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By George A. Roche

Since our firm was established by Mr. Price in 1937, we have followed an investment philosophy which is based on the belief that investment in growth stocks is the most assured way of achieving superior, long term investment accomplishment. There are many criteria that we use to select growth companies but the most important is a combination of superior management operating in an industry with above average growth potential. This growth stock approach is the cornerstone of our investment strategy for two of the three mutual funds sponsored by the Price organization and for our private clients. However, during the past 5 years we have seen inflation accelerate due to a variety of factors including the inability of our government to meet seemingly unlimited needs with limited revenue sources. While there might be temporary periods of price stability, we believe that inflation will still continue to be the investor's greatest problem in future years. Our conviction that inflation would increase combined with the acceleration of inflation in the late 1960s stimulated an intensive investment research effort, on our part, to identify those companies with strong natural resource bases -- who own or control large, secure, and low cost tangible assets. Over the longer term and in an environment of a depreciating dollar some of these firms should be able to develop and sell these assets at higher prices. While we still believe that investing in growth companies is a sound investment strategy to offset inflation, we also believe that certain natural resource companies will show well above average investment performance. In the newest Price mutual fund, The Rowe Price New Era Fund, we have, as a matter of policy, placed a large portion of the portfolio in natural resource companies.

Jan 1, 1972

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-theshelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m3/ min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.IntroductionThe Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the United States in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement (U.S. Mine Safety and Health Administration, MSHA, 2006). Section 13 of the MINER Act specifically directed the U.S. National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of refuge alternatives for underground coal mines. This mandate culminated in the 2009 adoption of changes to Title 30 of the Code of Federal Regulations (30 CFR) mining health and safety regulations, requiring underground coal mines to provide mine emergency refuge alternatives and associated components, to provide a life-sustaining environment for persons trapped underground. Such refuge alternatives can be either self-contained mobile units or built-inplace facilities. The regulatory changes also include provisions establishing requirements for MSHA approval of refuge alternatives and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the refuge alternatives. One specific criterion for maintaining a safe refuge alternative atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (0.18 psi), or at a pressure above mine atmospheric pressure, in the refuge alternative, as specified by the manufacturer when the breathable air is supplied by a fan or compressor (MSHA, 2008)."

Jan 3, 2018

By Joe Hachey, Jerry Dorn, Jeff Schutt, Derek Penrice

"Sound Transit’s East Link Project, a $3.7 billion (2015 $), 14-mile light rail extension, will connect downtown Seattle with the rapidly developing east side cities of Bellevue and Redmond. Among the most technically challenging aspects of the Project is the 2,435 foot long Downtown Bellevue Tunnel (DBT), which will be constructed through the central core of Bellevue underneath 110th Avenue NE using a combination of Sequential Excavation Methods (SEM) and cut and cover tunneling. The 1,980 foot long central SEM component of the DBT will be mined at shallow depth through challenging and complex geology, comprised of glacially overconsolidated soils, containing both regional and perched groundwater conditions and in close proximity to existing high rise buildings. The paper shares lessons learned from the planning decisions and risk based approach to the investigation, design and procurement processes which shaped the DBT configuration and enabled a successful transition to the project’s construction stage. INTRODUCTION The East Link Project is a voter-approved $3.7 billion (2015 $), 14-mile extension of the existing Sound Transit (ST) light rail transit (LRT) system from downtown Seattle, across Lake Washington via I-90, to the cities of Bellevue and Redmond on the east side of Lake Washington. With targeted completion in 2023, East Link will provide riders with an efficient and reliable connection between the largest population and employment centers on the east side and downtown Seattle. The project alignment is indicated in Figure 1 below.ST completed the Preliminary Engineering (PE) phase of the East Link project in late 2011. Subsequently the final design contract for the easternmost seven miles of the project was awarded to the H-J-H Team, a joint venture comprised of HNTB, Jacobs Engineering and Hatch Mott MacDonald in February 2012. H-J-H’s final design scope includes approximately 7 miles of double-track LRT between the east end of the I-90 East Channel Bridge and the Overlake Transit Center Station. While the project scope is extensive and diverse, the focus of this paper is the DBT. The DBT is located immediately north of the East Main Station, and travels approximately one half mile through downtown Bellevue under 110th Avenue NE between Main Street and NE 6th Street; terminating at the Downtown Bellevue Transit Center (BTC) Station. The location and extent of the DBT is indicated in Figure 2."

