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By Dan Swidrak, Bill Zietlow

Halfway through a 17,770-ft long stormwater tunnel, an 11-ft diameter TBM encountered a karst void below the Mississippi River in Missouri, resulting in significant inflow. It was decided that the TBM could not safely advance without external intervention. Low-mobility grout was pumped from the surface. A rescue shaft was constructed and a conventional tunnel with spiling support was mined back to the machine. The TBM was removed and a 14-ft diameter TBM equipped with probing drills was relaunched. Probing from the new TBM encountered one additional karst feature but the machine advanced after grouting and successfully completed the tunnel.

Jun 23, 2024

By Errol vanHuyssteen

Old tailings from Zn, Au, Cu, and Ni mining operations were characterized. Their mineralogical variation in depth is compared with matching pore water and solids chemistry. A geochemical model was used to predict minerals precipitating from pore water solutions. These are compared with actual secondary minerals occurring. The degree to which the precipitation of secondary minerals controls the sulfate and iron concentration of the pore water was also investigated. The results obtained are related to the selection of the most appropriate modes of tailings deposition.

Jan 1, 1998

By Graham J. Morgan

The following material is excerpted from a presentation Mr. Morgan gave recently to representatives of the financial community. Introduction 1982 was a period of challenge for United States Gypsum Company because of reduced market opportunity. Housing starts for the first 10 months averaged a seasonally adjusted annual rate of 1 million units, 9% below the comparable 1981 period when housing starts were the lowest in 35 years. Industry gypsum board shipments declined 9% from the already low levels of the same period in 1981. US Gypsum met the challenge with stringent cost reduction programs and aggressive action in the marketplace. In late 1981, anticipating market deterioration, the company's management adopted strategies to focus on two shortterm objectives: • Adjust operations to perform profitably in view of limited opportunities through more efficient operations and asset management. • Continue to strengthen U.S.G.'s resources and ability to take advantage of important market opportunities as the economy improves through selective expansion of production capacity in key growth markets. Concentration on these two objectives resulted in a nine month performance in 1982 that, while certainly not satisfactory by company standards, compared very favorably with that of principal competitors in terms of net earnings, margin on sales, and return on average stockholders' equity. To counteract limited market opportunities, U.S.G. focused on productivity improvement, cost reduction, expense control, and maximization of market penetration. Energy Use Improving performance encompassed all segments of operations. For example, efficient use of energy was a significant factor despite lower operating rates at most plants. Overall, in the third quarter of 1982 versus 1972, the company used 27% less energy per unit of production, a savings of $15 million in that quarter alone. These continuing improvements helped to partially offset constantly rising energy costs. A number of operations achieved superior results in the first nine months of the year compared with the same period in 1981. For example, gypsum board plants in Jacksonville, FL, and Sweetwater, TX, recorded 8% and 7% reductions, respectively, in energy use per unit of production. Paper mills in Oakfield, NY, Galena Park, TX, and Kansas City, MO, each reduced energy use more than 12%, while the Greenville, MS, ceiling products facility achieved a 16%o reduction. Safety Safety is another important element that received increased attention. U.S.G.'s safety performance over the past five years has consistently improved. In 1981 it was five times better than that of the gypsum industry; nearly 10 times better than all industry as measured by the National Safety Council; and almost 20 times better than all US manufacturing as recorded by the Bureau of Labor Statistics. In addition to human concerns, this excellent record results in significant dollar savings that directly affect company results. In 1981, U.S.G.'s pre-tax savings in claims, premiums, and related expenses were about $20 million compared to the industries in which it competes. For the first half of 1982 performance improved further, with a cumulative lost workday incidence rate per 200,000 man-hours worked of only 0.27, an all-time record. Expense Control Careful control of inventories and receivables also received special attention. As of Sept. 30, 1982, inventories were 29%, or $44 million, below the level of Sept. 30,

Jan 2, 1983

By V. E. Housman

EPA's Office of Solid Waste (OSW) is developing a program, under Subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate the management of non-coal mining wastes. In May 1988. OSW produced a "Strawman", which is a working document that is precursor to a proposed rule. OSW has been working closely with environmental groups, industry, and States to solicit comments and feedback on the mining waste program. OSW currently plans to release a second "Strawman" in early 1990. A proposed rule is tentatively scheduled to be published in the spring of 1991.

