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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 T. J. Batchler

Deformable materials are sometimes added to ventilation stopping constructions to prevent damage caused by convergence in coal mines. However, adding deformable materials can significantly reduce the capacity of a stopping to resist transverse loading. As part of its mining health and safety program, the National Institute for Occupational Safety and Health (NIOSH) has conducted research on the effect of various materials with different deformation properties on the transverse loading capability of a stopping wall. Based on a three-point hinge method of failure, a half-wall method of testing in the NIOSH Mine Roof Simulator was used to simulate full-scale wall behavior. This simulated the fracture initiation and eventual failure of the stoppings from transverse loading. The impact of the modulus of elasticity of various deformable materials was examined in this study. A polystyrene foam block with a low modulus of elasticity, which is commonly used as a deformable material, was shown to degrade the transverse load capacity of the stopping by as much 95%. Other materials with higher modulus of elasticity preserved more of the transverse load capacity of the stopping, but were not able to absorb as much convergence. This paper presents the results of a parametric study that quantifies the impact of various deformable materials in block stopping construction under transverse load conditions. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By R. J. Sweigard, C. T. Justice, T. Beckham, E. D. Thompson, T. C. Hopkins

Fine coal refuse is often pumped, as slurry, into surface impoundments as a means of permanent disposal. As the available volume is filled, the height of the embankments are frequently increased. Many times the additional embankment material is placed upon consolidated fine coal refuse. There has been some concern about the long-term effect of consolidation of this material at or above the liquid limit upon its shear strength. A laboratory investigation was performed using three different types of fine coal sluny taken from Central Appalachian coal preparation plants. The refuse was consolidated in 10-foot plexiglass columns under incremental amounts of surcharge loading. The incremental loads were designed to simulate the effect of increasing the height of a refuse embankment on top of the consolidating coal slurry. After the refuse in the columns had consolidated for several months, the columns were cut apart and triaxial tests were performed on both the consolidated material and unconsolidated material for comparison of their shear strength parameters.

Feb 24, 1997

By J. Donovan Jacobs

Many improvements in the art of underground excavation have appeared during the past two decades. These improvements have been both in methods and in machinery and have resulted in more economical construction of today's tunnels. In the realm of machines, the developments of continuous boring heads for either soft ground or rock, random arm excavators and the sliding tunnel floor (Magic Carpet) have each made contributions toward more rapid tunneling. CONTINUITY OF ADVANCE Tunnel boring machines are often referred to as "continuous excavators". Continuous advance (without cyclical interruptions) has not been achieved, however, in any of the machines now in use. In most rotary-head tunnelers the thrust needed to make the cutters bite into the face is obtained from hydraulic cylinders reacting against anchoring devices held stationary by pads which grip against the sides of the tunnel. With this system the forward motion of the cutting head is continuous only until the propelling cylinders have reached their limit of extension. At this point the grippers must be released, moved forward and reset before a new cycle of advance can be begun. Some machines are built to obtain their propelling thrust from hydraulic cylinders pushing backward against newly-installed rings of tunnel support. This is the customary method for propulsion of shields. With it, each cyclical advance or "shove" must await the erection of a new ring of supports. Faster tunnel driving

