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By J. M. Rotter, R. A. Lohnes, J. Y. Ooi

Reliable prediction of wall pressures in a coal silo demands careful characterization of the stress-strain properties of the coal. This paper describes the results of triaxial compression tests on a typical fine-ground coal used in power generation and describes the fitting of several different constitutive models to the data. The fitted parameters for the constitutive models are well suited to application infinite element analyses. The different models are used to give the reader flexibility in choosing a model and to show the shortcomings of some models. To explore the quality of the fitting process, the fitted results are compared with finite element predictions of the triaxial test itself.

Jan 1, 1998

By Donald S. Skufca

This chapter focuses attention on major factors pertaining to plant design and general arrangement of equipment. Considered are efficiency of operations, coordination of maintenance and repairs, plant testing of reagents and possible future plant expansions. The design and general arrangement of equipment considers accessibility for maintenance and isolation for repairs, minimum personnel for operations and cleanup, safe working conditions with minimum interruptions to operations. The constant introduction of new reagents requires eventual plant testing and the manner of isolating a “line” or part of the facilities to allow comparisons in the testing of new reagents is discussed. As technology improves and process changes occur, additional equipment or plant expansions are inevitable. Space for these eventualities must be considered while the general arrangement drawings are in the development stages.

Jan 1, 1986

By Armando Alatorre

The Republic of México is the world's largest producer of celestite/strontium carbonate and natural sodium sulfate. It is also a significant producer of flourspar, barite, graphite, sulfur, feldspar, salt and gypsum. New production may be brought on stream for borates, wollastonite, garnet, calcium carbonate and others. The country covers a geographic area of approximately 2 million square kilometers (760,000 square miles), and is divided into seven geological/geomorphological provinces. Less than 20 percent has been explored in detail for either nonmetallic or metallic minerals. This leaves large areas available for the discovery of world-class industrial mineral deposits. In addition to new deposits of those minerals currently being produced, there is exploration and development potential for borates, magnesite, rare earths, nepheline syenite, heavy mineral sands and numerous others.

Jan 1, 1995

By Ray Soper

Important progress has been made in developing the K-Process as an alternative to cyanide as a method of recovering gold from ores and other materials.

Jan 1, 1998

By S. S. Peng

A hybrid boundary element-finite element model was formulated to model roof bolt reinforcement of the roof strata with bedding planes. This model was used to analyze the stress distribution around a rectangular opening with variables such as opening width-height ratio, number of bolts installed, number/location of bedding planes, in-situ stresses, etc. The most critical areas are identified and the number and length of roof bolt required are then determined. Two case examples are illustrated.

Jan 1, 1989

By Jean-Michel Rendu

Accurate modeling of the semivariogram is an extremely important step in the geostatistical analysis of mineral deposits. Automatic fitting of a mathematical model is often possible but not necessarily desirable. Significant geologic and statistical information must be taken into account in the fitting process, which is not always available to the computer. Manual fitting of the model is, on the other hand, extremely time consuming. Interactive graphics are best suited to optimize the process. A number of interactive methods are described, which are adapted to the modeling of semivariograms in one-, two-, or three-dimensional environments.

Jan 1, 1982

By Adam Graf

Mineral deposits are fundamentally different from most other assets -Every deposit has unique geologic and metallurgical characteristics -Asset (resource) is finite and cannot be truly replaced. -Long timeframe and time-value of reserves -Commodity price volatility (see Torries, 1998)

Jan 1, 2003

By R. S. Mateer

Linear programming on desktop computers is commonly used to optimize coal blending proportions. The objective function is usually the cost of the blend. The constraints consist of materials and heat balances as expressed as linear functions of the blend. This is illustrated in Example 1. Inclusion of a sulfur compliance constraint is more complex because the maximum permitted sulfur percentage is not a pre-specified constant. Rather, it is a function of the calorific power of the blend itself. The current limit of 1.2 pounds of sulfur dioxide per million Btu may be expressed as: Sulfur Max % = 0.6 • H/10,000 with H in Btu/lb.

Jan 1, 1994

By R M. Whyte, D McArthur, A Macintosh

In designing a gold extraction circuit utilising carbon­in-pulp (CIP) technology a number of process options can be considered. These include various combinations of leach or pre-leach, CIP or carbon-in-leach (CIL) and conventional counter-current or carousel CIP (or CIL) circuits. Factors affecting the process selection include the project's sensitivity to capital and working costs, the project life, and the mineralogy and head grade. Each process option has it's own advantages and disadvantages. This paper compares both the financial and technical aspects of the flow sheet options. The flow sheet, design aspects and operating performance of Anglogold's West Wits No. 2 and 3 Plants which are leach, pump-cell circuits are described.

