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By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

A parametric study was conducted to establish the optimum operating conditions for the column flotation of fine coal. The parameters examined in this investigation included collector and frother dosages, feed solids content, and the volumetric flow rates of feed slurry, air and wash water. Despite the wide range of conditions studied the experimental data were found to fall along single grade-recovery curves, just below the maximum separation predicted by the release analysis technique. The deviation of the parametric test data from the release curve was attributed to the nonselective entrainment of mineral matter associated with poor froth washing. The operating point on the characteristic recovery-grade curve was found to be primarily determined by feed rate and aeration rate.

Jan 1, 1992

By M. S. Celik

Salt-type minerals are usually floated with anionic and cationic collectors. Flotation of a number of systems has been reported to remarkably increase above the concentrations where surface precipitation of collector-metal salt is initiated. Some studies attribute this phenomenon to heterocoagulation of oppositely charged collector colloid and mineral particles. In this study, examples are given on boron minerals to demonstrate that the high flotation region occurs when particles, colloidal precipitates and bubbles acquire a similar charge which induces Van der Waals interactions resulting in hydrophobic bonding.

Jan 1, 1995

By G. Keizer

Cortez Gold Mine (C.G.M.) is located in Lander County, Nevada, approximately 80 miles southwest of Elko, Nevada. It is accessed via Nevada State Highway 306 south from Interstate 80. This operation is a joint venture between Placer Dome U. S. Inc. (60% operator) and Kennecott Corporation (40%). The claims which supply oxide and refractory ore feed to the Cortez milling facility are located in both Lander and Eureka Counties. These include the Cortez and Horse Canyon deposits all operated by C.G.M. Joint Venture. Other deposits outside the C.G.M. claim area include; Fire Creek, Buckhorn, Gold Bar and Tonkin Springs. These deposits all occur along the Battle Mountain/Eureka Trend.

Jan 1, 1993

By J. P. Ducarme, J. L. Carr, C. C. Jobes

"An average of 1.2 fatalities occur per year in underground coal mines in the United States when a miner is struck or pinned by a remote-controlled continuous mining machine. Proximity detection technology provides a means to prevent these types of accidents by disabling all machine motion when a miner is in close proximity. Researchers at the National Institute for Occupational Safety and Health (NIOSH) have developed the intelligent Proximity Detection (iPD) system, which continuously tracks the position of miners near the machine and disables only those machine motions that could cause a pinning accident. This system, previously demonstrated using non-permissible proximity detection hardware, has now been shown to be effective when implemented using an MSHA-approved system as a platform. Performance tests have shown accuracy, repeatability, and stop zone identification to be comparable to or better than the system demonstrated with non-permissible hardware. INTRODUCTION Underground coal mining room-and-pillar operations typically use Continuous Mining Machines (CMMs), such as the one shown in Figure 1. When CMMs first became available, they were operated from an on-board operator’s compartment that protected operators from roof falls and other hazards but severely restricted visibility and subjected them to machine vibration and high levels of dust and noise. To solve these problems, remote controls were developed to operate CMMs. Now CMM operators are free to position themselves for best visibility of each mining task and are no longer subjected to the rough motion of the CMM during mining operations or the dust and noise generated by the machine. However, this technological advance removed operators from the protection afforded by the operator’s compartment and exposed them to the hazard of being struck or pinned by the CMM or other large moving machines."

Jan 1, 2015

By W. M. Colwell

When it comes to the analysis of gold bearing ore, there are literally dozens of variables that contribute to the final "true value" of a given sample. Initial sample selection, splitting size and method, inherent nugget gold, pulverization method, and analytical method variations are but a few. However, it seems that the inherent nugget gold particle is targeted as the primary reason for intra and inter-laboratory variations in assay. The following study will show that this is not always the case. A series of tests were undertaken for the Aurora Partnership-Aurora Project to solve inter-laboratory variations in the analyses of blasthole cuttings. Initial concern was centered on the probability that free gold occurrence was resulting in erratic results for the mine's cyanide shake assays and outside laboratory fire assays. Comparison of fire assay and cyanide shake assay was sporadically consistent with previously demonstrated extraction percentage for the cyanide method. The goal was to delineate the factors that ensure consistency in analyses; implement, where needed, Good Laboratory Practices; and reestablish acceptable analytical method correlation.

