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By R. Addison

This is the story of the Carlton Mill. But first-a little geography. For those who do not know where the Carlton Mill is, or, perhaps, have only a vague idea, its location is indicated in Figure 1. The plant is situated on the road between the two old mining towns of Cripple Creek and Victor, 10 the west of Colorado Springs. From Denver, it's about 110 miles by road. The story of the Carlton Mill began with the discovery of gold at Cripple Creek in 1890. This discovery set off a major boom such that, by the turn of the century, there were 450 separate operating mines in the district. Gold production boomed early and declined rather rapidly as indicated by the graph in Figure 2. Significant factors affecting production are shown on the graph-the raising of the gold price in 1934 from $20.67 to $35.00 per ounce and the government executive order L-208 in 1942 requiring the closure of all gold mines.

Jan 1, 1983

By M. H. Pettibone

During the past decade, the size of grin- ding mills has steadily increased. Mills 11 m in diameter with 9 mW motors have been installed with even larger units on the drawing board. The rising costs of energy and labor have spurred interest in improving efficiency while reducing capital investment and operating labor. Autogenous and semiautogenous grinding have experienced renewed interest as efforts to reduce operating and capital costs have increased.

Jan 1, 1981

By Weiguo Xie, MARK LAPUTKA

The pyrometallurgical industry plays a vital role in producing metals for our modern life. With growing demand for metals and declining grade of mineable ore, innovations become critical for many mining companies. This has given rise to the need for a review of recent improvements to the pyrometallurgical industry in terms of analytical measurement techniques, process and equipment improvements, and computer-based modeling/simulations. Because many of these innovations tend to be applied to a wider scope of metals, not restricted to a specific metal, we studied the broad applications of many improvements to a wide range of metals. We found that the challenge of a lack of robust measurement techniques under high-temperature conditions within a furnace hinders optimization of a pyrometallurgical process. Some future opportunities in the pyrometallurgical industry on analytical measurement techniques, computer modeling, and processes and equipment were also outlined and discussed.

In its largest product launch in company history, Cummins Engines welcomed more than 200 customers, vendors and media to witness the unveiling of its new QSK95 engine at its Seymour Engine Plant in Seymour, IN on Nov. 1. It took the efforts of 150 engineers to design the QSK95 and more than $100 million in investments to establish a new production line and test facility at Cummins? Seymour Engine plant. The result of these efforts is a new platform of engines that Cummins says will provide as much as 2,983 kW (4,000 hp) and will be the most powerful, high-speed diesel engine ever built.

Jan 1, 2012

By K. S. Venkataraman

The physical properties of clay-water systems depend on the complicated system of forces between the clay particles themselves, and between the clay particles and the ions in the liquid phase. The kind and distribution of ions in, on, and between the clay particles and the size and the shape of the particles are the basic factors determining the macroscopic behavior of clay-water systems. Understanding the system requires a knowledge of the nature of the clay particles, their size, structure, composition, and surface properties, and of the manner in which they interact with ions [and molecules] in the surrounding liquid [or other medium]. The validity of Professor Brindley's words (Brindley, 1958), written three decades ago in the context of making pottery, whitewares, and electrical porcelains, transcends time, and the basic message is perhaps all the more important in the considerably expanded use of ceramics for structural, thermal, tribological, electronic, and other applications. Silicon carbide, silicon nitride, and sialons have been studied in the last two decades for high- temperature structural and tribological applications, particularly for using in internal combustion engines. Titanates, zirconates and niobates of barium, strontium and lead, have high dielectric constants, and are extensively used in the formulations for making capacitors. Hexagonal ferrites (molecular formula MO.6Fe2O3) are in use for making permanent magnets for fabricating miniature motors, and for assembling loud speakers, particle accelerators etc. Cubic ferrites such as magnesium-zinc ferrite and nickel-zinc ferrite are used as transformer cores, and for other high-frequency applications. In this context, Richerson's recent book (Richerson, 1984) on the general scope of traditional and technical ceramics is a good starting point for an overview of contemporary ceramics technology. Glasses are a whole class of amorphous materials used widely as sintering aids, and for making glass-bonded ceramics and glass-ceramic composites. Composites are yet another burgeoning field where two or more particulate components are used for improving the performance of ceramics. For all these applications, the inorganic starting materials are almost always submicron and near-micron powders. Understanding the powders' physicochemical properties, and their surface chemical interactions with the surrounding liquid/gaseous medium is-necessary for making reliable ceramic parts at competitive prices. Even though ceramics science and engineering has attained its separate identity in universities and the industry, ceramists themselves would concede that ceramics science is a cross-disciplinary field, having incorporated and assimilated within itself many principles from several apparently disjointed disciplines. Principles of material science, graduate-level physics and chemistry, polymer science, surface and colloid chemistry, transport phenomena, particle technology, unit operations commonly used in chemical engineering and mineral processing, and statistics and applied mathematics are integral part of any ceramics curriculum in universities. Added to this is the fact that all bench-scale successes in making ceramic parts are to be scaled-up for larger throughput operations. Understanding and applying process engineering principles of comminution, classification, drying, calcination, etc. then becomes essential. CERAMIC FORMING: Despite the diversity of the materials and processes, conceptually, the steps involved in making ceramic parts have remained the same over several decades: The different components for making the pan (usually one or more powders plus other forming and sintering additives) are proportioned and mixed thoroughly, and the well-mixed formulations are consolidated into desirable shapes known as "green bodies." Usually binders such as wax, clay, organic polymers and surfactants, whether dispersed or dissolved in a suitable liquid are used during mixing the batch for giving strength for the green bodies. In the dried green state, the inorganic powders typically occupy only 55 to 60% of the bulk volume of the body, depending on the particle size distributions of the powders and the forming history, with mostly inter- particle voids accounting for the rest of the void volume. SINTERING: The formed bodies are then fired in high- temperatures kilns/furnaces during which the parts are exposed to a predetermined temperature profile, and "soaked" for a certain duration at the final high temperatures, typically between 1200 K and 1900 K, and then cooled to room temperature. The gaseous atmosphere in the furnace is controlled (oxidizing, reducing, or inert) when necessary. During the initial stages of firing, volatile liquids evaporate, and during the intermediate temperatures between 400 and 600 K, the the organic polymeric additives pyrolize and oxidize into water vapor, CO, C02, and other gases. At still high temperature, the glasses, when present, soften, and simultaneously, the ceramic particles rearrange into a network of grains with definite grain boundaries so as to reduce the total interfacial free