Jan 1, 2016

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

The paper describes the process of collecting detailed accounts of near-miss incidents and turning them into impactful visual stories using graphic simulation. The aim is to create high-quality training materials to reduce haul-truck-related accidents and fatalities in mining.

Sep 1, 2023

By G. Folmo

Allis Mineral Systems' GRATE-CAR agglomeration/induration/reduction process is currently being operated to process ilmenite at Tinfos Titan & Iron KS in Tyssedal, Norway. In this process, balled ilmenite concentrate is fed to a traveling grate where pellets are dried and preheated, using fully oxidized kiln exhaust gas. Hot preheated, semi-indurated pellets are fed directly to a ported kiln where reduction of the ilmenite's iron oxide fraction occurs in the presence of lump coal. The reduced pellet sand coal char are discharged from the kiln to an indirect rotary drum cooler. Cooled pellets and char are screened and magnetically separated prior to their further processing in a downstream smelting operation. The pellets are melted and the titanium dioxide and iron are separated. Operation commenced in late 1986.

Jan 1, 1992

By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By George O. Lower

The use of cyanides in the extraction of gold and silver is well known.1 Such extractions employ con¬centrations of cyanide in the range of 0.02-0.25 % sodium cyanide equivalent in leaching cycles of 24-48 hours and frequently longer. Copper minerals, even though minor components of precious metal ores, dissolve in these cyanide leaching solutions, consume cyanide, cause fouling of mill solutions, and thus interfere with the precipitation and recovery of gold and silver. 2,3,4 This paper presents a summary of laboratory investigations on the use of cyanide solutions as extractants for copper from various copper-bearing ore fractions. In view of the metal contents involved, it will be apparent that larger quantities of cyanide are required to extract copper than for the extraction of precious metals. In cyanide solutions of concentrations generally favorable to copper extraction, sulfide and oxide copper minerals were found to dissolve rapidly at room temperature and atmospheric pressure. For example, on products in the flotation size range, the major portions (e.g. 65-85%) of the extractable copper frequently dissolved in 2-10 minutes. At coarser grinds, e.g. 100% minus 28 mesh and 100% minus 10 mesh, 75-85% of the total copper was extracted in 30 minutes.

Jan 1, 1966

By VIVEK KASHYAP, Evody Tshijik Karumb, PATRICK TAYLOR

The partial reduction of zinc ferrite to zinc oxide and iron (II, III) oxide can enhance the leaching rate of zinc. Zinc ferrite has often been found as a major component of zinc residues and electric arc furnace dust. The Waelz process is an existing process for zinc ferrite processing, which requires a temperature of more than about 1200 °C to produce Waelz oxide containing ZnO. Since zinc residues have been deemed as a potential way for the extraction of zinc and other critical metals, it is important to analyze the reaction kinetics in the temperature range of interest. This manuscript discusses the chemical kinetics of zinc ferrite reduction by hydrogen gas. Several researchers studied the reduction of zinc ferrite with CO; however, unlike CO, the use of H2 gas as a reductant allows partial reduction of zinc ferrite even at low-temperature range (400–600 °C). Thermogravimetric analyses (TGA) experiments were performed in the temperature range of 300–700 °C with 10% and 30% H2, and the data obtained was analyzed using the isoconversional method of kinetic analyses. The standard models used for isoconversional kinetic analysis were chosen from literature and experimental data were fitted to determine the controlling mechanism and calculation of kinetic parameters of reduction of zinc ferrite. The rate of reaction was found to be increasing with an increase in temperature and partial pressure of H2 gas. The reaction could be divided into three stages, where reaction interface contraction was found to be the controlling mechanism at the initial stage of reaction. As the reaction proceeds, product layer thickness increases, and thus, diffusion was found to be the controlling mechanism. Roasting products obtained from TGA experiments were also characterized using a scanning electron microscope (SEM) to verify critical morphological details.

