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By F. F. Roberto

Many techniques that are used to characterize and monitor microbial populations associated with sulfide mineral bioleaching require the cultivation of the organisms on solid or liquid media. Chemolithotrophic species, such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, or thermophilic chemolithotrophs, such as Acidianus brierleyi and Sulfolobus solfataricus can grow quite slowly, requiring weeks to complete efforts to identify and quantify these microbes associated with bioleach samples. Real-time PCR (polymerase chain reaction) assays in which DNA targets are amplified in the presence of fluorescent oligonucleotide primers, allowing the monitoring and quantification of the amplification reactions as they progress, provide a means of rapidly detecting the presence of microbial species of interest, and their relative abundance in a sample. This presentation will describe the design and use of such assays to monitor acidophilic microbes in the environment and in bioleaching operations. These assays provide results within 2-3 hours, and can detect less than 100 individual microbial cells.

Jan 1, 2009

By D. Dimitriadis, T. Polglase, W. Phillips, R. Jenny, M. Botz

Cyanidation processes for the extraction of gold or silver frequently involve the processing of sulfur-containing solids which react with cyanide to form thiocyanate. The formation of thiocyanate is an undesired side-reaction, and in many cases thiocyanate formation results in a prohibitively high cyanide consumption. With the increasing number of gold and silver mining projects which involve the processing of sulfide ores or concentrates or which utilize a biological sulfur oxidation process, more attention has been focused on minimizing thiocyanate formation and in treating solutions to eliminate toxicity associated with thiocyanate. Though not yet commercially applied, there are several technologies available to recover cyanide from thiocyanate to both reduce tailings toxicity and allow the reuse of cyanide otherwise lost to thiocyanate formation. This paper presents an overview of technologies available for recovering cyanide from thiocyanate along with estimated operating costs for the technologies. Pilot testing data suggests that in some cases, cyanide can be recovered from thiocyanate for approximately the same cost as newly purchased cyanide.

Jan 1, 2000

By L. "Andy" Anderson, Stephen N. Short, James E. Friant

Since the introduction of "boxhole" drilling in South Africa in 1973, the concept of a blind raise, drilled upward from below, has become an accepted mining practice. A combination machine, capable of constructing raises to a mining level below, or blind raising upward from a single setup position adds a further dimension in versatility. A machine with these dual operating modes was designated by The Robbins Company as the 53R and was introduced into the Western Deep Level Mines, South Africa in 1984. The unit is powerful (200 hp) and compact (18,000 lbs., in a 10 ft x 4 ft 5 inch x 4 ft 6 inch package). This paper describes the design considerations for the new machine, provides field data from early trials, and looks briefly at its overall market and potential.

Jan 1, 1985

By Huaiyang Zhou

"Hydrothermal systems are a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth’s crust and oceans, and a locus for prolific biological activity on the seafloor and underlying crust. On the other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes.Ultraslow spreading ridges, including the Southwest Indian Ridge and the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys during the last decades, it was suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activity. This increased longevity can be attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004).Distinct from faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree on the Southwest Indian Ridge, is the abundant and pervasive distribution of lower temperature minerals (such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite, etc.) in the hydrothermal fields. Structures formed by lower temperature activity in active and dead hydrothermal fields can also be identified. High temperature minerals such as chalcopyrite are rare or very limited in hydrothermal chimneys at ultraslow spreading ridges. The distribution of diverse low temperature hydrothermal activity is consistence with the deep heating mechanisms and hydrothermal circulations in the complex framework of ultraslow spreading tectonics. On the other hand, deeper and more extensive mineralization at certain locations along the ultraslow spreading ridges can be reasonably presumed."

