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By B. H. Kim

The use of a 25.4 mm diameter water-only hydrocyclone for separating fine-size (-150 µm), high-density (>4.5 g/cc) particles from similar-size, lower-density (2.65 glee) particles was investigated. It was found that a single-stage separation recovered nearly 90% of the heavy minerals (7.0 g/cc), while achieving a volume reduction of about 70%. The use of dense medium in a single stage improved volume reductions to 90% at similar heavy mineral recoveries. In addition, computer simulations of a three-stage circuit were performed, which showed that recoveries approaching 97% with volume reductions of 95% were possible.

Jan 1, 1998

By John Rajala

The Otjikoto Gold Mine in the Republic of Namibia is located approximately 300 kilometers north of the capital city of Windhoek. The project features surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and recovery of gold. Initial mill design capacity was 2.5 million tonne per annum but then expanded after 9 months of operation to 3.1 million tonne per annum. The technical steps to establish the Otjikoto mill design from process selection in the due diligence stage, through flowsheet development in the feasibility study followed by detailed engineering design are reviewed in this paper along with mill performance during start-up and in 2019.

Oct 30, 2020

By M. L. Free

Several studies of the fluorite/oleate flotation system have shown that under certain conditions calcium dioleate is formed at or transported to the fluorite surface. Adsorption of significant amounts of calcium dioleate is generally observed above oleate concentrations of -6 -5 between 4 x 10 and 4 x 10 M, yet little explanation of the onset of calcium dioleate adsorption is provided. In this study in-situ and ex-situ FTIR/IRS experiments have been performed in connection with thermodynamic solution phase analysis to better understand oleate adsorption as well as the onset of calcium dioleate formation. Results from this study are analyzed and compared to industrial practice.

Jan 1, 1995

By T. D. Wheelock

The effect of various flotation depressants and surface treatments on the floatability of coal derived pyrites in the presence of XIBC was investigated with a modified Hallimond tube microflotation cell. The floatability of pyrite particles which had been cleaned with hot dilute (5%) hydrochloric acid was relatively large. However, the floatability of such particles was reduced greatly by the addition of specific depressants such as calcium hydroxide and also by treating the pyrite with an aerated warm alkaline solution. Although this treatment and these depressants also had some effect on the floatability of coal particles, the effect was much less than on the pyrite particles.

Jan 1, 1979

By D. C. Fuller

CoaLiquid, Inc. (CLI) has been in the coal- oil-mixture (COM) business for over five (5) years. The initial pilot processing facility was replaced by a 2000 barrel per day commercial production facility in August of 1979. For over two (2) years CLI has been expanding its efforts and conducting large scale production and combustion demonstrations successfully in many locations across the United States. To facilitate the marketing effort, CLI has recently constructed a special trailer containing all equipment needed for a temporary COM retrofit. CoaLiquid has conducted commercial scale combustion demonstrations in the following types of combustion units: kilns, calciners, industrial boilers, blast furnaces and driers.

Jan 1, 1982

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By Dipl. -Ing. H. -J. Sager

The ‘Westerschelde Tunnel’ underpasses the estuary of the Schelde in the Netherlands. The tunnel will consist of two tubes which are driven by two hydroshields (slurry shields). The tunnels will each have a length of approx. 6.6km and a bore-diameter of 11.33 m. Demanding ground conditions had to be considered during the design of the shield machines. Loose sands, extensive clay formations and high ground water pressures of up to 6.5 bar will be encountered during the tunnel drive. The tunnelling activities will start in the middle of 1999 and are scheduled to end by the end of 2001.

Jan 1, 1999

By S. L. de Moraes

This study aimed to identify a way to reduce the use of bentonite in the pelletization of magnetite. With this goal, different combinations of binders were compared to bentonite by examining the quality of pellets obtained by balling drum agglomeration. Pellets were subjected to routine tests that included simple compression of the wet and dry 105°C pellets, dropping wet pellets to determine their ability to survive handling and submitting pellets to thermal shock to determine how they tolerate drying and preheating. The best results use sodium silicate (1.5%) as a binder and show that it is possible to pelletize iron ore without using bentonite.

