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By G. W. Johnston

INTRODUCTION For many years mining at the Stobie mine of the Inco Metals Co. consisted mainly of fill-type mining for higher grade ores and block caving or blasthole open stope mining for lower grade ores. Open stope mining, although quite favorable in the initial stoping phase, has always presented problems in the pillar recovery phase, especially at depth. In 1966, sublevel caving was introduced. This method is ideally suited for low-grade ore and can be applied very successfully to intermediate or higher grade ores providing proper controls are enforced. Sublevel caving has three distinct advantages: it is highly adaptable to mechanization; it recovers the ore in one operation; and it provides adequate ground sup¬port and safety regardless of mining depth. This method does, however, make extra demands, particularly for new types of supporting services. The constant presence of rock makes quality control of the grade of the ore being extracted essential. Increased de¬velopment, different types of ventilation, roadways, and maintenance are only a few of the many changes re¬quired. The care and maintenance of the fleets of diesel equipment and the modification of equipment is a con¬stant challenge. CHOICE OF SUBLEVEL CAVING The question arises, why mine by sublevel caving? Fig. 1 shows a typical problem encountered by the open stope or blasthole mining method. Near the surface there is little or no ground support problem. As mining progresses to an intermediate depth, however, ground failure starts to occur in the supporting pillars. If open mining is carried beyond this point, the critical depth is soon reached, accompanied by hanging wall caving, ex¬tensive pillar failure, and the danger of losing control of the mining cycle. The rock caved from the hanging wall mixes with and dilutes the ore being extracted from the blasthole stopes. Ore losses occur when pillar failure pre¬vents drilling and development of part of the ore. The interruption to the mining cycle causes serious curtail¬ment in production until ground failure is controlled and the mining method changed to adapt to the new conditions. Having recognized the limitations of open stope min¬ing, alternatives were sought. The first alternative (Fig. 2) was to fill the open stopes with sand fill be¬fore extensive pillar deterioration occurred, recover the pillar ore by fill mining, and then convert to total fill mining below. If the ore grade is high enough it can support the costly fill method. Recovery will be at a much slower rate and will therefore extend over a longer period of time. On the other hand, sublevel caving gives complete primary mining recovery in a short time and is very adaptable to mechanization, which is now a necessity to combat spiralling labor costs and give greater produc¬tivity per man. Sublevel caving is ideally suited as a mining method for low-grade ore bodies which eventually reach a criti¬cal depth for open stope mining. DEVELOPMENT The development phase comes first and of course its main purpose is to gain access to the ore and provide a route for ore removal from the mine. Initially a 20% inclined service ramp is driven in the footwall rock (Figs. 3, 4, and 5). It is preferable to start at the top of a mining block and drive the ramp down¬ grade so gravity can assist in mucking the blasted de¬velopment round, and also access can be gained more quickly to the initial production area. The ramp nor¬mally turns at 3.1 rad (180°) about every 152.4 m (500 ft) to keep it reasonably close to the rock disposal

Jan 1, 1982

By Madan M. Singh

With the current emphasis on ecology, safety, and conservation of natural resources, some consideration should be given to methods of mining that reduce surface damage, make the mining of coal less hazardous, and allow exploitation of a larger percentage of the coal in situ. One method that can be helpful toward attaining these objectives is the use of packing or stowing. Stowing involves the replacement of the ore that has been removed by waste material obtained from within the mine or elsewhere. Evidently, it would be most beneficial if this waste for packing were available from the mine being worked, but generally this is not possible. If complete stowing is adopted, it is necessary to bring in packing material from other sources. Stowing tends to reduce surface subsidence, but not eliminate it. It enhances roof support and curtails accumulation of methane in the gob, making the mining operations safer. It may also allow one to obtain a larger amount of coal. Currently, in the United States, a substantial amount of coal is left in place as pillars, in the hope that it will support the overburden indefinitely. Some of these could be extracted with stowing. The mining of thick, steep, or contiguous seams would also be facilitated.