Jan 1, 1974

By Barton J. Suchomel

Introduction Despite perennial economic turbulence, Argentina continues to push ahead with efforts to develop its fledgling hardrock mining industry. The country lacks the infrastructure and mining history of neighboring Chile, but contains vast areas of great resource potential. The eastern slope of the Andean Cordillera in west-northwest Argentina is a relatively little-explored region offering geology highly conducive to the occurrence of base and precious metals deposits. Past exploration has concentrated on locating and evaluating porphyry copper-molybdenum (Cu-Mo) type occurrences. Comparatively little attention has been given to precious metals potential. An interesting and important group of base and precious metals prospects in northwestern Argentina occurs within and adjacent to the Upper Miocene Farallon Negro volcanic complex in Catamarca province. The volcanic complex contains numerous base and precious metals vein occurrences, high gold porphyry copper prospects, and possible disseminated gold targets that have attracted relatively minor attention in the past. Various geologic aspects of the region have been reported by several workers (Llambias, 1970, 1972; Caelles et al, 1971; and Sillitoe, 1973). Regional geology The Farallon Negro volcanic complex is located within the Sierras Pampeanas morphostructural province about 200 km (125 miles) east of the main Andean Cordillera (Fig. 1). The Sierras Pampeanas is characterized by north-south-trending basin and range topography that developed during the Miocene and Pliocene. Uplifted blocks are composed mainly of lower Paleozoic metasediments and granitoid plutonic rocks unconformably overlain by Tertiary redbeds and minor carbonates. A consistent landward migration of volcanic and intrusive ac¬tivity occurred in this region of the Andes from the early Mesozoic through the mid-Tertiary. An eastward extension of magmatism during the Miocene and Pliocene resulted in the formation of the Farallon Negro volcanic center. Volcanism at Farallon Negro ini-

Jan 8, 1988

By G. Bulut

The recovery of copper and cobalt from ancient copper slags from the Küre region of Turkey was investigated. A fayalitic-type of ancient copper slag containing 1.24% Cu, 0.53% Co and 53.16% Fe were subjected to an experimental study. Two different routes were followed to recover the metal values. The first route was roasting the slag with pyrite followed by leaching. The second route was flotation of the slags, roasting of the flotation tailings with pyrite and leaching. The second route was found to be suitable for the treatment of the copper slag studied. In the flotation step, a copper concentrate containing approximately 11% Cu was produced with a 77% recovery while 93% of the cobalt stayed in the tailings. In the roasting experiments, the effects of roasting time, pyrite: slag ratio and roasting temperature on the dissolution efficiencies of Cu and Co were investigated, and the optimum conditions were determined. In the tests, 87% of the cobalt dissolution was observed after one hour of roasting at 500°C with a pyrite: slag ratio of 3:1. The copper dissolution in the tests was 31%. Based on the results of this study, a process flowsheet is proposed for the evaluation of these slags.

Jan 1, 2007

By A. Yu. Lein, V. V. Maslennikov, S. P. Maslennikova, I. Y. u. Melekestseva, Yu. A. Bogdanov

Tellurium is a high-tech and also toxic element. This element shows sufficient contents in Fe-Mn crusts and nodules in the modern ocean to be involved in future industrial processes [Hein et al., 2003]. Tellurium minerals and contents are not well recorded in modern and ancient black smoker systems. Tellurides are rarely found in sulfides from the modern oceans [Iizasa et al. 1992; Maslennikov et al., 2010]. The previous common opinion that tellurium is scarce in active seafloor hydrothermal systems can be revised due to the recent discovery of abundant tellurides in chimneys from Brothers Volcano vent site [Berkenbosch et al., 2012]. We found abundant tellurobismuthite, hessite, and native tellurium in chimneys from Su Su Knoll vents sites (West Pacific). So, tellurides can be found in some chimneys but absent in others. The causes of this are poorly understood. These conflicting data create numerous questions and require an explanation. The problem can be resolved by research at different scales including analysis of relevant genetic features of host sequences, systematic textural and paragenetic studies of different types of chimneys, and their rare mineral assemblages. Paragenetic models, compositional analyses and ranges of tellurium-bearing minerals and the physicochemical interpretation of chimney diversity in different types of VMS deposits are the main subjects of our research. The data on tellurides in chimneys from ancient VMS deposits should also be useful to resolve this problem.

Sep 1, 2014

By Ellsworth R. Spencer

An assessment of U.S. western hardrock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hardrock mining machines. Of the operators, 96% had daily noise doses that exceeded the U.S. Mine Safety and Health Administration?s (MSHA) permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214% and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jackleg drill. These results will be used to help prioritize noise control development by NIOSH and other partners.

