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By MAURICE SUNKPAL, Taghi Sherizadeh, ELAHEH TALEBI, PEDRAM ROGHANCHI

Excessive heat exposure is among the health and safety hazards for mine workers. The nature of the underground climate makes it a convenient avenue for heat generation and accumulation from several heat sources, including autocompression, equipment and heat from strata. This study investigates the effects of clothing insulation and acclimation on the thermal comfort of mine workers exposed to heat in underground working environments. Several clothing ensembles were considered to analyze the effect of the thermal resistance of clothing on the workers’ thermal comfort. To investigate the impact of clothing insulation, the thermal comfort limit of an underground miner was calculated in the form of maximum allowable exposure time for an eight-hour shift.

By Pentti Seppanen

The activities of Outokumpu Oy in the mining industry span all branches from prospecting to the production of refined metals and the manufacture of semifinished products. Products include copper, zinc, mercury, cadmium, nickel, cobalt, sulfur, gold, silver, iron ore, stainless steel, selenium, ferrochromium, lead and chromium concentrates, as well as chromite foundry sand. In addition, the activities of Outokumpu Oy extend to development and production of instruments, planning of industrial projects and instrumentation as well as the manufacture of specialized machines for ore concentration. The company now operates ten mines, eight of which are underground and all of which are in sulfide deposits except one. The fully automated monitoring and control of underground mine ventilation at the Pyhasalmi mine are an important technological contribution to the industry. Development work on the ventilation control was started in 1969, and since May 1973 it has operated in a fully automated computer-controlled mode. The Pyhasalmi mine has been in production since 1962, having begun as an open-pit operation. Development of underground mining began in 1967. The present annual production is one million tons all from underground mining. The underground mine is equipped with a main shaft and an auxiliary shaft, and two raises for ventilation. There is also a rampway from the surface to a depth of 500 m. The main shaft is for ore hoisting and the auxiliary shaft is used for waste-rock hoisting and for downcast ventilation. One of the raises is for downcast ventilation and the other is for upcast ventilation. The mining methods employed at Pyhasalmi are sublevel stoping with backfill, sublevel caving, and sublevel shrinkage stoping. Copper and zinc concentrates are produced. The Pyhasalmi mine is highly mechanized with about 4000 installed diesel horsepower underground. The maximum capacity of fresh air is 150 m3/s.

Jan 1, 1979

By Hans Janzon, Ernst Buechi

INTRODUCTION The headrace tunnel in Amlach is part of a hydro electric power scheme near the city of Lienz in south west Austria. The project is owned and developed by Tiroler Wasserkraftwerke AG, the regional electrical supply utility. The construction work was divided into seven contracts for the entire scheme. The power output will be 60 MW, this being developed from a head of 370 m and water flows of 20 m3/s. The water will be tapped from the river Drau and lead through a 22 km long headrace on the south side of the Puster valley through the Lienzer Dolomiten mountain range. Contract No. 4, which is a joint venture between Mayreder, Züblin, Strabag, Rella and Innerebner, involves the construction of 13.5 km of the headrace. It was decided to bore this from one single adit, which probably makes it the longest pressure tunnel driven from one side by a TBM. (See Fig. 1.) For the tunnelling an Atlas Copco Jarva MK 12 TBM was chosen. The excavation diameter is 3.90 m, with the final lined diameter being in the range of 3.20 to 3.40 m. The back-up is a 145 m long single track rail system supplied by Mühlhäuser (Germany). Side-tipping cars with a capacity each of 8.2 m were used for removing the muck. One California switch was attached to the back-up after 3,000 m, and a second fixed switch was installed after 8,000 m of boring. 3 m long

