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The importance of factoring mining dilution into the estimation of ore reserves in an open pit mine is discussed. An example that relates the issue of mining dilution to the size of the smallest volumes that can be mined selectively is given. The relationship between the size of the selective mining units (SMUs) and the variance of their average grade is presented. The concept of variance reduction and its use in factoring mining dilution into geostatistical ore reserve estimation is described. An approach to estimate a variance reduction factor by way of conditional simulation is introduced.

Jan 1, 1998

By M. Sengupta

Vast reserves of oil shale occur in the Green River formation in Colorado, Utah, and Wyoming. The room-and-pillar mining method is applied to flat-lying sedimentary deposits. Important elements in mine design include mine orientation, vertical location of the mining zone, selection of roof horizons, room span and pillar size, barrier pillar size, panel dimension, and layout of mains and submains.

Jan 1, 1988

By K. A. Natarajan, P. Somasundaran, Namita Deo

Biological processes have recently become more attractive in hydrometallurgy and mineral processing due to their lower operating costs, potential for processing low-quality ores and flexibility. Adhesion of microbes and their metabolic products can modify the particles to render them hydrophobic or hydrophilic. Such modifications of the surface properties are used in flotation and flocculation of minerals. Microbes are also able to dissolve different precious metals from their ores. In this paper, the role of microbes and their metabolic products as surface modifying reagents in extraction processes is discussed. In addition, the ability of certain microbes to adsorb toxic metal ions or to degrade toxic chemicals discharged by industries is examined.

Jan 1, 2000

By Kevin L. Purdy

Chemical dewatering aids for mineral slurries generally fall into two classes: surfactants and flocculants, which can be used separately or together. Current industrial use of both types of reagents is summarized for sulfide and non-metallic minerals, as well as uranium and gold leach residues and coal refuse. Laboratory testing for reagent selection is briefly discussed along with reagent preparation. Chemical properties of the reagents which affect the suitability for particular applications are analyzed. [BLANK PAGES - Are in the original]

Jan 1, 1986

By Yuusaku Tominaga, Sukumar Bandopadhyay

A power-series trend curve of elapsed time was estimated by using time series data of measured concentrations of carbon monoxide in the Taiheiyo coal mine, Hokkaido, Japan. The difference between the moving average concentration data and the estimated data from the trend curve showed linear correlation when plotted on a normal probability paper and a correlation coefficient value of 0.99. It is concluded that the estimate of carbon monoxide concentration using moving average values of concentrations compares very well with the results obtained from the trend curve within the three-sigma (standard deviation) range of the distribution. Thus, it is believed the results can be used to monitor and detect abnormal ventilation conditions in a ventilation network such as the occurrence of spontaneous combustion at an early stage.

Jan 1, 2002

By P. J. Kientzler, Y. C. Lo

The current study is concerned with the analysis and attempt at simulating the product size distributions obtained from a vibrating ultrasonic device. Systematic experiments of comminution were performed with natural sizes as well as monosizes in order to understand the breakage behavior of the device. A precise analysis of the device's breakage performance in the case of fine grinding of alumina samples will be presented. Initial steps to model the breakage events using a detailed mathematical algorithm will be discussed.

Jan 1, 1992

By S. S. Nadgauda, A. J. Hathaway

Typically, as long as the coal quality is within the specified range, electric utilities have used delivered cost of fuel per million Btu as the primary criteria for qualified coals when making coal-procurement decisions. Such an approach may not fully address the total cost of using different quality coals at a given plant. A practical and easy-to-build model is described for estimating plant-specific utilization costs for coals of different qualities. Examples are included to illustrate the modeling results for plants operated by two utilities. While the model has certain limitations, it does represent an improved method for evaluating coal bids, and, consequently, reducing generation costs.