Jan 1, 2000

By K. A. Prisbrey

Mineral carbonation is the reaction of carbon dioxide with mineral silicates to form solid, carbonate compounds. The carbonate ion holds carbon in a low energy state – lower than in carbon dioxide. Thus the reaction of carbon dioxide to produce mineral carbonates captures the carbon in a stable, solid form. The University of Utah is investigating the carbonation of silicate minerals by mechanochemical processing, which has the potential of being much less expensive than other methods. Tests to date have shown that a marked change takes place in the lizardite variety of serpentine after 15 to 20 minutes of intense grinding in the presence of gaseous CO2. Further testing is in progress.

Jan 1, 2004

By Dr. -Ing. Karlheinz Timtner

This paper deals with the complicated and often misunderstood relationship between torsional windup, load sharing and peak torques in conveyor backstops. The principals apply in low speed, intermediate speed or high speed applications. Once the controlling factors are understood, a reasonable approach to selection procedures can be achieved.

Jan 1, 1996

By L. B. Guo, S. S. Peng

A hybrid boundary element-finite element model was formulated to model roof-bolt reinforcement of roof strata with bedding planes. This model was used to analyze the stress distribution around a rectangular opening, with variables such as opening width-height ratio, number of bolts installed, number1 location of bedding planes, in-situ stresses, etc. The most critical areas are identified, and the number and length of roof bolt required are then determined. Two case examples are illustrated.

Jan 1, 1991

By Stephen H. E. Phillips, Michael J. Beus

A pneumatic impact breaker is used to fragment the rock at the shaft bottom, replacing the drill and blast cycle. A backhoe-type mucker removes the broken rock. The operators are in protective cabs below the bottom work deck in the shaft. Preliminary testing has been accomplished at underground and surface test sites in Arizona. Seven, approximately 6.4 m deep by 7.3 m-diameter (21 ft by 24 ft) test holes, (a total of 45 m (148 ft)), were recently excavated in various rock types, including jointed and massive quartz monzonite and rhyolite. An average advance rate of .4 m/hr (1.24 ft/hr) has been achieved. This includes breaking and mucking the rock. Further data is being sought from an in-shaft demonstration.

Jan 1, 1981

By R. L. Schmidt, Williamson. T. N.

INTRODUCTION This paper describes one of several research projects funded by the Advanced Research Projects Agency to extend the technology of rapid underground excavation. This study and field research effort are to investigate alternative means to determine rock and geological conditions in advance of a tunnel boring machine (TBM). Approximately 1 year of a planned 3-year program has resulted in the definition of three candidate drill systems. Hardware has been assembled to field test these candidates and testing has begun. The 3-year objective is to develop a single optimum prototype drill and test it in an active TBM operation. ACKNOWLEDGMENT This research was supported by the Advanced Research Projects Agency (ARPA) of the Department of Defense and was monitored by the Bureau of Mines under Contract No. H0210037. The authors and sponsoring agencies are indebted to the quarry operators in California, Virginia, and West Virginia who offered assistance including access to their properties.

Jan 1, 1997

By Jouko Suominen

The basic development of various mining equipment has been strongly influenced by two objectives; improving economic results and safety aspects. Both of these factors contribute to increased requirements of mechanization and automation in different parts of mining processes. When we are limiting the discussion the crushing circuits, automation has two dimensions, one being the component automation, or intelligence, the other being automation of complete processes. Both of these subjects are closely tied up, the former being a condition for the latter. The key technologies of crushing automation are transducers, programmable logics and computer software. Also equipment technology continually faces new challenges, which result even in totally new product families. One example of this kind of development area the track-mounted, integrated crushing systems, where design criteria have been simple control, unmanned operation, and flexibility in changing requirements. This crushing system, or philosophy, offers excellent possibilities for new concepts in various underground and open pit applications, connected with automatic process control. Following presentation is a summary of aspects, of haw a crusher manufac¬turer sees the development of automa¬tion as an integral part of equipment technology and development.

