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By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By W. J. van Wyk, W. I. Mahne, G. Priest, C. du Toit, W. A. Liebenberg

Prior to the Coalbrook disaster in 1960, bord-and-pillar mining of the number two seam in the Witbank coalfields often resulted in small pillars with low factors of safety. At the Goedehoop Colliery, number two seam pillar stability is also affected by top and bottom coaling, while at Greenside Colliery, stability was further reduced by additional loading from a surface mineral residue deposit. This compromised the stability of the number two seam workings, impacting the safe mining of the overlying number four seam reserves. To extend the life of mine of both operations, an alternative risk management approach using designated enhanced monitoring districts was implemented to safely mine the number four seam reserves. This paper presents the use of geophone arrays to monitor micro-fracturing in number two seam pillars and the interburden between number two seam and number four seam, thereby enabling early detection of potential instability during overmining of the number two seam. Risk was assessed using fault and event tree analyses to determine acceptable failure probabilities. Automated seismic data processing distinguished micro-fracturing from noise, supported by extensive evacuation procedures for effective risk management. This approach facilitated the safe extraction of 4.70 Mt of number four seam coal. The study quantifies the efficacy of geophone monitoring in optimising coal recovery over low factors of safety pillars and assesses the application of Van der Merwe’s (2019) time-based formulae for pillar stability analysis for this project.

May 8, 2026

By David Jones, Jeff Bregar, Damien Bell

We have analyzed overpressure and ground vibration measurements for construction blasting for a large pipeline project. These field-measured levels have been compared to existing prediction curves in the literature and new curves have been proposed for overpressure and ground vibration for pipeline construction blasting activities.

Feb 1, 2020

By Richard H. Lindgren

I appreciate this opportunity to discuss with you OPIC's new policies designed to assist U.S. minerals companies in developing new sources of minerals overseas. A comparison of recent figures on U.S. investment in mineral exploration, development and production gives results which are remarkable --and disturbing. Through the 1960's the flow of U.S. foreign direct investment in mining and smelting in the developed and less developed countries were nearly equal. However, by 1973, roughly 80% of all exploration expenditures by mining companies was taking place in the developed countries and principally in the U.S., Canada and Australia. Clearly it is to the interests of both the developing countries and the United States to put these figures back in better balance. As you may be aware, the administration as a whole is examining systematically what can be done by government to reduce the disincentives and increase the incentives to mineral investment in the less developed countries --the LDCs. A subgroup of the National Advisory Council chaired by the Treasury Department has been formed to coordinate U. S. Government policy and program efforts relating to mineral and energy development in these countries. Among other matters, this subgroup will examine how public policies could positively influence the private investment decision-making process in the minerals industry.

Jan 1, 1978

The Australian Mineral Industry's growth in the last two decades is directly related to the skill and experience of its consultants in mining, metallurgy, geology, finance, management, marketing, and engineering. The role of mining consultants needs to be re-examined, so that the quality of the service they deliver will continue to be adequate for the 1990's. One means of this evaluation is by examining Case Studies in the strategies and difficulties of developing contract and entrepreneurial research.

Jan 1, 1986

By Robert L. Sundeen, Richard V. Wenberg

Overshot loaders are loading machines which fill a front-mounted bucket by crowding and bucket lifting, passing the loaded bucket over the machine and throw¬ing the load into a haulage unit to the rear. The load is retained in the bucket as the load mass is accelerated in its path over the machine. At the point of discharge, the bucket is stopped suddenly and the load leaves the bucket, following the throw trajectory past the rear of the loader. Fig. 1 shows a typical overshot loader of this type. Overshot loaders were developed for loading in nar¬row drift headings and drawpoints, where it is impossible to place or pass a haulage unit alongside the loader. Haulage access is to the rear of all overshot loaders. The first overshot loader was developed in the early 1930s. The early machines were rail-mounted, air¬powered, and had small loading capacities. To this day, the same basic design configuration exists, and all suc¬cessful overshot loaders still use compressed air. Bucket sizes range from 0.14 to 0.59 m3 (5 to 21 cu ft). The most commonly used machines are rail-mounted, al¬though crawler versions are popular for special applica¬tions, particularly shaft sinking. Rubber-tired machines have found some application where a greater travel distance is required between the loading and discharge points. CONDITIONS INFLUENCING APPLICATION Roadway Type Rail-mounted loaders are used where soft bottom requires rail support or where the long haul is ac¬complished with rail. This situation usually occurs in civil tunnels or in mine drifts that will continue to utilize rail-bound main haulage after development work is completed. Crawler and rubber-tire mounted loaders are used where the roadway surface is rough and lateral travel beyond the range of rail-bound machines is required. Work Area Dimensions The largest rail-bound loaders can clean roadways as wide as 4 m (13 ft) from a single track. Wider headings require multiple trackage. Headroom require¬ments are dependent upon the path described by the bucket as it passes over the machine. The largest over¬shot loader requires approximately 3.4 m (11 ft) of headroom. It follows that the largest heading that can be driven by overshot loaders from a single set of rails is approximately 4 m (13 ft) wide and a minimum of 3.5 m (11.5 ft) high above the rail. The smallest rail-bound loaders can work efficiently in headings as small as 1.8 m (6 ft) wide by 1.8 m (6 ft) high above the rail.

