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By D. S. Yantek, R. J. Matetic, A. K. Smith, E. D. Thimons, J. Srednicki

In a 2007 report to the U.S. Congress, the Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) stated that built-in-place refuge alternatives (BIP RAs) provide significant advantages over mobile refuge alternatives. At present, the requirement to locate refuge alternatives within 305 m (1,000 ft) of working faces makes BIP RAs impractical in most coal mines. BIP RAs would be practical if three issues are addressed: (1) allowing BIP RAs to be located at greater distances from the working face, (2) developing a reliable process for the design and approval of BIP RA stoppings that meet the 0.1-MPa (15-psi) design criteria, and (3) developing systems that reliably deliver breathable air to the refuge alternative. In 2015, NIOSH OMSHR conducted a study of these three issues and issued a report. In the report, justification was provided for allowing the placement of BIP RAs at greater distances from the working face than the currently mandated 305 m (1,000 ft), guidelines were developed that could be used by industry when submitting BIP RA stopping design applications for approval which are patterned after the Mine Safety and Health Administration guidelines for coal mine seal design applications, and insights were provided into options for providing a reliable supply of clean, breathable air to BIP RAs. This paper presents a summary of the study’s findings and also addresses issues discovered during the building and designing of a BIP RA that OMSHR researchers constructed in NIOSH’s Experimental Coal Mine in Pittsburgh to research the testing and improving of BIP RAs. These issues include several issues related to the delivery, distribution and exhaust of ventilation air to the BIP RA and some general construction issues that require further investigation.

Jan 1, 2016

By C. A. Oestreicher

For sulfide minerals, the presence of dissolved oxygen in the water phase is an influencing factor for separation by flotation. Klassen and Mokrousov(I:217l distinguish three stages of oxygen adsorption; namely, reversible adsorption, activated adsorption and, finally, surface oxidation. While contraversial, limited adsorption of oxygen is believed to improve the interfacial reactivity between collector and mineral. Intensive surface oxidation of sulfide minerals usually results in unsatisfactory flotation with collectors of the xanthate type. The influence of dissolved oxygen in the water phase has received consideration for sphalerite, galena, chalcopyrite, arsenopyrite, chalcocite, and covellite(2,3,4,5,6). However, the nature of surface oxidation products of sulfide minerals has received very limited investigation(6,7). Lightly oxidized galena promotes the adsorptive reaction of surfactant (xanthate or dixanthogen). Tolun and Kitchener(8) state that limited interaction occurs between galena and xanthate under relatively reducing conditions. And, that exposure to oxygen raises the electrochemical potential of the galena to that required for reaction with xanthate or dixanthogen. In the latter condition, the galena has an "effective flotation surface". On the other hand, intensive oxidation of galena reduces the chemical reaction with xanthate collectors (9) . Complete flotation with xanthate-type surfactants with increasing oxygen content in the water phase has been determined to have the following sulfide mineral sequence(3): galena, pyrite, sphalerite, chalcopyrite, pyrrhotite and arseno-pyrite. The work of Cusack(4) suggests that some threshold amount of oxygen is necessary for flotation to occur, but heavy oxidation hinders flotation with xanthates. According to Tolun and Kitchener(8) catalytic oxidation of xanthate to dixanthogen occurs. From infrared studies, Poling and Leja(IO,II) found that in the absence of oxygen in solution, xanthate ions do not adsorb either on

