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By H. J. H. Pieterse

This paper highlights the mineralogy of the Barrick Goldstrike Mines Inc. area. The mine is located at the north end of the Tuscarora Spur and is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend. The Betze, Post, and Meikle Mine are major deposits located in the area. The deportment of gold, its leachability, and various process options are also evaluated. Particular emphasis is given to the practical and economic considerations of ore control, and routing of ore to a process option.

Jan 1, 1993

By J. Abbott

This paper gives a brief description of the Compania Ninera del Pacifico (CNP) a subsidiary of the Campania Acero del Pacifico (CAP), its participation in the Chilean Iron Ore mining and the gradual development of its activities. mainly in this paper, it is explained the CNP experience in the production of 34 million tons of self-fluxing pellets for Blast Furnace in a period of ten years in its Huasco Pellets Plant.

Jan 1, 1989

By A. G. Mayton

Bureau of Mines research has addressed improved operator protection for thin-seam shuttle cars. Because of working height restrictions in thin-seam mines (1.22 m or 48 in), MSHA regulations require that-canopy protection on shuttle cars be provided only in mines 1.07 m (42 in) and greater; however, variances are given to mines 1.22 m (48 in) and below. This paper reviews past Bureau efforts to develop protective structures for thin-seam shuttle car operators. The paper also discusses recent research leading to a novel method of protecting shuttle car operators, in mines as low as 1.02 m (40 in), through the use of a cross-car, end-mounted operator compartment.

Jan 1, 1989

By Christopher M. St. John, Michael P. Hardy

INTRODUCTION Geotechnical models, particularly those based on the finite element method, have been available to aid in en¬gineering design of underground mining excavations for over ten years. Despite this fact there are remarkably few cases of their use in mine design documented in the literature. It is therefore to be anticipated that many potential users of these models are relatively unaware of their capabilities and limitations and also of the form and detail of geotechnical data needed for their success¬ful application. This subsection attempts to address this problem by discussing the different types of numerical models now available and by noting how some of them have been used to study a variety of problems associated with underground mining. The subsection concludes by discussing the applica¬tion of the displacement discontinuity method to the de¬sign of possible mining systems for the copper-nickel deposits of northeastern Minnesota. The object of the analyses, which were nonsite specific, was to determine the significance of geotechnical parameters, such as ini¬tial stress and rock structure, on the stability of under¬ground excavations and hence to provide guidance for future geotechnical investigation. NUMERICAL MODELS In the geomechanical design of underground mining openings, use is made of numerical models that repre¬sent or simulate the large-scale mechanical behavior of rock. There has been less interest in analysis involving fluid flow and heat transfer, but with increasing interest in such areas as in-situ retorting and solution mining it is likely that there will be a growing need for numerical models embracing and coupling all three physical proc¬esses. However, the emphasis in this subsection will be on mechanical behavior. Models which simulate such behavior will be divided into two groups: continuum models and discontinuum models. These will be dis¬cussed in turn in order that some insight into alternative solution strategies and their merits may be gained. Continuum Models Almost all geomechanical numerical models must be classed as continuum models even though particular computer codes incorporate special provisions for rep¬resenting discontinuities such as faults, bedding planes, or joints. They are continuum models because they pro¬vide solutions for cases where material behavior is governed by the differential equations of continuum mechanics. Two basic solution strategies for such equa¬tions may be identified immediately: the differential ap¬proach and the integral approach. In the differential approach a means of approximating the differential equations over the entire region of interest is sought. In the integral approach use is made of fundamental solutions from continuum mechanics, and these are used to construct a solution to the whole problem, making approximations only on the boundaries of the region of interest. The several differential and integral methods are identified in Table 1. Differential Methods: Problems in continuum me¬chanics involve the solution of three types of partial differential equations. Two of these govern the behavior in so-called initial value problems, in which variables change both in time and in space. Examples of such problems include nonsteady heat transfer and fluid flow, and stress wave propagation. The last type of partial differential equation governs the behavior in boundary value problems. In these, variation is in space but not in time. Solution of initial value problems may be achieved in two significantly different methods: implicit and ex¬plicit. The differences between these two methods will be illustrated by considering a very simple initial value problem, that of one-dimensional heat diffusion. The equation governing this process may be written as: [ ] where T is temperature, K is thermal conductivity, p is density, c is specific heat, t is time, and x is the spacial coordinate. In finite difference form this equation might be written as: [ ] where the superscripts refer to the time and the sub¬scripts to the spacial location. Several solution strategies for this equation have been used. Two important ones may be illustrated very simply by discussing the signifi¬cance of the superscript * on the right-hand side of the equation. If i + 1 is substituted for * then the second derivative of the temperature with respect to distance is evaluated at the end of the next time step (using tem¬peratures not already known). Such an approach leads to a set of equations involving unknown temperatures and a solution procedure which is referred to as being implicit. The important characteristic of the implicit procedure is that it leads to a set of equations that must be solved for each time at which the temperature dis¬tribution is required. If instead of substituting (i + 1) for the superscript *, i is substituted, the following equation is obtained: [ ] {In this case the new temperature is defined in terms of an already known temperature distribution. The solution procedure is now known as explicit and has the impor¬tant characteristic that there are no equations that have to be stored or solved. A practical advantage of this

