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By E. (Walt) van Walsum

The MPTM was first applied in the U.S.A. in 1950 as described by Lewis, W.E., 1951. The method was then abandoned in the USA and rediscovered some 20 years later in France where it was greatly improved and widened in its scope of application. It was subsequently successfully introduced to Italy and Spain. The technique, at its present stage of development, provides solutions to tunneling in soil and in the softer rock types, which often were troublesome geological environments for tunneling. When used in conjunction with drilling-and-blasting, over break, excessive vibration, noise and fissuring of the rock can all be avoided. When used as an alternative to the New Austrian Tunneling Method (NATM), the MPTM provides safe, full face tunneling in stead of multiple headings, excavated sequentially; in addition, surface settlement can be virtually eliminated. When used as an alternative to a TBM, the method's flexibility and low capital cost make it attractive. This attractiveness is enhanced when ground conditions are erratic or when the length of tunnel to be excavated is limited. The method holds promise for tunnels of large cross section, to be excavated in soft ground or rock with unconfined compressive strengths of less than 80 MPa (11 600 psi). While in itself not new, recognition and development of the method's potential are. Further development work, aimed at increasing the range over which the MPTM can be applied, is in progress.

Jan 1, 1993

By W. Burger

For the development of deep hard rock mines fast access to the orebody is critical. In some cases the mineralized area is more than 1500 m (5000 ft) below surface. Excavation of shafts or declines is typically on the critical path of the project schedule. Saving time on those activities can significantly increase the net present value of the mining project. Mechanical excavation methods are a step-change in excavation performance and labor safety compared to drill and blast operations. In hard rock conditions roadheaders can not be used effectively, so disc cutting is the first choice. For excavation of declines tunnel boring machines (TBM) can be used in many cases. These provide in certain rock conditions considerably higher production rates compared to drill and blast excavation.

Jan 1, 2010

By R. J. Barnes

Consider a typical blast at a surface gold mine in North America. For example, the low-grade area of Bench 4000 at AMAX Gold's Sleeper Mine (Winnemucca, Nevada). Bench 4000 is 20 feet high (=6m) , and blast holes are drilled and sampled on a 14 foot by 14 foot square grid (a4m x 4m). A representative blast includes between 50 and 150 holes, encompassing 15,000 to 45,000 tons of material (w14,000 to 41,000 metric tons).

Jan 1, 1989

By A. Spearing

According to a 2000 NIOSH report, about 100 million rock anchors are installed annually in coal mines in the USA. Most coal mines have conditions that are conducive to corrosion of the rock anchor and ancillaries (such as plates), yet the effect of this on the performance of the anchors has not been adequately researched and its effects are not understood or quantified in the USA. There is considerable research into corrosion in civil engineering applications on surface and underground but the corrosion of coal mine rock anchors is not necessarily the same because: ? In underground civil structures, water ingress is usually stopped as part of the construction process. ? Many rock bolts in mines are only partially resin grouted leaving part of the reinforcing member exposed to corrosive conditions. All cable bolts in coal mines are only partially resin grouted. ? Even when mine bolts are fully grouted, shrinkage cracks occur and the rock stresses can change due to adjacent mining that can cause the resin column around the bolt to fracture further under external shear or tensile stresses. Most coal mines therefore have ideal conditions for bolt corrosion.

Jan 1, 2010

By J. W. Hawkins

Understanding aquifer properties in surface mine backfill is essential for managing the groundwater flow system as well as controlling the formation and discharge of acid urine drainage. Slug tests (injection and withdrawal) performed on wells in mine spoil may yield two distinctly different response characteristics. One type of response is indicative of a porous media system. The second type of response indicates the presence of a pseudokarst system. The presence of voids or conduits in the backfill is indicated by an almost instantaneous partial recovery of the water level displacement. This rapid recovery is turbulent flow and cannot be analyzed by conventional (Darcian) methods. The turbulent flow may cause the calculated hydraulic conductivity to be less than the actual values. The slug dissipation surface area created by the voids contiguous to the test well add to the known dissipation surface area of the screened interval. This can cause the calculated hydraulic conductivity to be greater than the actual hydraulic conductivity or the aquifer to appear more permeable. Whenever analyzing data from aquifer tests in mine spoil, these potential problems must be kept in mind. In spite of the problems encountered during slug testing of spoil, the aquifer hydraulic parameters derived and the slug responses observed remain useful in the hydrologic characterization of a mine site.

