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By Harvey P. Knudsen

This paper describes the results of a comparative study of the geostatistical ore reserve estimation method over three conventional methods; the polygon method, the inverse of the distance squared (IDS) method, and ELIP which is similar to IDS. Each method was evaluated on its ability to accurately predict individual block grades for one bench of the Pima Nine, located near Tucson, Arizona. Results at the Pima Mine indicate that the geostatistical method is no better nor worse in predicting block grades and total tonnage than the ELIP or IDS methods in contrast, the polygon method is clearly inferior. All of the methods would have given better results if geology had been included in the block model. At already producing mines ELlP or IDS may be good choices since they involve substantially less cost in computer time. For prospective or new properties, the geostatistical model is more attractive, due to its ability to construct confidence limits on the estimates.

Jan 1, 1976

By William R. Yernberg

The current state of the copper industry was the topic of discussion at the Copper 99 — Cobre 99conference held Oct. 10 to 13, 1999, in Phoenix, AZ. More than 700 copper-industry engineers, executives, consultants, academics, vendors and other interested parties attended. This successful and well-organized conference was the fourth in a series of international conferences devoted to the mineral processing and extractive metallurgy of copper. The 1999 meeting marked the first time that the conference was held in the United States. The meeting was co-organized by the Minerals, Metals and Materials Society (TMS); the Chilean Institute of Mining Engineers (IIMCH) and the Metallurgical Society of the Canadian Institute of Mining, Metallurgy & Petroleum(CIM). The meeting was also sponsored by The Society for Mining, Metallurgy and Exploration Inc.

Jan 1, 2000

By D. R. Spears

Conventional round tank thickeners have been widely used in the mining industry for many years. The mining industry was well satisfied with the ability of conventional thickeners to improve minerals beneficiation operations. However, development of improved flocculants (the polyacrylamides) made possible much more rapid settling rates, since polyacrylamides produce large flocs rapidly (unlike starch or inorganics). Traditionally considered to be a slow operation if maximum underflow density was achieved, and therefore there was some justification for the expense. Thickeners required large volumes to permit sufficient time for settling. The oversize not considered a drawback but the initial capital cost was. In high rate thickeners, a bed of thickened material is allowed to build around the feedwell, even above the bottom of the feedwell. The slurry is fed directly into the bed at a velocity that allows the material to be evenly dispersed over the thickener area This more efficient use of settling area allows a higher solids throughput per unit surface area (rise rate). In this paper, high rate thickener rise rates and polymer consumption are compared.

Jan 1, 1998

By Susan L. Bednarz

Recent advances in digital cameras and image processing allow photographers to produce excellent high-resolution action shots in low light and high contrast conditions commonly encountered underground. Digital photography is often used for construction and inspection documentation for underground structures. Designers, owners, and contractors benefit from quality photographs that document incremental progress and project milestones. Documentation photos serve as a lasting record of as-built conditions, are an important marketing tool, and help the owner build public support for expensive public works projects. When the project is complete, the only mementos that the participants will hold onto are the photographs.

Jan 1, 2008

By S. Holtermann

Through the process of Riverbank Filtration (RBF), the Louisville Water Company plans to obtain a higher quality source of water for their B.E. Payne Water Treatment Plant (WTP) by means of four collector wells located in the alluvial aquifer along the bank of the Ohio River. The collector wells are connected to a 2,850 L/s (65 mgd) pumping station by a 2,362 m (7,750 ft) long, 3 m (10 ft) finished diameter tunnel located in limestone and shale bedrock, which is approximately 45 m (150 ft) below the surface. High tunnel boring machine (TBM) production rates were achieved in this moderately weak bedrock; most of the tunnel only required support in the crown. An unanticipated water-bearing fault and unanticipated ground behavior proved challenging and required quick thinking to minimize impacts to construction. Tunneling conditions are discussed in detail, together with the methods used for overcoming the groundwater and ground behavior challenges. The tunnel is expected to be completed in April 2009.

