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By John H. Archibald, Arthur L. Miller, George A. Savanick

As part of its continuing research on selective mining, the Bureau of Mines has made progress toward developing a tool capable of remotely extracting hard minerals through a borehole. As the successor to the successful borehole miner, which extracted soft materials through a straight borehole, this new device has several innovative features: 1) it can propel itself in and out of an 8-inch borehole; 2) it can cut hard rock with an abrasive jet and transport the cuttings to the surface; and 3) it can negotiate deviated boreholes--the feature that enables it to follow a vein and extract only the values. This paper describes the development and feature testing of the reamer/miner.

Jan 1, 1991

By E. Topuz, M. J. McPherson, I. M. Konduri

Theoretical investigations and laboratory experiments demonstrated that there is a great potential for the use of jet fan ventilation in mines. This paper summarizes research that consisted of laboratory-scale model tests, full-scale mine model tests and underground coal mine entry tests. The laboratory model used water as a fluid medium and simulated a typical 25-m- (82-ft-) long heading having a 1.5 x 6-m (4.9 x 19.7 ft) cross section. The effects of various nozzle positions and designs were investigated by using still photography. It was also found that the use of jets in combination with line curtains enhanced the overall ventilating effect in the model entry. Flow measurements in the full-scale mine model and in the coal mine entry were conducted to evaluate the effectiveness of the jet fan. It was concluded that the designed jet fan ventilation system was an effective means of ventilating blind airways.

Jan 1, 1998

By Randy Fulton, Ignacy Puszkiewicz, George H. K. Schenck

Stuart Olson Construction, Inc. excavated 385m (1263 ft.) long twin tunnels with 6.25m (20.5 ft.) O.D., a portal and a cross-over for the Edmonton, "Metro". The work for Contract No. 76458, SLRT South Tunnel and Portal, in Edmonton, Alberta, Canada was performed in 1989 and 1990. NATM was specified because of the instability of glacial deposits. The contractor decided to use "two firsts" on this project: Fully mechanized NATM and a novel excavator¬mounted tunneling machine. An excavator was equipped with a cutter boom, and a loading and conveying system. This novel machine cost only about one-third of the price of a special NATM roadheader. This new combination of NATM and an excavator-mounted cutter boom offered a cost-effective alternative to shields, slurry TBMs and roadheaders for short tunnels in unstable ground. For NATM tunneling in hard rock or in mixed faces, the roadheader-type cutter boom can be replaced with an impact hammer (hydraulic breaker).

Jan 1, 1993

By Georgene Renner, Chee Theng, William Gleason

"A walk through the exhibit hall or a glance at the technical programing that was offered at the 2019 SME Annual Conference & Expo and CMA 121st National Western Mining Conference in Denver, CO, Feb. 24-27 makes it evident that the mining industry is an innovative one that is on the cutting edge of technology. However, a glance at the nearly 6,700 attendees of the conference and it is also evident that while the industry is moving forward at a rapid pace in some areas, it is lagging behind in terms of diversity, both in gender and ethnicity.At Monday morning’s keynote session, Hannah Ubi, a millennial and a public speaker who joked that she is the proud owner of a sixth-place swimming trophy and a number of participation medals, addressed a full house that consisted of many men with gray hair or balding heads. The issue of an aging workforce that is rapidly being depleted by retirements is not a new one for the mining industry. In fact, it has been a concern for the industry for more than a decade. The central question has long been, “when the current senior-level people begin to retire, how do we replace them, and how do we fill the knowledge gap that is walking off into the sunset?” SME has been on the front lines in searching for solutions to the impending problem and, along with industry partners, has worked hard to develop programs that will address these issues. Among other efforts, the Society has developed a Ph.D. fellowship program to encourage people to remain in academia to teach the next generation and to help train the next generation to take over in the private sector.“The SME Foundation’s Ph.D. and Career Development Grant program is exceeding expectations at this point with two Ph.D. students graduating and taking a position in academia and two professors achieving tenure,” SME Executive Director Dave Kanagy said during the conference.The Society’s Minerals Education Coalition (MEC) has done its part to help educate future generations about the mining industry with initiatives like EngineerGirl, the Boy Scout Merit Badge and Move Mining, the Shark-Tank-style competition that was held on Monday with five finalists competing for the top prize (ME, April 2019, page 53)."

