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By Frederick B. Brien

For many years tin mining in Bolivia has been very important to the economy of the country. In recent years the tin content of the ore reserves has been steadily declining. An improvement in concentration efficiency is highly desirable in order to increase productivity from the present-low-grade mine ores and to allow retreatment of the many millions of tons of tailings from past operations, some of which equal the present ores in tin content. A number of investigators have been or at present are working on various phases or approaches to the problem. Gravity concentration is used in Bolivia today as it has been in the past to recover tin minerals from the mine ores. An objective of the work reported in this paper was to examine the possibility of treating present low-grade ores and sink-float tailings products, at a relatively coarse grind, in order to produce a higher grade feed material to the present gravity concentration plants. The possibility of using heavy liquids in cyclones to treat large tonnages with a minimum of outlay presented itself and is of particular interest since appropriate heavy liquids are available and with physical properties which lend themselves to simple recovery methods. Tests were carried out using a closed circuit laboratory cyclone assembly. It was desirable to determine the value of using the SG50 concept and Tromp curves for analyzing the cyclone concentration test results. The effects of entrained water on the behavior of ore particles in the cyclone were examined.

Jan 1, 1964

By Ben Sosewitz

The subject of rapid excavation tunneling is one that is extremely important to the people in the Metropolitan area of Chicago. My personal observation is that it is also extremely important to the urban communities around the U.S., to many local and state governments, and to the public officials who are deeply concerned about state affairs and taxes. The Metropolitan Chicago area is in fact, (as are 40 other major urban areas in the U.S.) confronted at the present time with a very serious combined sewer overflow, drainage and pollution problem which accounts for an estimated 40% of the pollutional load on its waterway system. In response to this the District has to date spent some seven millions of dollars in an attempt to find the most economical solution available for the elimination of this problem. This study included extensive investigations of the geological strata, the quantity and quality of storm runoff to be dealt with, and the various methods of storage and treatment available. It has considered solving the overflow problem by a concept involving a series of tunnels, rock tunnels, shafts and storage areas which will collect, retain and subsequently treat that portion of the combined sewer overflow which can be handled in the most cost-effective and economical way, consistent with following the federal and state standards - with which we at the present time agree in principle.

Jan 1, 1997

By David Caiden, Geoffrey Fosbrook, Jaidev Sankar, Donald Phillips, Jon Hurt, Anil Parikh

This paper will cover the progress being made on Phase 1 of New York’s Second Avenue Subway line. It will include a description of construction progress on the first contract to be let, which consists of a 248 m (815 ft) long launch box, 3.9 km(2.4 miles) of TBM tunnels and a tunnel sump; the packaging strategy for the remaining work; and the progress through Final Design of the remaining packages, including the two large span rock cavern stations.

Jan 1, 2007

By J. Walden, S. Rhoades, R. E. Miller, R. Gibbs, P. Boman

Accelerometers and pressure transducers mounted in suspension components can be used to monitor the ride of haulage trucks. Presently, it is difficult to tell what caused a jolt to the truck using either pressure or acceleration data alone. When information from a Global Positioning System is recorded at the same time as shock pressures or acceleration data, then the exact location of an event can be determined. Mine management can then determine what caused the jolt to the truck.

Jan 1, 1999

By J. Hines

Traditionally, fuel oil or diesel was the collector of choice in coal flotation, but in recent years these materials have come under increased scrutiny because of concerns about the toxicity of some components. In response to these concerns, Georgia-Pacific Chemicals LLC has commercialized a patent pending coal collector (Talon® 9400 reagent) that is 100% derived from the pulping of trees. This study presents a comparison of yields and recoveries for different coal collectors, including the one derived from the pulping of trees.

Jan 1, 2011

By Bradshaw, Y. S. Cho

The size of bubbles plays an important role in flotation. Equations used to calculate the size of bubbles all show the effect of liquid/gas surface tension. However, the surface tension does not change much with frother concentration and experiments conducted using single capillaries (or single-hole spargers) do not reveal any clear effect of the frother concentration on bubble size. The size of bubbles does, however, strongly depend on frother concentration when multi-hole spargers are utilized (or when measured in a flotation cell); at low frother concentrations the bubble size is much larger indicating coalescence as a main mechanism determining the size. Coalescence can be prevented at frother concentrations exceeding the critical coalescence concentration (CCC), which in turn was found to be interrelated with the dynamic foamibility index (DFI).

