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By Alvin Kaufman

Malthus, an eighteenth century economist, predicted a rather dismal future for the world. It was his contention food supplies would not be sufficient for the population of the world because the economy of a nation grew arithmetically while population increased geometrically. As a consequence, within a relatively few years mass famine would spread throughout the world. This prophecy, based on an agrarian economic situation, did not come true at least insofar as the Western World was concerned. In largo measure, the salvation of our part of the earth resulted from the growth engendered by the Industrial Revolution. Throughout much of today's world, however, the Malthusian theory seems to be coming true. The advantages and benefits of the Industrial Revolution have net reached all nations. Further, the situation has been compounded by the benefits of modern medicine. This has reduced child mortality and extended life expectancy, but placed no limitations on births in the developed countries, child mortality has declined to 2 percent and adult life expectancy has doubled, but education and general prosperity have resulted in voluntary limitations on pregnancies thus partly offsetting the increased chance of survivals Even so, the present rate of population increase in Europe is approximately 6 percent per decade, and somewhat higher in the U.S., Japan, and other developed countries. The world as a whole, however, is expected to double its population by the year 2000, This would imply a rate of increase in the less developed countries approximately four times that in Europe.

Jan 1, 1966

By Joseph K. Cavey

To accommodate the new Pier A expansion at BWI airport, a 1.8 m (6.0 ft)diameter stormwater pipe was constructed below active Runway 15R-33L. The jacked tunnel alignment runs east/west below the runway, and the depth the crown was 6.1 m(20 ft). Soil conditions consisted of very loose to medium sand and gravel, with some medium stiff clay and silt. Super Jet Grouting was selected as the ground treatment system, creating large diameter columns. All work was performed from the surface of the runway between the hours of 12 am and 6 am. Monitoring points along the tunnel in the grout zone indicated zero settlement during tunneling. Tunneling operations in front of and beyond the treatment zone experienced significant settlement. Super Jet Grouting in the treatment zone provided a low permeability continuous stable soilcrete that was readily mined while the runway remained in service.

Jan 1, 2003

By T. O. Kuhl

The Royal-Mountain King Project is 7.2 kilometers (4.5 miles) northwest of Copperopolis, California. Reserves of 8,250,000 t (9,100,000 st) at 2.32 g/t (0.068 oz/st) gold will be processed at 2500 t/d (2750 st/d) from three pits. Production is scheduled to begin the first quarter of 1989. District geology consists of northwest trending sequences of Jurassic meta-sedimentary and meta-volcanic rocks. Three ore bodies are located along the Hodson fault which trends northwest and dips 40 degrees northeast. The Gold Knoll and North Pit ore bodies are hosted in carbonate and silica altered meta-volcanic rocks whereas the Skyrocket ore body is hosted in quartz stockwork zones in meta-sedimentary rocks. Gold is present as inclusions and micro-veinlets in pyrite.

Jan 1, 1989

By Drummond Earley III

The hydrology of in situ leach mining operations is being studied by the U.S. Bureau of Mines using a variety of techniques, and the Bureau has made significant advances in tracking and modeling the flow of leach solutions in rock formations. However, the influence that leach solution composition has on the hydrology of these systems is poorly understood, and geochemically-controlled changes in the hydrologic characteristic of ore deposits during in situ leach mining of porphyry-hosted, copper oxide ores have not been previously studied. The Cyprus Casa Grande in situ leach mining operation mines fracture-hosted and disseminated copper oxides (predominantly chrysocolla) hosted by granodiorite porphyry using a pattern of underground wells. The injection solution consists of sulfuric acid raffinate from a solvent extraction-electrowinning plant. Chemical analysis of representative injection and recovery solutions reveals that gangue cation concentrations in these solutions are high, and geochemical modeling shows that the solutions are saturated or nearly saturated with respect to gypsum, jarosite, and various amorphous oxides. Precipitation of these solids is evoked by calcium-exchange reactions, rising pH, and perhaps locally rising redox potential, as the leach solution reacts with the ore minerals, host rocks, and the atmosphere. Mass and volume balance calculations show that approximately 25 cm of precipitates are formed per gram of copper recovered at Cyprus Casa Grande. The results of geochemical modeling agree with petrologic examination of pre-and post-leach core samples from the leached horizon. Moreover, hydrochemical modeling and hydrologic field data suggests that chemical precipitation causes significant decreases in porosity and permeability during in situ leach mining of porphyry-hosted, copper oxide ore.

