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By S. A. Shuey, E. E. Vidal, P. R. Taylor

The complex chemical make-up of electronic waste as well as the variability of feed material from post-consumer sources requires resilient processing systems that are able to handle a range of material without adversely effecting production. Several of the successful processes that are being operated by a number of large-scale metal producers are reviewed in this paper. This review outlines the processing path and final disposition of many of the important individual elemental components. Determining the chemical characteristics of processes is required to understand both metal recovery possibilities and controlling the fate of minor elements. The behavior of both the organic and metallic fractions of electronic waste during processing is evaluated thermodynamically and general conclusions are given. I

Jan 1, 2006

By Ioannis Nicolaou

This paper demonstrates the method of approach for the optimization of such filters. This does not only incorporate the proven and simple recently developed equations for the calculation of the solids throughput, the residual moisture and gas throughput, but also introduces equations for the calculation of the specific product costs for both vacuum and hyperbaric filtration under consideration of the influences exerted by the filter compressor and a possible thermal drying. An easy-to-use method is offered which incorporates a special graphic representation concerning the plotting of the target parameters in dependence of the pressure difference with which the optimal process pressure difference can be established, independent of the specific cake permeability or product fineness. Finally, the optimization method is exemplarily demonstrated for a concrete application.

Jan 1, 1995

By Fred W. Stuart

Microprocessor technology has revolutionized the business community by placing tremendous computing power in the hands of the end-user for a very inexpensive price tag. The range of applications covers process control, to office automation, to personal computing capabilities. With the influx of this new technology, which these systems have to offer, also comes some unique operational and control considerations. But before we address these items, let us lay a foundation of common terms to be used throughout this presentation. Due to the rapid advances in microprocessor technology, where a new generation of computers is announced every two or three years, it becomes difficult to define a microprocessor system and have it valid for an extended period of time! Therefore, for this presentation, we will be dealing with a subset of microprocessors called Personal Computers or PC's. At the heart of a PC is a Central Processing Unit or CPU. The CPU performs the actual program and command execution. The programs dealing with driving the various peripheral equipment is referred to as the Operating System (for example: DOS : Disk Operating System, CP/M - Control Program/Microcomputers, etc.). The CPU is normally housed in an enclosure which contains power regulators, peripheral equipment interfacing 'cards', and expansion 'slots' to enlarge the capabilities of the PC system.

Jan 1, 1989

By Peter T. Luckie, Mark S. Klima

INTRODUCTION A physical separation partitions a stream of particles into two streams - one containing a concentration of a desirable constituent; the other containing a defficiency - on the basis of a difference in physical properties. Separating ores into concentrates of increased grade and gangue minerals has been practiced for thousands of years. Physical properties of materials which have been used to achieve separations include size, relative density, shape, magnetism, surface charge, color, characteristic emission, resilience and strength. The study of physical separations has also been termed attribute tracking. The term attribute is used to describe the content of the material of interest, or, sometimes, properties not used as a basis of the separation. The content is usually given by its assay; e.g., %Cu, %Fe, etc. Attribute tracking involves material balancing. For a separation using two physical properties, say x and y, the balance is

Jan 1, 1986

By M. J. Virnig, C. P. J. Van Vuuren, A. J. Botha

The Zadra, AARL and organic elution processes and variations of them are presently widely used to recover gold from activated carbon. Despite this the study of the kinetics of elution have received relatively little attention. It is the aim of this study to investigate the rate processes taking place during elution in both inorganic and organic solutions. Batch adsorption and elution rate and equilibrium experiments were performed. The spatial concentration of gold inside carbon particles at various stages of the adsorption and elution processes were measured with a scanning electron microscope using an image analyzer to control and manage the micro-analysis data. The activated carbon particles exhibited film and intra-particle mass transfer rate- controlled behaviour during adsorption in a caustic aqueous solution at 95°C. Elutions in the aqueous caustic acetone solution at 30°C and the caustic aqueous solution at 95°C were unaffected by change in stirring rate. Elution was modelled by desorption reaction rate-control at the outer surface of the carbon particle. Adsorption and elution isotherms under duplicated solution conditions showed reasonable agreement for the inorganic solution and a large disparity for the organic solution.

