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By Wu Xueling

9K medium was used to isolate iron-oxidizing bacteria from 27 sump water samples collected from Dexing Cop-per Mine, Chengmen Mountain Mine and Yin Mountain Mine, Jiangxi Province, China. Lead acetate and silver nitrate were used to enrich metal-resistant iron-oxidizing bacteria from the above water samples. Isolate 16 was isolated from the sample taken at Dexing Copper Mine. Growth experiments indicated that when incubated under lead acetate (3,500 mg/L), isolate 16 still carried out ferrous ion oxidation, while isolate H1, a less resistant strain taken at Yin Mountain Mine, had a tolerance level of only 400 mg/L. When assayed with other metals, i.e., Ag+ (240 mg/L), Hg2+ (0.9 mg/L), Cu2+ (32,000 mg/L) and Mg2+ (22,500 mg/L), isolate 16 still carried out ferrous ion oxidation while, on the other hand, isolate H1 exhibited much lower tolerance levels, i.e., Ag+ (60 mg/L), Hg2+ (0.1 mg/L), Cu2+ (19,000 mg/L) and Mg2+ (13,500 mg/L). Based on 16S rDNA sequence data, isolate 16 and H1 were both identified as Acidithiobacillus ferrooxidans.

Jan 1, 2007

In June, 1,334 underground construction and tunneling professionals gathered in Toronto, Ontario for the 2007 Rapid Excavation and Tunneling Conference (RETC). This biennial event, sponsored by SME, is one of the global underground construction industry?s major events. And this year?s RETC was the first one that included the new Underground Construction Association. [ ] (UCA) of SME. In addition, the conference?s exhibit attracted 125 equipment and service providers. The next Rapid Excavation and Tunneling Conference is set for June 14-17, 2009 at Caesar?s Palace, Las Vegas, NV.

Jan 1, 2007

By R. D. Peterson

As underground mine operations expand, the ventilation systems supporting them become complex. Complexity increases with periodic ventilation changes. New diagonal connections require a rebalance of resistance to maintain airflow in affected splits in the system. Incidents of mine fires and explosions have occurred in U.S. coal mines when diagonal connections resulting from ventilation changes have resulted in changing airflow directions. MSHA regulations prohibit the reversal of airflow and poor ventilation practice in general, but regulations cannot stipulate or recommend proactive preventative measures because every situation is different. This paper discusses the phenomenon of diagonal branches and recommends practical precautionary measures that can be taken to prevent airflow reversal in planned ventilation changes.

