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By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions4/ issued by the Bureau of Mines, the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor and, if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1957

By Hazel B. Comstock

[This material survey on magnesium and magnesium compounds is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive, up-to-date information on mineral commodities and activities Magnesium, the world's lightest structural metal has become a most useful material in airborne and space vehicles, automotive equipment, machine tools, and consumer products. Use of magnesium on in basic refractories for iron and steel furnaces has expanded as the production of iron and steel has increased. Progress in converting steel furnaces to the use of oxygen has further increased the use of magnesium and magnesite brick.]

Jan 1, 1963

By Frederick A. Mumpton

Recent findings by medical workers on the association of certain zeolite minerals with the high incidence of pleural mesothelioma in two small Turkish villages have caused considerable excitement both in medical circles and in the synthetic and natural zeolite businesses. The 42 cases diagnosed between 1970 and 1977 in one community of 600 population in a region of altered volcanic tuff represent a virtual epidemic of this rare malignancy which normally strikes only about one person in a million. Cancer workers around the world expect that detailed environmental and epidemiological studies of the disease in these areas will shed considerable light on the cause of this particularly lethal form of lung cancer. Scientists and engineers developing uses for zeolite materials in industry and agriculture, however, are justly concerned that the preliminary results available on this situation will be used by environmental and regulatory organizations to label an entire group of miner- als as carcinogens on the basis of what is little more than circumstantial evidence. Although there is no question as to the large number of cases of mesothelioma in these areas of central Anatolia, the work to date has suffered from a lack of sound geological and mineralogical input. Ataman (1) stated that a "correlation" exists between mesothelioma and zeolites in this region; however, the geological data needed to document a direct relationship between the presence of zeolites in the volcanic tuffs surrounding the villages in question and the rate of malignant lung disease in the inhabitants have g been obtained, nor has evidence that suggests a cause-effect relationship between zeolites and cancer been reported. To provide fundamental information on the distribution of zeolite minerals in areas of central Turkey where high incidences of pleural mesothelioma have been reported and to evaluate from first-hand knowledge the published reports and news releases of medical workers engaged in assessing the problem, the following investigation was made.

Jan 1, 1979

By Iain B. Mackenzie

In 1997, a thin layer of Microtherm Microporous Insulation was used to replace fireclay brick behind the magnesia/chrome working lining in #5 refining furnace at BHP?s San Manuel AZ smelter. A 23°C reduction in shell temperature was obtained, together with a large increase in the working capacity of the vessel. There was no sign of metal penetration as a result of the increased insulation. Following these highly favorable results, BHP have introduced this product into all of their refining furnaces.

Jan 1, 1999

By Charles A. Weinstein

INTRODUCTION As a set of management practices, "Knowledge Management" (KM) has disappointed many of its early advocates. The core notion behind KM can be summed up in the oft- quoted adage, "If we only knew what we know." KM describes a set of tools, practices, and approaches for using data, information, and expertise-knowledge-resident in an organization to improve the performance of that organization. The idea was incubated, hatched, and grew among some the largest and most successful companies in the world. Some of these companies created "Chief Knowledge Officers." Many more collectively invested billions in a huge range of KM efforts, all designed to use their organizations' information and expertise to innovate, improve margins, sell, or accomplish any of a myriad of sound business goals. Some KM efforts were successful, and many were not.* Today, it is indisputably the case that KM as a named set of practices has fallen out of favor. Why, then, should KM be discussed at a conference on "Things that Actually Work" for plant operators? Because, in many instances, KM has actually worked. The practices that represent KM done right offer significant opportunities for plant operators to achieve real gains, especially in times of resource constraints and in the face of ever-increasing technical and commercial goals. The KM fad is all but over. The KM benefits continue to accrue to those who have applied the lessons learned from that fad, and implemented sound * Fair disclosure: I am not unbiased with respect to the potential impact of KM. Teltech has been a pioneer and leader in KM, both as a practitioner and as a leading consultant to other organizations.

