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By D. W. Fuerstenau

In mineral processing, the last century of the current millenium has been the century of froth flotation. The process did not result from fundamental research, but was developed over the years by empirical methods. In more recent years, our understanding of the fundamental principles of the flotation process have made significant strides. This paper reviews some of the historical perspectives of developments in flotation reagents, the development and application of experimental tools for delineating flotability and interfactial phenomena, advances in flotation fundamentals, and the development of flotation kinetics, both macroscopic and microscopic subprocesses. Through the application of surface chemistry, the flotation process has permitted economic utilization of a vast array of complex ores.

Jan 1, 1999

By Al. Valero

This paper quantifies in universal units (energy units), the annual decrease in the mineral endowment of the planet. This is done for some important extracted non-fuel minerals, namely aluminium, cobalt, chromium, copper, gold, lead, uranium and zinc and is compared with the depletion figures of conventional fossil fuels. The results of this study reveal that each year, the decrease of the global non-fuel mineral bonus provided by Nature is 2 to 3 orders of magnitude greater than the loss associated to the burning of fossil fuels. Particularly for 2008, the depletion in mineral wealth of the studied commodities was about 20 times greater than that of fossil fuels. The assessment methodology is based on the Second Law of Thermodynamics. It quantifies the useful energy (exergy) required to concentrate a mineral from a completely dispersed state in the crust, to the conditions of composition and concentration found in the mines. Exergy can be a useful measure for quantifying the mineral depletion caused by man, as it takes into account the main physical features that make minerals valuable: composition and concentration. This analysis enhances and puts numbers to the importance and necessity of material reuse and recycling.

Jan 1, 2011

By Jae-Chun Lee, Kang-In Rhee, D. B. Dreisinger, Hyo-Shin Yu, G. A. Kordosky

The development of a process for direct synthesis of very pure ZnO powders from zinc-bearing waste was investigated. The zinc waste which contains 55% zinc was leached with sulfuric acid. After iron removal by hydrolysis from this zinc solution, purification through solvent extraction by the use of D2EHPA as an extractant was carried out. Then, loaded zinc in the organic solution was stripped and precipitated simultaneously using oxalic acid as a precipitant. Synthesized ZnC2O4 precursors by precipitation stripping were calcined to obtain ZnO powders exceeding 99.9% purity. The effects of sulfuric acid concentration, leaching time, and pulp density on the extraction of zinc were studied and optimum conditions for the solvent extraction were obtained through purification of the zinc solution. The size, morphology, and size distribution of synthesized ZnC204 powders were studied in terms of oxalic acid concentration, temperature, surfactant added, precipitation time, etc.

Jan 1, 1993

By W. H. Schiffbauer

The U.S. National Institute for Occupational Safety and Health (NIOSH) developed an active proximity warning system called hazardous area signaling and ranging device (HASARD) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, which is worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels that are calibrated to identify levels of danger. The receiver outputs can include visual, audible and vibratory indicators, and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak and on a high wall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed, and it proved to be rugged enough to withstand the harshest of production environments.

Jan 1, 2003

By R. Henley, S. S. Webster, L. Harris

High resolution airborne magnetic and radiometric data have been shown to optimize exploration for epithermal gold deposits in the vicinity of Charters Towers, northeastern Queensland. The radiometric data allow extrapolation of poorly outcropping geology to provide a cost-effective mapping technique, even at exploration scales (eg. 1:25,000). At a regional scale (eg. 1 : 100,000) the magnetic data reflect the regional tectonics and divide the area into domains for the application of different genetic models. For example: 1. the Ravenswood Batholith is characterized by multiple intrusions dating from Ordovician to Permian age. The polarity of the magnetic anomalies implies an age for the intrusions and indicates a deposit style for exploration. 2. extensional and wrench tectonics along the northern margin of the Drummond Basin are interpreted from the magnetic data and indicate favourable blocks for detailed exploration. Genetic exploration models may be tested in favourable environments by the recognition of geophysical signatures. These signatures reflect structural, lithological and alteration patterns arising from controls on ore deposits and can be applied at regional or detailed scales.