Jan 1, 1994

By Barry Silverman

As a significant mineral supplier, consumer of primary fuels, and producer of wastes and emissions to air, water, and land, the domestic copper industry through its investment and operating decisions influences the nation's economy and the environment. In turn, the copper industries' decisions are influenced by various factors: government energy and environmental policies, economic conditions, and technological considerations. The authors have developed a framework for assessing in an integrated manner the impact of these factors on the future investment and operating decisions made by copper firms. Specifically, this model is designed to capture the technology forcing nature of regulatory constraints, the differential situation of individual copper deposits and plant locations, and the price of factor inputs and conditions in the nation's economy. The capability to do this has only become real because of the decision of the U.S. Bureau of Mines to create Mineral Availability system1 or MAS. This system contains detailed but confidential information about each mine and mill in each of 35 mineral industries." Without MAS or a similar information system, the utilization of the methodology we offer would be impractical, but with. MAS it offers a unique technique of dealing with environmental-resources policy questions.

Jan 1, 1979

By E. Topuz

This paper compares the production rates of the conventional shuttle car/ belt conveyor haulage with battery or diesel shuttle car haulage by using computer simulators developed at Virginia Polytechnic Institute and State University. The haulage parameters evaluated in the analyses include discharge rate and capacity of a feeder located at the section dump point, and the number and capacity of haulage units. The results allow many decision points to be identified including the optimum number of haulage units to maintain production above that obtainable from a shuttle car/conveyor system.

Jan 1, 1982

By J. A. Organiscak

The National Institute for Occupational Safety and Health (NIOSH) has investigated various factor effects on cab air filtration system performance. Factors experimentally investigated were intake filter efficiency, intake air leakage, intake filter loading (filter flow resistance), recirculation filter use, and wind penetration. Adding an intake pressurizer fan to the filtration system was also investigated. Results indicate that the intake filter efficiency and recirculation filter were the two most influential factors on cab protection performance. Use of a recirculation filter significantly reduced cab penetration over the intake air filter by itself due to the multiplicable filtration of the cab interior air. Cab penetration was also affected to a lesser extent by intake filter loading and air leakage. Adding an intake pressurizer fan notably increased intake airflow and cab pressure while providing only minor changes to cab penetration.

Jan 1, 2008

By G. A. Achilleos

The insufficiency of Boolean Logic and ?hard? decision making to represent and manage spatial data in set with their spatial errors comprises a remarkable difficulty for widely accepted estimation procedures, in realistic planning of space geometric problems and management through a GIS. Fuzzy logic as well as other theories such as the theory of Probabilities, Bayesian theory etc., contribute substantially towards this direction. Data are accompanied by their accuracy and are managed through the applications and modules of Spatial Analysis, aiming to access a decision with known accuracy and fuzziness. As it concerns the cases of waste sanitary landfill sites designing, which are based on the construction of a bank, the problem shown by this paper, seems to be quite serious. The determination of the theoretical waste disposals body in the landfill is based on an uncertain Digital Elevation Model (DEM). As this model is a result of a procedure enclosing errors and inaccuracies, it is for certain a non - error free model. Thus, the geometric computation of the excavation quantities and the waste disposals solid body volume, misquotes the expected standard theoretical computation and imports the need to decide and set a risk level for the project.

