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By R. A. Halatchev

Historically two basic approaches of production sequencing have been formed in the theory of open pit mine design. The first approach implements a technological discretization of the pit space within the ultimate pit outlines where the minimum working width is the limiting technological factor. The second approach uses a pseudo-economic discretization based on the implementation of analytical methods for designing intermediate/ultimate pit outlines and the concept of pit shells generation. The paper offers an elaborate analysis of both approaches used currently for discretization of the geological medium into working benches and modelling the working zone of open pit mine. The analysis is extended with a new vision for unification of the mining systems in open pit mine design under the form of a classification. A comparison of the approaches is provided to illustrate their advantages and disadvantages with regard to the implementation of the principle of waste deferment as one of the main principles of mine planning that exploits the time effect of money.

Jan 1, 2003

By Charles H. Arnold, Timothy Fallara, David A. Day, Paul H. Marshall

The Upper Scioto West Interceptor Sewer (USWIS), Parts 1 and 2, consists of approximately 7,128 meters (23,385 ft) of 328 cm (129 in.) diameter tunnel. The project ex-tends from the City of Dublin to Griggs Dam in the City of Columbus. The majority of the tunnel was designed for excavation in rock by TBM. The remaining portions span pre-glaciation formed valleys in-filled with glacially-derived sediments. Tunnel construction in one of the glacial till filled sections includes excavation by drilling and controlled blasting. The other section will be constructed by ground consolidation followed by excavation by TBM. This paper describes the methods employed to mine the glacial till filled valleys.

Jan 1, 1997

By R. K. Amankwah, E. K. Asiam

Changes in the thermal-oxidation behavior and other properties of gold-bearing waste activated carbon when milled in both a ball mill and a vibratory mill were investigated. It was found that significant changes occurred in the oxidation temperature of the vibration-milled waste carbon as a result of increases in surface area and mechano-chemical activation. The mechano-chemical action brought about modifications in the crystal structure of the waste carbon. As a result, the vibration-milled sample was completely oxidized at a temperature of 450°C. Thus, the study established that vibration milling is a better way of lowering the temperature of oxidation of the waste carbon. Furthermore, the gold was found to be concentrated in the ash and, when leached with cyanide for 20 hrs, the gold recoveries from a sample having a head grade of 2 kg/t was 99.5% for the vibration-milled sample and 82% for the ball-milled sample. The lower gold recovery for the ball-milled sample was attributed to sintering of the ash, which was caused by the higher temperature required for its oxidation.

Jan 1, 1997

By Alfred Jr. Petrick, William A. Vogely

INTRODUCTION The scope of mineral finance extends beyond the economic aspects of property evaluation to all of those activities involving acquisition and utilization of funds with an objective to optimize the value of the firm. It must, therefore, en- compass consideration of the overall financial goals of the firm, decisions involving external versus internal growth and domestic versus foreign investments, management of working cap- ital, efforts to minimize the cost of capital, and decisions with regards to the instruments of long- term debt and equity financing. The scope of this section is limited to considerations of special interest to the mineral or petroleum engineer, which include the following aspects of mineral finance: (1) The technical aspects of mineral or coal property or oil and gas reservoir evaluation which provide the basis for estimation and forecasting of revenues and costs. (2) Estimation and forecasting of costs and prices in a inflationary economic environment. (3) Calculation of cash flows which model .. , the investment in minerals, coal or oil, and gas. Such models require assumptions as to the timing of cash flows, escalation of capital and operating costs, base prices, and escalation, the tax regime, royalties, division of profits and the economic aspects of loans. (4) The role of discount rate in the economic analysis of an investment which requires consideration of the opportunity costs of the firm, cost of capital, risk premiums. (5) Risk analysis including application of the concepts of conditional net present value, expected value, and risk preference as well as the application of the techniques of sensitivity and simulation. (6) Selection of application criteria for in- vestment decision making. (7) Capital structure with particular reference to the effect of debt financing. (8) Consideration of sources of funds utilized by the minerals industries. (9) Long-range planning including portfolio analysis. This section is limited to principles, methodologies, and trends in mineral investment, finance, and long-range planning in the United States with a perspective from the year 1984. Consideration of the key concepts is supplemented by case examples of investment risk analysis and financial structure. Important factors affecting mineral investment evaluation during the 1980s include volatile metals prices, cost inflation, and the introduction of techniques requiring the computer and its capacity for improved technical and economic analysis into the hands of those who know most about the industry. The personal computer is replacing the calculator on the desk of the individual analyst and is rapidly becoming a required tool for the study of engineering and economics. Examples of change brought about by the micro-computer include greatly improved techniques of cost estimation, wider application of the computer for project analysis, computer graphics, reserve estimation, geostatistical analysis, mine design and other techniques that capitalize on the ability of the computer to handle