Jan 1, 1972

By Jürgen Kretschmann

According to the model of product life cycles, the global coal mining industry is in the stagnation phase. The coal demand of the main consumer, China, has peaked in 2013 and is slowly declining. The Norwegian sovereign wealth fund, the world’s largest, has excluded coal-related companies for ethical reasons. Important players like the UN or the EU have already begun to describe pathways towards decarbonization. Increasing competition between coal mining companies and the mining regions can be expected worldwide if companies want to keep their positions on the global and national coal markets. Companies will focus on the best deposits. European countries like France, Spain, or Germany are only forerunners of this development—their centuries of coal production have been finished. The concept of sustainable development (SD) is fundamentally based on a model of progress where ecological, economic, and social dimensions should be developed equally and positively. But without the idea of competition, the concept of SD is incomplete. Questions arise, such as how can SD be realized on stagnating or declining markets without guarantees for companies “to live forever”? How can SD be a corporate goal in a phase of decline? How can declining mining regions sustainably progress into a better future? The German hard coal mining industry’s lifecycle has ended in 2018 after 60 years of stagnation and decline. As of 2019, all hard coal consumed in Germany will be imported, especially from Colombia, Russia, and South Africa. What has been done in Germany to handle the coal decline in a sustainable way and the lessons learned from this process is described in this paper. It may be useful for mining regions who will face a similar future sooner or later.

By Ebrahim Ghasemi, Mohammad Hossein Kadkhodaei, Mosareza Jalilian

Entry-type mining methods, such as cut and fill method, play a significant role in underground mining, and they are still suitable methods for extracting deposits with irregular shapes and with weak host rocks. In these mining methods, the stability of the open spans is important for improving worker safety and increasing ore recovery. This study focuses on the application of six data mining classification methods, namely multinomial logistic regression (MLR), classification and regression trees (CART), logistic model tree (LMT), decision tree (J48), multivariate adaptive regression spline (MARS), and gene expression programming (GEP), in order to develop predictive models for stability assessment of underground entry-type excavations. For this purpose, a database containing 399 case histories of entry-type excavations from seven Canada underground mines was used. These models predict the stability status of entry-type excavations based on two input parameters, dimensions of the span and rock mass rating (RMR). The performance of developed models was evaluated using six performance metrics namely accuracy (ACC), sensitivity (SE), precision (PR), Matthew’s correlation coefficient (MCC), area under the receiver operating characteristic (ROC) curve (AUC), and performance index (PI). The results showed that all developed models can be used to predict the excavation stability, but the comparison of models indicated that the J48 model provides the highest performance with ACC = 0.900, SE = 0.869, PR = 0.922, MCC = 0.835, AUC = 0.891, and PI = 4.417. Thus, the proposed J48 model can be applied to identify the susceptibility of span instability in the entry-type mining, and if instability has been predicted, the necessary measures, including the use of suitable support systems, can be considered to reduce the casualties resulting from span instability.

Feb 26, 2024

By Jürgen Kretschmann

According to the model of product life cycles, the global coal mining industry is in the stagnation phase. The coal demand of the main consumer, China, has peaked in 2013 and is slowly declining. The Norwegian sovereign wealth fund, the world’s largest, has excluded coal-related companies for ethical reasons. Important players like the UN or the EU have already begun to describe pathways towards decarbonization. Increasing competition between coal mining companies and the mining regions can be expected worldwide if companies want to keep their positions on the global and national coal markets. Companies will focus on the best deposits. European countries like France, Spain, or Germany are only forerunners of this development—their centuries of coal production have been finished. The concept of sustainable development (SD) is fundamentally based on a model of progress where ecological, economic, and social dimensions should be developed equally and positively. But without the idea of competition, the concept of SD is incomplete. Questions arise, such as how can SD be realized on stagnating or declining markets without guarantees for companies “to live forever”? How can SD be a corporate goal in a phase of decline? How can declining mining regions sustainably progress into a better future? The German hard coal mining industry’s lifecycle has ended in 2018 after 60 years of stagnation and decline. As of 2019, all hard coal consumed in Germany will be imported, especially from Colombia, Russia, and South Africa. What has been done in Germany to handle the coal decline in a sustainable way and the lessons learned from this process is described in this paper. It may be useful for mining regions who will face a similar future sooner or later.

