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By GRANT COLLIGAN, BROCK O’KELLEY, Corby Anderson

With the world’s ever-expanding push to expand technological capabilities, the need for specialized materials including rare earth elements has exploded. One source found in the USA is bastnaesite, a rare earth bearing fluorocarbonate mineral, currently mined at the Mountain Pass Mine in California. To increase production, it is essential to optimize existing processes and create new ones to better utilize current resources. Therefore, a US Department of Energy Critical Materials Institute sponsored research program was carried out at the Kroll Institute for Extractive Metallurgy to expand the fundamental understanding of the industrial bastnaesite concentrate leaching system. With the help of prior knowledge, thermodynamic calculations and design of experimentation based lab testing, a novel single-stage hydrochloric leach system was created to optimize the rare earth extraction from bastnaesite. Historically, the existing industrial process has utilized a two-stage leach system involving a high-temperature hydrochloric acid leach with liquid solid separations followed by a caustic crack stage of the leach residues. A series of single-stage leach experiments were run by reacting locked cycle flotation concentrates with hydrochloric acid to test common leaching parameters. The results of these patent pending single-stage tests have shown rare earth recoveries significantly higher than reported recoveries of historic two-stage caustic crack processes, all while decreasing the equipment required and the type and amount of reagents needed.

Jan 31, 2022

By Pieter-Jan Kleiterp

Highwall mining is a mining method to extract coal from a final boundary in opencut mining, trench mining or contour mining. This boundary may have been reached because of economic constraints (economic strip limit) or geographic constraints, such as spoil heaps and rivers. Coal is mined from visible, horizontal, or near-horizontal coal seams by making rectangular, parallel, unsupported drives with an unmanned cutterhead and coal transport system. This is controlled from a mining unit, or launch frame, positioned outside the drive, in front of the highwall. Removal of overburden is not required or is limited to small quantities only.

Jan 1, 2010

By VÍCTOR VÁZQUEZ-VÁZQUEZ, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, JESÚS L. VALENZUELA-GARCÍA, OFELIA HERNÁNDEZ-NEGRETE

This study examines a process for the recovery of precious metals from difficult minerals that exhibit refractory characteristics to cyanidation: low extraction of metals and high consumption of leaching reagent. A mineral sample from Monte del Favor Mine, located in Hostotipaquillo, Jalisco, Mexico, was physically and chemically characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fire assay and atomic absorption spectroscopy (AAS). Two stages of leaching were carried out, first to eliminate manganese from the sample using sodium sulfite (Na2SO3) as a reductive reagent along with sulfuric acid (H2SO4), and second to dissolve gold and silver with hydrochloric acid (HCl) and sodium hypochlorite (NaClO). The results show extractions of around 96 percent for manganese (Mn), 98.73 percent for silver (Ag) and 83 percent for gold (Au). The usefulness of high acidity and Na2SO3 to obtain better results in Mn and Ag leaching are discussed along with the roles that HCl and NaClO play in Ag and Au dissolution values.

By C. Manea

During exploration and exploitation of complex ores, waste dumps that contaminate severely the environment and in particular soils, are genetated. The most hazardous pollutants are heavy metals and metalloids (e.g As, Mo, Pb and Cu) as well as radionuclides (e.g U and Ra). Ecological remediation aims, among others, at decontamination of soils by preserving important properties as soil fertility.

