSI/AIHA Z-10, 2012; BS OHSAS 18001, 2007). The practices conveyed within an HSMS are expected to minimize incidents, injuries, illnesses, and even save worker lives (Alsop and LeCouteur, 1999; Arocena and Núñez, 2010). In the United States, both the Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration (MSHA) regulate and encourage aspects of an HSMS (US Federal Register, 2011, 2010). Many HSMS documents (i.e., Chemical Industries Association, 1995; Health and Safety Executive [HSE], 1995; International Labour Office [ILO], 2001) attribute the source of their basic management system to Deming’s Plan-Do-Check-Act (PDCA) model of continuous quality improvement and organize their practices within this cycle (Johnson, 2002). The PDCA cycle is a well-adopted approach in health and safety management and promotes continuous learning and adaptability (Robson et al., 2007)."

Jan 1, 2018

By Ehsan Moosavi, Kamyar Tolouei, Mehran Gholinejad

The literature defines rockbursts in slightly different ways based on their generation mechanisms, field phenomena, and degree of damage, but in a way that is almost consistent. Generally, a rockburst refers to seismic events that mainly happen in underground excavations, for purposes such as underground mining, road and railway tunnels, nuclear power, etc., and that are followed by the collapse and outburst of rocks. Long-term rockburst prediction can be abstracted as a classification problem mathematically, in which we can introduce deep learning to solve it. Further, using deep learning in rockburst prediction can overcome drawbacks such as subjectivity and inconsistency brought from previous traditional approaches. A rockburst data-set, was employed to evaluate the current method for predicting rockburst grade, and the good results of overall success rate were obtained. The results indicated that the proposed algorithms can speed up parameter optimization search, the proposed method is robust model and might hold a high potential to become a useful tool in rockburst prediction research.

Apr 26, 2022

By Jr. Schnakenberg

In 1986 the U. S. Bureau of Mines (USBM) embarked on a major research effort to develop technology that can substantially reduce worker exposure to face hazards simply by relocating the equipment operators to an area of relative safety. This reduced exposure mining system (REMS) research effort enhances the USBM ongoing health and safety research efforts to reduce and control dust and noise and to reduce accidents through training and better mining practices. This paper reports progress of the research that is developing and will demonstrate the technologies required for the computer-assisted tele-remote operation of continuous mining machines, haulage systems, and roof bolting machines.

Jan 1, 1996

By Peter Cammack

Where raw coal from a mine is treated in dense medium separators ash in the washed product is generally very consistent, provided control of the medium suspension is maintained at a given specific gravity. When, however, the washing process is a Baum jig or other similar apparatus, making a separation at rather arbitrary gravities, the control of the product ash is less accurate, particularly in those cases where the design capacity of the washbox is exceeded by the load of high ash fines. In either of these cases an instantaneous measurement of ash while not essential would be desirable, to check the quality of the washed product and provide operator or management with instantaneous warning of changes in ash. Nearly 60% of all British coal mined goes for electricity generation, to burn at 17% ash, and since the overall average ash content of raw coal as mined is about 30% and varies within a range of 18 ? 40%, incombustible material has to be removed. The ash specification could be met either by total washing, or by washing part and blending the clean coal produced with the remaining untreated coal. Some plants use a straight tonnage split, but generally speaking in Britain it has been found more economical to screen and wash the oversize only. In either case for effective quality control in blending an instantaneous determination of the ash content of the product as it is made has been found essential, since standard ash determination by pyrolysis methods is lengthy and provides information too late to be used in the control of plants blending at the rate of 1000 ton/h.

Jan 1, 1976

By O. M. Johnson

Barite and bentonite are the two principal components of drilling fluid systems used in the petroleum industry for oil and gas well drilling with rotary-type rigs. Approximately 87 percent of the world's annual production of barite is used in drilling applications. Of the worldwide production of bentonite, an estimated 30 percent is used. The drilling fluid, or drilling mud, to which barite and bentonite are added, performs five distinct functions: Lubrication-The liquid phase of the drilling mud lubricates the drill bit, preventing premature failure of the cutting edges and bearings. it also helps to soften the formation being drilled. Cuttings Removal-A mud system must be able to carry rock cuttings broken loose by the bit up to the surface where they can be removed by mechanical or chemical methods. The fluid's ability to perform this function depends upon maintaining a proper balance between the rate of circulation of the fluid and the colloidal properties required to entrain the cuttings in the mud to prevent their settling to the bottom of the hole. Hole Stability-The pressure exerted by the mud against the wall of the bore hole prevents the collapse of the uncased portions of the hole. Downhole Information-The fluid characteristics of the mud should be such that good cuttings samples, cores and electric logs may be obtained to help evaluate a well's productive zones and potential. Control Oil, Gas and Water Flows-It is essential that a drilling fluid offset any pressure from naturally occurring formation fluids in order to prevent a potentially wasteful and dangerous blowout.

Jan 1, 1980

By Bruno Bussière, Michael Aubertin, Robert P. Chapuis

Covers with capillary barrier effects (CCBE) have been used in recent years as gas barriers for the isolation of wastes, including reactive mine tailings. Capillary barrier effects help to maintain a high degree of saturation in the moisture retaining layer, which then reduces gas flux. Various factors affect the degree of saturation of the moisture retaining layer in a CCBE, such as the material water retention characteristics and layer thickness. Slope geometry can also influence the hydrogeological behaviour of a CCBE, but this factor has frequently been ignored in the past. In this paper, the authors show some results of a numerical study that illustrates the influence of slope on the behavior of capillary barriers made of different types of material. The numerical model calculations are based on an actual case of a CCBE constructed in northern Quebec. This investigation shows that the water content profile is greatly affected by the position along the slope. Thus, it is necessary to evaluate the influence of the geometry to properly establish the performance of a cover system.

Jan 1, 2000

By L. Yuan, J. Soles, W. Tang, R. Thomas

Lithium-ion battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12V, 24V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicated that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Feb 1, 2023