Jan 1, 1993

By Shawn P. Coughlin, Michael A. Schimmenti, Juan Leonardo Tello del Pino

"PROJECT OVERVIEWThe Sistema de Potabilización Área Norte project (Northern Area Purification System) was a major expansion of the potable water system in Buenos Aires Province, Argentina. The aim of the project was to transport and purify raw water from the Paraná River to provide potable water for five communities in the northern part of the province, benefitting up to two million inhabitants. The project was constructed by a joint venture of four South American contractors (“the JV”), and consisted of the following key components:• Treatment Plant: A 16 hectare area was cleared for the construction of a treatment plant to purify 900,000 m3/day of raw water from the Paraná River and distribute it to the surrounding communities.• Bored Tunnel: Nearly 15 km of 3.6 m inner diameter tunnel, ranging from 18 to 22 m below grade, was bored with two EPB tunnel boring machines to draw the raw water from the river. The TBMs started from a central launch shaft and proceeded in opposite directions: Cristina advanced northbound to the Paraná River Intake System, and Liliana advanced southbound to the new treatment plant.• Access & Ventilation Shafts: Five access shafts and eight ventilation shafts were installed along the length of the tunnel. The access shafts were designed to provide entry points for inspection and maintenance of the final tunnel. The five shafts consisted of: one central launch shaft in the middle of the tunnel alignment, one retrieval shaft at each end of the tunnel (Intake and Treatment Plant, respectively), and two intermediate shafts. The intermediate shafts were installed before the TBM passed, with a final liner to be installed afterwards. Access Shaft 3, the intermediate shaft located between the launch shaft and the treatment plant, experienced persistent leaks during initial excavation attempts."

Jan 1, 2016

By Corale L. Brierley

Bacteria, algae and fungi react to heavy metals in their environment by immobilizing, mobilizing and/or transforming metals. Microorganisms carry out these changes by (1) precipitating metals outside of the microbial cell, (2) binding and complexing metals to the outside of the microbial cell's protective coating, (3) accumulating metals inside of the microbial cell, or (4) transforming metals by oxidation, reduction, methylation or demethylation. Most of these mechanisms are operative in constructed aerobic and anaerobic wetlands for metal's remediation. Several more advanced biotechnologies for metal's removal from aqueous streams have been introduced, but have not been widely accepted commercially.

Jan 1, 1995

By M. Guzman, S. B. Thais, M. F. Obispo, M. R. Arribasplata

The impact generated by old abandoned mines in Peru have produced mining environmental liabilities, which can generate an impact on the environment. In the search for long-term sustainable solutions, Phytoremediation is presented as an interesting alternative, since it allows the use of Peruvian native plant species for the accumulation of heavy metals. In this paper, we present the results of native high Andean species: Stipa Ichu and Cortaderia Nitida. The final metal concentration in the aerial parts and in the roots of each plant show that Stipa Ichu is more efficient to recover Fe, reaching almost 278 times its initial value. In the same way, this plant is efficient to remove Zn, Cu and Cd, reaching maximum values of 64, 39 and 12 times its initial concentration respectively. Cortaderia Nitida turned out to be more efficient to recover Fe, Zn, Cu and Cr, with highest recovery of 250, 117, 39 and 13 times its initial value respectively. Finally, based on translocation factor, Stipa Ichu has better capacities of hyperaccumulation of Fe, Cu, Zn, Pb and Cr. Cortaderia Nitida only shows hyperaccumulation of Cr.

