Search Documents

By G. J. Joy

Although rates of pneumoconiosis in coal miners have declined substantially in the United States since the passage of the Federal Coal Mine Health and Safety Act of 1969, new cases continue to occur, including cases of rapidly progressive disease. In contrast, Australia's underground coal mining industry has reported few new cases of pneumoconiosis for more than 20 years. Mortality from coal workers' pneumoconiosis in official health statistics and the prevalence of pneumoconiosis among miners screened in X-ray surveillance programs are also lower in Australia. The U.S. National Institute for Occupational Safety and Health (NIOSH) was requested by both industry and labor stakeholders to examine this issue, with the ultimate aim of reducing the rate of pneumoconiosis among U.S. coal miners. A number of factors, including coal dust exposure, silica exposure and coal rank were examined as potential contributors to the above noted differences. Comparison of coal rank data from each country did not illuminate the issue. Air sample data from the coal mining industries in both countries show that coal dust levels in Australian mines are somewhat higher than those reported in similar U.S. mines; however, quartz exposure for Australian miners is lower than for many U.S. miners. If quartz is contributing to the greater number of cases of pneumoconiosis in the United States, more effective dust control measures, as well as an independent exposure standard for respirable quartz in coal mining, should be implemented to reduce this potentially disabling condition.

Jan 1, 2012

By D. K. Denton, M. J. Friedel, D. F. Scott, T. J. Williams

Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions, and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep ( > 1220 m) underground pillars. If high-stress areas are detected, they can be destressed prior to development or avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient, and non-invasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress, engineers will be able to assure that miners are working in a safer environment.

Feb 24, 1997

By X. Shi

This paper presents design and implementation details of a fuzzy-behavior-based controller for an automated excavator. The robotic excavator is equipped with sensors, actuators and an embedded control system. The excavator controller uses neural-networks to interpret forces and torques gathered during the excavation process from bucket-mounted force sensors. Implementation details card experimental results using the fuzzy-behavior-based excavation controller are given for several excavation tasks. These excavation tasks demonstrate some of the complex skills that are essential for an autonomous mining-excavator controller.

Jan 1, 1997

By I. T. Oramah

Despite the abundance of solid mineral deposits, Nigeria only earns about 0.5-1% of its current Gross Domestic Product (GDP) from the solid minerals sector. This is as a result of the dominance of the oil and gas industry, which has negatively affected the competitiveness of other sectors of Nigeria’s economy. The dominance of this industry has resulted in unemployment, poverty, hunger, domestic price inflation, corruption, unstable government, and higher exchange rates. These impacts are typical for economies suffering from the effects of "Dutch Disease" and the "Resource Curse". Community-based small-scale mining offers hope as an economic activity that can create wealth, employment, reduce hunger and poverty, and provide basic amenities for rural communities with solid minerals endowment. This study presents preliminary results of ongoing research into the prospects of using community-based small-scale mining in a developing country like Nigeria to move towards rural sustainable development.

Jan 1, 2011

By D. F. O?Connor

The health & safety of all workers in an underground environment is paramount to the success of our operations. The diesel emission reduction projects are key to improving such an environment. However, care must be taken to reduce the risk to personnel during such tests and prevent exposure to other hazards. VALE Inco works in a close partnership with its unionized employees, manufactures, suppliers, researchers and government officials to ensure projects are done safely and efficiently to successful completion. The Creighton Mine Diesel Particulate Filter (DPF) project is an example of such a project that is currently under way to evaluate new and innovative technology that will further our search for improved environment for our workplace. This paper will discuss the issues and processes that are followed to ensure Diesel Particulate Filter (DPF) field tests are conducted safely and productively.