By Felicia F. Peng

Two modes of collector addition techniques are applied in the column flotation for cleaning ultra fine coal. The collector can be: 1) added directly into the coal slurry through the feed system; and 2) gasified collector and transported in the gas phase through the bubbles. Operating parameters of the column flotation were investigated through three phases of work plans for Pittsburgh No.8 seam coal. In present study, the column flotation using two modes of collector addition techniques were tested and compared. Ninety percent or higher combustible recovery can be achieved by using both methods. However, utilizing the gasified collector addition technique in column flotation has more potential than direct liquid addition technique to obtain the higher recovery at same collector dosage.

Jan 1, 1993

By F. Calizaya

A booster fan is an underground fan installed in series with a main surface fan and used to boost the air pressure of the ventilation air passing through it. To accomplish this objective, the fan is installed in a permanent stopping and equipped with airlock doors, a monitoring system, and interlocking devices between main and booster fan controls. The stopping and doors are used to prevent flow recirculation, and the monitors to ensure safe operation of the fan. A booster fan, properly sized and sited, can be used to create safe work conditions and allow the extraction of minerals from areas that would otherwise be uneconomic to mine. In deep and large mines with heavy emissions of air contaminants, the required quantities of air can only be supplied by using high pressure fans. These fans will inevitably induce significant losses of fresh airflow through the stoppings and doors. For well defined ventilation circuits, booster fans can be used to decrease the main fan pressures and reduce the leakage flows. However, this will require a good understanding of the correct ventilation practice, from planning to operation and maintenance of booster fans. The objective of this study is to investigate the conditions under which booster fans can be used safely and efficiently in underground coal mines. Specifically, the study is directed at (1) collecting reliable information on airway resistances and flow requirements from two large U.S coal mines, (2) collecting fan performance data from one or more existing coal mine where booster fans are used regularly, (3) monitoring the performance of booster fans in a laboratory model and an experimental mine, (4) developing a booster fan selection method to assist the ventilation engineer at the planning stage, and (5) training six M.S. or Ph.D. graduate students in advanced mine ventilation.

Jan 1, 2010

By W Frint

An area in Southwestern Wyoming is rapidly becoming the soda ash capitol of the world. Starting only 20 years ago from a unique deposit of trona, the out-put has rapidly increased until now about half of the soda ash produced in the United States comes from this area. Chemically, soda ash is sodium carbonate, a large tonnage, widely used alkali. The largest single industrial use is in glass manufacture, where 25 tons of soda ash are used in producing 100 tons of glass. Other big users are the detergent and chemical industries. The trona deposits in the Green River basin of Wyoming, were formed about 75 million years ago as part of a geologic period when an ancient lake alternately went through periods of being a large fresh water or smaller brine lake. Today these deposits lie from 800 to 3000 feet below the surface in a semi-arid, almost desert region just west of the Rocky Mountain Continental Divide at an elevation of 6200 feet. In this area there is a prevailing westerly breeze and almost every afternoon the velocity reaches very windy conditions. Rainfall is minimal, being only 6-8 inches of moisture per year with an evaporation rate exceeding 24-inches. Most of the moisture comes in winter snows or summer thunderstorms. Temperatures are low with below zero weather dur¬ing most of the winter and early morning frost is not uncommon during the summer months. There are many trona beds varying in thickness from a few inches up to 15 feet. The deposits now being mined vary from 8 to 10 feet in thickness. The ore is mined by driving tunnels either via conventional explosives or with continuous boring machines. It is transported to the shafts via conveyor belts