Jan 1, 1992

By Steven J. Schatzel, Kayode M. Ajayi, Zoheir Khademian

The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine creating safety concerns. To provide recommendations for developing guidelines that ensure a safe co-existence of longwall mining and unconventional shale gas production, this study evaluates the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach using a discrete fracture network (DFN) model. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations is within values validated with field measurements. The results show that a decrease in fracture aperture (potentially due to longwall-induced stress in the likely vicinity of the breach location) reduces the potential gas flow to the mine by a significantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas flow to the mine by over 70%. Similarly, changes in the fracture water saturation level significantly affect the gas flow. In all cases, the potential gas flow to the mine is higher if the casing breach occurs at an increased gas well pressure. These findings provide critical information regarding the impact of each of the parameters associated with gas flow in the event of a shale gas casing breach near a longwall mine and could help towards the development of guidelines to ensure a safe coexistence of both industries.

Sep 28, 2022

By S. K. Singh

"Feather edging"-a major source of injury and fatal accidents in Australia, South Africa and USA, refers to a phenomenon where the roof, at the goaf edge, falls as a thin wafer of rock often suddenly, over-riding conventional timber breakerlines. It may run down and affect adversely a working bord at distances of 15 metres or more from the goaf edge. Feather edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a mine trial where a concentrated row of fully grouted bolts were able to resist the feather edging in the first comprehensive, monitored trial in an Australian pillar ('total') extraction coal mine.

Jan 1, 1999

By O. Salami, G. Xu

Fire accident is one of the most classic safety concerns in underground mines both in the USA and abroad. It may occur from pool fires due to leakages in hose or pipes, vehicle fires, or fires in tires and conveyor belts in the underground mines. It may also result from the storage of flammable materials such as gasoline, diesel, and explosives in the underground. When fire occurs in an underground mine, it releases heat, smoke, and other toxic gases such as carbon monoxide, and methane to the surrounding thereby making life unbearable to the miners. Furthermore, smoke greatly impact visibility in the underground which makes evacuation even more onerous and challenging. To this end, a thorough investigation of fire behavior and spread of toxic gases in a practical underground mine is imperative to develop a reliable emergency evacuation plan in an event of fire disaster in the underground mine. The objective of this study is to investigate temperature variation and CO spread along mine airways by conducting full-scale fire experiment in the underground mine. The results presented from this study are crucial to developing evacuation plans in underground mines. In addition, the findings from this study could be used to validate existing evacuation models.

Mar 2, 2022

By H. Sis

The pressure filtration behavior of dispersed and flocculated alumina slurries at high percent loadings is discussed with an objective to determine the effect of surfactant type and concentration on slurry properties. A high purity alumina powder was used as a model solid. Dispersion of the alumina was controlled by surfactants that are considered to act by electric and steric stabilizers. The effect of both the ionic and nonionic surfactants was investigated. Surface charge measurements of the slurries were carried out by electrokinetic sonic amplitude (ESA) method to understand the mechanisms. The effect of surfactant type and concentration on the kinetics of pressure filtration and final cake properties are discussed.

Jan 1, 1998

By G. Ferrara

During several years of operation in Europe, South Africa and other countries, the Tri-Flo has demonstrated to represent a substantial improvement of the dense medium dynamic separation systems. The reasons are: (1) high sharpness separation due to the multistage system and the application of new concepts in designing the regeneration circuit and controlling the medium rheology; (2) the possibility of performing two cuts at different densities using a since separation device and a single regeneration circuit. The paper discusses in detail the above mentioned points, with particular reference to the multistage technology, based on the circuit analysis theory, and to the control of the medium rheology based on recent work in the modelling, and simulation of the rheological behavior of dense suspensions.

Jan 1, 1993

By David A. Zegeer

It's a pleasure to be here, and an honor to be invited to address this distinguished group of professionals. Today, I'd like to begin with an overview of progress in coal mine safety and health. I'll discuss some current areas of concern. And I'll make some suggestions as to where we may be headed in the future. This year marks the coal industry's 15th anniversary under the Coal Mine Safety and Health Act, which took effect in 1970. We have come a long way in those 15 years. As a coal mining man from way back, I remember the era when the Coal Mine Safety and Health Act first was passed. Some of you may remember it, too. At that time, the safety and health of coal miners was in the public eye even more than it is at present. One reason was a mine explosion that killed 78 miners when it occurred in a large underground coal mine in November 1968. That disaster raised tremendous public concern about protecting the safety of miners.

