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The theme of the 2012 North American Tunneling conference (NAT) was ?Tunneling: Driving Value.? This theme best reflects where the tunneling and underground construction industry is to-day. Major advances that have been made in technologies have provided tremendous improvements in productivity, which, in turn, have allowed the industry to deliver more cost-effective and less disruptive solutions to the nation?s infrastructure needs. Despite a weak economy, domestically and globally, cities and states continue to spend billions on infrastructure improvements. For the underground construction industry, that means more transportation and water, wastewater, storm water projects and other underground structures. And, for each project completed, underground construction and tunneling technology grows. The NAT conference, put on by the Underground Construction Association (UCA) of SME, provides an outlet for technology transfers among professionals. This year?s conference, held in Indianapolis, IN June 24-27, attracted 918 attendees, up from 803 at the last NAT in 2010. The accompanying exhibit also featured 116 exhibitors occupying 140 booths. That was up from 108 booths in 2010. So, the meeting continues to grow as underground construction professionals throughout the world seek to learn from their peers.

Jan 1, 2012

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

Jan 1, 2007

Using mines in Canada, Boart Longyear, a leading provider of drilling services and products, has put its Stage 3 Coring Bit to the test and each time the bit has passed the test with great success. After more than a year in the field at a major mine operation in Sudbury, Canada, the Stage3 coring bit broke life records to become recognized as the most productive design in the industry. In addition to the proven advantage seen in regular bit life increases of as much as 300 percent in some cases, the design is quickly being recognized for its cost-saving operational impact. In Sudbury, the mine operation realized actual cash savings of more than C$45,000 within an eight-month period by making the switch to Stage3 bits. For years, the Sudbury Basin team has relied on the Alpha Extended Crown bit with the Express Waterway geometry option, ordering approximately 500 units per year. This 07 COM ECEX configuration performed well in medium-hard, non-abrasive to ultra-hard, non-abrasive formations with an average bit life of 150 m (490 ft). While satisfied with the performance of the Alpha Ex-tended Crown, the team agreed to put the new Alpha Stage3 to the test. Boart Longyear?s field engineers supplied five drill sites with Alpha Stage3 bits in a 07 COM configuration. After thoroughly testing the Stage3, the results were clear. Even with the well-known performance and versatility offered by the previously preferred configuration, the Stage3 set a new standard of bit performance. The new bit maintained its cutting edge for up to three times longer than the Alpha Extended Crown, a significant performance increase when compared to the 07 COM ECEX.