Jan 1, 1985

By Maria S. Adusmilli, Bhaskara A. Rao, Jorge G. C. Barros, Augusto F. Mendonca

Lateritic gold has been the object of study only for a very few years, though nuggets have been mentioned in earlier works even as early as 1984 by Hartt in Brazil. In Mato Grosso State, lateritisation is intense, as is common in all tropical forest areas of the world. Exploration has revealed the presence of recoverable "nugget gold" of variable sizes (30 - 200 gms) but frequently of good size (0 - 40 gms), especially near Cuiaba and Alta Floresta regions. In both of them the host system is a lateritised breccia indicative of a fault or shear zone breccia, though in different lithological domains. The Cuiaba occurrences are phyllitic and show a profile as follows, from top to bottom: 1) Compact ferralite crust. 2) Oolitic to pisolitic compact crust (+ some gold). 3) Mottled concretionary laterite crust. 4) Lateritised "eluvial material" (gold nuggets). 5) Mottled patchy to banded laterite. 6) Banded lateritised phyllite with lenticular to banded goethite. 7) Altered red goethitic phyllite, with quartz veins (+ fine gold). 8) Unaltered grey phyllite with quartz veins (Protore). The Alta Floresta-Juruena River occurrences are volcano-sedimentary and show a profile as follows: 1) Deep brown siltitic, argillaceous and arenaceous material with organic matter (+ gold). 2) Modular and concretionary laterite, compact and indurated, with arsenophyrite in quartz fragments (gold nuggets). 3) Band with silty-clayey matrix and arenaceous in nature. 4) Bedrock meta-arcosian arenite. 5) Volcano-sedimentary with rhyodacites and andesitic basalts, with intercalations of arkosic and greywacke nature. Breccias and quartz veins, and granites associated in different portions (Protore).

Jan 1, 1988

By D. Ince

Flotation of dolomite from apatite was investigated, using dodecylamine hydrochloride or sodium oleate as the collector, with and without inorganic modifiers such as sodium chloride. Separation of dolomite from apatite was anticipated from the single mineral experiments under various pH and collector concentration conditions. Flotation selectivity in the mixtures, however, was found to be limited. Attempts to control the flotation response of these minerals by addition of salts such as NaCl and KCI indicated that selectivity is possible. The presence of sodium chloride was determined to depress apatite flotation using sodium oleate, leaving dolomite flotation unaffected (Moudgil and Ince, 1989). In this paper, conditions for optimum separation and the effect of major parameters on the desired selectivity are discussed.

Jan 1, 1992

By Helmut Goehring

Surface mining has been used primarily where deposits of minerals were exposed or close to the surface. Surface mining can, therefore, be considered the oldest branch of mining. As the most accessible deposits became uneconomical because of the lack of suitable high capacity conveying systems, deep mining took its place. Only in the twentieth century was this trend reversed as high capacity production and conveying systems were developed. This rapid development was triggered by the steadily increasing demand for raw materials and fossil fuels, as well as by the ever increasing ratio between overburden and deposits.

