Search Documents

By F. B. Olender

Idler engineering, operation, and maintenance cannot be covered in depth in a short paper. Therefore, this will be a general look into the subject matter in light or the present-day technology. Depending on the source or reference used, belts for handling bulk material underground came into being between 1900 and 1920, while strip mining appeared in the thirties. The conveyor belt speeds in that era were in the 300 rpm to 500 rpm range. Belt speeds or 600-700 rpm were in vogue in the thirties, and the early sixties saw speeds or 800-900 rpm. Today, speeds or 1000 rpm are not looked at with dismay; in fact, speeds or 2000 rpm are being discussed. Among the driving forces moving the bulk materials handling industry to these greater heights have been the mining operators and engineers. Their appetite to increase output, yield, and reduced per-ton costs has constantly challenged the bulk material handling industry to develop products capable or handling these increased capacities. One or the products affected by this movement is the idler. Apart from the conveyor belt itself, it is one or the most significant parts or a conveyor system because or the sheer numbers needed in an installation.

Jan 1, 1971

By G. Davis

It is well known that the anticipated mineral price at the start of a prospective mineral project can have an overwhelming effect on a property's ex ante value. However, possible price movements throughout the life of a project can also have an impact on this value. This paper demonstrates how different potential price paths can affect project value. When considering commodity price projections for mine valuations, it is thus necessary to estimate not only the expected commodity price at the start of the project, but also the manner in which that price is likely to fluctuate throughout the project's life.

Jan 1, 1995

By P. Geoffrey Feiss

The Piedmont province of the southern Appalachians is becoming the focus of interest for many exploration geologists. In the past, only those deposits with significant surface exposure have been exploited. Thus, few deposits have been found and relatively little exploration has been conducted in recent years. Modern geochemical and geophysical techniques can alleviate this problem of concentrating on exposed ore bodies by allowing us to "look through" the soil and saprolite to detect the presence of significant mineralization at depth. This paper will attempt to evaluate the feasibility and effectiveness of several geo¬chemical exploration techniques in the Piedmont, of Cabarrus and Stanly Counties, North Carolina. The area chosen for the study is shown in Figure 1, lying almost wholly within the Mt. Pleasant quadrangle, North Carolina. The area is on the eastern boundary between the Charlotte belt, a zone of plutonic and intermediate grade metamorphic rocks, and the Carolina Slate belt, a series of complexly interbedded volcanic and sedimentary rocks of predominantly low grade metamorphism. The area is now considered to be a 500 million year old active, continental margin.1 As is typical of most of the piedmont, outcrop is sparse. Figure 2 is a sketch map of the general geology of the area under study, showing the Charlotte belt rocks in the northwestern quadrant and slate belt rocks, to the east. Within the area are a number of old mines and prospects, the most famous of which are the Furniss and the Phoenix mines in Cabarrus County. All are reported to have contained Au and Cu. Ag and Pb were reported from some. A summary of the deposits is given in Table 1. Data used in this study are from three Master's theses conducted at the University of North Carolina at Chapel Hill. 3,3,6 In separate studies, well waters5, B-zone soils3, and vein and float quartz6 from the area described were sampled and analyzed. Each study concluded separately that geochemical anomalies in the vicinity of the ores justify use of that specific sample type in a geo-chemical exploration program. However, no comparative study of the methods has

Jan 1, 1977

By P. G. Corser

A gold and silver open-pit mine located in northwestern Chile contracted ACZ in 1991-92 to assess the stability of their spent ore pile and to determine the cause and magnitude of cyanide contamination associated with leaching operations. The mine is a conventional open-pit located at an elevation of approximately 4,800 meters (m.) (15,744 feet). A spent ore pile is located approximately 2,000 m. southwest of the mine and approximately 1,000 m. northeast of the active pad and plant facilities. The pile was constructed on a gentle northwest slope dipping 12 to 13 degrees. The pile is bordered by a small river to the northwest and by a larger river to the northeast. Both rivers eventually flow into Bolivia. Heap leaching and processing commenced at the mine in 1988. Since 1988, nearly 6.0 million tons of ore at an average grade of 1.96 grams/ton (0.07 ounces/ton) of gold and 52 grams/ton (1.83 ounces/ton) of silver have been treated by cyanide heap leach methods with zinc (Merrill Crowe) precipitation. In approximately three years of operation, the mine has yielded more than 225,000 ounces of gold and over 1.5 million ounces of silver. Currently ore is agglomerated and hauled to the leach pad by truck and is top loaded to produce a 5-meter lift height. Four contiguous reusable (on/off) leaching pads were constructed with an asphalt layer above a carefully compacted sub-base of High Density Polyethylene (HDPE) liner and screened fines. Leach solution of pH 10-11 containing 1.2 to 1.5 gram/liter of cyanide is applied to the heap at a rate of 10 liter/hour/square meter for a total active application period of 30 days. Leached (spent) ore is transferred to the spent ore pile located approximately 1,000 meters to the northeast. The pile currently contains approximately 6 million tons of spent ore. The pile liner, which has been constructed over a prepared sub-grade consists of three geosynthetic layers (geotextile/flexible membrane liner/geotextile). Long term objectives include washing the pile to recover an additional 3 to 4 percent gold and silver.

