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By Henry N. McCarl

The New England States form the most northeastern portion of the continental United States and include Connecticut, Rhode island, Massachusetts, Vermont, New Hampshire, and Maine. These states have an aggregate population of over 10.5 million people, and an average annual population rate increase of about 1.3%. A great deal of new construction is required each year to meet the increasing demand for new homes, roads, offices, factories, and warehouses. Yet, prices of construction materials such as blocks and concrete are generally higher in New England than in other well populated areas of the United States. This is an indication of local demand being somewhat greater than supply, an atmosphere conducive to new developments in the production of construction materials. One such field of development is the rapidly growing Lightweight Aggregate Industry. Recent construction in Boston has used a great deal of lightweight aggregate. New structures using lightweight aggregate in lightweight concrete include the following: M.I.T.'s 20-story Earth Science Center and 17-story Married Students Housing Project Prudential Life Insurance Center, West End Redevelopment Project at Charles River Park, Hotel Americana, and the British-owned 33-story office building at 50 Pearl Street.

Jan 1, 1964

By Emmet K. Oslen

Kaiser Steel Corporation, the pioneer steelmaker on the Pacific Coast, was founded by the late Henry J. Kaiser. In 1944 the Company purchased from the Southern Pacific Railroad an iron ore property 200 miles east of Los Angeles known as Eagle Mountain. Today the domestic operation of Kaiser Steel Corporation consists of the iron mine at Eagle Mountain; two coal mines, one each in Utah and New Mexico; an integrated steelmaking complex at Fontana, California; and several steel fabrication and erection facilities along the west coast. Kaiser Steel also has interest in Hamersley Iron, Ltd., Australia, and Kaiser Resources, Ltd., British Columbia. Eagle Mountain Mine is located about 80 miles east of Palm Springs and adjacent to the southeast corner of Joshua Tree National Monument. The area is one of the most arid in the world averaging only two inches of rain annually. Geologically, the mine is at the western edge of the Basin and Range Province which covers about one-half million square miles of the western United States. The Province is typified by north to northwesterly trending fault block mountain ranges separated by sediment filled valleys, Production has totaled over 82 million tons of finished products since the first shipment in June, 1947. Over 500 million tons of material have been mined from the deposit to date. Eagle Mountain Mine is noted for the pioneering use of the largest and most up to date equipment to mine and process its ore. In 1961 Eagle Mountain received the first fleet of 100-ton haulage trucks in the mining industry. There were thirteen semi-trailer units in the fleet. The first 12 to 17-yard size shovel in the mining industry was placed in operation at Eagle Mountain during 1962. Rotary drilling was introduced at Eagle Mountain in 1954 to replace churn drilling. Eagle Mountain was the first major mine to use metallized slurry when three aluminum slurries were introduced for primary blasting in 1962.

Jan 1, 1972

By Henry R. Linden

The demand for natural gas continues to increase at higher than anticipated rates, partly because of its widening price advantage over most other fossil fuels when the cost of air pollution control is included. However, there are clear indications that natural gas supply from the contiguous 48 states and continental shelves will not indefinitely keep up with this rapid growth in demand. Projections are presented which define the extent of potential deficiencies from the 1970's to the year 2000. Among the sources of supplemental gas - imported pipeline natural gas from Canada and Mexico, tanker import of liquefied natural gas, and synthetic pipeline gas from coal and oil shale - by far the most abundant at potentially competitive costs is pipeline gas from coal. The state of development and relative economics of the various coal gasification processes are reviewed. It is shown that synthetic pipeline gas could become a very substantial market for bituminous coal and lignite at current minemouth prices - 60-70 million' tons of coal for each trillion cubic feet of synthetic pipeline gas produced. This corresponds to only slightly more than the current annual increase is gas demand.