Jan 1, 1990

By Ehsan Moradabadi, Debra F. Laefer

"To more rigorously address tunneling risks to above-ground structures, vulnerability evaluation of all structures along a tunnel route is required. This multi-block area along the route can be considered a district. To fully assess each structure within a tunnel’s zone of influence, a multi-block or district-level model may provide new insights as to risk evaluation and mitigation strategies. However populating such a model with the existing geometry of the built environment poses a major challenge as measured drawings are not readily available for all structures along a tunnel’s route. Cost-effective population of such a model could arguably involve remote sensing data in the form of laser scanning or photogramme-try. However even for unreinforced masonry structures, where external, above-ground geometries can be captured, without a prohibitively expensive building-by-building, in person survey many factors would remain unknown. To consider these uncertainties in an automatic way, a performance assess-ment framework is proposed. Such a framework allows a more rigorous, initial, risk quantification than is currently possible within the simple empirical models generally being used in industry when tunneling risk is initially assessed. This paper introduces (within the allowable space limits of this format) consider-ations for auto-population and application of a district-level, tunnel-risk screening tool. INTRODUCTION Challenging topography, intense urbanization and infrastructure development, combined with limited land availability and a growing awareness of environmental issues have lead to increasing usage of un-derground spaces to control aboveground traffic and provide essential services in metropolitan areas. Tunneling, however, is not without its own risks, especially with respect to aboveground structures whether it be widespread minor damage (Burland et al. 2001) or the more notable, although less fre-quent, large-scale collapses such as the 2003 Shanghai (Allianz 2015) or 2004 Singapore (Magnus et al. 2005) events."

Jan 1, 2016

By Grant R. Brown

The objective of this paper is to describe a study sponsored by the U.S. Department of Energy during which a model was developed to optimize haulback mining procedures in single and multiple seam contour mines, The study objective was to achieve financial- based productivity increases approaching twenty percent. This paper reviews the results of the first year's Phase I activities, which include four main tasks: formulate a methodology that can be used to select equipment and mining procedures that result in optimal performance in a particular haulback mining situation; conduct field studies of representative single and multiple seam mines to obtain quantitative background information for development of the formulated methodology: develop the methodology into a useful design tool for mine operators; and prepare plans for field tests to evaluate the effectiveness of the developed tool.