Jan 1, 2010

By Elisa Comis, David Chastka, Miriam Piemontese, Maria Chastka

The Lower Olentangy Tunnel (LOT) Project involves the construction of a 17,000 ft (5,200 m) long, 12 ft (3.65 m) internal diameter Combined Sewer Overflow (CSO) tunnel. The tunnel is excavated by using an Earth Pressure Balance (EPB) machine designed to cope with soft ground, weak rocks and water pressure. The project is located in the city of Columbus, Ohio and the main geotechnical hazards are related to the heterogenous soils and the low overburden in an urban environment. This paper focuses on the performance of the EPB first drive and the comparison between the design assumptions and the actual TBM performance during construction.

Jun 23, 2024

By D. Bahrami, G. Danko

Spatial and temporal temperature and humidity variations for 5000 years are simulated in an emplacement airway within the conceptual, high-level nuclear waste repository proposed to be built at Yucca Mountain, Nevada. A multi-scale model is configured using MULTIFLUX, a thermohydrologic-ventilation code. The predicted surface temperature of most waste packages during post-closure exceed 140oC, the threshold limit known for likely localized corrosion for Alloy 22 waste package material. Small amounts of infiltration airflow through the mountain in Panel 5 are found to transport liquid water condensate to some of the waste packages emplaced along the peripheral section of the drift due to edge cooling.

Jan 1, 2004

By J. V. Thompson

The Powderhorn complex as a source of perovskite (calcium titanate) containing about 1.5% rare earths has been examined in several recent feasibility studies. Much promising exploration and process research has been done in recent years. This paper is presented with cautious optimism and with the acknowledgment that there may be some technical and economic areas yet to be explored. The Powderhorn carbonatite and alkalic stock in Gunnison County, Colorado, lies about 203 airlines km southwest of Denver at an elevation of 2450 to 2750 m (see Figures land 2). All of the mineable ore bodies are owned by Buttes Resources Company of Houston, Texas.

Jan 1, 1990

By W. J. Nosek

Reserve Mining Company completed construction on a major process modification project in June of 1980. These modifications enabled Reserve to reduce and control its final iron ore pellet silica content from 9.0 20.77 percent to 5.0 50.26 percent. The paper outlines the implementation of neutron activation on-line analysis and associated computer control loops for measuring and closely controlling the silica content of the iron ore concentrate at Reserve Mining Company. It contains a general overview of Reserve's taconite processing facilities and a presentation of the theory and operation of the neutron activation analysis equipment coupled with the computer silica control loops.

Jan 1, 1983

By Anastasia Xenaki, Edmundo Laporte, Antonio Nieto, Jesus Castillo Gomez, Oscar Velasquez

It is particularly challenging for the mining industry to create and implement an efficient and adaptable mining innovation model to secure the continuous improvement of processes and products via technology. Human resource departments must play a vital role in shifting the mining culture, enabling these new classes of digitally skilled professionals to manage the mining operations of the future. This paper proposes the implementation of a concept based on the 5S mining innovation model ((a) Nieto, 2019), in a coal mining project in Central Asia, Mongolia. Practical and empirical evidence suggests that the model could serve as a roadmap to developing technologies and methods for the mines of the future.

Feb 1, 2023

By S. K. Nicol

The results of column flotation tests conducted on a bulk sample of ultrafines discarded from the fine coal desliming cyclones at the Riverside coal preparation plant of Theiss Dampier Mitsui Coal Limited are presented. A 9% ash concentrate was obtained from a 51% ash ultrafine feed at 75-80% recovery of combustibles in a single stage of column flotation. From this result it is predicted that installation of column flotation at Riverside would lead to the annual recovery of additional coal worth $US5.1M. The operating conditions for coal and copper column flotation are compared and some differences which may result in a variation in column design are noted.