Mar 2, 2022

By Evan Dressel, Mark S. Diederichs, Kathy Kalenchuk

As hard rock mining develops deeper over time, there is an increasing need to predict the spatial and temporal distribution of adverse seismogenic rockmass reaction to mining. Real-time monitoring and feedback of mine data are used to tactically manage risk associated with induced-seismicity; however, strategic risk management requires reliable tools for forward predictions of seismic hazard. The forward prediction of seismic hazard is strengthened by understanding of potential seismic intensity, which often relies on well calibrated mine-wide numerical models. This paper uses a case study to explore how future seismogenic potential and the nature of future seismicity can be domained according to numerically predicted stress-strain paths at past seismic event locations. Delineation of high confinement seismogenic volumes vs. lower-confinement, high-strain seismogenic volumes at the mine-scale can be achieved, based on a loading and unloading stress path analogue, to refine understanding of seismic intensity. Practical qualitative and quantitative methods to achieve this delineation will be demonstrated. Once seismogenic mode (high-stress vs. high-strain) is identified, detailed analyses of seismic source parameters demonstrates change in seismic hazard between the domained volumes.

Apr 26, 2022

By T. Good

Twin roll sizers are neither compactly designed machines nor are they configured to accommodate underground mobility; in fact, twin roll sizers leave room for improvement in many aspects of the design. The DRC1200 capitalizes on the weaknesses of these machines to make a more productive, easily maintained, and compact twin roll sizer than current market offerings. These strides were made through the inception of the Hard Rock Extraction System (HRXS), which requires a mobile sizer as part of the system. After use of a third party sizer on the HRXS, potential improvements were evident. These improvements include improved structural design to reduce overall footprint and an optimized design to reduce operating cost.

Feb 23, 2014

By B. C. Lewis

The mining industry has experienced a general trend toward an increasing number of longwall operations, an increasing percentage of underground coal being mined by longwalls, and increasing productivity from the longwalls. Longwall operators have not yet reached a state of mining euphoria. Competitiveness both within the industry and from alternate fuel sources is forcing continued pursuit of higher productivities and lower costs. The following graphics present trends in the industry. Longwall mines, as defined for this presentation, are those reportedly having longwall installations in each of the respective years. Production from both the continuous miner and longwall units is included in the longwall mines. Non-Longwall mines are all other underground mines. Productivity calculations are based on total employee-hours associated with the operation.

Jan 1, 1990

By M. Rotz

In the minerals industry today, the ?low hanging fruit? that once existed to debottleneck production and improve recovery, while meeting market needs for quality in mineral processing operations, are more and more difficult to find. Systematic methods for establishing plant mass flow, recovery, operational efficiency and control strategy in context with customer specifications provides the necessary insight and confidence for plant operators to prioritize improvement projects in order to maximize return on investment (ROI) for the site. The evaluation of aggregate and industrial mineral processing plants requires the following steps when projecting cost saving opportunities: collecting background data, conducting a base-line evaluation, analyzing specific unit-operation performance, defining investment options, prioritizing the selected improvement opportunities and the implementing process changes. The following paper describes the approach and challenges of developing an improvement plan for a dry and wet mineral processing operation.

Feb 23, 2014

By J. M. Dean

The MANpower SUPport Program (MANSUPP), a part of the Mine Management Support System (MMSS), allows an underground coal mine site user to determine manpower requirements for production support work by considering ongoing operations and current mine conditions. The objective of MANSUPP is to plan a detailed manpower structure for a mine by incorporating a production schedule, condition-modified work standards and management preferences to predict required manhours for various activities, for example, belt moves. The program is written in Quattro Pro version 3.0 (Lotus 1-2-3 compatible) utilizing the command language, macro and formula capabilities.

