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By T. Gupta, T. Ghosh

Rare earth elements (REEs) and their compounds are essential in a multitude of mundane and sophisticated applications such as renewable energy technologies, catalysts, medicine, and defense applications. The global supply deficit could be attributed to the destabilization of REE market that has, as a result, incentivized indigenous production of REEs. Cost-effective and environmentally benign opportunities are being explored for the production of REEs from non-conventional mineral sources including coal and coal by-products to stabilize the supply chain. Coal from Healy coal mine and Wishbone Hill deposits in Alaska have been quantified for REEs and were found to possess elevated total REE concentrations as compared to world average levels (60– 70 ppm). The objective of the study was to concentrate the REEs in the froth phase by froth-flotation of the fine size fraction (< 75 μm). A Box-Behnken design of experiment was employed to ascertain the main and interaction effects of operational parameters on response variable by analyzing 3D response surfaces. Experiments were carried out to maximize REE recovery and concentration by modeling and optimization of three operating variables (frother dosage, pulp density (% solids), and collector dosage). Based on the results, the optimum flotation conditions for maximum recovery at an elevated concentration of REEs in the froth fraction was obtained at 4.2% solids and 32.7 ppm of frother dosage for Healy sample and 10% solids and 37.9 ppm of frother dosage for Wishbone Hill coal sample. The quadratic relationship between the input and response variable was found to be independent of collector dosage suggesting good surface hydrophobicity and floatability of the two coal samples.

By Steve Rogers

Nautilus Minerals was listed on the Toronto Stock Exchange in May 2006. The company now has major mining companies Anglo America (5.7%), Teck Cominco (7.2%) and Epion Holdings (22.4%) as significant shareholders, and has raised approximately $US346 million dollars to develop the world&apos;s first deep-water mine. The company is currently targeting high-grade copper and gold in seafloor massive sulphide mineralization, located near plate boundaries in back-arch basins of the Western Pacific. The first mine scheduled to be developed by the company is located in 1,600 meters of water at Solwara 1, in the relatively quite waters of the Bismarck Sea approximately 50 km from the port of Rabaul, within the Territorial Waters of Papua New Guinea. During 2006 and 2007 the company completed detailed environmental and geological studies, culminating in a number of world firsts, including the world?s first NI 43-101 compliant resource statement and environmental impact study for a seafloor massive sulphide system. Permitting is well advanced for the project, with initial production scheduled for late 2010, subject to timely grant of the permits. Extensive government and stakeholder liaison and engagement has been undertaken throughout the projects life, and is a core feature of Nautilus&apos; desire to "do it right" in all aspects of this new industry.

Jan 1, 2008

By B. A. Hancock

New permit discharge standards instituted at Hecla Limited?s Lucky Friday Mine required installation of water treatment plants to manage water quality at two outfalls to the South Fork of the Coeur d?Alene River. The 002 Outfall Water Treatment Plant (WTP) is a clarification-filtration plant for treating the combined mill and underground discharge water flows. Process optimization efforts were a significant challenge until the negative impact the exploration diamond drilling products had on the clarification process was identified and resolved. The products were being wasted directly to the mine water discharge system which was pumped to the surface WTP. Anionic soluble oil and polyacrylamide based products were causing TSS particle hydrophobicity and dispersion that greatly affected coagulation and flocculation response, resulting in excessive chemical usage and treatment control issues. This paper details how problems associated with the drill products negatively impacted the 002 WTP and how system changes, alternative product usage and treatment at the source resulted in more consistent plant performance.

Jan 1, 2011

By J. W. Hawkins, K. B. C. Brady, K. Miller, J. Cuddeback

Remining of abandoned coal mines in Pennsylvania requires the implementation of pollution abatement and mining techniques called Best Management Practices (BMPs). Water-quality data from over 100 remining sites with more than 230 abandoned discharges were analyzed with respect to the types of BMPs employed to abate the pollution loadings of acidity, iron, manganese, aluminum and sulfate. Discharges exhibiting a significant decrease in acidity were most highly associated with sites where large volumes of alkaline materials were encountered (66.7%) or added (63.7%). The best results for iron loading were achieved with large-quantity alkaline addition (54.6%) and water handling systems (47.8%). Water handling systems (47.4%), daylighting (40.7%), and revegetation (40.2%) were associated with significantly lower manganese loadings. The decreases in acidity and sulfate loads associated with increasing the amount of alkaline material in the backfill indicates that the production of acid mine drainage can be retarded by adding large quantities of alkaline materials.