Jan 1, 1987

By W. Haupt, M. Thormé, H. J. Ertle, K. Reim

Though Germany has a very old mining history, her experience in uranium mining only started in the late sixties. Today in the Federal Republic of Germany (FRG) there are only 5 small mines in the exploration stage, namely Menzenschwand and Müllenbach in the Black Forest and Mähring, Popenreuth and GroBschloppen in northern Bavaria. In all these exploration mines much development is required to define shape and size of ore bodies. Mining engineers, government authorities and environmentalists alike are very much concerned about environmental safeguards and protection of mine workers against radon and its daughter products. Miners are affected by internal and external radioactive exposure. In general the external [f3]- and [µ] -exposures can be considered as small in comparison to the internal exposure and are therefore not discussed in this paper. The internal exposure is caused by the inhalation of radon and its daughter products and is relevant to the lung as the critical organ. The nobelgas radon is inert and does not from compounds with other elements easily. Contrary to the physical half-life of 3,8 days the biological half-life of radon is only 10 to 20 minutes. During the rentention time in the body only approximately 1 % of the long-lived decay products are retained in the system (SCHOGER, 1976). In this connection is it important that the radon resorption as well as the radon secretion varies individually and depends to a large extent on the age of the person (SCHOGER, 1960). RENOUX et al. (1978) have determined that the greatest part of the a(-activity in the air is attached to aerosoles with a diameter of 0,4/14. The radiation exposure of the lung by radon is negligible if compared with the exposure by short-lived decay products. For this reason one has introduced the concept of the potential [o](-energy (P) of the short-lived radon decay products, which means the total [ct]-energy, which is produced when an atom decays in the decay-series down to the long-lived lead-210. [ ] The unity of the potential [o]-energy concentration in the SI-system is 1 j/m3 air. In radiation protection however a specific unit is used namely the working level (WL): [ ] The WL-unit, though internationally recognised has not been introduced officially in Germany. Because of the large amount of tunneling still to be done in the FRG, the various mines departments responsible for safety and health in mining ask searching questions such as: - What are the laws governing radon emanation in tunneling? - Can workers be adeguately protected against radiation hazards? - How should one drive through high grade uranium ore? - What happens if the ventilation system breaks down?

Jan 1, 1981

By Roshan B. Bhappu

The extraction of gemstones, except for diamonds, continues to be a more or less handpicking type operation all over the world. However, considering the physical properties of gemstones such as density (sp.gr.), color, size, shape, luster, brilliance, reflection of light and the like in contrast to the relatively ‘dull’ physical characterization of the associated gangue minerals, it should be feasible to recover several gemstones using modern mineral processing techniques. This paper illustrates the unique physical characterization of several gemstones and suggests appropriate mineral processing techniques that could be used to recover these precious stones. Special emphasis is placed on the versatility of the Heavy Media Separation (HMS) process for processing of the gemstones. Finally, a few examples of commercially viable operations involved in the recovery of emeralds and rubies are presented.

Jan 1, 2005

By J. M. Mutmansky, Y. J. Wang

The method usually used to predict the direction of flow in a connecting airway is to conduct a survey of the two existing nodes to be connected by the new pressure airway. It is then assumed that the air will flow from the node with the measured higher pressure to the node with measured lower pressure. This paper examines this direction-of-flow problem using properties of the system characteristic curve for a two-terminal network and specifies some conditions that will ensure that the air will flow in the direction anticipated. It was concluded that the only requirement is that all characteristic curves of the fans in the network should be strictly decreasing. Five numerical examples illustrate some important proper- ties of the direction-of-flow problem.

Jan 1, 2000

By B. K. Mishra, R. K. Rajamani

Discrete element is a numerical technique for describing the collision dynamics and motion of an assembly of particles. In particular, calculations are done on full three-dimensional space with a force-contact law for collisions and Newton’s law for subsequent motion. It may be said that there is no empiricism in this approach. The paper describes the full scale simulation of large diameter semiautogenous grinding mill of size 40X24 ft. It is shown that the simulation predicts the power draft of plant size mill extremely accurately. Also these simulations have been adapted uniquely to assess the motion of pebbles and slurry in pulp lifters. The passage of slurry from pulp lifters into trunnion is extremely important since flow-back and carryover must be avoided at all cost. The dynamics of slurry flow through pulp lifters is also described in this paper.

Jan 1, 2003

Simulator technology has advanced to the point where the cost of mining equipment simulators is beginning to make commercial sense. Simulator-based evaluation allows operators or potential employees to be assessed in a pseudo-real environment under surface and underground mining conditions. Simulator training also allows operators to be exposed to emergency and advanced situations such as brake or steering failure or a tireblowout. ThoroughTec, of South Africa, provides simulator equipment to the mining industry. The company’s various packages of simulator products provide an unbiased evaluation score that removes human error from the assessment process. This same evaluation score is also presented at the end of normal training or refresher training sessions. In this way, the simulator helps eliminate bad habits and improve efficiencies.

