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By Carlos Álvarez, Sergio Sánchez, Michael Mains, Giuseppe Gaspari

Extensive record of tunnels excavated with SEM (sequential excavation method) in swelling grounds exists in literature: global experiences include successful tunnelling both through clayey and rock masses with time dependant deformation. However, TBM (tunnel boring machine) use in swelling conditions with high water pressures (EPB, earth pressure balance, machines or slurry shields) is much less documented, considering the lower expected impact due to the limited stress relief and operations under saturated conditions. This paper summarizes a number of studies conducted as part of the risk assessment and detailed design of a large diameter TBM tunnel in variable and challenging geological conditions. The tunnel alignment is driven through mixed face conditions including swelling soils and clayey soft rocks, prone to intense time-dependent deformations. The paper also describes the approach adopted for the design of pre-cast segmental lining subject to both swelling actions and high seismic loads, due to the regional active tectonic faults. The design of this lining included a detailed parametric study performed to handle the existing uncertainties related with ground characterization, potential deconnement and complex geological congurations.

Jun 23, 2024

By Yi Luo

This paper presents some of the results of a research on long-term subsidence over and near the chain pillar systems -the area available to long-term subsidence in longwall operations. Although the long-term subsidence in most longwall operation is insignificant, it does exist in some cases. For the cases where long-term subsidence is significant, it has been found that the development process can be expressed by an exponential decaying function. The stability factor of the chain pillar system and the potential for long-term subsidence are the two important factors that control the magnitude and development characteristics of the long-term subsidence process.

Jan 1, 1999

By K. W. Harris, K. A. Perry

Reserve depletion in Central Appalachia is continuously creating unique ground conditions for underground coal mines with many of these difficult environments directly attributable to multiple seam mining and/or deeper overburdens. While many empirical studies have been performed in an effort to improve understanding of these problems along with potentially improving safety and extraction, many of the difficulties encountered lie outside of the normal realm of expected behavior. This is often the case when mining in bump prone ground, where additional concerns are introduced and design buffers are warranted. The boundary element software LaModel was used to study three bump events in a deep-cover, multiple-seam reserve located in Harlan county in the Kentucky region of Central Appalachia. This region is notoriously bump prone due to significant areas of deep cover, the presence of strong to massive lithology (such as sandstone), and an extensive history of underground mining that increases the probability of multiple seam interactions. Multiple seam interactions are best understood with respect to site-specific parameters, including both the geological and geometrical components of interburden, overburden and mine workings. Initially, empirical-based approaches (ARMPS/AMSS) were used when attempting to back-analyze the bump events. However, it was recognized that a more detailed investigation was necessary to understand the fundamental causes/conditions associated with the bump events. Consequently, the LaModel study resulted in a mine-specific calibration method for the reserve. With this method in place, enhanced bump prediction throughout the reserve is expected, such that the stability, recovery and safety of future mining may be improved.

Jan 1, 2014

By S. Mathur

Polyacrylic acid (P AA) was evaluated as a selective flocculant for dolomite-apatite system. P AA of 4 million MW was found to flocculate both dolomite and apatite. However, their flocculation behavior was significantly different with 450,000 MW PAA which was the lowest molecular weight fraction capable of flocculation. In single mineral tests, at a dosage of 2kg/t 90% of dolomite and 35% of apatite flocculated. Selectivity was achieved in mixed mineral tests where apatite of 90% grade at 70% recovery level was obtained in the concentrate from a feed consisting of 80:20 mixture of apatite and dolomite. The dolomite rejection was about 75% which corresponds to 1% MgO in the concentrate.

Jan 1, 1995

By Brian Fulcher, John Eastlund, J. B. Copeland

Following the completion of the 7,600 m primary access tunnel by Kiewit/Parsons Brinckerhoff (K/PB) in April 1997, an exploratory East-West Cross Drift Tunnel was constructed at the Yucca Mountain Project over the proposed future repository block for high level nuclear wastes. The 2,681 m (8,796 LF) East-West Cross Drift Tunnel was excavated through volcanic tuffs having zones of incompetent rock using a re-built Robbins 5.000 m (16’-5”) hardrock TBM with a special arrangement of supporting equipment. Details of the unusual site and contract conditions will be discussed as well as with the unique tunnel equipment specified by the Owner. This portion of the Yucca Mountain project required eight months to complete.