Jan 3, 2010

By M. Z. A. Bakar

A series of full scale laboratory linear rock cutting tests was carried out with a long bladed single disc cutter (292 mm diameter, 11mm wide constant cross-section blade) on dry and water saturated sandstone blocks using a linear rock cutting machine (LRCM). The muck collected from the cutting tests has been analyzed to establish a link with the specific energy (SE) of the operation. Coarseness index (CI), a non dimensional parameter, has been found to be a useful indicator of the relative efficiency of the cutting operation. An inverse relationship of the form SE = k CI-n is observed between SE and CI with very high CI usually corresponding with the lowest values of SE. The power n of the relationship for both dry and saturated rock tests is much less than the values found in the previous studies using constant cross section disc cutters and is believed to be dependent on the strength of the rock and the cutter type used. Although the average CI is found to be lower for saturated rock than for dry rock, at the same time saturated rock cutting is found to be less energy intensive (in terms of SE) than dry rock cutting. Moderate correlation exists between the production rate or yield and the SE of the cutting operation for both dry and saturated rock, which can provide some useful information about the field production rate discounting the effect of discontinuities in the rock mass.

Jan 1, 2012

By B. Law, M. Menabde, B. Baird

Blasor is a new mine planning tool which is being used in the long and medium-term optimization of multi-open-pit operations throughout BHP Billiton’s Base Metals and bulk commodities portfolio. It is not just a scheduler, nor even only a schedule optimizer—although this function lies at the heart of the tool’s functionality—but a pit development plan optimizer, used from ultimate pit design and process plant capacity sizing right through to mining phase design and optimal panel scheduling. The tool uses a mixed-integer-linear-programming optimization engine to determine when material should be excavated and where it should be sent to optimize discounted operating cash flow over the life of operation. The core software design concept of Blasor is to provide a tool which is intuitive and flexible enough so that a competent mine planner can perform a pit development plan optimization without assistance from optimization specialists. To this end, a generalized graphical user interface has been implemented which allows full configuration of the optimization problem, including the definition of all inputs and constraints, specification of the material flow topology, bin and destination class definitions and full specification of the economic model encompassing prices and costs. This paper describes the capability of Blasor and outlines the design concepts underlying its design philosophy.

Jan 1, 2007

By A. Iannacchione

Longwall mining began within the Pittsburgh coalbed of Pennsylvania (PA) in the early 1970?s. Originally, longwall mine layouts were designed to fit within existing room-and-pillar operations, where panels were limited to that of typical production panels, e.g. a few hundred feet wide by a few thousand feet long. In these early designs, the gate entries were comprised of chain pillars similar to those found along main entry systems or within pillar recovery sections. The modern longwall mine has little in common with their 1970?s predecessors. Today the entire mine layout is designed around the longwall mining method. The longwall panels have grown to well over one thousand feet in width with lengths now measured in miles. In addition, development pillar sizes and shapes are matched to specific performance requirements.

Feb 27, 2013

By Charles S. Robinson

INTRODUCTION Geology, the science of the earth, is the fundamental science in the construction of a tunnel. The approximate site of a tunnel is determined by its purpose. The geology of the tunnel site will determine the cost--or feasibility of a tunnel--the specific alignment to accomplish the purpose of the tunnel, the design of the tunnel (within the limits of the purpose of the tunnel), and the methods of construction. The more accurately the geology of a proposed tunnel can be depicted, the more accurately can the cost of a tunnel be estimated. The factors that should be defined for tunnel design and construction are the physical characteristics of the material in which the tunnel is to be constructed. The physical characteristics of the material are determined by the genesis of the material, and subsequent geologic processes that have affected the material. The geologic materials in which tunnels are constructed can be broadly classified as unconsolidated and consolidated. The unconsolidated materials include chiefly deposits of recent geologic time that occur near the surface. Because these deposits occur near the surface, and tunnels constructed in them will be at shallow depth, methods of physical exploration such as geophysical methods, trenching, and drilling will give more data at relatively low cost--therefore the physical exploration is generally, or should be, quite extensive--and the