Jan 1, 2004

By William Gleason

At 6,898 ft below surface, the historic No. 9 shaft at Resolution Copper near Superior, AZ is now the second deepest single lift mine shaft in the United States and connects to the deepest single lift mine shaft in the U.S., Resolution Copper’s No. 10 Shaft (6,989 feet). The shafts serve as ventilation and access for future underground development of what could one day become one of the most significant copper mines in the United States. It is from the base of No. 9 and No. 10 shafts that hundreds of employees of Resolution Copper, a joint venture of Rio Tinto and BHP, hope will soon be given the go ahead to begin driving lateral tunnels to reach a copper deposit that is estimated to contain 28 Mt or 40 billion pounds of copper. Copper was recently added to the U.S. Geological Survey’s (UGGS) critical minerals list, in large part because of increasing demand. A study by S&P Global Energy & Market Intelligence “Copper in the age of AI: Challenges of electrification” released on Jan. 8, 2025, “identifies a transformative trajectory for copper demand, projecting a surge from 28 Mt (31 million st) in 2025 to 42 Mt (46.3 million st) by 2040 – a 50 percent increase that underscores the metal's pivotal role in multiple technological and economic domains.” The surge in demand is driven in large part by the global energy transition, electrification of vehicles, growth of artificial intelligence and data centers, and most recently robotics. Meanwhile, geopolitical tensions have increased the focus on the need for the United States to secure more of its own mineral supply chain. S&P Global’s report is one of many warnings that while copper demand has accelerated rapidly, future supply is being held back. Resolution Copper stands out as one example of a known mineral deposit remaining locked in the United States’ complex and lengthy permitting slog.

Feb 1, 2026

By S. B. Kang

Magnesium has poor ductility at temperatures lower than 225°C and, as a result, Mg alloy sheets are produced via fairly complex thermomechanical processes consisting of numerous sequential steps of hot (warm) rolling with low reduction and intermediate recrystallization annealing operations. In context of the present study, a simple technology for the fabrication of magnesium sheets by hot (warm) rolling was applied to various magnesium alloys. The misch metal addition in those AZ alloys was done to evaluate the deformation behavior. Tensile tests were carried out for those AZ alloys after applying different heat treatments. The precipitation of ß phase (Mg17Al12 phase) induced different microstructures with various cooling method from solution treatment temperature, and also with various annealing treatment temperatures.

Jan 1, 2006

By Q. J. Browne, M. A. Miller

Silver Bell produces about 22,000T of fine copper annually from low-grade chalcocite and oxidized copper ore that is recovered by sulfuric acid leaching and SX-EW processing. The current mineable reserves are 146 million short tons averaging 0.39% Cu, at a 0.15% cutoff. Silver Bell utilizes two types of mining methods to develop the low-grade reserves: (1) a conventional blast, load and haul method for run-of-mine leach ore, and (2) rubblization of material on the margins of existing pits. Rubble leach ore is blasted, terraced with a bulldozer, and leached in place. Mining and/or rubble leaching is currently active in four separate pits. Laramide-age intrusive rocks host porphyry copper mineralization at Silver Bell. Quartz monzonite porphyry dikes and stocks, mafic-poor equigranular granite (alaskite), and sub-volcanic dacite porphyry are the predominant host rocks. Most of the ore currently mined comes from near-horizontal enrichment zones containing veinlets and disseminated grains of pyrite and chalcopyrite rimmed by chalcocite. Conversion from a milling operation to a leach only operation allowed for a much lower cutoff grade than was historically used at Silver Bell. Mine geologists were able to increase copper resources by drilling exploration targets that were previously interpreted to provide lower-grade mineralization below cutoff-grade for milling. Geologic parameters that effect the distribution of rubble and mineable leach ore include: ore grade and thickness, variable alteration styles in intrusive host rocks that affect fragmentation during blasting, acid consuming carbonate wallrocks (reactive skarn) which influence leach solution pH, solution flow paths and drainage, presence of leachable oxide mineralization in non-reactive skarn, and depth to hypogene mineralization which is currently uneconomic. Geologic parameters are used to predict rubble bench limits, vary blast hole spacing for consistent fragmentation, and correct errors in mineral zone classification based solely on blast hole assays. An expansion-drilling program has identified approximately 150 million tons of new leachable copper resources with an average grade of 0.35% Cu.