Jan 1, 1993

By D. A. Peterson

A research program is currently in progress at the University of British Columbia to determine the potential of composite cable bolt reinforcement in Canadian mines. Several prototypes of glass fibre cable bolts have been tested. Their evaluation consisted of lab testing at the University of British Columbia, United States Bureau of Mines (Spokane) and trial installations at Detour Lake, Winston Lake, and Myra Falls Mines. A market analysis of cable bolts within the Canadian mining industry has been completed. Fibre reinforced polymer composites have a high potential as cable bolt reinforcement in mining applications. They prove to be a viable alternative to steel cable bolting.

Jan 1, 1993

By Eva K. Fernandez, Paul Y. Louie, Derek S. Adams, Renée L. Fippin

The Folsom Area Stormwater Improvement Project is part of SFPUC’s flood resilience efforts under the Sewer System Improvement Program. This 4,000-foot-long, 12-footinside- diameter tunnel will help reduce the risk of flooding in San Francisco’s low-lying Inner Mission neighborhood. The project is in a high seismic hazard zone and extends through a complex geologic corridor that includes full-face soft, compressible Bay Mud, Colma Sands, and full-face rock with several stretches of mixed-face conditions. Additional challenges include removal of 99 piles beneath an existing box sewer, tunneling under commuter rail tracks, and an underground tie-in. This paper examines these challenges and how they are being addressed.

Jun 13, 2023

By Allan R. Ide

It is a great pleasure for me to speak-before such a prestigious group as the American Institute of Mining, Metallurgical and Petroleum Engineers. The substance of my talk today is the handling of coal and petroleum coke: their characteristics and environmental problems, and how we were able to correct the problems, prescribe the cure and enjoy the benefits. When coke first became a by-product derived from the oil refineries everyone would have been very happy if someone had offered to take this pro- duct off their hands. Unfortunately, there was no market at that time, and no one seemed interested. Soon thereafter, it became a sellable product and began to be shipped to many countries in the world. This was when all of the pollution problems began. I will be talking briefly about some of these problems and showing a short film on this subject afterwards.

Jan 1, 1984

By I. F. Walder

Mill tailings from skarn-type base metal deposits were studied in order to ascertain potential element mobility in response to weathering. Hypogene ore minerals are sphalerite, galena, and chalcopyrite, showing minor supergene oxidation to smithsonite, cerussite, and covellite. Gangue minerals are pyrite, pyrrhotite, magnetite, hematite, andradite and grossular gamet, hedenbergite, calcite, ankerite, and quartz. Foremost of the eleven tailing piles studied, the hypogene sulfide minerals show no or only incipient post-mining oxidation. Iron oxides and hydroxides form the main oxidation products in the tailings and are enriched in heavy metals. A distinction between pre-and post-mining oxide phases may be obtained based on petrographic observations which distinguish whole-grain versus partial grain replacement. Zn and Cd do not appear to be enriched in the weathering derived oxidation minerals and will be more easily leached from the tailings than other metals.

Jan 1, 1994

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

By William J. McCutheon

This paper presents some personal observations obtained during the course of visits to Europe, Africa, Latin America and the United States to talk with senior decision-makers in the copper industry about their views of markets, prices and the future of copper. The industry's future has never been particularly easy to define; with the changes of recent years, prediction has become even more difficult. The author's personal assessments of the present and future are offered for comment.

Jan 1, 1986

By Jung-Hum Lee, Young-Joon Lee, Eui-Joon Hong, Seon-Hong Kim, Chan-Dong Kim, Keon-Woong Jeong, Ki-Lim Kim

