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By G. Pan

A geostatistical approach is proposed for the design of infill drilling programs. The method is consisted of three major steps: developing geological favorability models, delineating mineralization and ore envelopes, and classifying reserves or resources. Geological modeling aims at developing favorable geological zones in which drilling is designed. Modeling mineralization and ore envelopes establishes criteria on potential blocks to be drilled. Top target blocks should be those included within ore envelopes. The framework of resource categories includes five types: probable reserves, indicated reserves, indicated resources, possible resources, and barren. Indicated reserves or resources are the top priority to be drilled for the definition of minable reserves. Possible resources may be considered as targets for further exploration. The algorithms involved in the analysis include indicator favorablity analysis, ordinary kriging, and indicator kriging. A case study presented here involves a gold deposit of Carlin type. The deposit was delineated by a sparse drilling program with 230 feet of average spacing. The infill drilling program designed by the new method suggests a significant reduction on the number of holes from a regular-grid infill drilling pattern.

Jan 1, 1995

By D. J. Barratt

What is meant by "Minimizing Risk"? This paper explores some of the factors encountered in plant design which can affect the success of a mineral processing plant in terms of its planned output, quality of product and recovery. Any deficiency in either one of these objectives means lost revenue at the start of a project and reduced present value for the mine life. Time is money. Related factors such as project conception, feasibility studies, capital cost and operating cost estimation and mining studies have been covered in a recent paper (1) from which material for this paper has been drawn. What follows is a discussion of the principal factors which can influence the success of a project with particular emphasis placed on processing concepts.

Jan 1, 1983

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

Réseau Express Métropolitain (REM) is the new Light Rail Transit (LRT) network of Montreal, Canada. This new LRT network uses a century-old Mont Royal Tunnel (MRT) to connect Downtown Montreal to the north side of the Island of Montreal by passing through Mount Royal Mountain. This railway double track horseshoe tunnel is approximately 5 km (3.1 mi.) long, 8.8 m (29 ft.) wide and 5.5 m (18 ft.) high, with a constant 0.6% grade. Due to different geological characteristics of the surrounding ground, varied from hard rock to soft soil, different cross sections and excavation methods were adopted for construction of this tunnel. In order to use MRT in the modern transit system, the tunnel needed to be inspected, rehabilitated and be compliant to the recent safety standards. This paper presents a summary of history and characteristics of the existing tunnel plus the implemented steps to upgrade the tunnel. It includes the details of the structural inspection and rehabilitation methods of the tunnel. Further, this paper summarizes the procedures for the space proong, construction of the separation center wall, and the tunnel enlargement. It also describes parts of complications encountered during the construction and solutions implemented to tackle these issues.

Jun 23, 2024

By F. N. Kissell

U.A. Mine Safety and Health Administration (MSHA) coal dust compliance data sometimes shows high silica levels at roof bolters. However, it is unclear whether this silica normally originates from the bolter itself or from other dust sources upwind of the bolter research studies to answer this question at individual mines have been conducted. However, operational practices vary from mine to mine thus, the information gleaned from any one study cannot be accurately extrapolated to describe silica dust sources in most mines. In this paper, three decades of bolter dust research are reviewed the results showed that, while inadequate maintenance on the bolter dust collection system can result in excessive dust, more likely reasons for high silica levels are inadequate ventilation of the mine entries being bolted and dust traveling downwind from the continuous miner to the bolter. Scrubbers on continuous miners may not be removing as much silica dust as expected. Mining Engineering, 2011, Vol. 63, No. 10, pp. 78-82. Official publication of the Society for Mining, Metallurgy and exploration, Inc.