Jan 1, 1974

By T. G. Rozgonyi

The basic goal of this investigation was to determine the degree of drying of high moisture lignite through the use of high temperature and pressure steam autoclaves. Specific items studied were: a) the effect of lignite particle size, b) steam temperature and pressure required, and c) the time of ahydration. Although removal of sodium, ash, sulfur and other ash-forming minerals was not the goal of this study, basic analysis of effluent water showed organic material and alkalai metal content. Removal of inherent moisture from run-of-mine lignite was tested by lock-feeding the lignite, which was previously sized by screening into 25 kg autoclaves. High pressure, up to 4.053 MPa (588 psi), saturated steam was then introduced into the pressure reactor. Reaction time, pressure, temperature, and depressurization rates were strictly controlled for each reactor test run. Results indicate that about 80% of lignite total moisture was removed, including some of the inherent moisture, yielding a non-oxidized, and thus stable, lignite product. As stated, a side benefit occurred as some reduction of non-combustible portions of the lignite also took place. The conclusion reached as a result of the tests is that the steam-drying process can be successfully applied to reducing moisture in lignite, and may be considered for additional studies on acceleration of the coalification process. On the basis of the data presented, the author believes that lignite can be economically upgraded in steam autoclaves by simultaneously reducing the moisture content by 80 percent and the sulfur content by at least 50 percent. Upgrading the lignite by this method will result in large energy and financial savings.

Jan 1, 1984

By Todd Hollingsworth

The Boddington gold mine is located near Perth in Western Australia in the Saddleback Greenstone Belt, a fault-bounded sliver of Archaean volcanic and shallow level intrusive rocks, surrounded by granitic and gneissic rocks. The mine began operations in 1987, producing about 7.7 t/a (250,000 oz/year) until mining ceased in 2001. Built on the footprint of the original mine, the Boddington gold mine expansion project involved opencut mining from two large pits. Expected gold production is around 31 t/a (1 million oz/year) for the first five years. It will be the largest gold mine in Australia. The mine has proven and probable reserves of more than 622 kt (20 million oz) of gold and has an expected life of more than 24 years. The mine is currently solely owned by Newmont Gold Corp., the world?s second-largest gold mining company, employing around 28,000 people worldwide. The conveyor and belt feeder contract for the Boddington gold mine expansion project was awarded by Aker Kvaerner Clough Murray Roberts (AKCMR) to FLSmidth Conveyor Engineering Inc. in August 2006. The contract involved the design and manufacture of 15 conveyors and 17 belt feeders with belt widths ranging from 450 mm to 2.4 m (18 in. to 96 in.) and conveyor lengths from 16 m to 2,172 m (52 ft to 7,125 ft). The total motor power added up to more than 16,700 kW (22,400 hp). The total length of all belting was almost 11.5 km (7.1 miles), and the total fabricated steel weight was approximately 3.7 kt (4,100 st).

Jan 1, 2010

By Richard L. Sanford

The generalized rail haulage simulator described in this paper is an outgrowth of the need to expand a previously developed single level simulator to permit analysis of production problems where intermediate car storage is used. Many of the ideas of the former single level simulator, which is an integral part of an Underground Generalized Materials Handling Simulator (UGMHS), have been used in model development. In addition, experience gained in applying the earlier model to a variety of operating conditions has been heavily relied on. The generalized rail haulage simulation model can operate as an independent system and, as such, can be used to analyze rail haulage systems using production distributions as data input. In addition, this model is designed to replace the present rail haulage sub-assembly in the UGMHS model and the linking procedure has been integrated into the model. The flow of coal from production sections in UGMHS, for example, fill the mine cars and a condition of no empty cars at a loading station will shut down in by production systems.

Jan 1, 1974

Ferric (Fe3+) ions are omnipresent in flotation circuits. Depending on pH and the nature of the ore body, Fe3+ ions may play a role in the adsorption of thiol collectors on sulfide minerals. To investigate this possibility, a two-compartment galvanic coupling cell was designed. This cell was used to monitor changes in contact angle of a sulfide mineral in one compartment, while varying concentrations of the Fe3+ ions in the other. The results showed that Fe3+ ions promote xanthate adsorption as indicated by the increase in contact angle. Implications of this finding in sulfide mineral flotation in general will be discussed.