Jan 1, 1997

By Mohammad Djavid

The one-pass tunneling pipe jacking method has often been the most schedule and cost efficient method for the pipe line installation. The main challenges in jacking pipes larger than 108 inches and for longer runs are: transportation and logistics, requiring high jacking forces, keeping line and grades, control of ground surface settlement, providing adequate external lubrication, and the potential of damaging the joints and pipe spigots. In recent years, 144" diameter pipes have been jacked for short runs of up to only 300 feet. In this article design and construction of installation of up to 1,000 linear feet run of 144-inch internal diameter, reinforced concrete pipes without intermediate jacking station in Chicago O?Hare International Airport are discussed. The article also presents discussions regarding the subsurface saturated silt formation, shallow cover, dewatering, jacking and receiving shafts, jacking forces, lubrication and settlement data.

Jan 1, 2008

It is crucial to reestablish a domestic rare earths minerals production industry to help secure the Nation's clean energy future, reduce the U.S. vulnerability to material shortages related to national defense, and to maintain our global technical and economic competitiveness. Given that the Chinese dominance of the rare earths market has adversely impacted supply stability and endangers the United States and its allies' assured access to key materials, rare earths should qualify as materials either strategic or critical to national security. Further, the U.S. government should facilitate the reintroduction of a globally competitive rare earth industry in the U.S. Realization of this objective requires: ? Developing domestic processing capability so that the U.S. is not primarily dependent on China as a source of rare earth ore, and almost exclusively dependent of China for processing of the ores. ? Providing a mechanism where access to Federal lands for rare earth exploration and extraction is possible, and ? Training engineers to design and operate rare earth ore processing facilities

Jan 1, 2011

By S. Dessureault, Z. Gavelan

As globalization continues, sustainability and social responsibility has become essential in foreign mining investment. However this global trend and the increasing acceptability toward the globalization process, viability and sustainability are not always achieved. Viability and sustainability of mineral projects is dependant on the social and political environment of the region where the mining venture is located and is based on the interaction between the mining entrepreneurs, national-local government representatives, communities, grass-roots groups and independent civil organizations. These are the organizations, which play the acting roles on the viability of mining projects and are the main source of socio-political risks for the project. Throughout the decision-making process to invest in a mineral project, socio-political risks are quantified using a set of measurable variables. Nevertheless, these risk measures should be dependent on specific industries. Two mineral projects, even in the same mining district, may have significantly different political risk profiles based on their own socio-political variables. This paper describes a methodology that takes into account local social and political variables in defining a project-specific’s political risk profile. This contrasts with more typical political risk measures that focus on the country’s overall risk profile. Mining operations must operate on a local scale necessitating the development measure that considers more local variables.

Jan 1, 2004

By C. Frenzel, N. Blechschmidt

"INTRODUCTION There is no doubt about the time and effort companies put in establishing and maintaining their equipment. However, the question about how these companies can map the benefits comes up. Neither do they have the tools to quantify the benefit of their action, nor do they have the tools to know the actual quality of their current maintenance system. The resources used in the process seem futile to observers. It seems impossible to trace improvements and to get information about the impact of actions in retrospect. Improvements in maintenance performance cannot be recognised by management or shareholders. Thus the necessity for measuring the performance of maintenance systems is given. In this paper ConMoto is systematically showing the strengths and weaknesses of many companies' maintenance management and is providing field-tested proven design elements for measuring maintenance systems and implementing Value Oriented Maintenance. Considering only business assets in production facilities and related machinery out of all investment goods in Europe, you reach a value of around 9.7 trillion euros in 2008. In Germany alone the equipment replacement value amounted to about 1.9 trillion euros [8,10,11,13]. If you calculate a cross sector maintenance costs rate of 4.8 % (corresponding to the average value identified in this study), direct maintenance costs in European production locations add up to over 450 billion euros per year [3]. These figures speak for themselves. Yet maintenance is not only of enormous significance for European enterprises. Our experiences show that maintenance and asset management, particularly sustainability issues, are also increasingly moving to the forefront in the BRIC states, in the Middle East and in many emerging countries. First of all, in order to meet the resulting high quality and cost related requirements of maintenance systems, a comprehensive overview of the issue is needed. This overview is provided by a detailed analysis of 83 companies and production plants from various sectors – with amazing results. SIGNIFICANCE OF MAINTENANCE Current studies show the high financial significance of maintenance and asset management. According to the market study in the Asset Manager [9], in industrialised countries about 10 to 15 per cent of the labour force are employed in maintenance and facility management tasks. In Europe about 40 to50 million people are directly and indirectly involved in retaining the value of machinery, plants, buildings, transport systems and infrastructure facilities. A glance at the costs side also demonstrates the great relevance of maintenance. EU-wide annual direct maintenance costs amount to a total of more than 1,500 billion euros. In Germany alone they are about 250 billion euros. This impressive total is considerably exceeded by indirect maintenance costs caused by technical failures. Indirect costs are estimated to be five times higher (Figure 1). [7,12,14]"