Jan 1, 1992

By D. -P. Georgescu

A native sulfur mineralization associated with pyrite and iron oxides containing 20% iron was quarried in Calimani Mountains, Oriental Carpathians. The wastes resulted from this exploitation activity, with a volume of 33 millions m3, were stored in four dumps while the wastes resulted from ore processing using flotation and the subsequent treatment were disposed of in a settlement pond. The investigations carried out in the entire mining area focused on the following two aspects: - the impact of environmental factors mainly on the hydrographic network; - the characterization all pollution sources, namely dumps, leachates and the quarry and the assessment of acidic drainage generation. The total sulfur content of the excavated ore was 3.8% while in dumps it ranged between 0.54 and 1.06%. Analysis of samples collected along the hydrographic network, draining the mining area, resulted in pH values ranging between 1.7 and 2.83 as well as high concentration of iron (4525 mg/L to 1.6 mg/L), copper (1.87 mg/L to 0.04 mg/L) and zinc (13.13 mg/L to 0.3 mg/L). Samples from the quarry, the dumps and the tailings pond were analyzed in order to deter-mine: - the maximum potential acidity (MPA); - the acid neutralization capacity (ANC); - the net acid production potential (NAPP).

Jan 1, 2005

By J. Schoenbacher

Park City Municipal Corporation (PCMC), long before being recognized as an Olympic venue was known as one of the great American silver mining towns. During a century of active mining, the Park City mining district produced millions of ounces of silver in addition to a substantial amount of mine tailing waste. Since 1985 the City has been remediating these impacts with state and federal oversight. One particular challenging CERCLIS site, that was previously a historic mine tailings pond is known as Prospector Square Development (CERCLIS Listing Silver Creek Tailings UTD98051404). This site has been very challenging due to the metals that impact the shallow ground water that eventually drain into the Silver Creek Watershed. To address the water quality impairment the City and Missouri University of Science and Technology teamed up to investigate the feasibility of constructing a horizontal-flow wetland to treat this pollutant source. This effort began with the building of a pilot cell in June of 2004 and lead to the construction of a full scale horizontal-flow wetland in the fall of 2008. The design of the pilot and full scale biocell was based upon lab-scale research conducted by the Missouri University of Science and Technology. In October of 2008, the Prospector Drain effluent was introduced to the system and to date analytical results reveal that the biocell is treating the Prospector Drain outfall below the Silver Creek Total Maximum Daily Load (TMDL) endpoint goals for zinc .39 mg/L and cadmium .00075 mg/L. The water chemistry of the influent, that originates from the historic silver mine tailings pond, is impaired with zinc and cadmium and has low iron with a pH of roughly 6.5. The construction of this unit encountered many challenges related to constituent relations, regulatory scrutiny, constructability and start-up. Nonetheless, since implementation this unit is considered a success for improving water quality within the Silver Creek Watershed.

Jan 1, 2011

By Elwyn H. King, Thomas R. Kuesel

I. CONCEPT MARTA's Peachtree Center Station is being mined out of hard rock, directly beneath Atlanta's central business district, with minimal surface disruption during construction. Its cost is competitive with that of a conventional cut-and-cover alternative owing to its design concept, which utilizes the rock as a primary structural and architectural material. II. PLANNING The station was originally planned for cut-and-cover construction. However, Peachtree Street is unusually narrow for a main business street (generally 78 feet (24 m) between building lines) and cut-and-cover construction would therefore be very disruptive to surface traffic and severely restrict access to adjacent buildings, including Peachtree Center, Atlanta's showcase business/commercial complex. (See Fig. 1.) Tunneling had been considered, but was initially thought [ ]

