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By Malcolm Scoble, Sean Dessureault, Scott Dunbar

Budgets are key financial and behavior drivers for most businesses, including mining. Budgets are used to link strategic objectives to tactical decisions, to measure performance, and to provide basic financial planning. More accurate and pertinent budgets should result in improved strategic decision making and performance measures. This paper discusses how a process based production and cost database, based on activity based costing models and the one year production plan, can be used to create the annual budget for an operating mine as an Activity Based Budget (ABB). A case study is used to compare budgets derived from traditional methods and an ABB approach. It is evident that the ABB method is more accurate.

Jan 1, 2002

By Joseph J. Wojcik

INTRODUCTION A great deal more is involved in a sampling effort directed at a placer deposit than physically capturing a quantity of representative material and extracting the desired component. The distribution and dimensions of the sample sites must be chosen after consideration has been given to the type of deposit and the concentrating mechanism. Interpretation of the sampling results is likewise an extremely important part of the sampling program. SAMPLE SPACING The interpretation begins with the selection and design of the sampling program. A decision regarding genesis of the deposits and their geometry must be made in order to select a suitable technique and sampling pattern. Deposits differing genetically will have differing distributions and degrees of concentration.

Jan 1, 1992

By Keith G. Wallace, Justus B. Deen, Daniel J. Brunner

This paper describes the impact of natural ventilation pressure (NVP) on the Nuclear Waste Isolation Pilot Plant in New Mexico (WIPP). The WIPP site is a U.S. Department of Energy underground facility for the disposal of low level radioactive transuranic defense generated waste. Because the facility is designed for the storage of nuclear waste, special design considerations are necessary to ensure containment of potential radioactive releases. The main design considerations which influence the ventilation system are the requirements of separate air splits for mining and storage operations and of air filtering before atmospheric discharge in the event of a radioactive release. The leakage between the two air splits must always be from the mining area to the storage area. The transient effects of natural ventilation pressures, caused by seasonal and diurnal surface temperature changes, impact the ventilation characteristics throughout the facility. This paper discusses the measurements taken to quantify the changes in NVP and the engineered systems designed to mitigate against the effects of NVP.

Jan 1, 1991

By S. Ouyang

The four most important parameters controlling the flow of as in coal are the gas content, permeability, diffusion coefficient and clear characteristics. Estimates of these and, more importantly, a good knowledge about the variations in their values over time are important for proper simulation of long-term gas production. This paper describes experimental techniques for the estimation of diffusion-coefficient and permeability values, along with their time dependency under simulated in situ conditions. It is shown that the permeability and diffusion-coefficient values are not constant, as they are usually assumed to be. There is a significant variation in their values, probably as a result of changes in the microstructures of coal associated with release and flow of gas. Finally, a technique to estimate clear parameter is presented.

Jan 1, 1997

By E. Pardo-Igúzquiza

Most mining applications of geostatistical simulation are to the simulation of quantitative variables, such as grade. In many instances the occurrence of quantitative variables and the values they take are controlled, at least partially, by qualitative, or categorical, variables. Examples include quartz-vein controlled gold orebodies and stratigraphic silver/lead/zinc deposits. In these cases a realistic simulation must include geological controls on the spatial distribution of the simulated quantitative variables. This paper describes extensions to, and algorithms for, the truncated plurigausian method of simulating categorical variables. The categorical variables are modelled as indicator random functions that represent the presence/absence of the variable at spatial locations. Stochastic images of the distributions are obtained by truncation of realisations of two Gaussian random functions simulated at the same locations. Parameters required are the thresholds for truncation of the Gaussian variables and the covariance structure of each Gaussian random function. These parameters are estimated from the experimental proportions of each variable and indicator direct and cross semi-variograms. A detailed case study is shown in order to illustrate the procedure, to discuss the results and to present the algorithms for plurigaussian simulation.

