Search Documents

By D. Craig Camp

Microtunneling has successfully completed both horizontal and vertical curves. This paper covers the historical development of curved microtunneling and a description of one microtunneling project. The completed microtunnel is used for electrical transmission in Japan. The crossing had several concerns including right of way, social disruption, obstructions, the cost of intermediate shafts, and political restrains. In order for this drive to meet all of the imposed restrictions, four horizontal curves and one vertical curve were planned and executed in accordance with the design. Iseki Poly-Tech of Tokyo, Japan designed and built the microtunneling machine to meet the project requirements. Curved microtunneling has been successfully used on fourteen projects in Japan. The reason for a curve has been that the project could not be rerouted, short straight drives could not be used to negotiate the curve, or the project’s social and environmental conditions required a curved tunnel. The following table (Table 1) includes summary information on 14 curved microtunnling projects that have been successfully completed in Japan. The first column is a reference number. Columns two through four include basic project information. The fifth column is the total project distance completed by microtunneling. The sixth column is the project’s microtunneling duration. The seventh column is the machine type and size. All of the machines listed are manufactured by Iseki Poly-Tech of Tokyo, Japan. The size is the internal concrete pipe diameter; all of the projects listed were completed with Japanese standard concrete pipe. The eighth column contains a general description of the soil. The soil type and blow counts are approximately equal to ASTM D 2487 standards. The ninth column lists the radius of the curve and the span distance or the distance microtunneled that included the curve. The radius of a vertical curve is denoted with a “VR”, a span with both a left and right hand curve is denoted with a “S”. Other significant first events are also noted in this column. The first curved microtunneling project was completed in 1982 using a conventional microtunneling machine with standard Japanese concrete pipe and a very long radius curve while maintaining grade for the gravity sewer. The second curved microtunneling project included multiple radii curves, all in the same direction, on a single drive. In 1989, on the fifth curved microtunneling project, a “S” curve was successfully negotiated. On the seventh curved microtunneling project, completed in1995, a tight radius curve was negotiated. In 1996, the eighth project included a vertical curve. The thirteenth curved microtunneling project, completed in 1997, was the first project to utilize a microtunneling machine specifically designed to negotiate curves. The fourteenth curved microtunneling project was the accumulation of all

Jan 1, 2001

By R. D. Bartlett

Large open pit mines in desert climates, such as the Phelps Dodge Morenci copper mine in Arizona, can create groundwater cones-of-depression of considerable size and :ability. The hydraulic containment provided by the groundwater depression prevents migration of process solutions into the surrounding regional aquifer. Copper leach operations that fall within the groundwater depression may not require costly lining if passive containment can be demonstrated. An approach is presented in this paper that was successfully used to demonstrate passive containment. The approach includes a combination of groundwater modeling and a water balance analysis of leaching operations failing within or immediately near the open pit.

Jan 1, 1999

By Suresh K. Bhatt

A mathematically simulated modeling technique is used in this U.S. Bureau of Mines paper to represent a hypothetical mining operation with existing mining technology and prevalent mining costs. Mining scenarios are prepared and evaluated for potential benefits and costs available through computer-assisted mining. Base criteria, parameters, and methodology are described.

