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By S. F. Diehl

Weathered mine waste consists of oxidized primary minerals and chemically unstable secondary phases that can be sources of readily soluble metals and acid rock drainage. Elevated concentrations of metals such as Cd, Cu, Fe, Mn, Ni, Pb, and Zn are observed in deionized water-based leachate solutions derived from complex sedex and Cu-Pb-Zn mine wastes. Leachate (USGS FLT) from the Elizabeth mine, a massive sulfide deposit, has a pH of 3.4 and high concentrations of Al (16700 ug/L), Cu (440 ug/L), and Zn (8620 ug/L). Leachate from the sedex Faro mine has a pH of 3.5 and high concentrations of Al (2040 ug/L), Cu (1930 ug/L), Pb (2080 ug/L), and Zn (52900 ug/L). In contrast, higher-pH leachates produced from tailings of polymetallic vein deposits have order of magnitude lower metal concentrations. These data indicate that highly soluble secondary mineral phases exist at the surface of waste material where the samples were collected. Sulfide minerals from all sites exhibit differential degrees of weathering, from dissolution etched grain rims, to rinds of secondary minerals, to skeletal remnants. These microscale mineral-dissolution textures enhance weathering and metal leachability of waste material. Besides the formation of secondary minerals, sulfide grains from dried tailings samples may be coated by amorphous Fe-Al-Si minerals that also adsorb metals such as Cu, Ni, and Zn.

Jan 1, 2011

By Gennaro G. Marino

During the preliminary design stages of the Illinois Division of Natural Resources(DNR) building, it was discovered that an old coal mine was present some 70 m (220 ft) beneath the building site. The new DNR building to be constructed is 36 m (120 ft)wide and 134 m (440 ft) long. It has three stories above grade and abasement level. The building is oriented north-south and has east and west ponds next to it (Fig. 1). The building is located on the State Fairgrounds in Springfield, IL. Given the history of surface subsidence of these underground coal mines in the Springfield area, there was concern about the potential for future subsidence at the building site. Mine subsidence events in the area have resulted in more than 0.9 m (3 ft) of settlement and have caused significant structural damage.

Jan 1, 2000

By A. Nivala, S. Ulgiati, M. Canino

Mining and processing of bastnaesite ore, (Ln)CO3F, for lanthanides extraction is investigated in this paper. This series of elements proved to be applicable for a wide range of high-tech uses. In spite of the strategic importance of lanthanides, no LCA and energy analyses of their extraction have ever been published. We perform in this paper a Life Cycle Assessment of the Lanthanide production cycle, based on available database and literature data from Mountain Pass mine (USA) and other worldwide mining and processing sites, most of which in China. We investigated three main steps: mining, milling (including transport, grinding and drying), and flotation (for lanthanide chloride extraction). We do not investigate here the separation of pure oxides from lanthanide chloride, a compound which is also marketed as such. The conventional LCA was integrated by means of energy and emergy evaluations, aimed at investigating respectively the global energy cost and the environmental sustainability of the process. Indicators of material intensity, thermodynamic efficiency, and environmental impact (including LCA and ecological footprint impact categories) are calculated and discussed.

Jan 1, 2005

By TUIJA MONONEN, LUDGER BENIGHAUS, CHRISTINA BENIGHAUS, Virginia del Rio, SARI KAUPPI, JUHA M. KOTILAINEN, JAVIER GÓMEZ, JARI LYYTIMÄKI

The understanding of public debates over mineral exploration and mining largely originates from exceptional situations such as mining accidents of conflicts. Less is known about how mining is portrayed and understood under more conventional settings. What storylines dominate the local day-to-day public debate? This article presents results from a comparative case study focusing on newspaper coverage of mineral exploration and mining in three European countries representing different geological and socio-economic contexts. Newspaper articles from the Geyer-Erzgebirge region in Germany, the Andalusia region in Spain, and Northern Finland are studied. The sample looks into the period between September 2018 and February 2020 and shows that regional newspapers report about mining issues relatively intensively even in the absence of major accidents or other media events causing peaks of attention. The tone of the articles is generally neutral to positive towards mining activities, reflecting the specific local settings, historical experiences, and future expectations. Despite the different contexts of the three countries, there were considerable similarities to the topics highlighted, including common themes of mining revival, mining events and social interaction, history of mining, and damages related to mining. Past, present, and future employment opportunities related directly or indirectly to the mining sector are key storylines. Another recurrent underlying theme is the need to balance environment and safety risks and socio-economic prosperity, typically covered through ordinary disputes among the mining sector, public authorities, regional non-governmental organizations, and local initiatives.

