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By William R. Yernberg

The Society of Economic Geologists (SEG) held its biennial conference May 14 through 16, 2006, in Keystone, CO. SEG is an international organization with about 3,500 individual members with interests in economic geology. The 2006 SEG conference theme was “Wealth creation in the minerals industry — integrating science, business and education.” The conference exceeded expectations with 705 participants, including 102 students, from 44 countries. The conference featured 30 oral presentations, 24 professional posters and more than 70 student posters. The conference also included a trade show with 50 vendors, numerous field trips, workshops and social activities.

Jan 1, 2006

By Jeffrey Mitsopoulos

King County?s (KC) Brightwater Conveyance Project in Seattle, Washington involves the construction of approximately 21 kilometers (13 miles) of bored tunnel, in three contracts, with four TBM?s which produce large amounts of real-time digital mining data. To facilitate the management of TBM data with a single interface and assist in project Quality Assurance, KC?s Construction Manager (Jacobs Engineering) recommended the use of the software TPC (Tunneling Process Control), developed by Babendererde Engineers GmbH. The paper demonstrates how TPC was used for oversight, analysis and QA on a complex tunneling project and how contemporaneous review and management of data results in a better understanding of TBM performance than can be obtained by retrospective analysis of data.

By Gary Almeraris, Vincent Jr Tirolo

Traditionally, “Means and Methods” were the sole responsibility of Contractors. However, because of a number of litigious projects in the 1970s, Owners and their Engineers began including Suggested Methods of Construction (SMC) in Contract Drawings. By the late 1990s these SMCs were becoming baseline “Means and Methods” with Contractor recommended changes often considered as Value Engineering proposals. By 2004, the word “Suggested” was sometimes changed to “Prescriptive.” Owners are also purchasing TBMs and other mining equipment for Contractors prior to bid. Is limiting the contracting community’s innovation in developing their own “Means and Methods” and selecting their own equipment in the best interests of the Owner? Does it reduce the Owner’s, Engineer’s or the Contractor’s risk? Are claims reduced and finally what is the impact on the bid? A questionnaire was sent to more than fifty senior engineering field and management personnel representing more than 30 heavy construction companies to ask their opinion on these questions.

Jan 1, 2005

By N. Arbiter, C. C. Harris

The economic advantages of large diameter ball mills can be compromised by unexpected capacity limiting conditions. These arise because media rotational flow to ore axial flow ratios, and the number of mill revolutions that ore is subjected to during residence, are both inversely proportional to mill diameter. Because of this, mixing efficiency and grinding kinetics may decrease and become capacity limiting when mill diameters reach a critical range. There are two possible scale-up problems involved in the design and use of mineral processing machinery: • Selecting the size and operating conditions for available larger equipment, to insure that operating results will match those obtained with smaller units; or •Extending the size ranges of equipment beyond existing limits. Previous research at Columbia University into flotation machine hydrodynamics has demonstrated the importance in scale-up of internal flow relationships; these perform a similar role in grinding (Arbiter and Harris, 1980).

Jan 1, 1982

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once an analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at its power plants. A quality assurance program can also help a mine deliver a consistent product to a utility's power plants. The importance of accuracy, timeliness and consistency are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

By Andrea Brickey, JUDITH BUABA, RICHARD AMOAKO

The global mining industry has recorded significant declines in accident and injury rates attributed to the advancement in technology, increased enforcement, and safety consciousness. A goal of the mining industry is to achieve zero injury and occupational illness on all mine sites, prompting increased research into ways to further reduce mine accidents. A machine learning technique known as multiclass logistic regression is applied on a 10-year injury dataset from the Mine Safety and Health Administration (MSHA) to determine a miner’s susceptibility to a class of injury and to help identify significant risk factors associated with different classes of injury. The data is aggregated based on injury classification to provide statistically relevant results. The analysis identifies specific risk factors that influence a mine worker’s susceptibility to a given class of injury, i.e., non-fatal with no days lost or restricted activity, non-fatal with days lost and/or days of restricted work activity, and fatal and total permanent or partial permanent disability. These factors include miner’s age, mine type (coal vs. non-coal), experience on the current job (years), shift start time, employment type (operator vs. contractor), mining district, and type of accident. The results of the analysis indicate that a miner’s experience on the job, i.e., the number of years worked in a current job, is a significant risk to injury occurrence, even for those with decades of total mining experience. We further show the differences and similarities between the surface and underground mine incidents.