Jan 1, 2008

By Guillermo P. Salas

The Consejo de Recursos Naturales No Renovables of the Mexican government entered into an agreement with the United Nations in 1964 for the mineral exploration of a large area in Estado de Sonora, Mexico. The agreement called for a systematic exploration for copper in northern Sonora based on photogeologic mapping, aerial reconnaissance, and geochemical stream sediment sampling. The UN-CRNNR investigations resulted in the detection of anomalous copper values in sediment from the Arroyo Cruz de Cafiada. The anomaly was followed upstream to its source, which ultimately proved to be the La Caridad ore body (see Fig. 1). Soil copper and molybdenum values were found over a large area, and further detailed geologic and geophysical investigations were instituted of the anomalous area. David Coolbaugh was largely responsible for the follow-up work. An induced polarization (IP) survey found a roughly circular region of "highs" that coincided with a high soil copper anomaly. The circular anomalies ringed the topographic feature that ultimately was found to contain the Caridad ore body. Soil geochemical copper response over the ore body was subdued, because the soils were derived from a leached capping, whereas leaching in fringe areas that contained less veining was less intense. The ore body was also ringed by the typical high pyrite zone, and this was the anomaly detected by the IP survey. The UN began drilling in the fall of 1966. Eleven holes tested the IP-Cu geochemical high, but none were of commercial interest. The project was returned to the Consejo and was reviewed in the field by G.P. Salas and V.F. Hollister. It was found that the leached capping had not been tested by the past activities, and the Consejo elected to explore that area in 1967. The capping was evaluated by Salas and Hollister and drilling by the Consejo began in 1967. Commercial grade ore intercepts were found in the first hole. The Consejo drilled nine holes, of which eight were commercial. At least 90.7 Mt (100 million tons) of 0.8% copper were indicated by the Consejo in eight holes. The lesson learned in this discovery is that evaluation of leached capping is an important guide to exploration. The general-

Jan 1, 1991

By Walter E. Heinrichs

This case history really started during the tail end of WWII when two Navy men, both Colorado School of Mines graduates, got together in Washington, DC, while they were assigned to the Office of Navy Petroleum Reserves doing some of the first aerial magnetometer work ever done on a practical oil exploration basis over the offshore area of the Gulf Coast. When separated from Naval Service active duty in 1946, the two men, Walter E. Heinrichs, Jr., and Robert E. Thurmond, tried, unsuccessfully, to form a commercial air magnetometer business. Later they got together again in Jerome, AZ, with Newmont Mining's early geophysical exploration endeavors from 1947 to 1949. Subsequent to the Newmont experience, they jointly proposed a specific mining geophysical exploration and development program to Herbert Hoover, Jr., then president of United Geophysical Co. of Pasadena, CA. Mr. Hoover, in consultation with his father Herbert Hoover and others of his staff at United, particularly Edwin G. Schempf, executive vice president, and Raymond A. Peterson, vice president of research, agreed to establish the proposed program under United's auspices, to be headquartered at Tucson, AZ. The primary objective would be to practically test and develop various mining geophysical methods and techniques while exploring particularly for base metals in the general area of southeast Arizona and southwest New Mexico.

Jan 1, 1991

By H. Maleki

This paper recognizes the 100th year of research accomplishments by the mining industry resulting from close cooperation among mining companies, geotechnical consultants and researchers from the former United States Bureau of Mines in stability assessments and development of improved and productive mine designs. The paper provides an overview of dramatic developments in geotechnical instrumentation, and its applications in the U.S. and around the world for enhancing the understanding of ground response to mining-induced changes in stress, resulting in improvements in ground control technologies.

Jan 1, 2010

By M. Misra, I. Anazia

The dispersion of oily collector has a significant effect on the flotation recovery of ultrafine coal. Generally, reagent dispersion is accomplished by mechanical mixing and/or ultrasonic agitation, followed by direct addition of dispersed collector into the flotation cell. Such dispersion and reagent addition techniques are invariably inadequate and nonselective. A new collector addition technique involving gas phase transport of atomized collector has shown improved results when compared to conventional reagent addition techniques. This technique involves atomization of the collector into the air stream. Under these circumstances, an aerosol is introduced into the flotation cell. Initially, the oil is dispersed within the air phase (continuous with respect to oil), and the air phase is dispersed within the pulp (continuous with respect to aerosol). In the flotation cell, the atomized oil droplets coalesce on the bubble's surface and create a de facto oil-encapsulated bubble. This approach provides excellent dispersion, increases selectivity, and, most significantly, increases the flotation rate of ultrafine coal. Atomization of collector/frother combinations yielded improved flotation recovery and maintained near uniform froth levels, which is a desirable feature in coal flotation. Microscopic examinations of the attachment of oil- coated bubbles at a coal surface were conducted by attachment time and contact angle measurements. Oil-coated bubbles attach at significantly faster rates and with a higher contact angle than oil-free bubbles.