Jan 1, 2002

By T. J. DeMull

AMAX's Sleeper Mine uses conventional cyanidation milling and heap leaching techniques to produce gold. Since milling operations commenced in March 1986, average ore processing rates have improved from the design rate of 455 tonnes per day to more than 720 tonnes per day. Heap leaching was added to the process facilities in September 1986 at a design rate of 1,500 tonnes per day, and current heap leaching rates exceed 2,680 tonnes per day. Presented are descriptions of the Sleeper processing facilities with emphasis on the crushing and grinding circuits, a review of the selection of crushing and grinding equipment, and a summary of operating performance during the first 16 months of operations.

Jan 1, 1988

By James Barker, Jacques Renault, Chris McKee

Previous XRD work by us (McKee, Renault, Barker; 199Oa, 1990b) showed that by using pressed powder briquettes and a peak deconvolution technique, quartz in perlite can be routinely determined at <0.1 wt. %. In the present report, we discuss two additional methods of standardization: 1) chemical determination of quartz in silicate standards and 2) addition of a large amount of quartz to an unknown mixture. The first method applies the concept of mass balance and is sensitive to the analysis of silica and a monitor element. The second minimizes mixing errors; its equation is non-linear and is derived from the two component case with unequal mass absorption coefficients treated by Klug and Alexander (1974).

Jan 1, 1991

By Finn Ouchterlony

INTRODUCTION Much of present fracture toughness testing con¬cerns chevron notched specimens (Newman Jr., 1984) since these, in principle, require neither fatigue precracking nor more registration than failure load to determine fracture toughness. Two such specimens which can be made from diamond drilled rock cores with minimal machining are the Short Rod (Barker, 1977) and the Chevron Edge Notch Round Bar in Bend¬ing or CENRBB Specimen (Ouchterlony, 1980). Even if the precracking property is especially valuable for a material like rock, practice has made the relative advantages of these chevron notched specimens much less apparent (Ouchterlony, 1982; Ouchterlony and Sun, 1983). Enough remains, however, to have the Commission on Testing Methods of the International Society for Rock Mechanics (ISRM) focus on them as standard configurations in a "Suggested Method for Determining Fracture Tough¬ness of Rock Material", which is in preparation. This paper presents material which supports the ISRM effort: 1. An experimental compliance calibration of the Chevron Bend (CENRBB or CB for short) and re¬sulting formulas. 2. Specimen tolerances, evaluation formulas, and loading rate requirements relating to both Short Rod and Chevron Bend Specimens of suggest¬ed standard proportions. 3. Some fracture toughness values obtained with the Chevron Bend Specimen. This material is mainly based on two reports (Ouchterlony, 1984 and 1985). CALIBRATION OF THE CHEVRON BEND SPECIMEN Preliminaries The specimen and basic notation is shown in Figure 1 together with a straight notched variety (SECRBB). Subscripts c and s are sometimes used below to distinguish between them. Assuming linearly elastic conditions the load point compliance [ ]

Jan 1, 1986

By J. M. King, C. J. Boggs

Acquisitions of mineral properties and companies can saddle the acquirer with unexpected and substantial liabilities and obligations incurred by the acquired or selling company that are not readily apparent from review of the company&apos;s books or files. This paper will address selected areas of concern, such as environmental and reclamation liabilities, problems of foreign ownership by the buyer or seller, pension obligations, plant closing laws, effective title review, land use and zoning.

Jan 1, 1992

By K. S. Narayanan, Marcia L. Bartges, K. S. Venkataraman

The starting powders&apos; physicochemical properties and consistency are essential for technical ceramic products to meet their performance specifications. The need for finer and more consistent powders has opened new technologies for synthesizing powders from atoms and molecules. However, submicron and near-micron powders obtained from conventional comminution and classification techniques are still competitive. This paper shows several examples from electronic ceramic applications of how we can use powder characteristics for micromanaging by design the ceramic properties such as the green and fired densities, slurry rheology, shrinkage during sintering, and the microstructure of the sintered bodies. The cross-disciplinary nature of the technology requires that the researcher not only should have a firm grip on the fundamentals of one or more disciplines, but also should be generally aware of the intricacies of other disciplines as well.

