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By A. H. Baldo

Covers a very broad spectrum of problems and solutions. The problems are multitudinous and their solutions are sometimes simplistic, sometimes ingenious and sometimes within a very broad interpretation of the law. However, one thing is quite certain: the problems and their solutions will have a direct impact upon corporate and personal well being. First of all, why does one mine in a foreign land? Since the Bronze Age, when ancient man discovered the metallurgy of copper, tin and zinc, intrepid souls have been wandering afield searching for and exploiting those mineral deposits which would create wealth and security for his city-state or community.

Jan 1, 1981

By Christian F. Baiz

A new agenda has risen. Born out of governments' policies and world economies, the years ahead will carry with them reduced growth. For inflation dependent and capital intensive industries, such as metals and mining, as well as most other natural resource industries, a period of long-term contraction in outmoded and costly capacity will evolve. This will be supplanted by new, lower cost capacity in some cases, but only if the total cost of production, including cash operating and debt service costs comes in at or below current market conditions. The industrial outlook can be characterized as bearish. As one major U.S. bank economist put it, mining companies planning their five-year forecast from 1984 out, should take the current market conditions and straight-line them to the end of the decade. With low growth and low inflation, the real price of metals will remain flat or slightly declining. As a result, capital funding will be problematic. The low cost producer, that is one with low cash costs and low principal and interest costs per unit of production, will succeed.

Jan 1, 1984

By Robert A. Pimentel

Dust is still a major problem in increasing production from longwall faces. Over the last decade, significant improvements have been made in the development of techniques for reducing dust exposure on conventional and continuous sections. But virtually no improvements have been made in dust control on longwall sections. It is true, that there are many more continuous mining sections than longwall sections in the United States and that the number of workers overexposed on continuous miner sections is much larger than the number on longwall sections. However, the problem on continuous miner sections appears much easier to solve and, in fact, we believe that the techniques are available to get virtually all continuous miner sections in compliance. The problems on longwall sections are much more elusive. Also, the number of longwall sections in the United States is expected to increase during the 1980's. Thus, dust control on longwall sections remains a formidable and important problem. Companies operating longwall sections with a dust problem are faced with the tasks of having to quantify the various dust sources, of selecting proper techniques to reduce the problem, of implementing the techniques and of evaluating their effectiveness.

Jan 1, 1983

By S. A. Shoop

Vibrations from thirty-seven blasts were monitored using three seismographs. Data analysis showed that square root, cube root, and site-specific scaling predicted ground motion with equal reliability. Imprecise prediction is caused by geologic and blast variability, particularly inaccurate delay times. Vibrations at some mines were consistently lower or higher than vibrations reported in the U.S. Bureau of Mines studies. Regulations based on USBM data could then be too conservative or lenient. Predominant vibration frequencies were generally less than 50 Hz, but several blasts had significant energy up to 125 Hz. In some cases energy was concentrated at frequencies corresponding to delay intervals.

Jan 1, 1983

By Robert M. Jimeson

The competitive market potential for solvent refined coal is estimated. Market advantages of solvent refined coal are enumerated. Markets are possible in combustion, railroad locomotion, and carbon electrodes. The combustion characteristics are consistent with expected air pollution restrictions on the emission of sulfur and particulate matter. A market potential of sufficient size exists to support the initiation of solvent refining in the United States. The market analysis should help fuel producers determine the advisability of their undertaking the solvent refining of coal.

Jan 1, 1969

By Thomas W. Turk

The water treatment industry has historically been involved with reducing or inhibiting the inherant scale forming or fouling tendencies of natural waters associated with large industrial cooling water systems. Fouling is an extremely complex phenomenon. From a fundamental point of view, it may be characterized as a combined momentum, heat, and mass transfer problem. Chemical reaction kinetics is involved, as well as the solubility characteristics of salts in water and corrosion technology. It is a routine practice to over size pumps, piping and heat exchangers to compensate for fouling.

Jan 1, 1983

By C. E. Capes

The continuous balling? operation whereby a moist particulate mass is tumbled in a horizontal revolving drum with recirculation of the undersize product can be extremely unstable. Product and recycle rates are subject to wide fluctuations. Although the problem seems to be well-recognized, there is little published information or quantitative data readily available, especially in relation to industrial-scale circuits. Probably the best available published results are in the Russian literature, an illustration of which is given in Figure 1. These data, taken from a study') of some of the factors which influence the stabilization of the pelletizing process, illustrate the wide variations in circulating load and circuit productivity which may be encountered over a period of operation. The problems of balling circuit stability may be traced to random seed or nuclei generation and uncontrolled agglomerate growth. The situation is analogous to that in crystallization processes where (4 considerable attention is given to nucleation control. Traditionally attempts have been made to optimize system and operating variables to stabilize the balling process. A supplemental approach which is taken here is to build on the considerable

Jan 1, 1975

By A. F. Grandt

What is prime farmland? Can such land, once it has been strip-mined for coal, be restored so that it will produce corn, soybeans, wheat, and alfalfa? What methods or practices are necessary to bring about restoration within a reasonable time so that crop yields will be equivalent to or higher than those of unmined prime farmland under high levels of management? These questions concerned land use researchers in Illinois as early as 1948 when the Illinois Agricultural Experiment Station experimented with growing cultivated crops on strip-mined land in St. Clair County (1). This research was done almost 30 years before requirements of Public Law 95-87 were passed by the United States Congress and signed August 3, 1977.