Jan 1, 1990

By C. B. Henderson

The development of slurries of coal and water as a boiler fuel replacing No. 6 fuel oil has been actively pursued at the Atlantic Research Corporation since 1976. Funding for this effort has been provided by the U.S. Department of Energy, the Electric Power Research Institute, and by corporate funds. The name ARC-COALTM has been selected for these slurries. Stable coal-water slurries with bone-dry coal loadings between 62% and 77% have been prepared, evaluated rheologically, and successfully burned in an experimental furnace without the assistance of other fuels. The advantages and properties of these slurries, including combustion results, are reviewed. Also discussed is the pilot line used for processing barrel quantities of fuel and a pilot plant capable of processing 600 bbl/day, currently being designed.

Jan 1, 1982

By C. P. Boddy

One of the most difficult tasks a project manager will have in pre-mine planning is dealing with the mine site's hydrologic regime. Numerous federal statutes passed by Congress in the last decade have made the coal mining industry more responsive to the environmental impact during all phases of the mining process. Permitting these mines has dictated a cradle to grave approach in dealing with water related issues. This paper will attempt to explore the application of these technology- based laws and their direct application to the unique environment found in Alaska's interior regions.

Jan 1, 1985

By Sunny Schoone, Maximilian Getz, Felix Leaman, ELISABETH CLAUSEN

Hydraulic transport is commonly used in mining for moving particles or ore concentrates in pipes over long distances with a water stream. Control and monitoring of this process require sensor technology that can obtain relevant characteristics of the two-phase flow. This work investigates the acoustic emission (AE) technology for monitoring a hydraulic system with different sand concentrations, showing the strong relationship between friction behavior in the pipe and the measured AE signals.

Apr 1, 2023

By RIINA SALMIMIES, ANTTI HAKKINEN, PAULA VEHMAANPERA

Better understanding of the mechanisms and kinetics of dissolution can benefit several industrial processes. For example, iron can be leached from clays, which can be further used as a raw material in the ceramic industry. Another important application is the regeneration of ceramic filter media, which are used in the dewatering of iron ores. Dissolution of iron oxides in mixtures of acids is fairly uncommon and a less well-understood phenomenon, but it can result in a more efficient process. This work also shows that the determination of dissolution mechanisms and kinetics is not straightforward in different acid systems.

By G. Akdogan, S. M. Bradshaw, A. P. Van Wyk, T. Punt

This study investigated the performance of citric acid as lixiviant for cathode material from end-of-life lithium-ion batteries (LIBs). Black mass containing 84.2 weight percent MNC (LiNi0.45Mn0.4Co0.15O2) and 15.8 weight percent LCO (LiCoO2) material was leached at solid-to-liquid ratios of 20, 50 and 100 g/L. Leaching with 1.5 M citric acid, 2 volume percent H2O2 and a solid-to-liquid ratio of 20 g/L at 95 °C extracted 90 percent Co, 95 percent Li, 94 percent Mn and 94 percent Ni within 20 min. At the highest solid-to-liquid ratio of 100 g/L with 1.5 M citric acid, 10 volume percent H2O2 and 95 °C, 84 percent Al, 84 percent Co, 87 percent Li, 86 percent Mn and 96 percent Ni were leached after 40 min, producing a leach solution containing 0.68 g/L Al, 20.0 g/L Co, 6.0 g/L Li, 13.6 g/L Mn and 19.3 g/L Ni. Using stepwise addition of H2O2, instead of initial bulk addition, did not significantly improve the leaching efficiency but did reduce the required leaching time. Temperature control of the reactor was also more manageable with stepwise addition of H2O2, and evolution of gas was less vigorous. It was observed that the leaching efficiencies of Co, Li and Mn decreased slightly at solid-to-liquid ratios of 50 and 100 g/L, while the leaching of Ni increased slightly. The solution leached at 20 g/L could be stored for six weeks without any spontaneous precipitation. However, solutions leached at 50 and 100 g/L showed changes in concentration after one month of storage, suggesting that processes that have a large material throughput and use high solid-to-liquid ratios around 100 g/L must ensure that the solutions are not stored for extended periods of time.