Jan 1, 1989

By David A. Lindsey

In this paper, we present a physiographic classification of gravel deposits, identify some field measures of aggregate quality, and describe sampling strategies for mapping aggregate quality in the Front Range Urban Corridor of Colorado. Gravel occurs in four types of deposits along the Front Range of Colorado: (1) piedmont alluvial fans, (2) high dissected terraces, (3) high (continuous) terraces, and (4) floodplains and low terraces. The four deposit types are the basis for definition of gravel-deposit models, which differ in geologic environment, deposit characteristics, deposit size, environmental impacts of mining, and post-mining use. Of the four types, floodplains and low-terrace deposits have been exploited most for gravel. High terraces also have been mined. Deposits of high dissected terraces and dissected alluvial fans have produced minor amounts of gravel, mostly for use as local fill. Studies to identify useful field measures of aggregate quality and to determine the appropriate scale for sampling were conducted on gravel deposits beneath the flood-plain and low terraces of the South Platte River north of Denver and the Cache la Poudre River between Ft. Collins and Greeley. Gravel deposits of the South Platte were selected for study because they represent the last major resource of gravel for aggregate in the Denver metropolitan area. The Cache la Poudre valley is the primary source of gravel aggregate for rapidly urbanizing areas around Ft. Collins and Greeley. Of all the field measures of gravel quality, the most important is particle size. Various parameters that measure particle size were investigated, but the easiest to determine, and the most useful to the aggregate industry, are measures of the proportion of coarse sizes. Particle size varies widely in gravels of the urban corridor. Gravel lithology, particularly the presence of deleterious particles such as reactive volcanic rocks and decomposed rocks, must be determined to assess aggregate quality. Studies of South Platte and Cache la Poudre gravels have not revealed large proportions of deleterious lithologies. Studies of particle shape revealed only small numbers of physically weak shapes in both the South Platte and Cache la Poudre gravels. Particle shape does not appear to vary from place to place in the gravels. Rounding, or the ab¬sence of angular corners, may play a role in the tendency of loose gravel to yield under load. South Platte and Cache la Poudre gravels are rounded, and rounding tends to increase upstream. Before the quality of gravel in a valley can be assessed, the stratigraphy of the gravel must be known because it affects sample design. If only a single gravel layer is to be studied, only the thickness of the gravel must be known before sampling. If, however, more than one layer of gravel-distinguished by particle size, sorting, or lithology-is present, sampling must take into account the thickness and distribution of each layer. For example, three gravel layers of different particle size underlie the floodplain and low terraces of the South Platte. The tributary Cache la Poudre, on the other hand, contains gravel layers that can be distinguished only locally and vary slightly in particle size. Sampling experiments were conducted on gravel bars in the South Platte River and in gravel pits on the floodplain and low terraces of the South Platte and Cache la Poudre Rivers. Experimental results indicate that, even where sample error is large, regional and stratigraphic variation may be measured if it is large relative to sample error. Using vertical trench samples weighing an average of 40-90 pounds, down-stream decrease in coarse particle size was mapped for Cache la Poudre gravel, and differences among superposed gravel beds were measured for South Platte gravel.

Jan 1, 1999

By David A. Gulley

One of the advantages of the market¬place, economists believe, is that it automatically generates information which would otherwise be hard to come by. For example, supply and demand signals imply something about private and social sacrifices and benefits. This information is seldom perfect, and can neglect some costs and benefits, but it nevertheless is crucial data. Moreover, marketplaces can also eliminate the need for some information. For example; since market participants are voluntary actors, only those transactions are culminated in which a mutual gain occurs. This eliminates the need for some cost-benefit calculations. A corollary to this standard economic doctrine is that whenever a government or other party supplants a marketplace, it must generate some of the information either lost or newly-needed. (Schultze, 1977) In 1981, following a ten-year moratorium the United States government resumed leasing of publicly-owned coal. When the government designed this program, the goal was to guide the marketplace, rather than merely to respond, as a landlord, to the market's wishes. This goal has been modified somewhat, due both to the changing political climate and to the practical difficulties of implementing so ambitious an undertaking. Nevertheless, during this period of program design and implementation, part of the challenge of creating and using the necessary information fell to the professional modelling fraternity.

