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By Michael Francis, Chris Darton

More than 55 km of tunnels have been constructed by TBM in the last 12 years to refurbish and upgrade the high voltage cable network in London. These include a tunnel of 20km length using EPBM machines in both clay and granular soils. Route selection was made with reference to subsurface structures, existing ground conditions, using suitable shaft locations addressing environmental concerns. The complex interfaces to manage included obtaining of consents to the coordination of multiple suppliers. The paper describes how all these challenges have been met successfully and how technology has been employed to provide for safe construction and operation in the congested urban environment.

Jan 1, 2003

By M. Robb, S. J. Bate, M. Boisvert

The never-ending quest for gold-bearing ore deposits is a primary industry in Canada, employing people of widely differing expertise. The exploration models for gold deposits are generally geologically complex and the targets have relatively small cross-sectional areas. These problems are compounded in Canada by the minimal outcrop exposure in most mineral provinces and the high percentage of water-covered areas. Naturally the chances of successfully delineating an economic gold deposit are very much greater if all parties involved can act as a team of explorationists constantly confemng amongst themselves particularly as the applicable disciplines generally overlap and complement each other. Three case histories (see Figure 1) are presented to illustrate this philosophy with emphasis placed on the role of the geophysicist in translating the exploration model as defined by the geologist into physically measurable parameters and identifying target areas with similar characteristics. The Conwest-Miminiska property in Ontario is a grassroots exploration play. Additional ore reserves needed to be delineated on the Salmita property in the Northwest Territories. At Laura Lake, near Chapais, Quebec geophysical methods were employed to trace thin high-grade mineral intersections under deep overburden and severe cultural interference.

Jan 1, 1989

By R. A. * Russell, J. R. * Brooks, E. J. Griffith

In 1967, a major impoundment to contain phosphate tailings was built near Columbia, TN. Precise records were maintained on the behavior of the impoundment throughout its 20-year active life. The volume of the impoundment was determined. The DNT (dry net tons) of solids added to the impoundment were continuously measured. The rise of the mud line in the impoundment was measured monthly. The density of the settled strata was determined, as required to understand the behavior of the settled tailings. And experiments were per formed to increase the settled density of the clays. The impoundment is currently being retired and stabilized. It covers more than 400 acres and the settled muds are almost 200 ft thick. The clays have been sufficiently solidified with electroendosmosis to support the growth of cypress trees. More than three milllion trees are being planted.

Jan 1, 1992

By Randal J. Barnes

There are many methods available for the estimation of geologic parameters (Popoff, 1966; Barnes, 1980). In the last decade a new and relatively sophisticated technique using statistical theory has emerged: geostatistical kriging (David, 1977; Journal and Huijbregts, 1978; Rendu, 1978). An interesting property of geostatistical estimation is that when a geologic parameter is estimated for a given volume, not only is the estimate generated but an associated measure of certainty is produced as well. This statistical measure of estimation confidence is called the estimation variance. While the concept of an estimation variance is universally considered to be a good idea, mining engineers and geologists do not currently have the tools to incorporate it into their planning and quantitative analysis. This paper attempts to develop and present some of the necessary tools required to incorporate estimation uncertainty into mine planning. Geologic uncertainty is portrayed as an economic business risk. This risk is objectively characterized, and-the associated cost is quantified. Geologic delineation sampling is viewed in this light as an economic commodity with an associated cost and value. A coal mine planning example is used as a focus in this presentation. The data used is real, though it has been modified to maintain data security and project anonymity.

Jan 1, 1986

By D. Robert Weir

The pioneers in pressure hydrometallurgy have provided a solid foundation during the past four decades. The pressure techniques are now capable of being used to push back the frontiers in the winning of metals. Pressure hydrometallurgy has been used to meet the objectives of extracting metals; purifying metal solutions, recovering metals; and rendering waste streams acceptable for disposal to waste repositories and the environment. Some examples of each of these functions are briefly reviewed. The applicability of pressure techniques to the recovery of precious metals is discussed.

