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By T. R. Hughes

How do you fit a processing plant underground with minimal change to mine infrastructure and yet maintain economic recovery, operability and maintainability? By combining fine crushing, continuous-gravity recovery and flotation. A modular, transportable processing plant has been designed that is capable of being installed in underground drives/drifts or on the surface. The Python processing plants have been designed to treat 20 or 50 tons per hour of ore to a particle size of approximately 500 µm and recover gold and sulfides into the concentrate. The plant is only three meters wide (including bolt-on platforms) and can be installed on a 1:50 slope, making for very simple installation. Test work carried out by Gekko Systems Pty. Ltd. has indicated that up to 50% of ores tested to date would achieve gold recovery rates of over 90% using this method. The projected benefits of this strategy are numerous and include low overall capital and operating cost, significantly less power consumption compared with traditional milling circuits and low environmental footprint.

Jan 1, 2010

By A. W. Mitchell

Mining of a bedded barite deposit exposed highly pyritic siliceous sediments which have weathered and degraded subsurface and surface waters. The ph, sulfate, and total dissolved solids are the most seriously affected parameters. Several solutions were tried and eventually horizontal holes were drilled into the mine wall to draw down the water table and decrease the movement of groundwater through oxidizing zones opened up by the mining operation. Areas of surface disturbance were capped with layers of soil, bentonite, and gravel to decrease the infiltration of water into the disturbed areas. These actions have begun to decrease sulfate and total dissolved solids concentrations and increase ph values.

Jan 1, 1987

By M. Yekich, W. R. Reed, G. Ross, M. Shahan

"Canopy air curtains on roof bolting machines have been proven to protect miners from respirable dust, preventing their overexposure to dust. Another desired application for canopy air curtains is in the compartments of shuttle cars. The challenges faced in developing the design of canopy air curtains for shuttle cars include mine ventilation rates in tandem with the shuttle car tram speeds. The resulting cab airspeeds may exceed 182 m/min (600 fpm), as found in the present study conducted in a central Appalachian underground coal mine by U.S. National Institute for Occupational Safety and Health (NIOSH) researchers. Prior research and laboratory testing had indicated that successfully protecting a miner in high air velocities is difficult, because the clean air from the canopy air curtain is unable to penetrate through the high-velocity mine air. In this study, the dust concentrations to which a shuttle car operator was exposed were measured, and air velocities experienced by the operator were measured as well using a recording vane anemometer. The results indicate that the highest exposure to respirable dust, 2.22 mg/m3, occurred when the shuttle car was loading at the continuous miner, where the average airspeed was 48 m/min (157 fpm). While tramming, the operator was exposed to 0.77 mg/m3 of respirable dust with an average airspeed of 62 m/min (203 fpm). This study indicates that a canopy air curtain system can be designed to greatly reduce an operator’s exposure to respirable dust by providing clean air to the operator, as the majority of the operator’s dust exposure occurs in air velocities slower than 61 m/min (200 fpm). IntroductionThe U.S. National Institute for Occupational Safety and Health (NIOSH) issued contract #200-2015-63485 to develop a canopy air curtain for coal mine shuttle cars with Marshall University and J.H. Fletcher & Co. (Salem, Begley and Ross, 2016). The proposed design maintains a design similar to that of a roof bolter canopy air curtain by providing filtered air through a blower over the operator. The plenum, which will provide uniform airflow over the operator, is anticipated to be built into the shuttle car canopy. One of the main interferences with a canopy air curtain is ventilation airflow perpendicular to the plenum airflow (Engel, Johnson and Raether, 1987). This ventilation airflow can shear the downward flow from the plenum, and this shear can reduce the effectiveness of the canopy air curtain by either disrupting the downward flow or allowing contaminated mine air into the canopy air curtain zone of protection."