Jan 1, 2005

By A. Anani, K. Awuah-Offei

"Accounting for changing duty cycles in equipment matching maximizes equipment utilization and productivity. The objective of this study is to investigate if the optimal number of shuttle cars for a particular panel width is optimal in different segments of the panel. In this study, discrete event simulation (DES) is used to determine the optimal number of cars that maximizes productivity in each segment. Data from a real-life mine is used to validate the model. The study shows that the optimal number of cars for the entire panel may not be optimal for some of the defined segments. INTRODUCTION Fleet optimization is important for efficient mine management. Deploying the optimal fleet minimizes the capital and operating expenditure for particular operating conditions and production targets. In an operating mine, with an already existing fleet, deploying the optimal fleet maximizes productivity or minimizes production cost with the available resources. Hence, a lot of research has focused on how to determine the optimal fleet size for a mining operation, given particular operating conditions. Mine managers and engineers have successfully used discrete event simulation (DES) to determine the optimal fleet size in mines (Michalakopoulos, Roumpos, Galetakis, & Panagiotou, 2015; Awuah-Offei, Osei, & Askari-Nasab, 2011; Ben-Awuah, Kalantari, Pourrahimian, & Askari-Nasab, 2010; Govinda Raj, Vardhan, & Rao, 2009; Yuriy & Vayenas, 2008; Kwame Awuah-Offei, Temeng, & Al-Hassan, 2003). In most cases, the published work on this topic involves determining the number of hauling units to be matched to a loading unit. Many of these examples involve truck-shovel optimization. There are, however, some underground mining examples. For instance, we recently concluded work that involves fleet optimization in underground room and pillar (R&P) coal mining (Awuah-Offei & Anani, 2015). Generally, when DES is used in fleet optimization it involves three steps: (1) Build a valid model of the mining system capable of predicting the required outputs with varying fleet composition; (2) Design and conduct experiments that vary the fleet composition across all feasible options; and (3) Determine the optimal fleet based on the results of the simulation experiments. A major decision in the first step is which outputs should be modeled. Some examples in the literature include productivity, unit cost, loader utilization, queue length, and hauler waiting times (Awuah-Offei et al., 2011; Govinda Raj et al., 2009; Kwame Awuah-Offei et al., 2003). Often, more than one of these outputs are simulated and considered as the objective function of the optimization."

Jan 1, 2016

By S. K. Kawatra, V. Claremboux, S. Valluri

Carbon dioxide capture from coal-fired power plant flue gas and subsequent sequestration is expected to play a vital role in mitigating global climate change. To meet the growing need for CO2 capture Technology, Michigan Technological University is researching CO2 capture and Utilization. We have successfully converted CO2 into oxalic acid using an electrochemical approach. If oxalic acid can be produced in bulk from CO2, it can be used to leach rare earth minerals at low cost. Electrochemical reduction of CO2 to hydrocarbons and other chemicals is a complex multistep reaction with adsorbed intermediates. The exact reaction mechanisms leading to various products are not clear from the literature to date and will likely change over the range of conditions like pH, electrode potential, electrolyte medium, catalyst, etc. In this paper, we will present an idea of how the factors mentioned above will effect the electrochemical reduction of CO2 to Oxalic acid. INTRODUCTION. CO2 is thermodynamically quite stable, as shown by its highly negative heat of formation. Thus, it is expected that the formation of any useful chemical from CO2 will require the input of at least as much energy as geological sequestration. However, to be more effective the resulting economic value of the chemical need only pass the cost of the additional energy required beyond geological sequestration. This lends itself to two extremes: one where the quantity of energy required is low and one where the economic value of the additional energy is low. It is expected that CO2 can be reduced via electrolysis to several compounds. Of particular interest are formic acid, oxalic acid, methanol, ethanol, formaldehyde, and carbon monoxide (as a component to syn-gas). These chemicals have been reported as electrolytic products previously in literature and have considerable potential for application. EXPERIMENTAL Electrocatalytic Production of Oxalate from CO2 We are using membrane electrolysis cell to produce oxalate from CO2. A membrane electrolysis cell is a 2-chamber electrolysis cell where the chambers are separated by a selectively permeable membrane. To produce oxalate, a cation exchange membrane (which selectively exchanges cations) was used. Previous literature suggests that in the cathode chamber an organic electrolyte, such as tetraethylammonium perchlorate or tetraethylammonium bromide in dimethylformamide, are preferred3. In the anode chamber, a sodium hydroxide solution water is used. Carbon dioxide is then bubbled into the cathode chamber as a current is applied.

Jan 1, 2019

By Paul D. Tavares, John Forbes, Eric R. Drooff

As the existing major U.S. - Canada rail tunnel was too small to accommodate double-stack container cars, Canadian National Railways is constructing a new parallel tunnel with a 50% greater diameter. Starting in Sarnia, Ontario, the new shallow-cover bored tunnel runs under a large research building and several other structures in an oil refinery before travelling under the St. Clair River. Maximum predicted settlements to be caused by the 9.2 meter diameter earth pressure balance TBM in the soft St. Clair till were in excess of 100 millimeters. As such, these settlements had the potential to cause severe damage and disruption to the existing refinery. In order to reinforce the soft clays below the refinery research building and other structures, and to compensate for settlement caused by the tunnelling, the ground improvement method of Soil Fracture grouting was successfully applied for the first time in North America. This paper will describe the details of both the soil fracture grouting application and the elaborate electrolevel remote monitoring system used.