Jan 1, 1988

By Taner Aydogmus

The A$29 billion Chevron-operated Wheatstone Project is one of Australia’s largest resource projects. Located at Ashburton North, 12 kilometers west of Onslow in Western Australia, the project will consist of two Liquefied Natural Gas (LNG) trains with a combined capacity of 8.9 million tons per annum and a domestic gas plant. The LNG Plant will serve the offshore gas fields, which are situated some 250 km off the coast of Onslow in Western Australia. Once operational and on-stream, the Wheatstone Project will contribute to Australia becoming the world’s second largest exporter of LNG. For crossing the environmentally sensitive shore area, a micro-tunnel with an internal diameter of 2 m and approx. 1,242 m in length has been constructed by means of the pipe-jacking method. The micro-tunnel will accommodate a 1.1 m diameter pipeline (trunkline) to deliver gas from the offshore fields LNG Plant. The Wheatstone shore crossing design involves a number of unique challenges owing to its coastal location, where the alignment crosses through a shore area and terminates in a marine environment. This paper provides an overview of the Wheatstone Shore Crossing Project, presents the key features, and discusses the main aspects of the micro-tunneling design.

Jun 13, 2021

By Patrick J. Doig

The Crosstown 7 Collector System, Contract C28G11, is part of the Milwaukee Metropolitan Sewerage District's Waste Pollution Abatement Program. The contract involves the construction of 1.6 km (1 mile) of 3 m (10 ft.) diameter tunnel in soft ground. The tunnel is 10 m (35 Ft.) below surface and passes through a variety of soils. The eastern leg of the tunnel along Bruce Street is mainly in till material, a stiff, relatively dry clay. The northern leg along 16th Street starts in till, and continues in estuarine deposits - moist sticky clay, with intrusions of alluvial sand and gravel. The contract specifications required that the tunnel be constructed either under compressed air or with an earth pressure balance tunnel boring machine. The S. A. Healy Co., the general contractor, chose the latter option. Additionally, a single pass, pre-cast concrete segmental liner was selected as the lining system. The mining machine was manufactured by Lovat Tunnel of Canada and the segments were made by the Sehulster Company of Milwaukee. The use of this combination of machine and lining is relatively new to the United States and this tunnel is the most extensive built to date with a gasketed, segmental single pass lining for transportation of fluids. This paper details the various aspects of the construction of the tunnel and associated shafts.

Jan 1, 1989

By Kevin Schraden, Andrea Pezzi

environmental and social/political changes the world is currently experiencing. Three of major challenges facing the mining industry today are: water scarcity, unpredictable weather conditions that generate a risk of tailings dam failures as well as the correlating social pressure and government regulations that prevent the development of new or expanded tailings dam projects. It is estimated the total number of active, inactive and closed storage facilities globally is over 8,500 containing over 217 km3 of tailings (46% are from copper mining)1 which at some point will need to be addressed. Technologically, there are several solutions for tailings management, including conventional ponds, thickened tails, paste backfill and filtered dry stack tailings. The use of pressure filters, for tailings dewatering is currently being evaluated and often selected as the preferred technology where dry stacking is the chosen solution for residue disposal. This is mainly due to the pressure filters ability and flexibility to address and achieve the current challenging aspects of tailings processing including: • Extremely high capacities of >80,000 dry tons/day • Lower ore grades which require finer grinding and result in a higher amount fine fractions and clay content • Residual moisture targets required for the geotechnical specifications for dry stacking

Feb 1, 2024

Vancouver-based War Eagle Mining Co. is an advanced-stage Canadian junior mining company that is focused on becoming one of the world?s leading germanium producers. War Eagle?s primary focus is on the Tres Marias high-grade germanium mine near Chihuahua, Mexico. The Tres Marias Mine has high-grade zinc mineralization as well. War Eagle acquired the 28-km2 (17.4-sq mile) property in 2001 from Tombstone Exploration and is currently working to put the mine into production. Current exploration is focused on supporting a resource report and prefeasibility study that is expected to be completed in early 2008. War Eagle expects to have completed an estimated 80 underground diamond drill holes, 40 surface diamond drillholes, 31 percussion holes and 1,296 1.5-m (5-ft) channel samples. Eighty-seven additional exploration targets have been identified within the mining concession. Recent drill results have significantly expanded the known mineralized body at the Tres Marias Mine. The exploration and development program is expected to be completed during 2008. War Eagle owns both the drills currently in operation at Tres Marias. An advanced exploration and development program has confirmed historical grades and is producing encouraging new results from diamond and percussion drilling, channel sampling and high-resolution resistivity geophysics. Glenn R. O?Gorman, an independent geologist and consultant to War Eagle, conducted a study on the reporter. He stated that the Tres Marias concession area has the potential to host 5 to 10 Mt (5.5 to 11 million st) of minable ore.