May 1, 2019

By Lennart Mukka

This paper describes the experiences from construction of a new ventilation system in LKABs Kiruna Mine in Sweden as well as the choice of the method for air flow regulation with concern of life cycle cost and the description of the foundation design. The evaluation of the performance test will be presented.

Jan 1, 1997

By J. M. Beck

Mineral property appraisers engaged in eminent domain actions on properties for which mining is the highest and best use must be fully competent in all phases of mineral resource estimation, mine project development, and mine operations (or retain the requisite competent assistance), as well as educated in eminent domain appraisal (USPAP Competency Rule). Failure to ensure such triggers the issue of appraisal competence and demonstrates a flagrant disregard of the myriad code(s) and guidelines to which the appraiser is subject. The cavalier assertion of some vague, undefined “latitude” in the valuation process does not exonerate the appraiser from a disregard of the USPAP Competency Rule. Lack of independence (i.e., “advocacy”) in mineral property appraisal is the usual result of a weak background in mining and/or appraisal theory. While it is readily apparent to those able to recognize it in reports and testimony, judges and juries cannot be expected to detect or recognize purposefully misleading (or even fraudulent) valuation concepts or testimony. Purposeful deception by the appraiser can lead to specious over-compensation of the property owner (thus victimizing the taxpayer); or, a failure to provide appropriate and just compensation to the property owner – yet, the purpose of an eminent domain proceeding is to leave the property owner no richer or poorer as a result of the taking. This paper highlights some of the deceptive practices encountered in litigation settings and raises issues of competency, professional ethics, and the effectiveness of the inherent enforcement capabilities within those institutions awarding professional certifications. INTRODUCTION The practice of eminent domain mineral property appraisal requires (particularly with respect to undeveloped mineral properties) that the appraiser possess the requisite level of competence in all phases of mineral resource estimation, mine project evaluation, mine development, and mine operation (through closure). To the extent the appraiser lacks such competence, it is incumbent on the appraiser not only to divulge this lack of expertise but also to seek competent assistance in the performance of the appraisal. This competence or expertise can only be obtained through a combination of appropriate and relevant technical education and direct mining industry experience. There exist a number of professional certification and/or credentialing authorities that speak to such competency. In a similar manner, eminent domain mineral property appraisal (as the term implies) also requires that the appraiser possess the requisite level of competence in the practice of eminent domain appraisal. This competence or expertise can only be obtained through appropriate and relevant education, direct knowledge of appraisal theory, particularly as it relates to the concept of eminent domain, and licensure.

Jan 1, 2019

I was very interested in Professor Park's data on subsidence over longwall panels. His paragraph labeled "Conclusion," however, does not seem appropriate for the article. Nothing in the article gives any discussion of how knowledge of subsidence characteristics can be used in mine design to minimize damage. That thought may have been a reason for undertaking this study, but not a conclusion of it. From his article, I would conclude that subsidence movements last considerably longer at great depth. And the National Coal Board's subsidence prediction model represents this area reasonably accurately, though most literature claims their model predicts far greater disturbances than actually occur in most areas of the United States. Also, I would like to know, is the method used to determine angle of draw? The criterion used can make a significant difference in the value obtained. With 30 m (100 ft) spacing and a 122-m (400-ft) depth the angle between stations can be up to 14°.

Jan 1, 1989

By R M. Whyte, D McArthur, A Macintosh

In designing a gold extraction circuit utilising carbon­in-pulp (CIP) technology a number of process options can be considered. These include various combinations of leach or pre-leach, CIP or carbon-in-leach (CIL) and conventional counter-current or carousel CIP (or CIL) circuits. Factors affecting the process selection include the project's sensitivity to capital and working costs, the project life, and the mineralogy and head grade. Each process option has it's own advantages and disadvantages. This paper compares both the financial and technical aspects of the flow sheet options. The flow sheet, design aspects and operating performance of Anglogold's West Wits No. 2 and 3 Plants which are leach, pump-cell circuits are described.