Jan 1, 2012

By Simon D. Strauss

This article is part of a presentation Strauss made Dec. 3, 1988 at the sixth annual American Mining Hall of Fame (AMHofF) banquet in Tucson, AZ. At the banquet, the Mining Club of the Southwest honored Strauss by naming him the 1988 recipient to the AMHofF. (Industry newswatch, page 6). Introduction In the last two decades, there have been two previous periods of sharply rising copper prices. One was in 1973-74; the other in 1979-80. In both cases, a short period of high copper prices was followed by steep and prolonged periods of low prices. In the language of the market analyst, the high prices were called spikes. Is it likely, then, that three or four years from now the present price of copper will show up as a spike in the charts? There are substantial differences between the current position and the markets of 1973-74 and 1979-80. In 1973-74, US copper prices were subject to government-imposed price ceilings of $0.60 per lb through early December, 1973. These were increased to $0.68 per lb through May, 1974. Meanwhile, mines outside the United States were free of restraint. Rising demand in London pushed the price above $1 per lb in the third quarter of 1973. In early April 1974, it reached a peak of $1.50 a lb. In May of that year, the US ceilings were removed and the domestic price began to rise. What were the causes of this price strength? While ceilings held the domestic price below the world market, domestic consumers acquired all the tonnage offered by US mines. Meanwhile, in the world market, buyers feared prolonged shortages. The Club of Rome had warned that world economic growth would be limited by impending depletion of mineral resources. There was al so concern about a copper cartel that might increase copper prices even more. In early 1974, at a special United Nations session, developing-country spokesmen warned the industrialized world to expect high commodity prices. Also adding to the concerns of copper buyers was the fear that when US wage contracts expired in mid-1974, protracted strikes might ensue. The combined effect of this atmosphere was that consumers accumulated large amounts of copper, far above their normal carry. By midsummer, the position changed radically. While some strikes did occur in the United States, they proved short-lived. The most significant development was a massive economic recession. The energy crisis was causing enormous dislocations in the world economy. Construction activities were sharply reduced and automobile sales plummeted. Public confidence was shaken. Copper sales fell precipitately as consumers decided to draw down their swollen inventories. The price came down too. In April 1974, the London price- as noted-was $1.50 per lb. By the end of the year, it was down to $0.57 per lb. In 1973-74, the copper price rise was fed by fears of shortages, cartels, and strikes. In 1979-80, the market rose on the strength of good demand plus political and military instability. The price rise was also fed by inflationary trends, exemplified by speculation in precious metals. Prior to this second spike in copper prices, the market had been depressed despite economic recovery. Despite reduced US output, copper production in the rest of the world was increasing. Though consumption was rising, surplus stocks reached unprecedented levels. At the end of 1977, the aggregate of stocks at the refineries and in the exchange warehouses was 1.5 Mt (1.67 million st). That was more than three months' shipments at then rates of consumption. In 1978, the statistical position improved. Shipments of refined copper that year were 8% greater than in 1977. The result was reduced visible stocks but -just as was to be the case in 1984-86 - the price remained depressed. In 1979, an even sharper drop in visible stocks occurred as shipments rose by another 4%. This time, though, the price responded. In December 1978, the price in current dollars had been less than $0.70 per lb. By the end of 1979, it was above $1 per lb. And in the first quarter of 1980, it averaged more than $1.20 per lb. Military and political developments were a factor. The hostage crisis in Iran was followed by the Soviet invasion of Afghanistan. To many, it appeared that war might result if the Soviets pushed on into Pakistan. At the same time, speculation drove gold and silver prices to incredible levels. As silver prices rose above $40 per oz), copper above $1 per lb did not seem unreasonable. Then, in March 1980, the precious metals price boom collapsed. Copper prices also retreated, though not as much. In February 1980, the copperprice averaged $1.32 per lb. By December, it had dropped to $0.85 per lb. In 1981 and 1982, the decline continued. The present copper situation Why is the current situation different from these two previous episodes of high prices? First of all, today's inventories are far lower than they were in either 1974 or 1980, when the price declines began. The stocks at refineries and in exchange warehouses are substantially less than they were then. More significantly, consumers today have very limited holdings compared with stocks they carried in 1974 and 1980. Even if faced with a downturn in their own business, copper consumers will not be able to stay out of the market. To the extent they have any business at all, they will have to buy copper. And on the supply side, there is also a significant difference. The year 1988 has been unusual. US production is up sharply, responding to higher prices. But production is little changed in the rest of the Free World. Indeed, several of the major producing countries have mined less copper this year than in 1987 despite the prices increases. Peru has had labor problems that have cut its output. Zambia and Zaire suffer from shortages of expatriate technicians, not to mention spare parts. They also suffer from the failure to maintain equipment or perform adequate development. In Chile, the two largest mines, Chuquicamata and El Teniente, have not met their production targets. Chuquicamata is struggling with high arsenic content in its ore. And, in late 1987, severe rockbursts hampered operations at El Teniente. In addition, depletion of some mines in Australia and South Africa has offset rising output at other properties. Indeed, when final mine output figures for 1988 become available, it may well be

Jan 1, 1989

By Robert D. Coyle, David L. Emmons

Introduction The Cove gold-silver deposit is located in Lander County, NV about 50 km (30 miles) southwest of Battle Mountain, NV (Fig. 1). The deposit is in the north-central part of the Fish Creek Mountains within the McCoy mining district. Gold was first discovered in the McCoy district in 1914 by Joseph H. McCoy (Vanderburg, 1939). From 1928 to the early 1930s, minor production occurred from shallow underground workings. Total gold production was less than 311 kg (10,000 oz; Stager, 1977). The district was inactive until the mid-1960s when it was explored by Bear Creek Mining, Summa Corp., Houston Oil and Minerals Corp., Gold Fields, and Tenneco Minerals. Tenneco began a detailed reevaluation of the McCoy deposit in the fall of 1984. Tenneco's decision to place the deposit into production was based on a geological reserve of 8.7 t (280,000 oz) of gold (Kuyper, 1987). Subsequent exploration and development drilling of the McCoy skarn deposit has more than doubled the mineable skarn reserves to 19 t (615,000 oz) of gold. In September 1985, Tenneco began development work on the McCoy gold-skarn deposit. The project is an open-pit, heap leach mine. The first gold was poured in April 1986. Echo Bay Mines acquired Tenneco's precious metals properties in October 1986. The mining operation and district exploration started by Tenneco is continuing under the Echo Bay's ownership. The Cove deposit was discovered in January 1987 and production began in February 1988. The deposit will begin as an open-pit, heap leach operation. It will be converted into an open-pit and underground mine with a 9-kt (10,000-stpd) mill. Geologic setting The Cove gold-silver deposit is situated on the east flank of the Fish Creek Range. Surface elevations range from 1460 to 1680 m (4800 to 5500 ft). The deposit is 1.6 km (1 mile) northeast of the McCoy gold-skarn deposit. The Cove deposit is hosted by the Augusta Sequence of Triassic age. Three formations of the sequence are mineralized at the Cove. In ascending order they are the Favret, Panther Canyon, and Augusta Mountain formations. The Favret formation is a gray, locally silty limestone that is commonly fossiliferous. The base of the formation is not exposed. Exposed and drilled intervals are more than 60 m (200 ft) thick. Conformably overlying the Favret formation is the Panther Canyon formation. This formation is 215 m (700 ft) thick and consists of a siliclastic and carbonate sequence of conglomerate, quartzite (sandstone), mudstone, limestone, and dolomite. It is a distinctly coarsening-upward sequence of rocks. The top of the unit is conglomerate with chert and quartzite clasts up to 150 mm-diam (6 in.-diam). The Augusta Mountain forma-