Jan 1, 2002

By G. H. Kuhnhausen

The Bear Creek Uranium Mill was designed in 1975 to process 909 tonnes per day (1000 STPD) of low-grade uranium ore from the Powder River Basin in Wyoming. The mill was expanded to 1818 tonnes per day (2000 STPD) in 1979. The Bear Creek Uranium Project is owned by the Bear Creek Uranium Company, a partnership of Rocky Mountain Energy Company and Mono Power Company. The original mill design contemplated processing ores from Bear Creek Uranium Company properties exclusively. The expanded capacity has been utilized for tolling ores from Kerr McGee Nuclear Corp. and other mining companies in the region. This paper describes the process of designing the original mill, the lessons learned from operation, and the design of the process modifications required for expansion. The project background, design philosophy, design basis, design criteria, actual flowsheet, special design considerations, and a comparison of assumed operating conditions and actual operating results will be presented. Bear Creek Uranium Company wishes to thank and acknowledge the help granted by the many operating companies who provided invaluable information, insight, and critique of the Bear Creek design through all the various stages and were instrumental in the successful completion and start-up of the mill. Without their contributions, the design philosophy used at Bear Creek would not have been possible and the results obtained would surely have been less satisfactory.

Jan 1, 1979

By Roger K. McLimans, Venkatramaiah N. Vasudev, Christian Knudsen, Stefan Bernstein, Dirk Frei

Computer Controlled Scanning Electron Microscopy (CCSEM) analyses of sediment samples from coastal regions of Kerala and Tamil Nadu states and the heavy mineral deposits of Chavara, South India, show large lateral differences in the titanium content in ilmenite due to varying degrees of iron leaching. As the depositional environments for the sands with varying degrees of ilmenite alteration are comparable, the cause for the different degree of alteration is due to differences in the primary source of the ilmenite or to differences in the geochemical history of the ilmenite grains during transport from source to deposit. The CCSEM analyses of the heavy mineral fractions show that source of sediments with a high content of titanium-enriched ilmenites, mainly the heavy mineral deposit around Chavara, resides in the khondalite belt of South India (granulite facies metasediments). The less titanium-enriched ilmenites are sourced from other rocks in the area such as the charnokites. Those conclusions are based on the high MgO content in the leached ilmenites, chemical composition of the accompanying garnets (low CaO and high MgO), and the concentration of aluminum-rich minerals in the sands.

Jan 1, 2005

By Keith Whitworth

The USSR, over the last 20 years, has continued to increase its out-put year by year and it is now almost four times what it was at the end of the Second World War. In 1975, it exceeded 700 million tons of run-oi-mine coal (all ranks) which amounts to over 20 percent of world output. This rapid progress has been due to modernization of the industry, by means of increased mechanization and automation and the development of new machines and systems for underground workings and by the expansion of open-pit workings and the development and implementation of larger earthmoving machines.

Jan 1, 1977

By M. C. Radomsky

Approximately sixty, small, surface coal mines in Pennsylvania participated in a program designed to improve safety performance in the workplace. The method involved the use of safety sampling and observation to assess the safe standards of worker behavior and work conditions. Data were collected through the use of operation-specific, on-site safety records covering seven major occupational units. Workplace events observed (acts and conditions) were assigned a hazard classification; feedback, both immediate and delayed was initiated to improve safety performance. The experiences drawn from this pilot project have proven the need to continue to pursue this behavioral approach; however, a stricter methodology needs to be adopted in the collection and analysis of data.

Jan 1, 1987

By Stephen M. Smading

The Jinping-II hydroelectric project in China features four parallel headrace tunnels approximately 18-km- (11-mile-) long. Two will be excavated by tunnel boring machines (TBM) and two by drill-and-blast. A nearby fifth tunnel is being excavated by a 7.2-m (23.6-ft) TBM to draw down ground water in advance of excavating the headrace tunnels. Unique onsite assembly of a 12.43-m (40.7-ft) main beam TBM and backup system was completed on Sept. 18, 2008 in the remote mountains of the Sichuan province. The equipment was assembled onsite, without previously having been assembled and tested in a factory, using a method called onsite first time assembly (OFTA). This paper addresses the following topics: ? Project description including geology and terrain. ? The decision process leading to onsite, first time assembly, the assembly process and logistics, and lessons learned. ? Design features of the TBM and backup system. ? Operational history from startup to the writing of this article.