Jan 1, 2000

By MAURICE SUNKPAL, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

In this study, various rib bolting scenarios were investigated to better understand the effectiveness of the support systems. A coal mass constitutive model is implemented to a distinct element method (DEM) code, and rib factor-of-safety (RibFOS) analyses were performed by applying strength reduction for the coal matrix and explicitly modeled face cleats. Ribs with various overburden depths and mining heights composed of solid banded bright coal were considered. Different scenarios such as rib bolt length and number of bolts were studied to quantify the effect of primary rib support density on rib stability. As a result of the unsupported coal rib analyses, a decaying exponential relationship is proposed between the mining height-overburden depth and the RibFOS. The developed coal rib models clearly show the coal-rib bolt interaction and illustrate how the addition of rib bolts restricts the movement of the coal rib. The results reveal that the strength-reduction method in DEM code with the coal-mass model can aid in the development of practical primary sup- port charts, which can help in the rib support design process.

Feb 1, 2024

By Kristian E. Waters, Hao Ma, Haibei Wang

Heavy metal ions exist in waste effluents including mining tailings, manufacturing discharges, and smelting and metal plating process wastes. Various methods are available to treat industrial effluents containing high levels of metal ions, but when confronted with wastewater that has low metal ion concentration below 500 mg/L, most techniques suffer from low removal or separation efficiency as well as high operating cost. ELM-based techniques can be used to solve these problems.

Apr 1, 2023

By Francois E. Heuze

This paper summarizes the geomechanics programs conducted in two hard rock underground mining operations in the Western United States, between 1966 and 1981. The two projects were directed towards understanding the behavior of the rock masses, at the scale of the caverns. To this end, the emphasis was put on large scale field measurements, complemented by limited laboratory testing. The results of these observations were used to build realistic finite element models of the underground chambers. In the marble mine, at Crestmore, California, the models were applied to the structural optimization of the room-and-pillar pattern. In the granite mining, at Climax, Nevada Test Site, the models explained some unusual stress changes observed during excavation. Based on the large number of geomechanical techniques employed, specific conclusions and recommendations are offered regarding the quality, applicability, and usefulness of the various methods. The two case histories clearly indicate chat numerical models are extremely useful for a detailed understanding of the structural behavior of mine openings. To be realistic, these models must be based first and foremost on large scale field observations. The lessons Learned on these two projects also are directly applicable to the design and analysis of nuclear waste repositories in hard rocks such as basalt, granite, and welded tuff.

Jan 1, 1982

By J. B. Stockton, D. J. Robbins, E. T. Woodburn

Batch flotation data in an equilibrium cell show that beneficiation improves with froth drainage. The limiting lamella thickness in a well- drained 3-phase coal froth appears to be determined for ultra-fine particles (-45µm) by the d90 particle size. The froth stability is considered to depend on the existence of a very thin liquid film between the outer surfaces of the d90 particles and the bounding bubble interfaces of the lamella in which the particle is held. The dependence of the coalescence rate of bubbles in these froths on the residual surfactant concentration in the lamella liquid is then consistent with stability analyses for two-phase foams.

Jan 1, 1988

By R. L. Grayson, Y. J. Wang

An integrated approach to the management of underground coal mine production and cost is presented. A conceptual model for objectively analyzing an underground mine to obtain lower cost and higher productivity from operations is outlined. The model is designed to provide mine managers with a quantitative, decision-assisting methodology that can be used in formulating timely responses to fluctuations in operations. It consists of a productivity fore- cast component, routine use of current resource consumption factors, a linear programming scheduling component, a manpower loading analysis, and an inventory control component. The model is applied to an underground coal mine.

Jan 1, 1990

By Robert F. Jones

INTRODUCTION Upflow Solids Contact Clarification is a process long employed in the treatment of potable water, wastewater and municipal sewage. This process incorporated in a fiberglass conical structure seems to offer an economical solution to problems encountered in reduction of particulates in uranium effuents. CONCEPT OF UPFLOW CLARIFICATION Use of suspended solids contact units date back to the 1930's. These types of units produced by Infilco and the Permutit Company, among others, were used in the Lime-Soda softening process to precipitate calcium and magnesium salts from hard water. In general, the process operated as follows: (a) Raw water entered a central chamber where it was mixed with chemicals. The chamber had provisions for agitating and circulating the chemicals so that mixing and reaction zones were formed. (b) The water, precipitated chemicals, floc and turbidity flows to a clarification chamber (the Permutit precipitator used a truncated cone). In most cases the influent then passes upward through a blanket of suspended floc and other solids before it leaves the chamber at effluent weirs or launders.