Jan 1, 1980

By W. M. Luff

The Brunswick No. 12 Deposit is a large polymetallic massive sulphide deposit, occurring in Ordovician age rocks of the Tetagouche Group. Silver is contained within the sulphide zones and economically it is the second most important commodity produced. Brunswick is one of the largest silver producers in Canada. The distribution of silver within the mine is presented, with examples from various levels. The concentration of silver can be shown to be related to both stratigraphy and structure. The mineralogy of silver in mill products is also presented.

Jan 1, 1986

By Yoginder P. Chugh

Effects of moisture absorption on the behavior of the Dykersburg shale overlying Harrisburg coal seam in Southern Illinois are presented in this paper. Cylindrical samples of the shale 2.5 cm in diameter and 5.0 cm long were studied for weight gain and swelling strains at 90, 95, and 100 percent relative humidity and under immersed water conditions. After attaining equilibrium conditions, the samples were studied for changes in the strength and deformation behavior. The depth of moisture penetration was measured using the Vickers microhardness measurements. Using the basic mass transfer concepts, effective diffusion coefficients were computed for the shale.

Jan 1, 1980

During the past year a number of significant advances in geostatistics have been published. These were presented at the 13th APCOM Symposium in Clausthal, Germany and at a NATO Advanced Study Institute on Geostatistics in Rome, Italy. Of greatest importance is the work that has been done in establishing methods which correctly predict the cutoff grade-tonnage curves, and the average grade of ore-tonnage curves for deposits in which ore and waste are intermingled. Grade-tonnage curves based on estimates made from widely spaced exploration data have been found to underestimate the grade of ore and overestimate the tonnage present. This problem has been remedied by the calculation of conditional probability distributions for the unknown grade of a block. Another advance has been made in the field of geostatistical estimation for deposits in which a trend is present. Previously a technique known as universal kriging has been used, which involves much subjective judgement as to the trend fitted. A new technique, generalized increments, allows computer estimation of such deposits with much less subjective judgement. Computational efficiency of geostatistical methods has continued to improve to a point where a geostatistical estimate can be obtained for little more than the cost of any other computerized method.

Jan 1, 1976

By T. Vandergrift, J. Sturgill, W. Gerhard, J. Carrick

As surface minable coal is depleted, many operators look to high-wall mining to extend reserve life. Recent advances in highwall mining equipment have greatly improved productivity, clean coal recovery, and attainable penetration beneath the highwall. Somewhat lagging have been systematic design approaches for ensuring web pillar and overall highwall stability. This paper presents an overview of the design, planning, and field performance of a multiple-seam highwall mining application in southwest Wyoming. The safety and efficiency obtained to date is attributable to the careful geotechnical and operational planning described herein. Field confirmation of performance and suggestions for improvement are also discussed.

Jan 1, 2004

By F. Varley

Researchers from the National Institute for Occupational Safety and Health (NIOSH), in cooperation with mine operators, conducted a study of heat stress exposures among mine rescue workers in underground mines. Mine rescue workers face extreme heat loads as they enter hot and poorly ventilated environments, particularly when they are wearing breathing apparatuses. The burden of wearing a closed-circuit breathing apparatus (CCBA), the inability to drink fluids for extended periods of time, and the potential for ventilation disruptions and fires combine to increase the risk of heat illness during a response to an emergency. In this research, ambient environmental conditions and heat strain indicators were measured using conventional ventilation monitoring tools during mine rescue training exercises. Heat strain was measured with an ingestible temperature-sensing pill that measured core temperature continuously. In addition, a heart-rate monitoring chest strap was used to indicate physical strain resulting from physical activity and heat. Both core temperature and heart rate data were trans-mitted to a remote recorder worn by a rescuer and time-stamped. Team activities were also observed to determine the contribution of work rate to a person’s total heat load. The effectiveness of several engineering controls, such as cooling the air inhaled by rescuers through an apparatus, wearing cooling vests, and supplying water through the CCBA masks, were investigated. Administrative controls, such as limiting the duration of exposure and controlling the work rate through forced-rest regimens, were also evaluated. Results to date are discussed, and tools for evaluating team condition and estimating the length of time it would be safe for rescuers to work are proposed.

Jan 1, 2004

By R. W. Bartlett

I first met Milton Wadsworth in 1951 as an eighteen year old junior taking his mineral processing course at the University of Utah. He guided my senior thesis, evaluating the then new polymer flocculants on settling uranium leached ore pulps. This was before ion exchange and solvent extraction. After my military service and a brief working stint at Kennecott he supervised my PhD work. He encouraged me to be active in AIME and its constituent societies, where both of us have been directors of AIME and presidents of TMS. He has been a consultant for research groups that I have managed. Above all, he has been my mentor and friend for nearly 45 years. Thus, I am honored and particularly pleased to receive 5MB's Wadsworth Award.