Jan 11, 2018

By J.N. Kohmuench

Teeter-bed (i.e., hindered-bed) separators are used throughout the mineral processing industry for both classification and density separation. The high capacity and sizing characteristics of these units make them ideal for feed preparation prior to coarse flotation (+0.100 mm) circuits. Teeter-bed separators are typically easy to control with two basic operating parameters, including fluidization water rate and bed level. However, data show that these two parameters greatly interact with one another. Given this finding, a high-level automatic control scheme was developed and implemented on a full-scale separator. In addition, dialogue with plant operators has led to several simple changes to an already established design that improves operational and maintenance characteristics.

Jan 1, 2010

Thermal pretreatment can significantly improve industrial comminution operations by reducing energy requirements and increasing mineral liberation. The effect of pretreatment using conventional and dielectric heating followed by quenching on the fracture properties of a number single and multiphase brittle materials has been investigated. The reduction in the impact fracture energies and particle strengths with and without pretreatment has been measured in precise single-particle experiments using the Ultrafast Load Cell. Variations in the fragmentation pattern caused by different pretreatments were assessed by measurements of the progeny size distributions. The differences in the effect of thermal treatment on single and multiphase materials are discussed based on the experimental results.

Jan 1, 1995

By C. D. Secrest

Visiting Spring Canyon, a historic coal mining district near Helper, Utah, I was impressed by the great accomplishments that had taken place there. A tour book of the region tells of a period that began in the early 1900's, when the land was still very much the Old West, when settlers lived out their lives in coal company towns and produced a resource that was to build a nation (Cunningham, F., 1990). Between 1912 and the early 1970's, 11 mines had come and gone in that narrow canyon less than 15 kilometers long. Spring Canyon is a historic district now, but I could not dwell too long on the richness of its history. I was there to look for evidence of PCBs.

Jan 1, 1993

By Dennis Greene

Real-time GPS position monitoring of mining equipment is becoming more and more commonplace. Digital mining plans can now be used onboard properly equipped earthmoving equipment and excavation status is available in real-time via high bandwidth data radio systems. These systems provide a closely integrated link between operations and planning. No longer must operations wait for or be hindered by insufficient survey marks, nor is engineering delayed by lack of timely mine status information. Unprecedented efficiency gains become feasible -from the engineering office, to drilling and mucking, to reclamation, as well as in mine construction projects. Direct economic benefits of these systems will be explored as will the less tangible, but very significant, indirect operational efficiency gains.

Jan 1, 1998

By David D. Eyer

In today's world coal market, coal quality is becoming increasingly important. Often the coal quality parameters are one of the crucial considerations in the development of a coal mine. Because of the user's tighter specifications and because of strict environmental regulations, coal producers are being called on to predict with increasing accuracy, not only the quality of their product but also the variability of that quality. This area of reserve evaluation is naturally receiving a great deal of scrutiny. Consolidation Coal Company has developed reliable and sophisticated methods for predicting coal quality, but the company's efforts continue to search for even better techniques. The following is a step-wise summary of The methods currently used by consolidation coal company, with A recent project used as an example. Two of the newer, and as yet experimental techniques will be briefly discussed.

Jan 1, 1980

By R. Mathur

Cu isotope fractionation in low-temperature aqueous environments has been well documented. Here Cu fractionation was applied to two distinct, yet related, mining problems. First, an exploration geology application, where copper isotope fractionation was measured in oxidized leach caps, chalcocite enrichment blankets and hypogene mineralization in three porphyry copper deposits located in the southwestern U.S. Cu isotope patterns exist in a vertical distribution within the mines, coupled with distinct relationships with the Cu grade. Second, a hydrometallurgical application, where copper isotope fractionation was measured in leach fluids, feed and residues from a quick leach test (QLT) on Cañariaco, Peru ores. The results indicate the relative proportions of the minerals providing Cu during leaching. Interpretations of the QLT test measurements indicate covellite is the dominant ore mineral providing Cu during leaching. Both applications clearly demonstrate the use of the Cu isotope technique to understand low-temperature aqueous processes involving copper.