Jul 6, 2021

One of the critical challenges facing the mining industry ? and not just in the United States ? is the looming labor shortage. A significant percentage of the industry?s professional workforce is, well, getting old, and many will be retiring in the next 10 years or so. This is not a new issue to the industry. It has been discussed at various industry meetings and conferences for many years. How does mining, with its largely negative public image, attract young people to mining schools? And, equally important, who is going to teach them? Mining schools, what?s left of them in the United States, are beginning to lose qualified faculty to retirements, and no one is available to replace them. SME addressed this issue during the keynote session at its annual meeting in February in Denver, CO. This year?s theme was ?Mining: It?s About the People.? Despite a blizzard that blanketed the city on the day most attendees were to have arrived, the meeting still attracted a record 7,202 people. And the accompanying exhibit sold 822 booths, also a record. The U.S. Department of Energy?s National Energy Technology Laboratory contracted with the National Academies? National Research Council to complete a study concerning the availability of skilled workers to meet the energy and mineral security requirements for the United States. The National Research Council, in turn, asked SME to collect and analyze workforce trends in these industries. The result of SME?s analysis is the report ?Emerging Workforce Trends in the U.S. Energy and Minerals Industries.? It is available on the SME website, www.smenet.org. Click on Government Affairs. While the report did not paint a completely dismal picture, there were some disturbing results. It concluded that within 20 years there will not be a sufficient number of skilled professionals to satisfy the labor demand. That said, the report said that most of those positions would likely be filled. However, the U.S. mining will go through a period of time when the workforce will be made up of very young and senior workers.

Jun 1, 2013

By Ralph P. Hackl

Ore at the Congress gold property, located near Goldbridge, British Columbia, is extremely refractory with most of the gold disseminated in fine-grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225m' (7950-cu ft) commercial size bioleach reactor was built and tested at the mine site in 1989. At that time, the tank was the largest bioleach reactor ever operated. The objectives of the program were: • to ascertain if the biooxidation rates obtained in lab and pilot-scale reactors could be duplicated in a commercial scale tank; • to identify agitation conditions under which the process will function optimally; and • to demonstrate the bioleach process on a scale sufficient to satisfy the owners and potential investors.

Jan 1, 1990

By Setareh Afrouz, Emily Sarver, Cigdem Keles

The resurgence of severe lung disease among US coal miners since the mid-1990s has led to efforts to better characterize and monitor respirable dust exposures, particularly focusing on mineral constituents from rock strata surrounding the coal. A rapid analysis method for silica (quartz) mass using direct-on-filter Fourier transform infrared (FTIR) spectroscopy has been developed, which can also estimate kaolinite, a primary silicate mineral in many coal mines.

Feb 24, 2022

By J. W. Hawkins, K. B. C. Brady, K. Miller, J. Cuddeback

Remining of abandoned coal mines in Pennsylvania requires the implementation of pollution abatement and mining techniques called Best Management Practices (BMPs). Water-quality data from over 100 remining sites with more than 230 abandoned discharges were analyzed with respect to the types of BMPs employed to abate the pollution loadings of acidity, iron, manganese, aluminum and sulfate. Discharges exhibiting a significant decrease in acidity were most highly associated with sites where large volumes of alkaline materials were encountered (66.7%) or added (63.7%). The best results for iron loading were achieved with large-quantity alkaline addition (54.6%) and water handling systems (47.8%). Water handling systems (47.4%), daylighting (40.7%), and revegetation (40.2%) were associated with significantly lower manganese loadings. The decreases in acidity and sulfate loads associated with increasing the amount of alkaline material in the backfill indicates that the production of acid mine drainage can be retarded by adding large quantities of alkaline materials.