"Subsea tunnel needs to be built over 50km long to connect between nations and continents. However there are only 19 tunnels longer than 5km in Korea, and there is no history of constructing and operating a tunnel longer than 50km. As the concept of a subsea tunnel, which withstands high water pressure and has an extremely long length is completely different from that of a land tunnel, all kinds of the latest technologies for tunnel construction are required such as survey and analysis of geology, design and construction under high water pressure, ventilation and prevention of disasters within an ultra long tunnel. Therefore, this paper describes the determination of tunnel cross-section under a high speed railway, structural stability, ventilation and fire safety under construction and operation, etc. through the virtual project for the length of 108km subsea tunnel under high water pressure of maximum 20bars from Honam to Jeju island in Korea. 1. INTRODUCTION The Honam-Jeju virtual project is subsea tunnel project to link from Honam(land) to Jeju(island) extending the currently operating Honam high speed railway line, and the same express train(t=18, design speed 350km/h, total train length 200m) operating at Honam line is applied in this project. As Honam-Jeju site is approximately 80km in straight distance with 160m maximum depth, subsea tunnel project should determine the various issues such as air quality/ventilation, aerodynamics, temperature, drainage, fire & life safety, structural stability. Figure 1. is the plan of subsea tunnel, with be constructed using Shield TBM. This double tube-Single track is composed of cross passages (every 350m in general section and 40m in emergency station), service tunnel, pressure relief ducts (every 250m), cross-over tunnels, shafts and emergency stations. 2. ALIGNMENT AND SITE CONDITON This project is planned as an ultra long tunnel of total length more than 105km via existing islands between Honam and Jeju island because straight alignment requires an artificial island which has high cost and construction risk, by deep water depth, though this is the shortest distance (see Fig 2). Water depth and topography in project site is divided into two blocks by Chuja Island. In first block to Chuja Island, depth of the water is 40m on average and maximum 60m, which indicates gradual change of water depth relatively. Also, outcrop bedrock is widely distributed near island."

Jan 1, 2016

By C. A. Rowland

Autogenous grinding, defined as grinding with like material, while quite an old art has recently been revitalized. Two phases of autogenous grinding, primary and secondary, have been the subject of recent papers, technical articles and discussions. The purpose of this paper is to discuss a third phase of autogenous grinding - Intermediate Autogenous Grinding - comparing it to and indicating advantages over the other two phases. Autogenous grinding can also be called ?Rock grinding?1; that is, grinding using ore or rock from the same deposit as the mill feed as grinding media contrasted with using as grinding media steel rods, steel or ironballs, natural or manufactured iron, free pebbles, or other shapes and materials foreign to the mill feed.

Jan 1, 1964

By C. D. Keith

Erie Mining Company, a pioneer in the iron ore pelletizing industry, has continued to develop methods and equipment to improve cost and quality. Under the management of Pickands Mather & Co., this property, owned by Bethlehem Steel Corporation, Youngstown Sheet and Tube Company, Steel Company of Canada, Ltd., and Interlake, Inc., has initiated a number of operating improvements for the taconite industry. One of the most noteworthy of these, which is applicable to the entire mineral industry, is the principle of fine screening with rappers (FSR). Erie's original efforts in the field of fine screening, which date back to 1961, were described in the April 1967 issue of the MINING ENGINEERING magazine. In that same month, Erie placed into operation a full scale PSR and regrind plant addition, capable of processing 10.3 million long tons of iron ore concentrates, produced by conventional taconite grinding, classification, and magnetic separation methods. Since this first successful commercial operation of the PSR principle et Erie, it has been applied in eight other iron ore beneficiation plants end is being tested by other U.S. and foreign companies. In addition to the use of PSR units at Erie Mining Company, Pickands Mather has applied PSR to other of its managed properties end to projects under development. This paper covers these applications as well as a now application at Erie Mining Company.

Jan 1, 1971

By Alix Thierart, Yann Rouillard, Bernard Catalano

Bessac's presence in Singapore started in 2014 with the construction of the Thomson metro line, which includes 18 miles of twin-bore tunnels and 22 stations split into 17 construction packages. Bessac joint venture was allotted the T219 lot. The works include the construction of a new 660-foot (200-meter) long transfer station, two parallel 19-foot (5.8 m) ID tunnels and a pedestrian underpass. The urban context and the very soft ground stratum imposed to utilize unusual tunneling techniques, from upgrading a slurry TBM to a high-density slurry TBM to launch with very low cover and canopy pipe roofing completed with a MTBM without retrieval shaft.

Jun 23, 2024

The criteria used to design, operate and control flotation columns are significantly different from those used for conventional flotation machines. Therefore, a computer-aided design (CAD) package for column flotation has been developed. The simulator has been set up using guidelines developed at Virginia Tech and information published in literature during the past few years. The simulator is useful for determining the proper design and appropriate operating conditions for a column cell to fit a specific set of conditions. In addition, the simulator can be used for training in column operation and for trouble-shooting operational problems. Simulation results have been found to be in good agreement with experimental data obtained using laboratory columns.

Jan 1, 1990

By Andrew B. Pervis

With the ever increasing demand for Finer powders by industry there has been a continuing effort by air classifier manufacturers to improve and offer machinery capable of producing these fine powders. Common to these classifiers is the use of a multivaned rotor through which passes all of the air used to transport the particles to be classified. Rotor revolutions per minute and the amount of air passing through the rotor are the main variables in determining the particle sizes which will be able to pass through the spinning rotor. A simplified equation derived by setting the air drag force carrying a particle through the rotor equal to the centrifugal force due to the spinning rotor's action on the entering air and particle is: Diameter of Particle = [ ] Where K is a function of air viscosity, particle configuration, rotor and blade configuration; RPM is rotor revolutions per minute; M3/sec. is air quantity passing through the openings between the rotor blades.

