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By N. R. Allen, J. D. Steenkamp

Oxidative roasting is applied on an industrial scale to beneficiate ilmenite concentrates from South African East Coast heavy minerals deposits - the aim is to increase the magnetic susceptibility of ilmenite to allow magnetic separation from chromite. The intention of this paper is to give researchers new to the field an overview of the beneficiation of ilmenite through roasting and magnetic separation, touching on the relevant fundamental aspects of magnetism.

Jan 1, 2005

By Russel Delmar

Construction of Ontario Power Generation?s 12.8-m diameter, 10.4-km long water diversion tunnel in Niagara Falls, Ontario, is underway. The tunnel is being excavated by means of a 14.44-m diameter open gripper Tunnel Boring Machine. The tunnel lining is constructed as a two-pass system with the initial lining consisting of rock bolts, mesh, steel channels or ribs, and shotcrete, and the final lining consisting of pre-stressed cast-in-place concrete with a waterproof membrane. This paper describes salient design and construction aspects as follows: ? Regional and Site Geology ? Tunnel Layout and Design ? TBM Tunnelling and Cast-in-place Concrete Lining Construction

Jan 1, 2008

By R. J. Baumgartner

Sustainability issues are from rising interest and importance for the mineral industry worldwide. In order to bring them into management processes and to improve decision processes, economic, ecological and social aspects of products, services or technologies have to be assessed. In this paper, the concept of integrated sustainability assessment is presented. Each aspect is assessed with quantitative or qualitative methods. The results of these ecological, social and economic sub-assessments are integrated by the means of Fuzzy Logic in order to regard preferences of decision maker and circumstances of decision situation. An example demonstrates the application of this new instrument.

Jan 1, 2005

By D. X. Tang, G. Wilson, S. S. Peng

Design and implementation of a roof bolting plan requires reliable geotechnical information of strata, such as rock strength, and locations of interfaces and voids/fractures. The drilling parameters obtained during normal roof bolt installation cycle provide a fast and economic way to gather information on the geological structure within the bolted horizon. The purpose of this research project is to develop a method for identifying the geological features in the mine roof strata based on drilling parameters of roof bolter. The criterion for void/fracture prediction has been developed and proven valid. This paper focuses on the estimation of the strength of roof strata by using drilling parameters. Based on the results of a series of underground and laboratory tests, feed pressure is found to be the most sensitive parameter when the strength of roof strata changes. Moreover, it was also found that both penetration rate and rotation rate have obvious impact on the magnitude of feed pressure. Based on these findings, the criterion for the estimation of roof strata strength has been developed using the relationship among feed pressure, penetration rate and rotation rate and implemented in MRGIS.

Jan 1, 2006

By M. Maier

Geographic Information Systems (GIS) has evolved into a powerful tool for analyzing spatial and attribute data in many industries including mining. Modern field data collection techniques add another dimension to the use of data in the field and enhance the utilization of GIS for mining applications. This discussion will review how field data is collected and how office data and maps can be taken into the field to be analyzed and verified using pen-based computers and differentially corrected GPS.

Jan 1, 2001

By Paul R. Smith

The Colorado School of Mines Research Institute (CSMRI) was founded in 1949 to fill mining industry and government needs for minerals research and development. The operations of scores of mines, mills, and plants around the world are based on the results of work done by the Research Institute. Among other things, the Research Institute conducts studies in geology, mine planning, mineralogy, size reduction, minerals processing, and hydrometallurgical techniques in extractive metallurgy. Many CSMRI projects also involve energy and environmental considerations. What follows is a summary of some of the studies in which the Research Institute has been and is currently involved, as well as some comments on trends and developments in the industry.