Jan 1, 2003

By Michael Beyer

Following the last Cholera Epidemic in 1872, resulting in approximately 400 deaths, the City Council of Munich decided to re¬place the former water supply system within the city limits by tapping new water supply areas outside of the city. Since 1883 Munich has been obtaining its water from the Mangfall River catchment located some 35 km to the south. Its most distinguishing characte¬ristics are as follows: 1) the water is free-flowing, i.e., a pumping system is not required as the catchment area is 100 m higher than the city; 2) the water does not normally have to be treated, meaning "spring fresh" tap water. On a daily basis, 300,000 m3 of water flow through the more than 100 year old pipes, accounting for 70% of the city's daily need. There was originally no requirement of a water tight system as strategically installed drain pipes prevented the build-up of exter¬nal water pressure on the lining. As the qua¬lity of today's water has become significant¬ly worse, the tunnels are now in dire need of restoration or replacement.

Jan 1, 1995

By Li. S. D., R. X. Zhang, K. M. Li, Y. D. Zhang, Y. J. Hou, S. G. Li

A computer aided design software system for long range coal surface mine planning has been developed by the authors. The system is composed of two subsystems: a coal deposite sub- system and a long range mine planning system. The geological parameters are estimated and a grid model is formed, then a 3-D block model can be developed for mining design. The long range surface mine planning system is based on oriented graph simulation and combined approaches to seek for the optimal deign alternative. This mining model consists of a number of sub-models to realize mining design functions such as: calculation of mining volume and coal quality by graph scanning; determination of operational stripping ratio by interactive design; varification of annual coal production; delimitation and development of dumping site; optimization of material flow direction and volumes by Linear Programming; surface mine production scheduling by interactive iteration; etc. The software package was developed on PC computer 486. It features classified menu guide, module structure, figure and graph representation on the screen and flexible interactive functions. This system has been applied to an open cut coal mine and predicted functions have been obtained.

Jan 1, 1996

By Bernard Lippe

The successful construction project is one in which the component construction operations are completed within the scheduled time and cost parameters. Most construction projects, however, are subject to delays and/or disruptions which adversely affect the time (start, duration, and completion) and cost aspects of the project. DELAYS Delays fall into two categories: Compensable Delays for which the contractor is entitled to contract time extensions and additional money as compensation for the extra expenses generated by the delay or obstruction to job progress, and Non Compensable Delays, for which the contractor may or may not receive an extension of time but no additional compensation. Compensable Delays Compensable delays may take the form of holds or suspensions on all or certain segments of a project by the owner, failure of the owner or his Engineers to approve shop drawings, cuts or material samples within a reasonable period of time, failure of the Owner or his Engineer to properly coordinate the job, discovery of design deficiencies in the plans and specifications which prevent the continuation of construction until

Jan 1, 1974

By T. Negeri, A. O. Orumwense

Microwave pretreatment is one of the emerging technologies which have been reported as having potential economic benefits for the processing of amenable ores. The application of microwave pretreatment to the processing of refractory and finely disseminated ores is of great interest as the technology can potentially reduce high comminution costs and improve mineral liberation. Sized ore samples were subjected to microwave irradiation at power levels varying from 1 to 5 kW over exposure times of between 1 and 6minutes in order to determine the influence of heating rate on mineral transformation, ground product size distribution and mineral liberation. The microwave irradiated samples were ground and subsequently floated. A comparison is made with non-microwave treated samples. Flotation grade and recovery show a strong dependence on the microwave absorption characteristics of the mineral components of the ore, in the following decreasing order -sphalerite, galena, and lastly chalcopyrite.