Jan 1, 1982

By J. F. Strunk Jr., K. M. Maestas, Y. Chai, R. Legrand, R. L. Henry

"Groundwater with elevated sulfate and metals was treated using a sulfate-reducing pilot PRB consisting of a series of six 55-gallon drums filled with ZVI (Fe0), wood chips, brewer’s grain, limestone, and emulsified vegetable oil (EVO). Sulfate was reduced from >3000 to <250 mg/L and Cd, Cu, Mn, Ni, and Zn concentrations declined up to 3 orders of magnitude in 2 months. After 6 months of operation at a 7.5-day retention time, sulfate broke through. The system was then rejuvenated by injecting EVO in each drum and operated for 5 more months at a 9-day retention time. Sulfate-reducing bacteria in the pilot system grew by 3 to 4 orders of magnitude in 2 months. Some cementation of the PRB media was observed in the first 2 drums after processing 25 pore volumes of water, due to preferential upstream precipitation of sulfides; this can be avoided through operational modifications. Resulting permeability losses were estimated at 0.1% to 1% per year. Absorption/desorption was tested at bench scale to evaluate the use of various oil-soaked sorbents as a slow-release source of dissolved carbon. The tests show that oil sorbents can increase the useful life of a PRB between oil refills to over 100 pore volumes. INTRODUCTION High sulfate concentrations, low pH, and dissolved metal exceedances are common characteristics of mining-influenced water (MIW). Above-ground such MIW is commonly treated using biochemical reactors (BCR). In a BCR, water generally flows vertically downward through a layer of biomass, such as wood chips, manure, etc. The dissolved organics resulting from the decay of this material are oxidized first by microbes using oxygen; when oxygen is exhausted, other bacteria can use nitrate, and then sulfate to oxidize organics. Sulfate-reducing bacteria (SRB) reduce sulfate to sulfide, which quickly reacts with metals to form largely insoluble and stable metal sulfides. These reactions can be summarized as follows:"

Jan 1, 2016

By Hongjie Yu, Mike Mooney

Transitions between geological/geotechnical soil units have a critical impact on the operation and performance of a tunnel boring machine (TBM). Geostatistics-based probabilistic modeling is used to quantify the uncertainty in soil transition locations. This paper presents two unique soft-ground tunneling case studies where the results from the geostatistics-based probabilistic modeling are compared to the TBM data and as-encountered ground conditions derived from the actual TBM data. The assessment enhances the confidence in using geostatistics to improve ground awareness for efficient tunnel construction, minimizing different site condition (DSC) claims, and improving decision-making on tunnel projects.

Dec 1, 2022

By Robert C. Salak

The era of low-seam mining with continuous haulage has been here for quite some time. Typical tonnages in companies such as Terry Glenn Coal are currently averaging 405 tonnes per shift in .8m coal. JoAnn Coal has averaged 453.6 tonnes per shift in .775m to .825m coal for the past four years. John Chaney of Chaney Coal has averaged 297 tonnes per shift in .6m to .65m coal. There are many other mines that are experiencing similar success and with maintenance costs that are averaging $.10 to $.40 per tonne. These figures have been documented and can be verified by the operators.