Jan 1, 2011

By J. Hupka

The limited effectiveness of the original hot water process for recovery of bitumen from certain Utah tar sands containing bitumen of higher viscosity (e.g. Sunnyside, Tar Sand Triangle)1,2 indicated that bitumen viscosity strongly' influences the separation efficiency. In this regard, there should exist a critical value of bitumen viscosity above which the effectiveness of the hot water process decreases significantly. Apparently certain tar sands contain bitumen of such high viscosity that even a digestion temperature of nearly 100°C is insufficient to lower the viscosity below the critical value. In addition it seems that differences in physico-chemical forces which act between sand and bitumen are negligible in comparison to the difference in visco-mechanical forces. Predominantly mechanical forces hold viscous bitumen on the rough surface and in the pores of sand particles, resulting in strong adhesion. This phenomenon is a critical feature in the phase disengagment of oil-wetted domestic tar sands with viscosity control by temperature. Besides increasing the temperature for viscosity control the effectiveness of the original hot water process could be enhanced by control of bitumen viscosity with diluent additions. Strictly speaking this appraoch is the only possibility for heavy bitumen for which the high temperature of digestion does not lower the viscosity sufficiently. As a result of viscosity control by diluent addition the digestion temperature can be lowered which is important from an industrial standpoint. Another important consideration is that effective phase disengagement occurs only when the entire bitumen phase has the same viscosity. This means that some time (penetration time) is necessary for complete and uniform dilution of the bitumen. If the viscosity of bitumen, which is a function of temperature, diluent addition and penetration time, controls the separation efficiency, hot water processing of many different kinds of tar sands should be possible, assuming that the sand phase consists primarily of quartz-type minerals.

Jan 1, 1982

By Reed J. Irvine

One normally does not find sudden and dramatic changes in the investment climate, barring the unexpected outbreak of-wars or revolutions. Asia has seen a fair amount of military action and revolt during the past year, not all of it unexpected There was the fighting in Laos, which resulted in the as yet unconcluded negotiations which will probably lead to the establishment of a neutralist regime. In April of 1961 another revolution occurred in South Korea, and the elected government was replaced by a military dictatorship.. Communist guerrilla activity in South Vietnam was stepped up, and uncertainty about the future of that area increased. Relations between Pakistan and Afghanistan became more strained, and while no fighting has broken out, diplomatic relations between the two countries were broken off. India was both the victim of further incursions of her territory by communist China and the perpetrator of the forcible seizure of territory from Portugal. Indonesia has been making preparations for an armed attack on the Dutch in New Guinea.

Jan 1, 1962

By Albert W. Deurbrouck

The coal reserves in the United States are estimated to be in excess of 300 billion recoverable tons, and current projections of energy requirements indicate our increased dependence upon these reserves. The Department of Energy's Energy Outlook for 1984 projects that coal consumption in the United States will increase from 737 million tons in 1983 to 958 million tons in 1990, and then to 1,110 million tons in 1995 (Table 1). As shown in this table, the future utilization of coal in the United States is closely tied to the electric utility market, a market that consumes about 85% of the coal produced. Be- cause of this dependence on the utility market, the uncertainties of new environmental regulations, particularly those concerning sulfur emissions, could have a significant adverse impact on future coal demands in the United States. SULFUR IN U.S. COALS Most of the Nation's coal reserves contain too much sulfur to be fired directly and meet existing emission control standards. In Table 2, the sulfur contents of the coals of the eastern United States are summarized by sulfur levels according to regions. While the coals of some of the eastern regions are predominantly high in sulfur content, it is important to recognize that large tonnages of coal with relatively lower sulfur content are available in these regions. Furthermore, an often significant portion of the sulfur occurs in the form of iron sulfide (Fes2 or pyrite). Because pyrite occurs as discrete particles of high specific gravity, it can often be removed by simple, inexpensive physical coal beneficiation techniques after being liberated by stage crushing. The potential for physical removal of pyrite by conventional specific gravity processes combined with stage crushing is summarized in Table 3 on a regional basis.