Jan 1, 1995

By A. F. Klebanov, K. N. Trubetskoy, M. Yu Khoudine, V. L. Postnikov

The information system of monitoring of mine receive layouts is being created In the "ROSUGOL" Company for the prompt analysis of the state-of-the-art of mining operations at under- ground and open cast mines of the Company, rapid and effective decision-making and elaboration of recommendations on the basic directions of enterprise development. The data bank storing the digital mapping and attributive information describing the actual background of mining operations at the enterprises of the Company is the core of the system. The Oracle database management system and the ARC1 INFO geographic information system have been chosen as basic software packages for the Project realisation. The updating of the information will be performed on a regular basis via the transmission of actual digital data on under- ground and open cast mine layouts In ARCIINFO conversion to the central office of the "ROSUGOL" in Moscow. Centralised storage of digital mapping and attributive data, database administration and navigation is effected with the Oracle software package. Access to the data in the operation mode with an interactive display map will be effected with the use of the local computer net of the "ROSUGOL."

Jan 1, 1996

By Thomas W. Healy, David V. Boger, Yee-Kwong Leong, Lee R. White, Peter J. Scales

The concentration of mineral slurries by conventional thickening devices is discussed. The role of additives on the compression of mineral slurries is also examined. Results for a range of flocculation conditions are presented. The compression of flocculated mineral slurries is found to be highly dependent on the fundamental particle-particle interaction forces and hence, the rheology of the particulate fluid. It is demonstrated that a detailed knowledge of the properties of both the mode of operation of the thickening device and of the solid/liquid interface is required for improvement in the rate and in particular, the extent of dewatering.

Jan 1, 1995

By Leonard Harris

The 1980s marked a boom in gold mining and exploration in the United States particularly in the state of Nevada which lifted this country to second place in the world, after South Africa, in gold production. With this boom came many positive aspects such as increased employment, increased investment, increased payment of federal and local taxes, higher purchases of goods and services and higher expenditures on social and economic uplift programs. With the arrival of Minera Yanacocha in Peru in 1992, the gold mining boom shifted to this country which has lifted Peru to first place in Latin America in 1996 and ninth place in the world in gold production. As in the case of the United States in the 1980s, similar positive impacts are being felt throughout Peru in the 1990s.

Jan 1, 1998

By J. Finch, W. Petruk, R. G. Pinard

An investigation was conducted to determine the minimum number of samples that must be studied by image analysis of polished sections to characterize a mill product and determine the apparent mineral liberation. It was found that a representative polished section cannot be prepared from an unscreened sample that has a wide size range of particles. Similarly, individual screened fractions are not representative of the sample because minerals are partitioned during screening, and the quantities of soft brittle minerals are increased in fine grained fractions, whereas the quantities of hard minerals are increased in coarse grained fractions. It is assumed that results obtained by combining data for a series of narrow size range screened fractions (one Tyler size range) are representative of the sample, and relatively accurate apparent mineral liberation data can be obtained for a mill product by analyzing each fraction and combining the data. Somewhat less accurate data would be obtained by analyzing a series of screened fractions that have a wider size range of particles (five Tyler size ranges).