Jan 1, 1985

By William F. Lawrence

Due to the immense volumes of municipal wastes that are generated in this nation every year, it has become imperative that effective measures be developed to utilize all or portions of these materials in a productive and efficient manner. Nany larger municipalities employ incineration to reduce the bulk of material to be removed to disposal sites: but, even after incineration, approximately one-fourth of the original waste material in the form of non-combustible residue and flyash remain. It has been found that the flyash fraction of the incinerator residue contains varying amounts of copper, silver, gold, aluminum, iron and titanium along with many other important metals. The serious loss of these natural resources contained within the flyash and the monetary expense of current disposal methods present a serious and rapidly increasing problem to the public and to the Federal Government. The growing emphasis upon environmental control, rapidly increasing urban population and "convenience packaging" 'with its attendant increased waste production has led to the initiation of a broad range of studies concerning municipal waste. For example, the U. S. Bureau of I-lines is investigating all aspects of the incineration of municipal waste under its solid waste disposal program.l "In-house" studies range from improved incinerator design to potential recovery and recycling of the various components within the incinerator residue. A major portion of the latter research is being performed at the U. S. Bureau of ;-lines, College Park, Maryland facility while grants for specific areas of study have been issued to several universities and research institutes. In addition, the Department of Health, Education and Welfare has supported programs examining the potential recovery of paper; glass, metals and other components of unincinerated refuse followed by disposal in sanitary landfills.

Jan 1, 1971

By G. Paul Anderson

Personnel at Utah Copper Division's Bingham Canyon Mine use current computing technology to compile pertinent production statistics and mining plans. Within hours after the day's work has been completed, concise reports summarizing the previous day's production statistics, actual production vs. budget statistics, the location of shovels relevant to the mining plan, the performance of equipment, equipment next scheduled for maintenance, etc. are available at the terminals located throughout the mine. Also, engineering personnel us e computerized systems, directly from their offices, to assist them in the timely development of mining plans. Timely and concise reporting and planning capabilities such as these assist mine personnel in their efforts to review mining progress and equipment performance, and as such they are in a better position to detect adverse trends early and to seek appropriate resources or make changes in plans or practices.

Jan 1, 1977

By R. L. Amelunxen

P. T. Freeport Indonesia (PI) in conjunction with Crescent Technology Inc. has developed a method to predict the metallurgical performance of ores blends based on the behavior of their component ores. The question addressed in this paper is whether ores treated individually could be extrapolated to predict the behavior of a blend of ores. The work further investigates the use of modal analysis to establish individual mineral flotation kinetics in each of the ore zones. This information would lead to the prediction of grade-recovery curves of ores made up of those minerals. Nine samples of ore, representing various zones of FI's Grasberg ore deposit were tested metallurgically and examined microscopically. The same testwork was performed on blends depicting the 1994 mill quarterly feed. Flotation kinetics of the individual ores were then "mathematically" blended and compared to the results obtained from the quarterlies. The calculated kinetics of the actual blends of ore received by the mill were fed to the simulation program and compared to the actual mill performance.

Jan 1, 1995

By D. C. Lynch

While silica ores are generally considered to have little value, those with exceptionally low B and P content have, potentially, significant worth if processed for use in photovoltaics. The sales value of a cubic meter of ?run of the mill? silica sand is $42 per cubic meter (retail and delivered). If the silica sand can be used to produce solar silicon, its value after processing is $34,000 per cubic meter. Factors that impact the suitability of silica for direct processing in production of photovoltaics are examined.