Jan 1, 1998

By Warren D. Stanford Stanford

Introduction The Sleeper mine is a near-surface gold mine located in a remote area 56 km (35 air miles) northwest of Winnemucca, NV (Fig. 1). The deposit was discovered in 1984 by an Amax exploration geologist. Favorable drilling results led to feasibility studies and metallurgical testwork. Final evaluation of the mine potential proceeded very quickly. The project received Amax board approval in July 1985. Eight months later, the process plant was fully operational. The first gold ($1 million) was shipped one month later, in March 1986. Total plant capital was $27 million. Payback was achieved in six months. The Sleeper mine was expected to produce 1.6 t (53,000 oz) of gold and 1.3 t (41,000 oz) of silver annually. However, the ore body exceeded all expectations. Production for the first 10 months of operation amounted to 4 t (128,000 oz) of gold and 2.9 t (94,000 oz) of silver. Direct cash operating costs are in the $1.77/g ($55 per oz) range. Amax is actively conducting exploration nearby for additional reserves to extend the mine's life. (See update on page 242.) Geology The Sleeper gold deposit is located on the northwestern flank of the Slumbering Hills and in the Awakening Mining District. Rocks exposed in the vicinity of the deposit are interbedded siltstones, sandstones, and limestones of Triassic age. They are overlain by latite lava flows and tuffs of Tertiary age. Dikes and sills of latite and andesite intrude the sedimentary rocks. Quaternary deposits of mostly sand with minor gravel and clay cover a pediment containing the gold deposit. The sedimentary and volcanic rock units have been transsected and offset by extensive north- northeast trending faults and less abundant northwest trending faults. Both fault systems fractured and prepared the ground for subsequent invasions of mineral-bearing hot spring geothermal waters. The hot spring systems produced widespread hydrothermal alteration and gold mineralization at silicified centers near feeder fault structures. The deposit is hosted by siltstone and latite that have been hydrothermally brecciated. The main breccia is elongated north-northeasterly. The hydrothermal breccia zones appear to dip steeply to the west. Gold mineralization consists of native gold and electrum deposited in two or more high-grade quartz-breccia veins. Lower grade gold mineralization occurs

Jan 4, 1987

By M. Board, C. Alexander, M. Ramström, W. Johnson

"Hecla - Lucky Friday is an underground mine that has been in operation for 75 years and produces from depths over 2.3 kilometers (7,500 ft) below the surface. Technical issues at this depth include high rock temperature and seismicity. The use of new innovative mechanization is being examined for ore production. Principal advantages of mechanization are the reduced exposure of personnel, reduced seismic triggers, and increased efficiency. Lucky Friday has partnered with Atlas Copco to design, build, test, and deploy a mechanical miner for primary ore production. We will discuss the background, concept, development and deployment strategy for a mechanical miner. BACKGROUND The Coeur d’Alene mining district in northern Idaho was first discovered over 130 years ago and has been the most prolific silver producer in the US. The Lucky Friday mine of Hecla Mining Company (Figure 1) is the oldest (76 years) and deepest mine in the district, producing approximately 725 tonne per day (800 tons per day) from narrow, vertical lead-zinc-silver veins. Cut and fill stoping is currently employed at depths to about 2.3 km (7,500 ft) below ground surface, making it one of the three deepest mines in the western hemisphere. The #4 Shaft, a winze collared at approximately 1.8 km (5,900 ft) below surface and extending to a depth of nearly 2.9 km (9,600 ft), was recently completed to exploit the high-grade 30 Vein, whose resource has been identified to at least 3 km (9,700 ft) in depth.As with other deep mines worldwide, a number of challenging engineering issues occur, including: high in situ rock stress, squeezing ground, seismicity, high in situ rock temperature that requires refrigeration, diesel equipment that generates diesel particulate matter (DPM) requiring high ventilation airflow rates, and long travel times for worker transport to mining areas."

Jan 1, 2018

By Donna Wallace

Past EPA groundwater monitoring programs required that contamination not leave the boundaries of a disposal facility. New regulations under the Resource Conservation and Recovery Act (RCRA) require that once hazardous waste constituents are detected beyond the limits of the disposal area, a program to define the rate and extent of contaminant migration must be instituted. Future regulations are likely to include even more stringent groundwater protection criteria. The implications of both the existing and probable future groundwater protection and monitoring requirements in terms of using geologic containment as a means of disposing of hazardous waste are explored in this paper.

Jan 1, 1981

By Paul C. Lingo

Two recent antitrust cases, coming from widely separated areas, different industries and involving wholly different facts were decided by the Supreme Court on June 7, 1965. The decisions in there two cases may well prove to be the most important and far-reaching decisions in the field of labor law that have been handed down in the last 24 years. These cases, although quite dissimilar factually, had one common element. In both, the gravamen of the antitrust violation was bottomed on the terms of labor agreements negotiated by a multiemployer group. These cases are usually referred to as Pennington1 and Jewel Teat. Since a number of references will be made to the antitrust laws, it may be well to state briefly the applicable portions. Section 1 of the Sherman Antitrust Act makes "every contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce among the several states, or with foreign nations, is declared to be illegal...". Section 2 imposes criminal sanctions against "Every person who shall monopolize, or attempt to monopolize, or combine or conspire with any other person or persons, to monopolize any part of the trade or commerce among the several states...". Under Section 4 of the Clayton Act a person who sustains damages as a result of a violation of the anti¬trust laws is entitled to recover treble damages plus costs.