Jan 1, 2012

By P. Kawahata

Newmont?s Twin Creeks Mine, located in northern Nevada, is producing gold ore from surface mining operations. The ore is currently processed at three different on-site facilities depending on ore type and grade. Processing facilities operate under stringent geochemical blending constraints that must be met from mine ore deliveries and off-site sourced ore. To analyze various strategic options, the technical team utilizes the mathematical optimization approach. However, due to the size and complexity of the operation, there are unique challenges in optimizing life-of-mine production scheduling. This paper describes those challenges and methods developed to take advantage of different scheduling software to effectively compensate each other and result in reasonable guidance. This paper also describes how those scheduling results are reflected in detailed mine plan and cost estimate work.

Jun 1, 2013

By R. Freer

Recent developments in expanded PTFE membrane filter cloths offer high flow rates and sub-micron particle removal. These high strength, industrial grade filter cloths can be tailored for tubular filters, leaf filters and rotary vacuum drums. Filtration techniques using tubular filters make possible filtration of difficult slurries with the elimination/reduction of filter aids and chemical additives. This paper describes principles of surface filtration, applying the membrane filter cloth and comparisons to gravity separators. Benefits to the mining industry include clear effluent, enhanced solids recovery and accelerated cost payback.

Jan 1, 1996

By G. Hwang, S. Park, H. Kim, J. Choi, P. Seo

"In the mineral processing, clay minerals have negative effects on the flotation of valuable minerals. In this study, we investigated how the floatability of malachite (CuCO3·Cu(OH)2) is affected by presence of the clay minerals in the fundamental aspects. Flotation experiments were conducted by using Na2S and PAX (potassium amyl xanthate), and the floatability of malachite was compared between the cases in the presence and absence of clay minerals. The results showed that floatability was greater in the absence of clay minerals than in the presence of clay minerals and decreased with increasing weight percent of kaolinite under same conditions applied. In addition to examine how clay minerals affect malachite floatability, we conducted flotation experiment with changing clay adding order. The results indeed showed that malachite floatability was affected by clay adding sequence. INTRODUCTION The demand of copper is growing as industrial development increases, but mineral resources are limited. Therefore, studies for Cu oxide flotation are being conducted to improve their recovery(1-3). However the mining industry is well aware of the difficulty in treating copper ores in the presence of clay minerals(4). Clay minerals have unique properties and these properties may affect flotation. In the previous studies, the effect of slime coating of clay minerals on flotation was investigated(4-6). For example, Zhao and Peng (2014), Peng and Zhao (2015), and Arnold and Aplan (1986) found that clay slime coating on chalcopyrite, chalcocite and coal surfaces through the electrostatic attraction reduced surface hydrophobicity and then depressed the flotation. Other researchers have also reported clay minerals have impact on pulp rheology. Especially in the case of bentonite, pulp viscosity increased with increasing amount of bentonite and the higher pulp viscosity have deleterious effect on copper recovery(7, 8). However, these studies only focus on slime coatings and pulp rheological behavior. Forbes et al. attempted to decoupling rheology and slime coatings effect on flotation but this study has limitation that individual role of two clay species either attached to mineral or suspended in bulk solution was excluded(9). Hence, in this study, we aimed to investigating the effects of individual clay (suspended and attached) on malachite flotation."

Jan 1, 2016

By A. L. Ling, A. K. Janzen

"Design of effective mine water treatment plants depends on the ability to reliably predict treatment outcomes, but systems with multiple chemical and physical treatment processes and recycle loops can be difficult to model. GoldPHREEQC is a modeling framework that integrates mass and flow routing capabilities of GoldSim software and water quality calculations provided by PHREEQC, and is well-suited to modeling parameters of interest in the mining industry, especially metals and sulfate. Physical processes such as membrane separation and greensand filtration are modeled by defining mass rejections for each parameter and flow routing based on vendor projections and bench- or pilot-scale equipment testing. GoldPHREEQC models chemical precipitation processes such as HDS metals removal and gypsum precipitation by (1) performing surface-aging and solubility calculations in PHREEQC and (2) using the GoldSim framework to direct supernatant and precipitate to subsequent process steps. Users can apply this modeling framework to predict effluent water quality, chemical requirements, sludge production, and required equipment capacity to support design, troubleshooting, and cost estimating. INTRODUCTION Design of effective mine water treatment plants depends on the ability to reliably predict treatment outcomes, but systems with multiple chemical and physical treatment processes and recycle loops can be difficult to model. GoldPHREEQC is a modeling framework that integrates mass and flow routing capabilities of GoldSim software (1) and water quality calculations provided by PHREEQC (2), and is well-suited to modeling treatment of parameters of interest in the mining industry, especially metals and sulfate. GoldPHREEQC can also be applied to other water treatment scenarios using inorganic reactions and processes. The GoldPHREEQC model framework moves water and mass between specified model nodes and calculates specified reaction and water quality outcomes. It can be organized to provide flow, load, and concentration information for each location, including effluent and byproduct streams, and outputs can be adapted to include power and chemical costs."