Jan 1, 1969

By J. Hollow, D. Walsh

The Fort Knox Mine is located in Alaska’s interior, where the average ambient air temperatures range from -24oC in January to 16oC in July. The mill processes a free milling gold ore utilizing both a gravity recovery circuit and a conventional cyanide leach/carbon-in-pulp circuits. Mathematical models have been developed to accurately predict the impact of leach circuit slurry temperature on gold leach, carbon adsorption and cyanide destruction kinetics. Additionally, an energy balance approach has been used to model the seasonal variations in slurry temperatures throughout the Fort Knox mill. The energy balance model, combined with the kinetics models previously developed to predict plant performance, was used to justify a tailing thickener installation at the Fort Knox Mine. This paper describes the development of the energy balance model and its prediction of plant performance assuming a tailings wash thickener to reduce heat loss from the mill. Also presented is an analysis of the post project plant performance that validates the model and shows the mine produced an additional 596 kg (19,155 ounces) of gold, while reducing mill reagent costs by $6,302,000 during the first 38 months of operation.

Jan 1, 2007

By G. E. Vaninetti

During its modem era, the southern Powder River Basin (PRB) in Wyoming has grown from meager origins in the early 1970s to become one of the most important coal-producing regions in the United States. In 1993, production and sales of southern Powder River Basin coal exceeded 190 Mt (209 million st), or about 20% of the US coal industry. Despite the remote location of the PRB relative to its potential markets, most coal industry observers anticipate continued strong growth to meet utility compliance plans for Phases I and II of the Clean Air Act Amendments (CAAA). This article is an overview of supply and demand issues concerning the marketing of southern PRB coal. It reviews the events leading up to the recent run on spot coal and offers a forecast of demand and prices.

Jan 1, 1994

By Mark Van Dyke, Ted Klemetti, Jake Beale, Zoheir Khademian, Joe Wickline

In 2016, a 3.7-ML magnitude event caused by mining activity occurred at a longwall mine in southwestern Virginia which was recorded by the United States Geological Survey (USGS) and felt by local residents. The event was the largest of its kind since a global mine design change by the operator was instituted in 2008 following three large events in 2005, 2006 and 2007 (3.4, 4.3, and 3.4, respectively). Two of the three pre-2008 events (2005 and 2007) damaged ventilation controls in the mine which fueled a mine fire. In 2016 the mine’s management requested researchers from the National Institute for Occupational Safety and Health (NIOSH) to access geological data and determine what parameters could possibly lead to events of a magnitude of 1.0 ML or greater. Evaluation of 2,152 geological data points and modeling revealed three major geological factors in common with the majority

By L Usoni

Collectors commonly used in flotation to date fall into two main classes: ionic and nonionic. The use of neutral or oily collectors is generally limited to the flotation of nonpolar minerals onto which they are adsorbed by forces of a physical or 'Van der Waals' type, while ionizable chemical collectors are utilized for all other types of minerals, adsorption in this case involving bonds essentially of a chemical nature. Though chemical adsorption is more selective than physical adsorption, even heteropolar collectors are active towards certain classes of minerals (sulphides for example) rather than towards one individual mineral. Thus, in order to float a given mineral from a mixture of minerals belonging to the same class, modifiers have to be used to render the action of the collector more specific. However, there are often considerable difficulties involved in this procedure and the desired results are not always attained, especially in the case of minerals of complex composition whose surface properties are not sufficiently well known. Hence the importance of seeking out collectors capable of linking selectively with given minerals. Selective linkage is possible if the collector structure incorporates active groups having specific affinity for certain cations characteristic of the mineral surface. The decision to investigate the possibility of utilizing chelate--forming reagents for flotation was based on the premise that phenomena which occur in solution and involve chemical reactions in the strict sense of the meaning and those which occur on the surface are closely correlated (1)