Sep 1, 2014

By Enrique Hermana, Raymond F. Dalton, Raymond Price, Barry Hoffman

Introduction Chloride leaching of sulfidic ores has been known about for 100 years. It is recognized as a highly efficient process to produce concentrated leach solutions. Despite this, chloride leaching found little practical application until recently because of the highly corrosive nature of concentrated chloride solutions. This situation changed with the advent of modern construction materials such as GRP, polypropylene, butyl rubber, etc. And in the past 20 years, research has burgeoned in the area of chloride hydrometallurgy. The research impetus stemmed from the belief that chloride leaching can provide an alternative to smelters for treating conventional copper concentrates. In addition, chloride leaching was thought to be suitable for on-site refining of copper at small tonnage operations located in remote areas. And chloride leaching was seen as a logical choice for treating unusual or complex concentrates that smelters could not handle. Underpinning these beliefs is the attraction of chloride-based hydrometallurgical processes for sulfidic ores. Sulfur is liberated in the environmentally acceptable elemental form rather than as sulfur dioxide. Consequently, sulfidic copper ores have received much attention. A review of Edmiston in 1984 describes 12 chloride-based processes. All managed to progress past the "laboratory beaker" stage of evaluation. In nine of these processes, copper is recovered electrolytically. Key features of these processes are summarized in Table 1. Table 1 shows that the processes must include a copper solvent-extraction step. Only these processes produce a clean copper electrolyte capable, with no further refining, of directly producing high quality cathode copper. The ICI/Elkem process is the exception here. The rest of these processes use o-hydroxyaryloxime reagents for the solvent extraction of copper and are constrained by the performance of these reagents. This is governed by hydrogen ion concentration (Equation 1). The practical result is that only relatively dilute copper solutions can be treated (Canmet, Phelps Dodge), or careful pH control or adjustment is necessary (Minimet Recherche, B.H.A.S.). This negates one of the attractive features of chloride leaching - its ability to produce very concentrated copper solutions, up to 40-45 gl-1. [ ] In all four processes using o¬hydroxyaryloxime extractants, solvent extraction transfers the copper from the chloride to the sulfate medium. To minimize cross-contamination of the two anions, the loaded organic solvent has to be scrubbed to remove the chloride ion. This represents an additional complication in the solvent extraction circuit. And it

Jan 1, 1988

By Franz Albert Nonnen

Backfill systems have been used for as long as mining activities have existed. Various backfill methods have been developed over the centuries with consideration for geological necessities, the technical means available, security requirements, and available finances. In the past, backfill systems were introduced and upgraded geographically in accordance with local experiences. In modern times, mining engineers participate in international forums for the exchange of knowledge so that backfill techniques and experiences are shared concurrently in mining areas all over the world. Mine backfilling increases the cost of mining so that great attention must be paid to choose a low-cost, reliable, and low maintenance backfill system. Some methods are described in this paper.

Jan 1, 2001

By Libby R. Ricafort, Victorio V. Pato, R. S. Pizarro

Introduction Atlas Consolidated Mining and Development Corp. (ACMDC) started gold production at its Masbate gold mine early in 1980. This involved an open-pit mine and a 3.5-k/d (3850-stpd) carbon-in-pulp processing facility (Pizzaro and Antonio, 1981). When this operation started, the mine began stockpiling sub-grade milling material averaging 1 g/t (0.029 oz per st) gold. Furthermore, geologists estimated that there were additional low grade reserves within the ultimate pit limits. These amounted to 2.4 Mt (2.6 million st) with an average grade of 1.1 g/t (0.03 oz per st) gold. The success of low cost heap leaching prompted an investigation to determine if this tech¬nique would be applicable for the low grade Masbate ore. The findings were favorable and a series of laboratory tests were undertaken. These tests indicated the amenability of this subgrade milling ore to heap leaching. Depending on ore size, gold extractions of more than 60% were obtained. To further define operating parameters for a commercial heap leaching plant, a 400-t (440-st) batch pilot plant was built and operated. These test results were used to design the first commercial heap leaching plant in the Philippines. One design concern was the control of solutions during the rainy season. Due to the material's low grade, every effort was made to minimize capital and operating costs. To this end, surplus mining equipment from the copper operations of ACMDC and used machinery in the crushing circuit were considered. Location: The Masbate gold heap leaching operations are located on the northeastern part of Masbate Island, Philippines. This is about 480 km (300 miles) south-east of Manila. Climate: The climate is moderate with two distinct periods. The dry season runs from January through June, and the rainy season extends from July through December. During the wet season, the rainfall at the mine site averages 300 mm/m (11.8 in. per month) for a total of about 2000 mm/year (78 in. per year). However, heavy downpours in excess of 100 mm/h (4 in. per hour) can occur. Geology: Four distinct rock types have been identified in the pit area. They are tuffaceous agglomerates, andesitic agglomerates, metasedimentary rocks, and hornblende augite andesitic porphyry. The tuffaceous agglomerate occupies the northern and western flanks of the mine. Andesitic agglomerates are localized distinctly in the central portion of the volcanic plug within the mine site. The eastern boundary of the mine is occupied by metasedimentary rocks, whereas, the hornblende augite andesitic porphyry occurs as an intrusive within the andesitic agglomerate and tuffaceous agglomerate. Some areas of the pit contain high proportions of clay minerals, requiring an agglomeration step in the flowsheet. This ensures satisfactory percolation through the heaps. Ore characteristics: Gold and silver are microscopically dis-

