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By Paul Headland

The Washington Suburban Sanitary Commission (WSSC) has recently completed design for the Bi-County Water Tunnel Project. The project will include a 10-foot diameter, 5.3-mile long hard rock tunnel located within the Piedmont Physiographic Province in Montgomery County, Maryland. The rock formations present along the alignment are comprised of igneous and metamorphic lithologies. This paper presents the steps taken to characterize the complex geology along the tunnel alignment into a single ?Engineering Unit? based upon the intact rock and rock mass properties. The Rock Mass Rating (RMR) system is planned to be used as the basis for dividing the ground into three ?Excavation and Support? classes. This RMR approach was selected to establish contractual baselines as presented in the Geotechnical Baseline Report (GBR) and is intended to facilitate management of the ground support characterization during construction.

Jan 1, 2008

By James L. Poole

The gold and silver markets from the late 1960's to the present are reviewed and the outlook for these metals in the 1980's is presented. Included in this discussion is a summary of the basic supply and demand balance for gold and silver since the mid-1960's. an explanation of the price formation for the metals, some of the relationships between the prices of these metals and selected economic parameters, and how these factors affect the outlook.

Jan 1, 1981

By R. N. Powell

The Pipeline ore body was discovered in March 1991. The construction of the new mine and mill did not start until early March of 1996. Upon completion of permitting and corporate project approval, the 289 million USD project was “fast tracked”. The commissioning began 11 months after start of construction and the project ended 40 million USD under the budget figure. The objective of this paper is to review and highlight the Pipeline Project history from discovery, design, lawsuits, permitting, and re-design through to current - 1998operating practices. Particular emphasis will review the process design, design mistakes, and design successes. The paper will review project history, feasibility, design concepts, operator training, construction, financial and the current operation. Additional discussion will review what design features worked and which did not work within the process plant.

Jan 1, 1999

The minerals industry consumes billions of dollars in raw materials, equipment, tools, services and chemicals. The industry, though, has turned overmuch of the research and development (R&D) for these products to manufacturers and suppliers. Now the industry and its suppliers must decide how much R&D the mining industry should be responsible for and what role the suppliers should play. Promoting R&D As a result of the current environment in the mining and minerals industry, there has been a substantial decrease in R&D. Depressed prices, stagnant growth, cost cutting and rationalization are evident.

Jan 1, 2000

By Stanley Lefond

The health of the industrial minerals industry appears to be improving year by year. In fact, preliminary information suggests that only three commodities (asbestos, bromine, and sulfur-other) failed to show a production gain in 1984 over 1983. In 1983, 10 commodities failed to post gains and six remained constant. The total value of industrial mineral production in 1984 was $16.7 billion, up $1.4 billion from 1983. Cement, clays, gypsum, and crushed stone production increased. Since these are used in housing and construction, this suggests these industries are moving out of their recent doldrums. Barite and clay production also improved in 1984. Local US barite production, however, still has a long way to go to attain the 1981 high of 2.6 Mt (2.9 million st). Barite imports remain high. But they are not as high as the 1982 importation of 2 Mt (2.3 million st). Bentonite production in 1984 increased 20% in volume and 25% in value over the previous year. This suggests improvement in the drilling industry and an increase in demand for iron ore pelletizing grades. All in all, the industrial mineral industry is alive and well. And it shows signs of great improvement in the next few years. Many thanks to those industrial mineral technical committee members for their assistance in assembling this industrial minerals review: M. F. Dibble, H. W. Allen, G. H. Gallup, S. G. Ampian, D. W. L. Spry, H. G. Fleshman, and L. J. Czel.

Jan 5, 1985

By Todd S. Webster, Matthew J. Pierce, Brad D. Krumel

With the Working Shafts and Starter Tunnel under way, it became apparent this 4.7-mile, 19-foot diameter wet weather tunnel was going to live up to its name. The shaft’s pre-excavation grouting was completed, and ground water inflows were slowing project progress. As the tunnel drive was approaching 50% complete a cooperative effort was underway between the owner, engineer, and contractor to raise the base of the Retrieval Shaft by 65 feet to avoid ground water infiltration construction challenges. The tunnel alignment needed to be raised in kind. The project was behind schedule and rethinking the cast-in-place adit work was next on the agenda due to the very wet environment in the tunnel. The race was on to finish the project within the owner’s time constraints while completing multiple redesign aspects of the tunnel alignment and associated adit construction. This paper will evaluate original design criteria and actual in-route design modifications and change management to meet the owner’s just-in-time schedule needs.