Jan 1, 1990

By R. L. Grayson, Y. J. Wang

An application of material requirements planning (MRP) to coal mine inventory control is presented. MRP is an efficient material control system that integrates the production planning and inventory management functions. Net material requirements are determined from the production forecast utilizing bill of material files, the inventory status file, and the purchase order status file. Net requirements are computed for each period in a specified planning horizon, and purchase orders, offset by lead time, are initiated routinely to ensure timely receipt of materials. The MRP system is especially useful in production-inventory systems in which con¬sumption of materials is directly production dependent.

Jan 1, 1987

By Marietta Canty

Results are presented that were gathered during field-scale testing of an innovative technology, sulfate-reducing bacteria (SRB), designed to treat and control acid mine drainage (AMD). The project was performed under the Mine Waste Technology Program (MWTP), which is funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by the EPA and the U.S. Department of Energy through an Interagency Agreement. The MWTP is implemented by MSE Technology Applications, Inc., located in Butte, Montana. A field-scale test is described in which the subsurface workings of an abandoned mine were used as an "in situ biological reactor."

Jan 1, 2000

By J. A. Muñoz, A. Ballester, C. Gómez, M. E. Sevillano, M. Figueroa

The electrochemical behavior of massive chalcopyrite (CuFeS2) electrodes has been studied in the absence and-in the presence of mesophilic microorganisms, using cyclic voltametry as analytical technique. The culture was principally formed for Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The results showed that the reactivity of the chalcopyrite gradually increased with the bacterial treatment. The anodic dissolution process of the chalcopyrite treated with microorganisms was related to the breaking of passive layers when the applied potential increased. The analysis of the surface products showed that the chalcopyrite was covered with a superficial film avoided its dissolution during the bioleaching test. So, the rest potential of the bioleached samples increased possibly as consequence of its superficial transformation.

Jan 1, 1995

By W. C. Peters

Geologists take the role of mine geologist when they apply their science to the design and operation of a specific minerals project. In doing so, they use the entire spectrum of procedures in economic geology and engineering geology to deal with a specific system of orebodies and associated environment. The objectives are established by stages in the life cycle of a mining operation as it goes from a prospect to a development project and on to a mine. This paper summarizes the elements of a mining geologist's role, with examples highlighted from the preceding papers.

Jan 1, 1992

By Arthur W. Darby

Heathrow Airport is owned and operated by BAA who are engaged in a major programme of expansion. In order to link the expansion of the airport in the west with the existing central terminal area, a twin bore, 8.8m outside diameter, road tunnel,1280m long, is being constructed. The tunnel drives pass over, with limited clearances, an operating railway tunnel, and pass under, with about one diameter cover, the airport taxiways and aircraft stands. Selection of the machine was heavily influenced by the need to minimise settlement.

Jan 1, 2003

By Richard C. Harris

Substantial economic benefits exist today for fine coal preparation and improved technologies coupled with more stringent air quality standards should increase those benefits in the future. The costs of cleaning can be determined with reasonable certainty with proper consideration given to mining methods, plant feed characteristics, refuse disposal and marketing impact. The benefits cannot be as accurately determined but include impact on generating capacity, plant maintenance, emission standards, slagging, fouling, transportation, and handling. Site specific cleaning offers particular benefits in some situations to tailor the preparation plant facility to boiler characteristics. Improved communications and methodologies need to develop to allow the coal producer and the coal user to clean coal to the degree that results in the lowest overall cost for electrical generation.

Jan 1, 1988

By C. Garcia, H. Arias, J. D. Miller, C. L. Lin

The question of ultimate recovery in heap leaching operations is always of particular concern with respect to economic considerations. Of course the particle size distribution is a critical factor which determines ultimate recovery and which must be established based on a balance between the extent of mineral exposure and transport phenomena. Now it seems that the ultimate recovery for a given particle size distribution can be established from mineral exposure analysis by x-ray microtomography (XMT). Using recently developed software, micro-CT data can be used to determine the fraction of mineral exposed and thus the ultimate recovery. Examples of mineral exposure analysis are given for the copper heap leaching operation at Zaldivar, Chile.