Jan 1, 2009

By D. W. Rich

An environmental management system (EMS) is a key part of a company?s environmental stewardship. Procedures and practices to continually improve environmental performance can provide great benefits in operating the company. Managing site environmental quality data is a key component of this. An environmental data management system (EDMS) is an important element of the EMS for mining and other projects, providing project staff with the information that they need to make decisions that can have a significant impact on public health. Improvements in computers, data communications, and transfer formats have made it much easier to implement an integrated EDMS program for gathering, managing, selecting, and displaying data from the field and the lab. Software now lets users define sampling plans, create files for field data entry, and print Chains of Custody. Laptop and handheld computers facilitate field data entry and may provide automated communication back to the office. Most labs can now create usable electronic data deliverables. QC checks and limit comparisons can be largely automated. The result is organized data that can be efficiently used for reporting, graphing, and mapping, to better understand project issues.

Jan 1, 2009

The National Mining Hall of Fame will hold its 13thAnnual Induction Banquet during MINExpo International 2000 in Las Vegas, NV. The gala black-tie (optional) event will honor eight legendary leaders of the mining industry. The event will take place at the Las Vegas Hilton Hotel on Sunday, Oct. 8. The induction ceremonies will salute mining greats elected by the board of governors from a list of nominees submitted by mining industry partners and the public. The members of the Class of 2000 will join 151 other inductees enshrined in the Mining Hall of Fame in Leadville, CO. The evening will begin at 6 pm with a cash bar reception followed by the banquet and program at 7 pm. Keynoting the banquet program will be Harrison (Jack) Schmitt. He was the geologist/astronaut of the Apollo 17 mission to the moon in 1972 (see related story on page 26). And he is the only scientist to “kick rocks on the moon.” Schmitt is also a member of the Mining Hall’s board of governors. Schmitt was also the keynote speaker at the First Annual Induction Banquet in Denver, CO in 1988.

Jan 1, 2000

By W. Blake, J. Whyatt

Sixty years of rockbursting in the Coeur d’Alene district has taught painful lessons and led to a number of practical advances in controlling rockburst hazards. This paper summarizes those lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. These lessons are explained in the context of district mining history and current understanding of rockburst phenomena. Overall, the paper provides the practicing mine engineer with an appreciation of rockburst hazards and an overview of practical measures that can be used to control these hazards in the context of Coeur d’Alene district experience.

Jan 1, 2002

By Paul C. Schmall, Thomas Tuozzolo, Arthur B. Corwin

The Lenox Avenue Reconstruction Project involved the excavation and replacement of 750 m (2,500 ft) of deteriorated subway invert concrete, 5 to 7 m (15 to20 ft) below water table in very permeable ground. The Replacement work was done over an 8 month period, while maintaining track service through this subway section. The project was dewatered with a single 125 l/s (2,000 gpm) wellpoint system,750 m (2,500 ft) in length, which was installed from inside the active tunnel structure and configured to coexist in the subway tunnel with operating trains as well as the construction activities. A thin diaphragm jet grout wall was utilized on one end of the site to cut off the flow of water across a difficult geological interface that was situated immediately below the tunnel invert. The thin diaphragm jet grout wall permitted the large 116th Street Station area to be dewatered completely with well points from outside of the excavation.

Jan 1, 2001

By D. R. Wilburn

This summary of international mineral exploration activities for the year 2005 draws upon available information from literature, industry and U.S. Geological Survey (USGS) specialists. It provides data on exploration budgets by global region and mineral commodity and identifies significant mineral discoveries and exploration target areas. It also discusses government programs affecting the mineral exploration industry and presents analysis of the mineral industry based on these data. Two types of information are reported and analyzed in this annual review of international exploration for the year 2005. They include budgetary statistics provided by Metals Economics Group (MEG) and information on regional and site-specific exploration activities in 2005 compiled by the USGS.