Jan 1, 1986

By Karoly (Charles) Kocsis, Kyle A. Scalise

Understanding the climatic conditions in underground mines is necessary for efficient ventilation design, cost savings, and to ensure the health and safety of mine workers. Large volumes of ventilation and climatic data including air volume, barometric pressure, dry bulb temperature, and relative humidity were collected at active underground precious metal mines in Nevada, which allows for the determination of wet bulb temperature and other key parameters. Through the utilization of neural networks, the wet bulb temperature at the bottom of the intake shafts is predicted, while taking into account the “thermal flywheel effect” (TFE). Wet bulb temperature is one of the most important climatic parameters to model and understand because it significantly affects the work conditions and the cooling capacity of the ventilating air. The accurate prediction of the dry bulb and the wet bulb temperatures at the bottom of intake shafts is critical when assessing the climatic conditions in future underground mines and deciding onwhether a cooling system is needed to assure adequate working conditions throughout themine. By utilizing accurate predictions of wet bulb temperatures and other climatic parameters, mine personnel will be safer as reported by Bluhm et al. (2003), and a more accurate ventilation design can be achieved resulting in major cost savings for underground mines.

Mar 3, 2021

By Shu Fan Chau, Innes Duncan, Harry Asche, Bill Newns

The North Auckland Line (NAL) in Northland, New Zealand, is being upgraded to pass Hi-Cube containers. The line includes many tunnels and bridges which need to be refurbished to improve structural clearances and line capacity. Tunnel 2 along the line, the Makarau Tunnel, has posed special challenges. Opened in 1898, the tunnel suffered multiple collapses during construction and has shown significant distortion during operation. The tunnel has been repaired many times since opening. Successfully enlarging this delicate and distressed structure has involved historical research, advanced analysis and design, and careful construction. The results provide lessons for dealing with brick lined tunnels and poor ground conditions

Jun 13, 2021

By David J. Brown

Extensive deposits of bituminous, subbituminous, and lignite coals occur in the western United States (Figure 1). Over one trillion tons of identified resources have been located and inferred by geologists and more than 200 million tons of western coal are mined annually (1). In the future, production of western coals will increase significantly and approach national production levels of higher-rank eastern coals. Western coals will be utilized in new power plants as a replacement fuel for oil and gas and may be used in advanced technologies such as diesel engines or in direct-fired turbines. Since these applications require low-ash, low-sulfur coals, crushing to fine sizes and significant cleaning to remove minerals and sulfur will be required. Coal cleaning traditionally has been associated with reducing pyrite and other mineral matter from high-rank eastern coals. To date, insignificant quantities of western coals have been cleaned before utilization and limited data on their washability characteristics exist. Because of this lack of data, it is difficult to predict how these coals will react to standard washing techniques.

Jan 1, 1985

By R. W. Wittkopp

The Relief Canyon gold deposit is located approximately twenty- four kilometers east of the town of Lovelock in Northwestern Nevada. At Relief Canyon, the Late Triassic Grass Valley Formation has been thrust over the Late Triassic Natchez Pass Formation. The lower plate Natchez Pass Formation is composed of massive gray dolomitic limestone which is locally silty and sandy. The upper plate Grass Valley Formation is composed of shale, siltstone, argillite and quartzite. Gold mineralization at Relief Canyon occurs along the highly brecciated thrust contact between these two formations. Weak gold mineralization often occurs above the thrust in the Grass Valley Formation, however, most of the ore grade mineralization is present below the thrust in the brecciated Natchez Pass Formation or where the two formations are mixed as a result of movement along the thrust. Several types of gold mineralization have been recognized at Relief Canyon. A large amount of the ore is present as a jasperoid breccia, however, significant amounts of ore occur as a mixed breccia composed of upper plate rock, fresh limestone, clay and jasperoid breccia. Gold ore also occurs in a fresh limestone breccia which contains a large amount of clay. Below masses of jasperoid, jasperoid stringers containing gold extend into the fresh limestone. Gold mineralization at Relief Canyon appears to be truly disseminated and has the typically associated trace elements of arsenic, antimony, mercury and fluorine. The Relief Canyon deposit can be classified as a structurally controlled disseminated gold deposit. Other deposits that fit this classification are the Pinson and Dee gold mines.