Jan 1, 2002

By S. P. Lucido, I. Iwasaki

The potential of controlling heavy metal ions in effluents from discontinued mining operations and waste rock piles has been investigated. A fresh water green alga, Cyanidium caldarium, was found to have the potential to remove Cut' from solutions while exhibiting high tolerance to acid conditions which are commonly encountered in copper-nickel mine drainage. The process has the potential for application as a low maintenance metal decontamination system. The growth requirements and copper removal characteristics of this microorganism are described.

Jan 1, 1991

By B. Das, D. D. Mishra, M. I. Ansari

Experiments conducted with a 75-mm-diem hydroryclone have shown it is possible to obtain an iron ore concentrate containing 60% Fe. 2.65% SiO2, and 4.0% Al2O3 from Barsua iron-ore washing-plant slimes. About 60% of the iron values are recovered from slimes containing approximately 49% Fe, 8.9% A1203 and 11% SiO2. The obtained products can be used in the sinter feed for iron and steel making. The key to achieving process success lies in establishing the correct cut point (d50) of the hydrocyclone through the manipulation of operating and design variables, such as spigot and vortex finder diameter, solids concentration and operating pressure. The cyclone efficiency is represented by the partition curve. The cyclone performance, evaluated mathematically from the reduced efficiency curve, is represented by the equation Y = 100[1 -exp(-axb)], where: •X = did 50, •Y = corrected of efficiency (%) and •a and b are constants.

Jan 1, 1994

By R. J. Pruett, P. I. Prescott

Ground calcium carbonate (GCC) is used in the paper, plastics, paint, rubber and caulks and sealants industries. The favorable properties of GCC include high whiteness and brightness, low hardness and outstanding rheology in water systems. The quality of calcitic GCC ores, which includes chalk, limestone and marble, is dependent on calcite purity and the nature and quantity of the impurity minerals. Wet and dry grinding are used in the processing of GCC. Ore processed by optical sorting, flotation and/or particle-size classification has higher brightness and lower abrasion characteristics. GCC markets are a function of the product's properties, purity and cost.

Jan 1, 1997

By Scott K. Palm

The initial intent of the Hazard Communication Standard (HCS) was to improve worker health by providing more information about the hazards of chemicals used in the workplace. However, the impact of the HCS goes well beyond worker right-to-know. There are direct costs associated with compliance. In addition, labelling and hazard communications can provide a competitive advantage to producers of minerals that have not been identified as hazardous. Often, the lack of hazardous information about a substance is due to the lack of scientific study, rather than an indication of product safety. Currently, industry and regulators sometimes give known hazards greater weight than unknown risks.

Jan 1, 1991

By Jonathan J. Owen

We will describe modifications to air-sparged hydrocyclones (ASH) that enhance collisions and reaction of wastewater contaminants with sparged gas. These new ASH-based reaction chambers are combined with flotation tanks that are designed to optimize separation of bubbles and particles from water. In combination, these systems have achieved unprecedented removal of contaminants from industrial wastewater and process water while requiring smaller footprints with lower capital and operating costs. Real-world examples of chemical and nonchemical water treatments that demonstrate the outstanding flexibility and applicability of these systems are shown. Design enhancements that resolve the operational problems of traditional ASH are discussed.

Jan 1, 1999

By K. N. Han, P. B. Queneau, Bruce W. Cavender

Measures of metallurgical performance, such as recovery rates or mass balances, are frequently based on point estimates of operating conditions in the system of interest. Because the processes being measured are dynamic, a range of uncertainty accompanies each measurement; this uncertainty is reflected in the accuracy with which the calculated result describes the true metallurgical performance. In stochastic modeling, a range of probable values is used in place of a point estimate to describe each variable. The calculated result takes the form of a distribution, delineating both the magnitude and probability of potential outcomes.

Jan 1, 1993