Jan 1, 2002

By Richard W. Hanford

The geotechnical construction industry generally considers soil mixing to be defined as an in situ ground improvement or treatment method by which a dry or wet reagent is introduced into the ground and is blended with the soil by mechanical or rotary mixing tools. This results in relatively homogenous mixtures whose engineering properties are improved and are greater than the soil properties before mixing. Reagents usually include cement, but may also include processed clay such as bentonite, when a reduction in hydraulic conductivity is desired, or other proprietary chemicals when chemical stabilization is the objective. Mixing may be either shallow or deep. Shallow Mixing is the term arbitrarily used for treatment of soils within the upper 30 feet; Deep Mixing denotes treatment below 30 feet to the depth limits of the equipment. Mixing equipment may consist of single or multiple-shaft tools having cutting and mixing blades of many different configurations. To avoid using proprietary nomenclature, reference to Shallow Mixing Methods (SMM) and Deep Mixing Methods (DMM) are the preferred terms. Although originally developed and patented in the United States in 1956, in situ construction using various soil mixing methods is more prevalent in Japan and the Scandinavian countries. Reintroduced into the United States from Japan in 1986 for ground improvement and liquefaction mitigation at Jackson Lake Dam, Wyoming, acceptance of soil mixing methods has been gradual but slow. Applications typically include:

Jan 1, 2001

By William S. Gardner

It is certainly an honor to have been invited to address the Deep Foundation's Annual Meeting on such a vast and weighty topic as "Present to Future Design Considerations of Deep Foundations." Acknowledging the enormity of this 30-minute assignment, I hope to at least scratch the surface of the topic deep enough to generate some thought and reflection. Design considerations, be they current or future, bring to mind a number of important subtopics which comprise the design process. As shown by Figure 1, a flow chart of this process describes, in general terms, the sequence of a deep foundation design.

Jan 1, 1991

By T. Oberthür

The Great Dyke of Zimbabwe constitutes the world?s second largest reserve of platinum group elements (PGE) after the Bushveld Complex in neighbouring South Africa. Within the Great Dyke, economic concentrations of PGE are restricted to sulphide disseminations of the Main Sulphide Zone (MSZ), which are currently mined at the Ngezi, Unki, and Mimosa mines. Near-surface oxidized MSZ ores have a large potential. Their total resources are in the range of ca. 160 ? 250 Mt; however, all previous attempts to extract the PGE from this ore type proved uneconomic due to low PGE recoveries (<< 50 per cent) achieved by conventional metallurgical methods. Within the ores of pristine, sulphide-bearing MSZ, the PGE are bimodally distributed. Platinum occurs mainly in the form of discrete platinum group mineral (PGM) grains (mainly bismuthotellurides, sulphides, and arsenides), whereas approximately 80 per cent of the Pd (and some Rh) is hosted in pentlandite. Within the oxidized MSZ ores, the PGE are polymodally distributed. Whereas arsenide- and sulphide-PGMs, making up ca. 25 per cent of the original Pt content of the ore, largely remain stable (relict PGMs), the remaining PGMs are disintegrated. The base metal sulphides are destroyed, partly releasing their base metal and PGE contents, and are replaced by iron oxides or hydroxides. Unspecified amounts of the PGE are redistributed and either form secondary PGMs, are found in chemically and mineralogically ill-defined (Pt/Pd)-oxides or hydroxides, or in iron-hydroxides, Mn?Co-hydroxides, and in secondary silicates. The problematic processing of oxidized MSZ ores is attributable to their complex nature and polymodal distribution of the PGE, prohibiting a significant upgrading of the ores by conventional metallurgical methods. Therefore, only bulk leaching methods are viable for ore treatment, and novel metallurgical methods have to be developed for the processing of these ores. Our ongoing work aims at locating the PGE in their mineralogical form in order to understand the mineralogical balance of the PGE in the ores and thereby facilitate the evaluation of metallurgical options for their recovery. A short overview on options and recent advances regarding the recovery of the PGE from oxidized ores is given.