Jan 8, 1988

By T. Payne

Underground heat issues are mainly focused on the detrimental effects to a workers health. However, working in hot, humid conditions has other negative effects. Studies have shown that safety, productivity, workforce morale and operating cost are also worsened in these conditions. The human body has several mechanisms for rejecting heat and remaining cool. However, once the air temperature exceeds about 34°C, the only effective mechanism is by evaporation of sweat from the skin. This is assisted by acclimatisation which is the human body?s enhanced ability to combat extended exposure to heat. The body has to remain well hydrated when working in heat as even small degrees of dehydration cause significant decreases in the ability to work in heat. There are two ways in which heat load can be reduced: Through use of refrigeration/vent/cooling to reduce thermal stress on workers; Reduce the contribution that heat sources have to underground heat load (e.g. reduce idle time, fleet size, etc). Some of the sources of underground heat have the potential to be more manageable than others. Geothermal heat and heat from autocompression will be found in all mining situations in varying degrees depending on geothermal gradient and surface temperature, however, the use of equipment and blasting may be streamlined to reduce the underground heat load. It is through a combination of the available options that most mines will successfully control their heat related problems. Mt Isa, which has been a focus for heat related study in Australia, has successfully implemented protocols for working in heat. Through combining these with the installation of a surface bulk air cooling plant, Mt Isa has consistently reduced the incidence of heat illness. This is likely to be the most cost effective method of reducing heat load for deep mines in Australia. Shallower mines which may only occasionally encounter hot conditions should consider more portable cooling options. This study will review the heat issues in underground Australian metalliferous mines.

Jan 1, 2009

By E. Rubenstein, V. Gangrade, K. V. Raj, M. L. Harris

Underground stone mine ventilation is characterized by large openings with low resistances. These mines primarily face three challenges: moving adequate volumes of air, controlling and directing the airflow, and planning ventilation systems that work well with production requirements. Given these challenges, this paper examines the data collected by the Mine Safety and Health Administration (MSHA) to determine the extent to which respirable crystalline silica (RCS) and diesel particulate matter (DPM) are an issue in underground stone mines. Out of 522 sampled mines, there were 108 personal samples exceeding the RCS Permissible Exposure Limit (PEL) during 2000–2020. DPM were more prevalent than RCS in these mines with 382 personal samples exceeding the DPM PEL out of the 929 mines sampled during 2002–2020. Dilution of DPM is usually the defining parameter for design of mine ventilation systems in largeopening underground stone mines. With this knowledge, focused attention can be directed to these mines so that appropriate prevention and mitigation techniques can be utilized to prevent stone miners’ exposure to RCS and DPM and subsequent respiratory diseases.

Mar 2, 2022

Soil erosion is strongly related to soil hydraulic properties. Understanding how surface coal mining impacts those properties is important in developing effective management practices to control erosion during reclamation. Soils from undisturbed areas, roughly graded mine spoil, replaced topsoil before seeding, and revegetated areas at the Rosebud Mine in Eastern Montana were evaluated to determine impacts on soil hydraulic properties. Field and laboratory studies were conducted to determine soil hydraulic properties, including particle-size distribution, organic matter content, and saturated hydraulic conductivity. WEPP simulations and risk analyses were performed on the soil hydraulic property data to determine the impacts of changes on soil erosion. The hydraulic properties of the soils in each representative area have significant differences due to the mining and reclamation practices at the mine. WEPP simulations show that the potential for soil erosion increases due to mining activities disturbing the soil. WEPP simulations also indicate that the potential for erosion may return to pre-mining levels over time with effective revegetation practices.