Jan 1, 1991

By P. R. Taylor

The ability to process complex precious metal sulfide concentrates containing antimony and arsenic in an economic and environmentally safe manner is an important problem facing the mining industry in the United States. Preliminary experiments have been performed to evaluate the possibility of treating a complex sulfide concentrate to recover antimony and precious metals while fixing the arsenic and sulfur as calcium arsenate and calcium sulfate. The process involves: • the oxidation of the antimony and arsenic minerals in the presence of soda ash (to collect the sulfur dioxide and to keep the antimony and arsenic from forming volatile compounds), •the selective leaching of the arsenic from the roast calcine with a heated caustic solution, •the precipitation of the arsenic and sulfate with calcium hydroxide and/or calcium chloride, •the reduction of the residual antimony (collecting the precious metals), •fuming of the metal to form a marketable antimony oxide, and •crucible reduction of the residue to obtain a gold and silver dore. Batch experiments, using synthetic concentrates of stibnite and arsenopyrite, were performed to evaluate the first stage of this process. Variables studied included mixture weight fractions, temperature, gas flow rate, oxygen partial pressure, and time. All of the off gas dust and sulfur containing gases were collected and analyzed. The roast solid residues were subjected to arsenic leach tests, and the leach solutions were subjected to arsenic and sulfate precipitation tests. Introduction The ability to treat a precious metal ore containing appreciable amounts of antimony and arsenic is dependent upon the characteristics of the ore. For some ores, selective flotation can be used to separate the antimony and arsenic minerals, which are then treated separately. Unfortunately, many ores are not treatable in this way, and the concentrates obtained may contain appreciable contamination (which limits the ability to make acceptable grade antimony products). If we consider the added value of the precious metals in the concentrate, then it is worthwhile to evaluate the potential for new methods to treat these types of concentrates. In addition, the environmental difficulties associated with arsenic disposal must be taken into account in any proposed process. If there is appreciable arsenic present, then it must be either recovered as a marketable product or placed in an insoluble form. The problem addressed in this research program has become increasingly important as the precious metals mining industry is encountering more ores of this type. A large deposit of this type exists in Idaho where the antimony occurs primarily as stibnite, with minor amounts of kermesite and tetrahedrite (Cooper, 1951). The gold appears in association with arsenopyrite with minor amounts of other arsenic minerals. Flotation has been used to obtain an antimony concentrate. The concentrate, however, is contaminated with appreciable amounts of arsenic and also contains precious metals. If the ore or concentrate contains appreciable amounts of base metals, then the recovery process becomes much more difficult. There are a number of other known deposits of this type in Alaska, Canada, Montana and elsewhere. The objective of this research program was to develop a fundamental understanding of the oxidation and leaching chemistry of the arsenic and antimony minerals so that technology may be developed to treat these ores in an economic and environmentally safe manner. Wendt (1949) and Koster and Royer (1940) discussed the possibilities of oxidative roasting of stibnite concentrates containing arsenic. Wendt describes a process used at a smelter in Czechoslovakia (in the 1930s) where roasting was carried out in rotary furnaces at 723° K (500° C). Most of the arsenic was removed as fume, as well as 25% of the antimony. No sulfur dioxide containment was described. The oxide fume from the furnace went to a heated caustic water leach, where the arsenic was preferentially dissolved and then precipitated with calcium chloride as calcium arsenate following solid-liquid separation. The antimony oxide was sold, and the solid oxide discharge from the rotary furnace was sent to a blast furnace where the antimony metal, containing the precious metals, was recovered. The metal was fumed to obtain antimony oxide, and the precious metals were left in the residue and collected with copper. The copper

Jan 1, 1994

By N. M. Cheimanoff

GEOCAD is an ambitious research program aimed at the development of a computer based system assisting the geologist and the production or planning engineer. BONANZA, its mining part, is a computer production scheduling tool (short to medium term) of particular relevance to complex orebodies. The principle is to simultaneously use a powerful information management system (CAD potentialities) and small expert modules integrating the exploitation context and the engineer's knowledge (Artificial Intelligence tecniques). As an illustration, a module of mineable block determination for underground exploitation is discussed.

Jan 1, 1989

By Michael G. Nelson, Brandon J. Peterson

Currently, decisions made by mine management are usually based on economic analysis and predetermined rating systems and tables. As financial and other constraints on mining operations become more severe, more accurate methods are required. Discrete-event simulation programs have been used successfully in many mining applications, including the simulation of open-pit, truck-and-shovel operations. However, these simulations could not model complex systems well enough to provide the detailed modeling of the haulage roads and other mining operations that is needed today. The recent advances in computing technology combined with the recent abilities of simulation to realistically simulate complex systems and visually present results in 3D have made simulation a more detailed and valuable aid in the evaluation of mining projects.

Jan 1, 2002

By Edward M. Dowey

This paper presents the excavation of the Roosevelt Island Valve Chamber, the final of three chambers in Stage One of New York City's Third Water Tunnel. The valve chamber and passageways 13 379.7 cu m (17 500 cu yd) are drilled and blasted. The rock is stabilized by grouted rock anchors. The 6.1 m (20 ft) diameter shaft is drilled, blasted, rock bolted and wire meshed for a depth of 70.7 m (232 ft). Then shaft excavation proceeds with immediate concrete lining for another 120.7 m (396 ft). Two 6.1m (20 ft) diameter manifolds are excavated using heading and bench. The raise drilling of eight 3.7 m (12 ft) diameter laterals occurs during lower shaft sinking.