Jan 1, 2012

By Steve Kral

The mining industry in northern Ontario is known mostly for its huge nickel deposits. Inco’s and Falconbridge’s nickel mines in the Sudbury Basin are the best known. And with nickel prices being what they are, interest in the region continues. And how. Inco and Falconbridge want to merge. Teck Cominco wants Inco, but without Falconbridge. Xstrata made a hostile bid for Falconbridge, which Falconbridge rejected. And, in June, Phelps Dodge trumped them all when it made an approximately US$40-billion friendly offer for Inco and Falconbridge in a two-part deal.

Jan 1, 2006

By F. Chiesa

Experimental results on thin and thick castings poured in aluminum A356 and magnesium AZ91E by the low pressure permanent mold process have been compared to the result of filling simulations for thin and thick castings. If the results of modeling is reliable when the liquid remains above the liquidus temperature, this is no longer the case when partial solidification occurs. The visco-elastic behavior of a partially solidified liquid is difficult to put into equation as it depends on the amount of shear it has been been subjected to. Attempts to predict misruns with a commercial software has been proven to be very difficult if not impossible; divergence of the numerical solution has been observed unless prohibitively long computing times are used. In order to overcome these difficulties from a practical standpoint, a simple method is proposed which consists in tracking the temperature of the advancing liquid metal front so as to make sure it will always be above so-called `Misrun Critical Temperature&apos; (MCT) determined experimentally for thin and thick aluminum A356 and magnesium AZ91E castings. If the liquid metal front falls below this temperature, a cold-shut or misrun is likely to happen at this location. The values of MCT for thin and thick in aluminum A356 and magnesium AZ91E were determined experimentally on misrun castings of extreme geometries (a thin 2.5 mm wall cover and a 6mm to 25 mm thick bell housing). MCT was found to be lower for magnesium AZ91E and for the thicker castings.

Jan 1, 2011

By L Abrahamsson

This paper describes results from a gender study for a new mine in Pajala, a small community in northern Sweden. Using a gender perspective, the study examines migration, education, local culture, the labour market, and work organisation as problems and opportunities in the regional context for the planned mine. The most obvious ‘gender issue’ for the Swedish mining industry is the very low percentage of employed women, which is even lower among mining workers. To recruit the best people, a company actively needs to attract both women and men; however, the mining companies find it difficult to recruit women as cultural, labour market and educational traditions as well as the mining companies’ own cultures often make it difficult for women to find work in the mining industry.The Torne&#229; river valley, the region surrounding Pajala, has a gender-segregated labour market and gender-stereotyped culture and few young women live in this traditional and oldish region. Many young people leave the region and this is especially true for women. Compared to the rest of Sweden, there is a low educational level, especially among the men. In the mining companies, as in many other male homosocial workplaces, the workplace culture has strong connections to a certain type of traditional masculinity (laddishness, a kind of ‘macho-style’) and for a long time this has excluded women. ‘Gender’, however, is not only a question of recruiting women to a male-dominated industry. An organisation that discriminates according to gender can become inflexible, hindering communication, learning, innovations and change processes. In mining companies, this can manifest itself in hesitant attitudes among the miners about safety as well as organisational and technological development.This study found that companies establishing a presence in this region should develop a strategy for how to deal with and manage the risks and opportunities in the surrounding society (the regional culture) as well as inside the company (the mining culture). This need to be strategic will also be required of future mining companies as they will face higher demands on safety, gender equality, and technology to become modern, efficient and lean organisations.