Jan 1, 1984

By Abegail Endraca, Allan Sebastian, Andrew Raine, Allan Patdu

The project involves the construction of a new aqueduct tunnel by an Earth Pressure Balance TBM tunnel for the Novaliches-Balara Aqueduct No 4 (NBAQ4) project in Metro Manila. It comprises a 7.3 km long and 3.1 m internal diameter tunnel that can deliver up to 1,000 MLD of raw water and the tunnel passes under urban residential and urban populated areas adjacent to and along Commonwealth Avenue. A new reservoir intake structure was constructed in the La Mesa reservoir by a cofferdam and the TBM breakthrough connected the reservoir to the outlet surge shaft structure and the downstream pipe network system connecting to the Balara Water Treatment Plant. The TBM incorporated a double articulated head configuration to allow tight 80 m radius curves to navigate some of the difficult alignment considerations. The alignment passed very close to some existing foundations for MRT7 and needed to clear several tight curves to remain within government land ownership. The project excavated through the local Guadalupe weak rock formations and there was minimal ground movements observed as a result of the work.

Jun 13, 2023

By Peter Zhang, Daniel Su, Berk Tulu, Bo Hyun Kim, Zoheir Khademian

Over 2,000 shale gas wells have been drilled in the Pittsburgh Seam longwall reserves. As longwall panels are laid out, some of these shale gas wells must be located in longwall chain pillars. With longwall mining on both sides and the constraint of chain pillar size, gas well in chain pillars are subjected to longwall-induced ground movements and stresses, which could induce deformations in gas well casings Casing deformations are associated with several factors such as overburden geology, surface topography, setback distance, and casing construction. Overburden geology is one important factor that largely determines the locations and levels of deformations in gas well casings Previous NIOSH gas well research has found that casing deformations above the coal seam horizon are smaller under deep cover than unde shallow cover and that casing deformations could occur at the coal seam horizon under deep cover. Recent mine-by cases have provided more insights into the locations and amount of longwall-induced casing deformations as well as the potential occurrence of a large casing deformation at the coal seam horizon. This paper presents three recent mine-by cases with shale gas wells in the chain pillars between two adjacent longwall panels under different overburden depths. Casing deformations were measured by multi-finger caliper surveys and predicted with numerical modeling. With the established numerical model, the effect of overburden depth was further analyzed to investigate the potential occurrence of a large casing deformation at the coal seam horizon under deep cover. These mine-by cases not only provide a general demonstration of how overburden depths can affect longwall-induced stresses and deformations but also give a good indication about the level of casing deformations that could occur under different overburden depths. The study concludes that (1) casing deformations reduce with increase of overburden depths at the gas well; (2) a cementing alternative with production casing uncemented is an effective means to eliminate production casing deformations; and (3) large plastic casing deformation could occur in the production casing at the coat seam horizon under deep cover. The experience and knowledge gained from these mine-by cases would help longwall operators and gaza companies to take appropriate measures to minimize the influence of longwall mining in shale gas wells in chain pillars.

Jun 25, 2024

By Edward S. Plotkin, Gary A. Almeraris, Thomas F. Peyton

The lining of the tunnel and shafts for a new section of New York City's- water system required extensive components to produce, deliver and place a continuous tunnel linning. The project placed approximately 153,000 CM (200,000 cy) of concrete for 5,340 M (17,520) of drill and blast 7.3 M (24 ft.) ID tunnel, located at depths of 152 M (500 ft.) to 213 M (700 ft.) . This section of tunnel will be connected to the surface water distribution system via four shafts of varying diameters ranging from 5.8 M (19 ft.) ID to 1.5 M (5 ft.) ID . All work was done beneath the streets of Manhattan under the rigid constraints of the City of New York and the Bureau of Water Supply regulations.

Jan 1, 1987

By H. Vigil Fernandez, G. Peach

The Musaimeer pump station and outfall project located in Doha Qatar, was designed to collect and manage ground and stormwater and then discharge the treated waters offshore. The project constructed a long outfall tunnel using an EPB TBM with segmental lining, each tunnel ring being 1.35 m in length with an internal diameter of 3.7 m.. The diffuser structure was a 6-arm structure, measuring 294m by 40 m connected to a central manifold in turn connected to the TBM constructed tunnel via a riser shaft drilled from an off-shore barge. This technical paper will discuss the planning, methodology and construction practices employed to connect the TBM tunnel to the diffuser structure 10.2 km offshore.