Jul 26, 2022

By William Hodder, Ehsan Alavi, Muhib Hussain

Disc Cutter Wear is influenced by several geological and technical factors and excessive wear can have a major impact on the excavation efficiency of Tunnel Boring Machines (TBM). Disc cutter replacement events cause a disruption to the construction schedule and costs, and should be minimized throughout the project to the extent possible. A well-executed cutterhead inspection and maintenance plan can help mitigate abrupt cutterhead interventions and reduce its effect on project schedule and cost. This paper examines cutterhead inspection and disc cutter replacement events as well as subsequent wear data recorded in the first 7km of the 10.3 km long, 6.3 m diameter Coxwell Sanitary Bypass Tunnel (CBT) project in Toronto, Ontario. The CBT alignment is mainly through Georgian Bay Formation shale.

Dec 1, 2022

By Jamal Rostami, Tom Iseley, Saleh Behbahani

Tunnels and underground infrastructures assets, like all assets, deteriorate with time. At some point, they reach the end of their useful life. Therefore, frequent inspections, higher levels of maintenance, and rehabilitation are needed to address loss of life and safety concerns. The repair cost of tunnels will increase if maintenance of tunnels is not satisfactory and timely. Historically, tunnel inspections have primarily relied on visual and manual procedures. Due to their time-consuming nature and susceptibility to human error, there is a demand for alternative automated techniques that can enhance efficiency and reliability in tunnel inspection. By utilizing a tunnel scanning system, such as laser scanner and thermography, or photogrammetry system, tunnel inspection cost, time, and personnel can be reduced. The goal of this study is to utilize deep convolutional neural networks (CNNs) for automated identification of defects in tunnel lining inspection. This paper presents a framework to classify two types of defects in tunnel lining (water leakages and cracks) using CNNs. The CNNs were trained and tested using 4,608 images. The Precision, Recall, and F1 Score were each 99.6%, confirming the viability of this approach in the automated defect identification in tunnel lining.

Jun 23, 2024

By Milan Yekich, Emanuele Cauda, Justin Patts, Cody Wolfe

A worker’s personal exposure to respirable dust in occupational environments has traditionally been monitored using established methodologies which entail the collection of an 8-hour representative sample that is sent away for laboratory analysis. While these methods are very accurate, they only provide information on the average exposure during a specific time period, generally a worker’s shift. The availability of relatively inexpensive aerosol sensors can allow researchers and practitioners to generate real-time data with unprecedented spatial and temporal granularity. Low-cost dust monitors (LCDM) were developed and marketed for air pollution monitoring and are mostly being used to help communities understand their local and even hyper-local air quality. Most of these integrated sensing packages cost less than $300 per unit, in contrast to wearable or area dust monitors specifically built for mining applications which have been around for decades but still average around $5,000 each. At the National Institute for Occupational Safety and Health (NIOSH), we are leveraging the power of high-volume data collection from networks of LCDM to establish baseline respirable hazard levels and to monitor for changes on a seasonal basis as well as following any application of control technologies. We have seen the effective use and advantages of monitoring live data before, during, and after events like shift changes, operational changes, ventilation upgrades, adverse weather events, and machine maintenance. However, many factors have prevented a systematic adoption of LCDMs for exposure monitoring: concern for their analytical performance, the complexity of use, and lack of understanding of their value are some factors. This contribution outlines a one-year case study at a mine in Wisconsin USA, covering the installation, maintenance, data visualizations, and collaboration between NIOSH researchers and the industrial hygiene professionals at the mine.

