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By M. E. Poad, W. G. Pariseau, M. A. Laurenti

In 1986, a cooperative effort by Homestake Mining Co., the US Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high-grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will he safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modeling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1996

By M. David Monroe

Getting the best match between truck and haul road requires examining the cost effects of many factors. Most mines use a bottom line measure based on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. For specific tasks, productivity can be measured or predicted using either field measurement or modeling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture. Factors are time- and task-oriented and can be influenced by a summation of factors over a truck's lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods. Items such as fuel and tires can be tied more directly to certain tasks. This article focuses on the more direct, task-oriented factors that affect truck productivity and cost. Major factors The relationship of haul roads and trucks means that each must be examined separately to isolate the most important factors affecting performance and cost. There are many factors but the most important are:

Jan 1, 1992

By Joel Lenz, Warren Hood, Jackson Jenkins

Whole ore or other process streams are being transported from mines to remote processing facilities for multiple reasons, such as improved project economics, maximum utilization of capital, and minimization of environmental risk. Case studies will be presented from a variety of operations. Glenbrook Nickel processes ore from their deposit and receives ore from New Caledonia, crushes and dries the ore, and transports it inland to the smelter. The Mule Canyon and Rosebud ore bodies truck-haul their ores to the Lone Tree and Twin Creeks processing plants. Pegasus Gold hauls their Diamond Hill ore to their Montana Tunnels facilities, and Sierrita pumps solution to an existing tank house 8 miles away for electrolytic recovery.

Jan 1, 1998

By Y. A. Attia, D. K. Sengupta, H. A. Hamza

Increased recycling of waste paper has been emphasized in recent years in both the United States and Canada for environmental and economic reasons. Removal of ink particles from waste paper pulp is therefore necessary. One of the most promising methods for ink removal is froth flotation. This study investigated the feasibility of a simplified flotation scheme and found that about 90% to 92% ink removal can be achieved. Also, a 95% to 97% ink removal is achievable if a hydrophobic polymer is used ahead of the flotation stage. Clean paper pulp recovery was over 90%. The effects of pulping pH, flotation pH and concentrations of flotation and polymeric reagents are discussed in the paper.

Jan 1, 1995

By Abdellah Chlk, Driss Msatef

Sedimentary phosphate ores are known for their relatively high specific surface area and porosity, which have a positive influence on their reactivity when used as fertilizer in acidic soils or in the manufacture of wet phosphoric acid and phosphatic fertilizers. However, these physical properties could have a negative effect on the behavior of these ores if dried. This effect has been studied on several phosphate ores samples by: the determination of mineralogical and textural properties of these samples, the determination of vapor water sorption isotherms, at different temperatures, from which the sorption heat has been calculated, carrying out several drying tests using a laboratory fluidized bed reactor under constant conditions, which showed important differences in drying rates and residual moistures.

Jan 1, 1999

By M. J. Hrebar

A study was conducted to evaluate the applicability of large wheel loaders (Caterpillar 994 Class) for use as primary loading equipment in open-pit iron-ore operations. Field visits were made to taconite and gold mines that used large wheel loaders. Information was gathered on loader selection rationale; operation and maintenance experience; and production, availability and costs. Brief time studies were conducted to indicate machine performance and utilization. This paper summarizes the field data that was collected, including an economic comparison of wheel loaders and cable shovels in an iron-ore application.

Jan 1, 1998

By B Faulkner, M. Weinecke

In 1997, Sveciala began a program to develop a process to convert waste tires into valuable commodities. A review of numerous approaches revealed shortcomings that were process related or mechanical related, while some of the approaches emphasized he production of low-value products. A market study revealed that a process that could produce a good grade of carbon black would be economically feasible. This paper discusses the laboratory and pilot-plant development and commercial plant design of such a process.