Jan 1, 1984

By G. B. Johnston

I was very interested in Professor Park's data on subsidence over longwall panels. His paragraph labeled "Conclusion," however, does not seem appropriate for the article. Nothing in the article gives any discussion of how knowledge of subsidence characteristics can be used in mine design to minimize damage. That thought may have been a reason for undertaking this study, but not a conclusion of it. From his article, I would conclude that subsidence movements last considerably longer at great depth. And the National Coal Board's subsidence prediction model represents this area reasonably accurately, though most literature claims their model predicts far greater disturbances than actually occur in most areas of the United States. Also, I would like to know, is the method used to determine angle of draw? The criterion used can make a significant difference in the value obtained. With 30 m (100 ft) spacing and a 122-m (400-ft) depth the angle between stations can be up to 14°.

Jan 1, 1990

By S. L. Crouch

The general term "coal mine burp" refers to the sudden and violent failure of in situ coal. Coal bumps occur in most countries where coal is worked by underground methods, and are related to both geological factors and mining tech¬niques. Although no single set of circumstances is solely responsible for causing coal bumps, it is generally agreed that at least one of five conditions is necessary in order for then to occur: 1,2,3,4 (1) the depth of cover exceeds 500-ft., (2) the overlying strata are relatively strong and stiff, (3) the coal is structurally strong, (4) the floor does not heave readily, and (5) the mining method produces high stresses over a large area of the seam. Except for the last, these conditions relate to geological factors that are impractical to control. Consequently, methods of controlling or minimizing the occurrence of coal bumps usually are concerned with mining techniques. Coal bumps have been successfully controlled by both longwall and 'yielding pillar' mining systems 4. The longwall system is particularly effective in controlling bumps, but does not eliminate them completely, especially in strong coal seams being worked at comparatively great depths, say in excess of 2000-ft.5. Under such conditions, auger drilling or water infusion often prove helpful 5,6. These techniques are used to destress or otherwise alter the mechanical properties of the coal in an attempt to shift the peak "abutment pressure" away from the immediate vicinity of the face. Under 'normal' conditions, however, it can be expected that the coal near the face will be crushed under the prevailing high stress conditions and that the peak abutment pressure will automatically be shifted into the solid coal. In this context, coal mine bumps can be characterized as unstable releases of energy associated with successive yielding of portions of the coal seam with progressive mining. Longwall and yielding pillar mining systems are effective in controlling coal bumps because they ordinarily do not allow the zone of peak abutment pressure to become 'surrounded' by destressed coal.

Jan 1, 1973

By Inoka E. Perera, Michael J. Sapko, Marcia L. Harris

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effectively inert a coal dust explosion, rock dust must be able to disperse as individual particles to air. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anticaking additives after being exposed tomoisture and then dried. The dusts were exposed tomoisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anti-caking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Experimental Mine (LLEM), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for 1 day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for 6 months. This report details the analysis and characterization of anticaking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber.

Apr 12, 2021

By C. Y. Chen

In order to put an end to the uneven environmental standards and enforcement established by various coal mining States in the United States, the Congress passed and the President signed the Surface Mining Control and Reclamation Act (Public Law 95-87 or the Act) on August 3, 1977. Within one year after passage, the Secretary of the Interior was directed to promulgate permanent program regulations implementing Title V provisions of the Act. These regulations were to form the basis for State regulatory programs under the Act and to allow States to assume primary regulatory responsibility. In order to implement the underground mining provision of the Act, the Secretary is directed in section 516(a) of the Act to promulgate rules, but ones which take into consideration the distinct differences between surface coal mining and underground coal mining. The regulations developed by the Secretary and promulgated on March 13, 1979, with respect to subsidence control, included (1) a subsidence control plan as part of the permitting process, (2) substantive provisions establishing performance standards for subsidence control, and (3) provisions providing for the prohibition of mining under perennial streams, impoundments larger than 20 acre feet, and certain public facilities and urban areas.