Jan 2, 1982

By J. D. Morgan

Introduction In 1986, the US economy passed the $4 trillion mark. However, the value of domestically processed materials of mineral origin fell slightly to $240 billion. The value of metals produced from US ores was unchanged at $5.6 billion, as was recycled scrap at $4 billion, while the value of industrial minerals rose slightly to $17.9 billion. Consumer demand strongly affects mining and the US economy is relatively saturated with longlived products. Moreover, in recent years there has been a steady increase in consumer, mortgage, and federal debt, inhibiting new purchases of goods. Motor vehicles and housing are major traditional markets for mineral materials. However, the 242 million US citizens already possess 170 million licensed motor vehicles and 92 million dwelling units. In 1986, domestic motor vehicle production fell 3%, to 11.3 million units, while new housing starts rose slightly to 1.8 million units. Nearly all mineral commodities move relatively freely in world trade. As detailed in Figs. 1 and 2, in the last three decades world production of major mineral materials has greatly increased. At present, substantial excess productive capacity exists not only in the US but also in many other countries. Consequently, the US mineral industry is encountering increasing competition from other sources, along with increasing competition from newer, engineered materials. For example, US production of plas¬tics has risen from 900 kt (1 million st) in 1950 to 22.7 Mt (25 million st) in 1986 - on a volume basis significantly greater than steel. Plastics, too, are mineral-based materials, some 7% of petrochemicals going to their manufacture. 1986 saw increased calls for protection. But President Reagan, in his 1987 State of the Union Message and Economic Report to the Congress, reaffirmed adherence to a policy of free and fair trade. However, he stressed the need for increased efforts to open foreign markets to US exports and to increase competitiveness of US industry US imports of mineral-based minerals in 1986 were valued at $40 billion and exports at $24 billion. Strategic minerals As detailed in Fig. 3, imports supplied a significant proportion of total US consumption of several important materials, including many classified as "strategic and critical." There were no changes in stockpile policy during the year. Congress debated the President's 1985 proposals to reduce stocks of World War II-type materials and to focus more on high technology materials needed for the cutting edge of future military material. But no final action resulted. However, Congressional concern about apartheid in South Africa did result in increasing pressure to limit imports of South African minerals. Meanwhile, the National Critical Materials Council in the Executive Office of the President intensified its efforts to be better able to advise the President. The Defense Production Act provides authority for priorities and allocations, supply expansions, voluntary agreements, and

Jan 5, 1987

By W. Rogers

Blast-induced rock mass displacement can have a significant impact on ore loss & dilution. The mischaracterisation of the grade boundaries both prior to, as well as a result of blasting can lead to significant financial losses on account of ore loss and dilution. Ore dilution occurs when waste material is miscategorised as ore and sent for processing or stockpiling, diluting the run of mine head grade and recovery. Ore loss takes place when valuable mineral is miscategorised as waste and sent to the waste dumps, thus never being processed and recovered. Extensive research has been conducted at the University of Queensland over the last fifteen years to understand the impact of blast movement on ore loss and dilution. Recent outcomes of this research have developed innovative tools and techniques to measure and model blast movement. These techniques have been implemented at Ahafo gold mine in Ghana to understand blast movement dynamics and to implement solutions to reduce blast-induced ore loss and dilution. These solutions are validated through controlled trials and have been incorporated into site standard operating procedures to sustain the benefits.

Jan 1, 2012

By İbrahim Çınar, Hakan Özşen

Mine workers in heavy and dangerous work are under several physical risk factors, for example temperature, humidity, noise, vibration, lighting and air velocity. Thermal comfort includes parameters such as air temperature, air humidity, air flow rate, radiant heat, metabolic rate and garment insulation. In this study, thermal comfort conditions were evaluated using thermal comfort indices defined as predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) which were determined by measurements taken from an underground coal mine for approximately 100 days. Although the metabolic rate (light work) was kept at 2 met, it was found that predicted mean vote ranged between − 2.58 and 1.68. The predicted percentage dissatisfied index was found to reach 95%. According to the results, it can be seen that thermal comfort may have negative effects on occupational health and safety. The change in thermal comfort index values in the Soma Underground Coal Mine was investigated in detail and the reasons for the changes were determined. Furthermore, determining the optimal working environment for the mine workers was also an aim of this study.

In spite of a global economy that continues to seesaw and a U.S. Congress that is at odds with the president and themselves, cities around the world are still spending billions on their infrastructure. And that bodes well for the underground construction and tunneling industry and the professionals who work in it. In June, 1,405 of those professionals gathered in San Francisco, CA for the Rapid Excavation and Tunneling Conference (RETC). In addition to the first rate technical programming, attendees were able to see first-hand the latest in tunneling technology from 127 exhibitors who occupied 152 booths. Two short courses preceded the conference and two field trips were offered following the conference.

Jan 1, 2011

While SME is hosting its Annual Meeting at the Phoenix Convention Center, Feb. 28 to March 3, one of the finest collections of mining history will be on display just 15 blocks away at the Arizona Mining and Mineral Museum. Inside the museum, visitors will be treated to a treasure trove of minerals, gems, me¬teorites, rocks, fossils, mining artifacts, historical exhibits and interactive displays on modern mining. The museum is located at 1502 West Washington. For SME Annual Meeting attendees, this is a free, eight-minute Dash bus ride 15 blocks west of the Phoenix Convention Center.