Jan 1, 1982

By R. C. Bryan, D. B. Jamison

This paper describes a procedure for minimizing the operational costs associated with blending sodium in coal at a surface mine in the Powder River Basin. Mine site blending is performed by adjusting daily production rates for high- and low-sodium pits. These adjustments are designed to produce a consistent sodium value called the blending target. The mine's contractual limit for sodium is sufficiently close to the field average value that any decrease in the sodium blending target may result in an opportunity cost, if the number of potentially minable tons is reduced. Conversely, any increase in the blending target may result in a higher sampling cost if more information is required to keep the blend within contractual limits. Blending parameters were defined using a geostatistical block model of sodium content that was based on analyses of hundreds of in-pit sample holes. Variograms for these data were used to compute the marginal costs of opportunity and sampling for a series of hypothetical in-pit drilling patterns. These marginal costs provided a basis for selecting optimum values for key parameters such as the blending target, production variance and in-pit sampling density. The benefit of implementing these optimized parameter values is that operational costs of sodium blending will be minimized over the long-term. At the mine where this procedure was developed, each dollar spent to increase the sampling density to the optimum value was shown to generate a $10 savings in opportunity cost.

Jan 1, 1991

By Steve Lloyd, Mary Anne Antonioli, Byron Darnton

The Pegasus Gold/Montana Tunnels Mine is a high­tonnage, low-grade, base and precious metal operation in Jefferson City, Montana. Gold heads are typically 0.02 opt with the dominant gold mineral being a native metal electrum quite rich in silver. Early research and development indicated the ore to be amenable to gravity concentration at a 10 to 14 mesh grind. Although full flow gravity preconcentration was considered as a flowsheet alternative, flotation was chosen as the main recovery process due to its apparent lower cost for capital and operating. At this early juncture, the option or concept of recovering coarse free gold by gravity was deemed unnecessary or irrelevant. The intermittent loss of free gold has been observed in the flotation tailing since mill start up. A comprehensive research program was initiated in 1990 to identify the magnitude of this loss and investigate alternatives for its recovery. Batch and pilot plant testing has ultimately led to a permanent gravity circuit being installed at the cyclone underflow. The circuit is designed to scalp out the liberated coarse gold contained in the ball mill circulating load. The final flowsheet consists of: a pinched sluice to upgrade cyclone underflow; a Tyler doubledeck screen to remove over­size from sluice concentrate; Knelson concentrators for roughing and cleaning of screen undersize; an Eriez wet drum separator to remove tramp metal from Knelson concentrate; a Sweco screen to size Knelson cleaner concentrate for tabling; and a Wilfley table to produce final concentrate for direct melting.

Jan 1, 1992

By Shulin Xu, Moreno Pescara, Nicola Avagnina, Piergiorgio Grasso

The Roreto Tunnel is a shallow, twin-bore, road tunnel on the connection between the A6 and the A21 motorway in NW Italy. The challenges faced the design and construction of this tunnel derive from 1) the presence of groundwater, both phreatic and artesian; 2) excavation in loose and/or little cohesive materials; 3) excavation in cohesive materials containing water-saturated, sand lenses; and 4) surface constraints due to the urban environment. In this paper, these problems are examined and the rationale led to the optimum design choices and construction solutions explained. The experience should be useful to others when tunneling in similar situations.

Jan 1, 2003

By Feng Liu

"With seven new applications for plans of work for exploration in the international Seabed Area approved by the Council during its twentieth session of the International Seabed Authority, 26 total approvals have been made by the Council up to date. Among them, three contracts were made with COMRA. On 8 August 2014, China Minmetals Corporation submitted another application to the Authority for approval of a plan of work for exploration for polymetallic nodules in the Area, which is also sponsored by the Government of the People’s Republic of China.China is one of the main contributors to the international seabed regime. The Presentation will describe China’s activities in the Area, such as exploration, technology development, environmental protection and policy making.JIAOLONG is a submersible with capacity of 7000 meters. JIAOLONG’s sea trials were carefully made in 4 years, from 2009 through 2012 and it successfully dove to a depth of 7062m in June 2012 at Mariana trench. A so called "Test Application Phase" started thereafter, and is planned to last for 3-4 years. Two cruises and 4 legs have already been made since then. A wide-range of findings were obtained during dives in South China Sea, and in COMRA’s Exploration Contract Areas for polymetallic nodules and cobalt-rich ferromanganese crusts. This presentation will reveal the colorful findings."