Jan 1, 1992

By Bruce H. Van Brunt, Danny L. Taylor

Estimation of local recovered tonnage and its grade above a cutoff is of paramount importance during the exploration and development stages of any mineral deposit. The spatial dis- tribution of grades as well as the cumulative distribution must be defined. In this paper, Probability Kriging, an estimator based upon rank order statistics and the estimation of the distribution of point grades within a panel, is applied to the Manhattan gold deposit. Mapping the conditional probabilities that estimated panel grades exceed a cutoff is useful to the understanding of the distribution of mineralization in a structurally controlled gold deposit.

Jan 1, 1989

By Y. Théberge, V. Svalbonas, M. Fresko, E. Stopper

For many gearing applications, calculations carried out to AGMA standards are comprehensive. For very large gears, the elastic nature of the gear and pinion structures begins to play a larger role in determining the load distribution along the teeth. Various factors affecting the stiffness of the gear and pinion sets have been studied through FEA models for actual configurations. In particular, the effect of gear shape, load location, unsymmetrical structures, etc. have been studied in the unaligned and field aligned conditions. Analysis results show that the load distribution factor is highly sensitive to pin-ion stiffness, which affects gear structure design.

Jan 1, 2004

By Patzen Wu

The Hai-Shan No. 1 Coal Mine, located in northern Taiwan, is one of the typical coal mines on the island which, limited by natural condition, are mostly small in scale. With the advancing longwall method, the mine is now winning a seam, 80 cm thick, at a 32° dip, with a working depth of 824 m below surface. The annual output is about 50,000 mt of clean coal. At the working gallery, the virgin rock temperature may go up to 46°C, difficult to be brought dam to n acceptable level: because .of the tropical climate with high intake temperature and high humidity. Besides, at this depth, the intake air that goes down the long inclined shaft generates considerable heat due to autocompression. The mine is ventilated by a set of axial-flow fan with 38 m3/S of intake air at 2.2 KPA WG. With this volume of air, the temperature at the working-face is usually above 30°C WB. Appreciable lowering of the temperature is not expected even with an increased volume of ventilated air. For this reason, decision has. been made to try the installation of a pilot underground refrigeration unit near. the lowest gate road to cool the intake. air. from 32°C WB to 28°C WB which seems acceptable to on-the-spot workers exerting heavy physical labor. The experimental unit is designed for carrying away a total heat load of 90 Kw. The capacity of the unit is 200 Kw. The unit consists of a compressor, an evaporator, a condensor and a motor. The heat rejection is done in a cooling tower. Chilled water is circulated from the evaporator to the cooler by insulated pipes. The cooler consists of 90 Kw-coils with two fans and forces air by flexible ducting onto the working face. This paper examines mainly the effect of this additional reduction of working temperature, on working efficiency of the workers. Another aspect of this experiment is to evaluate the overall economy of underground refrigeration in small-sized coal mines under tropical condition. The success of such an experiment may lead to wider application of refrigeration to render many of the deeper mines economically workable.

Jan 1, 1980

By J. W. Stevenson

The need for a separate ventilation department within the management team was recognized by the management of U. S. Pipe and Foundry before the company was purchased by Jim Walter Corporation in January, 1970. Because the coal beds of the deep underground coal properties owned by Jim Walter Resources lay 1300 to 2200 feet below the surface, efficient mine ventilation practices are essential through shaft openings varying from 16 to 22 feet in diameter. The extremely high methane gas quantity indicated to be in the coal bed because of the depth of cover and documented by various U. S. Bureau of Mines tests and demonstrated by early mining proved the need to implement this early management decision. At U. S. Pipe and Foundry mine ventilation was a function of the Mining Engineering Department with ventilation personnel assigned to the mine receiving their day to day work assignments from the mine manager or mine foreman. At Jim Walter Resources, the General Manager - Ventilation reports to the Senior Vice President, Mining Engineering, who reports directly to the President, Mining Division, Figure 1 (Company Organization Chart). Position descriptions are static; however positions are dynamic and consequently the degree of emphasis of specific duties and responsibilities change depending not only upon the aptitude of the individual performing the job but also upon his ability to meet the needs of his supervisors; and ultimately upon his ability to react to the economic forces directing our society. The following describes the duties and responsibilities of the General Manager - Ventilation, Figure 2.