Nov 3, 2020

By V. Arslan

The primary advantage of using oxalic acid is in the formation during leaching of soluble complexes that are both photo-chemically and microbiologically degradable. In this study, chemical leaching and bioleaching methods were used for quartz sand. Using the ANOVA-Yates test technique, the effects of solids rate, temperature and oxalic acid rate were investigated using chemical leaching experiments. Solids rate and temperature were effective parameters on the chemical leaching. After the tests, the removal of Fe2O3 increased to 97.02%. Finally, the iron content decreased from 0.315% Fe2O3 to 0.0094% Fe2O3 in the leached quartz sand. The effect of pulp density was investigated on the bioleaching experiments. The bioleaching of iron oxides by Aspergillus niger resulted in removal of 47.70% of the total iron in the quartz sand, and suggested that this strain has not a good ability to remove iron impurities from quartz sand in comparison with chemical leaching. The iron content decreased from 0.315% Fe2O3 to 0.164% Fe2O3 in the bioleached quartz sand.

Jan 1, 2009

By Raja V. Ramani

Discussion in this section of the Handbook is limited to the working environment of miners, the mine workers themselves, and the machines used in mining (Fig. 11.0.1). The contents emphasize personnel health and safety aspects and engineering design and control practices to ensure a productive health and safety environment. Reference is to the health and safety of the individual miners as well as to the safety of the working environment. This Handbook also contains references to health and safety regulations in Chapter 3.2 and environmental protection in Chapters 3.4 and 7.3.

Jan 1, 2008

In bump-prone coal mines, roof and rib support is subject to dynamic as well as static loading. Although less frequently encountered, the dynamic loading component can result in violent coal expulsions into openings seriously threatening the safety of workers. Dynamic support systems that have been increasingly implemented in many deep hard rock mines for dynamic failure containment have not yet found their adaptation to deep coal mines at desired levels. This paper examines the potential use of some of these dynamic support systems in deep coal mining, particularly in the western United States. Fundamental principles of dynamic loading are reviewed in the context of their application to dynamic failure mechanisms in coal mines. Potential benefits and applicability of the suitable hard rock dynamic support systems are discussed in relation to coal bump mitigation. The resulting insight provides a starting point for development of dynamic support elements for bump prone conditions in deep coal mines.

Jan 1, 2009

By S. Devasahayam

Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized pyrite/acid production with depth in black coal mine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.

Jan 1, 2007

By J. W. Jamieson, J. Escartin, A. Steinführer

Evidence of hydrothermal activity on two Mid-Atlantic Ridge oceanic core complexes (OCCs), at 13º30’N (the Semyenov 1 through 5 fields) and 13º20’N (the Irinovskoe field) (Fig. 1) were studied using CTD casts, dredges, TV-grabs and SP surveys during previous research cruises to these sites (Cherkashev et al., 2013, McLeod et al., 2009). In late 2013, the Semyenov and Irinovskoe fields were revisited, this time with an autonomous underwater vehicle (AUV) and a remotely-operated vehicle (ROV) during the ODEMAR (Oceanic Detachments at the Mid-Atlantic Ridge) cruise on the French research vessel "Pourqoui Pas ?". Here we present the first visual surveys and direct sampling of these vent sites. High-resolution (~2 m) bathymetry of the 13º30’N and 13º20’N OCCs and their associated vent fields was collected during 4 and 5 AUV dives, respectively, using the GEOMAR AUV "ABYSS" (Fig. 1). These surveys were flown between 70 m and 100 m above the seafloor, typically at a constant height to reduce vehicle movement. The AUV was equipped with Eh, turbidity, and temperature sensors in order to detect active hydrothermal venting. Over twenty ROV dives with the ROV "VICTOR 6000" allowed for the visual exploration of the OCCs and collection of 59 hydrothermal rock samples from the vent fields. As a result of these exploration activities, the first robust estimates of the size of the deposits, and the geologic controls on sulfide accumulation at these sites can be determined.

Sep 1, 2014

By V. L. Andrade, K. L. C. Goncalves, N. A. Santos

This paper describes results obtained in a test program performed with new equipment, called Mini Pilot Plant, manufactured by Canadian Process Technologies. This equipment was acquired by CVRD aiming at testing flotation circuits, in a continuous closed configuration, with samples obtained from drill cores. Success of this goal would allow CVRD to establish the metallurgical performance of mineral deposits with more confidence in comparison to Locked Cycle Tests (LCT). This paper discusses the importance of assessing the ore variability and compares results obtained in LCTs and Mini Pilot Plant. Results suggest that more reliable data is obtained in MPP test.

Jan 1, 2002

By Fulvio Tonon

And Rabcewicz said ?tunnels should be driven full face whenever possible.? ADECO, which stands for ?Analysis of Controlled Deformations in tunnels,? now allows us to fulfll Rabcewicz?s dream in any stress-strain condition. In order to achieve that dream and its consequent control over cost and schedule, however, NATM must be abandoned for the ADECO. The paper presents the basic concepts in the ADECO approach to design, construction and monitoring of tunnels together with some case histories, including: full face excavation for Cassia tunnel (width of 22 m, height of 14 m) in sands and silts under 5 m cover below an archeological area in Rome, Italy; Tartaguille tunnel (face area > 100 m2) advanced full face in highly swelling and squeezing ground under 100 m cover where NATM led to catastrophic failure, France; and 80 km of tunnels (face area > 100 m2) advanced full face in highly squeezing/swelling ground under 500 m cover for the high-speed railway line between Bologne and Florence, Italy (turnkey contract).