Jan 1, 2002

By Kaixi Jiang, Chaozhen Zheng, Shuchen Qin, Hao Ma, Yufang Wang

The study investigates the behaviors of zinc and iron in neutralized residue during pressure and hot acid leaching. It examines the effects of temperature, acidity, leaching time, and oxygen partial pressure on zinc extraction. The results indicate that the acid to zinc mole ratio is crucial for the extraction process, with a zinc extraction rate reaching 98.0% under optimal conditions.

Feb 14, 2022

By Richard A. Thomas, III JAMES H. ROWLAND, Liming Yuan

This paper presents the results of large-scale fire experiments on evaluating the performances of carbon monoxide (CO) and smoke sensors at low ventilation velocities. Experiments using three different combustibles — conveyor belt, coal and diesel fuel — were conducted in the experimental mine at the U.S. National Institute for Occupational Safety and Health (NIOSH) Bruceton Research Facility. A total of eight sensor stations were located downstream of the fire with each station containing sensors for CO, smoke, carbon dioxide (CO2 ), oxygen (O2 ), humidity, barometric pressure and temperature, as well as two airflow sensors. The airflow velocity ranged from 0.22 to 0.26 m/s (44 to 51 fpm) in the tests. The response times were recorded for the CO and smoke sensors at each sensor station when smoke and gaseous products of combustion from each burning combustible reached the station. The response times of the CO sensors were used to determine the appropriate sensor spacing in the belt entry with a low air velocity. The performance of the smoke sensor was found to be affected by the high humidity in the experiments. The results on proper selection of sensors and the determination of sensor spacing at a low ventilation velocity can be helpful for ensuring sufficient early fire warning for underground workers, thereby improving the health and safety of miners.

By Poltak Sinaga

PT Kaltim Prima Coal?s 13.1 km overland conveyor (OLC) was commissioned in 1991. It is of conventional 3 roller 350 trough belt type. Cost and performance optimization during initial design ended up with 5.4 mps belt speed, 1000 mm belt width to convey 1350tph, and 7 mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30 mtpa (million ton per annum). Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4 200 tph satisfactorily.

Jan 1, 2008

By Ananta L. Yennamani

Blast movement measurement (BMM) transmitters are a practical method to measure three-dimensional (3D) rock movement because of blasting. The BMM transmitters are activated, programmed and installed in specially designed drill holes prior to the blast and the BMM detector locates the transmitters after the blast. The BMM software then calculates and summarizes the 3D movement of each BMM transmitter ball. This information helps to redefine the ore and waste boundaries and enables improved ore and waste selection, resulting in a genuine step change in grade control. The BMM program was carried out at Newmont Mining Corp.?s Phoenix Mine, in northern Nevada near the town of Battle Mountain. The mine is in a historic mining district that contains gold, silver and copper. The geology of the pit consists of different formations made up of sandstone, siltstone, limestone, chert-pebble conglomerate, shale, skarn and quartzite, to name a few. Some of the rock is extremely hard and a powder factor of up to 0.5 kg/t (1 lb/st) is required to get adequate fragmentation to ensure sufficient throughput through the crusher and the mill. The result of using such a high powder factor translates into considerable blast movement and heave. This movement means that the ore/waste digging polygons estimated by the ore control engineer from sampling the initial blast holes will no longer be located in their original posi-tions. The purpose of this project was to test the measurement method and to see if locating the digging polygons in the broken muck pile and excavating to those polygons will improve grade control through the mill. Case studies (Zhang, 1994), (Taylor, 1995), (Gilbride, 1995), (Harris, 1997), (Taylor, 2003), Barrick Goldstrike (Gold-strike Mine, 2008), Ruby Hill Mine (Hilkewich, 2009), (Porcupine Mine, 2005) and (Aguirre, 2010) have shown that, by accounting for the blast movement, there is a potential to increase mineral recovery by as much as 25 percent for individual blasts for only a modest cost increase.

Jan 1, 2011

By N. Cruickshank

Gas outbursts occur as sudden eruptions of gas and minerals from the face of a mine heading as the heading approaches potentially burst-prone (or anomalous) zones of rock. Such outbursts have resulted in considerable damage to equipment and in some cases lives have been lost. Characterizing these anomalous zones and detecting their presence is therefore vital to safe mining. Certain significant characteristics associated with the outburst-prone zones are: (1) the presence of fluid inclusions, (2) unstable stress conditions, (3) characteristic geologic structures, (4) certain physical properties of the rock, and (5) micro-seismic activity. Geophysical and engineering methods for detecting these characterisitcs are discussed and are considered with respect to their past success and future potential for predicting gas outbursts.

