Search Documents

By S. Dempsey

Since its passage in 1872, the Mining Law has been modified on several occasions to meet the changing needs of America's society and economy. Despite its evolution, the Mining Law continues to be criticized as outdated. This paper briefly traces the major points in the history and evolution of western mining laws, and reflects on the current status of ongoing discussion to reform the 1872 Mining Law.

Jan 1, 1997

By David B. Cook, James R. Bieke

I. INTRODUCTION Lawyers are a cautious breed; and it might be expected that a paper concerning a broad and complex area of legal regulation, prepared by lawyers for presentation to a predominantly non-legal audience, would commence with several caveats. Ours are the following: First, we have written a broad (and, in some instances, simplified) overview of the regulatory system and of some of the more important requirements generally applicable to uranium mine and mill wastes in the United States. Our paper is not a legal opinion setting forth all of the governmental requirements that would have to be met by any particular mine or mill. Similarly, we do not imply that the requirements we mention are necessarily applicable to each and every mine and mill in the country; depending on the facts, some of the requirements may be inapplicable or avoidable through exemption or variance proceedings. Compliance decisions and strategies for particular facilities must be considered on a site-specific basis. Second, we have undertaken merely to describe the regulatory framework and some of the generally "applicable" requirements which have been promulgated and proposed by administrative agencies. We express no opinion on whether, under the U.S. Constitution and statutes, the existing and proposed agency regulations are valid in general or as applied to any particular mining or milling operation. There are, of course, procedures for judicial review of agency action; and newly promulgated environmental regulations have frequently been challenged, with varying degrees of success, before the courts. For us even to begin to consider such issues would expand an already forbiddingly long paper to totally unmanageable proportions. Third, in light of the subject of this Conference we have limited our paper to the legal framework and requirements applicable to uranium mine and mill "wastes" -- primarily mine overburden and waste rock and mill tailings (including waste tailings solution). We treat operating discharges (e.g., emissions from yellowcake drying) only peripherally. Fourth and finally, it is important to note that this paper, at least in so far as it concerns the specific requirements of particular regulations, will likely soon be out of date in some important respects. Despite

Jan 1, 1980

By Pan Eimon

She was young, beautiful, intelligent, virgin. Her name was Barbara and she captured the attention of many men, especially those in dangerous occupations. Her rich and doting father was hopeful of making an advantageous marriage for his daughter. Instead, she defied him, became a Christian, and refused to marry. Traumatized, he killed her and was himself struck dead by lightning. That is not the plot of a new soap opera. It is the melodramatic story of a Turkish teenager who was martyred in the third century but lives still as patron saint of mining. The story begins with a 20th century fact. Santa Barbara is a figment of imagination - perhaps based on an early oriental folk heroine, embroidered by a seventh century storyteller, and reworked by a ninth century Greek martyrologist. The authoritative Lives of the Saints reports: "There is ... Considerable doubt about the existence of a virgin martyr called Barbara and it is quite certain that her legend is spurious. There is no mention of her in the earlier martyrologies, her legend is not older than the seventh century, and her cult did not spread until the ninth." The Catholic Dictionary adds that the Barbara story is probably "a pious legend." Widely revered Santa Barbara was one of the most widely venerated saints of the Middle Ages. She became the patron, not only to miners, but also to artillerymen, engineers, architects, builders, stonemasons, gravediggers, and sailors. Mines, mountains, churches, and places bear her name. Barbara's feast day, Dec. 4, appears on the most ancient holy day calendars. And a Barbara festival is still celebrated throughout central Europe, in Spain, and in mining areas of Latin America on that date. The Pacific coast channel, the city, and the mission of California are named for Santa Barbara. An expedition, sailing that coast under Viscaino in 1602, was saved from shipwreck on Dec. 4 after the sailors prayed for Barbara's intervention. Franciscans gave her name to the modern Franciscan Province of Santa Barbara, which embraces six western states and the Philippine Islands. Barbara is intimately entwined with mining. The origins of both saint and profession are lost in an-