Jan 1, 2001

By J. D. Miller

Characterization of feed material with respect to expected concentrate grade and recovery is fundamental to the design of improved separation efficiencies and to achieve sustainable development in the utilization of our mineral resources. An important reference point for this characterization is the liberation-limited grade/recovery curve which represents the perfect separation, the best separation which can be achieved for a given feed material limited only by the extent of liberation. Now, liberation-limited grade/recovery curves can be determined based on 3D mineral liberation analysis of feed material. Thus, actual separation efficiencies can be compared to what might be expected for a perfect separation limited only by the extent of liberation. It is shown that 3D mineral liberation analysis based on X-ray micro CT (XMCT) is preferred to 2D section analysis which overestimates the extent of liberation. By way of example, procedures and experimental results are presented and discussed for feed material in the case of phosphate rock flotation.

Jan 1, 2009

By Gordon Cook

American Electric Power Company (AEP operates 31 coal mines in three states, and some 26 electric generating stations (19 coal-fired) located in the Ohio River Basin. Normally the system burns over 36,071,600 tonnes (40,000,000 tons) of coal and generates in excess of 3.6 X 1018 J (100 billion kwh) of electricity per year. In 1975, AEP, in response to the progressively more stringent air quality requirements of the clean air act, acquired large low-sulfur reserves in Carbon County, Utah (Figure 1. Location Map). Price River Coal Company (PRCC) is the operator OF this multi-seam complex, which is part of the Book Cliffs coalfield at an elevation exceeding 1,829 m (6,000 ft.). The topography is mountainous and divided by numerous canyons. Flat areas are at a premium (Figure 2. Castle Gate Area). Modern high production longwall mining takes in some top and bottom waste, and in this particular operation, it amounts to about 14% of the ROM tonnage.

Jan 1, 1983

By J. Geisler

When addressing Germany’s resource supplies, we need to distinguish between those domestically available and imported ones. Resource extraction ostensibly competes with the designation of protection areas. However, the parallel existence of wildlife and plant life, and operations in the areas used for resource extractions is continually underestimated. The European Commission has compiled guidance documents facilitating the extraction of resources from protected areas. With regard to resource productivity, the market appears to be the appropriate instrument for minimising resource consumption. Policy makers are now called upon to create a legal framework leading to a consensus accepted by society.

Jan 1, 2011

By Mark E. Smith

Oxide ores can consume enormous amounts of expensive sulfuric acid. The problem is amplified with increasing heap heights. One solution is to provide a thin liner and drainage system between each lift of ore, thereby intercepting the pregnant leach leach solution (PLS) after it exits the active lift. However, these liner systems require special attention to hydraulics, slope stability and geomembrane design criteria. Inadequate attention to the first two can result in reduced recoveries, increased acid consumption andsystem failures. The geomembrane selection criteria are different from the base liner, and optimizing its selection can have significant effects on the operation’s bottom line.

Jan 1, 1996

By W. J. Miles

Many years ago, a relationship was established between dust inhalation and pneumoconiosis. Since then, various government agencies have regulated crystalline and amorphous forms of silica material in the workplace. In 1987, the International Agency for Research on Cancer (IARC) classified crystalline silica as a probable carcinogen. With this listing, crystalline silica became a regulated substance under the Hazard Communication Standard. The minerals and chemicals industries have responded in various ways. They have: • developed worker and user training programs and literature; • labeled products with appropriate warnings; • continued to implement dust reduction programs; and • developed meaningful epidemiological studies of workers. • begun development of reliable analytical methods for measuring crystalline silica at the 0.1 % threshold level; Background Silicosis historically has been the major health hazard resulting from exposure to crystalline silica. Silicosis is the scarring of the lung from excessive exposure to crystalline silica. It has been recognized as an occupational disease for more than 2000 years, since early Greek physicians noted the respiratory problems of miners, stonecutters, and quarrymen who were exposed to excessive quantities of mineral dust. During the industrial revolution, the incidence of the disease was greatly increased by the use of machinery that increased dust levels. Subsequently, the need for dust control was recognized and measures were instituted. Silicosis is characterized by progressive breathlessness on exertion and develops over the course of years. Xray images of the lungs show