Jan 1, 1993

By Steve Kral

The success of the industrial minerals end of the mining industry is often overshadowed by the high price of copper, the glamour of gold, and the nation's huge reserves of coal. Those three segments of the industry, however, along with every other business in the world, could not function without the products that are composed of a variety of industrial minerals. And, according to Haydn H. Murray, past president of SME, the value of industrial minerals in the United States is more than triple that of metals, about $19 billion a year versus $6 billion. In the developed countries of the world, he said, the value of industrial minerals is nearly always greater than the value of metallic minerals. Murray, also a professor of geology at Indiana University, was the luncheon speaker at the SME-sponsored Grinding of Industrial Minerals conference held in Asheville, NC this past September. Producers of industrial minerals know they must squeeze the maximum value out of the industrial mineral being mined and processed, Murray told the audience of about 100 people. Grinding and particle size, then, are vital to a commodity's profitability.

Jan 1, 1990

By John A. Ames

Limestone for portland cement must be beneficiated to produce uniform raw material for the kiln. Careful quarrying and selective recovery are factors in this process, but the chief aspects of beneficiation are "in plant" processes, such as crushing and screening, washing, grinding, flotation, and heavy-media separation. Numerous technical and economic problems exist. Detailed studies of the limestone deposit and the stone itself are required for intelligent beneficiation. As used in this paper, beneficiation is defined as the improving of limestone composition so as to produce an economically usable raw material A limestone deposit is defined as a mass of limestone which can be recovered, by quarrying or mining, for sale or for use in a commercially profitable operation. The stone may require elaborate processing, or it may qualify with little or none. Obviously, the "commercially profitable" qualification may change as the economy changes. Potentially commercial deposits may be of much better quality than actually developed deposits, and yet may be denied development for various economic reasons.

Jan 1, 1966

By G. H. Schnakenberg Jr.

In response to the underground mining industry's growing concern with the exposure of workers to the diesel particulate matter (DPM) component of diesel exhaust, a method was developed to estimate the average workplace concentration of DPM that could be expected from using the new lower DPMemitting engines now being approved by the US Mine Safety and Health Administration (MSHA) when these new engines are equipped with state-of-the-art exhaustcontrol technology for filtering and combusting DPM. The resulting estimate uses the MSHA-reported particulate index for these engines, the prevailing rule-of-thumb ventilation rate of 150 cfm/hp and the available diesel-exhaust filter technology that has been shown to be at least 80% effective in reducing tailpipe DPM. In the estimate calculation, every engine used in an underground mine is assumed to be equipped with this control technology. Under the stated reasonable conditions, an average DPM level of 90 µg/m3 (mass) is predicted as technically feasible.

Jan 1, 2002

By R. Schuerch, C. Cimiotti, G. Anagnostou, J. Nickerson, P. Perazzelli

"This paper presents experiences gained from the construction of the Lake Mead Intake No. 3 project. The 4.7 km long tunnel was excavated with a hybrid TBM (able to operate in both closed and open mode). The tunnel crossed metamorphic and sedimentary rocks under a hydrostatic pressure of about 14 bar. During the excavation of the tunnel the TBM encountered difficult ground conditions caused by a combination of high water pressure, poor ground quality and locally low depth of cover. The adverse conditions required the TBM to be driven in closed mode at very high support pressures (10 – 15 bar) for approximately 60% of the tunnel length. The paper summarizes the main problems encountered during TBM excavation and analyzes the evolution of the TBM parameters over the entire tunnel length. INTRODUCTION The Lake Mead Intake No. 3 project is located approximately 30 km away from the city of Las Vegas in Nevada, USA. The project consists of the construction of a deeper third intake for the biggest reservoir in the United States, which is formed by the Hoover Dam. The construction of the new intake was required due to the constant drawdown of the lake level (more than 40 m in the past 20 years) and the consequent risk that the shallower intakes 1 & 2 may run dry. The project included the fabrication and positioning on the lake bottom of an intake riser, the excavation and lining of a 185 m deep shaft and construction of a 4.7 km long tunnel. One peculiarity of the project is that the water table is located about 140 m above the tunnel elevation (i.e. corresponding to a hydrostatic pressure of 14 bar at the current lake level). The tunnel was constructed using a tunnel boring machine (TBM) able to operate in both open and closed mode (Mc Donald & Burger, 2009). The present paper focuses on the TBM tunneling experience gained from the Lake Mead Intake No. 3 tunnel. The TBM excavation started on December 27, 2011 and finished on December 10, 2014 with the breakthrough to the intake structure at the bottom of Lake Mead. GEOLOGICAL CONDITIONS The assessment of the ground conditions encountered during construction was mainly based upon qualitative descriptions of the tunnel face conditions (during open mode operations) and analysis of the extracted muck (during closed mode operations)."