Jan 1, 2018

By Melvin W. Kraschnewski

In 1966 Central Ohio Coal Company and Bucyrus-Erie signed a contract authorizing Bucyrus-Erie Company to design and build a 220 cubic yard dragline. This dragline would be used for stripping overburden from their coal reserves located near Cumberland, Ohio. The size of the machine was arrived at after a thorough application study of their annual coal output requirement, depth of overburden and type of terrain. The design and construction of this machine which has been designated by BECO as model number 4250-W is the title of this paper. Size wise based on machine weight the 4250-W represents an increase factor of three over our largest current dragline. Probably the easiest way of presenting a machine of this size is to build it from the bottom up.

Jan 1, 1969

By C. McAllister, D. Preece, J. Berendzen

"The Multiple Blasthole Fragmentation (MBF) model models multiple explosive charge contributions and the effect on fragmentation of delay timing with its associated scatter for each blasthole. The model uses near-field blast vibration attenuation parameters and the ground p-wave velocity as inputs for part of the in situ rock property to model rock fragmentation. It models most blast design parameters explicitly and simulates the effect of wave reinforcement due to the interaction of simultaneously arriving waves or diminishing cooperative contribution from long delay intervals between charges within a blasthole or among blastholes. The fragmentation size is calculated at three-dimensional grid points within a blast, and the fines and oversized blocks are treated explicitly. The model takes a surveyed irregular geometry of the free face of a blast as the calculation boundary.This paper presents a case study on applying the MBF model at an openpit mine. Near-field vibration measurements from signature hole blasts were conducted to obtain the stress-wave magnitude and attenuation parameters as well as ground sonic velocity. A production blast was then monitored with the corresponding fragmentation measured, serving as site-specific inputs to the MBF model. Various blast design scenarios were then simulated to develop ones that provide better fragmentation to improve mill throughput for the mine. IntroductionThe semiempirical fragmentation models currently found in the literature (Cunningham, 1987; Lownds, 1995) cannot explicitly model contributions from multiple blastholes with varying delay intervals. Most of these models are not three-dimensional. Furthermore, these models predict an average fragmentation size within a volume surrounding a blasthole and use the average size to generate a size distribution over the volume. The percentage of fines and oversize blocks is included in the distribution. Typically, such models are inadequate for predicting fines and oversize blocks (Cunningham, 1987)."

Oct 1, 2016

By B. H. Kim, P. Zhang, M. A. Van Dyke, D. Su, H. Dougherty

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a postmining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64 degrees, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457 m wide and 3657 m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones

Mar 2, 2022

By Charles W. Daugherty, Eugene B. Waggoner

In the construction of recent subsurface projects, particularly mined openings and transit systems, it has been apparent that final costs were often greater than first expected. Because many overruns result from alleged differing site conditions, there was reason to suspect that pre-bid geotechnical investigations were inadequate for predicting subsurface geology. In 1982, nine federal agencies involved in constructing underground facilities funded the National Academy of Sciences' U.S. National Committee on Tunneling Technology (USNC/TT) in an effort to evaluate and clarify the relationship between geological knowledge and construction costs. That committee formed the special Subcommittee on Geological Site Investigations, which spent more than two years studying underground projects by examining contract documents and geologic reports, making site visits, and interviewing owners, designers and contractors. The study ultimately encompassed 84 mined tunnels and chambers and three deep shafts in the United States and eastern Canada. Data collected on geologic exploration, design and construction were analyzed and conclusions reached concerning whether and how site investigations need to be improved. The results of the study are published in two volumes by the National Academy of Sciences. Due to the recent completion date of the main report, it was not possible to prepare a summary for inclusion in the RETC Proceedings. However, the complete two-volume report, "Geotechnical Site Investigations for Underground Projects," can be obtained by writing or calling: U.S. National Committee on Tunneling Technology National Academy of Sciences 2101 Constitution Avenue, N.W. Washington, D.C. 20418 (202) 334-3136

Jan 1, 1985

By Cyril Heever

ROCKS outcropping in Elandsrand's lease area consist of quartzite, shale and lava of the Pretoria group and are underlain first by 1 300 metres of dolomite and then by the Black Reef series. This in turn rests unconformably on Ventersdorp and Witwatersrand rocks and truncates the basal member of the Ventersdorp Super group, the Ventersdorp Contact Reef (VCR), near the northern boundary of the lease. The Ventersdorp Super group is composed of lava and varies in thickness from nil in the north of the lease area to 1 000 metres in the south. The VCR, less than 100 cm thick, dips 210 to the south east and lies between 1 786 and 3 386 metres below datum. The Oberholzer dyke straddles the north-western corner of the property and separates the dewatered Oberholzer compartment, over which most of Elandsrand lies, from the as yet undewatered Turffontein compartment. As so much of the lease area is covered by thick impermeable rocks, the water-bearing capacity of the underlying dolomite was expected to be low. The man-material (MM) and rock hoisting ventilation (RU) shafts were sited well within and above a gravimetrically determined 200-metre 'safe-limit' contour of the northern slope of the Gatsrand. Two pre-cementstion holes were drilled and the cementation rigs were placed within a 15 metre annulus round each shaft to seal any likely water-bearing pockets in the proximity of the excavation during sinking through the first 300 metres of shales and the surface water-table.

Jan 1, 1981

By R. A. Pond

Two 6.17 m (20 ft 3 in.) diameter raises, concrete-lined to 5.49 m (18 ft) inside diameter, were completed in 1978 at the Monterey Coal Company Number One Mine near Carlinville, Illinois, by Frontier-Kemper Constructors. These two raises are the largest in cross-section yet completed by full-face upreaming, and the success of this project is expected to increase the application of raise-boring to coal mine shaft construction. WHY 6.17 M (20 FT) DIAMETER ? Raise boring is well accepted in the metal mining industry for a variety of applications, and is gaining in acceptance in the civil works construction industry. The use of raise boring to construct vertical openings for coal mines has not been as widely accepted, even though coal mining requires, per mine, the greatest number of openings to the surface of any underground activity. Several factors have influenced the low utilization of raise boring in coal mining: 1. Coal mine shafts must often be of large diameter to pass the required high volumes of ventilation air at acceptably low water gage pressures. Cross-sectional areas of finished shafts exceeding 23.23 sq m (250 sq ft) are common. 2. The life of ventilation shafts is comparatively long, and the typical sedimentary strata overlying coal seams normally require that the shafts be lined. Shafts on the intake ventilation circuit must have permanent water-tight linings. 3. Unconsolidated overburden at the surface is often thick, and as reaming cannot be safely utilized in unconsolidated material,

Jan 1, 1979

By G. A. Campbell

This paper considers the international market trends of the rare earths and how they are strongly influenced by the by-product/co-product nature of their mining and processing. The two main economic minerals for the rare earths are bastnasite and monazite. Monazite is primarily a by-product of mining ilmenite and rutile and is affected by changes in these markets as well as the presence of thorium. Bastnasite is a by-product of mining iron ore in China and a stand-alone product in the USA. The paper will use conceptional relationships and empirical data to delineate the various by-products/co-products relationships and how they determine observed international market behavior.

Jan 1, 1996