Jan 9, 1987

By D. L. Stevens

Following an in-depth scenario and strategic planning exercise in 1997, Noranda’s mine production goal was set at 500,000tonnes per year of both copper and zinc metal within five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in our program but here is what we did first: - Combined the exploration and business development groups - Formed teams to search for and respond to opportunity - Made our geologists more business minded and our engineers more optimistic - Went global - Set clear thresholds, farmed out the marginal properties, fast tracked the others - Focussed reconnaissance exploration where we had a clear competitive advantage - Became a “flexible” partner to both juniors and seniors

Jan 1, 1999

By Jan L. Reichelderfer, Thomas L. Richardson

Completion of the H-3 Highway Tunnel Project was a critical element in opening this award winning project. The exploratory tunnel was completed as a maintenance tunnel and included difficult shafts extending into the main tunnel cross passages. The project also involved a major addition to the traffic operations center including a deep excavation in close proximity to the tunnel portal structures. The projects also included various completions and improvements to the main tunnels, such as paving, drainage, maintenance, and a variety of critical life-safety issues, such as radio systems, telephones, etc. The highway opened in December 1997.

Jan 1, 2001

By D. W. Olson

The estimated value of natural gemstones produced from U.S. deposits during 2004 was $12.9 million. This was a 3-percent increase from that of 2003. U.S. gemstone production included agates, amber, beryl, coral, garnet, jade, jasper, opal, pearl, quartz, sapphire, shell, topaz, tourmaline, turquoise and other gem materials. More than 60 varieties of gemstones have been produced commercially from U.S. mines. But commercial mining of gemstones has never been extensively undertaken in the United States. Most of the deposits have been relatively small compared with other mining operations. In the United States, much of the current gemstone mining is conducted by collectors, gem clubs and hobbyists rather than business organizations.

Jan 1, 2005

German manufacturer DBT signed a contract to supply a sixth automated-plow long-wall system to Shenyang Coal in Liaoning province in northeastern China. This most recent order occurred just weeks after DBT signed a contract to deliver a fifth automated-plow longwall system to Datong Coal in Shanxi province. The plow will go into service at Shenyang Coal’s Hongyang Mine. Mining conditions at the mine, coupled with DBT’s advanced automated-plow technology, means that the system has the potential to become one of the world’s most productive thin-seam longwalls.

Jan 1, 2004

By Harry C. Verakis

A conveyor belt fire presents a serious safety hazard in an underground coal mine. A review of underground coal mine fires involving conveyor belts which occurred within the past two decades was made by the Mine Safety and Health Administration (MSHA). Belt fires that occurred during this period of time have burned as much as 610 m of belting before the fire was extinguished. In an effort to improve safety, MSHA has undertaken a program to study the flammability of conveyor belts in large and small-scale tests. Large-scale tests were conducted on various types of mine conveyor belts using a range of airflows from 0 to 6.1 m/s. Data were obtained to evaluate the effect of airflow on flame spread and other combustion properties of the conveyor belts. The results from the large-scale tests were utilized to develop a new MSHA laboratory-scale test for evaluating the flame resistance of conveyor belts used in underground coal mines. Agreement of results based on a pass/fail criterion was obtained between the large-scale test and new laboratory-scale test. A summary of test results from the new test is shown for different conveyor belt formulations. MSHA also performed a series of fire tests with wood samples using the new laboratory-scale tunnel apparatus. These tests were conducted at airflows from 0.5 to 5.1 m/s to determine the effect on flame spread and burn damage. The data were also analyzed to determine if wood could be used as a calibration standard. The results indicate the flame spread behavior of the wood follows trends similar to results obtained with conveyor belts. The data did not show the precision needed to use wood as a calibration standard. MSHA intends through rulemaking procedures to replace the "20g" conveyor belt acceptance test with the new laboratory-scale test. MSHA also plans to implement a voluntary acceptance program. Under this program, a. conveyor belt manufacturer could obtain an MSHA acceptance for belts meeting the new test criterion. A belt accepted under the voluntary program could then be used underground. Use of conveyor belts meeting the new test would limit the propagation of fire and reduce the probability of igniting other combustibles in the belt entry.