Jan 1, 2009

By Ronald D. Mariani, Gregory E. Mahoski

BACKGROUND The steel and iron ore industry has had a long history of an adversarial relationship with its union and workforce. The Empire Mine during its first 40 years of existence was no exception. The "we-they" mentality went hand-in-hand with the normal by-product of an adversarial relationship, grievances and arbitration. This relationship was considered the norm and it was not until the late 1970s that consideration was given to changing this relationship. At this time the industry was involved in a fight for existence and the economic pressure demanded increasing productivity to lower cost. The challenge to survive highlighted the fact that an adversarial relationship was not conducive to attaining the needed gains in productivity. The first formal attempt to change the way we worked came in the 1980 Labor Agreement which provided for the opportunity to utilize Labor Management Participation Teams (LMPTs). LMPTs were established at the Empire Mine and they functioned for a couple of years. The teams spent most of their time working on creature-comfort issues and steered clear of dealing with productivity issues. Mine shutdowns had occurred in Michigan resulting in large layoffs, and the union was trying to add jobs and was not supporting teams that could increase productivity and eliminate jobs. When the 1986 labor negotiations began, the local union pulled their support of the LMPT process. Other initiatives were negotiated over the years to foster a change in the culture but, as with the LMPT program, they did not produce the desired culture change. It became abundantly clear: you cannot negotiate a culture change.

Jan 1, 2004

By H. Wesley Peirce

Arizona, in 1966, has continued to be the site of an extensive and intensive search for metallic mineral deposits. Over fifty separate entities--companies and individuals--have been actively engaged in mineral exploration programs, both large and small, in the Basin-and-Range portion of the State. Certainly, copper has been primarily responsible for the major efforts, although associated gold, silver, and molybdenum mineralization also has been important in the economic evaluation of potential copper deposits. It is not difficult to explain why the Basin-Range portion of Arizona is receiving such attention. Part of the story, undoubtedly familiar to most, can be illustrated by reference to three graphical presentations. For example, Figure 1 shows Arizona&apos;s annual copper production for the period 1955-1965, inclusive, and it demonstrates that new records of production have been accomplished in each of the past 6 years and in 9 of the last 11 years.

Jan 1, 1967

By E. S. Bianchin

The more complex control needs of today&apos;s mineral processing plants combined with ever-changing digital technology have brought numerous improvements to process control systems. This paper discusses recent advancements in distributed control systems (DCS) which facilitate the implementation of process plant automation. Some of the topics of discussion include integrated function controllers, weigh scale and analyzer interfacing, operator interfacing, personal computers, process information management and process plant management.

Jan 1, 1988

By Dennis Molvik, Roberto J. Guardia, Brad Cowles, Rick Andrews, Robert A. Robinson

A 220-meter (m) segment of the Henderson/ ML King Combined Sewer Overflow(CSO) consists of two 1.8-meter-inside diameter (I.D.) pipe-jacked tunnels that pass beneath Interstate-5 and the BNSF and UPRR railroads. A seismic tomography survey was conducted to develop a 3-dimensional profile of the tunnel zone and better define potential obstructions. The tomography was conducted through three 11 cm high-density polyethylene (HDPE) pipes installed in a triangular pattern around the future tunnel alignments using horizontal directional drilling methods. The pipe-jacked tunnels have been successfully completed, thus permitting a comparison between the predicted obstructions and those actually encountered. The top HDPE tomography pipe was also used to monitor settlements with an experimental horizontal profiler above the advancing tunnels during construction and located two areas of ground loss beneath I-5 that were subsequently grouted.

Jan 1, 2005

By W. G. Lawrence

The rapid development of science and technology in Russia has been the result of well laid plans since 1918. At that time the Institute of Silicates was established is Moscow and later the establishment of similar more specialized institutes for the study of cement, glass, refractories, construction ceramics, electrical ceramics, building materials and asbestos provided the necessary research facilities for studies related to all types of ceramic inorganic materials. The&apos; Institute of Ceramics and the Institute of Silicate Chemistry, Academy of Sciences, USSR, were founded in Leningrad. The work now going on in these various research&apos; institutes covers every branch of silicate science and ceramics The impetus behind such establishment of special¬ized laboratories is no doubt due to the 5-year plans and the necessity of improving the scientific knowledge regarding the materials being used and the products being manufactured.

Jan 1, 1960

By S. S. Peng

High horizontal stress has been well recognized as a significant factor in roof control. It can adversely affect roof stability if the panel is designed improperly. Mining experience has shown that it can cause a cutter roof. The effects of high horizontal stress on roof stability depend on many factors such as magnitude and direction of the maximum principal horizontal stress, ratio of the maximum to minimum principal horizontal stress, structure and mechanical properties of the immediate roof and mining sequence. However, little is known about the intrinsic mechanism of high horizontal stress effect on roof stability except some conceptual explanations. In order to design a stable entry, the redistribution and concentration of high horizontal stress around the openings must be fully understood. Using the 3-D finite element analysis technique, this paper presents the redistribution and concentration of high horizontal stress field for a three-entry system with different orientations of horizontal stress. Based on the horizontal stress redistribution, possible roof failure for different orientations of horizontal stress is analyzed.