Jan 1, 1985

By E. W. Hawk

he power generation industry may be required to reduce carbon dioxide (C02) emissions if regulations related to global climate change are enacted. Coal-fired generation emits more than 80% of the power sector CO2 and would be a likely target for CO2 reductions. Compliance with the Kyoto Protocol will require a 33% reduction from the projected year 2012 emission level, even with moderate load growth. This article describes an analysis of power industry CO2 reduction options and their costs. It assesses how a generator would make compliance decisions under a mandatory CO2 emissions reduction program. Carbon sequestration, fuel switching and new plant construction are considered. The Global Climate Change Treaty signed at the Rio de Janiero Earth Summit in June 1992 set the long-term goal of stabilizing CO2 concentration in the atmosphere. The December 1997 Kyoto Protocol established short-term mandatory targets for the United States and 37 other developed countries. The United States' target is a 7% decrease by 2012 from the 1990 "greenhouse gas" level. Developing countries are exempted from reductions, according to the Kyoto Protocol, despite projections that indicate a significant increase in their emission levels. The Kyoto Protocol must be ratified by the US Senate. US power industry carbon emissions were 490 Mt (540 million st) in 1990 and are projected to be 680 Mt (749 million st) in 2012, according to the US Energy Information Administration. Coal-fired generation emits more than 80% of the power sector CO2. Assuming that the power industry is only required to reduce emissions by a proportional share, a 33% emission reduction, or 225 Mt (248 million st) of carbon, would be required to comply with

Jan 1, 1999

The selected list of sources of information on geology and mining in this section is provided to facilitate locating the major governmental and private entities in position to furnish such information, including societies and institutes; colleges, universities and technical schools; and magazines, yearbooks and mine directories, plus a number of general texts. In the case of publications, it should be noted that, in addition to those listed, most of the governmental and private organizations publish a wide variety of reports, bulletins, monographs, surveys and the like, including, in the case of governmental agencies, production statistics. The names of the mining schools and colleges in the following, with some exceptions, were taken from the International Handbook of Universities and & her Institutions of Higher Learning, and the Commonwealth Universities Yearbook, with the kind permission of the International Association of Universities, Paris, and the Association of Commonwealth Universities, London, owners of the copyrights. Abbreviations in the listings include the following: A. P., B. P, and C. P., Apartado Postal, Boite Postal and Caixa Postal (post office boxes); Br., Branch; and F., Faculty.

Jan 1, 1973

By Larry J. Hughes

Ground-based electrical geophysical techniques have be valuable for three indirect exploration strategies: "tracer" sulfide mineralization, 2) mapping structure with or controlling mineralization, and 3) mapping proven to 1) mapping? associated alteration zones. When sulfide mineralization is associated with gold, it often can be mapped using induced polarization (IP). This technique can detect pyrite in amounts as small as 0.2% by volume, and in some cases can distinguish pyrite from anomalies due to graphite and clays. A case history illustrates mapping sulfides in a shear zone. Structure and alteration mapping are often the domain of controlled source audio-frequency magnetotellurics (CSAMT) due to the superior lateral resolution and depth penetration of this technique. Typical CSAMT targets include silicified sediments and volcanics, faults, brecciated zones, argillic alteration, clay and graphite horizons, and certain lithologies. Examples of mapping silicification and mapping epithermal alteration are presented in CSAMT case histories over Cannon mine in Washington and Hishikari mine in southern Japan. In our experience, four things are needed to use geophysics effectively in precious metals exploration. First, the explorationist must correctly identify the exploration stage at which the geophysics is most useful. Second, the explorationist must clearly define the types of "tracer" mineralization, host geology, or alteration which need to be defined by the geophysics. Third, the right electrical technique needs to be applied to the problem to provide the best chance of success. Fourth, the explorationist must be willing to commit adequate finances to do the geophysics properly. With careful adherence to these principles, geophysics can greatly enhance exploration success while reducing the total cost of exploration.

Jan 1, 1989

By S. K. Kawatra, K. A. O, DeLa&apos

On-line sensors and process controls are important for efficient operation of coal preparation plants. The objective of this paper is to describe the current practice in on-line measurement of composition, density, moisture, level, flow and weight. This paper also discusses how on-line sensors can be implemented in process control, and how sensors which are currently being developed can be utilized.

Jan 1, 1988

By Jamal Rostami, Jürgen Schmitt, Rohola Hasanpour

"Double Shield TBMs can be used in fast track projects for accelerated completion where there is limited information available on ground conditions and there are possibilities of encountering weak ground and shear zones. As such, the shielded TBMs are the primary choice of the machines in long tunnels, but face the possibility of entrapment in squeezing ground, which entails long delays and major risks. This paper examines the possibility of using ground improvement methods to increase ground strength, and thus, increase the capability of the machines to cope with squeezing ground conditions. In this study, 3D finite difference simulation of a shielded TBM in squeezing ground was performed to estimate the operational parameters including required thrust to get a machine out of an entrapment. This analysis was also used to evaluate the possibility of preventing machine jamming by the implementation of pre-excavation ground improvement to increase the strength of the ground. INTRODUCTION In order to face adverse tunneling conditions especially using a shielded TBM in squeezing ground, new shield designs, with extra thrust and torque, step shield geometry with reduced shield diameter from front to the back, and conical shape shields have been used. In addition, many of the new machines have the capability to implement ground improvement at distances up to 50 m ahead of the face in order to reinforce the ground and further increase in their chances to cope with squeezing ground conditions. While these features have been added to the machine, there has not been a thorough evaluation of their impact on improving the chances to avoid machine jamming in weak rocks at high depth, which is conducive to rapid convergence of the ground."