Jan 11, 1985

"One of the major issues that the Rare Earth Elements Mining Industry has to deal with is the legislation vacuum that exists in many countries around the world. Among these, are countries which have long history and tradition in mining. In many cases the lack of direct legislation for REE mine management as well as for other potentially polluting industries can be a barrier to sustainable development. Moreover, the case of lax legislation in China has led to environmental pollution problems and extended smuggling of rare earth elements. This paper looks into the current regulatory status on the mining of REEs, identifies the loopholes and suggests some elements for a new global legislation framework for sustainable development in the REE mining industry. The setting of this regulatory framework will be in line with the present and future challenges of the rare earths market as well as with the policy strategies that are defined internationally. The aim of such a legislative framework will be to strengthen the global rare earth elements supply chain, appease social concerns and ensure the preservation and conservation of the environment. INTRODUCTION The general public received their first introduction to rare earth elements (REEs) in 2010, when the previously inconspicuous commodities became the subjects of front-page headlines. It was when China created a furore in global high-tech markets after imposing an embargo on Japan following a minor marine dispute (Barakos et al. 2015b). Soon enough the Chinese embargo was extended on REE export restrictions all over the world and thus aroused concerns to many countries over potential supply disruptions. The world had suddenly realized that these wonder materials underpin products that they care about. Governmental and industry executives, policymakers and material scientists voiced concerns and conducted numerous reports stating the situation and the risks of a supply crisis. The price spike of 2011 intensified the crisis and the public turmoil, yet the drama did not last for long as the prices declined significantly in 2012. Nevertheless, the world was nonplussed by the fact that China has the total control of the market with more or less the 90% of the global production. More potential entrants became interested, thus initiating an exploration boom during the recent years that has resulted in a significant increase in known global REE reserves that could have potentials for exploitation."

Jan 1, 2016

By Steve Kral

The mining industry has waited a long time for the resurgence in commodity prices and demand for its products that it is now experiencing. Base and precious metals prices have reached levels not seen before. Coal prices have also shot up. And there are encouraging signs in the uranium market. China’s nearly out-of-control economic growth is said to be the leading driver for much of this resurgence. But demand for energy, metals and building materials in the United States and elsewhere are also major factors. The result is that expansions and new mines for nearly every commodity are in the works.

Jan 1, 2005

By M. Heger

February 2, 1999 marks a milestone in earth-moving technology at the San Miguel Lignite Mine. It was on that date that The North American Coal Corporation (NAC) took delivery of three Leica Dozer 2000 GPS grade control systems for use on its bulldozers. The primary reason for the purchase of these grade control systems was to prove that GPS technology could safely and economically be utilized on heavy equipment to assist operators in defining grades. If these properties were successfully demonstrated, the ultimate vision of the project was to expand the system to a point were GPS would become the primary means of providing grade control information to the mine’s heavy equipment operators. Twenty nine months and more than $500,000 later this vision was realized when the final bulldozer operating at the San Miguel Lignite Mine was equipped with Dozer 2000. Presently North American Coal has a total of nine Dozer 2000 GPS grade control systems at San Miguel providing cut and fill information to operators 24 hours a day. These grade control systems have allowed the San Miguel operation to increase safety, reduce costs, improve operator attitude, and better ensure environmental compliance. This article discusses both the nature of these benefits and some of the issues that had to be dealt with along the way.

Jan 1, 2002

By J. B. Gwiazda

S.S. Peng The highlights of this paper are: The shield supports with lemniscate links will exert a tangential force on the roof strata, causing unnecessary and harmful roof movements, thus damaging the roof structure. The principal source of the tangential force is the horizontal movement of the point O, the pivotal joint between the canopy and the caving shield. When the support height is changed during setting, the point O will move along a curve upward and rearward toward the gob. As a result, it produces a vertical movement, causing the roof to move up a distance of t d, and a horizontal movement toward the gob, creating vertical fractures in the roof. The major purpose for employing the lemniscate- link system is to protect the hydraulic legs against the action of the bending moments induced by the tangential force that causes deformation or destruction of the legs. Based on these two points, the author suggested that, in order to eliminate the harmful effects of the lemniscate-link system and strengthen its advantageous features, a shield support with a new design of that mechanism has been developed. With the new design, the conventional rigid lemniscate links are replaced by hydraulic rams. When the pressure inside the rams reaches a certain level, the ram will yield.