Jan 1, 2009

By Tony S. Calayag

Throughout the mining industry today, new bearing materials - ZA* high-performance zinc-aluminum alloys - are reducing costs of maintaining and rebuilding a wide range of equipment. As replacements for bronze bearings, installed in original equipment at the plant or during maintenance and repair operations in the field, the zinc alloys frequently provide better or equal performance at lower cost. The ZA Alloys The ZA alloys are a family of three high-performance zinc-aluminum alloys that compete in cost and performance with cast iron aluminum and bronze. The growing number and uses testifies to the versatility of these alloys and is encouraging their consideration in a wider range of applications. The ZA alloys are referred to as ZA-8, ZA-12, and ZA-27, the numbers corresponding approximately to the percentage of aluminum each alloy contains. ZA-8 is a permanent-mold casting alloy and is usually selected for decorative purposes; ZA-12 provides both performance and cosmetic benefits; ZA-27 offers the greatest functional strength. The term high performance ZA alloys distinguishes them and their improved engineering properties from traditional zinc die casting alloys. Maintenance Savings At its mine in Timmins, Ontario, Kidd Creek Mines Ltd. operates over 40 Joy VCR- 150 crawler-mounted air-powered rock drills. Most of the drill components undergo severe stress as the drill batters through the under-ground rock. As the components wear, the drill bits wobble; when the wobble becomes excessive, the drills are rebuilt. In the gear train, which rotates the drill steel, there are three planetary gears with - historically - bronze bushings. Since the planetary gear bushings are wear items, they are routinely replaced during overhaul. The bronze planetary gear bushings (three bushings per assembly) were replaced up to five times annually. With 43 drills in use, bushing consumption approached 600 per year. At the manufacturer's replacement part cost, the 600 bushings and gears would cost more than $20,000 a year. Even though a major saving was achieved by having the bronze bushings manufactured locally, the 600-unit annual usage provided ample incentive to investigate other ways of lengthening drill life and reducing the part costs. One approach was to consider using a bushing material that offered good bearing properties, but was lower in cost. About three years ago, ZA-12 zinc-aluminum casting alloy, costing less than half as much as bronze, was evaluated and selected for testing. One hundred ZA bushings were manufactured and placed in service as the drills came in for rebuilding. At the next rebuild the "drill doctor" (drill maintenance mechanic) noticed that, although the bronze bushings were completely destroyed, on occasion the zinc alloy bushings were not. In addition, he noted that some of the ZA bushings showed less wear than the bronze bushings. Because the bushings were changed routinely during each overhaul, the actual operating life of each bushing was not determinable. Therefore, it was not possible to statistically compare the life of the ZA bushing against the bronze. However, the desired life of the part was from overhaul to overhaul. So the ZA alloy obviously met the objective, giving equal or better life than bronze at a significantly lower price. Based on the favorable results of the testing under actual operating conditions, Kidd Creek maintenance personnel decided to switch permanently to the ZA bushings for rebuilding the VCR-150 rock drills. Original Equipment Application As one of the leading companies marketing the ZA alloys, as well as a zinc -copper-silver mining company, Kidd Creek is interested in developing applications for the alloys by original equipment manufacturers such as joy Manufacturing. Kidd Creek marketing representatives provided joy with information on the Timmins mine tests, along with ZA-12 bushings for evaluation and testing. Based on this information, joy installed ZA bushings in 12 new VCR-150 units and delivered them to customers for use in such areas as granite quarries and copper, lead, zinc, and limestone mines. During the following year, joy engineers closely monitored repair reports to verify the performance of the ZA part. The engineers' findings convinced them of the advantages of ZA-12. As a result, joy now uses ZA-12 bushings in the manufacture of its VCR-150 air tools. Advantages for Casters and Users In the foundry, the new alloys have proved their castability and profit potential in sand and metal permanent-mold processes, as well as the new graphite permanent-mold gravity casting process. The energysaving, pollution-free and ease-of-machining benefits they offer are important to all of these processes. Most recently, the high-performance alloys entered the arena of cold-chamber die casting, where they provide properties beyond those of

Jan 7, 1983

By Shuangchun Yang, Le Tong, Ronggui Fan, Cunlei Li

Acid mine drainage (AMD) is difficult to treat due to its physicochemical characteristics, such as high pH and high heavy metal concentrations, so it causes great harm to the environment and human health. If acid mine drainage is discharged arbitrarily without treatment, it will lead to a series of environmental problems and cause long-term environmental pollution. In this paper, the source and hazards of acid mine drainage are introduced in detail. And the principle, the mechanism, the application, and basic information of the current primary technology of the treatment for acid mine drainage are comprehensively introduced and summarized. The summarized treatment technologies for acid mine drainage mainly include neutralization, sulfidization, constructed wetland method, adsorption method, microbiological method, ion exchange method, membrane technology, and microbial fuel cell technology. Also, the primary technology of treatment for acid mine drainage is systematically compared and evaluated. Moreover, some suggestions on the development direction of water treatment technology in the future are put forward. This paper provides a scientific reference for scientific and technical works to treat acid mine drainage.

Sep 4, 2020

Amid some of the worst economic conditions that the mining industry has been faced with in more than a decade, the mood among the large crowd at the 114th Annual Northwest Mining Association?s annual meeting was surprisingly upbeat. More than 2,200 attendees showed up at John Asuaga?s Golden Nugget Casino in Reno, NV for the conference held Dec. 1-5. And more than 200 companies exhibited in 240 spaces, including SME and the Minerals Information Institute. The number of attendees and exhibitors were the most for the conference in more than 10 years. The conference was held in Reno/Sparks for just the second time in its illustrious history but began under the cloud of global financial turmoil. Prior to, and during the conference, the industry news headlines were grim, to say the least. An alarming number of mine plans and expansions had been put on hold; hundreds of miners across the United States had been or were in the process of being laid off; commodity prices were falling and some of the biggest mergers in the industry fell through while miners around the world put the brakes on to take a wait-and-see approach. It was a painful time for many, but the downsizing actions taken by many mining companies was exactly what needed to happen, according to Industry Outlook Luncheon featured speaker Frederick Sturm. He is the executive vice president and chief investment strategist and member of Mackenzie?s Investment team. He has earned a reputation as one of Canada?s leading investors in natural-based companies and he also manages the Ivy Global Natural Resource Fund in the United States Sturm said that the mining industry has fallen hard and that he expects it to bounce back quickly, before falling hard again. In these tough times, he said, the companies that have pulled back on production early are doing the right thing in the long run.