Jan 1, 1987

By Paul G. Schmidt

The Crandon massive sulfide deposit Forest County, Wisconsin, was discovered by Exxon Minerals Company, U.S.A., in July 1975. Announced estimated in-place reserves are 62 M metric tons (70 million short tons), grading about 5% zinc and 1% copper. The reserves are evenly divided between massive sulfide are and stringer sulfide ore. The sulfide body is associated with Precambrian felsic pyroclastic rocks, and it is overlain by intermediate volcanic rocks and their derived sedimentary rocks. These rocks were subjected to greenschist facies metamorphism and were tilted to a near-vertical attitude. Geologic observations indicate a submarine-volcanic-exhalative origin for this deposit.

Jan 1, 1978

By Jacob Mathis, Mark Bradford, Alston Noronha, R. M. True

In June 2022, Louisville MSD completed a 6.5-km (4.0-mi), 6.1-m (20-ft.) diameter CSO conveyance and storage tunnel system located along the Ohio River in downtown Louisville, Kentucky. For large diameter shaft and tunnel construction, drill-and-blast operations among other methodologies were used in close proximity to federal, commercial, and residential properties with no impact to stakeholder infrastructure. s one of the rst maor tunneling proects in Louisvilles metropolitan area, this paper explores Black & Veatchs rigorous geotechnical instrumentation monitoring program that provided uality assurance for local stakeholders and afrmed innovative tunneling solutions can be successfully executed in an urban setting.

Jun 23, 2024

By M. D. Johnson

The San Andres mine, located in the western mountain region of Honduras, Central America, contains epithermal gold mineralization as disseminations, in quartz-chalcedonic veins and stockworks. Host rocks include a thick sequence of Cretaceous to Tertiary conglomerates, sandstones, rhyodacite tuffs and andesites. Mineralization is controlled by northwest and northeast striking, normal faults and fractures which dip steeply east and west. Currently, 500 STPD of 1. 93 Grams/MT gold ore is being open-pit mined from the conglomerate and andesite. The mine is at the west end of a mineralized zone that can be traced over an area of approximately 1.5 square kilometers.

Jan 1, 1993

By Francis X. McCullough

After OSHA published a Notice of Proposed Rulemaking on August 5, 1983, to revise its standards for Underground Construction, many contractors and their representative associations became concerned by the sweeping changes in the proposed rule. After reviewing all of the evidence and testimony on file with OSHA, the contractors presented extensive written and oral testimony to the Department of Labor in Washington, D. C. to help insure that the final published rule would be effective without jeopardizing the economic viability of the industry. The results of those efforts, the entire OSHA rulemaking process, and the opportunity for the construction industry to participate in that process will be discussed.

Jan 1, 1985

The Australian states of New South Wales (NSW) and Queensland, because of their endowment of black coal resources, dominate the production and export statistics for Australian coal. NSW produced 86 million tonnes of saleable coal in 1994, representing a doubling of output since 1980, or a growth of 5% per annum. Asian demand for thermal and coking coal has, of course, driven this growth in NSW. This high Asian demand is forecast to continue and NSW will seek to secure its share. This paper focuses on some of the issues facing NSW in the future, and in particular, examines some of the major new and proposed mining projects.

Jan 1, 1997

The surface of chalcopyrite was studied in situ in aqueous solution by an atomic force microscopy (AFM). The AFM images showed that some absorbate in patches was detected on the mineral surface, after the chalcopyrite sample was soaked in 5x10-4M potassium ethyl xanthate (KEX) solution at pH 11 for 10 minutes. These patches increased in size with time elapsing. At the same time, as shown by the obtained AFM force curves, the adhesion between the AFM tip and the substrate increased greatly due to the adsorption. Rinsing with ethanol removed the absorbate from the chalcopyrite surface, as well as the big adhesion observed in KEX solution.

Jan 1, 2010