Jan 1, 1987

By B. Waterman, R. Collins, V. R. K. Paruchuri, P. Gonzalez, H. Dijkman

"INTRODUCTION Mining and processing of sulfide ore bodies has the potential to solubilize sulfate. Gypsum in the host rock, as well as oxidation of sulfides during milling and processing can solubilize sulfate. Acid rock drainage (ARD) also has the potential to generate waters high in sulfate. Even after treatment of the ARD with lime, the treated water can have sulfate present in gypsum saturation levels. Most mine-sites reuse sulfate impacted water but as a mine nears closure, reuse options may be limited and water treatment becomes an option. Furthermore, sulfate discharge requirements, particularly for anti-degredation narrative standards, can be very strict. Freeport has investigated many new technologies to economically remove sulfate from these types of water. A Dutch company, Paques B.V. developed one of these technologies and it utilized biological reactors to convert sulfate into elemental sulfur in a 2-step process. In 1992 the first industrial reference of the SULFATEQTM technology was commissioned at the Nystar Budel zinc refinery in the Netherlands. PILOT PLANT TECHNOLOGY AND DESCRIPTION As shown in Figure 1, the plant contains several process steps, which can mainly be divided into the following sections: 1. Anaerobic biological system in which sulfate is reduced to hydrogen sulfide by sulfate reducing bacteria. 2. Aerobic biological system in which hydrogen sulfide is oxidized to elemental sulfur by sulfide oxidizing bacteria. 3. Solid/liquid separation in which sulfur, calcium carbonate and biomass solids are separated and dewatered. Sulfate impacted ground water is pumped to the feed water tank through a plate and frame heat exchanger to maintain the solution temperature around 95°F. A custom mix of micronutrients is dosed to the feed tank. This nutrient mixture provides essential elements for the growth of anaerobic and aerobic biomass. Urea is added to the feed tank and provides the required nitrogen source to the biomasses. The pretreated feed water is pumped into the anaerobic reactor. The reactor works on the gas lift principle. Sulfate reducing bacteria utilize hydrogen gas as electron donors and reduce sulfate to hydrogen sulfide. This reaction increases the alkalinity of the solution. Carbon dioxide gas is added in order to control the pH within working range of the reactor. Due to the low solubility of the hydrogen gas, the anaerobic gas mixture is recycled through the system. The gas mixture recycle also provides the gas lift for mixing within the anaerobic reactor."

Jan 1, 2016

By Birger Schmidt

INTRODUCTION Urban tunneling in soil poses a unique set of problems to planners, designers and contractors. One of the important concerns is the impact of tunneling on the environment: not only the effects of noise, vibrations, construction traffic and surface traffic diversions, but also the effects of ground movements and dewatering on existing structures and facilities. Underpinning or other protection of structures often consume more than 10% of the total construction cost of an urban rapid transit tunnel, and another unknown percentage is expended on construction procedures designed to minimize these environmental effects. Ideally, many basic planning and design decisions should be based on reliable predictions of ground movements due to tunneling. Some of these decisions are: the choice of tunnel alignment and depth to minimize risks and effects of ground movements; selection of schemes to protect existing structures through soil improvement or underpinning, or outright acquisition and possible' demolition; relocation of utilities; selection of procedures for construction monitoring and project control; and the choice of construction and lining methods. To make rational decisions of this nature, the owner and his designers must perform analyses that will balance risks and costs of a variety of alternatives; but to make meaningful risk analyses, they must employ rational methods of predicting ground movements and their effects and must know the reliability of these predictions. Of course, the risk analyses also must consider politics, public relations, insurance and liabilities.

Jan 1, 1974

By J. B. Rubinstein, V. J. Badenicov, S. T. Hall

A simulation technique of the flotation process and models for the solution of various problems are developed. A modular model of column flotation is constructed taking into account the kinetic relationship of the process and the hydrodynamic regime in the cell. Based on this, a technique of calculating the column parameters based on laboratory tests is developed (scaling-up), and applied for calcetest results is developed (scaling-up), and applied for calculating the design of commercial-scale columns.

Jan 1, 1996

By Stanislaw Nawrat, Waclaw Dziurzynski

An increasing concentration of coal production, especially in the circumstances of intensive methane inflow makes the coal mine managing staff apply new techniques of safe mining. It paves also the way for scientists to develop new directions of investigations and implementation of state-of -the- art technical solutions. Simultaneously, it could be noticed that the funds assigned for expansive 'En situ ' investigation are continuously decreasing. Better and better results are reached when applying computer technique in calculations of the parameters of ventilation process. Recent theoretical and experimental investigations of air and gas (methane) flow in longwall areas with caving, combined with the implementation of methane drainage system allowed to create, a mathematical model and consequently to elaborate a computer supported numerical simulation of discussed phenomena. The mathematical model has been modified and the simulation program was prepared in such a way that the software is convenient for a user looking for an optimal solution. The paper presented the methodology of optimal choice of following parameters: - ventilation system - rate of flow through the wall. The procedure takes into consideration keeping a safe level of concentration methane in air flowing through the longwall as well as the criterion of maximum methane concentration within the methane drainage pipe line. Results of variant computer simulation regarding the longwall with caving are shown in graphs and tables.

Jan 1, 1995