Jan 1, 1996

By Jed Greenwood, Lyall Workman, Michael Haggerty, Russell Sheets

Draglines often work from a position on the active highwall or spoil side bench to remove undisturbed waste material and spoil in the previously mined pit. To protect the dragline crew members and the machine, it is necessary that the highwall remain stable while the dragline is present on the bench. In the past several years, we have been involved in determining the causes for highwall failures that included the dragline. While there have been no injuries and limited dragline damage with these incidents, the potential certainly exists for a more serious outcome. In all cases, the operation had completed a geotechnical study to support the ground control plan and pit designs. However, all these incidents included aspects that would not likely have been identified in studies to determine highwall and spoil designs to support ground control procedures. In general, these events included aspects that were localized and would have been difficult to identify in initial slope stability studies either observationally or during the soil testing and modelling efforts. Although the authors do not have quantitative evidence of this, it does seem there has been an increased number of events in recent years. This may be due to loss of institutional knowledge, mining in more challenging areas, or simply an increase in localized variation. This paper will describe some of the issues we have seen and what the causes of failure were. It becomes clear that avoiding similar incidents in the future requires on-going observation and inspection of active highwalls and spoil benches to try and identify local variability and impact on mining. The information can proactively be used to update stability modeling of any concerning issues to determine likelihood of problems and to develop solutions.

Feb 1, 2025

By Hossein Kazemi

This article is a review of fluid flow and mass transport in fractured rocks. The topics include: single-phase and multiple- phase flow theory, formation productivity or injectivity improvement by artificial fracturing, and mass transport associated with fracture acidizing. Possible extension and application of such ideas to in situ mining in fractured rocks are presented.

Jan 1, 1974

By Robert J. Timko, Edward D. Thimons, Robert L. Derick

In early June, 1986, a fire of unknown origin erupted in one of several main entries of a coal mine located in southwestern Colorado. The fire was aggressively fought with high- expansion foam. As a result of several strategic decisions, the fire appeared to be held in check. Unfortunately, sufficient quantities of foam were unavailable and as soon as the foam was depleted, control of the fire was lost. To prevent further damage and the possibility of an explosion, all entries to the mine were sealed. This paper recounts activities from the discovery of the fire to the initial reentry of the sealed mine including location of the fire, the decisions made to best combat it, and the steps taken to rapidly and securely seal the mine when this became necessary. The mine operator requested the Bureau&apos;s assistance in obtaining and analyzing mine fire gases taken from sampling ports placed through the mine seals. This report describes how samples were taken and what gases were analyzed. In addition, this work describes the initial exploration of the sealed mine by personnel using oxygen breathing apparatus.

Jan 1, 1987

By D. Brunner

System simulation is an increasingly popular technique for analyzing and improving existing as well as newly designed underground mining operations. An engineering firm that specializes in simulation helped a major metals producer build a long-range planning model of an existing underground mine. Subsequently the team adapted this model to assess technology alternatives in the design of a new mine. The two models differ in the level of detail used for modeling the development process. This paper discusses the differences in approach between the models along with the experiences gained and challenges faced during the construction and use of the models.

Jan 1, 1999

By M. Radwan, S. Shimada, S. Z. El-Tawil, K. A. El-Barawy, Y. Miyamoto

This study presents the results of synthesizing monolithic siliconoxynitride, Si2N2O, ceramic from a mixture composed of reclaimed silicon and natural desert sand by using the nitriding combustion synthesis method. Single-phase Si2N2O powder was prepared by the combustion of a mixture composed of silicon and pulverized sand in 3 MPa nitrogen gas. The combustion reaction completed in 2 min and the combustion temperature reached 1577°C.The as-synthesized Si2N2O powder is agglomerate of fine particles with sizes < 5 µm and has various morphologies; rod-like and irregular crystals, irregular kinking, hollow crystals and grown pseudo-hexagonal prismatic crystals. Porous Si2N2O compacts (24.5–47.1% porosities) were fabricated from the synthesized Si2N2O powder at different calcia-alumina additives (5–20 wt%) by normal sintering at 1500°C for 1 hr in N2atmosphere.They showed superior oxidation-resistance at high temperatures up to 1500°C in an oxidizing atmosphere of Ar/O2/H2O(70/20/10 kPa).Near-full dense Si2N2O compacts were also successfully fabricated from the synthesized Si2N2O powder with 5 wt% oxide additives by using the spark plasma sintering at 1600°C.DenseSi2N2O had good mechanical properties (18.7 GPa Vickers hardness, 3.3 MPa.m1/2fracture toughness and 363 MPa strength) and excellent chemical and oxidation resistance.

Jan 1, 2004