Jan 1, 1991

By J. Kim, H. Cho

The objective of the experiment was to investigate the efficiency of hindered-settling column in recovering carbon from anthracite. Two types of Korean anthracites were prepared for feed materials. Each sample was crushed and classified by size, and washability analyses were performed. Separation efficiency was evaluated under various operating conditions using a laboratory scale hindered settling column. Results showed that the carbon recovery was higher for the smaller sizes, but the purity of the product was better for the larger sizes. In, overall, 2-0.21mm particles of 40-45 % ash could be processed into about 20 % ash products.

Jan 1, 2002

By J. Garretson

When mining accidents occur, workers often become trapped and/or incapacitated. Current rescue operations can be dangerous and too slow to produce favorable outcomes. Currently, no method exists for rescue crews to scout ahead at critical times to assess the situation. Sandia National Laboratories (SNL), through a National Institute for Occupational Safety and Health (NIOSH) sponsored program has developed the Gemini-Scout mine rescue platform. The Gemini-Scout was created to assist in underground mine rescue missions. It has been designed to go into potentially hazardous environments to assess the conditions (structural, air quality, temperature). In addition, it will enable two-way communications with potential survivors prior to human rescue teams being able to enter the area. The Gemini platform is a dual tracked-chassis design, which gives the robot excellent mobility in unstructured environments. The design includes a passive 2-degree of freedom joint between two identical bodies allowing for ±30deg of pitch and roll. In addition to the base mobility platform, the Gemini-Scout incorporates many other features to help it succeed in its underground mission. The electronics are mounted in explosion proof housings to ensure safe operations in hazardous gas environments. The platform is also able to operate in up to 18in of standing water with its elevated pan/tilt cameras for navigation. A four-channel video link and Two-way audio on the vehicle help to ensure located survivors can communicate with the robot operators. The platform also incorporates a Mine Safety and Health Administration (MSHA) approved multi-gas sensor to monitor air quality. SNL believes that this technology is broad enough to be appealing to other first responders, such as police, firefighters and medical personnel. Gemini could easily be fitted to handle earthquake and fire scenarios, and it could provide relief in currently inaccessible situations.

Jan 1, 2012

The 18th annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held on Saturday, Dec. 2, 2000 at The Westin La Paloma in Tucson, AZ. The 2000 inductee, guest of honor and featured speaker at the banquet will be Ronald C. Cambre, chairman and chief executive officer of Newmont Mining. He will be honored for his role in positioning Newmont as an innovative and key player in the gold mining industry.

Jan 1, 2000

By S. Kittel, P. Galleguillos, H. E. Urtubia

The rougher flotation at Escondida consists of 80 cells of 100 m3 each, with injected air. Escondida has developed a system of automatic control of the rougher flotation using video cameras, which have been operating since 1997 for remote monitoring and manual control. Since 1999, an image processing software and a group of rules have allowed implementation of an expert system. To date, the expert system controls the superficial speed of each cell by adjusting the air flow and the froth depth of the flotation bank. Preliminary tests of the expert control on two of the eight rows gave 1.2% higher rougher recovery at a 92% degree of confidence. The proven benefits are already sufficient to move towards a complete plant implementation.

Jan 1, 2001

By Carsten Rühlemann, Thomas Kuhn, Cornelia Kriete

"Any economic calculation with respect to potential submarine mining activities requires reliable analytical data on the contents of valuable metals in these ores, including trace metals such as rare earth elements as well as Ti, Mo, V, Zr and Li. Due to the very special matrix of ferromanganese nodules (30% manganese oxides, 10-20% iron oxides, silicates; see Kuhn et al., this volume), their geochemical analyses pose a real challenge. Available ferromanganese nodules reference materials, e.g., NOD-P1 and A1, JMn-1, GBW07249, SDO-4 to -7 and NM2388, generally have only a few certified values for trace elements. Published data for these reference materials, collected in the GeoReM database (http://georem.mpch-mainz.gwdg.de/) are either rare for high technology metals or widely scattered for certain elements, especially the PGEs. Since most of these materials were released in the 1990s, many analytical procedures have seen significant advancement.In order to facilitate analytical quality assurance during exploration and potential future mining activities, the German Federal Institute of Geosciences and Mineral Resources (BGR) has contracted the Central Geological Laboratory of Mongolia (CGL) to produce a certified reference material for nodule analytics. Certified reference materials provide the highest level of reliability in geo-analytical measurements currently available and the CGL has a long-term experience in producing geological reference materials. Recently, the CGL was accredited as a reference material producer according to ISO Guide 34 by the American organization ACLASS (Assured Calibration and Laboratory Accreditation Select Services). Furthermore, it has been accredited as a testing laboratory according to ISO 17025."

