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By Mogens Henriksen

In the past decade, numerous urge scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid ratio. A typical reverse circulation air lift system is depicted in Figure 1. Allen1 has described a number of reverse air lift drilling projects. Although cited examples are generally related to large diameter holes, the method has seen use in other applications such as sand dredging, chemical pumping, water well pumping and continuous coring. One particular benefit obtained with enclosed reverse circulation drilling is elimination of lost circulation. The required air/water ratio for pumping at a given submergence and lift has been established experimentally by Gibbs2. His data, however, do not reflect sensitivity of flowrate to air/water ratio. Further, in Gibbs' work, air apparently is injected continuously along the column of water. This configuration differs from that used in reverse air lift drilling where air is injected at discrete points only. Gas lift theory has received considerable attention over the past decades. Orldszewski3 defined flow regimes in two phase flow. Griffith and Wallis4 determined relative velocities of gas to liquid. Two-phase flow has been studied extensively for oil transport in inclined and vertical pipes by Chierici et a15, Beggs and Brill6, and Gould, Tek and Katz.7

Jan 1, 1977

By John Jonkman

Two major changes occured during the last 5 years in the applications of computers. First, the cost of computer equipment decreased drastically in an era of high inflation. Second, technological breakthroughs in hardware and software have been applied successfully so that the average person can successfully utilize the computer without having to be a computer expert himself. The mining industry has recognized that computing technology has evolved to a point where it can be applied successfully to assist in improving productivity. Since equipment downtime is one of the major reasons for lost production, the Kennecott Minerals Company has developed a comprehensive maintenance information system which now assists the maintenance department in minimizing equipment downtimes. This paper discusses the primary features and functions of this system, the state-of-the-art technology that has been applied, and the benefits that resulted from using this system. Programs to support mobile equipment maintenance scheduling, which currently are under development, are reviewed and a summary of future applications is given.

Jan 1, 1982

By Steve L. Bessinger, Luis B. Giraldo, Joram Shenhar, James D. Pile

This paper discusses the Helical Drag Bit (HDB) and its rock drilling applications with an emphasis on use in mining operations. The HDB is a drilling tool that employs cutting members arranged in a pattern to form a helical groove or thread within a borehole. This pattern of cutters can be used for several purposes including roof bolting in mining, interpretation of the lithology of the strata being drilled and low energy consumption drilling. Laboratory and field experiments have consistently shown increase of roof bolt-anchoring capacities in weak rock of more than 100% using the short encapsulation pull test method when boreholes are conditioned using the HDB. In 2004 a series of tests conducted in mines with weak roofs demonstrated the benefits of HDB technology for roof bolting applications in mining. HDB technology offers opportunities for new and beneficial approaches to interpret the geology of roof strata. During conventional drilling, traditional approaches to determine rock properties require simultaneous measurement of several parameters such as thrust, rotational velocity, torque and penetration rate. The unique geometry of the HDB possesses a characteristic that allows determination of the mechanical properties of the rock being drilled by measuring torque as a single drilling parameter. This capability greatly simplifies the process of determining rock properties and provides reliable results. Additionally, HDB technology has been demonstrated to offer significant advantages for rock drilling. A substantial portion of the rock is removed by the fracturing of the internal thread created in the rock bore by the tool taking advantage of the weakness of the rock in tension. Because the rock chips obtained in this process are relatively large, savings in energy are realized when compared to traditional drilling technologies.

Jan 1, 2005

By Wei Bin, Liu Zhe, Liping Xiao, Jichi Bai

The Acid Mine Drainage has characteristics of low pH, high concentrations of heavy metal ions, such as Fe2+, Mn2+, Cu2+ and Zn2+. In this paper, the composite particles that consisted of bentonite and steel slags were used to dispose the Acid Mine Drainage. Bentonite is the mineral materials and can adsorb heavy metal ions excellently. The steel slags are alkaline and industrial solid waste for the treatment of the Acid Mine Drainage. The main influencing factors, such as adsorbent dosages, shaking rates, concentrations of heavy metal ions, temperatures, adsorption time and pH value were studied by the static experiment. Increasing the adsorbent dosages and the concentrations of the heavy metal ions, speeding up the shaking rates, raising the temperatures, extending the adsorption time and improving pH would improve the removal efficiencies of heavy metal ions. Through considering the removal efficiencies and the treatment costs, the optimum reaction conditions for the four kinds of heavy metal ions were obtained. The adsorbent dosage 21 mg/L, the rotational speed 120 r / min, the temperature 25?, adsorption time 100 min and the initial wastewater pH 7. The four kinds of heavy metal ions existed independently in the simulated mine wastewater. The highest initial concentrations of Fe2+, Mn2+, Cu2+ and Zn2+ were 150 mg/L, 100 mg/L, 170 mg/L and 140 mg/L respectively. The removal rates were 93.42%, 92.64%, 93.86% and 95.17% respectively. The determination of the particles’ SEM-EDS Microscopic characterization showed the composite particles could play a part in neutralizing, absorbing and the chemical precipitation. The acidity decreased notably and the heavy metal ions of Fe2+, Mn2+, Cu2+ and Zn2+were adsorbed and precipitated effectively. The research results can extend the practical engineering application of the composite particles.