Feb 1, 2024

By N. Dashbold, E. Rudnik

"Waste electric and electronic equipment currently comprises the fastest-growing waste stream in the world, but at the same time it is seen as an important source of metals for the recycling industry. E-waste is usually treated pyrometallurgically, with hydrometallurgical methods used to a lesser extent. This paper reports the results of research on the selective recovery of copper from smelted low-value electronic waste. Pyrometallurgical pretreatment of the scrap allowed the removal of plastics and the increase of metal content in the material. The obtained alloy of copper, zinc, tin and silver was a multiphase solid consisting of two brass phases and inclusions rich in iron, lead and silver. Copper alloy was further anodically dissolved in ammoniacal chloride solution. It resulted in high degradation of the material and accumulation of the metals mainly in the slime. The slime was then leached in acid or ammoniacal chloride and sulfate solutions followed by selective copper electrowinning. Hydrochloric acid was the most efficient solvent for the slime, but ammoniacal solutions were more selective for copper. Copper could be leached with 96 to 100 percent and 87 percent efficiency from the slime by the chloride and sulfate solutions, respectively. Copper with 90 to 99 percent purity at current efficiency of 42 to 76 percent was obtained from the acid solutions, while copper with 98 to 99 percent purity at current efficiency of 60 to 86 percent was deposited from the ammoniacal baths. IntroductionObsolete electrical and electronic equipment makes up the fastest-growing waste stream in the world (Baldé et al., 2015), due not only to the introduction of wider ranges of new types and models of a variety of electronic products but also to the shortening of their life-spans, sometimes referred to as planned obsolescence by producers (Keeble, 2013). About 42 million tons of electronic waste, or e-waste, are estimated to have been generated globally in 2014 (Baldé et al., 2015), and it is expected that in the European Union alone the waste electrical and electronic equipment (WEEE) stream will reach more than 12 million tons by 2020 (European Commission, 2015). Accurate evaluation of e-waste generation (Wang et al., 2013) and its global transport (Breivik et al., 2014) is difficult, mainly due to a lack of high-quality data related to its market and socio-economic dynamics.Many countries introduced legislation to control e-waste flow, collection and recycling. For example, Directive 2012/19/EU on waste electrical and electronic equipment (European Parliament and the Council of the European Union, 2012) obliges all E.U. members from 2016 to maintain a minimum collection rate of 45 percent of the total weight of WEEE collected. From 2019, the minimum collection rate to be achieved annually shall be 65 percent of the average weight of electronics placed on the domestic market in the three preceding years, or alternatively 85 percent of WEEE generated in the territory of the particular member."

Jan 1, 2017

By Ronald J. Roman

As in every business venture, the primary objective of a mining operation is to make money for those who supply the venture capital. Therefore, all decisions concerning the operation of the mining operation should be made in light of the resulting effect on profit. The ultimate control is on profit, but the process is controlled, for example, by aiming for a recovery or concentrate grade knowing its effect on profit. The normal procedure used to determi.ne the profitability of a venture is to "present worth" all costs and incomes back to some arbitrary year zero. Every company has formed a management decision as to what it will require as a minimum return before it will undertake an investment. Once the economic analysis is completed, investment will be made only if the venture shows a positive present worth. If two alternatives are available, the alternative with the larger positive present worth is the one chosen. The same principles can be applied to the selection of a production schedule.

Jan 1, 1971

By Michael Cruickshank

All life on Earth relies on the ocean and yet the ocean is 95 percent unexplored, unknown and unseen by human eyes,? said Paula Keener, director of education programs for National Oceanic and Atmospheric Administration?s (NOAA) Office of Ocean Exploration and Research. ?To better understand, manage and protect the ocean and its resources, NOAA believes it is critical to use the best technology to explore, discover, inform, educate and motivate? (MTS, newsletter, January 2011). In the last few decades, our understanding of the global mineral resource base has been drastically changed by some surprising new developments. The potential for commercial minerals per unit area in the oceans and seabed appears to be similar to that of the terrestrial lands. Thus, almost three-fourths of the global mineral resources are in, or under, the sea and are virtually undeveloped. The area of the Pacific seabeds alone is greater than the total area of the global lands. Half of the global seabed minerals are now controlled by nation states within their Exclusive Economic Zones (EEZ). The other half is controlled by the United Nations (UN) through the International Seabed Authority (ISA) within the ?areas beyond national jurisdiction? known as The Area. Thus, the Law of the Sea, ratified in 1994, has resulted in the largest transfer of control of natural resources in the history of mankind. This paper was prepared by the Society for Mining, Metallurgy and Exploration (SME) Committee on the Offshore Technology Conference for the SME Board of Directors and other interested parties. As the premier professional society for the mining and mineral community in the United States, with a history dating back to the 19th century, SME?s mission is to encourage and support young men and women engineers in the minerals industry, provide the services they need, improve the image of the industry, strengthen the networking among global industry professionals and engage in proactive collaboration among industry, government, academia and nongovernmental organizations (NGOs). The accomplishment of this mission can be strongly advanced by highlighting what is probably now the most significant development in the history of the modern minerals industry - the exploration of the marine environment and the understanding of the potential for the development of the minerals therein.