By Thomas Kuhn, Carsten Ruehlemann, Christina Heller, Anna Wegorzewski

The commercial extraction of metals from manganese nodules on an industrial scale requires more than 50% of the investment necessary to realize manganese nodule mining. This is mainly due to the fact that a completely new metallurgical processing scheme for the extraction of both base metals (Ni, Cu, Co) and high-tech metals (Mo, Li, Ga) has to be developed and upgraded to industrial scale. There are a number of conventional processing technologies that combine hydro- and pyro-metallurgical approaches such as the INCO and CUPRION processes which have been developed in the 1970s and 1980s. Today, new approaches based on selective leaching with chelating agents and bioleaching try to minimize energy consumption and waste production. All of these extraction methods require knowledge how the metals are structurally bound in the manganese oxides. In this contribution we will review the current knowledge about the mineralogy of iron and manganese minerals in the different marine oxide deposits, present our results, and discuss the possible consequences for metal extraction.

Sep 1, 2014

By W. Lin, M. J. McPherson

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Feb 24, 1997

By Thomas L. Richardson, David R. Chapman, Gary W. Gilbert

The two contracts of the Big Walnut Augmentation/Rickenbacker Interceptor(BWARI) sewer project for the City of Columbus, Ohio total nearly 35,000 feet of 14and 12-foot diameter tunnel. EPB TBMs will install precast concrete segmental lining through difficult glacial soils ranging from clean granular to hard till with high groundwater and boulders, crossing roads, railroads, and a large stream. Construction of 12 shafts and a large Interconnect Structure involving major ground stabilization work is required. The paper will review design of major project elements and present an update on construction progress.

Jan 1, 2005

By Arthur Darby

The city of Kuala Lumpur was founded in 1857 by miners seeking tin near the confluence of the Klang and Gombak rivers. The rapid development of the city and surrounding area since independence has led to more rapid runoff during rainstorms and to gradual canalisation of the rivers with some restricted sections. The outcome has been more frequent and more severe floods (Abdullah 2006). At the same time the centre of Kuala Lumpur has become a modern inter-national city with tall office buildings, hotels, and shopping centres connected by a network of wide roads and commuter rail systems. With these the cost of dislocation during floods has risen as has the cost of making good damage afterwards. The Government of Malaysia considered these consequences unacceptable and sought ideas from the private sector for a solution. Potential solutions consisted of variations on the themes of bypassing the city centre with a flood relief tunnel or of providing off channel storage or a combination of both. Since under Malaysian law a tunnel cannot be constructed under private property unless this is first purchased or agreement reached with the owner, it was necessary for most of the tunnel alignment to run below existing heavily congested roads. After considering these facts Gamuda Berhad and MMC Berhad, two leading Malaysian development and construction companies, decided to propose to Government an innovative solution in which the tunnel would be used to carry road traffic except during floods.

Jan 1, 2008

By William R. Yernberg

The combined 75th Annual Minnesota Section of SME meeting and 63rd Annual University of Minnesota Mining Symposium was held April 9 and 10, 2002, in Duluth, MN. This year’s theme was “Keys to the Future: Imagination, Innovation and Technology.” The meeting consisted of plenary and technical sessions and a special General Manager’s Session. The technical paper presentations included concurrent mining and mineral processing sessions. In the General Manager’s Session, representatives from the region’s taconite operations presented the current status, concerns and future plans for each of their operations.

Jan 1, 2002

By W. A. Vine

Next year, in 1964, Butte will celebrate its Centennial. It was in May, 1864, that the first recorded mining activity took place. During that summer, several rich placers were found on Silver Bow Creek and its tributaries, and a gold rush followed. As placer mining proceeded in the creek beds, the quartz lodes on the hillsides were located and the veins were prospected. Mining in Butte entered its second phase when the rich silver mines, the Alice, Moulton, and Lexington, were opened. The silver boom lasted until the decline in the price of silver in the early 1890's forced the closure of many of the mines. An indication of the beginning of the copper mining era in Butte was in 1866 when it was noticed that green copper carbonate discolored some of the, lode material. It was not until ten years later, however, that the Anaconda and St. Lawrence claims were located by Michael and Ed Hickey. The claims were sold in 1880 to Marcus Daly and in 1881, Daly obtained financing and organized the Anaconda Silver Mining Company to exploit the vein The silver venture was a failure because of the predominance of copper which diluted the bullion to only 400 fine.

Jan 1, 1963