Jan 1, 1972

By L. H. Monaco

"The evolutional process is always about solving existent problems in order to provide further achievements. But the more something evolves, the more challenges it faces towards greater evolution. Industrial automation systems in Mining have also evolved a lot in the past decades, but they now face new challenges about integration: how to integrate different locations and systems, in a way to reduce costs and increase overall mine efficiency and safety for the operation. This paper compares conventional mining process automation architectures vs. a state-of-the-art, completely integrated system using Electrical Integration based on IEC 61850 standard for Substation Automation Systems. Emphasis is placed on the benefits to manage the entire mining plant as a whole, not only looking at the production rates, but also at the energy consumption for each part of process. In addition, it is discussed how an integrated system approach unlocks safety and productivity gains such as overall process optimizations, improved operator effectiveness, increased plant availability, and reduced maintenance costs. INTRODUCTION The world is constantly changing, and evolution is a natural part of mankind history. The role of evolutional process is to solve existent problems, but usually these solutions create new issues that need to be addressed. This scenario is also applicable to the industrial environment, in which the demand for higher profitability and efficiency on their processes requires solutions with more productivity using less resource. This is not different when it comes to energy consumption: how to optimize production rates and reduce energy costs at the same time? Regarding automation systems, the trend for the industries is to focus on four main challenges: how to provide safety for personnel; how to reduce initial investment for new plants; how to connect remote and in harsh locations; and above all how to deal with the lack of integration between several systems."

Jan 1, 2018

By L. M. Yokum

Tremendous strides have been made in front end loaders in the last fifteen years. Fifteen years ago a 2; cubic yard front end loader was the largest standard machine you could purchase. Today there are two commercially available 15 yard front end loaders and many 10 yard front end loaders. The estimated total worldwide market for all front end loaders over one cubic yard has increased to over 30,000 units yearly. The trend for front end loaders, in general, and for the mining market, in particular, is to larger and larger loaders. Today there are 18 cubic yard and a 24 cubic yard front end loader in prototype form. It is not inconceivable that within another fifteen years that there will be front end loaders in the 50 cubic yard class with design features quite different from today's. These larger loaders are being designed at the demand of the mining industry and the design criteria are being directed at this market area. The costs of these larger loaders will be greater per unit of capacity, and it is the intent of the various manufacturers that they will be more reliable, be easier to service, give greater availability, live longer, and cost less to maintain, than previous loaders. It is also the intent of the manufacturers to compete directly with the large mining shovel as the front end loaders become appropriately larger and more reliable. There has been some trend in this direction in the past with smaller shovels and loaders. In Figure No. 1 are data for U.S. production of front end loaders (5-6 cubic yard class and 10 cubic yard class) and U.S. production of cable operation, crawler mounted power shovels, draglines and cranes (1; to 5 cubic yard class) for the years 1965 and 1970. (Source: Bureau of Census, U.S. Department of Commerce.)

Jan 1, 1972

By William C. York-Feirn, Jeffrey H. Kravitz, David Stalfort

"Mining is an inherently risky business. Over the years, major mine disasters have resulted in the deaths and injuries of thousands of miners in the United States. These disasters also resulted in innovations in approaches to mine design, operations and the training of miners and mine rescue teams. The U.S. Congress responded to these disasters with new laws designed to create mandatory safety and health standards as a means to eliminate fatal accidents; to reduce the frequency and severity of nonfatal accidents; to minimize health hazards and to promote improved safety and health conditions in the nation’s mines.Following a mine emergency preparedness and response holistic gap analysis in 2012, the U.S. Mine Safety and Health Administration (MSHA) identified the need for the development of risk and readiness assessment models for MSHA and the mining industry. MSHA’s objective was to evolve existing theoretical concepts for risk and readiness assessment into simplified tools that can be applied by the mining industry for use at operational levels. In 2012, MSHA hired ABS Group, a recognized industry leader in safety risk management and a wholly owned subsidiary of the American Bureau of Shipping, to develop self-assessment models to help meet this objective.In September 2012, MSHA chartered a project to supply the coal mining industry with a pro-active toolset for mine operators to:1. Self-assess the risks associated with underground coal mining operations in order to prevent major mine emergencies.2. Assess the preparedness of mine operators to respond to an emergency.3. Measure the readiness of mine rescue teams and responsible persons to execute emergency plans.MSHA’s objective was to evolve existing theoretical concepts for risk and readiness assessment into simplified tools that can be applied by the coal mining industry for use at operational levels."