Jan 1, 2006

By R. Strandahl

As one of the largest private utilities globally, E.ON currently operates hard coal fired power stations in with a total installed capacity of some 20.000 MW: These thermal power plants consume domestic coals but are increasingly dependent on imported seaborne traded coal (in 2009 approx. 17 million t). Knowing that the company’s reputation and credibility depends in part on how E.ON lives up to the responsibilities along the entire energy value chain, E.ON takes a collaborative approach with the various suppliers. Hence, E.ON’s responsible policy also applies to the procurement of coal; the utility launched in 2009 a comprehensive Corporate Responsibility program with special focus on supply-chain audits. One of the first coal audits focussed on the Cerrejón coal mine in North Eastern Colombia. The authors will share the key learning’s and experience from the Colombian audit jointly conducted with an independent auditor and E.ON experts from the Corporate CR and E.ON Energy Trading.

Jan 1, 2011

Introduction Aggregate mining impacts on water resources are a source of concern to local governments. To evaluate those impacts, the Minnesota Department of Natural Resources conducted a four-year study at three gravel pits (two alluvial and one beach-ridge) and five quarries (flat-lying Paleozoic limestone). This research provides the first comprehensive look at aggregate mining impacts on ground-water systems in Minnesota. The results will be used by government officials making permitting decisions about aggregate operations and by responsible owners of aggregate mines as they plan their operations to avoid conflicts with neighbors and with resources dependent on ground water and surface water. Natural aggregate (crushed stone, sand, and gravel) is a vital part of our economic infrastructure in Minnesota. Aggregate is used for road and bridge construction and in a variety of building materials. In 2003, the value of construction sand and gravel and crushed stone in Minnesota was approximately $245,000,000. As Minnesota’s economy continues to expand, the demand for aggregate will continue to grow. Sand and gravel pits are located in every county in Minnesota. In 1990, the Minnesota Department of Natural Resources, Division of Minerals (DNR Minerals), estimated the number of active and inactive operations at 1500 with the view that this number was likely too low. Quarries for mining limestone, dolomite, sandstone, and hard rock (granite and quartzite) are found in 34 counties. A 1990 DNR Minerals inventory found 165 active operations, 88 percent of which were limestone quarries (Nelson and others, 1990). That same inventory counted 1,367 inactive operations, 70 percent of which were limestone quarries. Aggregate mining is an extractive use of resources: mining alters the landscape and its natural hydrologic system. When a new pit or quarry is proposed or when an existing operation needs to expand, local governments and citizens typically have many questions about the impacts mining might have. Local governments, which are responsible for reviewing these operations, rarely have the budgets to hire experts to evaluate potential impacts of quarry and gravel pit proposals. The Minnesota Legislature’s Aggregate Resources Task Force identified that local government units (LGUs) often lack the expertise to assess ground-water models (Southwick and others, 2000).

Jan 1, 2007

By U. Richter

Conveyors are a highly effective means of transporting material over long distances. Recently there has been a trend toward long conveyor systems with high capacity single flights. These conveyor systems are an efficient alternative to costly truck fleets. Also with deeper mines, the use of diesel driven trucks becomes more difficult. Another trend is in underground mining, where conveyors are an efficient alternative to drift hoists or dedicated rail systems.

Jan 1, 2012

By S. Suwansawat, D. J. Maconochie, C. C. Chang

This paper describes the overall delivery of the tunneling for the Mass Rapid Transit Authority of Thailand’s Chaloem Ratchamongkhon Line in Bangkok and the constraints provided by the alignment. Eight earth pressure balance tunnel boring machines were employed under two major civil works contracts to drive approximately33 kilometers of tunnel in soft saturated ground beneath the crowded streets of Bangkok. Responsibility within the contract for building damage provided an inherent control for ground movement arising form tunneling when the right of way was narrower than the influence zone. These limits affect the earth pressure balance requirements and permissible ground loss. The methods adopted to limit ground movements and deal with the various obstacles to tunneling influenced the design and operation of the machines. The challenges provided by the need to tunnel through numerous lines of piled foundations of canal bridges and overpasses crossing the alignment are described.