Jan 1, 2016

By H. E. Rowen

I hope my title is not confusing; even more so that I am not. Actually pelletizing and sintering, meaning both the formation of pellets and the hardening of them, are closely related to each other and to phenomena of nature. Figure. 1 This many-celled porous structure, frozen as it was at the fusion temperature and was being frothed by fast-moving gases, may be considered a typical piece of sinter. The same structures have been found in natural ores.

Jan 1, 1962

By P. N. Psarropoulos

During many strong earthquakes in the past, a significant number of tailings dams failures has been recorded, leading in some cases to human life losses. However, over the last decades, seismic design of tailings dams has drawn much attention mainly due to the high environmental hazard. Although the stability of such geostructures under dynamic loading is mainly related to their liquefaction potential, there exist several technical issues that have not been adequately investigated. One of these issues is the impact of local site conditions on the dynamic earthquake stresses developed, and therefore on the inertial instability of these dams. Based on the models examined in the first part of the present study (Stability of Tailings Dams ? Part I: Static Loading), two-dimensional numerical simulations are performed in order to examine the effects of local site conditions in the dynamic response of tailings dams. Imposing dynamic loading via characteristic pulses and real earthquake records, the most commonly used types of construction methods are studied at their final stage. Emphasis is given on the special characteristics of the ground motion, while the material nonlinearity of both soil and tailings is taken into account by an equivalent-linear procedure. The results obtained indicate that local site conditions may have a significant impact on the seismic response of a tailings dam.

Jan 1, 2005

By E. Topuz, C. Patrick

Longwall face-to-face equipment transfers or moves are the largest source of nonproductive time in a long wall-mining system. Detailed planning and resourceful thinking are paramount for economical, safe and timely longwall moves. New equipment and innovative techniques are frequently tested to reduce overall more time. Determining the cost-effectiveness of these ideas is difficult since the decision is influenced by many subjective factors. A project scheduling simulation model of the longwall move process was developed to analyze and assess the economic viability of innovative transfer methods and equipment. The model provides a project-duration frequency distribution and lists of critically indexed activities and paths. It compares the monetary savings from reduced transfer time and capital costs for several ideas.

Jan 1, 1996

By Gary L. Simmons

Over the past several years, Newmont Gold Company (previously Santa Fe Pacific Gold Corporation) developed a new technology for the flotation of refractory auriferous sulfide minerals which is referred to as the N2TEC flotation process. Starting in April 1997, the first commercial flotation plant utilizing N2TEC technology was successfully commissioned at the Lone Tree Mine near Valmy, Nevada. The Lone Tree flotation plant was designed to process 4,085 mt/d of ore producing 494 mt/d of sulfide concentrate. A flotation tails leach CIP circuit was added to recover cyanide-soluble gold from the flotation tails. A portion of the flotation concentrate is blended with whole ore feed to the Lone Tree autoclave, up to the limit imposed by the current oxygen plant capacity. The remainder of the concentrate is shipped to either the Twin Creeks autoclaves or the Carlin roaster for subsequent oxidation and gold extraction. This paper discusses the results achieved in the commercial flotation plant compared to pilot plant testing and engineering design flotation modeling. Capital and operating cost information are also presented.

Jan 1, 1999

By Felicia F. Peng, Wenguang Wang

The purpose of this research work is to predict the dust concentration distributions of different particle sizes on longwall faces. This Is necessary because the dust sources must be identified before dust control techniques can be recommended and applied correctly. The dust concentration data at longwall faces were determined by using Real-time aerosol monitors (RAM-1) and gravimetric monitors. However, these field data cannot explain the nature or the mechanisms of dust flow phenomenon on longwall face. Therefore, a mathematical model Is developed taking Into account the characteristics of airflow, the natures of dust generation and particles, the mechanisms of dust transport and deposition as well as the multiple dust sources on the longwall faces. In this paper, the identification of respirable dust sources on the longwall faces are determined. The dust particle size distributions In various longwall faces are analyzed and classified. The comparison analyses of field data and model predictions are presented. Specifically, the general trends of dust concentration on the longwall faces obtained at different positions and at various conditions are discussed.