Jan 1, 1985

By George Hope, Edward H. Smith

In late 1989, LAC Minerals purchased 65% of Bond International Gold and as a result became controlling shareholder of the El Indio Mine through Bond and San Jose. El Indio is a world class, complex sulphide gold deposit located in the hydrothermal alteration belt of the Andes mountains in the 4th Region of Chile. The mine is located in the high Andes about 185 km east of La Serena at an elevation of 4000 meters. The 1450 workers at El Indio live in the mine camp at 3200 m and on days off are bussed to La Serena. The El Indio mine was started in 1979 by St. Joe Minerals Corp., bought by Bond in 1987 and subsequently by LAC in 1989. The mine has produced 2.7 million oz. of gold, 9. 5 million oz. of silver and 170,000 t of copper since start of operation. The mill is currently operating at a rate of 2850 t/d and producing a copper/gold concentrate which is roasted to produce a copper/gold calcine and high quality, saleable crude As203• A small proportion of the precious metals are also produced as bullion from the leach circuit. Total production during 1989 was 224,197 ounces of gold, 1,309,342 ounces of silver and 26,968 tonnes of copper. The average cash cost of production for the period was U.S. $96 per ounce of gold, net of by-product credits. The average realized price was $5.30 per ounce of silver and $1.14 per pound of copper.

Jan 1, 1990

By Birger Schmidt

INTRODUCTION Conceptual design of the first Exploratory Shaft (ES-I) for the Nuclear Waste Repository in Basalt (NWRB) began in July 1981; detailed design began in February 1982, and was largely completed by December (RKE/PB, 1983). The intent was to begin shaft construction by January 1983. The site had been prepared at that time, a construction manager selected and on board, the starter hole excavated and lined, and steel casings were under procurement. Government policy changed, however, and construction was halted before the drill rig started turning. Construction is now planned to begin in 1988. ES-I is a part of the site characterization program for the NWRB. The shaft will be used to develop production data and related information relative to drilling shafts at the site near Richland, WA, and to provide access to the repository horizon for site characterization and testing. The early program called for one shaft and some 330 m (1000 ft) of drifting. The program has since expanded to include a second shaft (ES-II) and more extensive drifting and testing. Currently, both shafts are planned to be 1.8 m (6 ft) in finished diameter, but studies are underway to determine if the second shaft should be larger. The drilling method was selected for shaft construction primarily because it offered a significantly shorter construction period than conventional shaft sinking using freezing and grouting. The finished drilled shaft will be lined with a continuous steel lining. Personnel are safer during construction with a drilled shaft than with a conventionally sunk shaft. The drilling method

Jan 1, 1987

By James J. Meadows, Jason D. Pampena, Emanuele G. Cauda, Lauren G. Chubb

Exposure to respirable crystalline silica (RCS) can cause serious and irreparable negative health effects, including silicosis and lung cancer. Workers in coal mines have the potential of being exposed to RCS found in dust generated by various mining processes. The silica content of respirable dust in one single mine can vary substantially over both time and location. The current monitoring approach for RCS relies on the use of traditional air sampling followed by laboratory analysis. Results generated using this approach are generally not available for several days to several weeks after sampling, and this delay prevents timely and effective intervention if needed. An alternate analytical method is needed to reduce the time required to quantify the RCS exposure of mine workers. The National Institute for Occupational Safety and Health (NIOSH) has developed a new method using commercially available portable infrared spectrometers for measuring RCS at the end of the sampling shift. This paper will describe the application of the new field-based RCS analytical process for coal mines, including the use of the new method with the existing Coal Mine Dust Personal Sampler Unit. In a case study conducted by NIOSH with a coal mine operator in West Virginia, field-based RCS analysis was completed at a mine site to evaluate the new technique. The RCS analysis results obtained by the field-based method in this case study showed sufficiently strong correlation with results obtained by the MSHA standard laboratory analysis method to allow the mine operator to use the field-based method for evaluating process improvements.