Jan 1, 2010

Remote methane detection State and federal regulations require frequent measurements to verify that safe methane levels are maintained in underground coal mines. Ventilation control is the primary means of maintaining safe methane levels. In the immediate face area, where the highest methane levels occur, methane measurements are required every 20 minutes during active mining. To perform these measurements, temporary roof supports must be erected. This allows a miner to reach the face. There a hand-held methanometer is used to make the measurements. This procedure is time consuming and potentially hazardous. To facilitate the measuring process and reduce the miner's exposure to roof falls, the US Bureau of Mines has developed a prototype optical device. It can measure methane remotely from distances up to 12 m (40 ft). The device uses two infrared signals, reflected from the coal face, rib, or roof. One signal is absorbed by the methane, the other is not. The ratio of the two signals determines the average methane concentration in the face area. The prototype detector has also been successfully tested at the Lake Lynn, PA Laboratory. Instantaneous responses were obtained for methane in the ventilation airflow and for methane layered near the roof. Conventional methanometers required from five to 25 seconds to respond to the methane in the ventilation airflow. They did not respond to methane in the roof layer. For more information about the Bureau of Mines' remote detection research, contact Richard W. Watson, US Bureau of Mines, Pittsburgh Research Center, Box 18070, Cochrans Mill Road, Pittsburgh, PA 15236 or call (412) 892-6630. Ignition suppression system The incidence has increased of fractional spark ignition at the mine face. One reason is the advent of mechanical mining. Another is the more difficult ventilation conditions associated with deeper and more extensive underground workings. To cope with the problem of frictional ignition, the Bureau of Mines initiated research to develop a system that would provide rapid detection of incipient methane-air ignition. Then, rapid dispersion of a quenching agent would ensure that the methane flame was extinguished while it was still relatively small. This concept was successfully demonstrated by suppressing explosions in the Bureau's Bruceton, PA experimental mine. But the bulkiness of the early storage-dispersal system proved impractical to retrofit onto face equipment. In a cooperative effort by the Bureau and the Mine Safety and Health Administration, a more compact system has been developed and is being tested. A continuous mining machine has been equipped with four 1.8-m-long (6-ft-long) and two

Jan 9, 1987

By B. Burke, R. Colquhoun, K. Thomas, R. Walton, D. Fentie

The new Roasting Facility at Barrick’s Goldstrike Mine in Nevada, U.S.A. was developed to process 12,000 tons per day of refractory gold ore. The process consists of crushing, dry grinding, roasting, extensive gas purification, calcine quenching and leaching in the presence of activated carbon. The new plant is integrated into the existing Goldstrike facility, treating ore from both open pit and underground sources. The process design, procurement, construction and commissioning of the Roaster facility was performed successfully over a 3½ year period with peaks of 400 engineering personnel and 950 construction personnel supporting the project. The US$330,000,000 project was completed ahead of schedule and under budget. The commissioning was well planned and proceeded smoothly through a rapid start-up to achieve all primary goals within three months of the start of processing of ore.

Jan 1, 2001

By John Dasher

In 1980, some US cars were designed and built to metric dimensions; wine and gas were sold by the liter; and the March of Dimes Walkathon was measured in kilometers. Although the US Congress has taken a ''soft" approach to metrication, and public resistance to the idea remains strong, the use of metric units is becoming more and more widespread. As the minerals industry becomes more international in scope, US mining companies are converting to the metric system-particularly those companies with business interests overseas.

Jan 2, 1981

By Marianne Snedeker

In January we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. At the same time we hired an outside firm, READEX Inc., of St. Paul, MN, to send the same questionnaire to a sampling of about 1000 US members, selected on an nth name basis, so that we could have some preliminary numbers for the Annual Meeting in February. READEX sent us the final results of its survey in March. At that time, 525 responses of the 992 surveys sent out had been returned, for a 52.9% response, an extraordinarily high return for a low-key (no incentive for return) random sampling. On May 7, we cut off on tabulating returns from the magazine so that we could report the results to you in this issue. At that time, we had 594 questionnaires returned. Our 594 and READEX's 525 (we have assumed that relatively few people returned both), represent a 1119 return, about 3.5% of the approximately 32,000 who received the January issue of ME. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded, told us something positive-you look at or read the magazine. Of the 1119 respondents, 1068 or 95.4% indicated that they had read or looked through the November and/or December issues. Those of you who refer to the magazine once are 466 or 42.6%. Those of you who refer to the magazine two or three times are 559 or 51.1%. Those of you who refer to the magazine four or more times are 68 or 6.2%. How much time do you spend reading the magazine? Of those responding to this question: 186 spent up to 1/2 hr 16.6% 590 spent up to 1 hr 52.7% 292 spent 1-2 hr 26.1% 51 spent more than 2 hr 4.6% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 764 or 69.4%, clip your magazine for further reference. Also, many of you, 513 or 64.2%, do not pass your copy on to another reader, indicating perhaps that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 2 people - 159 - 20.0% 3-5 people - 95 - 11.9% 5 or more - 31 - 3.9% Answers to what portions of the magazine you find useful indicated that the top three were Industry News, feature articles, and Technical Papers; see Table 1. The "other" category included advertising-display, classified, and employment-Coming Events, product information, Washington Survey, new books, the reader service card, and Engineering Fundamentals. Of those responding, 797 or 75.3% indicated a preference for dual notation of SI (metric) with English units; 228 or 21.5% preferred all SI units; while 34 or 3.2% preferred SI with dual notation of other metric units. Based on the preliminary numbers reported by READEX for this question, the MINING ENGINEERING Committee in February voted to return to a policy of dual notation. This decision has been implemented. We asked for your appraisal of the technical level of the magazine. Of those responding, 78 or 7.4% indicated it is too technical, 147 or 13.8% indicated it is not technical enough, and 836 or 78.8% judged it to have the correct tech¬nical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 32 said no, but an overwhelming 97% (1024) said yes. Of the specific topics, 785 like history, 558 political or socioeconomic articles, 440 career development, and 373 human interest. Other topics suggested included new disciplines, mineral resources of the world by