Jan 1, 1981

By Hu Wenjun, Li Maonan

Mine ventilation systems mostly are ventilation networks with fixed-quantity branches. The solution to the problem of ventilation networks with fixed-quantity branches is obtained by choosing the fixed quantity branches as chords and using Hardy Cross iteration method. The solution usually is feasible but may be not economical. This paper takes minimal annual ventilation electricity cost as an object, considering the power of main fans and boosters, natural ventilation pressures and resistances of regulators, and builds up a nonlinear programming model. A set of initial values of the nonlinear programming can be obtained by using Hardy Cross method, The MAP technique then used to find a set of local optimal solution The running procedure with a simple example is dicussed. Mine ventilation systems mostly are ventilation networks with fixed quantity branches. In the networks, air quantity of branches are generaly regulated by increasing branch resistance or air pressure. A comon approch to the of the networks with fixed quantity branches is to formulate it based on Kirchhoff&apos;s current and voltage laws and the solution is obtained by Hardy Cross iterative technique. The solution usualy is feasible but may be not economical. The optimal plan of air quntities regulation of mine ventilation network should be to make the solution satisfy both required quantity of work places and minimal ventilation operating cost. It is the purpose of this paper to introduce a new approch and computational experience of nonlinear programming of the optimal problem.

Jan 1, 1991

By C. E. Jordan

Under its program of advancing minerals technology, the Federal Bureau of Mines has developed a laboratory apparatus for continuous separation of minerals according to their dielectric properties. The unit consists of a rotating wire grid drum electrode and a fixed curved wire screen electrode positioned 3 mm apart. By applying high voltage across the electrodes, which are immersed in a dielectric fluid medium, a high-gradient electric field is produced. The high-dielectric-constant minerals are attracted and conveyed through the separator by the rotating drum electrode, whereas the low-dielectric-constant minerals settle through the fixed electrode. In typical tests, a sample of Montana chromite ore containing 43 percent chromite was concentrated to 72 percent chromite with 90 percent recovery.

Jan 1, 1977

By Phillip J. Maddex

Transportation is a major part of yours in the industrial minerals industry. Whereas federal income taxes merely take 50 per cent of your firms profits, transportation cost may take 50 per cent of the gross realization - selling price plus transportation - on your product, f. o. b. customers plant.

Jan 1, 1969

By Dal Negro Enrico, Andrea Picchio, Boscaro Alessandro

"The Doha Metro Project is one of the most relevant ongoing tunneling projects. The whole project consists of about 100 km of tunnels with 21 EPB TBMs working in the same period. Due to the variability of the geological formations, the soil conditioning is a relevant aspect of this project because the parameters should be frequently adjusted to achieve the best performances of the TBMs. The study of the soil conditioning has been carried out accurately to obtain the best results on site. The study of the geotechnical data, the choice of the most suitable foaming agents and polymers and the laboratory study of the soil conditioning has been a fundamental part of the job. The application of the soil conditioning products on site with the analysis of the TBM data have confirmed the preliminary study results with some correlation between the features of the ground and the soil conditioning parameters to be used. INTRODUCTION Phase 1 of the Doha Metro Underground project is composed by 3 lines able to bring passengers to all the points of interest in the Qatar capital city. The Red Line, also called coastal line, connects the north of the city to the south, and to the new Hamad International Airport, following the coast line. The Golden Line, called Historic Line, will connect the southern area of Doha to the “Aspire zone” the area of the city where many state of the art sport centers are located, passing through the old city center. The Green Line, named education line, will connect the old city center to the Doha Education City. All the lines are realized with 2 tubes, single track. The whole underground project is realized with 21 TBMs, excavation diameter of 7.10 m. The project has been divided in 4 packages, for a total excavation length of more than 100 km. The need to underpass roads, existing buildings, and to excavate, in some areas, at less than 100 m from the coast line, forced the choice of a tunneling system with Earth Pressure Balance (EPB), that involves in the project another fundamental aspect of this tunneling system: the soil conditioning. The soil conditioning has multiples functions in the EPB system such as to make the soil suitable to properly apply the pressure on the tunnel face and to be extracted effectively with the screw conveyor. To properly study this topic it was necessary to study the geological formations to be excavated, the hydrogeological conditions of the underground, the foam injection systems of the EPB TBMs and to perform specific tests to evaluate a suitable conditioning to be verified and adjusted during the real scale application."