Jan 1, 1987

By S. Budirsky

J.B. Gwiazda's article deals with an interesting problem that has not been studied thoroughly up to now. Gwiazda has proposed a technical solution that eliminates horizontal load imposed by the supports on the roof. That load is due to a discrepancy between the trajectories of the canopy and the overlying strata. It is true that the improved lemniscate guidance system proposed by Gwiazda could eliminate the horizontal load but, on the other hand, it would represent a higher cost of the supports, and it would complicate the already complicated mechanism of powered supports. That is why we must be convinced that the proposed improvement is actually needed. From that point of view, the following questions should be elucidated. As shown in Fig. 1, the point O travels along the curve a, which produces horizontal load on the roof in the direction of the coal face. As stated by Gwiazda, "such a high load is capable of destroying the roof above the support, causing rock debris to be scattered around the face." The results of our measurements carried out in coal mines of the Czechoslovak part of the Upper Silesian Coal Basin show that the convergence in the modern type of powered supports does not exceed several millimeters (not more than 10) per hour. Similar conclusions were drawn from field measurements performed in the Polish part of the Upper Silesian Coal Basin (see S. Romanowicz and H. Szopka in Proceedings, Scientific and Technical Symposium Simmex '85, Katowice, Poland, pp. 73 -83). The small vertical closure of the supports also induces a small horizontal displacement of the canopy. In addition to this, the transmission of forces between the roof and the canopy is influenced by the layer of debris on it, i.e., the canopy slides without imposing a greater horizontal load on the roof. This was deduced from field measurements of Voest-Alpine F 4/4600 powered supports equipped with rams instead of the common front lemniscate links (denoted as 1 in Fig. 5). In these supports, the pressurizing of the space of piston rod (la in Fig. 5) causes the rams to close, which induces horizontal load on the roof in a direction toward the coal face. After the setting of a support unit, the pressure in the piston rod space was found to drop, frequently to zero, because the small horizontal sliding between the canopy and the debris or inside the debris caused the horizontal reaction from the roof to fall to zero, although the debris were pressurized by vertical setting load. As a consequence, there was no horizontal load imposed by the canopy on the roof. A rise of the horizontal load was recorded only after the passage of the shearer and during lowering of the adjacent units. Thorough information on the results of the afore- mentioned field measurement is given in the paper, "Analysis of the performance of shield powered supports installed in a thick seam," published in Mechanizacja i automatyzacja gornictwa, 1982, No. 12, pp. 38-46. An English translation of the paper is available from the author. We have deduced from our observations that horizontal load imposed by the canopy on the roof in the direction toward the coal face is useful for roof control because it limits the displacement of the immediate roof toward the gob particularly during the rise working. We came to the conclusion that horizontal load on the roof toward the coal face should be induced on purpose. Could Mr. Gwiazda prove with the results of field measurements his contrary opinion? Has the small horizontal displacement of the canopy toward the face actually had an adverse effect on the roof? As shown in Fig. 2, during the setting of a support unit, the canopy imposes a horizontal load on the roof in the direction of the gob. In this case, I share Gwiazda's opinion that the horizontal load could have an adverse effect on the roof. Nevertheless, two important circumstances were neglected - the horizontal compliance of the supports and the interaction of adjacent units. The question of the compliance was analyzed precisely by I. Krumnacker in Gluckauf -Forschungshefle, 1984, NO. 5, pp. 219-223. He found that due to the clearance between the hinge pins and the eyes of the sheild and due to the elasticity of the steel structure,