Jan 1, 2017

By W. R. Penney, J. M. Richardson, J. Y. Oldshue

Introduction The mining industry has for years underrated the value of mixing in mineral processing unit operations. In present-day operations where leaching is playing an ever increasing role in the total profit picture, the need for good mixing is becoming more obvious. The engineer in the research laboratory and in the operations is by necessity becoming more familiar with the concepts of mixing. This section is designed to provide the engineer with mixing data and correlations sufficient to assist in the general planning of simple mixing systems.

Jan 1, 1985

By James A. Pendleton

The Legislature of the State of Colorado adopted House Bill 1223, "The Colorado Surface Coal Mining Reclamation Act" (The State Act), in 1979. This Act provided for the creation of a state regulatory program as accommodated within Public Law 95-87, "The Surface Mining Control and Reclamation Act of 1977" (SMCRA). Section 34-33-121(2)(a) of the Colorado Revised Statutes (CRS) and Section 516(b) of Public Law 95-87, identically require the underground coal mine operator to "Adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mined stability, and maintain the value and reasonably foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." On July 23, 1980, the Colorado Mined Land Reclamation Board adopted regulations to administer and enforce the State Act. Amendments to the Rules, including the subsidence regulations were adopted by the Board in August of 1981. These regulations require the prediction, monitoring and mitigation of "material damage" caused by subsidence.

Jan 1, 1985

By S. B. Bealko

Mining haul trucks comprise the majority of the equipment used in underground limestone mining operations and are known to emit high levels of noise. A previous study conducted by the National Institute for Occupational Safety and Health (NIOSH) indicates that 70-90 percent of all miners have a noise-induced hearing loss (NIHL) great enough to be classified as a hearing disability by retirement age. These results demonstrate the public health need to protect the hearing of workers in the mining industry, including haul truck drivers. ng of workers in the mining industry, including haul truck drivers. Cab enclosures present an opportunity to isolate the haul truck operator from both truck and other noise in the mining environment. A total of twenty-five haul truck cabs were studied which were divided into three style (treatment) categories determined by soundproofing features and technology for noise reduction: old-, new-, and retrofitted-style. This study examines the contribution of cab acoustics, operator performance, and maintenance to noise reduction for each cab style. Dosimeters were used to measure 8-hr time weighted average sound pressure levels (TWA8 SPLs) inside and outside the cabs to determine if different acoustical treatments affect cab attenuation. Adherence to the Mine Safety and Health Administration (MSHA) Permissible Exposure Limit (PEL) of 90 dB TWA8 (with a 90 dB threshold) was used as the main indicator of overall noise reduction achieved. Dosimetery results indicate only 2% of the samples exceeded the PEL, but samples could still be reduced much further. Descriptive and comparative statistics indicate that noise levels inside the new-style cabs are significantly lower than the other two cab styles. Also, data suggest that there is no difference in noise exposures when comparing the old-style to retrofitted cab styles. Operator influence (opening doors and windows) was a significant factor for increasing noise exposure. This paper demonstrates that properly designed cabs can achieve major noise reductions, but noise levels could still be reduced much further below the MSHA PEL. New-style cabs, equipped with modern noise-reduction treatments, exhibit much lower noise exposures than the other two cabs styles, and the effectiveness of the current noise-reduction treatments for retrofitted cabs is questionable. Haul truck driver observations indicate that improved noise exposure reduction training is needed. Finally, specific targets for future noise reduction research are suggested that will further contribute to the prevention of hearing loss for haul truck operators.