Jan 1, 1971

By A. E. Hall

INTRODUCTION Underground gold mining operations are found in South Africa, U.S.S.R., Canada, the United States, Zimbabwe, Ghana , Brazil. Australia, China and many other countries. The methods used for extraction differ from highly mechanized trackless mining in the developed countries to the labour intensive systems of the third world nations. The climatic conditions in which mines are situated vary from equatorial to arctic. The rock temperatures and the depth of workings also vary significantly from shallow to extreme depth. The Western Deep Levels mine in South Africa is the deepest and exceeds 4.000 metres in depth with strata temperatures above 55°C. These major differences between mining fields result in significantly different ventilation problems in underground gold mines. The ore types also vary and some deposits have high silica contents while other mines extract sulphide ores. Methane may also be encountered in underground gold mines and can have a large influence on the ventilation practice. Several topics are currently of concern to operating mines and are reviewed here:- a) Air circulation and fans b) Mine cooling c) Permafrost operations d) Mine heating e) Control of diesel exhaust f) Gases, fires and explosions

Jan 1, 1988

By G. Almgren

With the exception of sublevel caving, the most common method of underground mining in Sweden is the "cut-and-fill" method. It is normally used for mining non-ferrous metals , and' is used extensively in the complex sulfide ore mines of the Boliden Company in north and central Sweden as well as the mines of the STORA and Vieille Montagne Companies in central Sweden. All in all, the cut-and-fill method is used in 13 of Sweden's 45 mines. As the mines are relatively small, the volume of ore mined by this method represents only about 5 % of the total ore production in Sweden. The commercial value, however, is much large than this percentage would imply. The production volumes and grades of some typical mines are shown in Table I. As seen, when rated internationally, the grades are comparatively low. The prices are set according to ?international metal prices? as dictated by the London stock exchange, and in lieu of governmental support, rational management methods are critical in order to achieve satisfactory profit.

Jan 1, 1975

By Marcos de Paiva Bueno, Leonardo Ribeiro Lara, Rajiv Chandramohan, Thiago de Almeida, Greg Lane

This paper explores the impact of the significant difference between the number of geochemical assays conducted for grade estimation and the number of comminution tests performed for throughput and performance forecasting. Both grade and throughput are key factors in determining the project. We analysed 154 feasibility study reports to assess the impact of sample frequency for comminution test work on project revenue. This disparity in size between assay and comminution data arises because geological and resource-grade risks cannot be managed without extensive geochemical testing, whereas comminution risks are traditionally mitigated through design methods and the use of contingencies. This approach is partly due to the relatively high cost and large sample requirements associated with traditional comminution tests. Our analysis demonstrates that insufficient comminution sampling and testing leads to uncertainties in throughput forecasts, creating significant financial risks. Data from the feasibility studies show that a 1% change in mill throughput can result in up to a 5% variation in Net Present Value (NPV), underscoring the sensitivity of project economics to operational performance. Building on previous work, we reference studies that reveal how low frequency of comminution testing can increase uncertainty in mill throughput forecasts and increase financial risks. We propose an approach that optimises the number of comminution samples tested to enhance forecast accuracy and reduce NPV variance. By adopting this approach, mining projects can improve financial reliability and mitigate risks associated with underperformance in SAG and AG mill-based operations.

Feb 1, 2025

By Carrie Smith

The 2025 Women in Mining USA National Conference, held April 15-18 at the Grand Hyatt Riverwalk in San Antonio, TX, brought together hundreds of professionals for a fourday event focused on empowering women and creating space for all individuals in the industry. Under the theme “Empowering the Future of Mining,” the conference served as a dynamic platform for professional development, knowledge-sharing and cross-sector collaboration. Organized by Women in Mining USA (WIM USA), whose mission is to foster equity, sustainability and leadership in mining, the event featured an extensive agenda including workshops, keynote speeches, panel discussions and networking opportunities. Attendees ranged from industry veterans to emerging professionals and students, united by a shared commitment to progress within one of the world’s most essential and traditionally maledominated sectors.

Jun 1, 2025

By Ross W. Whipple

Applying geophysical techniques in potential geothermal areas has received: little attention in the United States, though it is widely used and accepted in New Zealand and Italy. In those countries it has been demonstrated that geophysical surveys can be useful in locating new geothermal areas and in directing test drilling programs. Geophysical studies in a thermal region can provide structural information and, if conditions are right directly; locate subsurface hot waters. They can give indications of sub-alluvial rock types and of the thickness of alluvial cover. In certain cases they can be used to estimate the power potential of a hydrothermal system.