Feb 27, 2013

By D. Tao, R. Honakey, B. K. Parekh

The dewatering of stable phosphatic clay suspensions generated from phosphate beneficiation in the central Florida is an issue of practical and theoretical importance. Because of its tiny particle size and surface charge, the phosphatic clay takes up to 20-30 years to settle in water and causes environmental, aesthetic, economic, and handling problems. An efficient and cost-effective dewatering/consolidation process for phosphatic clay is of great interest to the phosphate industry in Florida. In this paper, the consolidation and dewatering behavior of phosphatic clay was studied by use of anionic flocculants with and without sand addition. The effects of pH, initial polymer concentration, polymer dosage, polymer addition steps, and metal cations (K+, Ca2+, and Al3+) on the flocculation of phosphatic clay have been studied. Experimental results indicated that clay suspensions were well flocculated at pH 10.5 by DPW-1-1355 and Magnafloc 5250 flocculants acquired from Ciba Specialty Chemicals. Sand particles from phosphate flotation added to the clay slurry promoted flocculation and increased clay consolidation. K+ showed good performance to improve the flocculation characteristics by neutralizing clay surface charge. The adsorption mechanisms of flocculants on clay particles were also discussed in this paper.

Jan 1, 2006

By M. Fornaro, E. Lovera, I. Sacerdote

"The analysis of the mining laws of the different European States reveals big diversities and, often, remarkable complications. This is due, firstly, to the history and culture of different States and, secondly, to the assets of natural resources. It is therefore difficult to find a common line between the text of the various mining laws, but it can be observed that nearly all the States distinguish the mining resources in two categories: the materials whose importance is considered strategic belong to the first category; in the second category the materials whose importance (above all economic) is mainly local are comprised. The paper, analysing in detail the planning procedures in some important Countries, investigates the possible perspectives of arranging some guide-lines for a correct approach to the sustainable exploitation planning/programming of mineral resources (with particular reference to "quarry" materials, such as aggregates), considering both the environment protection and the production needs."

Jan 1, 2005

By W. P. Diamond, S. L. Cario, F. Garcia, J. D. Byars, T. P. Mucho

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research at a Pittsburgh Coalbed longwall mine to evaluate and optimize bleeder ventilation and gob gas venthole longwall methane control systems. Gas flow into these two methane control systems was investigated using a combination of Sulphur Hexafluoride (SF6)tracer gas studies and gob venthole pressure monitoring experiments. The insights gained from this research has facilitated the development of a longwall subsided strata methane control system conceptual model. This model provides the basis for design suggestions to increase the efficiency of the gob gas venthole system to permit the bleeder ventilation system to become a "safety net" for methane control.

Jan 1, 2000

By Zephaniah Varley, Satoshi Akai, Richard Sage, Steve Redmond, Mike Murray, Rohit Shetty, Gerald Skalla

One would be hard pressed to find another project as complex as this one given its configuration, the variety of issues to address and the required construction techniques. Contract C710 is currently under construction as part of Sound Transit’s Link Light Rail, connecting downtown Seattle with Sea-Tac Airport. The paper describes the construction-to-date of the deep mined station under Beacon Hill using the Sequential Excavation Method (SEM). This deep “binocular” station is being mined through some of the most challenging soft ground conditions in the USA. The excavated volume of the station is approximately 60,000 cy (46,000 m3) and the station comprises a variety of geometries and cross sections ranging from 235 sf (22 m2) up to 1,670 sf (155 m2). This underground complex includes platform, concourse, cross-passage and emergency ventilation tunnels together with station egress and ventilation shafts. Various excavation sequences are in use for the different tunnels including the twin-sidewall drifts for the impressive45 ft (13.7 m) wide by 42 ft ( 12.8 m) high concourse cross adits. This station has two train platforms approximately 165 feet (50m) below the surface. This station, constructed in highly variable glacial deposits including water bearing sands and silts approximately 50 ft below multiple perched water tables in an urban setting, creates a very unique and challenging situation. The ground is being managed with various types of ground improvements such as jet grouting and vacuum assisted deep dewatering wells from the surface, and from underground by use of “SEM Tool-box Items” such as barrel vault canopy, grouted pipe and rebar spiling, chemical grout,