Jan 1, 2016

By K. S. E. Forssberg, K. Hanumantha Roa

Batch flotation tests are carried out with phosphatic material from LKAB, Sweden containing carbonatic and siliceous gangue while using sodium oleate as collector and sodium silicate as modifier. The pulp liquid is analysed for oleate, silicate, carbon dioxide, calcium, magnesium and phosphorous after each flotation test under different reagent conditions and flotation pH. Theoretical calculations of thermodynamic chemical equilibria in apatite-calcite-sodium oleate-sodium silicate system have been carried out with the help of SOLGASWATER computer program. During the calculations, the chemical variables are maintained similar to the operating chemical variables in flotation. A comparision between the experimental and theoretical chemical equilibria has been made and the flotation behaviour of apatite is discussed with reference to the theoretically calculated pulp model.

Jan 1, 1993

By Christopher Haycocks

Self-supporting, open stoping underground mining methods are some of the earliest, starting with the prehistoric flint mines of Europe and the Egyptian gold mines of Nubia in the time of the pharaohs. When the early miner created an opening, it had to be inherently stable and self-supporting to enable him to continue. Therefore, as mining progressed beyond simple gophering, self-supported open stoping methods were devised to meet the needs of individual ore bodies. Timber for support appears in mines as early as 1000 BC, but this was for no more than local ground control. The ingenuity of mining engineers through history has so refined open stoping methods that today they produce more tonnage than any other mining system. Self-supported open stoping finds its application in moderate to strong rocks that exhibit little jointing or fiagmentation. Good back, hanging wall, and footwall conditions that require no more than incidental support are an essential part of these mining methods. Open stoping methods find applications in all inclinations of ore body from flat to vertical, and where ore movement may be either mechanical or under the influence of gravity. Table 18.0.1 demonstrates the range of ore bodies suitable for open stoping, with particular reference to their dip and the deposit thickness. Most of the flat-dipping applications use ore pillars for overall support and ground control that may be recovered under some conditions after completion of normal stoping practices. In steeper ore bodies, rib, crown, and sill pillars used to block out the ore may be recovered subsequent to the completion of stoping. Open stopes are frequently filled to facilitate pillar recovery. Two of the methods, vertical crater retreat (VCR) and shrinkage stoping, utilize fragmented ore for temporary support in the stopes. In these two cases, the stope is not strictly open until after drawdown.

Jan 1, 2008

By T. Hall, R. Ferris

Waterjets and diamond wire saws have raised the productivity and lowered the cost in dimensional granite quarries. While the cost of diamond wire sawing is substantially lower than waterjet, the judicial use of the waterjet can simplify and improve the overall operating efficiency and predictability. Granite is the hardest commercial stone and only the gem-stones garnet and diamonds are harder. The introduction of industrial diamonds has made it possible to quarry and process granite at costs equal to or less than other natural stones – making granite, with its superior properties, the best value available.

Jan 1, 2004

By Murray Malott

The Sheppard Subway extension is currently being constructed in Toronto, Canada for the Toronto Transit Commission (TTC). McNally International Inc., in a joint venture with PCL and the Foundation Company of Canada were awarded the Twin Tunnels contract of the Sheppard extension. The Twin Tunnels project is approximately 4.4 km in length and consists of two separate twin bore drives each 3.3 km and 650 m in length and approximately 400 m of cut and cover construction. This paper presents a case history of the construction of the soft ground tunnels through the complex Toronto glacial deposits using two 5.9 m outside diameter Lovat earth pressure balance (EPB) tunnel boring machines.

Jan 1, 1999

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"Iron ore in Minnesota probably carries a heavier tax burden than any mineral in any other place in the world. The State Tax Commission, created in 1907, originated the system, and with the assistance of the School of Mines is constantly making such adjustments, changes and increases as appear necessary, in order to place mineral reserves on the assessment rolls at their true and full present taxable value. The ore bodies on the Mesabi are so well defined by drilling and underground devel¬opment that it is possible to estimate very exactly the volume on every forty acres of land taken as a unit. This is done by the operating or holding company and reported annually to the Tax Commission, Who check the estimates, having all data, and- proceed to fix the valuation for taxation purposes.The first step is to ascertain a general average selling price in open market, over a period of years ; then the total cost per ton (exclusive of royalty) to produce and market the ore. The difference between the average selling price and producing cost per ton is taken as the future full value per ton. This is then discounted at a rate of interest that represents the present and possible future worth of money, over a period of years that will be required to exhaust the ore body, giving the present full value per ton., Iron ore is taxed at 50 per cent of its full value, while other property is taxed at 33 1/3 per cent and 25 per cent."