Jan 1, 2010

By D. Lelinski

Air-sparged hydrocyclone (ASH) flotation is one of the new promising technologies. Numerous applications have been successfully tested since its conception; nevertheless, research and development efforts have continued to provide for further improvements with respect to operating conditions and design considerations. Results from experimental studies on bubbles generation in the ASH system are presented in this paper. Bubble size distributions generated during ASH operation have been determined using a high-speed photographic technique. The influence of many factors including surfactant concentration, water flowrate, and porous tube pore size has been studied. Test results indicate that these process variables have a profound effect on the bubble size distribution. With an increase in surfactant concentration or water flowrate (shear field) the bubble size distributions become narrower and shift toward smaller average bubble diameters. However, the influence of pore size is more complicated. Depending on the experimental conditions the average bubble size was found to range from about 100 to 300 microns in diameter.

Jan 1, 1995

By Lawrence K. Nordell, Vinit Sethi

Published standards and specifications do not adequately cover engineered class pulleys for modern high strength steel cord belt conveyors. This paper discusses the Conveyor Dynamics, Inc. (CDI) design criteria and stress analysis techniques emphasizing the finite element method (FEM), fatigue failure criteria, design limits and manufacturing requirements to ensure successful and safe pulley installations.

Jan 1, 1993

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024

By J. Y. Kim

Lead ions originating from galena during processing of complex sulphide ores migrate to "cover" the surface of sphalerite and iron sulphide mineral particles, and cause poor selectivity in differential flotation. Generally in sulphide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. Subsequently, surface lead complicates the zinc flotation circuit by lowering the concentrate grade due to the co-flotation of lead-activated iron sulphide minerals. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zn and Pb-Zn ores is discussed. Plant and laboratory test data are interpreted by determining the surface composition of individual grains of sphalerite and iron sulphide particles using two surface analytical techniques, Laser Ionization Mass Spectrometer (LIMS) and Time of Flight-Secondary Ion Mass Spectrometer (TOF-SIMS). Cationic and anionic species on the surface were analyzed to elucidate the phenomena.

Jan 1, 1995

By Russell Clough

The Pacheco Pumping Plant is situated on the west end of San Luis Reservoir in western Merced County, California. It is designed to draw water from the reservoir and pump it into a 3,500,000 gallon regulating tank. The water then flows entirely by gravity to the Coyote Pump Station in Morgan Hill, a distance of 40 miles, where it is pumped into Anderson Reservoir. This water is used to recharge the depleted groundwater table in the Santa Clara Valley. Eventually, some of the water will be diverted to Hollister in San Benito County and to Watsonville and Santa Cruz in Santa Cruz County. The owner is the United States Bureau of Reclamation. The underground work consisted of a fifteen foot finished diameter surge shaft 250 feet deep to the crown of the pump chamber; a twenty foot finished diameter pump chamber which declined from the shaft at 14.2% for ninety feet and then ran horizontally for 180 feet; and twelve each five foot diameter steel lined intake shafts 240 feet deep which intersect the pump chamber in the horizontal section. (Figure 1) Upon completion of the pump chamber, the contractor had to dewater the existing tunnel under the reservoir, excavate the remaining fifteen foot plug, and concrete the transition. The low bidder for this contract was Underground - Continental-Heller at 414,456,000. Excavation of the open cut for the pumping plant and surge shaft began on April 14, 1983. This was performed using a Koehring 1066D backhoe, dozer, trucks, and two Cat 631 scrapers. The excavation was started at the surge shaft so that the grouting could begin

Jan 1, 1985

By Thomas A. Simpson

Traveling through the moors and valleys of Cornwall, England, one is reminded of the extensive mining activities of the past. Abandoned shafts, remains of granite block wheel houses and engine houses, battered brick stacks, old calciners, overgrown water wheel pits, count house remains, overgrown waste pits, and old portals are gaunt monuments to a once flourishing mining industry. Cornwall is bordered on the north by Devon and occupies the south-western most tip of Great Britain. The Atlantic Ocean borders the promontory; to the north, the mouth of the famous Bristol Channel faces the open sea; and to the south, the English Channel separates the land masses of Great Britain and Europe. This part of England is probably the most extensively mined ground in all of Europe. Such great mines as Dolcoath and Wheel Vor, Consols and South Carodan, Levant and Bottalack, remain legendary in the annals of metal mining in the nineteenth century. Many US mining districts hold close ties with Cornwall, Devon, and Wales through ancestors who emigrated from there to work in US mines in the eighteenth and early nineteenth centuries. Their descendants can be found in many major US mining districts, and their terms, expressions, customs, and methods have left an impact on the US mining scene that remains with us today.

Jan 9, 1981