By Richard P. Killmeyer, Carl P. Maronde, W. W. Wen, Peter J. Suardini

Under a cost-shared Department of Energy contract, awarded as part of the Coal Preparation Program&apos;s High Efficiency Preparation subprogram, Custom Coals International will be installing and testing a 227 kglhr micronized-magnetite cycloning circuit in PETC&apos;s Coal Preparation Process Research Facility. The project includes the design, construction, testing, and decommissioning of a fully integrated circuit complete with feed coal classification to remove the minus-30-micron material, dense-medium cycloning of the 300 by 30 micron feed coal using micronized magnetite (<10 microns), and medium recovery via drain & rinse screening and various stages and types of magnetic separation. This paper will describe the micronized-magnetite beneficiation technology and the scope of work for this project including an update on the status of the project, the circuit, and the proposed test plan.

Jan 1, 1995

By S. P. Sandoval

In 2002 the Freeport-McMoRan Technology Center undertook research to develop a lower-cost alternative to guar for cathode smoothing in copper electrowinning. The work was conducted at the Technology Center?s SXEW Test Facility located in Morenci, Arizona. Bench-scale copper electrowinning cells were designed and implemented to screen a number of potential polymers for cathode smoothing. These included modified polysaccharide polymers that were nonionic, cationic, and anionic in nature.

Jan 1, 2010

By T. Klemetti, W. H. Su, M. A. Van Dyke

Entry stability in coal mines is dependent on geologic conditions and engineering controls. Most engineering controls in ground control are predictable and standardized for typical geologic conditions. However, geologic anomalies may exist that are difficult to detect with traditional core hole drilling. Borescopes offer a cost-efficient way to gather more geologic data between core holes. Additional data obtained from borescope results provide a clearer picture to enhance detection of hazardous conditions due to geologic anomalies. The equipment, methods, and analysis of borescope results provide geomechanical engineers with a clear understanding of strata behavior and the best information to implement roof control plans and supplemental support to enhance miner safety and health. INTRODUCTION Borescope technology has changed very little since its inception. However, the idea to use borescopes to examine roof strata started with the U.S. Bureau of Mines in 1979 with the production of a fiber-optic borescope (FitzSimmons, et al., 1979). The first documented use of a borescope in the coal mining industry began during the 1980s in Australia by researcher John Shepherd. Shepherd’s idea was to use a borescope to collect a series of data points from the roof lithology and compose a geologic cross section. The cross section was then used to identify key features that suggested the beginnings of roof failure. The features Shepherd identified were bedding plane separations in the roof and low angle, extension, and tensile failures. Shepherd also suggested that the borescope findings could be used for geologic mapping for lithological variation, fracture distribution, and determining if supplemental roof support was needed (Shepherd, et al., 1986). In the United States the first publication about borescope usage for coal mine stability assessment was by Su and associates in 1999, who specifically related the combination of using borescope, geophysical, and corehole data to produce geologic hazard maps (Su et al., 1999). This work directly linked the usage of a borescope with the design of supplemental roof support. The use of borescopes in mining was adopted industry wide by the 2000s. Operator case studies were being published using borescopes to aid in supplemental support recommendations and hazard mapping. An Australian study published in 2007 based the optimization of secondary support after each longwall pass on the results of borescope data. The study stated that the borescope was an invaluable tool for understanding roof behavior (Black, et al., 2007). In 2009, a publication by the National Institute for Occupational Safety and Health (NIOSH) took the concept of borescoping one step further. The work centered around creating a roof quality index (RQI) for limestone mines based on borescope data. The RQI attempted to assign a ranking to establish the nature of the roof and its stability (Ellenberger 2009). In theory, this would have been a very useful tool, but the RQI system has not been widely adopted in the industry.