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By R. D. Williams

In spite of the increasingly polarized and politicized view of climate science and climate change in the United States, many of the principles behind the ?theory? of Anthropogenic Global Warming (AGW) or Global Climate Change (GCC) are in fact firmly established both in fundamental physics and detailed observations and are widely accepted elsewhere. The discovery of the earth?s ?greenhouse effect? dates back nearly 200 years to the work of French mathematician and physicist Joseph Fourier in 1824 and 1827. In 1872, John Tyndall an English physicist and mountaineer, described the capacity of various gasses to absorb radiant heat. He identified water vapor and carbon dioxide as the principal ?greenhouse? gasses. The work of Fourier and Tyndall was the foundation for the theory that increasing carbon dioxide (CO2) in the atmosphere might be responsible for an increase in global temperatures developed by the brilliant Swedish chemist Svante August Arrhenius in 1896. This was backed up by the additional work of Gilbert Callendar in the 1930s, and Gilbert Plass, Hans Suess and Roger Revelle in the 1950s. There is little scientific dispute about the physics by which this occurs: carbon dioxide in the atmosphere absorbs long wave radiation that would otherwise escape into space, thus warming the lower atmosphere and respective temperatures worldwide. The Intergovernmental Panel on Climate Change (IPCC), approximately 2500 climate scientists from around the world, has concluded that increases in carbon dioxide resulting principally from the burning of fossil fuels are responsible for most of the continuing increases in global temperatures (IPCC, 2007). NASA?s Goddard Institute for Space Studies (GISS) states; ?The ten warmest years all occur within the 12-year period 1997-2008? (GISS, 2009). 2009 was the second warmest year on record and 2010 was tied with 2005 for the warmest year on record (GISS, 2010, 2011). The science is in fact settled; the earth has not cooled since 1998 as some have claimed. It continues to warm as evidenced by not only surface temperature records but also ocean temperature records as well as changes in physical and biological systems (IPCC, 2007).

Feb 27, 2013

By S. K. Kawatra, J. A. Halt

"Low-grade iron ores are finely ground and processed to recover iron-bearing minerals. However, the iron-rich powder is too fine to be used directly in blast furnaces and most direct reduction furnaces, and must be agglomerated or pelletized into a usable product called “pellets.” Bentonite clay has traditionally been used as a binder to make iron ore concentrate pellets, but it is expensive and contaminates the pellets. Organic binders may be a viable alternative to bentonite clay. This manuscript reviews organic materials that have been used to make iron ore concentrate pellets. Included are discussions on the development of organic binders, common pros and cons to organic binder use, organic binder structure and its effects on agglomeration, and additives to organic binders.IntroductionIron ore agglomeration turns finely disseminated, low-grade iron ores into a usable product, called pellets. During pellet production, fine-grained, iron-rich minerals are liberated from low-grade ores, concentrated, and agglomerated into round balls that are thermally hardened or cold-bonded to form pellets. Pellets are then transported to blast furnaces or direct reduction operations where they are used to produce iron; iron is further refined and shaped into the wide variety of steel-based industrial and consumer products in use today.Over the years, pellet production has become increasingly more prevalent with the increased exploitation of low-grade iron ores and increased iron and steel consumption around the world. In 2010, world iron ore pellet production was 388 Mt. It could be argued that the current pellet production process has been enabled by the use of binders – practical experience has shown that it would be nearly impossible to agglomerate iron ore concentrates using rotary drums and discs without using a binder."

Jan 1, 2015

By J. Kretschmann, N. M. Smith, J. F. Brune, P. Goerke-Mallet

Coal production and coal use for electric power generation are diminishing worldwide. Germany will phase out lignite mining as well as lignite and hard coal-powered electricity generation by 2038. In the United States, coal production has dropped by more than 50% since 2006, including in key coal production states like West Virginia and Wyoming (EIA 2021). Closing mines and power plants across entire mining regions has significant socio-economic impacts. Existing industries must be focused on the post-mining economy by attracting new industries, and implementing job retraining programs for displaced workers, as former mining regions transition towards agricultural, industrial and recreational use. This paper examines the German “exit from coal” under the 17 UN Sustainability Goals and illustrates the complex procedures, interrelationships, risks, and rewards of the transition towards renewable energy sources, including wind, solar, hydrogen, and bioresources.

Mar 2, 2022