Jan 1, 1920

By K. R. Weller, U. J. Sterns, P. S. B. Stewart

Complex sulphide ores usually require very fine grinding of the whole ore stream to achieve adequate liberation. Recent improvements to DSM screens have made this device appear competitive with cyclones in circuits treating these ores. A DSM screen and cyclones were tested in pilot-scale grinding of a copper, lead, zinc ore and the resultant data were used to establish a multi-component simulation model. The model was used to assess the influences of mill environment, circuit flows and pulp densities, final product properties (size, relative size and SG of the values, and liberation characteristics) and a second grinding circuit on capacity and product size distributions, and hence define conditions for which one device is better than the other.

Jan 1, 1992

By Zhongxue Li, Baolu Zhou, Yiqing Zhao

"Rare earth elements (REEs) are a kind of new materials which have excellent optical, electrical and magnetic properties, and they play an important role in the development of high technology and green energy industries. With abundant reserves and a wide range of REE type, rare earth industry has a rapid development in China in recent years. However, environmental issues associated with REE exploitation have severely restricted the sustainable development of rare earth industry in China. At present, literatures on the externalities of REE exploitation are very limited, especially in China. This paper builds an evaluation model based on life cycle evaluation to estimate the external costs of REE exploitation at Bayan Obo. The results show that the external costs for producing one metric tonne of rare earth oxides (REO) in Bayan Obo was CNY 34739 in 2013, the external costs of waste gas, waste water, radioactive substance, REE resource depletion, and land occupation are CNY 14945, 12515, 1400, 3199, and 2680, respectively. Waste gas and water constitute about 79% of the total external costs. The internalization of the external costs would reduce the financial profit of Northern Rare Earth (Group) by 18%. This study has taken into account only those externalities whose market values can be estimated, and therefore the external costs of REE exploitation in Bayan Obo is likely to be underestimated. The results fill the gap in literature and provide further understanding on the external cost of REE exploitation.Introduction / Background Along with increasing concern about environmental pollution problems caused by the usage of fossil fuel and the shortage of fossil energy, a transition has occurred where development has moved toward green and renewable energy sources with less pollutant emissions (Stegen 2015). Rare earth elements (REE) are a group of important raw materials for these trends since they have unique magnetic, electronic and optical properties, and thus make them widely used in making high-performance magnets and energy saving lamps (U.S. DOE 2010). In addition, REE are crucial for manufacturing of widespread high-tech applications in medical, defense and electronic industries. Many countries have made medium-term and long-term plans for the development of their REE industries, and the annual growth rate of global REE demand is expected to increase by 6% by 2020, and reach about 170,000 metric tons of rare earth oxides (REO) by 2020 (Rollat et al 2016)."