Jan 1, 1987

The visible portion of accounting-record keeping and preparation of financial statements-suggests a lack of sophistication and imagination. In reality, accounting is based on a large body of theory. Accountants philosophize, theorize, judge, create, and deliberate as a significant part of their professional practice. The subjective aspects that are so critical to current accounting practice, such as searching for truth and fact, judging what is fair presentation, and considering the behavior induced by presentations, are often overshadowed by the appearance of exactitude, precision, and objectivity that accompanies the use of numbers to express the financial results of the enterprise. * Fundamental accounting principles are hypothesized in the same manner as mathematical principles. These principles are justified by acceptability and intuition. Accounting theory is built upon these hypotheses, resulting in a coherent set of standards and rules. Although it does not specifically address every situation that may be encountered, this conceptual frame- work enables the manager or analyst to resolve specific situations. This framework also aids in the understanding and confidence in financial statements and ensures comparability between statements from different companies. This framework is referred to as "generally accepted accounting principles," or GAAP.

Jan 1, 1999

By D. Carr, C. Anderson, M. Deal, C. Larson

"Construction of the OceanaGold Haile operation’s process plant in Kershaw, South Carolina is currently under way, with ore through the mill expected in late 2016 and commercial production expected in early 2017. The process is designed to treat 6,350 tonnes per day with minor upgrades required to achieve 8,270 tonnes per day. Plant optimization during detailed engineering, combined with a focus on de-risking the process, has resulted in numerous process changes since the initial design. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio operation, whilst identifying potential expansion opportunities. INTRODUCTION Haile Gold Mine is located in Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The last operation employed heap leaching from 1985 through 1992. Since then, the property has been closed and fully reclaimed. Romarco Minerals acquired the property in 2007, and began an exploration program that delineated 2.02Moz. of gold in reserve at an overall grade of 2.06 g/t. OceanaGold acquired Romarco Minerals and the Haile Operation in October of 2015. OceanaGold operates under a risk management philosophy in all aspects of operation, both corporately and at each individual business unit, and has implemented numerous process changes to eliminate or mitigate risks identified in the initial design of the processing circuit, and provided increased opportunity for optimization and expansion. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio Operation, and identifies potential expansion opportunities. INITIAL PROCESSING CIRCUIT DESIGN An extensive metallurgical test work program was undertaken by Romarco Minerals and third party laboratories during the initial design phase of the Haile project [1]. This preliminary test work provided the technical information as a basis of plant design. The initial flow sheet for the Haile processing circuit is shown in Figure 1 (see APPENDIX). The plant is designed to process 6,350 tpd (7,000 stpd) on an annualized basis. The process begins with a jaw crusher followed by a SAG and ball mill grinding circuit to reduce particle size to P80 74 µm. A flash flotation cell treats 50% of the cyclone underflow in the ball mill circuit. Grinding circuit product is sent to a rougher flotation circuit to recover gold-bearing pyrite. The flotation concentrates from flash and rougher flotation are reground to P80 13 µm using stirred media detritors (SMD’s). The rougher flotation tail is pumped to the carbon-in-leach (CIL) circuit for gold recovery. The reground concentrate is pre-aerated prior to being pumped to the CIL circuit. The CIL circuit is a hybrid circuit with eight tanks. Tank 1 leaches the pre-aerated concentrate only, and tanks 2 through 8 leach the combined flotation tailing and tank 1 discharge. The carbon strip circuit is a standard pressure Zadra system, followed by electrowinning, and refining using an induction furnace. CIL tailing passes through a cyanide recovery thickener prior cyanide destruction and then pumped to the tailing storage facility (TSF)."

Jan 1, 2017

By McDonald E. Wrenn, Narayani P. Singh, Victor E. Archer, Ceno Saccomanno

Fourteen uranium miners' lungs from Colorado plateau were collected at autopsy and the concentrations of 238U, 234U and 230Th were determined by radiochemical procedures utilizing solvent extraction - alpha spectrometric techniques. The uranium and thorium isotopes are in near equilibrium with average concentrations of 238U, 234U and 230Th being 89.3, 95.2 and 91.1 pCi/kg respectively. The combined average radiation dose rate to lung from these three isotopes is about 24.2 mrad/year at death excluding the unmeasured contribution from the 226Ra and daughters. The average concentration of 230Th is about 65 times higher than the mean concentration of 230Th in lungs of non-miners dying at comparable ages from the same region.