Jan 1, 1988

By J. B. Gwiazda

In regard to the paper by J.B. Gwiazda, it makes a highly technical approach to show that the .u factor used by designers of lemniscate-guided roof supports has never really been confirmed as a maximum and assumes that convergence is vertical. Also, the paper does not appear to take into account deflection of structures, which occurs when the lemniscate and base members are fully loaded to their maximum stress level, nor the front to back line of the support in relation to differential roof to floor movements caused by strata movements under pressure. It is not unusual for differential movements to be slightly diagonal to the line of the support, particularly in faulted areas and on gradient faces. The paper also does not take into account consolidation of fines immediately above and below the support. Generally speaking, any differential movement is from face to waste and under these conditions the .u of 0.3, which appears to be an international standard, has worked in practice. However, if the face end of the support is lower than the waste end, then the µ of 0.3 can be considerably increased, giving rise to the damage mentioned in the paper. The ideal design should aim for a slightly forward bias in the lemniscate guide so that the last increment of setting is toward the face, tending to close any fissures that may have developed during the support advance cycle. The support should also be fitted with positive set valves to ensure that a high setting load density is attained to minimize bed separation. As far as powered supports are concerned, convergence is irresistible and all powered supports converge at their rated yield load. A similar principle can be applied to the differential roof to floor movements to drastically reduce the very high forces that would otherwise be applied to the lemniscate structures and pins and that, in turn, are transferred to the base arrangement and floor loading. Any differential movements are usually catered for by the 0.3 µ factor or deflection of structures in the lemniscate guide arrangement and consolidation of the floor. The floor loading, due to differential movement, is in addition to the support convergence load and requires additional bearing area to avoid possible floor penetration. Some seven years ago, Fletcher Sutcliffe Wild Ltd. (FSW) introduced a lemniscate-guided shield support where the lemniscate linkage is connected to the roof bar through two horizontally converging rams to allow differential movement to take place above a given rated figure. This is a known force and can be guarded against, whereas with rigid connections the forces, as yet, are unconfirmed. By careful design, a horizontal force in excess of 6 MN (60 tons) opposes differential movements for a total ram loading of only 2.5 MN (25 tons), or 1.25 MN (12% tons) each. This principle can considerably reduce the length and weight of the support in comparison with a rigid pin-type structure; also, the yield load rating can be increased without affecting the lemniscate forces. The graph shows the tensile and compressive forces in a lemniscate linkage of a support with and without hydrostore. These forces react into both the roof beam and base members and, as can be seen from the support height to linkage load graph, a considerable reduction in these reactions is gained by the use of the FSW patented hydrostore system. Floor loading is considerably reduced under maximum µ conditions, and by allowing the roof bar to move with the strata, some degree of improvement to strata control is achieved in line with the assumptions in the paper. In practice, these movements have only been in the region of a few millimeters, which, in turn, reflects on the improvements to strata control by the addition of positive set valves.

Jan 1, 1987

By J. Choi

For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50?200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.

Feb 23, 2014

By S. B. Kim, J. Hong, K. Park, W. Kim, H. Kim, Y. Han, J. Choi

"For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50–200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.INTRODUCTION A great number of potential applications of lithium are being developed currently by the thermonuclear fusion power generation industry(1,2) as well as by the battery and fuel cell industry(3). Even though lithium is mainly consumed in the form of lithium metal and some lithium compounds, about 10% of total lithium production is consumed directly as mineral concentrates by the ceramic industry for the manufacture of special ceramics and mica based glass-ceramics(4). Granitic pegmatites normally contain feldspars, quartz, and mica in addition to lithium-bearing minerals such as spodumene (LiAl(SiO3)2), petalite (LiAlSi4O10), and lepidolite (KLi2Al(Al,Si)3O10(F,OH)2). The amount and grade of metallic minerals tend to gradually decrease and become lower, leading to the increase in the price of base metal or metallic compound(5). Accordingly, recent studies have been extensively devoted to developing the technique to improve the grade of metallic minerals from low grade metallic ores(6,7). Nevertheless, studies regarding the improvement of Li grade from lepidolite ores are very scarce. Lepidolite is a phyllosilicate mineral of the mica group and is often associated with other minerals such as calcite, muscovite, feldspar, and quartz, which need to be separated for lepidolite enrichment(8). Many studies have reported the flotation techniques for separating calcite, muscovite, feldspar, and/or quartz from various targeting minerals(9-11); however, there has been no attempt to investigate physico-chemical properties of lepidolite and its separation from such types of gangue minerals through flotation. Hence, in this study, for the first time, flotation has been carried out for the quaternary ammonium salts (stearyl trimethyl ammonium chloride (STAC, (CH3)3CH3(CH2)16NCl))-lepidolite system based on only the electrokinetic property of minerals that consist of lepidolite ores without adding any depressant to get an initial insight on its flotation behavior. The experimental variables that influence the lepidolite flotation such as amount of collectors, feed size and solution pH have been also examined."

Jan 1, 2015

By George D. Roberts

Dams are constructed to retard the flow of water or debris; therefore natural forces are constantly at work to remove such obstructions. To circumvent nature and avoid expensive trouble with a dam requires thoughtful far-sighted planning, careful construction control and vigilant periodic inspections to detect and repair deterioration at its inception. Although the factuality of the foregoing statements is apparent, all too many have failed to consider them in the past as will many in the future. "The economic, but safe construction of dams calls for the highest order of technical knowledge, practical experience and sound judgment." (1)