Jan 1, 2016

By Colin Connors

Cemented rockfill is a key component in the success of underground mining at the Jerritt Canyon Joint Venture. The Murray and SSX mines are characterized by relatively poor rock mass quality, and the goal of complete mining recovery makes maintaining a high quality backfill product vital to the safety and efficiency of the mining operations. A large portion of the ore production from the Murray mine originates from drifting under backfill. Modelling studies performed to investigate induced loading of the backfill were used to develop engineering specifications for the backfill material. Operations history has shown an almost 100 percent stability of the backfill when mining is carried out beneath it. The volume of backfill required each year (approximately 300,000 tons) and the required cement content have a significant impact on the total mining costs. The potential for cost savings associated with higher replacement of cement with Type "C" fly ash and the implementation of a backfill strength management strategy were therefore evaluated.

Jan 1, 2001

By S. B. Patton, T. Novak

To fully utilize a ventilation simulator as a planning and production tool, the network database must keep pace with mining progress. By using AutoCAD&apos;s™ attribute-definition function, the branch data and node coordinates can be stored as part of the branch-diagram file and updated with the drawing. Attributes are drawing entities that contain text which can he extracted in a standard spreadsheet format or as an ASCII text file. The data can be subsequently loaded into a ventilation simulator. This paper presents the methodology for using AutoCAD&apos;s™ attribute feature in a ventilation simulation format.

Jan 1, 1995

By J. P. Rider

Along with increased production from longwall units has come the likelihood of increased worker noise exposures. In recent years, equipment has become larger, more powerful, and noisier than its predecessors. For these reasons, the Mining Division of the National Institute for Occupational Safety and Health (NIOSH) is investigating worker noise exposure on longwall faces and researching possible solutions to reduce this exposure. Part of this research effort involves studying the effect of covering the underside of longwall shields with acoustical material to reduce reverberating noise along the face. Experiments using acoustical absorptive insulation to cover the undersides of the shields, shearer body, and the shield supports were conducted at the full scale simulated longwall test facility located at the Pittsburgh Research Center. Sound levels were recorded every l.5 m [5 ft] along a 15.2 m [50 ft] section of the simulated face for all of the conditions tested. The analysis of the data indicated that a 2.0-3.0 dBA noise reduction was achieved between the shearer drums and a 4.0-5.5 dBA attenuation was attained upwind of the headgate drum.

Jan 1, 1997

By M. L. Leming

The mechanisms of Alkali-Silica Reactivity (ASR) are briefly reviewed, test methods are examined, and typical specifications are discussed. In addition, views on responsibility of the aggregate supplier regarding specifications are presented.

Jan 1, 1995

By João F. C. L. Costa, Vanessa C. Koppe, Clayton V. Deutsch, Marcel A. A. Bassani, Pedro H. A. Campos

Blending inevitably occurs to some degree during mining and mineral processing operations. Traditional mine scheduling assumes that all variables average linearly, which allows the calculation of the blended material properties as a linear weighted average. However, metallurgical properties such as metal recovery and Bond Work Index (BWI) are known to average nonlinearly. The nonlinear properties of the blended material can be calculated using nonlinear blending models. A simulated annealing algorithm is developed and applied to a short‐term mining face optimization problem to maximize the total metal recovered considering nonlinear blending. Compared to a standard schedule plan, the optimized one shows relevant improvements in synergistic and antagonistic blending behaviors.