Jan 1, 2002

By Jaroslaw Drelich

This report briefly reviews the measurements and interpretation of adhesion forces measured between microscopic probes and substrates having micro- and nanoscaled roughness characteristics that were recently conducted at Michigan Tech using atomic force microscopy. The laboratory study concentrated on both rigid and deformable materials, with the probes larger than the size of roughness features of interacting surfaces. For such systems, a detailed surface characterization in terms of roughness parameters, asperity size and shape, and spacing between asperities, as well as analysis of deformation of materials is required. Analysis of the experimental data can be done with theoretical models, which are suitable for rough surfaces and therefore allows to normalize the measured forces. Alternatively, loading of the probe during adhesion force measurements can be managed properly to control deformations of the nano-scaled surface irregularities. Controlling the deformation reduces and even eliminates the effects of nano-roughness on the probesubstrate contact area, promoting conditions described by the contact mechanics models for the sphere-smooth substrate system.

Jan 1, 2005

By J. A. Herbst, A. E. Oblad, Y. C. Lo

The major cost in comminution is energy consumption, which can be as high as 50% of the operating cost. Improvements in plant operations have resulted in up to a 15% reduction in energy usage (kw-hr/t). These improvements have been made through the optimization of grinding efficiency and the use of expert model-based control systems. Optimization involves the determination of the levels of the critical-operating conditions that result in the most efficient breakage of ore in the mill. These optimal levels are identified through plant/laboratory test work and through computer simulation using advanced process models. Model-based expert control achieves the maximum performance from the grinding circuit by identifying the characteristics of the ore in the mill with an optimal on-line estimator. Using this information, the control system dynamically determines the operating point that will yield the optimal performance. Two industrial applications of grinding-circuit optimization and model-based control are presented to demonstrate the power of this new technology.

Jan 1, 1997

By Bruce B. Redpath

Single-charge cratering tests can provide a direct measure of the powder factor necessary for achieving a desired effect in conventional blasting. If a desired blast effect, such as fragmentation or mound velocity, is produced by a single point-charge at a particular scaled depth of burial, then the cube of the reciprocal of that scaled depth is the appropriate powder factor for duplicating the effect in a conventional array of blast holes. Scaling formulas are presented that provide a link between point-, line- and plane-charge geometries, and which can be Apparent crater used for blast design. Mound and burden velocities from several sources are compared and several examples of blast design are given.

Jan 1, 1977

By J. D. Miller, C. L. Lin

A PC, image-based, on-line instrument for measuring coarse particle size on a conveyor belt is under development. The hardware and software required to implement such a system are discussed, including the interface for the special image-acquisition hardware. The system concept is given with examples to illustrate the step-by-step procedure for the implementation of image-processing algorithms.

Jan 1, 1994

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By R. Hogg, T. F. Dumm

A simple shape description scheme has been developed which has the specific aim of distinguishing between angular and more rounded particles. The procedure involves fitting a general polygon (usually about 20 sided) to the particle profile. Geometric shape descriptors have been defined based on variations in the angles between adjacent sides and their radial displacement from the particle centroid. A two-parameter shape description, incorporating an angular variabli1ity and an elongation index, has been shown to be clearly consistent with visual observations. A single-parameter angularity index has been shown to be very sensitive to small differences in particle roundness and seems to provide a better description of angularity than other approaches such as signature and fractal analyses. The scheme has been applied to three sets of fine quartz particles produced by different grinding procedures. The results indicate that the technique is capable of distinguishing between angular and re1atively rounded particles and can quantify their specific shape features.

Jan 1, 1991

By Gary S. Brierley, Ronald E. Romley, Alan L. Howard

The Price Road Drain Tunnel in Tempe, Arizona is part of the drainage system constructed in conjunction with the Outer Loop Highway in metropolitan Phoenix. The Outer Loop Project is a part of a much larger expressway system that includes other large drainage tunnels such as the Papago Freeway Drain Tunnels. Large diameter downhole inspection borings were utilized to obtain subsurface data for the design of these tunnels. Subsurface data obtained from the large diameter borings resulted in the development of empirical parameters that were successfully incorporated into the Geotechnical Design Summary Report and which satisfactorily predicted ground behavior, formed the basis for improved geotechnical design criteria, and facilitated the cost effective assessment of third party risk. The purpose of this paper is to describe the subsurface exploration program performed for this project and to explain the methods used to evaluate underground construction procedures.