Jan 1, 1981

By R. C. Keaney

The metals industry is in complete chaos with mines being shut down, profits becoming non-existent, and continual losses to imports from other countries. Yet the raw material supplier to the glass industry has many opportunities to grow and to produce profits. Fortunately, the cost of most glass raw materials are low enough that competition from imports is not anywhere as critical as it is in the metal industries, such as copper, aluminum, lead, and others. But the glass raw material supplier must develop new products, both chemically and physically, to effectively compete in the future. The purpose of this paper is to point out generally where these opportunities exist and to suggest how they may be further developed. As the glass industry looks for energy saving materials, they look once again towards finer materials. A glass furnace is now approximately 40% efficient. Glass engineers are constantly striving for energy savings and it is well known that finer materials melt easier so that the manufacturer can operate his furnace either at lower temperatures for the same production or he can produce more material at the same temperature. The old 20 mesh sand specification is no longer sacred and as the mesh size for sand changes so do the specifications for all other raw materials used in the melting process. Highly instrumented glass furnaces can now measure quite accurately the energy needs to produce glass and can also measure the energy loss in each furnace. Glass technologists desire today a sand with a top size of 40 mesh while some would like to have the top at 60 mesh. This becomes more difficult to accomplish as a raw material supplier without .grinding. As you well know, grinding develops fines. Yet the same technologists will tell us that we can have nothing passing a 140 mesh screen. Therefore, we must develop processes which allows us to produce a finer screen size without increasing the amount of fines passing through the 140 mesh screen. To counteract this, different and changing industries are now demanding much finer products so possibly there will be markets for the fines which are currently separated out of the products. Methods that are practical and low cost must be found to develop different products with different screen specifications. What works for sand can be carried over to the other raw materials used in melting. Among the answers to finer products, of course, are pellets. Aglomeration or pelletizing has been looked at in the past and will be looked at in the future. Considerable work has been done in the glass container industry on this and must be carried out more extensively. By using aglomerated material or pellets, the glass producer will gain the benefits of melting fine materials without suffering from handling or dust problems. Pelletizing, particularly where using basic glass melting materials such as burned lime or sodium silicate, will not only produce a good pellets but will add desirable minerals to the glass batch.

Jan 1, 1986

By J. L. Kohler

The knowledge-based expert systems (KBES) is a potentially powerful technique to the mining engineer in traditional areas of mine design and operations, as well as in the emerging areas of mining automation and robotics. Since KBES is still experimental in many respects, caution must be exercised as this "high tech" tool is developed and applied to mining. The objective of this paper is to demystify expert systems by introducing the elements of KBES, discussing the strengths and weaknesses, and identifying some areas of application in mining, based on the authors' experiences.

Jan 1, 1986

By M. Paventi, M. J. Scoble, B. B. Mohanty

There is no straightforward and systematic method for adequately measuring blast damage in on-going mining operations. This paper considers various techniques available for the measurement of blast damage, making particular reference to recent underground hardrock mine studies. This paper concludes by indicating the importance of understanding and accounting for geology and emphasizes the need for a robust damage-audit procedure.

Jan 1, 1998

By B. Jensen, B. K. Abraham, G. J. Tuck, A. D. S. Gillies

A dust concentration meter has been developed with Australian coal industry support for the measurement of total airborne dust concentrations capable of causing explosions in underground coal mines. The instrument, The University of Queensland Dust Meter (UQDM), measures the effective dielectric constant of a mixture of coal dust and air that is drawn between the plates of a capacitor, the capacitance of which is measured by a ratio-transformer bridge and synchronous detector system. This technique measures small changes in capacitance to approximately 1 part in 106. The unique design of the capacitor sensor permits a precise volume of coal dust and air mixture to be sampled. This arrangement overcomes difficulties inherent in optical dust measurement. The meter is portable, battery powered, incorporates data logging and has intrinsic safety approval. The operation of the meter is discussed. The system is designed to monitor dust concentrations along a coal mining face and provide concentration profiles leading to the development of suppression strategies. If data from underground tests are available, the meter's potential to contribute to establishing safe working conditions underground will be discussed. Other areas of potential application of the measurement technique are also examined.