Dec 1, 2022

By Wei Victor Liu, Na Zhang, Chengkai Fan, Bei Jiang

The truck haulage data from open-pit mine sites are usually massive and multidimensional with multi-peak Gaussian distributions. Artificial neural networks (ANNs) are well-known machine learning algorithms to handle massive and multidimensional data for building models. Moreover, Gaussian mixture modeling (GMM) is a suitable option for processing the data under multi-peak Gaussian distributions and improving model accuracy. For the first time, this study used a back propagation neural network (BPNN), an extreme learning machine (ELM), and a Bayesian regularized neural network (BRNN) coupled with GMM to deal with the complex truck haulage data and build three weighted ensemble models (WE-BPNN, WE-ELM, and WE-BRNN models) to predict truck productivity at mine sites. Decision tree (DT), random forest (RF), gradient boosting machine (GBM), and extreme gradient boosting (XGBoost) were used to build models to be compared with the weighted ensemble models. The results showed that the WE-BRNN had a higher accuracy than the WE-BPNN and WE-ELM models. The proposed weighted ensemble models performed better than the benchmark models in predicting truck productivity, indicating that a weighted ensemble approach based on the GMM analysis significantly improved the model accuracy. Based on the relative importance analysis, haul distance was the most crucial input variable for predicting truck productivity. This study provides a new approach to predicting truck productivity, which will help mining companies make sound budget decisions and improve mine planning.

Mar 2, 2023

By Amar Prakash, V. M. S. R. Murthy, Ajoy Kumar Singh, Avinash Paul, John Loui Porathur

Weak, layered, and fragile rock mass formation, if not supported properly, is subject to roof failure thereby affecting safety and productivity in underground coal mines. Though Central Mining Research Institute – Indian School of Mines Rock Mass Rating (CMRI-ISM RMR) based well-defined support design guidelines are established, still occurrence of roof failures in underground coal mines is a real matter of concern for mining engineers and researchers. Numerical modeling techniques are successfully used by several researchers by simulating rock mass condition for stability assessment of mine openings. The analysis becomes crucial in case of weak and fragile rock formation. The present research envelops the determination of 31 cases of rock load by CMRI-ISM RMR under different geo-mining conditions followed by the development of modified Rock Mass Rating (RMR), i.e., rock mass rating dynamic ( RMRdyn) by incorporating P-wave velocity as a new parameter. The rock load determined using RMRdyn and numerical models was correlated and found in close agreement. In addition, the deviation in rock load determined by all the three approaches, i.e., CMRI-ISM RMR, numerical modeling, and RMRdyn, was compared with the actual field data. The percentage deviation obtained in RMRdyn and numerical modeling is less compared to CMRI-ISM RMR.