Jan 1, 1981

By S. B. Bhagwat

The United States has abundant coal resources that could last at least another century. and probably longer at present consumption rates. Geographically, the coal resources are distributed over the entire nation including Alaska, although there are no coal deposits in the highly populated areas on the two coasts. This allows free access to the coal, but makes transportation more expensive. Not all coals can be utilized equally because they differ vastly in quality. The sulfur content of coals, considered as the most detrimental acid rain-causing element, varies from as low as 0.3 percent in some areas of the western U.S. to 5 percent or more in parts of the Midwest. The chlorine content, which causes corrosion of plant hardware, also varies regionally. The 1990 amendments of the Clean Air Act of 1963 (CAA) require that emissions of sulfur be restricted and rolled back in two stages by the year 2000. There have been a number of reports expressing concern about the future of the industry in the states where high sulfur coal is produced. The remedies devised by the federal government and many coal-producing states in the past to "se-cure" the future of the regional coal industries have focused on the physical task of removing sulfur rather than the economic challenge of doing so at a cost that will enable high-sulfur coals to survive and compete. The past remedies, generally, were not specific enough to account for the characteristics of regional coal deposits and did not look at the coal market as an integrated national and international entity. The State of Illinois has, in recent years, taken a more comprehensive approach to the solution of the problem.

Jan 1, 1992

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedoms with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth". The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1979

By A. J. S. Spearing, B. Forbes, T. Kostecki, A. Hyett

Improving upon the past understanding of the interaction between installed rock bolts, the immediate roof and sidewalls is vital for the implementation of sound support system design, as this has a direct impact on rock-related safety. This is the primary goal in rock-bolt-related research. The earliest research in this field concentrated on limited laboratory and in situ measurements accompanied by theoretical analyses, based on the Kirsch equations. This represented the initial insight into understanding relative ground movements and their impact on primary support. However, these studies were far from complete. More recently, major technological advances in computing power within the mining industry has changed the scope from theoretical analysis to computer simulation. Even with these advancements our understanding of rock bolts in situ and in the laboratory has not progressed, particularly concerning bending and shear. To measure the behavior of rock bolts, the widely accepted practice is to populate the bolts with an array of strain gauges. Historically, resistive foil strain gauges or long displacement sensors have been used. Additionally, all instrumented rock bolts have used only two diametrically opposed slots. Rock bolts instrumented with these methods have significant shortcomings, one of which is the inability to capture shear and bending. The shearing and bending of rock bolts are particularly common in tabular soft rock mining, such as coal mining. This paper discusses the use of three slotted rock bolts, cut diametrically 120º apart, and two new optical fiber technologies populated along the entire rock-bolt length.

Jan 1, 2015

By Rob Herr, Irwan Halim, Heather Marsh

This project will expand sanitary sewer within the City of Columbus. It consists of 2.5 mile long, 72-inch finished diameter pipe grouted inside 10.8-foot diameter tunnel excavation in shale. This paper describes the multi-faceted geotechnical exploration to minimize the underground risks. The tunnel will cross below a buried valley with minimum cover of highly weathered rock. The risk mitigation to cross the valley includes contingencies and cost allowances. Provisions to prevent impact on adjacent groundwater resources will be described. Latest construction updates will be provided including contractor alternate shaft support and pre-excavation probing to mitigate tunneling risk below the valley.

Jun 23, 2024

By Bryan Ulrich

On March 15, 2012, about 24 attendees from several western states attended Roundtable 2012, hosted by Knight Piésold and Co. at the Red Lion Hotel and Casino in Elko, NV. The focus of this year?s discussion was ?Acid Rock Drainage for Engineers and Environmental Scientists.? Other names may have been more suitable for the event, perhaps combining geochemistry, with air and water quality and their long-term effects on soil and rock mechanics. Bryan Ulrich (senior vice president, Knight Piésold?s Nevada operations) and Steve Lange (senior geochemist, Knight Piésold, Denver, CO), helped facilitate the discussion. Attendees included personnel from a dozen mining properties, various corporate offices and academia. There were also attendees from a geochemical testing laboratory to help respond to specific questions pertaining to testing protocol and procedures.

Jan 1, 2012

By R. H. Olson

Pigments are used in two segments of papermaking, as the major component in paper coating formulations and, in small percentages, as fillers in the paper web. Historically, the dominant use has been in coating, however, recent developments have fostered a multifaceted effort to substantially increase the pigment component in the paper furnish. Factors responsible for these developments together with their relationship to recent and forecast changes in papermaking technology are reviewed. Finally, some thoughts are presented on the probable timing and extent of these changes as well as their expected impact on the future demand for the common paper pigments.

Jan 1, 1985

Several years ago, North American mining companies began to realize they needed to expand their spheres to remain viable. This strategy has been successful, according to Robert W. Schafer. Today, companies from other continents have also recognized the need for an international view for long-term growth and viability, he said. Schafer is vice president for exploration with Kinross Gold. He was the program chairman and moderator of the keynote session at the 1997 SME annual meeting, held in Denver, CO, Feb. 23-27. The theme of the meeting was "Minerals - Serving the Global Community." A record attendance of more than 6,000 people participated in the meeting, which featured 415 exhibitors occupying 582 booths. The title of the keynote session was "Corporate Perspectives on a Global Minerals Industry." Each of the three keynote speakers discussed a different perspective of a global minerals industry.