Jan 1, 1963

By Alice Blount, F. Patrick Carr

The quantitative evaluation,of quartz and other minerals in acid-insoluble residues from carbonate rocks and other industrial mineral products derived from sedimentary and low-grade metamorphic rocks is difficult. Commonly there are a dozen or more minerals present, and the suites vary from sample to sample. Because of these factors, either the absorption coefficient must be determined on a sample to sample basis or an internal standard must be used. Internal standards in general use are unsatisfactory. For example, [A1203] is often present in product samples because of ceramic grinding elements used in their production; CaF and LiF have peaks which overlap or nearly overlap mineral peaks in the samples. A careful evaluation has shown that magnesium aluminate (synthetic spinel) works particularly well as an internal standard for these types of samples. Not only does it have few, strong diffraction peaks which do not overlap, the peaks are in the same 28 region as the minerals, usually quartz and silicates, for which quantification is desired. Spinel also consists of equidimensional particles without prominent cleavages; this promotes a random orientation of the minerals in X-ray diffraction mounts. In addition, spinel can be used to correct for loss of diffracted-beam intensity due to thin sample preparations which are often unavoidable.

Jan 1, 1991

By D. Richter

The Pyrometallurgical refining stage of ferronickel manufacturing produces a slag rich in iron and nickel, which is usually further processed for metal recovery. The recovered material is returned to the refining or smelting stages, depending on the amount of impurities. A series of tests was carried out on the Mineração Morro Azul refining slags, aiming at the recovery of the metallic particles through physical processing. Minor changes in the process showed improved results. This paper compares the textures of these slags after being cooled at ambient temperature and granulated under water at high pressure and flow. It concludes that the cooling process is intimately connected to the work index of such slags, thus resulting in direct impact in operating costs.

Jan 1, 2011

By Roberto J. Guardia, Tim Shell, Robert A. Robinson, Steve Rodolf

Our aging infrastructure includes numerous tunnels that provide easy access through topographic and societal obstacles. These tunnels are renewable resources that require periodic maintenance and rehabilitation to extend their useful lifespan to hundreds or even thousands of years. However, as with any structural rehabilitation project, tunnel liner rehabilitation requires an inordinate amount of evaluation and care due often poorly documented original construction and subsequent repair construction methods and materials. This paper documents the investigation, planning, design, and construction efforts of the rehabilitation of a 74-year old, 216-meter (713 foot) long two-lane highway tunnel in moderately fractured to highly sheared basalt on the Oregon coast. The tunnel consists of four sections lined originally with timber and subsequently overlaid with concrete, and three unlined sections.

Jan 1, 2005

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2015 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL) (Charlottesville, VA) database and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry, and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: budgetary statistics expressed in U.S. dollars provided by SNL; regional and site-specific exploration activities that took place in 2015 as compiled by the USGS; and regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2015 for 24 nonfuel mineral commodities and metal alloys and are based on company surveys. Surveys focused on precious metals (gold, platinum-group metals and silver), base metals, (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (diamond, graphite, heavy-mineral sands, lithium, niobium, rareearth elements (REE), tantalum, tungsten and uranium).USGS data compilations and analyses are based on information provided by USGS mineral commodity and country specialists, as well as industry contacts and published trade journals. The USGS data summarize exploration site data collected for more than 80 minerals and materials, with a focus on base metals, diamond and precious metals. The USGS analyzed available information to assess the level of exploration activity in 2015 and to report trends in mineral exploration activity for the period 2005 through 2015. These analyses identify where mineral exploration is occurring by commodity and region and the intensity of activity that is taking place in each region for selected mineral commodities, and determines those factors that most affect changes in exploration activity."