Jan 1, 2009

By Allison

During the 1980’s, laboratories opened throughout the United States to serve the analysis needs of a rapidly growing asbestos abatement industry. The samples analyzed were either collected during the abatement of known asbestos-containing materials or were suspect asbestos-containing construction materials. Many asbestos analysts received minimal training and used analytical protocols that were industry specific. False positives (reporting a sample as containing asbestos when none is present) went unnoticed or had minor repercussions. The mindset of the industry was to err on the conservative side – it would be better to identify a non-asbestos fiber as asbestos than visa versa. With growing public awareness of the health hazards of asbestos, other materials began to be tested for asbestos content. Rock and ores began to be tested for naturally occurring asbestos by these laboratories using the same protocols or an in-house protocol. Analysts were given no additional training and accreditation, in most cases, it was not required. With no consistency in sample collection, testing protocol or expertise in analysis, significant discrepancies in final results can be expected. If we further complicate this scenario with misidentification of naturally occurring look-a-likes for asbestos, expensive false positives are likely. To avoid the repercussions of misidentification of naturally occurring chrysotile asbestos from look-a-like fibers in rock and ores, correct sampling and analysis protocols with more stringent scientific diagnostic criteria are needed.

Jan 1, 2005

By M. J. Farrell

The threat of global warming and its prominent position in public discussion and political debate requires all industry to take stock of its contribution to rising atmospheric concentration of greenhouse gases. For the primary metals industry, the first step must be to identify the pattern and range of emissions at each step in the production chain. Only then can the industry assess the economic consequences of the penalties on emissions that will be imposed by governments and regulators and devise cost-effective plans to avoid or mitigate such penalties. While some work has been done to estimate carbon dioxide (CO2) emissions using Life Cycle Inventory analysis, this approach is less useful than site-by-site emissions estimates. It is the level of specific emissions at each site that will ultimately deter-mine carbon taxation liabilities and participation in emissions trading schemes. Most mining companies have moved with the times to issue sustainability reports for their operations. But in the absence of any standardized reporting format, it is difficult to make useful comparisons between even the best-reported producers on a like-with-like basis. For this reason, Minecost.com modeled the use of fuels and energy used in mining, milling, shipping and metallurgical treatment to cover ?cradle-to-gate? emissions of greenhouse gases resulting from the production of the major base metals copper, zinc, lead and nickel. Greenhouse gas emissions ? overwhelmingly carbon dioxide ? are associated with the consumption of energy at every step in the production chain, from exploration through mining to the production of refined metal. Producers of primary metal employ diverse technologies to mine, mill, smelt and refine several different types of ore. Every orebody has its own special characteristics. In addition, most base metals are produced in concentrate that must be transported to smelters, with con-sequent emissions consequences.

Jan 1, 2009

By Hans Hamrin

Three drill-blast cycles of 3.1 m advance achieved in one working shift of 7.5 hours at the Holsfjorden Tunnel project in Norway. The tunnel, 5235 m long, with a cross section of 8.6 m2, was completed several months ahead of schedule. This remarkable performance was achieved by a crew of 16 men, using machines specially designed for small tunnel excavation. The integration of drilling and charging into one unit, mucking and transport in another, reduced non-productive time considerably. The average cycle time of 140 min made it possible to complete three rounds in one 7.5 hours shift.

Jan 1, 1987

By Andrew Kaczmarek

The mining industry is enjoying a much needed and long awaited increase in demand for natural resources. However, consolidations in the mining and mining service industries, along with a generational departure of experienced industry professionals, is challenging today’s mining companies. These challenges are not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies. They oftentimes lack for operating properties to draw experienced professionals from. Also, juniors have to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This article discusses some strategies developed by Anatolia Minerals Development (Anatolia) in developing its Çöpler gold project in central Turkey.