Jan 1, 2001

By Ray Brainard

The subsurface investigation for the Reach 4 Tunnel was expected to be completed in a single phase. This assumed that data from two nearby previous tunnels, combined with limited new subsurface information and surface mapping would be sufficient to characterize the rock behavior. Unforeseen rock conditions and complex faulting led to the recommendation for a second phase. This decision was not reached easily, as much of the follow-on work required helicopter support, and associated costs. The second phase of drilling found significantly more variability than the first phase and led to a very different and better understanding of the geologic and geotechnical conditions, and rock characterization.

By K. G. Kebkal, R. Bannasch

"Because the operation of tethered underwater vehicles in the deep ocean or under drifting ice areas is very complicated or impossible, the application of autonomous underwater vehicles (AUV) is preferred or even the only possible solution. However, this implies the possibility of a direct and real-time control over all AUV functions, which is only achievable with the availability of accurate positioning/navigation and a high-speed communication link. This paper presents a flexible bottom- or surface-based solution enabling high positioning accuracy of underwater objects (harvester, AUVs, bottom nodes); specifically, a multifunctional system that combines Ultra Short Baseline (USBL) transceivers and Long BaseLine (LBL) stations deployed at a large depth. Moreover, each baseline transponder is equipped with a high-speed communication device to provide the means for real-time AUV control based on the information about its current position, e.g. navigate it with direct commands and operating its actuators and other mechanisms. Moreover a communication link with a high data rate can provide valuable visual information from the operation area.Depending on how many nodes the LBL grid comprise has, target transponder positions can be estimated with an accuracy of several to tens of centimetres. The purpose of the paper is to present the experiments with all key elements of the multifunctional Hydro-Acoustic USBL-aided LBL Positioning and Communication System."

Sep 1, 2014

By John L. Kaplin

The underground construction for the Phase I Combined Sewer Overflow(CSO) Project is on an impressive scale by any measure, appearing more so in a midsize city like Providence, RI. The Narragansett Bay Commission recently completed $350 mil-lion in construction to improve the water quality in Narragansett Bay. This project included a number of serious challenges, delays, and disputes. Looking back on this complex project completed within budget, it is hard to consider the work as anything other than a success. Along the way, this outcome did not always appear certain.

The SFR system utilizes a skimmer or extractor placed at or near the slurry-froth interface where there is a higher concentration of valuable mineral particles. With assistance of hydrocyclones, it is possible to classify the extracted particles into coarse and fine particle streams, that can be handled separately. It also allows the coarser solids to be separated from entrained low-value fines. The first test results with the SFR system significantly improved both coarse and fine particle recovery in a flotation cell. The SFR system was tested in the flotation circuit at a copper-moly concentrator, and the results show that the use of the skimmer has huge potential to increase the froth recovery (Rf) of both molybdenum and copper.

Jan 1, 2012

By M. Gouet-Kaplan, J. A. Finch, S. Gélinas

Methylisobutyl carbinol (MIBC) and methoxy polypropylene glycol (Dowfroth 250) bubble thin films were characterized by composition and thickness determinations, using FT-IR spectroscopy and UV-Visible spectrophotometry, respectively. The infrared investigation indicates that the role of frother molecules in creating bubble thin films is based on their effectiveness in inducing H-bonding reorganization of the surrounding free water molecules into a coherent network. From UV-Visible interference patterns, it is found that MIBC forms films with a measured critical end thickness of less than 160 nm, compared to 612 ± 30 nm for Dowfroth 250. The observed values of the free water layer thickness are comparable at 5.65 ± 0.28 µm for MIBC and 6.75 ± 0.34 µm for Dowfroth 250. A higher stability of an MIBC bubble over a Dowfroth 250 bubble is related to the different polarization and orientation of the molecules sustaining the boundary surface water network. The findings are used to explain the different action and associated froth characteristics of the two common industrial frothing agents.

Jan 1, 2006

By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994