May 1, 2016

By W. L. Price

Recent publication of United States Bureau of Mines figures showed that the sand and gravel (3) industry is the largest single mining industry in the United States in term of yearly tonnage produced. The yearly production of over 500,000,000 tons per year now exceed bituminous coal production. This disclosure caught unawares many observers who have not been following closely the rapid-growth of this phase of mining. Along with this steady growth in production, the sand and gravel industry has gone through an accelerated and varied program of beneficiation in a period of the last ten years.

Jan 1, 1958

By Rick Bearce, Minsu Cha, Mike Mooney, Yuanli Wu, Lisa Mori

"Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. Chamber pressures can reach 3-5 bar yet the vast majority of testing is performed under atmospheric conditions. This paper illustrates how pressure influences foam stability and conditioned soil behavior, and how atmospheric test results must be viewed in the context of expected chamber pressures. Torsional shear strength, compressibility and abrasivity of foam conditioned sand were found to be ideal when the void ratio was above the ASTM-determined maximum void ratio, achieved by sufficiently expanding the soil grain structure with foam, herein when the foam injection ratio at pressure exceeded 45%. Otherwise, the engineering properties of foam conditioned sand were not ideal, i.e., appreciable torque and abrasivity, low compressibility. INTRODUCTION Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. The formation soil at the cutterhead must be transformed into a highly compressible, low shear strength and low permeability medium within the excavation chamber to allow effective EPB performance. This behavior must be maintained for a certain residency time while the soil is in the chamber and screw conveyor. The vast majority of published studies on conditioned soil behavior have been performed under atmospheric conditions (Quebaud et al., 1998; Bezuijen et al., 1999; Psomas and Houlsby, 2002; Vinai et al. 2008; Thewes et al., 2012; Peila, 2014); however, the desired soil behavior must occur under chamber pressures that can reach 5-7 bar. The influence of pressure on conditioned soil is significant and is dramatically different than behavior under atmospheric pressure (Williamson et al., 1999; Mori et al., 2015). This paper illustrates how pressure influences conditioned soil behavior and how atmospheric test results must be viewed in the context of expected chamber pressures. The influence of pressure on foam bubble size (including with time) is shown through digital image analysis. The influence of pressure on foam half-life is also investigated. The compressibility, shear strength, and abrasivity of conditioned soil under pressure is presented and explained in terms of density, soil and air compressibility and porosity."

Jan 1, 2016

By Isobel Yeo, Luca Cocchi, Sven Petersen, Nico Augustin, Sean Plunkett, Ingo Klaucke

Exploration for seafloor massive sulfides is currently mainly focused on investigation for active hydrothermal vent fields. However, most of the resource potential is thought to be related to inactive, large deposits that had enough time to accumulate sufficient tonnage. At the same time, ageing of these deposits will ultimately result also in burial acted by either sediments and/or volcanic deposits. We currently lack the technologies to explore for these deposits in a time- and cost-efficient manner. In the fall of 2012 we used a number of AUV-based technologies to explore and image a sulfide occurrence at the Palinuro Volcanic Complex in the Tyrrhenian Sea (Mediterranean Sea; Fig. 1) where sampling and drilling have documented a buried polymetallic barite-pyrite dominated site (Petersen et al., 2014). Sulfide mineralization is here covered by volcaniclastic and pelagic sediments and only red sediment staining and the presence of few tubeworm bushes indicated recent hydrothermal activity - black smoker venting is absent. We used AUVbased high-resolution bathymetry, sidescan sonar imaging, subbottom profiling, as well as magnetics to describe, in a quantitative way, the previously known sulfide-bearing areas as well as to successfully explore for new hydrothermal sites including large chimney structures (Figs. 2). Additionally chemical sensors (CTD, Eh, turbidity) investigated the water column for signs of hydrothermal activity in areas not previously investigated, but at the end, only weak anomalies were found in the southern part of the summit.