Jan 6, 1982

By L. J. Prosser, A. T. Iannacchione

Unfortunately from 1991 through 1995, 44 miners were fatally injured in the stone industry. Of these 12 occurred at underground mines from a total work force of less than 2,000 miners. Nine of these 12 miners were fatally injured in falls of roof or rib. A safer environment for the miners can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground control strategies. Roof and rib conditions in the underground stone industry were observed and assessed at 33 mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania, and West Virginia [(Figure 1)]. Hazard assessment indicated that those ground failures occurring under moderate to substantial overburden (> 30 m [l00 ft]) were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine layout decisions tremendously influence ground stability.

Feb 24, 1997

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 R. N. Powell

The Pipeline ore body was discovered in March 1991. The construction of the new mine and mill did not start until early March of 1996. Upon completion of permitting and corporate project approval, the 289 million USD project was “fast tracked”. The commissioning began 11 months after start of construction and the project ended 40 million USD under the budget figure. The objective of this paper is to review and highlight the Pipeline Project history from discovery, design, lawsuits, permitting, and re-design through to current - 1998operating practices. Particular emphasis will review the process design, design mistakes, and design successes. The paper will review project history, feasibility, design concepts, operator training, construction, financial and the current operation. Additional discussion will review what design features worked and which did not work within the process plant.

Jan 1, 1999

In order to ensure safe mining and reduce surface damage in shallow multiple-seam mining, the failure characteristics of interburden strata with different coal pillar offset distances between pillars in the upper and lower seams, the distribution characteristics of stress concentration in coal pillars, and the development characteristics of stratum cracks and subsidence were physically investigated and also using UDEC2D software. Meanwhile, the effect of different coal pillar offset distances on the stress concentration of coal pillars and development of stratum cracks were studied. Based on those results, a formula for safe mining and reducing surface damage was established, which provided a theoretical basis for safe and environmentally friendly mining in shallow multi-seams. According to the results of the study, the optimal coal pillar offset distance (the side-to-side horizontal distance of the upper and lower coal pillars) between the upper and lower coal seams was developed to reduce the stress concentration of coal pillars and surface damage. The results of this study have been applied in Ningtiaota coal mine and have achieved good results in safe and environmentally friendly mining.

Jul 28, 2020

By James M. Riddle

A discussion of frequently asked questions may help individuals trying to interpret subsidence regulations or prepare permit applications. The subsidence permitting process involves just one part of the mass of Surface Mining Control and Reclamation Act regulations. But of the 18 main SMCRA sections, subsidence is critical to the permitting process for coal operators. It's an area in which applicants have had problems interpreting regulations and preparing permit applications. Of 22 western states, only Wyoming, Montana, Colorado, and Utah heave thus far received approval for their mining and reclamation plans. The other states are now involved in the permit application process and will be dealing with SMCRA regulations for the next year or so. Some state programs, when approved, may differ substantially from the federal SMCRA program. But, to be approved, the state programs must be deemed equal to or more stringent than the federal regulations. SMCRA regulations apply to any coal operation "that exhibits surface effects." Thus they apply to surface strip mines as well as underground coal operations. The regulations do not apply to hardrock mining operations. Since August 3, 1977, the government, industry, and the public have wrestled with SMCRA. They have struggled through an initial program with the US Geological Survey; a new agency, the Office of Surface Mining Reclamation and Enforcement (OSM); an interim program; and a "final" permanent regulatory program. Even now, OSM is reluctant to publish formal program guidelines because: •The regulations are still in the process of judicial review. • Some approvable state programs will supersede the federal regula¬tions. • The flexible regulations are open to interpretation, which is desir¬able to maintain. •Guidelines could be misleading until regulations and interpretations are revised and finalized.

Jan 12, 1980