Jan 10, 2018

The Global Mining Standards and Guidelines Group (GMSG) is building an international, multi-stakeholder community to advance the availability and use of standards and industry guidelines for the global mining community. Standards and guidelines are key strategic tools for operational excellence, enabling companies to move forward with efficient, innovative operations with reduced risk. Launched in May 2012, the GMSG is the first international center to bring together information, resources and collaborative projects for mining standards and guidelines, in an open, knowledge-sharing forum. The GMSG is supported by five partner organizations providing outreach and helping to guide GMSG activities: the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the Society for Mining, Metallurgy and Exploration (SME), the Australasian Institute of Mining and Metallurgy (AusIMM), the Southern African Institute of Mining and Metallurgy (SAIMM) and the Surface Mining Association for Research and Technology (SMART). GMSG was formed under the CIM Surface Mining Society, though its mandate extends to include underground mining as well. ?SME is supporting the GMSG as a key international activity to advance the implementation of standards and guidelines in our industry, and to provide a forum for our members to access, and contribute to, projects and information to assist their operations,? said SME Executive Director David Kanagy. ?We see the GMSG as a good example of ways the major mining associations can work together for the benefit of all our members.? The GMSG charter encompasses all standards and guidelines that apply to mining; however, a number of subject areas are now being spearheaded by six working groups, namely: ? Access and usage of data from mobile mining equipment onboard systems. ? Operational safety. ? Situational awareness (namely, a unified equipment operator interface). ? Underground operations. ? Asset management and operations data definitions and KPIs. ? Energy in communition.

Oct 1, 2013

By Chee Theng

"Keep calm and carry on mining. That has long been the conventional wisdom in the mining industry, a largely cyclical one that has weathered roller-coaster booms and busts. But in the years from 2002 to 2016, an unprecedented steep rise in commodities prices that lasted a decade and then took a sharp turn downward had made it hard for gold and silver miners to stay the course.“The last 15 years highlighted some of the structural and inherent challenges that our industry has, from product price uncertainty to long lead times to the capital intensity of our business,” said Mitchell Krebs, president and chief executive officer of Coeur Mining, who was the luncheon speaker at the American Exploration & Mining Association’s 122nd Annual Meeting held Dec. 5-9, 2016, in Reno, NV.Looking back, Krebs said, “We were given this enormous gift of a commodities super cycle, and the industry kind of blew the opportunity.” While gold prices rose 319 percent and silver prices rose more than 200 percent over the 2002 to 2016 period, the XAU index of 30 gold and silver mining companies’ stock prices went up by only 20 percent.Entering 2016, precious-metals prices have made a comeback, with gold rallying strongly from a six-year low at the start of the year. This time, the industry is ready. Companies are leaner and meaner, with lower costs, reduced debt and an increased focus on higher grades and quality ounces. Although opportunities were missed in the past, the industry has got its act together and is now well positioned to take advantage of a price upswing and even to show profits when prices fall, as they did in August 2016, pushed down by a strong dollar."

Feb 1, 2017

By Frank Kitzinger, Jacques Nantel

Under special circumstances, electrical energy can successfully replace chemical ex­plosives for blasting rock. High pressure plasma can be generated in the confines of a drillhole, by a powerful electrical dis­charge. The energy level can be adjusted to replicate the effect of a high explosive. The main difference is the almost total ab­sence of gas generation with electric blast­ing. Once the rock fractures, the small amount of matter used for generating the plasma rapidly cools off and regains its former volume. High speed film studies clearly show, that the initial speed of blasted rock fragments is the greatest, no further gas propelled acceleration takes place .. Figure 1, shows a typical electric blast of an oversize boulder of quarzite in an open pit mine.