Jan 1, 2008

By D. Randall Crooke, Ron R. Jorgenson

Many coal combustion products (CCPs) have historically been unsuitable for placement as mine backfill because of their physical and geochemical properties and/or regulatory status. However, innovations in paste production and transport of CCPs utilizing the high, fine particle contents of these fine-grained waste materials and their water retention colloidal properties produce a non-segregating, self-cementing material that may be environmentally suitable for placement as mine backfill. Both industry and the regulatory agencies are enthused by the possible cost reductions, both in design and construction of disposal sites, and the reduced environmental impacts of CCP realized by implementation of this new use/disposal technology.

Jan 1, 2001

By Crystal Poon, Paul Matlashewski, John Morkeh, Kathryn Dorfschmidt, Jose Carvalho, Chad Williams

Rockfall hazards are ubiquitous in mining environments making their control critical for safe mining operations. The complex processes involved in rockfall events necessitate a probabilistic modeling approach with well-calibrated material properties. The controls designed to mitigate rockfall hazards need to be reliable, efficient, and safe to deploy to meet the constraints present at an active mine. This paper presents an innovative solution to rockfall at Rio Tinto’s Bingham Canyon Mine. The solution incorporates the site-specific calibration and creation of a predictive rockfall model with the design, field testing, implementation, and monitoring of the rockfall controls.

By Saurav Kumar, Akshay Kumar, Vinayaka R. Kiragi, M. K. Banerjee, Amar Patnaik, Vinod Kumar

Today’s industrial technology offers to optimize and reutilize the resources available in terms of scum that remains after hot rolling in steel rerolling mills in Rajasthan, India. Vast reserves of low-grade coal exist and tons of mill scale are produced everyday after hot rolling in steel rerolling mills in Rajasthan, India. The present research work aimed to optimize the various parameters of solid-state reduction of mill scale using low-grade coal from Rajasthan, India. This study investigates the effect of reduction temperature (850–950 °C in steps of 50 °C), reduction time (60 to 180 min, in step of 60 min), mill scale size (800– 300 μm), and mill scale to coal ratio (1:1, 1:2 and 1:3) on achievable metallic iron percentage and its metallization. A higher percentage of iron content is obtained at a lower particle size of 300 μm. The structural analysis is carried out on 300 μm mill scales using XRD analysis, which shows the percentage of iron is approximately 63%, and metallization above 80% can be obtained under the reduction temperature at 900 °C for 180 min, for 1:3 ratio (mill scale to coal ratio). The chemical composition of the mill scale is obtained using X-ray fluorescence (XRF), and particle sizes as well as distribution of mill scale are determined by scanning electron microscopy (SEM). The elements present in the mill scale are also verified using EDS, which indicates the presence of a major portion of Fe, followed by Fe2O3, Si, and C, respectively.

Aug 14, 2020

By Eugene F. Casey, John G. Ruggiero

INTRODUCTION Construction of tunnels in urban areas, especially reclaimed areas, pose many problems. The Red Hook Intercepting Sewer Tunnel, Contract 1A is a portion of the Red Hook Water Pollution Control Project located along the Brooklyn waterfront in New York City. This contract required the construction of a 2620 meter long (8600 L.F.), 3 meter (10-foot) diameter soft ground tunnel, eight Tunnel Manholes, nine Regulator structures, four Diversion and Tidegate structures and 765 meters (2500 L.F.) of branch intercepting sewers of diameters between .30 meters (12 inches) and 1.8 meters (72 inches). The construction contract bid price was $62 million with a duration of three years. The tunnel route crosses over five sets of operational twin cast iron subway tubes with clearances ranging from 4.3 meters (14 feet) to as small as 0.35 meters (14 inches). The route of the tunnel traverses historically interesting areas which have been reclaimed over the last 200 years. This paper is a case history describing the contractor's methods utilized to successfully advance the work through the above problem areas. LOCATION The Red Hook Intercepting Sewer Tunnel is located in the Borough of Brooklyn of New York City. The route is

Jan 1, 1981

By Steven E. Mischler, Jay F. Colinet

The Mine Safety and Health Administration (MSHA) promulgated a rule in 2014 that required numerous changes in compliance dust sampling requirements for coal mine operators. Two key parts of this rule were the lowering of the respirable coal mine dust standard from 2.0 mg/m3 to 1.5 mg/m3 and requiring operators of underground coal mines to use a continuous personal dust monitor (CPDM) for compliance sampling. The CPDM currently approved for compliance sampling is equipped with a display that provides miners with in-shift information on their respirable dust exposure. The goal was to provide an indication of a potential overexposure and empower the miner and mine operator to implement changes in controls and/or operating practices to prevent an overexposure from occurring.