Jan 1, 1991

By James Wm. White

Mine management now recognizes the value of computer-based truck-shovel dispatching in open pit mines. The key tangible benefits are substantial productivity increases with a given fleet of equipment or, alternately, significant reductions in equipment required to meet production quotas. In this work, we review the literature, report on efficient, optimal algorithms for haul truck dispatching in real-time, and briefly discuss methods used by various mines to evaluate productivity improvements over manual methods. We also present actual results obtained at thirteen mining operations around the world.

Jan 1, 1992

By I. S. Parrish

Gold deposits in Hebei and Shanxi provinces in northeast China fall into three general classes: - Placer deposits - Mesothermal vein deposits - Disseminated and oxidized volcanogenic deposits Past production dating back thousands of years has all but exhausted the placers. The mesothermal vein deposits, incorrectly considered in the past as "greenstone" type, are small to moderate in both size and grade. Production from these granulite and amphibolite hosted veins, at present greater than from the newly discovered disseminated deposits, is expected to wane. Production from the disseminated deposits achieved only in the past few years is expected to equal or surpass that from the other classes of deposits. At least one "world-class" deposit is being developed.

Jan 1, 1989

By Jerry Peterson

Mine maintenance planning, scheduling and daily workflow communications are crucial elements for enhancing overall efficiency and reducing costs. Equally important, it helps identify time periods that equipment will be unavailable so conflicts with production demands are avoided. The current CMMS Kennecott Energy Corporation (KEC) utilizes does not perform these functions in an effective manner. A solution to this problem was to develop an intuitive web-based maintenance planning, scheduling and work flow system call E-MESA. This paper will discuss the E-MESA'S system structure and advantages and disadvantages of using the web based E-MESA solution to perform the maintenance functions described above.

Jan 1, 2002

By Guido Deissnann, Jennifer L. Kirkaldy, Stephan Kistinger, Carol M. Pettit

Contaminated mine drainage presents a potential hazard for aquatic ecosystems and groundwater resources. Reliable predictions of long-term developments in seepage quality are necessary to select reasonable decommissioning options and remediation measures for waste-rock heaps during mine closure and/or mining site rehabilitation to minimize future risks and environmental hazards. Extensive geochemical modeling work was used to assess the consequences of various remediation options for waste rock heaps at a former uranium mine in Eastern Germany. The predicted contaminant discharges are used for an assessment of long- term benefits of decommissioning alternatives to derive conclusions for sustainable remediation measures using risk-based cost/benefit analyses.

Jan 1, 2000

By Wiston Rocher

The Minera Ojos Del Salado (MINOSAL) concentrator is located 20 km (12 miles) southeast of Copiapo, Chile. It processes copper ore provided by its Santos and Resguardo mines at a capacity of 4.2 kt/d (4620 stpd). In 1982, Phelps Dodge acquired the majority interest in MINOSAL to explore the property's potential. At that time, the concentrator plant was a small, antiquated installation with a capacity of 674 t/d (740 stpd). At the time of the pur¬chase, the majority of the ore was produced from the Santos and Resguardo mines, but custom ores of copper, silver and gold were also treated. The acquisition occurred at a crucial time in the copper business, since the price had fallen to nearly 50 cents/ lb. In 1985, Phelps Dodge purchased the outstanding interest in MINOSAL and acquired 100% of the property. Today, after numerous improvements and two expansions, the concentrator is a combination of old and new equipment. The regrind mills, for example, have been in service for about 50 years, while the ceramic concentrate filter represents the latest technology.

Jan 1, 1993

By Fred D. Wright

In this paper the principal theories used to design roof bolting systems are presented and discussed. Then the characteristics of various types of roof bolts are presented and finally the interaction between rock and roof bolt characteristics on choice of roof bolts is discussed. Theories can be considered design tools which may or may not be appropriate for a specific situation. It is good for a design engineer to have a number of such tools available and also important that he understand their good features as well as their limitations. Hence, some of the principal theories and classification systems used for design of roof bolting systems are discussed first.

Jan 1, 1982