Jan 1, 1999

By Guangyao Si, Ismet Canbulat, Xun Luo, Yi Duan

Routine analyses of seismicity and event locations are essential for coal burst risk management, especially in the presence of unfavorable and complex geology. In an Australian longwall coal mine, a small-scale seismic monitoring network was installed to monitor a section of a major dyke intersected by the roadway, which was classified as a coal burst prone zone. The Deep Convolutional Neural Network (DCNN) technique was adopted for automatically discriminating seismic events to assess seismicity in this zone. The discriminated seismic events were located with the Shortest Path Method based on the Boundary Discretization Scheme (BDS-SPM) for temporal-spatial seismic event distribution analysis. The results demonstrate that the seismic events are discriminated with an average accuracy of 94%. Moreover, the seismic events are more accurately located using the BDS-SPM with a 3D heterogeneous velocity model compared with results obtained with a homogeneous velocity model. The temporal and spatial variances in seismic activities identify that the rock fractures in the dyke zone are closely related to the longwall mining process and a local dyke has a controlling influence on the stress concentration in its vicinity.

Apr 26, 2022

By S. G. Britton

Microcomputer analysis has long been a technique for engineering professionals to improve the theoretical and practical design of continuous mining systems. Such work has been typically composed of modeling observed events and then introducing a variety of known elements with predicted results to compare against the results of the model. Programs written in BASIC, Cobol, Fortran, or other language dominated such efforts. These programs have taken years to develop and prove out. This paper explores a new management tool used at TMC on a daily basis to track and improve continuous mining systems through the use of microcomputers and Lotus 1-2-3 software. By analyzing data provided by section foreman, shift foreman, and maintenance personnel against predetermined goals, new production targets are developed, weaknesses in the current mining systems are identified, and the results of changes are measured. The results of this system on the productive output of TMC systems are on the order of ten percent improvement.

Jan 1, 1991

By G. G. Marino, Z. R. Widup

Marino Engineering Associates, Inc. (MEA) was asked to determine the effects of mining beneath a proposed roadway structure. In order to determine the subsidence potential and the magnitude of the mine stabilization costs it is important to know whether underground mining is present, and if so, to what a real extent. The site investigated had the potential to have mining in three different coal seams. To determine where mining was present MEAÕs borehole radar system was used. In summary, the borehole radar subsurface investigation validated that the available mine map in the most shallow coal seam was fairly accurate despite its age (1888), found no mining in the underlying coal seam and detected an area of unknown mining at a depth of about 300 ft in the lowest coal seam which was verified by subsequent drilling.

Jan 1, 2004

By Joseph Moses Botbol

Two methods are developed whereby; (1) mineralogic data can be arranged in order of typicality, and (2) mineralogic data external to a model can be compared with the model and the degrees of association computed. Thirty arbitrarily selected base metal mining districts in the conterminous United States were classified as copper, lead, or zinc districts on the basis of tonnage of the major base metal produced. For each of the copper, lead, and zinc districts binary-occurrence distributions were compiled for primary (unoxidized) and secondary (oxidized) minerals. Primary and secondary minerals were then arranged in order of decreasing typicality. Model copper districts are most typified by primary chalcopyrite, pyrite, and secondary malachite. Model lead districts are most typified by primary galena, quartz, pyrite, sphalerite, and secondary anglesite and cerargyrite. Model zinc districts are most typified by primary sphalerite, galena, pyrite, quartz, and secondary smithsonite and cerus-site. The Park City district was removed from the model and its primary and secondary mineralogy was compared with the model copper, lead, and zinc districts. The primary mineralogy of the Park City district is about equally associated with the model copper and lead districts, but the secondary mineralogy is much more akin to the model copper districts. Thus, with respect to the model data, the geochemical target presented by the Park City district resembles a copper district more closely than a lead district.