Jan 1, 1990

By H. Hejny

"The mine of the future will exploit mineral raw materials at greater depths than today, requiring completely different approaches compared to today’s deep mines, in order to get mineral rights. Only these eco-efficient mines will contribute to improved access to domestic mineral resources, secure the sustainable supply of mineral raw materials for Europe and reduce the import dependency. IntelliMine will contribute to realise these concepts of invisible, zero-impact and safe mines. The mine of tomorrow will run an integrated concept in order to guarantee the desired level of sustainability. All operations necessary for the eco-efficient provision of the minerals including waste management will be carried out underground. This will drastically reduce the volumes being transported, minimising above ground installations and thus the environmental impact. IntelliMine will develop necessary innovative methods, technologies, machines and equipment for the safe, eco-innovative, intelligent and economic exploitation of mineral raw materials in the EU, especially at greater depths."

Jan 1, 2011

By M. H. Pelkki, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Research has shown that excessive soil compaction is detrimental to the establishment of trees in reclaimed soils. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed soils. It is believed that reclamation practices which minimize soil compaction will produce better results when forestland is the intended post-mining use. The University of Kentucky has developed reforestation test cells on reclaimed soils at a surface mine in eastern Kentucky to test this hypothesis. Each test cell has been planted with various species of trees, and since 1997, data have been collected at these test cells for soil average dry bulk density, average penetration resistance, average depth to refusal, and average survival rate of trees. These data have been correlated to determine the relationship between soil compaction and tree survival rate. It is believed that the two soil compaction parameters may ultimately be used to predict tree survival rates on reclaimed surface mined lands.

Jan 1, 2001

How did you get into mining; were you from a mining town or mining family? Not at all. I grew up in northwest Kansas. I liked to hunt and fish, so I thought it would be fun to work for a company that made knives or guns. It seemed like metallurgical engineers would be something those companies could use, so I started in physical metallurgy. I got a summer job at the great Climax molybdenum mine near Leadville, CO shoveling muck onto conveyors. I was hooked. I loved everything about mining, so in the fall, I changed majors from physical metallurgy to mineral processing. For many years you actually discouraged young people from studying the mining disciplines. Could that be right? That’s true.

Jan 1, 2007

By Roozbeh Afzali

Designing an appropriate tunnel blasting pattern reduces the cost of rock breakage and subsequent operations such as loading, haulage and support of tunnels. For that reason, we developed a software that designs tunnel blasting patterns. Using this software, three different tunnel blast design models based on parallel hole cut, namely, Swedish, Konya and Energy Balance, were investigated and compared for a virtual tunnel. Accordingly, blasting patterns were designed, for different cross sections. The trend of parameters such as specific charge and specific drilling as functions of tunnel cross-section was determined for each model. Our results show that, in general, The Swedish model gives lower specific charge and specific drilling compared to other models.

Jan 1, 2008

By Jacques Nantel

Mechanization has been at the core of productivity improvements since the industrial revolution. During the past 20 years, mining has derived spectacular progress from mechanization. In the future, however, mechanization alone will not be enough. In the next few decades, automation will bring about new generations of highly productive and safe machines, with low operating costs. Increased use of new and better technology is generally accepted as the prime factor capable of closing the productivity gap. The productivity gap is the difference between inflation and metal prices. The three S-curves in Fig. I represent the evolution of technology in general, and mining in particular. TI represents incremental changes. the dominant sort of technology changes in the mining industry: - Better drills, electric hydraulic drills vs. pneumatic drills, the drilling rate is twice as fast. - Better steel and bits, to accommodate the higher performance drills. - Improved chemical explosives. - Bigger trucks in open pits.