Jan 1, 1982

By Nolan Eckroade

The demand for blast optimization within the quarrying industry calls for more effective, faster and safer methods of quantification of blast performance. Drones provide the ability to safely and quickly capture high resolution imagery of a muckpile for use in fragmentation photo analysis. Oversize material within a muckpile is an expensive and universal problem affecting quarries, especially in situations where cap rock is present. Although the amount of oversize material in a blast is a key indicator of blast performance, it is difficult, hazardous and slow to measure across an entire muckpile using traditional methods. By piloting a drone using an automated flight plan with set amount of overlap across images, the images can be processed into a single, high resolution orthomosaic image for use in fragmentation photo analysis software.

Jan 1, 2018

By R Pinksen

The Iron Ore Company (IOC) of Canada Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1 m × 1 m × 1 m) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures.One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion into the blastholes provided more resistance to the forces created by dynamic water and reduced the infi ltration of the emulsion into the cracks and fissures of the rock mass. Blast results showed reduced amounts of oversize and more consistent fragmentation throughout the muck piles. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realised.To determine the effectiveness of the oversize reduction project, IOC used shovel based camera technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with global positioning system (GPS) locations. A large population of digital images was analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jul 11, 2011

By Rodney Pinksen, Remi Proulx

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures.

Jan 1, 2011

The Iron Ore Company of Canada (IOC) is the largest manufacturer of iron ore pellets in Canada and its customer base covers North American, European and Asian steel producers. The company operates a mine, concentrator and a pelletizing plant in Labrador City, Newfoundland and Labrador, as well as port facilities located in Sept-Iles, Quebec. It also operates a 418-km (260-mile) railroad that links the mine to the port. IOC has approximately 1,900 employees. Its shareholders are Mitsubishi Corp. (26.18 percent), Labrador Iron Ore Royalty Income Fund (15.1 percent) and the international mining group Rio Tinto, which is its major shareholder (58.72 percent) and operator, with activities in more than 40 countries throughout the world. The IOC was incorporated in 1949 and by 1954 it had completed the Quebec North Shore and Labrador (QNS&L) rail line. IOC began mining in Schefferville, Quebec by 1954 and closed those operations down in 1982. In 1962, IOC commissioned the present day Carol Project consisting of mining, concentration and pelletizing facilities in Labrador City, Newfoundland. In 2004, IOC shipped its one-billionth tonne of ore on the QNS&L Railway. In 2005, IOC celebrated 50 years of mining history. The company expressed an interest in reducing the amount of oversize material (>1 m x 1 m x 1 m or 3.2 ft x 3.2 ft x 3.2 ft) being produced and its subsequent downstream effects, including in-pit sorting and reduction, damage to mobile equipment and significant delays in the loading pockets and the primary crushers. To achieve this goal, an oversize reduction project was undertaken by the mine that, to date, has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduced the infiltration of the emulsion into the cracks and fissures of the rockmass, resulting in reduced amounts of oversize and more consistent fragmentation throughout the muckpiles. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analyzed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By R. Pinksen

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduces the infiltration of the emulsion into the cracks and fissures of the rockmass. Reduced amounts of oversize and more consistent fragmentation throughout the muckpiles has been a result. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a of first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A Digital Vision System (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