Sep 1, 2014

By F. C. Schwerer, C. R. McKee, J. C. Seccombe

Production of methane from coal seams requires hydrofracturing, and the length of a hydraulic fracture determines we11 spacing. Since the volume of fluid injected is known, the fracture length is the volume divided by average width and height. If the fracture is contained in the known height of the seam, then fracture width becomes the major factor con- trolling length. Width is proportional to coal compressibility; bulk compressibility is known to be larger than intrinsic compressibility. A method is given here to measure in-situ compressibility (a) from transient pressure testing. Theory linking flow in porous media with rock mechanical properties is reviewed. A consistent derivation of the porous flow equation is given incorporating 3-D deformation and the effective stress parameter "st' linking changes in effective stress and pore pressure. The relations for "st' in terms of a and intrinsic compressibility (ai) are substituted into the field measured porosity-compressibility product (net) and solved for a, the constrained matrix compressibility. In a field example, using 4 wells with an anisotropic analysis, the ratio of major to minor permeability was 17 for the Pratt A seam. a was found to be 6x10-5/psi as opposed to the laboratory value of 1.4x10-6/psi.

Jan 1, 1986

By Scott G. Britton

Until now, only the range of typical construction projects which are repeated over and over during the life of a coal mine have been discussed. This chapter looks at underground construction projects which occur only once or twice during the life of any given mine and are major construction projects in both time and cost. These projects usually require the services of an outside engineering and construction firm with hands- on experience in design installation. Because of this involvement with engineering and construction firms (EIC), the role of the construction engineer will change from one of actively de- signing and directing tasks to one of planning, inspection, and quality control. To reflect this role change in the discussions, the focus of this chapter will be changed to a broad overview of project participation. Of course, the projects under consideration in this chapter could easily fill more than one book on their design and installation. In addition, major construction projects are extremely site specific, requiring months of data collection about site geology, physical conditions, and potential excavation and construction requirements. Therefore, no attempt shall be made to discuss any detailed construction aspects as was done in earlier chapters. The purpose of this chapter is to present the fundamental concerns of a staff engineer or supervisor. This engineer does not make the decisions on choosing the EIC firm, but assists and interacts with their project team to accomplish the goals set forth by higher management. The construction topics to be reviewed fall into three main categories. The first category is highlighted by the installation of a main surge bin; the second is typified by the construction of an underground shop; and the third category encompasses special projects such as rotary dumps, crusher stations, and foremen's offices. These categories highlight the differences between degrees of mine responsibilities for project completion. The first topic is usually a turnkey project by an E/C firm for a given mine. The second topic represents the leading role of the mine in the project with a contractor as a support service or equipment supplier only. The third topic, special projects, is an example of a joint venture-between a contractor (leading partner) and mine management. These roles can change with any given project, but the changes in management responsibilities for the construction engineer can be nicely illustrated for the purposes of this text. The first step toward constructing major mine projects is to analyze the mine which influence their design. From the mine management standpoint, these parameters should reflect the role the mine will play in the project construction. In other words, what is the nature of the proposed mine environment and what are the material, labor, and time requirements needed to assist or direct the chosen engineering and construction firm? Answering these questions requires some basic project planning and cost estimation work. Here, only a general treatment is necessary, since detailed discussions of these topics will follow in Chapters 8 and 10. For those persons interested in the role of the EIC contractor, I suggest beginning by reviewing the article by Beall, "The Role of an Engineering and Construction Contractor," presented in the October 1980 issue of Mining Engineering magazine.

Jan 1, 1983

By E. Arioglu

Y. Luo and S.S. Peng are to be congratulated for their outstanding paper providing new results from surface subsidence monitoring over longwall panels under different conditions. This writer found the authors' paper very interesting. In reference to this paper, the following contributions are offered: • In the paper, the maximum possible subsidence (?Smax) induced by chain pillar convergence has been related to a parameter (h/I -p) by linear regression. (Notations are expressed in this discussion's Fig. I (b).) It is a well-known fact that in a goaf the roof lowers onto broken material that gradually compacts. Then the physical behavior of goaf may closely follow the compaction characteristics of broken materials. In light of this assumption, a mathematical means (Fig. 1(a)) of defining the expected compaction (i.e. surface subsidence) represents an exponential expression between ?Smax/m vs. h/1-p. This is based on Luo and Peng's field observations from the Appalachian, Illinois and Alabama coal fields. (The coefficient of regression "r" under consideration was computed to be 0.883). • According to Wardell's (1969) findings for board and pillar mining, the maximum possible subsidence can be expressed in terms of maximum pillar loading (depth, ratio of extraction) and the height-to-width ratio of the pillars left. Using Luo and Peng's 1991 results, this writer discovered a regression equation between the above-mentioned factors. As displayed in Fig. 1(b), the functional expression approximates as closely as possible the observed subsidence data.