Jan 1, 1980

By Robert J. Clarke

Reflections on over ten years experience handling bituminous coal from railroad cars to ground storage and lake vessels. The arrangement of the facilities is described but the basic theme of the discussion is the experience gained and lessons learned from facility operation. The Great Lakes provide the maritime environment for the economical transport of vast quantities of raw materials from their source in the Upper Lakes (the Mesabi Range, for instance) to Lower Lake Ports. Lake Erie, because of its proximity to the steel centers , blossomed with the great ports that now line its southern shore - Toledo, Sandusky, Lorain, Cleveland, Huron, Ashtabula, Conneaut and Erie.

Jan 1, 1981

By Chester A. Rowland, David M. Kjos

INTRODUCTION Mineral ore comminution is generally a feed preparation step for subsequent processing stages. Grinding, the fine product phase of comminution, requires a large capital investment and frequently is the area of maximum usage of power and wear resistant materials. Grinding is most frequently done in rotating drums utilizing loose grinding media, lifted by the rotation of the drum, to break the ores in various combinations of impact, attrition and abrasion to produce the specified product. Grinding media can be the ore itself (autogenous grinding - primary and secondary), natural or manufactured nonmetallic media (pebble milling) or manufactured metallic media - steel rods, steel or iron balls, or a combination of autogenous media and steel balls (SAG milling). This chapter covers rod and ball mills utilizing manufactured metallic grinding media. MILL DESIGN The interior surface of rod and ball mills exposed to pulp and/or grinding media are protected from wear and corrosion by rubber, metallic or a combination of rubber and metallic wear resistant materials. Rod and ball mills essentially draw constant power, thus are well suited for use of synchronous motors with power factor correction capabilities as drive motors. A net of approximately 120 to 130 percent of running torque is required to cascade the charge in these mills. The pull-in torque is about 130 to 140 percent with the pullout torque to keep the motor in-step (in-phase) generally in excess of 150 percent. When rod and ball mill are started across-the-line the starting and pull-in torques result in inrush currents exceeding 600 percent which possibly result in high voltage drops. To deliver 130 percent starting torque to the mill the motor design must take into account the maximum anticipated voltage drop. Motor torque decreases as the decimal fraction of the voltage available squared. E.g., a motor rated 160% starting torque with a 10% system voltage drop will deliver 160% x or 129.6% torque to its output shaft When it is not possible or practical to start a fully loaded synchronous motor across-the-line it is possible to utilize the motor&apos;s pull- out torque to start the mill. By using a clutch, normally an air clutch. between the motor and the mill, the motor is brought up to synchronous speed before the clutch is energized. If the motor has an adequate amount (175 or greater) of pull-out torque the pull-out torque starts the mill without major disruptions on the electrical system. Since the energy release at initial cascade of the mill charge is an inverse function of acceleration time, a minimum acceleration time of 6 to 10 seconds or more is recommended to prevent damage to the mill or the mill foundation. Economics at the time of plant design and mill purchase determine the drive to be used. The simpliest drive is the low speed synchronous motor with speeds in the range of 150 to 250 RPM connected to the mill pinionshaft by either an air clutch or flexible coupling. Using a speed reducer between the motor and pinionshaft permits using motors having speeds in the range of 600 to 1000 RPM. In this speed range, if power factor correction is not required induction motors can be used; squirrel cage where there is no restriction on inrush current; slip ring where a slow start and low inrush current is required. Air clutches can also be used to ease starting problems with squirrel cage motors. In some areas of the world induction motors and starters are less expensive than synchronous motors at a sacrifice of motor efficiency and power factor correction. Dual drives, that is two pinions driving one gear mounted on the mill, become economical for ball mills drawing more than 3500 to 4000 horsepower (2600 to 3000 kilowatts). Further developments of the low frequency, low speed synchronous motors with the rotor mounted on the mill shell or an extension of one of the mill trunnions could improve the cost picture for these "gearless drives", making them practical for large ball mills. The percent of critical speed, which is the speed at which the centrifugal force is sufficiently large to cause a small particle to ad- here to the shell liners for the full revolution of the mill is given in mill specifications. Critical speed is determined from the following: Where D is mill diameter inside liners (specified in meters). Cs is critical speed in RPM. When D is specified in feet