"With up to 2,300 m (7,545 ft) of rock on top of it, the Gotthard Base Tunnel, which is scheduled to go into regular operation in December 2016 in the Swiss Alps, is not only the world’s longest, but also the deepest railway tunnel ever built. Accordingly, the temperatures in the tunnel are very high, with the surrounding rock expected to reach 45° C (113° F) once the tunnel is fully operational. Since unrestricted rail operations are only permitted in temperatures of 40° C (104° F) or less, the heat has to be controlled with suitable equipment. Large fans developed and built especially for this application by TLT-Turbo GmbH provide fresh air for regular operations as well as during maintenance and repair work. Separate fans ensure that the emergency exits are properly ventilated in case of fire. In addition to coming up with a technical solution that could handle the special challenges of this project, the engineers and planners had to develop detailed preliminary plans as well as a sophisticated logistics and installation concept.The Gotthard Base Tunnel consists of two 57-km (35-mile) long tubes, one in each direction. Including all connecting and access tunnels, the entire underground system measures 152 km (95 miles). At Faido and Sedrun, at approximately 16 and 36 km (9 and 23 miles) respectively, two multifunction stations were built that cut each of the two tubes into three sections of roughly equal length. Here, trains can make emergency stops and change tracks, if necessary. This is also where eight large axial fans made by TLT were installed that exchange the air, i.e. they extract a certain amount of heated air and inject the same amount of cool fresh air a few hundred meters further down the train tracks. In addition to the four exhaust and four supply fans, 24 so-called jet fans were installed along with associated components like silencers, shut-off dampers, drives and lubrication systems from TLT.In addition to exchanging the air, these fans are used to enable maintenance and repair operations in the tunnel. Current plans call for blocking each tunnel tube for one night per week in order to perform preventive maintenance work, thus enhancing the tunnel’s overall functionality and availability. During these hours, many people will be in the tunnel who require fresh air. “One of the major criteria for winning this bid was the fans’ ability to quickly switch between a wide-range of modes. TLT fans are among the best in the world in this regard,” said Andreas Kuhn, TLT’s project manager for the Gotthard Base Tunnel, about the selection of his company’s fans for this project."

Dec 1, 2016

By Claire C. Caruso, John M. Russo, Jennifer M. Schmit, Robert B. Dick, Edward M. Hitchcock

PURPOSE This report provides an integrative review of 52 recently published research reports that examine the associations between long working hours and illnesses, injuries, health behaviors, and performance. The report is restricted to a description of the findings and methods and is not intended as an exhaustive discussion of all important issues related to long working hours. Findings and methods are summarized as reported by the original authors, and the study methods are not critically evaluated for quality. SUMMARY In 16 of 22 studies addressing general health effects, overtime was associated with poorer perceived general health, increased injury rates, more illnesses, or increased mortality. One meta-analysis of long work hours suggested a possible weak relationship with preterm birth. Overtime was associated with unhealthy weight gain in two studies, increased alcohol use in two of three studies, increased smoking in one of two studies, and poorer neuropsychological test performance in one study. Some reports did not support this trend, finding no relationship between long work hours and leisure-time physical activity (two of three studies) and no relationship with drug abuse (one study). A pattern of deteriorating performance on psycho physiological tests as well as injuries while working long hours was observed across study findings, particularly with very long shifts and when 12-hour shifts combined with more than 40 hours of work a week. Four studies that focused on effects during extended shifts reported that the9thto 12th hours of work were associated with feelings of decreased alertness and increased fatigue, lower cognitive function, declines in vigilance on task measures, and increased injuries. Two studies examining physicians who worked very long shifts reported deterioration on various measures of cognitive performance. When 12-hour shifts combined with other work-related demands, a pattern of more adverse findings was detected across studies. Six studies examining 12-hour shifts combined with more than 40 hours of work per week reported increases in health complaints, deterioration in performance, or slower pace of work. Two studies com-paring 8- and 12-hour schedules during day and night shifts reported that 12-hour night shifts were associated with more physical fatigue, smoking, or alcohol use. Two studies examining start times for 12-hour shifts reported that decrements in alertness or more health complaints were associated with early 6:00 a.m. start times. One study examining 12-hour shifts in hot work environments reported a slower pace of work as compared with shorter shifts. Another study examining high workloads during 12-hour shifts showed increased discomfort and deterioration in performance as compared with shorter shifts. More definitive statements about differences between 8-hour and 12-hour shifts are difficult because of the inconsistencies in the types of work schedules examined across studies. Work schedules differed by the time of day (i.e., day, evening, night), fixed versus rotating schedules, speed of rotation, direction of rotation, number of hours worked per week, number of consecutive days worked, number of rest days, and number of weekends off. All of these factors could have interacted with overtime and influenced study results. Also, some studies did not report how many hours participants worked per week or other details about the work shifts, which complicated the assessment of their results. The many

Jan 4, 2004

By D. Diekman

Perlite is not a trade name but a generic term for naturally occurring siliceous volcanic rock. A distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands 5 to 20 times its original volume. This expansion is due to the presence of 2% to 6% combined water in the crude perlite rock. When quickly heated above 1600°F (871°C) crude perlite pops in a manner similar to popcorn. The combined water vaporizes and creates countless tiny bubbles in the heat softened glassy particles. It is these tiny glass sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite. The bulk densities of the expanded perlite generally range from 3 pounds per cubic foot (48 Kg M3) to 10 pounds per cubic foot (160 Kg H3).