By P. K. Kaiser, M. Cai

When designing an efficient and effective support system for burst-prone ground, it necessary to select the most appropriate, i.e., the ‘right’ support components, including areal and reinforcement components. For this paper, it is assumed that the areal support is not the weakest link and the support performance is controlled by the rock reinforcement and holding components (bolts). We discuss the loading modes of rockbolts under static and dynamic loadings and analyze published data from laboratory and field tests. The mechanisms of energy absorption of dynamic rockbolts are presented and rockbolts are categorized based on factors such as energy absorption capacity, energy absorption rate, direct and indirect energy absorption capacities, rock mass bulking or displacement control, and shearing resistance capacity. Guidelines for selecting the ‘right’ rockbolts to build an effective rock support system for burst-prone ground are provided.

Apr 26, 2022

By Luis Pommier

In the United States, about one-quarter of the fuel oil and natural gas consumption is associated with power production in utility and industrial boilers and process heat needs in industrial furnaces. Coal has been an attractive candidate for replacement of these premium fuels because of its low cost, but there are penalties associated with the solid fuel form. In many cases pulverized coal is unacceptable as a premium fuel replacement because of the extensive cost of retrofitting an existing boiler designed to burn oil or gas. In the cases of synthetic fuels from coal, research and development still has a long way to go and the costs of research and development are very high. Another option which appears very attractive is the use of solid coal in a liquid fuel form, coal slurry fuels. Occidental Research Corporation (ORC) has been developing coal slurry fuels in conjunction with Island Creek Coal (ICC,) Occidental Petroleum's wholly-owned subsidiary. Both Coal-Oil Mixtures and Coal -Water Mixtures are under development. ICC is a large eastern coal producer, engaged in the production and marketing of bituminous coal, both utility steam and high quality/low volatile metallurgical coals. A sister division, Sheridan Enterprises is engaged in the development of western coals.

Jan 1, 1983

By J. Noll, A. Miller, J. Volkwein, C. Pritchard

Hecla Limited, Magee Scientific and the U.S. National Institute for Occupational Safety and Health (NIOSH) combined efforts to evaluate an in situ air filtration system for use in an underground mine environment. The purpose of the collaboration was to determine the efficacy of such a technology for reducing the concentration of airborne diesel particulate matter (DPM), with the aim of improving air quality in underground hardrock mines. A secondary goal was to evaluate the use of an aethalometer as a means of real-time measurement of black carbon as a surrogate for DPM. The evaluation included measuring the DPM-capture efficiency of the filter when it was preloaded with dust. Toward this end, rock dust was introduced at the filter inlet to create a dust layer on the filter surface, with the intent of providing improved capture of the much smaller DPM particles. The filtration efficiency for DPM was assessed by comparing measurements of DPM taken at the inlet and outlet of the system, using both realtime and time-weighted-average approaches. The real-time measurements were performed with a Model AE33 aethalometer, and filter samples analyzed by the NIOSH 5040 method were used to assess the effects of the system on time-weighted-average concentrations of total carbon. Results showed a reduction in DPM concentrations in the range of 82 to 89 percent. While the calculated efficiencies based on the two different measurement methods were similar, the DPM levels reported by the aethalometer were higher, possibly due to differences in the performance of the size selectors used for the two methods: impactors versus cyclones. More research is required to develop a robust correlation between the two methods to support the use of the aethalometer in future mining applications. The advantages of the aethalometer are that it can measure and record DPM levels for weeks at a time and can be directly connected to a mine monitoring system, potentially at multiple locations. Ideally, such data can be used to initiate the startup of the filtration system should DPM concentrations reach an action level. This work demonstrated that in situ filtration systems, modified to collect DPM and coupled with real-time monitoring, show promise in reducing DPM concentrations in the mine environment.

Mar 1, 2017