Jan 1, 2007

By C. Allen

Vale Inco Ltd. is trialing several energy conservation initiatives in an effort to minimize costs and reduce green house gas emissions. The Ventilation on Demand (VOD) concept is a major project being carried out in various phases at Vale Inco mines. Due to the complex nature of a dynamic VOD system, Vale Inco is taking a systematic approach of testing VOD system components with milestone evaluations of each project. Coleman Mine was selected to pilot test the functionality and robustness of automated louvers in the underground environment; with the goal of optimizing mine airflow such that ventilation would be available for developing a new ore body. This project involved installing automated louvers in the exhaust raises; and installing variable frequency drive (VFD) starters on auxiliary supply fans. Because the VOD project created efficient utilization of the ventilation air in the 153 OB, the 170 OB is currently being developed without increasing the total fresh air into the mine. This paper describes the louver system component of VOD as applied at the mine.

Jan 1, 2009

By J. Z. Cheng

The extraction of thorium from industrial radioactive wastewaters discharged from Rare Earth (RE) plants was studied by the liquid membrane emulsion technique using P507- Span80-sulphonating kerosene-HCl. The emulsion conditions, the technological factors such as ratios of oil to the internal aqueous phase and water to emulsion, and the extraction time etc. were investigated.

Jan 1, 2008

By C. J. Roos

Ground engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these ?consumable? items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corporation to predict the consumption of excavator teeth. This paper presents the results of a Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2009

New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor?s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.

Jan 1, 2012

By M. H. Weinecke, B. P. Faulkner

This paper will discuss the process for making lightweight aggregate, the waste materials that make good lightweight aggregate, the chemistry of making lightweight aggregate and finally a discussion of the commercial prospects for making lightweight aggregate from wastes. Svedala Industries has been making lightweight aggregate (LWA) from waste materials for the last ten years. Many clay-like materials, such as coal-fired boiler ash and washings from a granite quarry, can be used alone or with additional waste materials to produce a commercially saleable LWA.

Jan 1, 2001

By S. Shaw

There is an increasing requirement for mines to meet a certain minimum criteria for sustainability within the context of the physical environment, ecosystem and socio-economic system in which they are located. The mining industry has wrestled to develop methods for assessing the ‘sustainability’ value of a mining project and indicators of ‘sustainability success’. A methodology for the evaluation of sustainability of a mining project using the Multiple Accounts Analysis (MAA) system was developed. The MAA is a platform for engagement of stakeholders and for the assessment of site-specific alternatives based on both qualitative and quantitative indicators of success.

Jan 1, 2004

By A. Duerksen

"Surface coal mining in West Virginia has supplied energy to the eastern coast of the United States for over a century. Over the years, the coal mining industry has been forced to adapt as societal demands regarding health, safety, and environmental impacts have changed. More recent pressure has called for another iteration of change: long-term post-mining sustainability. The research discussed in this paper investigates one potential solution - or component of a solution - to improve the sustainability of surface coal mining in West Virginia: post-mining wind power. The paper begins with an introduction to the Appalachian region of the U.S. and the role that mining has played in its history, followed by a discussion of the need for sustainable mining and how post-mining wind power may help fulfill it. Data processing methodology of field data from monitoring locations is then explained. The results are then used to estimate the electrical output of a wind turbine. This data is then utilized in a case study discussion of one of the monitored sites. The paper concludes with an analysis of the broader implications of the research and a discussion of future work."

Jan 1, 2011

By A. Habibi

The ventilation survey was conducted in an underground longwall trona mine. The mine is relatively shallow and categorized as a gassy mine. The ventilation system consists of nine shafts (three intakes and six exhausts). Three surface based axial fans ventilate the mine configured in a blowing arrangement. Following the ventilation survey airflow quantity, frictional pressure losses and air psychrometric characteristics have been quantified. An accurate resistance survey has been conducted to calculate the pressure drop with regard to moving cages and skips in the shafts. This paper discusses the benefits of utilizing high accuracy digital pressure transducers and psychrometers in a ?leapfrogging? survey to gather data needed to build the computer ventilation model. Two underground booster fans with VFD are currently idle but available at the mine. The ventilation model has been used to determine the optimal booster fan locations to decrease the overall operating cost by reducing the load carried by the main fans. A leakage study has been conducted to evaluate the effects on the system of additional pressure from a booster fan. The study finally prepares a future ventilation model for the next fifteen years of mine operation and investigates the effect of proposed scenarios.

Feb 27, 2013