Jan 1, 1985

By C. D. Litton

When methods to prevent the occurrence of fire in underground mines fail, the next line of defense is to rapidly and reliably detect the developing fire, so that subsequent evacuation and control procedures can be safely and successfully implemented. To provide this capability requires an understanding of the operational principles of different types of fire sensors, their merits as well as their limitations, and performance characteristics of the monitoring systems that control and process sensor data; an understanding of how fires develop and the different types of fires that can occur, along with their characteristics and the hazards they present; an understanding of the impact of the mine environment and routine mining activities, not only in terms of these effects on fire sensors but also in terms of the impact of mine ventilation and mine geometry on fire growth, fire characteristics and the detection process. All of these factors are components of the technology of fire detection, and when insufficient knowledge of any of these components exists, the ability to implement adequate mine fire detection systems is diminished. Within the last decade, significant advances have been made in fire detection technology applicable to underground mines. These advances include not only the development of improved sensors and better monitoring systems, but also an expanded understanding of how to deploy sensors, set sensor alert/alarm levels, account for ventilation effects, etc. In addition, there has been an increase in our knowledge of the types of fires that occur, the types of combustibles involved, characteristic times for fire growth and development, the levels of heat, smoke and gas that are produced and the hazards that result. It is the intent of this paper to provide not an overview of current mine fire detection technology and, also, to present data obtained for some smoke sensors that have potential for use in underground mines. The paper will also discuss the data, information and resources that are currently available and seek to identify those areas most in need of further research and development.

Jan 1, 2011

By D. C. Torre

The coal mining industry has long recognized the need for a system capable of hauling mined coal from the face in a continuous flow. More than 30 years ago, successfully operating continuous haulage systems were first placed in the field. There were a few individually successful applications. However, the truly successful use of such systems really only began in the early seventies. Today, a variety of systems are available from a number of manufacturers. Even so, continuous haulage has not achieved the acceptance and application it would seem to have earned. There is a need for more productive, cost-effective, and safer methods of hauling coal from the face. There is also a need to speed up development for longwall operations. And continuous mining is not really "continuous" unless it is supported by a reliable continuous haulage system. Despite all this, most of the coal producers have failed to exploit the successful continuous haulage systems offered by several manufacturers. In the 1970s, many of the top coal producers tried a continuous haulage system but gave up on it and on the concept. In some cases, major coal companies had systems operating successfully in one mine, or even one division. But their use did not spread to others of their mines or divisions. Frequently, their use was eventually abandoned, even in mines where it had been successful.

Jan 1, 1990

By Suzanne Paradis

Geographic distribution ? Deposit economics ? Temporal distribution ? Tectonic settings ? Basin architecture ? Morphology ? Ore-fluid chemistries Key exploration criteria

May 1, 2006

By Quemard D, Troncoso J

The Gordonstone Project with a capital cost in excess of $500 million will become the largest underground coal mine in Australia. The project development decision was taken on 31 July, 1990 and at 31 May, 1991 construction was approximately 35 per cent complete. The first train of processed product coal will be railed to Gladstone during December 1992. The general theme of this paper therefore will address the planning and development processes at Gordonstone particularly the interrelatedness of technical, production, construction and environmental disciplines to ensure success during operations.

Jan 1, 1991

SASOL Synthetic Fuels has recently completed the design of sampling systems for raw and blended coal feeding the gasifiers at Secunda, South Africa. The new systems will replace manual, stopped belt sampling and have been designed to achieve specific accuracy targets on a daily basis. The sampling system is unusual in the coal industry in that the fines content (-5.5 mm nominal) of the coal is very critical and is to be determined with high accuracy.The sampling system was designed to meet carefully considered target accuracies using methods of modern sampling theory. The heterogeneity of the coal streams involved with respect to the critical analytes was determined by appropriate sampling and sample analysis. The statistical characterisation of the time variation of analytes in the process streams was based on variograms derived from on-line ash gauges. From this point, the design was completed using fundamental statistical sampling theory and some simulation studies. The paper discusses the development of the sampling system design in detail as well as the plans to use the data stream to provide timely alarms when the coal quality deviates from the target specification.

Jan 1, 2002