Jan 1, 1969

By Robert B. Scott

The Dents Run Demonstration Project near Morgantown, West Virginia, was a cooperative venture involving the U.S. Environmental Protection Agency (EPA), the Water Resources Division (WRD)(1) of the West Virginia Department of Natural Resources (DNR), and the Christopher Division of the Consolidation Coal Company (CONSOL). The object of this project was to demonstrate pollution control methods and to clean up a 37.8 sq km (14.6 sq mi) watershed severely polluted by coal mine drainage. A study entitled, "Water Infiltration Control to Achieve Mine Water Pollution Control" (EPA-R-2-73-142),(2) was conducted by the Cyrus Wm. Rico Division of NUS Corporation for the grantee to determine the feasibility of utilizing remedial techniques to improve the Dents Run water¬shed. This study showed that the Dents Run watershed was discharging as much as 6,870 kg/day (15,100 lb/day) of acid; 1620 kg/day (3,560 lb/day) of iron 17,250 kg/day (38,000 lb/day) of sulfates; and 29,500 kg/day (64,900 lb/day) of total dissolved solids into the Monongahela River near Morgantown, West Virginia. This pollution was caused by the combination of borehole pump discharges from active underground mines, runoff from abandoned strip mines, and runoff from refuse dumps.

Jan 1, 1977

By William P. Blacutt

This paper describes the strategy, the struggles, and the obstacles encountered during the last two years in the ongoing process to capitalize Vinto. The effort involves the offering of a vertically integrated business package composed of the tin and antimony smelters along with the two principal tin mines of the country. Capitalization: Bolivia's Innovative Approach for Privatization, the Vinto Case provides a summary of hard-earned lessons. These experiences can be success- fully implemented in other nations committed to transforming their state natural resource sector.

Jan 1, 1998

By J. Herhold, S. Plaum

"Current and future operational processes in the mining and underground construction sector are under the influence of the prevalent competition and the acute necessity of optimization approaches concerning corporate and project processes. Besides general construction procedures, especially underground construction procedures and procedures in the field of deep shaft construction are high-profile. Those processes describe high technical challenges as well as increased requirements to occupational safety and health. Therefor an occupational safety management, which should be adjustable to the company itself and adaptable to all kinds of projects, shall be created. The creation of such an occupational safety management would lead to an economically optimized and safe (within the scope of OSH law) implementation of internal activities for the performance of construction services underground and in the field of deep shaft construction. With this approach the satisfaction of the high safety request as well as the demand for process optimization, as part of keeping the own competitiveness, will be satisfied successfully at once. PROJECT BACKGROUND Introduction The health and safety protection as well as occupational safety look back on a long historical development, which had brought more important sectors and developments during the last years, not only in Germany but also on the European and international level. The accident insurance protected by law has already been reported in 1884, which is astonishing early. The launch time point is strongly connected with the on-going economic development in the end of the 18th century, but above all this increased in the 19th century. The progress of occupational safety and especially the interest in the integration and the concentrated consideration of occupational safety and the health and safety protection in the company process is strongly visible during the 19th century and directly connected to the industrial revolution. [9] The industrial revolution and with that the development of work places lead to changing demands in the field occupational safety and health and safety protection. Insufficient security precautions caused problems in the industrial revolution, such as personnel and material losses as well as serious injuries and their consequences. These and the fundamental economic endeavours of the entrepreneurs lead therefore to the important step to develop an occupational safety system. [9] The prevailing basic ideas seize the insufficient security precaution of work places as well as the economical and profitable ideas of the entrepreneurs and bring them together. From this the necessary entrepreneur’s task comes into being and that is bringing the work conditions to the way that life and health of employees are not in danger. [9]"