Jan 1, 1996

By R. A. Ynchausti

In January 1993, Pyramid Resources began implementation of a supervisory expert control system at a U.S Cu concentrator. The objective of this control system was to improve plant profitability through unit operation optimization and integration. This paper documents the key aspects of the project, including: economic and associated benefits, system architecture, concepts of implementation, process control strategies, practical aspects of implementation and conclusions. The implementation of expert control at this concentrator has resulted in an estimated benefit of $50,500 per day. This is a net result of improved tonnage, reduced reagent consumption, improved concentrate grade and reduced energy per ton produced.

Jan 1, 1995

By Takayoshi Otsuka, Taher Elsamni, Ashraf Bou-Krisha, Takaya Takimoto

"INTRODUCTION Tunnel is a closed space structure and it is necessary to ensure the sufficient time and route for safe evacuation for the tunnel users in case of a tunnel fire. In order to do so, damages and collapse of the tunnel linings and the secondary disasters can be avoided. Furthermore, the road tunnel is one of important infrastructural facilities and stopping its function for a long time for a tunnel fire could cause a great economic loss. Therefore, the tunnel structure shall be the one which can be repaired as soon as possible, and the fire protection methods need to be selected among those which enable the service to start as early as possible. The necessity of the fire protection works is evaluated for the tunnel structure with the consideration of the expensive tunnel construction cost and the economic effects of the tunnel service. Naturally, the fire protection works, which can protect the tunnel linings from the tunnel fire with small repairs, are inevitable. Design engineers of the fire protection works estimate the scale of fire from the degree of damages on the linings and its repair cost, the effect of fire extinguishers placed inside of the tunnel, the secondary disasters in accordance with the tunnel lining damages if any, and the ratio of fire protection cost calculated from tunnel operation cost. Based on this information, the engineers design the fire protection works according to the permissible limits Among the design cases of the tunnel fire protection in Japan, as shown in Table 1, there is no cases that used the fire temperature-time curve to design the fire protection works for large fire caused by vehicles catching fire. However, the most of cases used 30-60 minutes for fire duration based on the entry prohibition of dangerous goods carrying vehicles or the effect of early fire fighting. This paper will study the variation between different methods used for fire protection in road tunnel in Japan to evaluate them and try to found some recommendations. Especial l care will be attention to Polypropylenes (PP) which is starting to be applied lately."

Jan 1, 2016

By Y. Topkaya, R. E. Johnson, D. Buttinelli, B. R. Palmer, A. Geveci, L. Stoppa, C. Lupi, F. Pochetti

Representative samples of a composite mixture of three typical Cu/Zn complex sulphide ores, namely Black-, Yellow- and Altered-ore, from the Cayeli deposit in Turkey, were used for leaching tests in 2.2 M FeCl3, or 1 M CuC12-2 M NaCl solution in the temperature range from 313 K to 363 K (40O to 90O C), with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high, as expected, in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature when the solvent was present. However in CuC1, solution, extraction yields of the order of 95% only for Cu and Zn were achieved and the positive effect of the solvent was not clearly shown. The kinetics curves of Cu leaching by FeCl3 indicated a model of reaction rate depending on the particle surface, as in a chemically controlled reaction, in tests with the presence of CCl4. Without the solvent, or in CuCl2 media, the model of the diffusion controlled reaction seemed to prevail. Values of apparent activation energy, in both of the leaching processes, were determined and compared with those reported in literature.

Jan 1, 1993

By K. R. Griffin, K. D. Luxbacher, E. C. Jong

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background-oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera’s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

By Shiou-Chuan Sun

The froth flotation of coal, differing greatly from that of most minerals1-5, is not improved but rather impaired by temperatures higher than room temperature6-10 This phenomenon has long taunted us for an explanation. Gayle and Associates 8,9 reported the lack of relationship between their contact angle measurements and their flotation of American coals under various temperatures. Bailey and Whelan6 stated that the viscosity of flotation reagents, offering some clue for their flotation of British coals at low temperatures, could not be put forward as an explanation either in whole or in part for the effect of temperatures on coal-flotation. In this paper, a froth hypothesis is proposed to explain the flotation behavior of coals under various pulp temperatures. Test work involved the flotation of coals and the frothing of reagents.

Jan 1, 1966

By Welland L. Ott, Hans J. Rumland

The Falconbridge Dominicana laboratory receives samples from all parts of the operation. Ore, metal and oil samples are taken by operating departments, gas and water samples by the laboratory staff. Physical sample preparation is essentially standard and produces comminuted samples for wet-chemical analysis and X-ray fluorescence analysis (XRF). T he main operating sections of the laboratory are described indicating in each case the type of instrumentation and method used, sample types analysed and comments on problems experienced. Emphasis is given to the sample preparation and X-ray sections especially with regard to the difficulties caused by our heterogenous ore material, calibration of the instrument and operational malfunctions. General problems related to our remote location and the tropical climate are discussed. Limited statistics on instrument availability, and stability, accuracy, precision, etc., are given.

Jan 1, 1979