Jan 1, 2018

By S. M. Carpenter

In response to the FY2008 Consolidated Appropriations Act (H.R. 2764; Public Law 110?161), the United States Environmental Protection Agency (USEPA) issued the final Mandatory Reporting of Greenhouse Gases Rule (MRR). The rule, signed by the USEPA Administrator, Lisa Jackson, on September 22, 2009, requires reporting of greenhouse gas (GHG) emissions from large sources and suppliers in the United States, and is intended to collect accurate and timely emissions data to inform future policy decisions. The MRR will go into effect on January 1, 2010, and a report of the total emissions for calendar year 2010 will be due to the USEPA by March 31, 2011. Under the final MRR, suppliers of fossil fuels or industrial greenhouse gases, manufacturers of vehicles and engines, and certain facilities that emit 25,000 metric tons or more per year of GHG emissions are required to submit annual reports to the USEPA. The gases covered by the rule are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC), sulfur hexafluoride (SF6), and other fluorinated gases as outlined in Table A-1 of Subpart A of the MRR, which is also provided in Appendix A of this report.

Jan 1, 2011

By Akihiro Higashide, Roy H. Patten

The DOT Tunneling method combines two conventional earth pressure balance shield machines in an overlapping cylindrical arrangement. The method allows two tunnels to be driven simultaneously with mini¬mum cross sectional area. Two full size trials, one configured horizontally and one vertically stacked, were successfully completed employing the DOT method. The method was then utilized for the new transportation system. The goggle-shaped DOT machine, 9.36 m high by 15.86 m wide, is the largest earth pressure balance shield machine in the world. This paper includes a general description of the DOT tunneling method as well as a history of its development.

Jan 1, 1995

By R. Mier

The metals and minerals mining industry has evolved dramatically from the earliest objects ever made out of native copper circa 9,000 BC to the modern developments we see today. To better appreciate past developments and to get a sense of where the industry is heading, a brief overview of mayor industry highlights over the last 100 years will be presented, followed by a discussion on potential global scenarios and by a review on mayor industry trends.

Feb 27, 2013

By Shaoxian Song, Ling Xia, Hongqiang Li, Yubiao Li, Yunliang Zhao, Shaobing Xie

Since human daily demands for fresh water have been increased significantly, the supply of fresh water for the mining industry, especially froth flotation, should be considerably reduced. In addition, stricter environmental standards have been implemented in many countries to reduce the risks due to the disposal of wastewater, many flotation operators have to seek more efficient ways to utilize the limited fresh water sources. Recycling water with high concentrations of impurities is a normal strategy for most of the mineral processing plants; however, water quality should be carefully considered to guarantee a smooth flotation process. Recently, the application of seawater in flotation has attracted much attention due to its availability and abundance rather than fresh water. However, the influencing mechanisms due to the application of seawater in flotation have not been fully understood especially the reactions between mineral particles and bubbles in the presence of high concentrations of cations and anions. This would impede the application of alternatives to fresh water in the flotation. Therefore, this paper reviews the current water sources and the technologies for water recycling in the flotation process. Specifically, the life cycle of water in flotation was proposed. In addition, the strategies including high pulp density flotation as well as the most promising alternatives to fresh water have been discussed in details, with the related mechanisms being demonstrated.