Apr 1, 2025

By L. Yuan, D. Bahrami

Underground mine fires remain a concern for mine operators, posing a health and safety risk to mineworkers. In the last decade, the number of mine fires has decreased significantly. However, dealing with an unknown fire in underground mines can be a challenging task, which could lead to a hazardous condition for miners during an evacuation and rescue operation. A timely detection of a mine fire and monitoring its characteristics—namely, size and location—are of great importance in reducing the risk of mine fire injuries. A new, improved fire location algorithm has been developed and integrated into an atmospheric monitoring system (AMS) program by researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH). This paper describes the new fire location model and presents the results of verification fire tests conducted at the Safety Research Coal Mine (SRCM) facility of the Pittsburgh Mining Research Division (PMRD) using the collected AMS data. NIOSH is endeavoring to develop workplace solutions to improve the detection of and reduce the risk of hazardous conditions in mines. The results demonstrate successful application of the improved fire location model and provide a useful tool for solving the problem of unknown fire location and reducing the risk of hazardous conditions.

By D. R. Kelland

A program has been carried out over the last two years to apply the technology of High Gradient Magnetic Separation (HGMS) to the problem of mineral beneficiation and specifically oxidized taconite iron ores. This program, supported by the RANN division of the National Science Foundation, has consisted of a laboratory program at the Francis Bitter National Magnet Lab- oratory at MIT and a pilot investigation at the Hanna Mining Company Research Laboratory. 1 The laboratory tests were conducted using several batch type high gradient separators and a continuous separator with a rotating matrix which was constructed at the beginning of the program. The high field magnets available at F.B.N.M.L. were used for investigations above 10 kG but most of the test work was performed in the range of this field value. Ore samples were contributed by several iron ore companies and consisted of oxidized taconites having goethite and hematite as their principal components.

Jan 1, 1975

By Edward J. Sterne

Several shale-hosted Pb-Zn-Ag deposits have been discovered in the northwestern Brooks Range, Alaska. Best known among these are the Red Dog, Drenchwater Creek, Lik, Ferric Creek, Hot Dog Creek, and Competition Creek deposits. They occur in a tectonically disturbed sequence of of Mississippian to Triassic shales, argillites, and cherts, and most are spatially associated with volcanic rocks. The sulfides are hosted in shales as disseminations, banded layers, massive lenses, and crosscutting veins. Detailed geologic descriptions of sulfide prospects in the Brooks Range were given by Tailleur (1970), Nokleberg and Winkler (1978), and Plahuta and Robinson (1979). Lange et al. (1980) discussed the formation of the deposits, the nature of the mineralizing solutions, and the temperature of formation on the basis of sulfur isotope studies. More recently, Harrover et al. (1982) detected a correlation between sulfide mineralization and high-temperature formation of charts associated with the sulfides by oxygen Isotope and chert crystallite size determinations.

Jan 1, 2013

By Nicholas T. Esposito

An advanced coal preparation plant has been built at Homer City, Pennsylvania, by Pennsylvania Electric Company, a subsidiary of General Public Utilities Corporation, and New York State Electric and Gas Corporation, as an alternative to utilizing flue gas desulfurization technology to meet the Federal Environmental Protection Agency and the Pennsylvania Department of Environmental Resources air quality emission regulations of 4.0 lb S02/106BTU for the two (2) existing coal-fired generating station Units No. 1 and No. 2, and a 1.2 lb S02/106BTU for the new Unit No. 3. The coal preparation plant is designed to process 5,200,000 tons of run of the mine coal annually and has a design capability to process 1,200 tons per hour via two (2) equal capacity 600 tons per hour preparation circuits.- The plant is designed to produce multi-product coal streams consisting of a middling product of medium ash and medium sulphur content, which is environmentally compatible to support operation of the two (2) existing generating Units I and 2, and a deep cleaned, low ash, low sulphur coal product capable of environmentally supporting the ambient air quality requirements of the new Unit 3 generating facility. The waste product from the process consists of high ash, high sulphur reject material. The process has the acronym MCCS (Multi-Stream Coal Cleaning System).