Nov 22, 2011

By A Buckley

Many policy issues facing the mining industry and affected communities are at a level of complexity that they can be called ‘wicked’ problems. The term ‘wicked’ in this context is used, not in the sense of iniquity, but rather as social and economic issues highly resistant to resolution. For the resource extraction sector and affected communities there are an array of challenges embedded in the industry’s production and profit paradigm, the remoteness of mineral reserves and affected communities’ expectations of economic benefit and a positive legacy. The mining industry as a whole is dominated by economic, political, legislative and market structures that influence and constrain interactions between mine operations and local communities. For communities, with particular reference to regional Western Australia, intractable problems include the uncertainty of, yet increasing dependence on, a mining economy. Questionable outcomes for local communities include the limited realisation of local employment and business development benefits, and low overall outcomes or low multiplier effects. ‘Wicked’ problems, according to the literature, are best addressed via collaboration. In the mid-west region of WA, with mining and infrastructure construction underway, alliances have formed between mining companies, the major port and rail infrastructure project (Oakajee&#160;Port&#160;and&#160;Rail) and regional and local governance stakeholders. The major impetus for these affiliations is to expedite planning and associated infrastructure development taking into account the lessons from other mineral-led regions. What has resulted is an array of innovative approaches to stubborn problems including planning well in advance of full-scale mining; regionally coordinated procurement; ‘mine ready’ local businesses; and strategic investments in social infrastructure; including community trust funds paid in advance of project delivery. This paper examines these innovative approaches/alliances and assesses their effectiveness in addressing long standing mining/community dilemmas.

Nov 22, 2011

By P Malkin, S Thomas, P M. Stone, D Kostyuk

In open pit mining, it is common that the bottleneck to productivity and profit lies in the truck-shovel mining operation, especially as strip ratios and mining intensity have increased with resource depletion and advances in mining equipment capabilities. This paper outlines a study of truck-shovel productivity using a new proprietary discrete event simulation platform for truck-shovel operations called MineDES. The study will specifically address the issue of whether truck queuing at shovels should be considered productive or not, and how mining engineers can determine the optimal truck fleet size for specific operational configurations.The MineDES simulation platform will be described and illustrated, highlighting the features that make it an appropriate tool for conducting the experiments at the heart of this study. The study encompasses a set of experiments, consisting of a number of simple truck-shovel operational scenarios for a benchmark open pit mining operation, which are simulated using MineDES. Each experiment is designed to highlight different factors, which are most important in calculating the ideal truck fleet size and for understanding the marginal productive impact of each additional truck added to the fleet. The scenarios will principally address the issues of how different types and levels of unscheduled equipment downtime and process variation, combined with the traffic delays/congestion arising in more intense mining operations, will affect productivity. The results of the experiments are interpreted using a simple fit-for-purpose cost and revenue model in order to highlight the indicative cost of over- or under-trucked configurations.The study has found that the optimal fleet size that maximises productivity and value will, in the presence of even small process variation, lead to non-zero trucks queuing at shovels on average. As process variations and unscheduled downtime events increase in the truck-shovel system, the required fleet size to optimise productivity and value increases. MineDES provides a convenient platform for quantifying this for real operations.CITATION:Kostyuk, D, Thomas, S, Malkin, P and Stone, P M, 2014. Is truck queuing productive?, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 267–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By Faruk Oksuz, Dave Schiemann, Matt Trotter, Mike Padilla, Miguel Sanchez, Carmen Scalise