Jan 1, 2008

By Daniel H. Stevenson

Safety and health are fundamental values at Barrick Goldstrike. An effective safety and health program protects employees, controls costs and increases productivity. Barrick Goldstrike believes that all occupational injuries and illnesses can be prevented and that safety must be the responsibility of every employee on the property. Safety and health must be thoroughly integrated with the company's efforts to maximize production at the lowest reasonable cost. The goals of safety and production are not mutually exclusive. They must work together to achieve safe production. Barrick Goldstrike began to mine the Betze deposit in 1987. From 1987 to 1992, Barrick employed a traditional safety system using safety specialists on each crew. These specialists were responsible for ensuring that the work areas were safe and that employees were properly protected and trained in safe work procedures. As the work force increased, it became apparent that this system was not the most effective method of ensuring safe production. In 1992, Barrick Goldstrike implemented a loss control program. It was modeled after the International Loss Control Institutes's (ILCI) International Mine Safety Rating System. This program was based on the philosophy that safety is a management responsibility. It can be managed in the same manner that production and cost issues are managed. Under the loss control system, safety needs are identified and evaluated. Programs with performance standards are developed and implemented and the activities and results are regularly monitored. Between 1992 and 1996, Barrick Goldstrike worked at developing and improving its safety management systems. These efforts had a positive return. The incident rates began to decline as these improved systems were implemented. Studies were undertaken in early 1996 to evaluate the effectiveness of the safety and loss control programs in reducing accidents. The studies showed a strong correlation between the implementation of the loss control programs and the resulting reduction in all accidents. Studies in the process division revealed that Barrick had experienced reductions in personal injury accidents from the projected number that could have been expected had no changes been instituted. These reductions ranged from 39% in 1993 to 59% in 1995. These reductions from the projected rates held true for all types of accidents; personal injury, property damage and Mine Safety and Health Administration (MSHA) reportable.

Jan 1, 1997

By Emily Wortman-Wunder

As the 2012 president of the Society for Mining, Metallurgy, and Exploration, Inc., I am pleased to present the 2012 issue of the Transactions of the Society for Mining, Metallurgy, and Exploration, Vol. 332. A significant portion of the contribution that we make as a professional society is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of AIME; those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2012 Transactions is the third Transactions to take advantage of new publication technologies. It is available solely as an online subscription. The new format better suits the way this material is used and, ultimately, better enables the transfer and dissemination of knowledge. The 2012 Transactions contains some of the most interesting research from the past year, including a paper on the uranium boom in Namibia, work on improving the safety of coal pillar extraction, ways to improve the optimization and efficiency of various mine activities and the newest research from the U.S. National Institute for Occupational Safety and Health (NIOSH). The 2012 Transactions consists of a total of 67 technical papers (550 pages, including index), including all 18 papers published in 2012 in the Technical Papers Section of Mining Engineering magazine (Vol. 64) and all 31 papers published in 2012 in Minerals & Metallurgical Processing (Vol. 29). Additionally, this volume contains 18 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All 67 technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our publications staff. As the 2012 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume.

Jan 1, 2012

By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996

By S. K. Mukherjee, M. M. Singh, N. I. Jayaramn

In underground mining operations, ventilation and water sprays are the common methods of controlling dust. In recent years, there has been a proliferation of technical literature dealing with water sprays for dust control. However, guidelines for the design of an effective water spray system have not been presented to the mining industry. This paper recommends guidelines for water spray systems to control dust in underground mining operations. These guidelines suggest type, number, location, and orientation of nozzles; desirable operating water pressure; and associated filtration system.

Jan 1, 1987

By A. W. Deurbrouck, W. W. Agey

Introduction The modern wet concentrating table is a rectangular or rhomboid shaped normally rimed-deck operated in essentially a horizontal plane (Fig. 23). A drive mechanism imparts a differential motion to the deck along its long axis while water flows by gravity along the short axis. Tables are currently employed for processing large tonnages of coal and lesser tonnages of barite, beach sands, chrome, glass sand, garnet, iron, manganese, mica, phosphate, potash, tantalum, tin, tita-

Jan 1, 1985

By A. M. Tunstall

Blasting is commonly viewed separately from mechanical handling and crushing. This view is misleading because the degree of fragmentation achieved by blasting can have a significant effect on the efficiency of these processes and, hence, on the overall cost of the mining operation. In this paper, aspects of blasting and crushing and their interaction are examined. A case study is also presented that dramatically illustrates the influence of blast fragmentation on subsequent processing and on the financial implications involved.

Jan 1, 1998

By Giuseppe Bonifazi

This study examines the problems involved with the control of characteristics of the products resulting from comminution operations. A methodology of investigation based on texture analysis procedures by image processing techniques of the comminution product is proposed. Some examples of applications are considered with particular reference to comminution products of different textural, structural and mechanical characteristics. The advantages and the limites of this method of approach are, indicated, both as regards performance of the investigations and subsequent processing of results.