Jan 1, 1979

By Joseph Matoney, B. K. Parekh

INTRODUCTION The term "dewatering" refers to removal of water from coal. Water associated with coal can be categorized as "free or surface" and "inherent or chemically bound" moisture.' The free moisture is found on the surface of coal, in capillaries and small spaces between two or more particles. The inherent or chemically bound water is found in the interior of the coal and as part of coal structure. A significant amount of free moisture can be removed by mechanical dewatering techniques. However, inherent moisture can only be removed by applying energy intensive techniques, e.g., direct or indirect heating. Moisture in the coal offsets some of the benefits of coal cleaning. Extra water in clean coal adds to extra cost in transportation, heat lost during vaporization, and plugging of chutes. From a utility perspective, a 1 % increase in moisture can offset a 4.5% decrease in ash.2 Mechanical dewatering can be classified into two major process categories according to the principles involved, namely, 1. Sedimentation-liquid is constrained and particles move freely. 2. Filtration-particles are constrained by a medium and the liquid flows through. Each of the process categories is composed of various separation techniques shown in Fig. Equipment currently being used by the mechanical dewatering of coal of varying size ranges and final moisture content is illustrated in Fig. 8-2. This figure indicates that sizes larger than 13/, in. (37.5 mm) present no particular dewatering problem. Shaker screens of the very crudest types and designs are capable of producing these sizes at low surface moistures. High-speed vibrators are used for the intermediate sizes and can be used for smaller sizes down to 0.02 in. (0.5 mm) if high moistures (15% surface moisture or greater) can be tolerated in the product. Usually, however, the vibrator is not used below 3/, to 3/, in. (9.5 to 6.3 mm) because of the moisture associated with these fine sizes. At this level, centrifugal force is usually employed to aid dewatering. Centrifuges of various types and designs are used practically

Jan 1, 1991

By R. K. Singhal

In an underground coal mining environment, a frictional ignition may be defined as the ignition of an explosive air/ methane/coal dust mixture by mining machinery. As the use of power loading equipment has become more widespread, frictional ignition incidents have increased. There have been many fatalities and injuries from this cause including the death of eleven miners in Sydney coalfield of Nova Scotia, Canada in 1979. This paper reports on the findings of a preliminary study carried out under the auspices of the Coal Research Laboratories, Department of Energy, Mines and Resources Canada. The objective of this study has been to identify a Longwall face cutting system that is inherently safer than the conventional shearer loaders used in Nova Scotia.

Jan 1, 1985

By J. R. Heberger

"The Safety Pays in Mining web application, developed by the National Institute for Occupational Safety and Health (NIOSH) Mining Program, helps mines determine the potential costs associated with mining injuries. This web app groups injuries by type, either by the cause of the injury or by the nature of the injury. When the user selects one of over 30 common types of mining injuries, the app provides information on the distribution of costs of workers’ compensation claims for that type of injury. Based on other user inputs, Safety Pays in Mining will estimate the total costs of the selected injuries, including an estimate of additional indirect costs, the estimated impact of total injury costs on mining company profits, and provide some examples of other items (services, equipment) on which companies could spend the savings that result from the prevention of injuries. This paper reviews the Safety Pays in Mining web application by discussing the development of the app, how it is used to show the true costs of mining injuries, and how mines can benefit from using this app. INTRODUCTION Injuries on the job cause pain and suffering. They can also profoundly affect profits and daily operations. In addition to paying direct costs or increased premiums for workers’ compensation insurance, a company might need to pay overtime for other workers to fill an injured worker’s job role, cover training costs for a replacement worker, or divert administrative resources in the wake of an injury. Safety Pays in Mining is a web app that estimates the distribution of these injury costs and assesses the impact that occupational injuries have on a company’s profits. The costs of specific types of occupational injuries in mining are not readily available as mining and insurance companies don’t usually share this information. As a consequence, companies only have cost information based on previous experience with their own employees. Therefore, if a mine never experienced a finger amputation for one of its miners, it would not be aware of the possible costs associated with this type of injury. In addition, injury costs are unique in that the cost distribution is so wide — with half of the injuries in our dataset having mean costs higher than 90th percentile costs — just using the average cost of a specific injury type does not provide adequate information. Some injuries involve immensely high costs, and even though the risk of these high-cost injuries occurring is low, mines need to be aware of their potential impact on their company’s financial health."

Jan 1, 2018