Sep 1, 2023

By Kevin Andrews, Terry Hamric, Scott Nelson

"Mining conditions in underground coal mines are dictated by the environment in which the coal seams were geologically deposited. Depositional features can change rapidly, significantly affecting mining conditions. Mine geologists understand factors affecting mining conditions, predict future conditions, and provide guidance to mine management. A case study demonstrates how a mine in Appalachia merged an understanding of depositional environments with mining conditions and drilling data to make informed decisions as the mine encountered geologic anomalies. The assessment included drilling, mapping of geologic hazards and mine productivity, and creation of a conceptual depositional model. Metallurgical coal quality and clean tons per foot served as incentives for continued advance. Mining in the south was historically favorable, with good production and advance rates. As mining advanced north, changing geologic conditions caused the upper seam split to abruptly disappear. The mine ramped down into the lower seam split. Mining in the north area encountered unfavorable conditions, including transition roof, “horsebacks,” sandstone intrusions, roof rolls, and bony floor, resulting in low rates of mining advance. The mine geologist characterized the features and created a predictive model for future mining. Most of the adverse conditions were attributed to the coal in the north being part of an incised, transgressive valley fill environment, as compared to the favorable conditions in the south resulting from a floodplain depositional environment. Geologic conditions, low productivity, and unfavorable future predicted conditions in the north ultimately resulted in mine closure and reallocation of resources to a new mine with better forecasted conditions.INTRODUCTIONThe role of a geologist in assisting coal mining operations to understand and predict the impact of varying geological factors on mining productivity is a critical one, especially when management decisions must be made about the future prospects of a mine operating in difficult conditions. Chase, Newman, and Rusnak (2006) provide a very thorough discussion of the evolution of the role of the coal mine geologist and emphasizes the importance of understanding geology with regard to mine management decisions. Using actual mining performance data to determine which geologic factors are the most critical for mining is a powerful tool for making informed mine management decisions. For example, Nelson, Mullennex, and Miller (1988) provide a case study of analyzing the geologic factors impacting productivity of a Kentucky longwall mine to predict future mining conditions for the operation. In that case, the difficult geologic factors for longwall mining were prevalent across much of the remaining permit area and, in response, mine management converted the operation from a longwall operation to a continuous miner (CM) operation to better adapt to the geology. In another example, Keim and Miller (1999) evaluated geologic conditions impacting a West Virginia longwall mine. In both examples, significant geotechnical and geological information was available, including the opportunity to compare predicted mining conditions against actual conditions as mining progressed. Numerous examples of advanced Geologic Hazard Mapping (GHM) methodologies have come from government agencies and academia. For example, development of the Coal Mine Roof Rating (CMRR) system (Molinda and Mark, 1994) provided a standard means for geologists and engineers to communicate quantitatively with regard to mine roof conditions, and the introduction of the Stability Mapping System (SMS) provided an efficient means for analyzing numerous factors affecting coal mine stability (Wang and Heasley, 2005)."

Jan 1, 2019

By Anthony D. Hammond

The use of geographic information systems (GIS) as a tool to analyze and display data is gathering momentum in the mining industry. Of particular interest is the capability of GIS to link spatial features and tabular data. The application of GIS in underground mining discussed here concentrates on four technical areas. They are land ownership and mineral claims, exploration management, production and mine safety.

Jan 1, 2002

By K. Wenrich

The uranium industry has made a dramatic turnaround in the past three years that even the most optimistic economist was not willing to predict during the uranium downswing of the 1990s. Uranium reached a 30-year low in February 2001 of $6.50/lb. By the end of February 2006 it had soared to $38.50/pound. This nearly 600% increase in the uranium spot price within 4 years dwarfed the increase in gold price that has barely mustered a 100% increase. The initial slow rise from $6.50 in February 2001 to $10.75 in April 2003 (fig. 1) was primarily driven by the decrease in the value of the dollar. Since then several factors have contributed to the soaring price: (1) The awakening of many to the simple fact that uranium supply has not met demand for several years and that the world’s stockpiles are being drawn down, (2) How sharply this fragile supply can be impacted by disasters at the world’s major uranium production facilities, such as a) the flooding of the McArthur River Mine in the spring of 2003, b) fires at Olympic Dam, c) the potential that Rossing, with an annual capacity of 4000 tonnes uranium might close by 2007, (3) the withdrawal of Tenex from the HEU (highly enriched uranium) feed agreement, and (4) the announcement by the Chinese of their intent to build 30 new nuclear reactors.

Jan 1, 2007

By R. Fuenzalida

Since 2007, a number of Multivariable Predictive Control (MPC) Applications have been implemented on SAG mills, among others, within the Kairos Mining Concentrator Automation Program using ?Profit Controller?? and other tools comprising the ?Profit Suite??. Along this journey, several interesting and challenging issues related to SAG mill operation and control have been faced, which are relevant to be shared with the Mineral Processing community. These advanced control applications have an operational objective whose goal is to increase marginal profit on the concentrator, together with increasing mill stability. In regard to this objective, the issues to be presented and described are in direct relationship with ?Profit Controller? features and the SAG role; they are also stated and linked to get the most of the mill. Some conclusions and findings are also presented, leading to recommended practices on how to use the controller. These findings have also lead us to decide further actions to be taken on new applications to deploy and also on devising and implementing some complementary components to increase robustness of the overall automation solution, as well as reducing the need for operator intervention.