Jan 1, 1993

Introduction One hundred years ago, a recent college graduate created the US aluminum industry. He found an economic way to crack the primeval bond that makes the metal so special. Aluminum doesn't "rust" - oxidize progressively. Rather, when exposed to air, it instantly forms a gem-hard but microscopic oxide coating. This seals off oxygen from the metal underneath. Scratch it and the seal reforms instantly. That tight chemical bond is the reason the metal is not found in nature; it exists only as a compound. The bond had to be broken to free the shiny metal. But once it is free, that self-sealing protection, alongside a remarkable strength-to-weight ratio, offers a marvelous material. Until 100 years ago, finding a way to do that economically was a challenge that defied science. Then it was solved, in a remarkable coincidence, on both sides of the Atlantic. And the way was paved for a material that would become the second most widely used metal in the world. Until that time, aluminum was a rare and precious metal. But then two young scientists independently invented the process that took aluminum outside the laboratory and into applications ranging from pots and pans to spacecraft. Discovery of aluminum Other major metals - copper, iron, lead, gold, and silver - had been used for thousands of years. But aluminum was entirely unknown until 1782, when French chemist Antoine Lavoisier suspected its presence. It was not actually discovered until Sir Humphry Davy, in England, detected it in clay in 1807. It was first isolated as a free metal only in 1825, by Denmark's Hans Christian Oersted. For years, laboratory methods yielded aluminum only in tiny amounts costing about $1200/kg ($545 per lb) - $13,333/kg ($6000 per lb) in today's dollars. Methods developed by French scientist Henri Sainte-Claire Deville in 1854 cut the cost to about $200/kg ($90 per lb). King Frederick VII of Denmark had a helmet of aluminum and gold. And Emperor Napoleon III of France reportedly served his most exalted guests at a state dinner with aluminum plates. He left the lower ranks to dine from pure gold. Deville and others continued to reduce production costs. But the price of aluminum still rivaled silver - $31/kg ($14 per lb) versus about $35/kg ($16 per lb) for silver. Then in 1884, a 2.8-kg (6.25-1b), 230-mm-tall (9-in.-tall) aluminum pyramid was cast as the tip of the Washington Monument. It was probably the first architectural use of aluminum. And it is still there after more than a century. The attractive properties of aluminum were obvious: it is lightweight but strong, conducts heat and electricity, reflects light and other electromagnetic radiation, and resists corrosion. But its commercial promise was blocked by its cost. In 1885, the price of aluminum was $17.70/kg ($8 per lb). It stayed there for the next couple of years until the Hall-Heroult process brought it down sharply. Hall-Heroult process lowers aluminum costs The characteristic that kept aluminum hidden so long continued to thwart chemists. Aluminum clings to oxygen so tightly that it is never found as a free metal in nature, and it is hard to break that bond chemically. The best chemical methods of the 1880s required sodium, and sodium itself was expensive. At Oberlin College in Ohio, chemistry professor Frank Fanning Jewett advised his students that anyone who could make aluminum inexpensive would do humanity a favor and get rich as well.

Jan 3, 1987

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017

By G. R. Denham

Innovative designs, mining, construction and reclamation practices are used at PT Newmont Nusa Tenggara's Batu Hijau mine on Sumbawa Indonesia to develop a cost-effective, environmentally sound, stockpile and dumping system. The mine production rate is over 200 million tonnes per year (50 million tonnes processed with 150 million tonnes being stockpiled for processing later or placed in waste dumps). Dump development for over 150 million tonnes per year in a mountainous, tropical environment, while meeting environmental and permitting requirements is not an easy task. The effective implementation requires innovative techniques and practices from every department of the mine.

Jan 1, 2002

By M. W. Harmer

Laboratory test work, pilot plant testing and plant experience with wet, fine mesh screens is discussed. High frequency, low amplitude, fine mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with 'hot ferric chloride to remove Pb and Cu contaminates before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1990

By J de Cuyper, G. Rinelli, A. M. Marabini, V. Alesse, W. Freyberger

Salicylaldehyde, a chelating agent for tin, has been found to function as a collector for the flotation of cassiterite. Infrared and nuclear magnetic resonance studies clearly show that salicylaldehyde can form a chelate compound in bulk and at the surface. Results are also given for the flotation of a tin ore with this reagent.

Jan 1, 1976

By J. Payton

Public Service Company of Oklahoma began burning sub-bituminous coal in December, 1979. Initially PSO had a single source coal supply from Jacobs Ranch Mine, and in 1982 added deliveries from Clovis Point mine. Both are Powder River Basin (Wyoming) coal mines. In 1986 PSO began burning Oklahoma coal to meet Oklahoma's 10% native use law. PSO experienced random s lagging during certain blends of these coals. PSO installed a boiler performance system to help control the slagging problems from the various coal blends, to improve boiler efficiency, and increase total coal consumption.

Jan 1, 1990