Jun 25, 2023

By D. Suarez

The work of engineers responsible for the design and performance of mine facilities is often challenged by economic and practical constraints in the field. Problems have developed in implementing design criteria dictated by persons or agencies not familiar with the dynamic nature of mine engineering. Regional and site-specific conditions frequently require changes to standard designs, or the use of a completely innovative approach, which is not provided for in the regulations. The implementation of engineering design, therefore, usually requires a hard-sell approach to management and regulatory agencies that allows for a happy-medium to all parties concerned. Flexibility on the part of the regulatory agencies is needed to solve operational and environmental problems with sound engineering. Typical hydrologic issues which will be discussed fall in the following general categories: ? Design criteria for sizing water control structures (i.e., culverts, diversion and sedimentation ponds, ditches, etc.) ? Implementation (construction and operation) difficulties ? Regulatory compliance ? Reclamation planning with hydrologic considerations ? Protection of groundwater resources

Jan 1, 1986

By William P. Walsh

In December 1983 the author undertook an investigation in east Texas which was organized to learn the feasibility of applying geophysical techniques over shallow lignite deposits. The work embraced experimental high resolution seismic reflection and offset Wenner resisitivity sounds over three 4 to 4 mile test sections. This site also was sponsored by Woodward-Clyde Consultants (WCC) and a consortium headed by North American Coal Corporation. The principal objective of this investigation was to learn whether the aforementioned geophysical techniques could be applied over shallow lignite deposits (i.e. located at approximately 100&apos; to 300&apos; in depth) and consequently provide structural and stratigraphic information useful for resource and reserve characterization. A secondary objective was to determine if these same techniques could disclose the nature of the overburden and the distribution of ground water therein.

Jan 1, 1985

By S. C. Libby

The amount of fine material (minus 60 Tyler mesh) generated during calcination and/or handling of calcined abrasive grade bauxite from Alcoa&apos;s operations at Moengo, Suriname, has recently increased relative to past production experience. Bulk samples of raw abrasive grade bauxite from three deposits in the Moengo area have been studied in order to determine the factors controlling the generation of fine material samples from the Jones IC and Tapira deposits, which generate excessive amounts of fine material, have been compared with reference samples from the Begi Gado deposit, which does not generate excessive fine material. Additional type samples of abrasive grade and marginal abrasive grade bauxite from deposits in the Moengo area which represent different bauxite textures found in the Jones IC, Jones I, and Begi Gado deposits have also been studied. Field observations in the Moengo area have indicated that abrasive grade bauxites with a dull, earthy appearance generally do not generate excessive fines. On the other hand, excessive fines are generally associated with coarsely crystalline bauxite in which the gibbsite crystals appear to sparkle in sunlight.

Jan 1, 1980

By Atsushi Sainoki

Induced seismicity is deeply related to various engineering projects entailing anthropogenic in-situ stress change in deep underground. Hence, there is a persistent demand for estimating and mitigating the risk. Significant efforts have been made in simulating induced seismicity with a variety of numerical simulation techniques; however, there are still discrepancies between characteristics of induced seismicity numerically simulated and observed in the field. One of such discrepancies is the simulation of triggered seismicity defined as seismic events caused by an infinitesimal amount of anthropogenic stress change, which is frequently observed in geological structures. The present study aims to develop a methodology to simulate triggered seismicity whilst reproducing a complex stress state in a fault zone. For the purpose, a discrete fracture network within a fault damage zone is first generated. Then, an equivalent continuum model, in which each zone has a different anisotropic compliance tensor, is constructed by employing the crack tensor theory. A fault core is simulated at the center of the model with interface elements. Using the equivalent continuum model, an initial stress condition is simulated with the boundary traction method, which results in a very complex stress state with stress anomalies due to the stiffness anisotropy and heterogeneity. Subsequently, the effective normal stress on the fault plane is decreased in a stepwise manner to induce slip. The result demonstrated that many seismic events are induced on the fault plane with a slight decrease in the confining stress, thus being regarded as triggered seismic event. Further analysis on this seismic activity shows that the magnitude of triggered seismic events is inconsistent with the amount of shear stress drop, implying that a relatively small triggered seismic event could produce a large stress drop, generating locally intense ground motions and thus inducing severe damage to the nearby rock mass.

Apr 26, 2022