Jan 1, 1992

By Ron VanRiper, Ben W. Burdett, Randy A. Ynchausti, Jeff D. McKay, Dan Lampshire, Thomas W. Toronto

An adaptive process control system was installed in Cortez Gold Mines Mill #2 Grinding Plant in Nevada. The installation, commissioning, and testing of the system took approximately 80 manweeks, but final test results show that the system paid for itself through increased throughput within two weeks of commissioning. Both crisp and fuzzy rules are used in the expert rule base which is also integrated with continually adapting neural network models. The expert rules and models are used by predictors, and optimizers to allow the control system to provide optimum process performance under continually varying feed conditions. The selection, installation, rule and predictor configuration, and statistically verifiable testing of the control system in the Cortez Gold Mines Mill #2 Grinding Plant is described in the paper.

Jan 1, 1999

By R. J. Essex

In support of the Conceptual Design of a Nuclear Waste Repository in Salt, a confined core pillar design method developed by others was reviewed. The method, which was developed for applications in coal, represents the confined strength of the pillar material in terms of a linear failure criterion. However, triaxial compression strength tests conducted on salt samples indicate that a non-linear strength criterion is more appropriate for salt. The rationale behind the confined core method is reviewed. A rederivation of the confined core method is then presented that incorporates a non-linear strength criterion. Benefits of the modified method are that the strength of the confined pillar core can be more accurately represented, and that two contributors of pillar strength, rather than one, can be addressed.

Jan 1, 1988

By David R. Crouthamel, Francis L. Fong, Troy L. Page

This paper focuses on the results and the performance of the grouting program as a means to control groundwater infiltration during the excavation of the 7.7 km (25,160 lf.), 3.5m (11 ft. - 7 in.) diameter Inter-Island Tunnel beneath Boston Harbor in Massachusetts. Two major operations of grouting were performed - water cutoff grouting behind the tunnel heading after excavation and face grouting ahead of the Tunnel Boring Machine (TBM) operation. An array of products from cementitious to chemical grouts and various grouting procedures and equipment were employed to evaluate their effectiveness in controlling the water in-flows. Evaluation of the overall performance of each of the grouting rations, overall costs and comparison of face grouting versus post excavation grouting is made.

Jan 1, 1997

By P. Coleman, J. C. Kerkering, S. Iverson

Fault tree analysis is a systematic safety analysis tool that proceeds deductively from the occurrence of an undesired event (accident) to the identification of the root causes of that event. One recurring mine safety problem-a dozer falling into a void over a drawpoint on a coal surge pile-was analyzed using available, inexpensive fault tree programs on a personal computer. The analysis identified basic and intermediate events that led to the burial of the dozer and graphically depicted the interrelationship between these various subordinate events as well as the various chain of events leading up to the primary event. A sensitivity analysis on these probabilities showed which events had the greatest influence on dozer burial in a coal surge pile.

Jan 1, 2001

By K. Nielsen, V. Bauer

"The paper presents a brief overview of the long mining history and the more recent political development in the Slovak and Czech Republics as well as in Norway and Sweden. Mining used to be very important sources of economic wealth in the four countries, but in today’s economy does exploitation of non-energy minerals usually account for less than one per cent of the GNP. The paper will discuss and compare the mining legislation, land use planning and mineral policies framework in the four countries and how this may influence sustainable management of mineral resources including planning for mineral supply, landbanks and sterilisation of resources. The paper will then identify some positive and negative elements in each country’s political and administrative framework."

Jan 1, 2005

By P. E. Sarquis, R. Lenzo

The concentration of barite by gravity separation generates substantial quantities of fine particle wastes, and it is estimated that =40% of the contained barite is lost to these waste streams. In this study, froth flotation was examined as a potential method for the recovery of fine-barite particles. The study included the use of kinetic equations to estimate the variables affecting flotation, batch-scale rougher flotation tests to study the flotation variables and an examination of alternatives for the cleaning of the rougher concentrate. Results indicated that a concentrate grade of 96.5% could be achieved with a recovery of 77.5%. Although barite flotation from industrial wastes is more difficult than direct barite flotation, the process has considerable economic potential.

Jan 1, 1996