Jan 1, 2003

By Faruk Oksuz, Clay Haynes, Miguel Sanchez, Patrick Finn, Roger J. Maurer

The Milwaukee Metropolitan Sewerage District’s (MMSD)’s challenges of basement flooding and wet weather sewer overflows are being creatively addressed with the Northwest Side Relief Sewer tunnel. The $132 million, 20-foot diameter, and37,740 feet long conveyance and storage tunnel excavation in dolomite at depths reaching 165 feet below ground surface has been successfully completed within13 months in April 2004. This paper includes Owner’s perspective on the overall project, and the design and construction details by the Designer and the Contractor. The project contract documents included a comprehensive Geotechnical Data Report and the Geotechnical Baseline Report.

Jan 1, 2005

By Yiming Sun

The 5-mile long Bay Tunnel is a major water supply facility to be constructed under the San Francisco Bay and adjacent marshlands between the San Andreas Fault to the west and the Hayward Fault to the east. The tunnel will have a two-pass lining system consisting of a watertight precast concrete segmental initial lining and a welded steel pipe final lining. Considering the Bay Tunnel?s location between two major active faults, the design earthquake produces a significant peak ground acceleration estimated at approximately 0.6g. To develop a design that can achieve the seismic performance objectives, full dynamic seismic analyses were performed using site-specific earthquake time histories. The analyses considered soil-structure interaction and an evaluation of the transverse and longitudinal effects of the design earthquake. This paper describes the seismic analyses and the design measures recommended to minimize potential adverse effects of the design earthquake on the tunnel final lining.

Jan 1, 2008

By E. R. Drevdahl

It has been suggested that we at the University of Arizona present a paper covering the origin, philosophy, and results of the College of Mines program in the field of computers and operations research. I have worked with the program since its beginning, and I will try to outline the developments as they have taken place. The formal development of the educational and research program in the field of Operations Research and Computer Applications at the College of Mines, University of Arizona, began in early 1957. During the year, the University offered its first formal instruction in computer programming. This was my first introduction to computers, and it did not take long to realize that this new tool had a potential that could be profitably utilized by the mining industry. In March 6f 1957, the University Computing Center began operations with its IBM 650 computer. This machine was the only computer of this size in the local area at this time, The first programming effort was in machine language and the programming cost could only be justified for repetitive-type of problems. The progress in the computer field moved very rapidly and with the development of the many compiler and assembly programs and the addition of sub routines to the computer library, the scope of problems that could profitably be investigated by computers expanded rapidly.

Jan 1, 1963

By Tsuneyoshi Funazaki, Takayoshi Nakamura, Keizo Miki, Takashi Imaishi

The underground portion (about 10 km) of Tokyo Wan Aqua-Line consists of eight shield tunnels connected with Kawasaki Man-Made Island in between, at four underground locations. The connection work had to fulfill strict precision and safety requirements in the ground about 60 m below soft seabed, but was completed successfully in May 1997. This report describes the connection work in detail, featuring the method of investigating shield machines’ relative positions, ground freezing method and connection mechanism and procedures. It also mentions the present state of Tokyo Wan Aqua-Line that was put in service on December 18, 1997.

Jan 1, 1999

By Jody Kelso, Thomas R. Clark, Gregory J. Olson

Refractory, sulfidic gold ore from the Metates deposit in Mexico was tested to determine if it could be heap biooxidized to improve gold extraction. Small column tests were conducted in a manner consistent with anticipated process conditions: increased tempera­ture due to oxidation of the high sulfide content ofMetates ore and full recycle application of leach solutions containing high concen­trations of dissolved solids. Biooxidation by thermophilic (heat­loving) microorganisms was tested to determine: 1. the extent of sulfide oxidation and bottle roll precious metal recovery, 2. reagent consumption, and 3. potential solution flow problems due to mineral precipitation.

Jan 1, 1998

By N. B. Aughenbaugh

Compacted, fine-grained soils, often referred to collectively as clays, are used as permeability barriers in many mineral engineering projects such as heap leaching, containment ponds, tailings disposal and earth dams. Source materials for these liners include a variety of sand, silt and clay admixtures. These exhibit dramatically different engineering properties when densified. Therefore, it is imperative to adequately assess and characterize any soils being considered for compacted liners. The permeability and plastic properties of fine-grained soils are reviewed with respect to the state of compaction as the water content varies. Because they are weak in tension, compacted clays are susceptible to cracking when subjected to differential flexural movements. Designs of compacted clay liners also must include an evaluation of their flexibility. That is the ability of a fine-grain soil to bend plastically without cracking. This paper will also discuss the importance of flexibility with respect to soil types, compaction effort, failure mechanism and testing evaluation to the performance of clay liners in preventing seepage of pollutants from a containment site.