Jan 1, 1982

By M. Menegaki

Restoration of abandoned mine sites is still one of the weak points of mining practice. The latter stands especially for the case of the surface coal and lignite exploitations, where the extended size of the disturbed land and the drastic changes to the geomorphologic features do not facilitate the implementation of a cost effective and environmentally sound reclamation plan. The paper examines the parameters involved towards the legal requirements for the reclamation of the first lignite exploitation in Greece, namely the ?Plakes? mine, located at Euboea, due to the particularities of the site. Then an integrated redesign procedure is presented, aiming at minimizing aesthetic degradation, confronting technical difficulties and preparing the site to accept new uses.

Jan 1, 2005

By Xi Huang

The coal workers' pneumoconiosis (CWP) has been considered as the most serious health problem in the coal mining industry. The development of CWP in a worker lung depends on the average concentration and toxic components of the coal dust and the exposure length. Toxicity studies on coal dust shows the bio-available iron (BAI) in the coal dust plays an adverse role in the CWP development. It is also found that presence of calcite in the coal seams can significantly reduce the CWP cases as evidenced by the significant difference between the coal miners in the western and Appalachian coal regions. Based on this finding, it is proposed to artificially introduce calcite to BAI -containing coals in the effort to mitigate the CWP disease in coal industry. This paper introduces the scientific bases, the main geological factor that makes the differences, the proposed methods to introduce calcite to coal dust or to coal seams. Feasibility for the proposed methods is also discussed.

Jan 1, 2013

By David Sainsbury, Bevan Thompson, Yuejun Cai

The practice of placing loose rockfill as passive support in open stoping voids, of narrow vein mineral deposits, lends itself to the sterilisation of substantial mining reserves in the requirement for regional crown/sill pillars. Significant benefits are to be gained by the Australian mining industry via the development of improved guidelines for the extraction of such sterilised mine pillars. The application of selectively injecting specifically developed ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill, enables an artificial pillar to stabilise the surrounding rockmass and prevent the caving of loose rockfill from the previously backfilled void during extraction of remnant crowdsill pillars. This paper presents the results of laboratory testing used to reduce the technical risks associated with the design of cemented rockfill pillars. A laboratory testing program was devised to investigate the critical parameters influencing the performance of a stabilised rockfill matrix, along with the critical parameters influencing the interpretation of laboratory test samples. The factors investigated include; sample size and shape, particle size distribution, curing time, water quality, cement : water ratio and the confinement effect.

Jan 1, 2001

By A. Bruce Waugh, W. W. Wen, Kevin N. Clark, Neville C. Lockhart, Bruce A. Firth

Australia is the world's largest coal exporter, and technological advancement is a key element of the coal industry strategy. The issues include: increased recovery of saleable coal; enhanced quality, i.e. lower ash, moisture, fines, phosphorus (sulphur is a relatively minor problem for Australian coals); better quality control; higher throughputs/lower costs; improved handling and transport; and reduced environmental impacts. In process terms, many coal preparation operations, particularly fine coal circuits, are relatively inefficient, and all circuits must also be matched and integrated for optimum overall operation. A holistic approach to technological improvement is desirable. This paper summarises research and development efforts, within CSIRO and its collaborators, across the unit operations as outlined in the title.

Jan 1, 1995

By J. F. T. Agapito

Energy West Mining operates the Deer Creek and Cottonwood/Trail Mountain coal mines in the Wasatch Plateau about 40 km (25 miles) southwest of Price, UT. The Deer Creek Mine extracts the Upper Blind Canyon seam and the Cottonwood/Trail Mountain Mine extracts the Hiawatha seam 12 to 36 m (40 to 120 ft) below. Both seams average about 2.8 m (9 ft) in thickness. Cover depths exceed 550 m (1,800 ft) in a large portion of the unmined reserve. Stability problems at Deer Creek are mostly due to coal bursts caused by high stresses associated with deep cover and sandstone channels. Most of the bursts have occurred in gate pillars and, to a lesser extent, at the longwall face and during development. The introduction of a two-entry gateroad system with 9-m- (30-ft-) wide yield pillars has been a major factor in controlling and minimizing gate pillar [ ] bursts (Agapito et al., 1988). However, some bursting began to occur in the 9-m- (30-ft-) wide pillars as cover depths reached 550 to 610 m (1,800 to 2,000 ft). This was due to more rapid and higher abutment loading in areas with very strong roof and stiff floor.