Jan 1, 2017

By Kristin Hemlein

Mining project development, permitting, environmental regulatory and compliance issues in Uzbekistan and the CIS are every bit as complex as those in the western world. The vast array of environmental permitting, monitoring and reporting regulations for mine project development and operation in the CIS are based on existing Soviet environmental regulations and policies which have remained in place after these countries gained independence from the former Soviet Union. The approach to mine project permitting in the CIS differs from the western world. Similar pre- feasibility, baseline data collection, and environmental monitoring requirements allow the project proponent to coordinate preparation and submission of documentation to support project permitting for Uzbek regulatory requirements with environmental requirements imposed by financial institutions and western environmental compliance structures. Implementation of generally accepted western environmental best management controls and monitoring into mine design, construction, and operation will not, however, ensure automatic compliance with Uzbek environmental regulations. Uzbek environmental compliance requirements that differ from western requirements include: 1) development and maintenance of an environmental database constructed specifically to address annual, biannual and quarterly statistical reporting requirements for emissions of "environmental pollutants" from the facility into air, surface water, ground water and soil; 2) preparation and submittal of specific permits for water utilization, hazardous waste storage and disposal, landfill construction and operation, and stack emissions inventories; and 3) procurement of approvals from the Uzbekistan State Committee for Nature Protection (generally analogous to the US Environmental Protection Agency). This paper outlines and summarizes the regulatory requirements for mine site permitting and the procedures for environmental monitoring and reporting during mining operation in Uzbekistan and the CIS.

Jan 1, 1997

By Brendan Demich, Linda L. Chasko, Brendan Macdonald, Timothy J. Orr, Jessie J. Mechling, Cassandra Hoebbel, Jason Navoyski, William Helfrich, Jessica Cohen, Paul E. Schmidt, Jennica L. Bellanca

The National Institute for Occupational Safety and Health (NIOSH) in partnership with the Mine Safety and Health Administration (MSHA) developed VR Mine Rescue Training (VR-MRT). It is a training platform that allows mine rescue team members to explore virtual emergency scenarios collaboratively. Team members use a head-mounted display to visualize and interact together with equipment, hazards, and dynamic ventilation. All player actions are recorded and displayed for debriefing. Researchers at NIOSH demonstrated the training platform at various mine rescue competitions, including the International Mine Rescue Competition, and collected feedback. Participants’ responses were overwhelmingly positive. This paper describes the development of the software platform and the results of the usability surveys and interviews.

Jun 25, 2023

By J. Philip Bromberg

The 1977 Clean Air Act Amendments will have a large effect on the coal-fired segment of the electric utility industry. Since electric power generation constitutes by far the largest single use for coal, this legislation has the potential to greatly affect future patterns of coal utilization in the U.S.A. The inability to depend exclusively upon low sulfur coal as an exclusive mode of compliance with New Source Performance Standards may greatly lessen projected demands for low sulfur coal by eastern utility boilers. The requirements of the legislation is discussed with particular reference to the needs of the electric generating industry, along with the technologies available for complying with the Act.

Jan 1, 1978

By J. S. Heath

Many disputes related to environmental issues in mining are resolved through often-antagonistic negotiations in a regulatory context or through litigation. These approaches are certainly the best choices for resolving certain disputes. However, just as no single remediation technology is the right fit for every site, so no single dispute resolution process is the best choice for every situation. This paper introduces a range of dispute resolution alternatives (from collaborative decision making through mediation, arbitration, and litigation). Especially when money is tightest, cost-effective dispute resolution(and the outcomes that can accompany it) can have an impact on the bottom line.

Jan 1, 2000

Anomalous geologic or stress conditions ahead of the longwall face can cause great harm to both the individual miner and the mining operation as a whole. The U.S. Bureau of Mines has been developing seismic tomography techniques to image the panel ahead of the face. This paper presents the results of a field effort in which a 60-m (200-ft) segment of a longwall panel containing a fault zone was surveyed daily as the face approached. Stress distribution, geologic structure, and dynamic elastic properties within the panel were plotted and compared to static laboratory measurements. The surveys successfully imaged an anomalous stress concentration, likely influenced by the presence of the fault zone. The calculated dynamic physical properties generally agreed with laboratory measurements.