Jan 1, 2011

By I. Chatterjee

The application of microwaves has a demonstrated potential for the ultimate removal of water from fine coal. The principle of microwave drying of fine coal is based on the selective absorption of microwaves by water. Coal is a poor absorber of microwaves. As a result, water can be removed from fine coal by selectively heating water molecules. One of the difficult problems drilling microwave heating is the exact determination of temperature in the core of the materials. The electromagnetic energy absorption in coal/water mixtures during microwave drying is controlled by several factors including the dielectric properties of the constituents. In this paper the dielectric properties of various ranks of coal are presented as a function of frequency and moisture content. The measured dielectric data are incorporated into electromagnetic and thermal models of coal which predict the energy absorption and temperature distribution during microwave heating.

Jan 1, 1990

By Tianzu Yang, Weifeng Liu, Lin Chen, BOYI XIE, DUCHAO ZHANG, HUI XIAO

In this study, the oxygen-rich bath smelting process of copper dross was simulated using Factsage software. It was found that the two-step simulation results agreed better with the industrial data, especially in the speiss. Bismuth (Bi), lead (Pb), antimony (Sb), arsenic (As) and copper (Cu) contents in the speiss by two-step simulation differed from the industrial data by 0.6, 0.8, 2.6, 7.2 and 8.6 weight percent, respectively. The two-step simulation results indicate that the speiss partitioning of Sb, As and Cu increased from 60.1, 32.3 and 27.5 percent to 81.6, 67.8 and 47.2 percent, respectively, with the smelting temperature increasing from 1,050 to 1,250 °C, while the metal partitioning of Sb and Cu increased from 0 and 2.7 percent to 15.2 and 13.3 percent, respectively, with the separation temperature increasing from 400 to 700 °C.

On Feb. 16, 2012, the Polish coal mining company Lubelski Wegiel Bogdanka S.A. set the world record for daily production from a plow-equipped longwall, with an output of 24.4 kt (26,900 st) of coal from a single face. The company commissioned the first Cat longwall system at its Bogdanka Mine, near Lublin in eastern Poland, in March 2010 and within six months had raised the bar to nearly 17 kt/d (18,700 stpd) of cut coal. Since then, Bogdanka has continued to increase its daily output with a plow face that began mining in the new 7/VII/385 panel last October, taking the world record to new levels. In addition to the record output achievement, the plow face advanced more than 27 m (89 ft) at a 1.63-m- (5.3-ft-) cutting height. ?We thought this achievement would be impossible for any shearer in seam heights as low as this,? said Zbigniew Stopa, vice president of Bogdanka.

Jan 1, 2012

By James M. Barker

Industrial minerals are critical to most aspects of modern society. They are pervasive in both industry and in everyone's lives (McVey, 1989; Barsotti, 1993). They are also the dominant class of minerals produced in the United States but this fact is little known outside the industry. For example, in 1993 (U.S. Bureau of Mines, 1995, table 1) industrial mineral dollar value was double that of metals ($20.86 billion vs. $10.88 billion) and employment levels were nearly so (74,000 vs. 40,000). A further difference is that transportation tends to dominate production costs (FOB end user) whereas they are much less significant in other mining ventures or other industries. Finally, metal mines are more concentrated west of the Mississippi; industrial mineral operations are more prevalent to the east (U.S. Bureau of Mines, 1995, p. 16-17). The significance of transport cost is discussed in Part 2, which is essentially Barker and Austin, 1995. Part 1 will update and expand portions of Barker and Austin (1995) and provide a more detailed discussion of import/export relationships using a China/United States reference point because of China's dramatic influence on some industrial mineral markets since the mid-1980s (barite, etc.).

Jan 1, 1996

By J. Marsden

Lift height, overall heap height and climate all play an important role in determining precious metals leaching rates, recoveries, operating costs and capital cost requirements for heap leaching operations. The effects of these factors are not easy to predict from testwork, and this can result in unexpected delays in metal production, lower recoveries than expected and higher capital and operating costs than necessary. This paper investigates the economic impact of lift height, overall heap height and climate on heap leaching and provides criteria to assist in the design and operation of leaching facilities. Descriptions of three heap leach operations in the western USA are provided to support the discussions and conclusions.

Jan 1, 1995