Jan 1, 1997

By R. R. Oder, R. J. Gray

We report measurements of the effects of rank, type, and grade of coal on grinding energy and grinding media consumption in a Pitt Mill. The rank of coal has a greater effect on grinding energy than does coal type. The effect of coal grade on grinding energy depends upon the relative grindability of the mineral matter and of the hydrocarbon components of the coal. The mineral matter is primarily responsible for abrasive media wear in a Pitt Mill. The widely recognized HGI test for coal breakage may yield misleading results, particularly for multiple-banded bright and dull coal where the screening procedure used in sample preparation favors the testing of the hardest coal fraction. The work reported here indicates that the Pitt Mill, which grinds the whole coal in a single stage and which yields easily interpreted results, is an excellent candidate for testing coal pulverization characteristics including energy requirements and equipment wear. The measurements of the effects of coal characteristics on grinding energy and on media consumption have been used to estimate the cost of fine grinding in a Pitt Mill. The results, based on a conceptual level evaluation of grinding at the rate of 1 TPH, show that there are trade-offs possible between the cost of energy and cost of media consumption which involve choice of grinding media size. The use of fine-size grinding media to lower grinding energy and to increase throughput can be deceptive because the total cost of grinding must consider both energy and media consumption.

Jan 1, 1992

By James R. Dunn

The nature of water and clay in carbonate rocks is currently being investigated at Rensselaer Polytechnic Institute by various thermal and sorption techniques. Two basic concepts 'led to the present research. (1) To explain the expansion and contraction on wetting and drying of some unsound argillaceous carbonate rocks, it was postulated that the pore space around each clay particle is such that when water is sorbed by the clay, force is exerted against the pore walls. (2) The clays in expansive rocks are rejected from the growing dolomite crystals during their growth, and form a more or less connected network, thereby becoming "wettable," or available to water. New quantitative cold differential-thermal-analysis (electrocalorimetric) equipment was designed and constructed to check the "limited space" and "wettable clay" concepts and to determine the thermal nature of the transition of water to ice in rocks. This DTA equipment can detect the release of heat in freezing of less than 0.001 per cent water in a rock. Twenty-three rock cores (nine sound and fourteen unsound) and 4 procelain cylinders for standards were studied. In the nine sound rocks and in all the procelain cylinders, the rapid freezing of from 50 to 100 per cent of the water was readily detectable after 7 to 10° C of supercooling. No further freezing could be detected to -20° C. However, in eleven of the fourteen unsound rocks, no freezing was detected to as low as -40° C; in the other three, less than 50 per cent of the water froze. As a check of the DTA measurements, adsorption isotherms were determined for all materials. Calculations of theoretical freezing points for sorbed water again demonstrated that the least sound rocks had the most nonfreezable water. "Frost" sensitivity in these carbonate rocks is, therefore, probably not the result of the force of expansion of water to ice. The disruptive force is believed to result from expansion of sorbed, ordered water on clay surfaces. The relationship between the unfilled rock pores after 24-hour water saturation and the water sorbed at 85 per cent humidity at 30° C (i.e., the theoretical nonfreezable water delineates the sound and unsound carbonate rocks.