Jan 1, 1966

By Robert L. Frantz

The various facets of university-company cooperative activities and the opportunities for collaborative research for the mineral industries are presented in this paper. The advantages and disadvantages of various alternative research funding arrangements for the researcher, the university, and the sponsoring corporation are discussed. Examples of university-industry cooperative research programs are briefly outlined. The concept of a cooperative mining research program is presented. The improvement of performance through techno- logical developments and human skills may well be the greatest competitive edge available to the U.S. mining industry. In this regard, the need for new endeavors between industry and universities can hardly be overemphasized.

Jan 1, 1984

By K. A. Natarajan, S. Usha Padukone

"An industrial waste liquor having high sulfate concentrations was subjected to biological treatment using the sulfate-reducing bacteria (SRB) Desulfovibrio desulfuricans. Toxicity levels of different sulfate, cobalt and nickel concentrations toward growth of the SRB with respect to biological sulfate reduction kinetics was initially established. Optimum sulfate concentration to promote SRB growth amounted to 0.8 - 1 g/L. The strain of D. desulfuricans used in this study initially tolerated up to 4 -5 g/L of sulfate or 50 mg/L of cobalt and nickel, while its tolerance could be further enhanced through adaptation by serial subculturing in the presence of increasing concentrations of sulfate, cobalt and nickel. From the waste liquor, more than 70% of sulfate and 95% of cobalt and nickel could be precipitated as sulfides, using a preadapted strain of D. desulfuricans. Probable mechanisms involving biological sulfide precipitation and metal adsorption onto precipitates and bacterial cells are discussed.IntroductionIndustrial effluents from hydrometallurgical and mineral processing operations often contain high sulfate and metal concentrations posing significant disposal problems, which require urgent solution to avoid serious environmental contamination. In such waste liquors, sulfate and heavy metals such as cobalt, nickel, zinc and iron originate from the chemical or biological oxidation of exposed sulfide minerals. Reduction of sulfate and precipitation of toxic metal ions from industrial wastes is essential from the viewpoint of environmentally acceptable waste disposal and recovery of associated strategic metals.Many of these heavy metals are essential for metabolic activity of bacterial cells at low levels. But they exert toxic effects at concentrations encountered in polluted water. Removal of toxic metals through biological reduction of sulfates from industrial waste waters have been practiced for several decades. Metal remediation through common physicochemical techniques such as oxidation-reduction, chemical precipitation, filtration, electrochemical treatment, evaporation, ion exchange and reverse osmosis processes is expensive and not suitable in the case of voluminous effluents containing complexing organic matter and low metal concentrations. Further, strong and contaminating reagents are used for desorption, resulting in toxic sludge and secondary environmental pollution. Biotechnological approaches can be more efficient and cost effective for detoxification of such effluents. Biotreatment/ bioremoval offers several advantages over conventional chemical and physical treatment technologies, especially for diluted and mixed contaminants. Biological detoxification, which involves the use of microbes to detoxify and degrade environmental contaminants, has received increasing attention in recent years (Iwamoto and Nasu, 2001). In addition, valuable metals can be recovered from metal sulfide sludge (Boonstra et al., 1999)."

Jan 1, 2015

By T. D. Arnold

The Barrick Bullfrog underground mine was established as an afterthought to the main open pit. As open pit ore dwindles, the underground mining becomes increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines, and there is a strong move towards underground mining in the United States today. There are inherent problems in starting and operating underground mines in the shadow of any open pit operation, and at the Bullfrog there were several attempts at productive increases that were both successful and unsuccessful.

Jan 1, 1996

By A. E. Isaacson

The U.S. Bureau of Mines is investigating a systems approach to metals recovery from leach liquors produced by in situ leach mining techniques. A successful in situ leaching process requires a thorough under-standing of the complex interrelationships that exist between leaching chemistry and metals recovery. Laboratory research is addressing these interrelationships in the solution mining of a copper oxide deposit. Laboratory tests have been conducted to gather baseline data related to the design and operation of continuous leaching-solvent extraction-electrowinning circuits. This paper addresses the findings of the baseline studies. Specific results include the characterization of simulated in situ leach liquors produced by leaching chrysocolla and chrysocolla-atacamite-bearing copper ores. Metal recovery procedures, utilizing four commercial solvent extraction reagents, are also characterized, and potentially troublesome leach liquor contaminants that may complicate waste management procedures are identified.