Jan 1, 1967

By D. Nebbia, R. Aliberti, F. Solesin

The launch of a Tunnel Boring Machine (TBM) is one of the most challenging activity parts of the construction of a tunnel. Challenges are coming from limited space available, learning curve, concurrence of other activities and in some cases from the geological conditions. Launching a TBM is an extraordinary and complicated operation requiring a great level of planning. The Earth Pressure Balance (EPB) TBM named “Chris” was successfully launched for the Northeast Boundary Tunnel, the largest component of the Clean Rivers Project in Washington, DC. Due to space and time constraints, the 8-meter diameter TBM was launched from a single 20-meter diameter shaft, with a 30-meter-long tail tunnel by means of umbilical connections. This paper presents the steps followed during the TBM assembly and launching to complete the excavation of the initial drive of the tunnel maintaining high level of efficiency and quality despite the space constraints. Specifically, it focuses on the methods and phases used to extract the excavated material (muck) from the TBM and from the tunnel, to supply consumables, precast rings and backfill grout. The paper presents results in terms of productivity, lesson learned and possible alternatives to be considered in similar conditions.

Jun 13, 2021

By Se-joon Kim, Jong-hwa Chun

"‘Gas hydrate’ is the common term for a solid material formed from the combination of various gases as ‘guest’ and water as ‘host’. A series of large-scale scientific drilling and coring programmes conducted since 2000 revealed that natural gas hydrate exists in a wide variety of accumulations in the sediments. The scaled-up onshore and offshore field production tests during the last decade show that gas production technology will be realized to make gas production from gas hydrates viable in the future, recognizing its potentials as one of the future sustainable energy resources.The total produced gas was approximately 470 m3 by the hot water circulation method over 6 days of operation in the permafrost-associated Mallik 2002 project in the Mackenzie Delta of Canada. In the Mallik 2007-2008 project, the gas was successfully produced stably by the depressurization method for 6 days, up to 13,000 m3 cumulatively. The depressurization method applied in the Mallik test was shown to be an effective way to produce gas from gas hydrates. The Alaska field trial to inject mixed gas of CO2 and N2 to exchange CH4 in 2012 was successfully done for the first time to produce maximum 1,270 m3 per day. A remarkable achievement was made by Japan when it completed its first offshore production test in the Eastern Nankai Trough, producing approximately 120,000 m3 of methane by the depressurization method over 6 days in March 2013. The technical challenges and scientific uncertainties obtained from Nankai Trough production test provide Korea with more considerations as to the aspects of well completion, reservoir formation and seafloor stability, sand control, flow assurance, environmental monitoring, and etc., due to the different geological setting and geomechanical properties of the Ulleung Basin in Korea."

Sep 1, 2014

By Christopher Mark

Area wide pillar failures, or “squeezes,” were once fairly common in underground coal mines. While rare today, they do occur. This paper describes seven case histories that were investigated by MSHA Technical Support. They occurred across the range of US coalfields, in both longwall and room-and-pillar mines, and involved development mining, pillar recovery, longwall panel extraction, and multiple seam interactions. Significant lessons from each are discussed.