Jun 13, 2023

By P. J. Lafforgue

In 1974- COGEMA (Compagnie Generale des Matieres Nucleaires) of France decided to exploit a uranium deposit discovered several years ago in a Permian formation of Southern France, near the town of Lodeve (Herault). The uranium occurs in black shales with high calcium carbonate content (7-10% CO2) and it was then necessary to use alkaline leaching. A fine grind (60-65% minue 270 mesh) was also necessary to obtain good' uranium recovery. A minimum of fresh water must be added to the alkaline system due to solution recycling. Filtration must be used because cake-washing requires less fresh water than countercurrent decantation.

Jan 1, 1982

By Samuel Frimpong

The preparation of graduate talent for the mining industry is a challenging process, given the multifaceted and complex array of decisions mining engineers make in discharging their responsibilities. As leaders, mining engineers must manage operations, lead project teams, mentor junior engineers, chart the technological directions of companies and deal with several organizations for maintaining the technical and economic feasibility of operations within strategic and tactical framework. Traditionally, the completion of the bachelor of science degree curriculum, with a minimum cumulative grade point average (CGPA), has been used as a graduation measure by Missouri University of Science and Technology (Missouri S&T). Companies have long realized the limitations of the CGPA for recruiting graduates because mining engineering is an applied engineering discipline. Company recruiters have sought to correct the limitations by factoring experience and behaviors into the selection process when recruiting knowledgeable and well-rounded graduates. In this paper, the authors introduce a new metric, which combines the current CGPA (knowledge) with experience and attribute (KEA) metrics to gauge the job readiness of graduating engineers. The KEA metric, also called the job-readiness factor (JRF), is the sum of K (50%), E (30%) and A (20%). The KEA process has been applied to a graduating class in Missouri S&T to demonstrate the value of the new metric system. The results show a fairly positive correlation between CGPA and the KEA metric, with a coefficient of determination of about 70%. Overall, the KEA metric system provides a better picture of the capacity and job readiness of graduates entering the workforce.

Jun 1, 2013

By Ralbern H. Murray

Typical First Year Selling Price Strip Mined Western Sub-Bituminous Coal Based [Fixed Capital (1) $600 MM Construction Loan Interest $100 Working Capital $ 30 Start-up Costs $ 30 Total Capital Requirement $760 MM Annual Costs (First Year) $M/Year Coal (2) 443,550 Operating Costs(3) 53,000 Depreciation(4) 36,500 Interest(5) 45,220 After Tax Profit(6) 34, 200 Federal Income Tax (48% Rate) 31, 570 Gross Revenue Required 245,040 (Less) By-Product Sales (18, 000) Net Revenue Required 227, 040]

Jan 1, 1975

By R. Sellaro, E. Sarver

It has long been understood that extended occupational exposures to respirable mine dusts can lead to chronic lung disease. In underground coal mines, coal workers pneumoconiosis (CWP) and silicosis are major concerns. While many efforts have been made with the aim of understanding the mass-based concentrations and silica contents of respirable dusts under a variety of mining conditions, little research has been completed in characterizing dust at the individual particle level (by composition, size and shape). This study employed scanning electron microscopy with energy dispersive x-ray (SEM-EDX) to analyze dust samples collected from an underground coal mine in Central Appalachia. The results indicated that particle characteristics can vary widely between locations, though many trends might be explained based on knowledge of mining conditions. A continuous personal dust monitor (CPDM) was also used during the collection of some samples to determine respirable dust concentrations, which were compared against estimated concentrations based on the particle-level analysis.

Jan 1, 2014

By Paul H. Johnson

Resource Engineering and Development, Inc. is designing and building a portable 150 to 225 TPD, flotation-cyanide leach plant with unitized, skid-mounted components. This plant design, with its portability, low capital investment, and high recovery of silver and gold from many partially oxidized ores, is well suited to treat many small, high-grade deposits, old waste dumps, and old mill tailing piles. A description is given of flotation and/or cyanide leach tests run on about 17 partially oxidized, newly mined ores; waste dump materials; placer slimes; and old mill tailings.

Jan 1, 1981