"Chicago’s Tunnel and Reservoir Plan (TARP) is a nearly $4.0 billion and over 30 years long program and arguably the largest and longest combined sewer tunnel and reservoir system in the world. Recently, a massive tunnel construction is underway for connection of the McCook Reservoir to the existing TARP tunnel system. Once completed in two stages in 2017 and 2019, the reservoir will hold 38 billion-liters (10 billion-gallons) of combined sewer overflows (CSO) and flood waters from the city of Chicago and over 20 communities in Cook County, Illinois. McCook Main Tunnel will connect Chicago TARP’s Mainstream Tunnel to the McCook Reservoir. Connecting two 10-meter (33-ft) diameter tunnels at 92 meters (300 feet) underground has not been a simple task for the McCook Tunnel Project participants, the project owner U.S. Army Corps of Engineers (USACE), local sponsor Metropolitan Water Reclamation District (MWRD) of Greater Chicago, designer Black & Veatch, and the contractor, Kiewit Infrastructure Company (Kiewit). Yet alone excavating and lining massive size tunnels, the team is also challenged with live tunnel conditions in TARP Mainstream Tunnel that carries CSO and flood flows from city of Chicago which runs full during rain events and must remain in service at all times. The project is a noteworthy feat for engineering and construction with the upcoming installation of world’s largest underground wheel gates for flow control within the tunnel. In this paper, we describe one of its kind elements of this major tunnel system along with key design and construction considerations, specifically for the live tunnel connection which is a rare occurrence in the tunneling industry. INTRODUCTION The McCook Main Tunnel system consists of a 10 m (33 ft) finished diameter and 490 m (1,600 ft) long hard rock tunnel constructed from a 27.5 m (90 ft) diameter and 92 m (300 ft) deep main gate and tunnel construction access shaft. The gate shaft houses six high head 4.4 m by 9 m (14.5 ft by 29.5 ft) wheel gates to be installed in the bifurcated and steel lined section of the tunnel. The tunnel also includes portal and energy dissipation structures as it daylights into the reservoir."

Jan 1, 2016

By J. E. Hamak

This publication contains analyses and related source data for 151 natural gas samples from 19 States. Of the total samples, 138 were collected calendar year 1989. The remainder were collected earlier, but releases to were not received until 1989. All samples were obtained and analyzed as part of U.S. Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by mass spectrometer and chromatograph.

Jan 1, 1990

By Dennis R. Dolinar

Screen material in the form of welded wire mesh and geogrids are used in underground coal mines to prevent the fall of small pieces of rock from the roof between roof bolts. Further, if the screen is installed during the production cycle, roof fall injuries can be reduced significantly. Therefore, the National Institute for Occupational Safety and Health (NIOSH), because of the safety implications, conducted an evaluation of screen materials commonly used in U.S. coal mines to determine their support characteristics and identify the parameters that could affect their performance with respect to controlling the fall of rock from the roof surface. To evaluate the load and stiffness characteristics of the screen, a test frame was designed and installed in the Mine Roof Simulator (MRS) at the NIOSH Pittsburgh Research Laboratory (PRL). With this test set up, the screen is bolted at four corners of the frame and a center load is applied. The test set up allows for up to 20 in of screen deflection while the load and screen defection are continuously recorded. A series of tests were conducted to evaluate the effects of various parameters such as bolt tension, the type of load bearing surface and the size of bearing plates on welded screen performance. The most common screen material used in U. S. coal mines is an 8-gauge wire welded in a 4-by-4-in spacing or aperture. The peak screen load was normally limited by wire breakage. The conditions at the bearing plate influence the nature of the wire breakage. However, the screen stiffness was controlled by slippage at the bearing plates, and by weld and wire failure. The size of the bearing plate had a significant effect on the performance of the welded screen. Therefore, the design capacity of the 8-gauge screen is evaluated based on plate size. For a 6-by-6-in bearing plate the average peak load is 2,900 lb with a stiffness of 250 lb/in. For an 8-by-8-in bearing plate, the average peak load is 4,500 lb with a stiffness of 430 lb/in. These test results are based on a 4-by-4-ft bolt spacing. A geogrid mesh was also tested.

Jan 1, 2006

By William R. Yernberg

The combined 75th Annual Minnesota Section of SME meeting and 63rd Annual University of Minnesota Mining Symposium was held April 9 and 10, 2002, in Duluth, MN. This year’s theme was “Keys to the Future: Imagination, Innovation and Technology.” The meeting consisted of plenary and technical sessions and a special General Manager’s Session. The technical paper presentations included concurrent mining and mineral processing sessions. In the General Manager’s Session, representatives from the region’s taconite operations presented the current status, concerns and future plans for each of their operations.

Jan 1, 2002