Jan 1, 2019

By M. A. Ouederni, G. C. Chorosz, E. P. Déliac

This paper deals with the heat flow problems in deep workings (depth greater than 1000 m in France). The approach benefitted from experience gathered in France and South Africa. Deep mines are located in the East of France (coal in Lorraine and potash in Alsace), where the geothermal gradient can reach 4 &apos;C per 100 m (Virgin Rock Temperatures, VRT, around 50 &apos;C). This paper is concerned with the following topics: method of studying the heat flow problem on a mine-wide basis, specific models for heat and moisture pick-up, interfacing of heat and ventilation calculations and a case history in the Lorraine collieries. The heat flow problem on a mine-wide basis is studied in a fashion similar to ventilation networks. Each branch is considered as a "black box" where the air picks up heat and moisture (or is cooled, in the case of an air-cooler). Each box is therefore modeled as a heat transfer unit, hence the calculation of outlet temperatures (wet- and dry-bulb) from the intake ones. The whole network can thus be computed as a sequence of boxes from the air intakes towards the outlets. The second section reviews a number of models used for the assessment of heat and moisture pick-up in the "boxes", with emphasis on stopes and development ends, which are particular to the mining method in use. Two types of stopes are considered: longwall (horizontal and inclined) and cut-and-fill (subvertical). Mechanized rock breaking and blasting can be accounted for. A particular attention is given to development ends, especially complex from the heat flow point of view (rock characteristics, wetness factors, etc.) and usually quite hot. These workings, which are critical in order to secure new production areas, are studied on an average basis as well as in extreme conditions. The calculation takes into account the history of rock temperatures. The interaction between ventilation and thermodynamic calculations is still under development. The idea consists of coupling ventilation calculations with the "box" models: the first step determines the direction of air flow, hence the sequence of the boxes; thereafter the calculations yield the effect of temperature and presssures on air flows. The final section reports on the validation of the whole approach against field data. It concerns several heat flow surveys aimed at checking the models for shafts, stopes and development ends. The accuracy of the method is found very satisfactory.

Jan 1, 1987

By P. D. Georgescu

Gold, like no other metal, has a fascinating and special place in the world. It is used in a range of every day applications essential to modern life. Gold has long been considered the most precious metal in the world. Gold is used mainly for making jewellery as well as for dentistry, adornments on building and artistic expression. For thousands of years it has been used as an ornament of kings, a currency and standard for global currencies, and more recently, in a wide range of electronic devices and medical applications. Gold?s many unique properties have secured in a central role in history and human development. Today, more often than not, gold is extracted from ores. It occurs in vein and alluvial deposits and is often separated from rocks and other minerals by mining and processing operations. Some of these processes cause environmental concern (cyanidation, amalgamation, roasting). Besides primary gold ore resources, a series of secondary resources can be taken into account and processed for gold and silver recovery. There are two main types of waste produced. The first type is process waste, which includes tailing consisting of processing residues and waste rock. The other type is refuse from other different processes and recyclable materials. Among other secondary resources and/or by-products containing precious metals, which have been studied some processes and technologies with low ecological impact are presented in this paper. Heaps and tailing ponds resulted from gold-bearing ore exploitation and processing, refractory gold-bearing pyrite concentrates, slag resulted from electrolytic slime melting, gold-bearing chlorous slime are taken into account. In order to establish environmental friendly technologies for precious metals recovery from these secondary resources, laboratory experiments have been carried out on a pilot scale and in some cases on semi-industrial scale by applying specific technological processes, namely hydro-gravitational concentration, bio-oxidation, non-ionizing electromagnetic radiation (microwaves), solubilization without utilizing cyanide and gold recovery by ion-exchange resin. This paper presents the research results, technological principles as well as the possibilities of applying combined processes in order to treat different secondary gold-bearing resources.

Jan 1, 2006

By Z. Rogovin

In order to develop more accurate procedures for scale-up and design of semi-autogenous-grinding mills through detailed mathematical models, a better understanding of the charge motion and rock/ball segregation is needed. To achieve this a 0.61 m (2.0 ft) diameter x 0.305 m (1.0 ft) length plexiglas mill was constructed as a scale model of a commercial SAG mill. Rock motion in the rotating mill was simulated using various sizes of ceramic balls. Quantitative measurements of dynamic angle of repose, water and slurry motion, holdup and size segregation of the charge were taken. In addition, a video-presentaiton (available to the public) was prepared to elucidate charge and water motion at various mill speeds, charge volumes, rock size distribution and flow rates.