Jan 1, 1966

By M. Moss Stanley, Ronald P. Klepper

The objective of this chapter is to provide data that will assist in the selection and sizing of equipment utilized in the filtration method of separating solids from liquids. It should be recognized at the outset that in some situations more than one option may be available to achieve the target desired. In some cases purely technical objectives may be sacrificed because of cost considerations, design factors or other elements in order to satisfy optimization within the flowsheet and/or to provide bottom line results. Before considering available options, and prior to the next step of sizing out the selection, the operating criteria should be set down. The test work to develop selection and sizing data will be based on this data and the final products desired. This will help to establish initial parameters. A. GENERAL DATA 1. Material to be filtered: a. Solids b. Mother liquor 2. Feed rate of slurry in GPM 3. Density of slurry: Sp. Gr. Solids 4. Slurry: Temp. pH Viscosity 5. Source and method of feed 6. Valuable product: Solids Filtrate Both 7. Details on: Volatility Toxicity Stability 8. If flocculant is indicated, what has been used? 9. Describe product: (i.e., fibrous, cor 10. rosive, abrasive, inflammable, explosive, pasty, 11. Does product alter or require special environment during transport? 12. What type of filter media has been used successfully? 13. Is there any objection to use of a filter aid? If not, is there any preference? B. SOLIDS DATA 1. Sp. Gr. Bulk density 2. Screen analysis 3. Desired percentage moisture in cake 4. Solubility (state conditions): In mother liquor In wash water 5. Description of cake: (i.e., amorphous, fibrous, crystalline, colloidal, gran¬ular, thixotropic, 6. Special requirements for moisture de¬termination? 7. Can solids be compressed during dewatering? 8. Proposed product handling 9. Subsequent thermal drying or other pro¬cedure C. FILTRATE 1. Is separation of wash water and mother liquor desirable?

Jan 1, 1986

By Ben E. Lusk

First of all let me say what a genuine pleasure it is to be here. Acapulco certainly is a beautiful change. I'm going to spend sometime talking about change, because frankly I'm astounded at the rate of change in our world today. One good example of this, reminds me that the first time I spoke before the AIME two years ago, we were at the Ramada Inn in Beckley, West Virginia. Today we're at the Princess Hotel in Acapulco, Mexico. Now that's what I call a change. Seriously though, I'm sure you've all heard it said that the most consistent thing about our society is its constant change. Five years ago, no one could have predicted the changes we experienced in the United States during the first half of the 1970's. In the past twenty-four months alone, we have seen two presidents, three vice-presidents and hundreds of administration and government personnel changes. We have stumbled from one social crisis to another, while suffering through rising inflation, major energy shortages and labor unrest that could plunge us into a full scale economic depression. In view of these constant and unpredictable changes around us, it's obvious that we must learn to deal with change and "roll with the punches" if we are to survive. A controversial book published recently, explores in detail the various aspects of change and its impact on man.

Jan 1, 1974

By Jamal Rostami, Ataollah Rahbar, Jürgen Paulzen

"Uma Oya Multipurpose Development Project is located in South West Sri Lanka. This project, among many components, involves a 14 km headrace tunnel in very hard and abrasive igneous rocks. The tunnel is under construction by a 4.4 m diameter double shield TBM. The headrace tunnel has already reached 5km milestone and has passed through some reaches of tunnel in very strong intact rocks with no joints. Low penetration at high thrust load has caused frequent stoppages for cutter change leading to low utilization and advance rates due to low cutter life. The original machine was dressed with 27, each 432 mm (17 inch) diameter, 19 mm (3/4 inch) tipped disc cutters. However, various cutter diameters of 432-457 mm (17-18 inch) and cutter tip widths 13 to 19 mm (0.5-0.75 in), have been tried to see if cutter life and penetration rates could be increased. This paper will review the history of the project, the geology of the site, along with TBM performance and cutter life. It will focus on frequency of different cutter failures encountered in various ground conditions. Also, results of using variation of cutter diameter and tip width to cope with the hard rock conditions and their results in increasing machine productivity will be discussed. This allows for better understanding of parameters controlling disc wear/life and leads to better cutter management for more efficient operation of hard rock TBMs in similar conditions. INTRODUCTION The Uma Oya Multipurpose Development Project (UOMDP) lies in the south-eastern part of the central highland region of Sri Lanka. The Multi-Purpose Project Of Uma Oya is planned to convey water from Uma Oya to Kirindi Oya Basin for hydroelectric energy generation includes Puhulpola RCC Dam on the Uma Oya river, Dyraaba RCC Dam on the Mahatotilla Oya river, a conveyance tunnel from Uma Oya to Mahatotilla Oya (L=3750m), a long feeder tunnel from Mahatotilla Oya to Kirindi Oya river. The feeder (or power) tunnel Lot consists of a 15554 m long headrace tunnel (HRT), the surge shaft and tank on the upstream of the vertical shaft, a 650 m vertical shaft with steel lining, and an underground powerhouse and a 3650m tailrace tunnel (TRT)."