Jan 1, 1992

By Q. Lin, D. Z. Wang

Molecular design plays an important role in development of new flotation reagents. Group electronegativity calculation is a main method of molecular design. It is commonly used in calculating the hydrophilic-hydrophobic balance of reagents, particularly in designing chain length of flotation reagents for located minerals. But there is a limit to group electronegativity method. The method can only apply to those of [Ø]known straight-chain compounds ([Ø] is the hydrophobic energy of each -CH2- , determined by experiment). In this Paper, we propose another new calculation method: fragment method of flotation reagent. The method could be used as a supplement of group electronegativity method to design and calculate flotation reagents without any limitation. With the fragment method, we can calculate the hydrophilic-hydrophobic performance of any known or unknown reagents including those complicate structure compounds such as cyclic, branch, heterocyclic and so on by summing the appropriate structural elements (fragment). The principle, calculation stages and some results of designing new-type flotation reagents by fragment method are presented in this paper.

Jan 1, 1995

By Matthew J. Hrebar

Dragline stripping operations account for over one-half of the U.S. bituminous coal production mined by surface coal mining methods. The dragline is a popular stripping tool because of its flexibility in varying overburden depths and relatively low operating costs per cubic yard of overburden. Because of the relatively high capital costs of the machines and their use as a primary stripping tool, the selection process is an important step in the mine planning procedure.

Jan 1, 1979

By J. P. Barbosa, R. V. V. Araújo, R. B. E. Trindade

Bromide stabilizes the auric or aurous ion by forming a stable complex in acidic aqueous solution. The oxidizing agent normally used for the process is bromine, which is a corrosive liquid with high vapour pressure. This is, in fact, the main reason why it has not found acceptance yet as an industrial oxidant for gold. Ferric ion with hydrogen peroxide and/or sodium hypochlorite have already proved to be effective oxidants for the dissolution of gold from a rotating disc in a bromide-containing aqueous solution. In the present work, preliminary tests with four selected ore samples were tested to evaluate the dissolution of gold with the same system already tested with the rotating disc (Br-/Fe3+/H2o2/NaCIO). Compared to the conventional cyanidation, results were superior in one instance only. The major obstacle seems to be the maintenance of a suitable potential to allow the complex formation. However, the studied system may be interesting, is in some situations it may yield better results than conventional cyanidation; therefore, further investigation seems to be worth doing.

Jan 1, 1995

By W. G. Pariseau

Regression analysis of calculated on measured displacements were used to assess the influence of fill and fold plunge on shaft pillar mining at the Homestake Mine. These effects were neglected in the original three-dimensional finite element analysis undertaken in 1991. An average fold plunge of 15? and a 24K fill (Young’ modulus of 24,000 psi or 165 Mpa) were used in the reanalysis. Measured displacements were obtained from an array of 36 m (120 ft) multiple-position borehole extensometers installed in June 1994 and read to March 2003. Results indicate the effects of both on calculated displacements and thus on regression parameters are noticeable. However, these neglected effects would not have changed the original inference of Ross Shaft stability during pillar mining.

Jan 1, 2004

By G. G. Marino

Little comprehensive information has been reported on the behavior of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.

Jan 1, 1989

By J. S. McEwan

This paper describes the derivation of a set of simultaneous algebraic equations that can be solved to produce a rigorous theoretical mass balance around solution mining wells. This mass balance can then be compared with a mass balance calculated from field measurements to provide the percentage of mass balance closure. Significant deviations from the closure can be an indication that the wells are either gaining or losing circulation fluids. The equations also provide calculations for the amount of water and dissolved mineral that accumulates in the well during the mining process, as well as the net mining rate. Equations for both single mineral mining and multiple mineral mining are discussed. They can easily be formatted into spread sheets for rapid calculation of field measurement data.

Jan 1, 2010