Jan 1, 1989

In the mining industry and in new and expanding fields, such as electronics, nucleonics, and astronautics, a new type of manager has evolved. The name most generally used is project manager. His business is to create a product and the principal means through which he accomplishes this is project management. In this chapter, new information is the product of the project manager; as such the products, for which the computer methods described throughout this volume are designed, fall in the domain of project management. It has been the author's experience that project management is the management tool to effectively direct the information technology function within an organization. The purpose of this chapter is to describe project management and to identify and present a solution to the problems associated with project management in the development and application of computer methods in a minerals environment. Specifically, the problems to be addressed will center around: (1) recognition of the need for project management in terms of business-environmental factors and product characteristics, (2) formulation of a method of operation in terms of organization and implementation, and (3) application of project management to the minerals industry.

Jan 1, 1979

By R. E. Weeks, D. J. Millenacker

Utilization of true in situ technologies for mining copper in Arizona will involve a complex environmental permitting process. This process is a key factor in determining the feasibility, costs, and implementing time- frames required for development of this innovative mining method. The regulatory structure in Arizona is presently changing due to enactment of the Environmental Quality Act (EQA) of 1986 and development of new aquifer protection rules and regulations. The US Bureau of Mines has reviewed the comprehensive hydrogeologic characterization, ground water monitoring, mechanical integrity testing, well construction, contingency planning, and other regulatory elements that will serve as mechanisms to assure protection of ground water resources. The purpose of this paper is to inform the domestic copper industry of the significance of the new Arizona regulatory structure and its implications for prospective in situ operators.

Jan 1, 1987

By Edward C. Dowling

The advance of science and technology influences the modern economy in countless ways. Older industries must adapt to changes in the marketplace, while new industries are born by applying new technology to meet consumer needs. In light of declining head grades and increased unit costs in the US minerals industry, new technological developments in the production environment are paramount to maintaining a competitive footing in the international marketplace. Micro-engineering research provides the transition between the knowledge base and the application of new technology on the production level. Economic considerations The primary goal of technical development in the production environment is to reduce unit operating costs. Simply stated, this is accomplished by improving operating efficiencies and productivities on the production level. The goal of micro-engineering research in the production environment is to evaluate promising technologies and develop the criteria necessary to apply them in operations. As such, this process is the first step toward innovation and discovery. Generally, the micro-engineering research is followed by macro-engineering development. In the production environment, there are generally more development projects than can be accomplished in a timely manner. Usually, this is the result of financial and human resource limitations. Consequently, it is necessary to prioritize the work such that the most beneficial projects are accomplished first. By performing a discounted cash flow analysis and using benefit-cost ratios (for non-mutually exclusive alter¬natives) or net present value criteria (for mutually exclusive alternatives), the projects can be rated from best to worst. In this way, the financial and human resources can be best allocated to first complete those projects giving the highest returns before moving on to other activities. Moreover, this information is a prerequisite for management to justify additional financial or human resources.

Jan 1, 1992

By Bart Hogeweg

The development of deep sea mineral deposits creates a new horizon for the mining industry. In a field where mining technology meets deep-water offshore engineering, new challenges are faced to come to the successful exploitation of these deposits. With the absence of proven technology for the mining of these minerals, a ?technological green field? is entered. IHC Merwede (IHC), a global market leader in the dredging and wet mining industry, is on the frontline of these developments. MTI Holland, IHC Merwede?s research and development company, has undertaken a number research efforts focused on the successful development of technology for the mining of deep sea minerals. This paper highlights a number of these efforts and illustrates IHC?s continued dedication for the research and development of technology to enable the commercial mining of deep sea minerals.

Jan 1, 2008

By R. Gerling

A computer program has been developed for finding a near-optimum schedule of the mining sequence for flat lying, tabular orebodies. The deposit is divided in blocks with equal areas and definite grades, thicknesses and ore contents. Mining is done by room and pillar method and trackless haulage to surface. Access from surface is by adits or ramps with additional vent raises. In total eight different general concepts for access and development can be realized. The optimum mining sequence is found by a heuristic method. Criterion is the maximization of the net present value over the lifetime of the mine. Specific stoping costs per t of ore are taken for con¬stant, whereas development and haulage costs for individual blocks and also sequences will be different. Correct ventilation and a technically sensible sequence are guaranteed. Beginning with a single block, neighbouring blocks are tested and an optimum stoping sequence is generated. The net present value of the total mining operation for the planning period is calculated, taking into account ore, which is mined during development. The program can also be used to investigate given mining sequences.

Jan 1, 1986