Jan 1, 1983

By W. J. Bronkala

Dense-medium circuits have been installed in many mineral treatment plants since its, original development about thirty years ago. In the intervening, period the process has been thoroughly evaluated and many innovations have been introduced. The Heavy Density. Cyclone is one of the newer systems which has extended the operating range of this process to 65 mesh size. Several different finely divided materials have been used to produce the separating bath but nearly all new plants use a ferro-magnetic medium. The, advantages of magnetic medium include: 1. Smaller recovery plant 2. Lower cost recovery plant both in initial and operating cost 3. Excellent medium stability 4. Dependable medium supply at reasonable and stable cost. Magnetic separators are used to recover this magnetic medium and the smaller plants and lower operating costs are directly related to their use.

Jan 1, 1964

By Ch. R. V. S. Nagesh, Ramesh Naidu Mandapati, Venkata Swamy Nalajala, Tondepu Subbaiah, Naga Jyothi Kothamasu

Leaching studies of magnesite obtained from Tamilnadu Magnesite Limited, Salem, have been carried out using hydrochloric acid leaching and percentage of magnesium chloride recovered was estimated. The variables considered in this study were the following: duration of leaching, volume percentage of hydrochloric acid, temperature, and pulp density. Percentage recovery of magnesium chloride increased with duration of the leaching, volume % of concentrated hydrochloric acid, and temperature. Percentage recovery of magnesium chloride decreased with increase of pulp density. The optimum conditions found to be pulp density (10%), hydrochloric acid concentration (30%), duration of leaching (2 h), and temperature (348.15 K). Iron was removed by treating the leach liquor with hydrogen peroxide and by raising the pH to 3.5–4. The purified leach liquor was subjected to spray drying for producing high pure magnesium chloride.

Jun 7, 2022

By Steve Kral

When discussing stock market investments, a company's performance is important. But so is the financial community's perception of that performance. To be sure, a good product or service, coupled with sound manage¬ment, remains important but is no longer enough. How stock analysts view a company's performance has become equally important. A major task of a mining company's investor relations officer, then, is to build and maintain a positive perception of the company to mining analysts throughout the world. That's a tough assignment in any market. The subject here, though, is gold. And, with its weakened price, gold companies must work harder to convince analysts their company is still a good investment. The analyst, on the other hand, must see through the corporate hype and decide whether it's worth recommending to clients as an investment. No simple task, either. Annual reports, 10-K forms, and quarterly reports only tell part of the mining company's story. Site visits, complete with discussions (sometimes interrogations) with a mine's principals, oftentimes tell an analyst more about a company's investment potential than the annual or quarterly report. So it was that three of the nation's major gold companies arranged a three-day tour of their gold operations in Nevada for a group of 22 analysts and a pair of mining industry scribes. The analysts represented investment houses the US, Canada, and England. The host companies and mines visited included FMC Gold's Paradise Peak mine, Amax Gold's Sleeper and Wind Mountain mines, and Battle Mountain Gold's Surprise and Fortitude mines.

Jan 1, 1989

By Vincent Tricot, Daniel Altier, Roger Storry

"INTRODUCTION The Liantang / Heung Yuen Wai Boundary Control Point (BCP) project, located in the north-east New Territories of Hong Kong, will form the seventh land crossing between the Hong Kong Special Administrative Region (HK) and Shenzhen in China (Figure 1). The BCP project comprises an 11km long dual two-lane trunk road linking the border crossing facility to the existing road infrastructure in HK and when completed it will facilitate future regional development and alleviate frequent traffic congestion at the existing Boarder control points.In December 2013 Dragages Hong Kong (a member of the Bouygues Construction Group) was awarded the 5.4km long Contract 2 section of the project, including the 4.8km long Lung Shan Tunnels, by the Civil Engineering and Development Department of the Government of the HK SAR. To overcome the difficult ground conditions anticipated along the Contract 2 section of the project the tunnels will be constructed using mechanical and drill and blast (D&B) excavation techniques together with a 14.1m diameter multi-mode Earth Pressure Balance Tunnel Boring Machine (TBM). Land constraints imposed on the project alignment require that the final 500m section at the northern end of the Lung Shan tunnels, under Princess Hill (Figure 2), takes an almost 90 degree turn towards the north. The resulting 354m radius curve restricts the sight-line of road users to below the minimum 110m at 80km/hr hence, the internal span of the tunnels needs to be increased from 12.6m, in the standard straight section, to 15.4m in this curved section to accommodate a widened shoulder which will provide the required sight-line distance."

Jan 1, 2016