Jan 1, 1982

By Joseph Sopko, Xavier Lacourse-Dontigny

For the REM (Réseau Express Métropolitain) project, a 2500 m tunnel was built using a tunnel boring machine (TBM) under the Montreal Pierre Elliott Trudeau Airport (ADM). Although the geology under the Montreal Airport (ADM) would have been suitable for an excavation with a hard rock machine, the rst section reuired an earth pressure balance (EPB) TBM due to the soft soil located under wetlands. After excavating 280 m, the TBM was blocked in a transition zone of unconsolidated, water-bearing soils directly above the underlying bedrock. A free air intervention was not possible due to these geological conditions. After several failed attempts to create a slurry cake for hyperbaric interventions, a ground freezing system was designed and implemented, incorporating angled pipes drilled from outside the wetlands to directly in front of the cutterhead. This paper discusses the engineering reuired to form a frozen, water-tight zone in front of the cutterhead using liuid nitrogen. It also describes the complex method of replacing the disc cutters while holding the ground freezing system active in a manner protecting the health and safety of the workers.

Jun 23, 2024

By A. G. Ulsoy

In recent years there has been an Increasing Interest In the application of automatic control theory to mineral processing systems, and numerous applications of mineral process control have appeared in the literature. A general approach to the synthesis of mineral process control systems is presented. The first phase of the control system design consists of specifying the control objectives, process variables and their interactions; these topics will be discussed with specific reference to mineral processing. The second phase Is con¬cerned with selection of control strategies algorithms, instrumenta¬tion, and other components of the control system and is discussed at length. These concepts are then illustrated by a flotation control case study.

Jan 1, 1981

By William Gleason

The mining industry is a unique space. It is one in which geologists and chemists can intersect with computer and data science professionals daily. The industry requires expertise in not just mining and metallurgical engineering, but also electrical, mechanical, environmental and more. It requires expertise in worker health and safety, behavioral science, finance and economics, as well as human resources management. The locations of mining operations are often in remote corners, and for underground activities, they are unlike anything else in the world. The industry presents those who join it a wealth of opportunities, but often struggles to overcome incorrect perceptions of safety, labor and environmental standards, making it difficult to recruit and retain employees at a time of increased demand for mined materials.

Dec 1, 2025

By Marshall D. Himes

The Pima mine, 39,000 ton per day copper mine, is located 17 miles south of Tucson, Arizona. The mine is in a sequence of Paelozoic and Mesozoic sediments striking east-northeast and dipping southeasterly intruded by a Tertiary quartz monzonite porphyry. The Paleozoic Permian(?) dolo¬mites, limestones, and sandstones have been altered to talc-silicate skarn, marble and quartzite. The overlying Mesozoic Triassic(?) clastic sediments have undergone some recrystallization and hydro¬thermal alteration. The clastic metasediments are divided into three distinct lithologic units, lithic arenite, arkose, and inter¬bedded and overlying black argillite. Three types of hydrothermal alteration in the clastic rocks are propylitic alteration (epidote, chlorite and quartz, with or without sericite), quartz-sericite alteration, and potassic alteration (K-feldspar and quartz, with or without sericite and chlorite). The porphyry has undergone potassic alteration. Dominant structures are an east-west post mineral fault in the western part of the pit, and strong low angle faulting and shearing which truncates the ore body at depth. Two joint sets, one parallel to bedding and the other at right angles to bedding are prominent in the mine. Faulting is in two dominant directions, one striking northwest, dipping northeast and the other striking northeast, dipping northwest. Mineralization is predominantly disseminated pyrite and chalcopyrite, and molybdenite-quartz veinlets. There are lens important amounts of magnetite, hematite, sphalerite, galena, tennantite and bornite. Mineralization is believed to be both structurally and chemically controlled.