Jan 1, 1985

By H. Sato, B. Thornton, K. Nishi, A. Usui

"Northwestern Pacific submarine seamounts are believed to be future marine mining areas of ferromanganese crusts, which contain hi-tech industrial metals, such as Co, Ni, Te, Ti, Pt, and REEs. The Takuyo No. 5 seamount is a member of the Cretaceous super-plume seamounts in the north Pacific, located within a Japanese EEZ (100 nm from the Minami- Torishima Is. or Marcus Is.), and only 300 nm away from the Japan’s Licensed area for exploration of Co-rich ferromanganese crusts under the ISA. This is an on-going program supported by independent academic communities but not a state-run program or managed by private funding.We have observed, sampled, measured, and analyzed the occurrences, distribution, physical properties, and microbiological environments at a selected flat topped seamount named Takuyo No.5 as a model area for scientific study of ferromanganese crusts within the Japanese EEZ. We then characterized crust structures, composition, age, and growth history, resulting in an understanding of the overall nature and distribution of these deposits from wide range of areas, water depths and geological environments. The study started with a ROV (Hyper-Dolphin 3K of JAMSTEC) exploration jointly with universities and national institutions (Japan Agency for Marine-Earth Science and Technology, Japan Oil, Gas, and Metal Exploration Corporation, and Geological Survey of Japan) in 2009 using marine geology vessels, remotely-operated vehicle, an oceanbottom drill machine, deep-tow TV camera, as well as conventional dredges and corers. We have been studying the topography, geology, nature of the bottom material of the seamounts using delicate sampling devices and measurement tools, and characterized the distribution patterns of the metal-rich ferromanganese deposits from chemical, mineralogical, and microbiological points of view."

Sep 1, 2014

By L. Neuman

Reclamation and permit applications for mines tend to be very detailed and complicated documents. Depending on its complexity, the application may have to be reviewed in detail for water quality, water quantity, wetland and upland habitat, wildlife issues, waste disposal, historical and archeological significance, other environmental factors, and financial surety sufficiency. To reduce review time and cut costs to the applicant, this paper identifies the most common mistakes that can lead to delays in the application process.

Jan 1, 2004

By S. J. Ristorcelli

Historically, geologic data has not been adequately considered in resource estimation. More recently, with the use of computers and sophisticated estimation algorithms and geostatistical justifications, geology has been downplayed further. Many reasons are given for not using geology including cost, time and irrelevance. None are valid. Boundaries defining mineral domains should be used in computer-generated resource estimates. Selected case histories show how the failure to honor geology has caused discrepancies in resource estimates of actual in-place resources. After-the-fact differences have included decreases in tonnage of up to 50% and increases up to 300%; partial to complete recategorization of material; and 50% decreases in grade. The costs of gathering and using geology are trivial compared to the potential consequences.

Jan 1, 1994

By Alphonce Wikedzi, Mussa D. Budeba, Samwel V. Manyele, Sospeter P. Maganga

The present study provides an overview of the challenges and opportunities in processing complex gold-copper ores. The systematic literature review was conducted using Scopus database and seven-step methodological approach. The study indicates that the major challenges in processing complex gold-copper ores through the conventional cyanidation method include (1) increase in cyanide consumption; (2) increase in cyanide destruction cost; (3) low gold recovery; (4) decrease in adsorption efficiency; (5) decrease in electrowinning efficiency, and (6) difficulties in the measurement of free cyanide concentration in the leaching system. Moreover, the study indicates that several methods have been developed and some have been implemented in the mining industry for processing complex gold-copper ores. This includes ore segregation, pre-aeration, pre-treatment methods (e.g., ammonia), alternative lixiviants (e.g., thiosulfate, thiocyanate, glycine), cyanide destruction methods, and cyanide and copper recovery technologies. The study concluded that using lixiviant mixtures (e.g., cyanide-glycine), pre-treatment with environmentally friendly reagents (e.g., glycine) and the integrated membrane-based process (SuCy process) are new directions in processing complex gold-copper ores. However, more investigations are required to advance these processes to a commercial scale.