Jan 1, 2017

By Floyd C. Bossard

A method of hand-calculating the air-cooling requirements of a conceptualized underground mining operation is presented for the reader's orientation. Separate air heat load calculations were conducted for adiabatic compression, electromechanical equipment, wallrock, broken rock, groundwater, and blasting operations. The air heat sources were calculated for four mining levels under conditions representative of a typical planned mining operation at depth. The total heat gain on each level will approximate the level air-cooling requirements. The results of these hand calculations can be further modified by the use of mine ventilation computer software that refine the heat-source calculations, predict underground ambient air temperatures, and establish the air-cooling requirements of a mine. INTRODUCTION The principal mining method employed is a modified vertical crater retreat (VCR) blasthole operation. Typical scopes range from 20 to 40 feet wide, 75 to 100 feet long, and 100 feet in height. Six and one-half inch blastholes are drilled with an "in the hole" hammer drill. Eight-foot high horizontal rounds are blasted down. Mucking of ore from the undercut to orepass is done with LHD equipment operated from a remote control station. Backfill includes hydraulically placed tailings with cement, and waste rock when available. Stope access is from ramp sub-levels on 50-foot vertical intervals. Crosscuts are ramped down to the first stope cut 25 feet below the sub-level elevation. Then the crosscuts are raised by taking down the back when each stope cut is completed, until an elevation 25 feet above the sub-level is reached. The crosscuts are filled with tailings, and/or waste rock. See Figure 1. Typically, a two-pronged approach to defining the air-cooling requirements is conducted. First, the principal sources that make up the air heat load are individually hand-calculated. Second, projections of mine heat load are calculated by utilizing computer modeling techniques. This paper discusses the first method (hand calculations) of determining the individual components of heat flow into the mine. CALCULATED AIR HEAT LOADS Adiabatic Compression The plans for the mine include delivery of 300,000 cfm of air to ventilate the lower level operation. This is equivalent to approximately 200 cfm/ton of rock produced (300,000 cfm/1500 tpd of ore and waste). As air flows down a shaft, with no heat interchange between the shaft and air and no evaporation of moisture taking place, the air is heated in the same way as if it were compressed in a compressor. Dry air increases in temperature about 5.4°F per 1000 feet. One BTU is added to each pound of air for every 778 feet of decrease in elevation, or is subtracted for the same elevation increase. For dry air, the dry-bulb temperature change is 1/(0.24 x 778) = 0.00535°F/ft., or 1°F/187 ft. elevation. Auto-compression may be masked by the presence of other heating or cooling sources, such as shaft wallrock, groundwater, air and water lines, electrical facilities, etc. The major factors influencing the temperature of the air delivered underground by a shaft are (1) the night time cool air temperature's effect on the rock or lining of the shaft, (2) temperature gradient of ground rock related to depth, and (3) evaporation of moisture within the shaft which increases the latent temperature and decreases the sensible temperature. [Calculation For Adiabatic Heat of Compression] a. Assumptions: 1. Three hundred thousand cfm of fresh air at 3000 level has increased in temperature during the summertime to the point where it has little available cooling power. Air-cooling will be required on 3000 Level and below. 2. Elevation of 3000 Level is approximately +1000 ft. above sea level.

Jan 1, 1993

By Larry DeGraff

With the increase of new mine development in the past several years, many coal mines have decided to self- perform the design and construction for their slope development projects. The development process of determining the proper configuration is challenging, and a major economical consideration. Greenbrier Smokeless Minerals engineering staff and consultants, along with DSI/American Commercial, developed a support configuration that was best suited for their slope. The developmental process took into consideration the length of slope, depth of slope at the high-wall transition, economics of a single or multiple entries, waterproofing, stresses on the steel supports and lagging during the backfilling operation. This paper describes the developmental concept of using a single entry, side by side configuration, using steel ?Banjo String? supports with steel plank lagging, to develop a long term permanent installation in a cut and cover application.

Jan 1, 2009

By Bing Wang, Jingli Fan, Qinying Song, Fengyu Li, Xian Zhang

"With the background of water shortages and serious water pollution, issues of water involved in energy exploration and utilization have become critical problems affecting urban water usage. In order to identify the relationships of the energy-water nexus, this paper characterizes the energy-water nexus literature using a bibliometric method and based on the Chinese National Knowledge Infrastructure database platform. The results reveal that 1) Scientific outcomes in this field have increased sharply since 2003, with a slightly higher growth rate than that of general disciplines. 2) China Water Resources, Yangtze River and Express Water Resources & Hydropower Information are the dominant journals, and the main research fields include industrial economics, environmental science, and management, among other disciplines. 3) Hohai University, the Chinese Hydraulic Engineering Society, the Institute of Geographic Sciences and Natural Resources Research, and the Changjiang Water Resources Commission are the main research institutions in this field. However, the proportion of publications of these institutions is not high, which suggests that there is no institution dominating this field. 4) According to the keyword analysis, the hot spots in this field include ecological environment, sustainable development, environmental protection, climate change, etc. Energy-mining related keywords have increased over time, implying that the energy-water nexus from the perspective of the energy exploitation industry can become a key issue. At the same time, the frequency of keywords related to sustainable development has been maintained at a high level, and the studies concerned with the impacts of climate change were introduced into this field relatively late. The conclusion of this study provides a foundation for a comprehensive understanding of the current situation as well as for further research in the energy-water nexus field.Introduction As an important strategic resource for national economic and social sustainable development, water has been increasingly focused on by the Chinese Government. Over the next decade, the total water demand of China will continue to grow steadily, which lead to a significant trend of increasing water consumption in the future (Zhang 2013). To reasonably exploit, utilize, conserve and protect water resources, the Water Law of the People's Republic of China was enacted by the members of the 9th National People's Congress Standing Committee in 1988 and after multiple revisions, the latest of which, in September 1, 2016, has involved water infrastructures in the national economic and social development plans of the government at all levels and regulated the rationale for water engineering construction. Thus, in the context of serious water shortages and water pollution, China’s government has taken several measures to make rational use of water resources."

Jan 1, 2017