Jan 1, 1972

By W. C. Baver

Even before the energy crisis developed in the early '70's, considerable research world-wide was being directed towards the development of schemes to both reduce the energy requirements and to reduce air pollution emissions associated with the manufacture of glass. In many cases the sought-for solutions would benefit both objectives. If, for example, the glass batch could be consolidated into such compact forms as briquettes or pellets, they could be preheated in a moving-bed heat exchanger with the high-temperature exhaust gases from the glass furnace. Lower furnace temperatures would thus be possible with a corresponding reduction in heat losses and total fuel consumption. Moreover, the lower temperatures would also reduce the amount of nitrogen oxides generated in the furnace and emitted to the atmosphere. Many tests on consolidated glass batch have been run in many countries. In some cases, extended tests on production furnaces have also been included in the programs. For various reasons, however, none of these has proved to be economically attractive. The current, but temporary lull in the rapidly rising cost of energy which has been with us in recent years, has reduced the push for research for energy saving means for melting glass. A few of the current programs will be discussed. Since raw material requirements, primarily physical in nature, are affected by some of these schemes, these will also be considered.

Jan 1, 1986

By C. A. Oestreicher

For sulfide minerals, the presence of dissolved oxygen in the water phase is an influencing factor for separation by flotation. Klassen and Mokrousov(I:217l distinguish three stages of oxygen adsorption; namely, reversible adsorption, activated adsorption and, finally, surface oxidation. While contraversial, limited adsorption of oxygen is believed to improve the interfacial reactivity between collector and mineral. Intensive surface oxidation of sulfide minerals usually results in unsatisfactory flotation with collectors of the xanthate type. The influence of dissolved oxygen in the water phase has received consideration for sphalerite, galena, chalcopyrite, arsenopyrite, chalcocite, and covellite(2,3,4,5,6). However, the nature of surface oxidation products of sulfide minerals has received very limited investigation(6,7). Lightly oxidized galena promotes the adsorptive reaction of surfactant (xanthate or dixanthogen). Tolun and Kitchener(8) state that limited interaction occurs between galena and xanthate under relatively reducing conditions. And, that exposure to oxygen raises the electrochemical potential of the galena to that required for reaction with xanthate or dixanthogen. In the latter condition, the galena has an "effective flotation surface". On the other hand, intensive oxidation of galena reduces the chemical reaction with xanthate collectors (9) . Complete flotation with xanthate-type surfactants with increasing oxygen content in the water phase has been determined to have the following sulfide mineral sequence(3): galena, pyrite, sphalerite, chalcopyrite, pyrrhotite and arseno-pyrite. The work of Cusack(4) suggests that some threshold amount of oxygen is necessary for flotation to occur, but heavy oxidation hinders flotation with xanthates. According to Tolun and Kitchener(8) catalytic oxidation of xanthate to dixanthogen occurs. From infrared studies, Poling and Leja(IO,II) found that in the absence of oxygen in solution, xanthate ions do not adsorb either on

Jan 1, 1972

By John Newby, Mahmood Khwaja, Bernard Theron, Janice McGovern, Bernard Catalano, Michael S. Schultz

Launching a full-size pressurized-face Tunnel Boring Machine (TBM) in difficult ground conditions is always challenging. Recently, few projects have innovated the process by scaling the trenchless method of pipe jacking, and modified steel bell approach, to facilitate the launching of a full-size TBM without the need for large and deep trenches, starter/tail tunnels, or for incrementally installing supporting gear as the machine advances. This paper presents three such projects; evaluates the post-bid contractor proposed modifications; details the innovative use of pre-cast pipe segments to facilitate machine launch; and, provides an overall assessment of the benefits, challenges and lessons learned related to the modified approach.

Jun 13, 2021