Jan 1, 2006

By Congling Shi, Marek Borowski, Yue Wang, Jianwei Cheng, Xixi Zhang, Xuan Xu

As the first barrier to prevent accidents caused by explosions in underground coal mines, the integrity and stability of mine seals have great effects on mine workers’ lives and underground production safety. In this paper, the mechanical responding performance of typical mine seals under the impact load are studied by using numerical simulation method. By such simulation studies, the safety of different seals subjected to the explosion load is evaluated. Seals’stability are also investigated under effects caused by various influence factors including thickness of mine seal, cutting depth into surrounding rocks, rock type, and the roof-tofloor convergence under given the explosion load. The research results can provide theoretical basis and reasonable improvements for mine seal’s construction practices for improving its anti-explosion performance.

By Congling Shi, Marek Borowski, Yue Wang, Jianwei Cheng, Xixi Zhang, Xuan Xu

As the first barrier to prevent accidents caused by explosions in underground coal mines, the integrity and stability of mine seals have great effects on mine workers’ lives and underground production safety. In this paper, the mechanical responding performance of typical mine seals under the impact load are studied by using numerical simulation method. By such simulation studies, the safety of different seals subjected to the explosion load is evaluated. Seals’stability are also investigated under effects caused by various influence factors including thickness of mine seal, cutting depth into surrounding rocks, rock type, and the roof-tofloor convergence under given the explosion load. The research results can provide theoretical basis and reasonable improvements for mine seal’s construction practices for improving its anti-explosion performance.

By John McDonald, Peter C. Raleigh, Christopher Dishlip

This paper will discuss how the construction management team and the contractor working together on the City of Los Angeles, North East Interceptor Sewer project, managed information on a daily basis. Data was synthesized from various sources including: inspection, survey, instrumentation, laboratory and the tunnel boring machine data logger systems to produce state-of-the-art reports and graphics which will become industry standard. Special emphasis is placed on how the data is managed and interpreted in a clear and objective manner, permitting the tunneling processes to be carefully monitored and suggesting appropriate action to be taken by the construction management team and contractor.

Jan 1, 2005

By Verya Nasri, Scott Thorburn

The City of Toronto and the Toronto Transit Commission (TTC) have conducted an Individual Environmental Assessment (EA) for a 6.2 km, 4-station underground extension of the Spadina Subway from Downsview Station to Steeles Avenue. This Environmental Assessment Study was performed in three phases including routes and general station locations, alignments and station concepts and detailed assessment of the effects of the undertaking. URS Canada Inc. has led the consultant team for this Study. The anticipated total duration of the project is approximately 6 years and its estimated total cost is about $1.4 billion. This paper presents the planning process of the project, the environmental and engineering challenges, and the measures taken to address them.

Jan 1, 2007

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By George K. Schenck

INTRODUCTION Recent advances in high-pressure water jet technology can be effectively employed in mining and tunneling. The new equipment is based on available industrial hardware such as pumps, nozzles, and rotary swivels and seals, and is compatible with present mining and tunneling techniques. Principal advantages of water-jet assisted cutting relative to standard cutting are higher production rates, lower dust levels, and reduced fines. When used on rock and coal miners, water jets mean that relatively smaller and cheaper machines can be purchased. If properly applied, the combined effect is lower cost and significantly improved health and safety. While commercial use of high-pressure water blast cutting and extraction of rock (and concrete) already has a firm foothold in Europe, application of this new technique is just beginning in America. This paper begins with current American applications of high-pressure water jets for drills, for slotting and channeling machines, and then discusses the emerging technology for initiating rock failure in conjunction with drag bits on coal plows, continuous miners and boom-type miners (roadheaders). The focus of this paper is use of high-pressure water jets for cutting rock. High-pressure water jet cutting utilizes water above 70 MPa and currently reaches to 300 MPa and above. Some informatfon is included on low pressure "wethead" coal shearers and boom miners with water pressure to about 15 MPa.