Jan 1, 2012

By D. Dimitriadis, T. Polglase, W. Phillips, R. Jenny, M. Botz

Cyanidation processes for the extraction of gold or silver frequently involve the processing of sulfur-containing solids which react with cyanide to form thiocyanate. The formation of thiocyanate is an undesired side-reaction, and in many cases thiocyanate formation results in a prohibitively high cyanide consumption. With the increasing number of gold and silver mining projects which involve the processing of sulfide ores or concentrates or which utilize a biological sulfur oxidation process, more attention has been focused on minimizing thiocyanate formation and in treating solutions to eliminate toxicity associated with thiocyanate. Though not yet commercially applied, there are several technologies available to recover cyanide from thiocyanate to both reduce tailings toxicity and allow the reuse of cyanide otherwise lost to thiocyanate formation. This paper presents an overview of technologies available for recovering cyanide from thiocyanate along with estimated operating costs for the technologies. Pilot testing data suggests that in some cases, cyanide can be recovered from thiocyanate for approximately the same cost as newly purchased cyanide.

Jan 1, 2000

By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

Multilevel-multiseam hardcoal mines on the European continent usually consist of a huge network of underground openings, sometimes more than 200 km long in total, with some longwalls operating down to a depth of 1,500 m. While operating several longwalls simultaneously, these mines are making use of a number of stationary and mobile measurement- and analysis units in their main ventilation passes combined with atmospheric measurements on the surface. This paper provides an overview over the systems and technology used and describes the typical set-up of a measuring net. To detect and monitor underground fires through fire gases measurement and -analysis, a mobile underground testing laboratory collects data locally in the area of the fire. These laboratories have proven to be extremely useful not only during the actual fire fighting but also for the long-term gas measurements in critical mine areas. They have repeatedly detected starting fires and have thus given the mine the opportunity to react early and to avoid larger damage. Therefore several mobile laboratory units have now been installed for long-term testing in a number of German mines and similar units are being used in the Czech Republic and Poland.

Jan 1, 2012

By James A. Madonna

Information gathered while studying geological parameters that govern fine gold deposition in the a1luvial environment can be applied to the technological development and selection of fine gold recovery systems. It is recognized that substantial gold losses occur in the minus 1.5 mn (minus 12 mesh) fraction using conventional sluicing systems. Within the past two decades much attention has been given the design and efficiency of these thick bed concentrators. Studies and comparisons drew information from several foreign and domestic placer operations. These studies concentrated on: 1) the physical and chemical properties of alluvial gold 2) the parameters that control fine gold deposition 3) the geometrical form, components and general working structure of conventional sluicing systems 4) the physical properties which contribute to the overall efficiency of a sluice system 5) the comparison of three major styles of conventional sluicing systems. A dramatic improvement regarding fine gold recovery and water quality was observed when using modern multiple-channel sluicing systems in place of conventional single-channel sluicing systems.

Jan 1, 1988

By MOHAMMAD R. H. GORAKHKI, CHRISTOPHER BAREITHER, MANUEL APARICIO, IV JOSEPH SCALIA

Comingling filtered tailings and waste rock in a tailingsdominated mixture is a mine waste management strategy that has the potential to create geotechnically and geochemically stable landforms. Potentially acid-generating (PAG) waste rock can be sequestered within a filtered tailings matrix to enhance water retention and decrease hydraulic conductivity relative to a waste rock pile, potentially minimizing acid rock drainage (ARD). Enhanced water retention can reduce oxygen ingress limiting oxidation and resultant acid generation. Reduced hydraulic conductivity can slow inward percolation and outward drainage. In dry climates, the tailings matrix can hold precipitation near the ground surface accessible to evaporation and transpiration, thereby decreasing percolation. This paper presents an evaluation of comingled filtered tailings and waste rock in a tailings-dominated mixture (termed GeoWaste herein) and illustrates that ARD can be reduced under field conditions in a subtropical–highland climate.