Jan 1, 1997

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal mining is likely to sustain its critical role as energy requirements are increasing. While surface mining exploits coal seams near the surface, underground mining techniques are crucial for extracting deep coal reserves. Longwall mining is one of the most common methods used in underground coal mining operations. This paper introduces a data-based framework — including data collection, data analysis and the interpretation of operational data — for understanding the system efficiency of a longwall shearer. Operational performance is evaluated by the time between arrivals (TBA) and duration of the shearer stoppages, shearer drums’ reversal time, cutting speed and flit speed on daily production in a longwall top coal caving (LTCC) mine. A discrete event simulation model is developed to represent the bidirectional cutting sequence of a longwall shearer.

By John G. Groppo, Bonnie Webb-Groppo

INTRODUCTION The first portion of this chapter is concerned primarily with the contamination aspects of fine coal cleaning that include both the solids and water discharged as waste products after coal preparation. Topics include characteristics of the water and solids, changes that occur to both of these phases during use and after impoundment, as well as the impact that these changes have on unit operations and the environment. Attention is also given to the formation of acid mine drainage and treatment options that may facilitate reuse of the water. The second part of the chapter analyzes the problem of air contaminants from coal preparation plants including analysis of air pollutants and control methods. An overview of air quality regulations is also presented; most provisions have little or no applicability to coal preparation plant operation but are presented to provide an understanding of end-user constraints. The final part of the chapter emphasizes the long-range problem of refuse disposal and control. An overview of characterization, maintenance, and control of the refuse area is presented, as well as design guidelines. A brief review of stability analysis procedures is also included. PREPARATION PLANT WATER Characteristics of Makeup Water for Coal Preparation There are few specific rules governing the quality of makeup water used in coal preparation processes.'" It is generally accepted, however, that the solid matter content should be less than 5%. The solids concentration in plant makeup water typically varies between 0.25 to 0.9 lb per gal (30 to 110 g/L) and may reach concentrations as high as 1.7 lb per gal (200 g/L). The water used in coal preparation is usually obtained from one or more of the following sources: public supplies, rivers and streams, canals, mine water, and wells. In most cases, water is obtained at the lowest cost including any necessary treatment. A major portion of the recirculated water is clarified by thickeners and settling ponds to remove fine coal and clay particles. Sufficient water is generally available to meet the needs of coal preparation in most areas. It has been estimated that approximately 65 to 70% of the makeup water used in a coal preparation plant comes from surface sources. It is important to note that a variety of substances are commonly found in natural water supplies, whatever the available source may be (Table 11-1). Excessive concentrations of some of those substances can have an affect on plant performance; the effect of specific contaminants on unit operations will be discussed

Jan 1, 1991

By Malcolm D. Flavel

Recent research into the mechanisms of crushing processes has led to the establishment of new criteria for the effective design and operation of comminution plants. This paper reviews this work and gives examples of the productivity gains and cost benefits that have been achieved in the practical application of these findings.

Jan 1, 1988

By F. G. Crack

This paper is based on the philosophy that the management structure and strategy required for mine construction and development projects are different from that required for routine production and maintenance operations in a mine. The purpose of this paper is to present an integrated approach to the management of mine development projects. This paper highlights the four major aspects of the integrated approach. First, a brief review of the various types of contract documents is provided. Second, the management organization of a project is discussed. Third, the project manager's role and the field supervisor's responsibility are briefly outlined. Finally, the use of scientific techniques for planning, scheduling, executing, and controlling projects is presented. Each of these aspects is important; however, each by itself cannot be expected to bring order or unifying impact to the complexities involved in overall project management. When all these aspects are coordinated, the result will be a sore successful project from conception to completion.

Jan 1, 1982

By Jon C. Yingling

Techniques for optimization of mineral processing flowsheets are reviewed. Though not yet widely used in the minerals industry, approaches for chemical process optimization based on successive quadratic programming (SQP) algorithms may be employed to determine optimum unit design and control settings for a mineral processing flowsheet. Moreover, in certain mineral processing flowsheet applications, specialized techniques can be applied because of the nature of the system relations. These techniques offer advanta es in efficiency. Moreover, their capability exceeds that o f the SQP approaches since simultaneous optimization of circuit configuration and unit controls can be addressed.

Jan 1, 1990

By Hugh Douglas

This paper discusses the financial health of the U.S. mining industry and its ability to meet the future raw material requirements of this country in the context of resource independence. The title of this paper begs several questions, and three will be raised here. The answers to them will form the basis for discussion. The three questions are: What does one mean by resource independence. How is the U.S. mining industry defined. How is financial health measured.

Jan 1, 1977