Jan 1, 1983

By Atta Ur Rehman, Kwame Awuah-Offei

"Information diffusion potential of a social media user affects how quickly information about a mineral project can diffuse through that user. If management can use social media and network analysis in community engagement programs to understand how fast and how far information will diffuse to communities and followers of particular social media users, it can selectively focus on the most influential users. This article proposes a method to examine the information diffusion potential of social media accounts. The work uses Gephi, an open source software, to extract and analyze data from different Twitter handles to predict their information diffusion potential. The work uses case studies of real Twitter users (e.g. mining news organizations and bloggers) associated with mining to illustrate the approach. The case study results show that there are significant disparities in information diffusion potential that will demand selective attention. This research will help mines develop effective social media engagement strategies.The mineral industry provides raw material for industrial activity to support society (Martens and Rattmann, 2001). Mines have changed from conventional mining practices to sustainable ones because of the negative impacts of mining in the past and increased public awareness (Wang et al., 2016). The concept of sustainable mining is getting mature, as stakeholders (e.g., governments, investors and host communities) are getting more involved in mining projects (World Economic Forum, 2014). The failure of mining companies to address the demands of these stakeholders might result in the failure to acquire a social license to operate (SLO) (Thomson and Boutilier, 2011). The SLO, if granted, is mutually beneficial to all stakeholders. Mines prefer being granted SLO and keeping it to avoid any kind of social unrest due to their operation (Prno, 2013; Moffat and Zhang, 2014). Mining communities can grant different levels of SLO ranging from withholding SLO to psychologically identifying with the project (Joyce and Thomson, 2000; Thomson and Boutilier, 2011).Most of the previous work to understand community perceptions and SLO in mining is generally qualitative (ICMM, 2012a; Thomson and Boutilier, 2011; Prno, 2013; Moffat and Zhang, 2014; IFC, 2014). In particular, there is limited work on how community perceptions change over time due to information diffusion (Boateng and Awuah-Offei, 2017). However, SLO changes with respect to time (Yates and Horvath, 2013), which can result in risks that are not easy to predict. Mine managers and engineers have a desire to understand these changes so as to mitigate these risks (Que and Awuah-Offei, 2014; Que et al., 2015)."

Jan 4, 2018

By Richard E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on developing the tools needed to mechanize a mining operation with a reasonable expectation of success. Mechanical mining entered the 1990s with new machines, new operating methods and new ideas for the future. Mechanical mining can provide higher production, increase safety, reduce roof support requirements, create smoother openings for better ventilation, substitute continuous production for cyclical drill-and-blast procedures, and create opportunities for automatic and teleoperated control. The full promise of this important technology still lies ahead. Obstacles include: • Long-term production prediction: Mechanical systems have a high capital cost. Although recouped by lower operating costs, the tradeoffs are not always clear to mine operators. • Cutting tools for hard rock: Rock of more than 103.4 MPa (15,000 psi) cannot be cut by flexible mining machines. • Machine designs: Many machines cannot convert the required power into rock cutting capability. • Engineering: Better use of the machines in the mine is needed.

Jan 1, 1994

By Michael Murphy, Gamal Rashed, Brent Slaker

Many underground stone mines in the United States operate on multiple mining levels. The effects of interburden thickness, pillar offset between mining levels at various depths of cover, and in situ stress conditions are poorly understood. Pillar offset is the degree to which pillars are not columnized or stacked. In this study, calibrated numerical models are used to examine limestone pillar stability in these conditions. Also, the critical interburden thickness required to minimize the interaction between mining levels is explored. The model results show that there is interaction between numerous factors that control the stability of stone pillars in multiple-level conditions. The highest degree of local pillar instability occurs when pillar overlap ranges between 10 and 70 percent. The highest degree of stability occurs when pillars are stacked.

Jan 1, 2023

By Andrew B. Cecala, Emily J. Haas, Jay F. Colinet

A sociotechnical system (STS) creates a framework that allows an examination of how social and technical factors affect organizational outcomes within a specific environmental context. STS has been rigorously studied with a primary research focus addressing worker-technology interactions. Although these interactions are important, the social processes and interactions that occur whenever any technical or environmental change is introduced into the system have been undervalued. If social processes are better understood, mining organizations could efficiently prepare and stabilize for such changes. With this goal in mind, we sought to extend STS theory through applying principles of meta-design to analyze the results of two case study interventions. Specifically, we studied the impact of an unregulated dust control technology (the Helmet-CAM) and a regulated dust control technology (the Continuous Personal Dust Monitor) on factors within an STS including employees’ knowledge of, communication about, and use of technology to mitigate respirable dust sources. The results are presented in a way that first, addresses the overarching principles of meta-design STS including organizational participation, flexibility, and communication and second, examines how technology implementation processes differ when the organization is complying with a formal, higher-level requirement. Results show that a prominent focus on the social factors within an STS framework could help reduce unpredictability on the technical side and may improve communication within the system to help reduce adoption time, especially if and when accompanying a new, formal work process.