Jan 1, 1989

By G. Knight

It is shown that the dust exposure of all underground workers varies greatly from day to day even though each man did the same job in the same working place each day. The variability follows a logarithmic normal distribution with a geometric standard deviation of about 1.6 for the three dust assessments; total respirable dust, respirable combustible dust and respirable quartz dust in both mines studied. The variability was homogeneous for all men and most jobs. The differences between men doing the same job was found not to be significant and it is suggested that the dust sampling program should determine the average for each job and use this as the best estimate of the exposure for each man.

Jan 1, 1980

By Sukumar Bandopadhyay

A present dominant problem is that of high downtime of the longwall shearer used in the coal production process. The means by which this problem can be overcome are many, but one of, the most important ones is that the-use of an expert system can reduce diagnostic and repair time. In this paper, a fault-diagnostic expert system model is presented. Specifically, the diagnostic architecture of the longwall shearer expert system and its use for diagnostic reasoning are discussed.

Jan 1, 1989

By Matthew J. Hrebar

Dragline stripping operations account for over one-half of the U.S. bituminous coal production mined by surface coal mining methods. The dragline is a popular stripping tool because of its flexibility in varying overburden depths and relatively low operating costs per cubic yard of overburden. Because of the relatively high capital costs of the machines and their use as a primary stripping tool, the selection process is an important step in the mine planning procedure.

Jan 1, 1979

By A. Bumanis, K. S. Bawa

INTRODUCTION A rail rapid transit system called the "Metro" system is presently under construction in the Nation's Capital area. The agency responsible for the design and construction of the Metro system is the Washington Metropolitan Area Transit Authority, an independent tristate organization set up under an Act of Congress and financed by federal, state, and local public funds supplemented by revenue bonds. When completed, the Metro system will comprise nearly 100 route miles. About fifteen percent of this mileage is now under construction, while designs for the-remainder are in progress. The system is scheduled for completion in about eight years at a cost of approximately 3 billion dollars. The Metro system will involve nearly all types of construction generally used for rapid rail transit projects. About half of the mileage will be underground, comprising approximately 16 miles of rock tunnels, 10 miles of earth tunnels, and nearly 21 miles of cut-and-cover construction in earth (see Figure 1.). The remaining 51 miles of the system is planned to be constructed on the surface as at-grade or elevated structures. The system includes 86 passenger stations, 53 of which will be underground structures. Twelve of the underground stations will be large size chambers in rock while other underground stations will be constructed in earth as cut-and-cover structures. Thus, about one-fifth of the system will be designed as underground structures, namely tunnels and stations, in rock. Such designs in rock resulted from the existence of bedrock (schistose gneiss) at reasonable depths generally in the north and northwest

Jan 1, 1997

By M. J. Garcia, Howard Hallman, G. M. T. Marshall, Ken Higby, Louis Cope, Robert S. Hess, John Peters, A. G. Law, William C. Larson

After a good year in 1979-strong mineral demand, adequate prices for most metals, minimal labor problems-1980 was not so good. The US produced $24.8 billion worth of nonfuel minerals last year, up 3.5% from 1979, according to preliminary US Bureau of Mines figures. But the $800 million increase was the smallest annual gain since 1977 and reflected reduced auto and construction industry demand, strikes, and energy shortages. Preliminary figures for 68 minerals show that production of 42 decreased, 25 increased, and one was unchanged. Production of 11 of 21 US-produced minerals was up. Noteworthy mineral events in 1980 included a copper industry strike, increased gold and silver prices, troubles in the iron ore and uranium industries, discussion about a US nonfuels mineral policy, and corporate interest in mining companies as merger targets. Recessionary conditions experienced by the Western world in 1980 resulted in a slowdown in new mine development, evident in the relative scarcity of major new base metal projects. This could lead to short term supply/demand anomalies within the next few years which, in turn, could have a significant effect on metal prices, according to Mining Magazine (Jan. 1981). World Mining (Sept. 1980) noted that US mining strength is in open pit operations. A much lower tonnage is mined underground and is centralized in trona, uranium, lead, zinc, molybdenum, potash and, to a lesser extent, copper. The most notable increase in new underground mines has been in Wyoming's trona district where new mines are being developed and production will increase, the magazine said.

Jan 5, 1981

By Raymond F. Mikesell

This paper evaluates the contributions of "third parties" to surplus capacity in the world metals industries in the 1980s. Special attention is given to the role of international development agencies, such as the World Bank, that have made project loans to state mining enterprises. The paper also reviews the contributions to surplus capacity of the International Monetary Fund and evaluates the large volume of credits from commercial banks to developing countries. Although the credits to Third World countries during the 1970s facilitated the expansion of mining capacity in those countries, no one source of financing can be held responsible for a significant portion of the expansion.

Jan 1, 1989