Jan 1, 1990

By C. A. Rowland

With the rapidly rising cost for electrical energy and the long range pre¬dictions for continued rising costs and even possible energy shortages, operation of rod, ball, autogenous and partial autogenous grinding circuits to efficiently utilize the power delivered to the mills will be demanded. This calls for a method to evaluate grinding circuit performance that is accurate, reliable and readily usable as an operating tool by supervisory, technical and operating personnel. Neither the Rittinger and Kick theories of comminution,(1) which preceded the Bond Theory by more than 50 years, had a mathematical means that could be used to predict and evaluate the performance of crushers and grinding mills used to comminute ores and rocks. This severly limited the practical use of these two theories, which were contradictory to each other. They have been superseded by the Bond Third Theory of Commnution.(1)

Jan 1, 1976

By S. A. Suhler

The detection of hazardous geological anomalies through remote sensing techniques is the subject of current research efforts sponsored by the U.S. Bureau of Mines. In this review, hazardous geological anomalies are discussed with respect to the "view" presented along with potential operational concepts for each technique. The design and development of a borehole radar is described with emphasis on the potential range and resolution capability of the system under realistic underground conditions. Results of field tests at two coal mines and at a hard rock future subway location are presented.

Jan 1, 1978

By W. A. Haley

As far back as 1939 state laws have required reclamation of mined lands. Reclamation has been the topic of many discussions and presentations, especially since the late 1960's. In the past ten years many states have added legislation concerning the reclamation of coal-mined lands. In the near future, it seems certain that some federal regulations will be passed that will set minimum guidelines for the states to regulate. Besides the requirement of returning the land to the approximate original contour, future regulations will more than likely demand replacing topsoil from one to five feet thick. As regulations become more stringent, costs will rise accordingly. Since no one has developed a machine that can do all reclamation work by itself, it is necessary to review in detail the tools available and to select the most economical means.

Jan 1, 1976

By Paul F. Ph. D. Ziemkiewicz, Courtney D. Black

According to the American Coal Ash Association, 105 million tons of coal combustion products (CCP) were produced by the power generating utilities in 1997. Of that total, 1.68 million tons were used in mining applications (ACAA, 1997). Results have ranged from the environmentally beneficial to neutral and, in some cases, detrimental. Twenty years ago coal ashes: bottom and fly ashes constituted nearly all CCPs. With the shift to new emission control technologies at power plants, however, large volumes of new products are being generated. Many do not lend themselves to traditional ash applications such as cement formulation. Many CCP disposal sites are not documented with reliable pre and post application monitoring. In this report we discuss types of CCP, their relevant characteristics and the mining environment. We have attempted to identify a range of documented applications and to draw conclusions about their environmental effects including benefits and adverse impacts.

Jan 1, 2000

By R. A. Haney

The Mine Safety and Health Administration (MSHA) has conducted studies both in coal and noncoal mines to evaluate methods for sampling and separating diesel particulates from mineral dust aerosols. The agency is investigating size separation techniques to distinguish between diesel particulate and respirable coal mine dust. Additionally, ashing techniques have been used to distinguish diesel particulate from mineral dust in metal and nonmetal mines. As part of these studies, personal exposures to diesel particulate for various mining occupations have been measured. This paper describes the measurement techniques and summarizes the exposure levels for various underground mining operations.

Jan 1, 1990

By Aurel Goodwin

I chose the title "Let's Clear the Air" for this afternoon's presentation because it has two meanings, the literal and the figurative. Most of you know what MSHA is. Most of you know what MSHA does. And, for the most part, most of you know why. What I hope to accomplish today is to "clear the air" around our health standards, to clarify for you how MSHA views its congressional mandate under Title I Section 101(a)(6), (7), and (9) of the Mine Safety and Health Act. Asbestos, silica, radiation, noise, welding fumes, carbon monoxide, lead, hydrogen sulfide, nitrogen dioxide - the list of physical and chemical hazards encountered in the metal and nonmetal mining industry is as diversified as the industry itself, possibly even more so. In addition, miners are often exposed to several of these health hazards simultaneously.

Jan 1, 1980