Jan 1, 1991

By K. H. Lee

The rate of beryllium dissolution from a low-grade ore was studied in sulfuric acid solutions. The effect of stirring speed, sulfuric acid concentration, particle size and temperature on the rate of dissolution of beryllium was established. The results of the study showed that the dissolution rate is independent of stirring speed within the range of 250-1000 rpm but depends on 1/2 power of the sulfuric acid concentration. The dissolution rate increases exponentially with decrease in particle size and the maximum attainable rate of extraction with respect to particle size is 6.6 x 10 mol dm min. The apparent activation energy (^E) for the dissolution reaction is 54.4 kJ/mol (13.0 kcal/mol). Based on this magnitude of the activation energy, it is concluded that a surface chemical reaction is the rate limiting step for the temperature range (70° -100°C) investigated.

Jan 1, 1988

By H. E. Epstein, B. K. Parekh, W. M. Goldberger

Comminution is the single most expensive operation in mineral processing. It consumes about 50% of the energy required for mineral extraction (Agar, 1976). Current comminution technology is both energy-intensive and inefficient. A novel noncontact comminution process concept was developed in this study, whereby selective lib¬eration of minerals from an ore could be potentially achieved. The process involves application of electric and ultrasonic energy to liberate minerals from gangue particles. Introduction The mineral industry is a large user of energy in the US. Energy usage is increasing as the grade of ores processed decreases. It is es¬timated that comminution of ores uses about 32 000 kWh (115 trillion kJ), or 2% of the electric power produced in the US (NMAB-365, 1981). Among other minerals, ce¬ment, iron, and copper processing plants are the largest users of en¬ergy in comminution. Very little of this energy used in conventional grinding (about 1%) is used to gen¬erate new surface. The remainder is wasted (Table 1). Thus, there are substantial energy-saving and economic incentives to improve the efficiency of crushing and grinding techniques for mineral recovery. With an energy efficiency of only 1%, it would seem possible to devise methods to significantly improve comminution technology. This requires that breakage force be applied only where needed, not indiscriminately as in a conven¬tional ball mill (NMAB-365, 1981). Can apparatus and methods be de¬ veloped for large-scale commer¬cial use that allow energy to be fo¬cused at intergranular bounda¬ries? If this can be done, mono¬mineral grains would remain in¬tact and the grinding action would be selective and substantially more efficient. The novel comminution process concept described in this paper uses a combination of electric and ultrasonic energy. This energy breaks the ore and selectively lib¬erates minerals. The process has also been termed a two-stage or electroacoustical comminution process (Goldberger, Epstein, and Parekh, 1982). The mineral grain boundary is usually the weakest area in an ore. By applying electri¬cal energy to the ore, the rock frac¬tures mostly at grain boundaries. At the same time, the electric shock creates secondary hairline fractures in the ore. Additional application of ultrasonic energy to this ore provides further break¬age. The concept was proven on a molybdenum porphyry ore but needs additional study. Technical Background There have been substantial im¬provements in milling machinery and grinding operations, but rela¬tively few attempts have been made to develop alternatives to conventional impact milling. Sev¬eral methods, however, have been investigated that relate to this study. In the early 1970s there was considerable interest in a size re¬duction method known as the Snyder Process (Cavanaugh, 1972). It involved charging coarse ore into a pressure chamber, pressur¬izing with a gas, and activating a quick-opening (15 msec ) dis¬charge valve that connected the chamber to a discharge duct. This allowed solids to fluidize and ac¬celerate, subjecting the material to a variety of impulse phenomena that caused the desired size reduction. Other nonimpact means of achieving breakage and selective size reduction have been de¬scribed in technical and patent literature. Kanellopoulos and Ball (1975) considered using heat to induce thermal stress in quartz¬ite. This would cause cracking and, thus, increase grinding efficiency. The use of electrical energy to induce thermal stress was studied by the General Elec¬tric Co., in cooperation with the Montana School of Mines, under a research grant from the Anaconda

Jan 9, 1984