Jun 25, 2024

By Simon D. Strauss

This paper discusses the ways in which the metals industries dealt with surplus capacity in the past, primarily the twenty years, 1950 - 1970. During this period, the bulk of metals production in the market-economy countries was controlled by private sector companies. Since then, public sector companies have played an increasingly important role in the metals industries of the market-economy countries. Of course, the change was not overnight. It occurred gradually over a period of many years. Indeed, by 1965, several developing nations had adopted policies of government control of metal operations previously in private hands. The metals industries are so many, so large and so diverse that the constraints of time make it impossible to deal with all segments. To illustrate the problems of surplus capacity in the metals industries during the period, this paper focusses primarily on three metals. One experienced rapid market expansion between 1950 and 1970; one had a growth more or less in line with the expansion of the world economy; and one lagged well behind the pace of industrial expansion. No one will be surprised if aluminum is identified as the metal with rapid growth; copper is identified as the metal that kept pace with the world economy; and tin is identified as the laggard. Individual computations of the rate of growth for these metals show some variations, but most estimates place the increase in aluminum consumption in the market economy countries between 1950 and 1970 at a compound annual rate of about 8%. The corresponding figure for copper is a compound rate of 4%. Tin consumption showed no growth. A widely accepted point of view is that sharply rising demand will force the price of a commodity to increase substantially in order to attract a necessary expansion of supply. The corollary to this is that stagnant demand will hold prices down, as there is no need to stimulate new supply and it may be necessary to force marginal producers out of the market. The experience with aluminum, copper and tin in the years 1950-1970 does not support this theory. In 1950, the average prices in the United States market as reported by the American Bureau of Metal Statistics were 17.74 a pound for aluminum, 21.24 a pound for copper, and 95.54 a pound for tin. The corresponding figures in 1970 were 28.74 a pound for aluminum, 57.74 a pound for copper and 174.24 a pound for tin. Aluminum, with the greatest market growth, rose by 60%, whereas tin rose 82% and copper by 172%. Clearly, other factors were a more important influence on price than was the trend of demand To revert now to the capacity issue, during the period under review aluminum demand was rising so sharply that that industry had no sustained problem with surplus capacity. Instead, if anything, capacity may at times have been a constraint on demand. The industry succeeded in attaining explosive market growth through imaginative research and promotion programs. Some of this growth was the result of substitution of aluminum for other commodities – steel, copper, wood and glass as examples. But much of the growth was the consequence of developing entirely new products through technological innovation. Prior to World War 11, the number of aluminum producers was extremely limited. Alcoa and Alcan in North American and Pechiney and Alusuisse in Europe were the dominant firms. The developing countries had virtually no production and in Japan and Germany production was only a small fraction of the North American output. During the War years the United States had financed the construction of many new facilities. After the war these plants were sold by the government to Reynolds and Kaiser in order to foster more competition in the market. Subsequently many other concerns became aluminum producers, both in the United States and elsewhere and competition for markets intensified.

Jan 1, 1989

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice (USPAP) and the Australian VALMIN Code to a complex mineral property appraisal assignment and previously to some modest assignments. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others and information and statements required from the client under the VALMIN Code. The exercises highlighted many positive features of both sets of standards. However, the author concluded that, without modification, VALMIN is incompatible with USPAP and the US regulatory environ¬ment. The author found that VALMIN violates US legal decisions regarding real property appraisal due to its requirement to include many items of business value. The US Securities and Exchange Commission's prohibition on reporting quantitative resource estimates proved to be a severe problem under VALMIN. Some VALMIN requirements could not be met due to the extent and quality of documents specified. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed. Management considerations for complex mineral-property appraisal assignments are also presented.

Jan 1, 2000

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice and the Australian VALMIN Code to a complex mineral property appraisal assignment. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others, and information and statements needed from the client. The exercise also highlighted many positive features of both documents. Some conflicts were found between the two documents. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed.

Jan 1, 2000

By David Mast, Irwan Halim, Brian Hagan, Kaveh Talebi, Jason Edberg, Amanda Foote

On June 14, 2023 Jay Dee Contractors’ Tunnel Boring Machine (TBM) “Phoenix” holed through and completed mining the second drive of the I-75 Segment 3 Storage and Drainage Tunnel. Completion of the tunnel came only after overcoming several challenges, including a groundwater intrusion event which deposited thousands of cubic yards of wet ground material into the tunnel. This paper will discuss the events which delayed completion of the tunnel by over nine months, the risk management and construction approaches assumed by the Design-Build team during bid, several challenges faced by Design-Build teams when building stormwater resilience tunnels using traditional Department of Transportation standards, and recommendations for improving risk allocation and proposal documents for future similar Design-Build tunnel projects.

Jun 23, 2024

By Todd Kilduff, Paul Wilkinson

Microtunneling is rarely a straight forward “business as usual” endeavor. More often than not, these projects take twists and turns that require on the fly, out of the box solutions to get the project completed. This paper is a case history of a 63-inch diameter, Permalok, microtunneling project, extending nearly 700 linear feet under a hill forming the left-hand abutment to an earth embankment tailings dam. The job had three major and unexpected challenges that required unorthodox solutions. Challenge #1— Face Configuration: The Santiago Formation, a cemented sand formation with widely varying strengths, presented a challenge to configuring the face with regards to the number and length of pics and cutters. Subtle differences in type and size of the tooling had a big impact on the performance of the machine. Challenge #2—Eccentric Loading: Issues at the launch shaft with the Permalok pipe adaptors caused eccentric loading on the casing pipe. This issue resulted in overstressing and breaking of several pipe joints that ultimately led to seizure of the tunnel. Challenge #3—Back-tunnel Excavation and MTBM Recovery: There were many detailed considerations into excavating a recovery tunnel to retrieve the MTBM, especially being under a high hazard earth embankment dam.

Jun 13, 2021