Sep 1, 2014

By Janet A. Johnson, T. B. Borak, K. J. Schiager

INTRODUCTION In the USA regulatory agencies have adopted standards which limit the allowable concentration of ore dust in underground uranium mines. The American Conference of Governmental Industrial Hygienists has recommended a threshold limit value for silica which has been incorporated by reference in federal regulations (30 CFR 57, 1980). The Nuclear Regulatory Commission (NRC) imposes a limit for unprocessed uranium ore dust for reducing the exposure to radioactive materials from inhalation (10 CFR 20, 1980). We have been unable to trace the origin of the NRC standard. Recently the ICRP has published recommendations concerning limits for intakes of radionuclides by workers (ICRP, 1979). We have used the ICRP methodology to compute the dose equivalent commitment to lung and bone from inhalation of insoluble ore dust particles. These values were used to derive air concentrations which would provide an acceptable risk for induction of cancer from occupational exposure. Results indicate that the new ICRP recommendations are more restrictive than the present NRC standard for radioactivity. The maximum allowable dust load in a uranium mine will depend on both the concentration of silica (% Si02) and the amount of radioactivity (% U308). We have combined these standards assuming complete independence of biological hazard to establish boundary conditions for which either silica or radioactivity is the dominating factor. Based on these results we present suggestions for analysis of ore dust to insure compliance with regulatory agencies. SILICA STANDARDS Silicosis, fibrotic lung disease produced by crystalline silica, was one of the earliest forms of occupational disease to be recognized. The pulmonary lesions caused by silica, silicotic nodules, consist of concentrically arranged bundles of collagen fibers. Fusion of these nodules results in progressive massive fibrosis causing alveolar changes which decrease ventillation and blood flow in the lungs. The current Threshold Limit Value (TLV) for mineral dusts is based on the concentration of free silica. The standard is expressed in three forms: (1) Particle count standard: TLV (mppcf) = 300/(% Si02 + 10) (mppcf = million particles per cubic foot) (2) Respirable dust mass standard: TLV (mg/m3 ) = 10/(% respirable Si02 + 2) (3) Total dust standard: TLV (mg/m3 ) = 30/(% Si02 + 3) The most commonly used form is the respirable mass standard. These curent values for silica are based primarily on epidemilogical studies of Vermont granite workers and other occupationally exposed workers. In the Vermont study no cases of silicosis were seen in individuals employed after dust control measures were initiated and whose subsequent exposure averaged less than 5 mppcf. The free silica concentration in the airborne dust to which these workers were exposed averaged 25%. A concentration of 10 mppcf of granite dust is considered equivalent to 0.1 mg/m3 quartz. The current respirable mass standard allows a maximum silica concentration of 0.1 mg/m3. NIOSH (1974) has recommended a reduction in the current TLV for respirable silica to 0.05 mg/m3 Si02. As with radiation standards, the TLV for mineral dusts is an upper limit for time weighted average exposure. It is recommended that dust concentrations be maintained as far below the TLV as current practices permit. RADIATION STANDARDS The present concentration limit for airborne natural uranium in ore dust prior to chemical separation is 75 µg of uranium per m3 of air ( 10 CFR 20, 1980) . This corresponds to 1.85 Bq/m3 (50 pCi/m3 ) of natural uranium, U-238, U-235 and U-234 and is equivalent to 3.7 Bq/m3 (100 pCi/m3 ) of gross alpha activity with radioactive equilibrium between the long-lived alpha progeny through Ra-226. The origin or basis for this standard is not known, but it presumably includes both chemical toxicity and risk from somatic radiation injury. Recently the International Commission on Radiological Protection (ICRP, 1977) has published recommendations concerning the objectives and criteria for limiting radiation exposures. This was followed b y a revision of the limits for intake of radionuclides by workers (ICRP, 1979; ICRP, 1980). The previous compilation of limits for internal emitters was published by ICRP Committee II in 1959 (ICRP, 1959). The latest version includes new methodlogy outlined in ICRP Publication 26 (ICRP, 1977) as well as extensive metabolic information

Jan 1, 1981