Jan 1, 1991

By L. A. Panek

A new pillar strength formula is presented. It incorporates a function [IF] of size and shape that takes into account the size-shape interaction effect as well as the enhanced strength exhibited by wide pillars. Existing pillar formulas, lacking these capabilities, are not suitable for extrapolating small-specimen test results to mine-pillar sizes and shapes. Interpreting compressive strength test results as function of [Y] reveals wide-pillar behavior in much old test data. Model relationships are discussed, along with their scaling implications.

Jan 1, 1995

By Joseph Kurtak

When prospectors discovered mineralized outcrops in Pine Creek Canyon in 1916, little did they know the site was destined to become one of the world's greatest tungsten mines. Located outside Bishop in California's rugged Sierra Nevada mountain range, the mine's development imposed unique challenges to the hardiest of mining men. In its early years, the Pine Creek operation was plagued by bad luck and poor timing. But through the perseverance of a dynamic group of mining personalities, it would gain world class status. Pine Creek tungsten supplied much of the defense needs of the United States during World War II and put the Bishop area on the map as a major contributor to the nation's stockpile of strategic metals. The mine's history was shaped by world politics, the ups and downs of metals demand and economic survival through technological innovations. In contrast to many mines, Pine Creek's workings went horizontally into and then up inside the mountains - nearly to the ridgetops. This resulted in the name "Mine in the Sky" being attached to the operation. The origin of Pine Creek's ore bodies is related to the emplacement of a portion of the Sierra Nevada batholith about 100 million years ago. During the intrusive process, granitic magmas engulfed overlying calcareous sedimentary rocks, flooding them with silica-rich hydrothermal fluids and metamorphosing them to skarn. The fluids also contained tungsten, molybdenum and copper. They precipitated as scheelite, molybdenite and chalcopyrite, respectively, during the metamorphic process. The ore-bearing skarns occur as near-vertical tabular pendants in the intrusive rocks. These were later exposed by the uplift of the Sierra Nevada mountain range and glacial erosion.

Jan 1, 1998

By Victor Phillips

The Humphrey Preparation Plant of Christopher Coal Company, located in Monongalia County, West Virginia, was built to process the combined production of the Pursglove No. 15 and the Humphrey No. 7 Mines. Both Mines operate in the Pittsburgh Seam, primarily producing Metallurgical Fuel destined for by-product ovens in the Pittsburgh District. The results of an extensive core-drilling program have established sufficient reserves of low-sulfur coal to justify a 20,000 ton-per-day preparation plant, This is the story of the preparation phase of this combined operation. Christopher Coal Company operated the Pursglove No. 15 Mine to produce steam coal, which was prepared in a conven-

Jan 1, 1958

By D. L. Passmore

The development of microcomputer software that provides an analysis of pit-specific accident and production data for the mining industry is seen as a vital component in a total loss-control system. The Mine Injury Reporting System (MIRS) allows users to access accident and production data prepared by the Health and Safety Technology Center of the Mine Safety and Health Administration of the United States Department of Labor for any particular state and to generate a simple, yet informative, report.

Jan 1, 1988

By E. Fahrenkrog

An intelligent supervisor developed using expert system tools and applied to a crushing plant is presented in this paper. The structure of this supervisor, based on a model of a human operator, consists of a Knowledge base containing a qualitative model of the process, and a Rules base with the heuristic logic used by an operator when supervising a plant. The simulation results obtained show the potential of this type of systems to supervise the automatic operation of a plant.

Jan 1, 1989

By R. F. McFarlin, H. E. El-Shall

Since its inception, the Institute of Phosphate Research has examined every promising proposal in order to find an economical, practical and environmentally sound method of dewatering phosphatic clays. The in-house development of the FIPR/DIPR process (DIPR = Dewatering Instantaneously with Pulp Recycle) would appear to answer that quest. When small amounts of fibrous materials are mixed with clay slurries and flocculent, rapid dewatering occurs. Clay solids contents of 20 to 25% can be attained by simply rolling the clay mass down an inclined screen. Higher solids (>40%) are reached by physically pressing the cake; e.g., with a belt press. Because mechanical pressing devices are too expensive for phosphatic clay treatment, FIPR has developed the "sandwich" method of simultaneously dewatering the phosphatic clays and reclaiming the mine cut, as well as a second alternate, the "median strip" proposal. Economic projections of these bench-scale alternates suggest that the FIPR/DIPR process should be no more costly than present practice, when credit is given for the simultaneous reclamation accomplished.

Jan 1, 1993