By P. J. Rua

The Piedras Verdes copper mine is a new run-of-mine (ROM), heap leach, solvent-extraction/electrowinning (SX-EW) operation located 21 km (13 miles) north-northwest of the town of Alamos in the state of Sonora, Mexico. The Piedras Verdes copper mine is wholly owned by Frontera Copper Corp. (FCC), a Canadian corporation, through its 100 percent beneficial interest in Cobre del Mayo S.A. de C.V. (CDM), a Mexican registered company. The January 2008, minable reserves were estimated to be 193.6 Mt (213 million st) at a grade of 0.36 percent copper. The overall recovery of total copper was estimated to be 61.9 percent. The property has an additional 17-year life and is designed to produce 31.7 kt/a (70 million lbs/year) of cathode copper. Construction commenced in early October 2005. The first copper cathode was produced 12 months later at a total capital cost of $100 million. Elevations at the site range from 150 to 300 m (490 to 985 ft) above sea level. The area has excellent infra-structure in the form of towns, power, water, roads, rail, airfield and access to the deepwater port of Guaymas (Fig. 1). The surrounding area is also famous for its numerous polymetallic (lead, zinc, copper, silver and gold) epithermal veins. Some of these were mined for more than 200 years and provided the wealth on which the town of Alamos was built. The original village of Piedras Verdes was located in the area of the proposed openpit mine and, consequently, it was necessary to construct a new townsite 6 km (3.7 miles) to the south before project development could commence. The new town site (Fig. 2), complete with power and water supplies, roads, sewer system, schools, clinic and recreational facilities, was completed and occupied by 49 families in September 2005. CDM received its remaining permits from the Mexican environmental authorities on Sept. 20, 2005. This enabled the company to proceed with full-scale development. CDM owns or controls 27 mining concessions covering the resource. Surface rights to the Piedras Verdes project were controlled by four Ejidos (communal agrarian and/or ranching societies) and five individual landowners. CDM has acquired all surface rights necessary for its mining operations and associated facilities either through outright purchase or long term lease agreements.

Jan 1, 2008

By Paul D. Tomlingson

During the next several months, SME’s E-Newsletter will feature 15 articles on maintenance management. The articles may be read online or downloaded and distributed within your organization. They will address maintenance management topics, offer guidelines to mining managers and provide techniques that the maintenance manager can use. The articles will stress equipment management, a strategy that the mining industry has accepted as a modern replacement for outdated maintenance practices. Equipment management is the mutually supportive interaction of all mine departments as they establish equipment needs, procure equipment, test, commission, operate, maintain, modify and eventually replace equipment. The successful application of equipment management principles can quickly and reliably produce cost reduction and performance improvement results while providing a dependable way of sustaining them. Equipment management embraces modern management techniques. These include reliability-centered maintenance, life-cycle costing, capital performance, the effective use of information and productive organizational models.

Jan 1, 2003

By Bryan Ulrich

Rroundtable 2009, a Knight Piésold and Co.-hosted roundtable discussion on mine closure and cover design was held at the Red Lion Inn and Casino in Elko, NV on Feb. 12, 2009. Knight Piésold?s Bryan Ulrich and Steve Boyce, as well as Knight Piésold representatives Cynthia Parnow and Corey Conrad from Denver, CO, and Rick Frechette from the Tucson, AZ office were on hand to help facilitate the discussion. The meeting played host to approximately three-dozen attendees from four states. Attendees included personnel from seven mining properties and attendees from corporate offices. The majority of attendees were people directly involved with environmental work on a day-to-day basis. Other attendees were project managers whose jobs involve some level of environmental focus. The purpose of Roundtable 2009 was to exchange ideas and information pertaining to mine closure and cover design associated with almost any aspect of a mining operation. This type of forum provides a less inhibited format for discussion, when compared with traditional conferences and symposia. In the roundtable format, lively discussions are encouraged. This discussion was the fourth in the series of Elko Roundtable events. Previous roundtables pertained to heap leach pad design, construction and operation; design, construction and operation of tailings storage facilities and site-wide water considerations. The initial subtopics for Roundtable 2009 included:

Jan 1, 2009