Jan 1, 2016

By K. N. Mayfield, T. Novak

"The applications for automation continue to expand within the mining industry. These applications can range from the startup, control, and shutdown of processing plants to the autonomous operation of surface haulage trucks. However, the term “automation” should not necessarily be interpreted as the total elimination of human interventions since numerous mining processes can be partially automated. The future survivability of many mining operations will be influenced by a company’s willingness and ability to understand, accept, and utilize this technology. The mining workforce, including management and engineering, should be familiar with the technological capabilities and limitations for effectively implementing automation into mines for improving safety and productivity. The Department of Mining Engineering at the University of Kentucky has recognized this educational gap and developed an automation laboratory, along with project-oriented courses at the undergraduate and graduate levels. The laboratory and the course objectives are described in this paper, as well as the skills and abilities that students obtain at the completion of the course(s). BACKGROUND The touted benefits of automation include: improved productivity, lower operating costs, reduced drudgery of repetitive operations performed by workers, and the removal of workers from hazardous locations. The acceptance of advanced technology by the mining industry, however, has traditionally been slow. This cautious approach is understandable considering the complex and harsh conditions routinely encountered in mining operations. Bad experiences with some premature installations of newly hyped technologies may have also resulted in lingering skepticism by many mine operators. Nonetheless, with thoroughly demonstrated reliability and proven applications, automation based on programmable logic controllers (PLCs) has made significant inroads into the mining industry. Programmable logic controllers (PLCs) are the workhorses of automation. They were originally conceived in the late 1960s, long before the invention of the personal computer (PC). Initial PLC applications were directed towards sequential relay control in manufacturing plants, which subsequently eliminated the use of “relay logic” that was based on hard-wired electromechanical relays. With continuous advancements in electronics and computer technology over the years, PLCs have evolved into sophisticated and powerful devices with very stable operating systems. They are designed for deterministic logic execution with extreme consistency in timing, along with a high tolerance to temperature, humidity, and vibration (Smith 2003). Because of their robust characteristics, PLC networks now provide the backbone for most industrial automation applications."

Jan 1, 2017

By E. A. Metz

Silicon dioxide, silica, is the most common oxide in the earth' s crust. The health effects of silicon dioxide dust have been known since Biblical times. Agricola's book, published in the mid 1500's on occupational medicine, described a lung disease that afflicted miners. He observed a disease in miners that caused shortness of breath, coughing and wasting. Add fever, chest pains and fatigue and we have the current symptom complex of silicosis. As we approached the 21stcentury, the Labor Department began an aggressive campaign to combat silicosis-a preventable disease. Unfortunately, many publications do not clearly differentiate the polymorphs of silica known to mineralogists. Crystalline silica, i.e., alpha quartz, tridymite and cristobalite need to be considered differently from the amorphous forms of silica. Freshly fractured surfaces of the silica and host specific responses will be examined. Recent research focuses on the biologic interactions of free radicals generated by mineral particles. This results in cell injury and DNA damage, in turn leading to fibrogenesis and possibly carcinogenesis. In addition to particle-cell interactions, emphasis is given to lung defense mechanisms.

Jan 1, 1998

By Allegra Yeley, Ted Klemetti, Gamal Rashed, Tim Miller, Nicole Evanek

In 2015, the Subtropolis Mine in Petersburg, OH, experienced a massive ground collapse that continues to grow over time. Horizontal stress effects have affected the roof at this operation in the past and may have played a large role in this collapse. Horizontal stress can impact the roof and floor stability and endanger the health and safety of underground stone miners. Mines experiencing damaging effects from horizontal stress typically find that the principal stress direction is the same throughout the mine and the region. At the Subtropolis Mine the principal horizontal stress direction appears to change as conditions change and differs from the regional horizontal stress, particularly near the collapse or other roof fall areas. The growth over time of this collapse and other roof falls have been captured and analyzed using geologic mapping, 3D LiDAR scanning, numerical modeling and geographic information systems like ArcGIS. Utilizing these tools to better understand sitespecific conditions can be critical to reducing the potential of massive ground collapses in the underground limestone industry.

Feb 1, 2024