Jan 1, 1998

By Charles G. Weakly, Alan M. Lander, Pamela B. Zohar, Robert W. Leonardson

The cluster of gold deposits at the Goldstrike property is located in the Northern Carlin Trend in northeastern Nevada (Fig. 1). At many mature mining camps like Goldstrike, exploration innovation and success may wane with time. In this regard, sufficient exploration drilling was conducted in the area immediately north of the ultimate pit crest and under the final planned pit wall to test for a major deposit. No indications of large deposits were found, however, the majority of drill holes did intercept mineralization. Mining along the northern pit wall exposed significant structurally controlled ore-grade mineralization that had been missed by exploration drilling. In 2002 and early 2003, the mine geology group added reserves to the pit and improved the definition of underground resources by targeting specific ore-controlling structures within favorable stratigraphic units by utilizing relatively inexpensive horizontal RC drilling from the pit wall. The widespread occurrence of mineralization to the north of the pit was re-interpreted to be an indication of continuity of these mineralized zones. In January 2003, 70 feet of 0.332 opt Au at a depth of 710 to 780 feet was intercepted in a dewatering well. This intercept was significantly thicker and higher-grade than average for the area, which confirmed the existence of high-grade structural continuity, and helped secure management support for additional exploration. A timely and cost effective solution was needed to confirm the potential of the area. Immediate follow-up drilling on tighter grid spacing was rejected in favor of improving the geology model. Exploration across the property would benefit from an improved geology model, but to provide results in a timely manner, the area to the north of the Betze pit was chosen as a starting point (Fig. 2).

Jan 1, 2005

By W. D. Diment

The concept of flying employees in and out of remote mine sites on a regular rotation basis, rather than establishing permanent support communities nearby, has gained increasing acceptance by mine operators, unions and regulatory agencies in Canada. The development of successful fly in/fly out programs and resultant compressed work schedules is dependent on meeting design requirements through comprehensive research of worker profiles to ensure the selection of suitable employees and the implementation of satisfactory working conditions. This paper presents an overview of Canadian mine industry practice with regard to the fly in/fly out mode of operation and compressed work schedules.

Jan 1, 1987

By Thomas H. Hibner, Daniel Tempelis, John E. Shamma

Environmental protection of nearby resources is an issue that can not be ignored in tunnel construction. The Inland Feeder Arrowhead Tunnels Project is no exception. With keen interest from various stakeholders, Metropolitan developed a Groundwater Monitoring and Mitigation Plan. This plan provides for monitoring and management of selected water resource features within the San Bernardino National Forest along the proposed tunnel alignment. The plan specifically provides for monitoring of streams, springs, seeps, and piezometers for water temperature, pH, specific conductance, and chemical analyses, as well as flow or groundwater elevation. Metropolitan uses the data to evaluate for and manage potential impacts from groundwater ingress during construction of the Arrowhead Tunnels.

Jan 1, 2003

By S. K. Kawatra, K. J. Shoop

An analysis of an iron-ore processing plant showed that its performance was affected by seasonal temperature variations, resulting in reduced grinding efficiency during the winter months. Laboratory and pilot plant studies were conducted to determine the cause of the observed loss of efficiency at lower temperatures. Two types of experiments were performed: drop tests and wet grinding tests. Drop testing was performed to determine the effect of brittleness and frozen pore water on the breakage characteristics of the ore. The wet grinding tests were divided into laboratory tumble tests and pilot-plant tests. The combined results of drop testing and wet grinding were used to make predictions on the performance of plant-scale autogenous grinding. From the drop tests, it was determined that dry iron ore, basalt and sandstone did not change in brittleness over the temperature range studied (-25º to 25ºC). However, when the rocks were water-saturated, the highly porous sandstone became considerably more fracture-resistant upon freezing, due to "grouting" of the pores and preexisting cracks by ice. This effect was not seen for either the iron ore or the basalt, because they were considerably less porous than the sandstone. Tumble tests on both laboratory and pilot scales showed that both the addition of fines to the test charge and a reduction in temperature caused a decrease in the amount of new fines produced. This reduced fines production was the result of increased slurry viscosity when either the fines content increased or the temperature decreased.

Jan 1, 1998