Sep 1, 2014

By J. Hunter, E. Jackson

This paper describes work done by Placer Dome Technical Services Limited, a subsidiary of Barrick Gold, and Nautilus Minerals Inc. in support of the conceptual design of a subsea mining system. It describes an overall concept design plus specific studies into mechanical excavation at depth. The concept design includes one or more subsea excavators connected to a suction riser, which transports the cut material to a shipboard dewatering and offloading system. A multi-phase investigation was performed into the mechanical excavation of seafloor massive sulphides at depths of around 1600m. Rock samples were recovered and tested for rock properties and cutting behaviour. A small pick drum cutter was procured and tested on a representative concrete slab in a lab and tested again while submerged in a test tank. Finally the cutter was tested on a massive sulphide ore body at 1600m depth. The cutting performance results, e.g. pick forces and specific energies, should provide valuable input to the design of future full scale subsea mining systems.

Jan 1, 2007

By Steve Zaffron, Olga Loffredi, Eric Seedorff, Mary Poulton

"The New Face of Mining is a recognition of the central role of human beings in mining and the underappreciated power they can have in generating breakthroughs in business performance and shareholder value. The key is people creating, aligning on, and subsequently enacting the future of mining. A methodology that is effective creates a corporate environment for alignment to be possible and then transforms operations by embedding the necessary behaviors, processes and practices. The people within the organization then are empowered to find and to implement solutions quickly, as measured business results demonstrate in case histories of diverse mining challenges around the globe and over the decades.Urgent case for actionThe physics of mining does not change fundamentally over time, but the context in which it operates changes rapidly, periodically requiring a new face of mining. “The New Face of Mining,” which has been used as a metaphor for the campus-wide mineral resources research organization at the University of Arizona, has many facets, including societal, generational, technological, financial and environmental, but at the center, always, is humanity. The New Face of Mining is not necessarily about age, it is about people first imagining and then creating a new future for mining. The challenges facing the global industry evolve from year to year and differ in individual companies or mines at any one time.Quantified outcomes from case studies indicate that a methodology, now also offered annually in a four-day, open-enrollment leadership program tailored to the mining industry, is effective at generating breakthrough results in the mining business. Such challenges range from those with important technical components to others that are mostly social challenges. Our focus, however, is the centrality of people in aligning on and enacting the future of mining. We use the phrase New Face of Mining for leadership and ways to empower people in organizations that commonly are overlooked in the mining industry. Some of the material in this article is based on the ideas of Werner Erhard and on the book by Steve Zaffron and Dave Logan (2009), The Three Laws of Performance: Rewriting the Future of Your Organization and Your Life.At Davos, Switzerland in January 1992, nine visionary mining chief executive officers (CEO) gathered to create the Global Mining Initiative. Much has changed in the 26 years since that meeting:• The world GDP has increased from US$25.4 trillion to $75.8 trillion.• The annual number of U.S. patent applications increased from 186,000 to 629,000.• The number of websites has increased from 100 to 1 billion.• The number of academic references to artificial intelligence has climbed from more than 16,000 to more than 1 million.• The number of cell phone subscribers grew from 11 million in the United States to four billion globally."

Oct 1, 2019

By J. J. Gresham

Homestake’s first links with Australia were established in 1934 but it wasn’t until 1961 that the company established a formal presence in the country. After involvement and success in iron ore and nickel, Homestake made a strategic investment in the Kalgoorlie gold operations in 1975 and now owns 50% of Kalgoorlie Consolidated Gold Mines, operators of Australia’s biggest gold mine. In 1998 Homestake acquired the major Australian gold producer Plutonic Resources, is now firmly established as Australia’s second largest gold producer and is actively seeking further opportunities for growth in the Austral-Asia region. Homestake’s success in Australia has been the result of important strategic alliances, timely investments, a long term commitment to the region and perseverance during periods of depressed commodity prices.

Jan 1, 2001