Jan 1, 1993

By G. Caron, M. Boisclair

In 2005, CANMET-MMSL used its pool of expertise in ground control, open pit and underground mine engineering, mineral processing, information technology and applied mineralogy to launch a mine-to-mill research project. The objective of the project was to optimize the distribution of rock breakage energy among blasting, crushing and grinding activities, thereby maximizing the efficiency of energy utilization within comminution processes. Tests were designed to demonstrate that this approach could reduce the energy consumption, thus contributing to the reduction of Green House Gas (GHG) production in the Canadian mining industry. The project was accomplished in collaboration with DynoConsult and Dyno Nobel Canada Inc., a world leader in commercial explosives. Data analysis from 12 blasts (six with electronic and six with pyrotechnic detonators) in three different geological formations of a quarry (soft, medium and hard rock) shows that electronic blasting technology increases rock fragmentation by 15% (in hard rock) to 20% (in soft rock). A more uniform rock fragment size distribution is also obtained. The impact of the improved quality blast product on downstream processes of the quarry is a productivity increase of 5% in rock excavation and transportation, an energy reduction of 10% at the primary crusher and an increase of 15% of the primary crusher throughput. A soft-sensor prototype, based on primary crusher data (i.e. energy consumption, throughput, feed and product size distribution) and a simplified computerized process model, was developed for on-line measurement of the rock operating work index. Additionally, 385 rock samples and specimens were collected and prepared to determine the tensile and compressive strength of the rock material, to evaluate the aggregate crushing work index, and to examine the development of micro- and macro-fractures by means of binocular and SEM microscopy. Blast-induced rock damage was evaluated at the end of the laboratory testing program. Even though a reduction of rock hardness of around 30% was observed after blasting, the impact of the blasting method (i.e. use of electronic or pyrotechnic detonators) on the induced rock damage could not be observed. It is either absent or not perceptible with the accuracy of the measuring techniques and the number of samples analyzed.

Jan 1, 2007

By Raymond P. Miller, David L. Monson, Robert A. Robinson

A geotechnical instrumentation program consisting of borehole extensometers and portable tape extensometer stations was effectively used to monitor concrete liner deformations and guide construction procedures during enlargement of a 75-year old Union Pacific Railroad tunnel in Wyoming. Enlargement involved excavation of the old concrete invert and placement of 5,941 feet of new concrete invert 6 feet lower in squeezing shales, fault zones and water-bearing sandstones. Instrumentation data were used to guide procedures for excavating the old invert, installation of temporary interior struts, underpinning existing liner walls, and placing the new concrete invert.

Jan 1, 1976

By David L. Shearer

INTRODUCTON James Howden first secured an order for two Service Tunnel Boring machines in November 1986. These Tunnel Boring machines were 5.7 and 5.4 metres in diameter and the full length including back up was 215 metres. Manufacture commenced in December 1986 at the Glasgow factories of James Howden & Company with the deliveries to site of the machines in September 1987 and March 1988 respectively. In December 1987 two further orders were secured for the land running tunnels at 8.7 metres diameter. This paper presents some of the challenges in building tunnel boring machines for the Eurotunnel project between Britain and France. The general specifications of the Tunnel Boring machines and length of drives are shown in Appendix 1. DESIGN PARAMETERS The specification given by the Consortium TML on behalf of their client Eurotunnel cleary indicated that cutting of the face should be concurrent with the building of the precast concrete lining rings. In order to do this a telescopic machine was thought to be the best solution. Ground conditions were described as chalk marls of homogeneous nature with the possibility of friable areas and some revelling. A shielded type TBM with open cutter head was chosen together with a telescopic section and a rear

Jan 1, 1989

By M. Karmis, S. K. Weisiger

The traditional method for training personnel in the mining and other heavy industries has been face-to-face, either via a lecturer in a classroom or through an apprenticeship. With the advent of applications tools such as video, computers, and the Internet, however, a much broader range of training delivery methods is available. Especially exciting are the broad capabilities of multimedia packages that combine the best features of numerous delivery methods. Applying multimedia environments in training holds great potential, especially when there is considerable difficulty in reconstructing real training environments. The authors discuss various delivery methods currently used in training employees, including perceived advantages and disadvantages of those methods. The authors then discuss and evaluate current computer-based training efforts of the mining industry and present an example of a multimedia training tool.

Jan 1, 2001