Jan 1, 1995

By Daniel B. Brimhall

The research presented here was initiated to investigate the role of atmospheric oxygen in the leaching of copper waste dumps. The problem of increasing the recovery rate of copper from these dumps is or great importance considering there are by conservative estimate in excess of fifteen billion pounds of copper located in dumps in the western United States. At this time, there is an increased interest in recovering copper from these dumps on a large scale. Large tonnages of low-grade material are being placed on the waste dumps of most copper mining operations in the western United States each day. The size of these dumps ranges from 5.5 million tons at Mineral Park, Arizona, to 4 billion tons at Kennecott's Utah operation (1). Leach solutions are recycled and contain ferrous and ferric sulfates. Large quantities of dissolved aluminum, magnesium and calcium salts may also be present. To this solution make up water is added to maintain the solution inventory and sulfuric acid is added for pH adjustment. Iron is introduced into the leach solution by the dissolution of the iron-containing sulfide and oxidized minerals present in the ore deposit. In addition to the iron from dump leaching, iron is also introduced during the precipitation process when the pregnant solution is passed over metallic scrap iron if cementation is used to reduce the copper in solution.

Jan 1, 1972

By Ma Fangyuan, Li Min, Xu Bing, Xian Yushuai, Zhao Tonglin

The study explored a new combination amine collector (XK-28) that can obtain better flotation index and defoaming rate for magnetic iron ore. A pure quartz mineral test indicates that dodecylamine, XK-I, or XK-II has good collection effect on quartz and their best flotation pH is in the range of 6–7. The experimental results of a combination collector (XK-I:XK-II = 2:8.) show that the separation effect for quartz and magnetite is better than that of a single collector. The single factor for actual mineral test shows that when the combined reagent is used as the collector, the best conditions are pH = 7, 90 g/t dosage, and XK-I:XK-II = 2:8, which is consistant with the pure mineral test. The difference for dodecylamine as a collector is that the optimal dodecylamine dosage is 60 g/t. Under the best conditions of actual ore test, dodecylamine and XK-28 are respectively used as the collector to compare the flotation indexes. Study results indicate the magnetite grade using XK-28 as the collector is higher by 3.02% than that of using dodecylamine, recovery is increased by 1.92% over that of using dodecylamine. Based on the measurement results of zeta potential, uses of XK-28 can slightly increase the zeta potential difference of quartz and magnetite to enhance the flotation effect. The mechanism of action between the XK-28 collector and the actual ore from the Gongchangling plant is physical adsorption, and this adsorption also has hydrogen bond formation. Contact angle results shows that XK-28 improves the hydrophobicity of quartz better than dodecylamine. Compared with dodecylamine, XK-28 is more sparsely arranged on the surface of the foam. The foam produced by the XK-28 collector has better air permeability and it is more likely to merge and disappear with bubbles.

Jul 21, 2021

By R. V. Ramani

Minerals, together with agricultural and forestry products, are the primary source of wealth produced in the United States. Although the production of minerals requires only a small fraction of the state's total land surface, as compared with either agriculture or forestry (Table 1), mining activities generally are much more disruptive to the land surface, and rehabilitation is more complex and costly. The past 10 to 15 years have witnessed a sharp increase in mineral exploration and mining, particularly coal mining, which has brought with it an increase in conflict over land use and an increase in negotiations for purposes of mineral prospecting and mining. The general increase in the production and consumption of coal and the particular increase in the percentage of coal extracted by surface mining methods coupled with a growing nationwide environmental consciousness have created increased public concern and in some cases outrage over mining activities. Although there is ample evidence to indicate that it is possible to plan for and design mining activities in such a way that they are compatible with other activities and can thus be made a part of a sequential land-use plan, there is a general lack of knowledge regarding the importance of mining as the provider of basic and essential raw materials to supply society's constantly expanding and increasing mineral needs. This lack of knowledge extends to such matters as land and mineral rights negotiations, the character of mineral deposits and minerals, mineral economics, and land-use planning.

Jan 1, 1977