Sep 30, 2023

By Yoichi Shimada, Katsuyuki Nishida, Shinichi Takahashi, Yasushi Okada, Yohei Nakamichi, Kazunori Oshiro, Taichi Terui, Sigehiko Sugie

"Temporary retaining walls are ordinarily used for tunnel construction work conducted using the opencut construction method. Retaining walls in such instances are typically installed vertically. However, shoring (such as struts and king posts) is required to ensure the stability of retaining walls in cases of excavation work to depths that exceed approximately 4 m. A new design and construction method that focuses on the effectiveness of retaining walls that are installed on an incline was studied with the aim of improving construction workability by omitting shoring. The inclined braceless excavation support (IBES) method, which was developed for use with the inclined buttress method, requires no shoring, even for deep-open-cut construction work and can be applied to deep excavation work on ground with a high groundwater level. This method has been applied at six work sites in Japan in recent years. This paper introduces the IBES design and construction method and presents verification results based on the design method, a model experiment, finite element analysis, and measurements obtained during construction work.INTRODUCTIONBackgroundIn the past, temporary retaining walls used in open-cut construction work have been installed vertically, and shoring (such as struts and king posts) has typically been used to ensure the stability of these retaining walls when the excavation depth reached 3–4 m. However, shoring interferes with structures built within excavations and requires box-outs and penetration sections in the structures, as well as concrete joints that raise concerns about their impact on the watertightness and long-term durability of structures (Figure 1).Shoring also narrows the space available for conducting construction work and reduces construction work efficiency, and the installation and removal of shoring increases the construction duration and cost. As a result, there has been a demand for ways to reduce or eliminate shoring to improve the quality of structures and construction work efficiency."

Jan 1, 2016

By B. K. Mishra

The motion of the charge inside a grinding mill is of considerable practical importance. The dynamics of grinding mills have been the subject of study by a number of workers because it can accurately predict: i) the power drawn by the mill, ii) the distribution of forces inside the mill, and hence the wear rate of balls as well as the liners, and iii) mass transport of milled product through the porous ball charge. Some of the earlier analyses of the motion of a charge of particulate material in a tumbling mill were reported by White (1904), Davis (1919), and Dyer (1945) and have been reviewed by Rose and Sullivan (1958). In these works, frictional force at the wall of the mill and between the colliding balls, and the interaction of different ball trajectories, was not considered. Moreover, it was assumed that the profile of the tumbling charge is independent of the degree of filling, which is generally not true. However, all this work led to the identification of so-called "equilibrium surface" which is the plane that separates the rotating charge into two regions. The inner region is static; here there is no motion relative to the mill shell. The other region is a shear region where either the balls flow down the surface of the charge (cascading motion), or are projected out of the surface and follow approximately parabolic paths (cataracting motion).

Jan 1, 1990

By C. J. Ferron

Gold occurrence in operating plant tailings ranges from gold in solution, fine free gold, gold associated with sulphides/arsenides/tellurides and gold occluded within iron oxides or arsenates and silica gangue. This paper briefly presents various alternatives to reprocess gold tailings, with examples. These include the use of centrifugal gravity separators, CIL, magnetic separation, flotation and pressure oxidation.

Jan 1, 1993

By Craig Allan

Underground construction environments, especially those with limited airflow such as shafts, cross passages, and stations, necessitate effective dust control. This requires combining existing measures with adapted approaches for more efficient and productive operations, cleaner jobsites, and decreased worker exposure to contaminated air. This paper will discuss new configurations and trends in dust collection on Australasian infrastructure projects including WestConnex, Melbourne Metro Tunnel and City Rail Link, all of which have applied innovative methodologies for mobile at-source dust collection. Mobile dust collectors can be track-mounted dust collectors operate alongside equipment, use hydraulic stepping systems to advance with roadheaders, or compact castor-mounted units are used within cross passage confines.

Dec 1, 2022

By E. Iasillo, R. R. Carneiro

Independent of the method chosen to forecast production, an accurate method to project metal extraction is needed in order to accommodate leach cycles that exceed leach data on hand and thus be able to accurately forecast production. Metal extraction data must be developed for each ore type identified in the deposit in order to apply the correct rate of leaching when a specific ore is being treated. Curve fitting is used to model the rate of disengagement of metal into the pregnant solution. This paper provides a description of a curve fitting algorithm developed by Mr. John T. Bartlett, inventor of the METSIM™ process simulation program. A methodology is provided by which the metallurgical data developed is evaluated to determine if accurate projections may be made from the data. A criteria has been developed to help determine when a column experiment may be terminated.

Jan 1, 2001