Jan 1, 1985

By Peter J. King

Demand for both lead and zinc to the year 2000 will be characterised by modest to nil growth in mature economies, with positive 3 to 4 per cent annual growth rates in developing nations. Asia and China will feature significantly in this growth. Overall lead demand is expected to grow about 1 per cent a year, with industry becoming more dependent on the fortunes of the automotive industry as the lead-acid battery will be the only major end use to expand. Zinc will become more dependent on its main use, galvanising, as the automotive and construction industries move to high levels of dependence on corrosion prevention. Strong growth in zinc consumption in S.E. Asia, China and India is likely to feature widespread development of the continuous steel strip mini-galvanising line technology. Thank you Mr. Chairman for inviting me to this Conference. As an Australian I am honoured to be here to offer some thoughts about future trends in metal consumption -- with particular reference to the role of countries in my own neighbourhood, the developing Asian nations, including China. It is customary for a member of the producer fraternity to speak to the topic of future development. This is no doubt due to the fact that our companies are so often engaged in endeavours to determine the future prospects of the metals as essential background to massive investment decisions relating to the development of new mines and smelters. This is sometimes also applied in relation to the more painful decision of closures of aging operations. In this paper I have drawn upon recent studies by AM&S into the future of lead and zinc. While this work has been thorough and skillful, we are nonetheless left with uncertainty on a number of counts. Firstly. predictions in the past in our industry have not been all that credible. Need I remind a U.S. audience for instance of the Paley ' investigation setup by President Truman in 1950 to study U.S. copper requirements for 25 years in the future. Asarco's Simon Strauss gave those of us daring to forecast long term commodity trends a salutary reminder that the Paley Commission with all the expertise at its disposal missed the mark in its copper predictions by a very wide margin indeed. Additionally, it is difficult to take comfort from longer term economic forecasts. Too many important economic issues remain unresolved suggesting considerable caution. These include the threat of growing protectionism; low economic growth rates with stubborn unemployment levels; and levels of government expenditure at near saturation as a percentage of GDP, to name a few. However, on a more optimistic note. we can look to China, where there appears to be momentum in its economic growth; oil, where stable oil prices to the mid 1990's will contribute to inflation control; and the fact that LDC debt, while still a major issue, is declining in importance and priority. In the short time allocated to us. I wish to deal succinctly with the lead and zinc raw materials supply picture, which is one I do not believe will hold too many surprises for this audience. Following the review of raw materials supply, we will turn our attention to the changes in the pattern of demand towards the year 2000. emphasising the Asian position. In this context. I would like to focus on the theme of the changes in OECD consumption levels relative to those of the emerging nations. One area we will be paying special attention to is China.

Jan 1, 1986

By J. L. Thompson

The combustion of pulverized coal is a century-old practice. Many people have investigated coal dust and the residual fly ash particles that re-main after combustion. But the combustion process and fly ash formation mechanism are not under-stood. Working at our Maysville, Kentucky lime plant, the Dravo Lime Company Research team has collected samples of partially burned coal dust from the flame of a pulverized coal burner. Specimens were placed in a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Microscopic examination of the particles, together with a large collection of micrographs of lime dust fused to fly ash particles, now make it possible to theorize as to how combustion advances through a piece of coal dust. Coal is a physical mixture of carbon-based compounds interspersed with bits of ash-forming materials, primarily alumina-silicate compounds. The alumina-silicate materials are commonly in angular nodules measuring 100 A to 700 A across their major dimension. It would appear that if the coal particle is in a well mixed gas stream, combustion starts at the surface and advances radially toward the particle center. With poor gas mixing, it is common that combustion moves from one end of a particle and advances on a broad front almost normal to some axis. In either case the combustion process and ash-forming mechanism are the same. As combustion occurs the carbon-based compounds oxidize in a highly exothermic reaction. Heat from the re-action melts the alumina-silicate nodules causing them to flow together and coalesce into an open sponge-like structure. As melting continues surface tension of the liquid and free surface energy causes the sponge-like structure to simplify into fewer, larger pores. Most likely the lighter molecular weight hydro-carbons burn before the heavier species. This means that as the melting ash structure is metamorphosing to a single large pore, there continues to be out-gasing throughout the structure due to combustion. Surface tension will form a spherical piece of fly ash if the ash material is liquid for a sufficient period of time. Out-gasing from combustion of the heavier hydro-carbons will provide internal gas pressure to keep the particle spherical until it freezes.

Jan 1, 1978