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A number of mineral deposits occur in close proximity to the Pacific plate fronts. Among these deposits are gold-silver and the base metal sulphide deposits of copper, zinc and lead. Gold deposits that commonly occur in these areas are of hydrothermal origin. Of these the epithermal deposits have attracted the attention of the exploration geologists as well as the metallurgists. One vital aspect of the activity of the geologists is the development of models for epithermal gold mineralisation in the Pacific Rim. These models can also be used by metallurgists for predicting gold extraction processes. This paper reviews the mineralogy, fineness and the host minerals of gold and examines the data in the light of gold mineralisation in the southwest Pacific Rim. The gold mineralisation models proposed for the Pacific Rim have been used to predict gold extraction processes suitable for the various mineralisation types. Discussed also are the mineralisation and treatment processes of some selected epithermal gold deposits and gold-rich porphyry copper deposits in Indonesia, Papua New Guinea, Solomon Islands, Fiji and New Zealand.

Jan 1, 1999

By David E. Thompson, Andrew F. McKown, Herbert H. Einstein, Amr S. Azzouz

INTRODUCTION Design of supports for underground chambers in rock has undergone considerable development. This becomes evident when comparing support dimensions of subway station caverns built in the U.S. over the past fifteen years. The Porter Square Station cavern, which is a part of the Massachusetts Bay Transportation Authority (MBTA) Red Line extension, is the latest in this series. It is approximately 168 m (550 ft) long, 21 m (70 ft) wide, and 14 m (45 ft) high, and has a permanent support of light steel ribs imbedded in a 0.4 m nominal (15 in) shotcrete lining. An extensive construction control instrumentation program made it possible to evaluate the performance of the cavern and its support. This evaluation, which is presented in this paper, was the objective of a research project sponsored by the Urban Mass Transportation Administration (UMTA) and jointly conducted by Haley and Aldrich, and MIT. The actually used design procedure was compared with other approaches, notably procedures based on Finite Element analyses and empirical rock mass classification methods. Support dimensions predicted with all these approaches were compared to the actual support and its performance.

Jan 1, 1983

By L. G. Stolarczyk, Y. Luo, S. S. Peng

Detection and assessment of severe geological anomalies ahead of a longwall face greatly benefits the mining operation. Electromagnetic-based Radio Imaging Method (RIM) is one of the most promising geophysical methods for this task. Based on two decades of development, the latest RIM instrumentation (RIM-IV) has expanded its operational range up to 1,800ft.A site demonstration of the RIM-IV technology was recently conducted within a longwall panel. An extensive ground truth study was performed to evaluate the accuracy of the RIM survey results. This study compared the generated RIM tomograms of attenuation rate with the mapped geological anomalies. Three different approaches have been employed to examine the accuracy of the RIM results and to correlate the measured signal attenuation rates with physical properties of the coal seam. The study shows that the RIM-IV technology is able to identify and delineate those geological features that would severely affect the longwall mining operation.

Jan 1, 2004

By Tano Balbin, Valery Astakhov, Juha Timperi, Lauri Koresaar

"Online elemental analysis is the basis of optimal flotation control in mineral concentrator plants. Traditionally XRF analyzers have been used as the online analysis method. However, online XRF analyzers struggle to measure elements below calcium in atomic number (Z=20). For many processes lighter element assays would be beneficial to improve control of grade and recovery. Processes where elements below Ca are required include P, Mg and Si in phosphate concentrators, Si, Mg and Al in iron concentrators, and S and C in gold concentrators. Laser-Induced Breakdown Spectroscopy (LIBS) based elemental analysis can readily be applied to these processes. LIBS is based on generating plasma in the slurry sample by a high energy laser and analysis of the plasma by optical emission spectroscopy. Capabilities of a new Courier® 8 analyzer based in LIBS technology are demonstrated for elemental analysis starting from lithium (Z=3). Results of a plant installation in a sulfide gold concentrator provide a good agreement with the analyzer and laboratory assays.IntroductionEffective process control can be regarded as one of the fastest paying investments for a mineral processing plant. Process optimization in flotation circuits requires constant feedback of the process state. If only manual laboratory samples are available, this optimization becomes difficult due to the long delay between taking the sample and acquiring the laboratory result. If the element grades are available in online basis, the operator or automatic process control system can make corrective actions in real time.Online X-Ray Fluorescence (XRF) analyzers have been in use at concentrators for decades. The XRF analyzers can provide a fast, accurate and precise analysis from slurry streams. However, the drawback of XRF analyzers is their lack of capability to measure elements below Ca (Z=20) in atomic number. The low energy X-rays of the low atomic number elements get absorbed by water in the sample, protective window of the analyzer, or air between the sample and spectrometer."

Jan 1, 2017

By K. Thuro, R. J. Plinninger

ABSTRACT: Determining tunnel stability is a key issue during preliminary site investigation. In contrast, problems of excavatability have been largely ignored. While the choice of an economic tunnelling method is admittedly a clear priority in the planning stage, special investigations focus-sing on rock fragmentation (e.g. drilling or cutting performance, rock mass blastability or tool wear) are rarely carried out. This paper explores possibilities to quantify key parameters for rock mass excavatability in drilling, blasting and cutting by TBMs and roadheaders. RÉSUMÉE: La détermination de la stabilité du tunnel est une question clé lors des études prélimi-naires. En revanche, les problèmes d'excavabilité sont souvent en grande partie ignorés. Tandis que le choix d'une méthode de percement économique est évidemment une priorité claire dans l'étape de planification, des investigations spéciales se concentrant sur la fragmentation de la roche (par exemple le comportement de la roche au forage, à l’excavation ou au dynamitage et l’usure des outil) sont rarement effectuées. Cet article explore les possibilités pour quantifier les paramè-tres clé de la roche lors d’excavation par forage, dynamitage, au tunnelier (TBMs) ou à l’excavatrice. ZUSAMMENFASSUNG: Beim Tunnelbau wir meist die Vorhersage der Stabilität des ausgebrochenen Hohlraums als Schlüsselfragestellung betrachtet. Im Gegensatz dazu werden Probleme der Gebirgslösung weitgehend ignoriert. Während der Wahl einer wirtschaftlichen Vortriebsmethode während der Planungsphase meist noch eine gewisse Priorität beigemessen wird, werden spezielle Untersuchungen zur Gebirgslösung (Bohr- oder Schneidbarkeit, Sprengbarkeit oder Werkzeugverbrauch) nur sehr selten durchgeführt. Diese Publikation zeigt Möglichkeiten der Quantifizierung von Schlüsselparametern für die Gebirgslösbarkeit auf, also der Bohr- und Sprengbarkeit, der Fräsbarkeit mit Teilschnittmaschinen und der Schneidbarkeit mit TBMs.

Jan 1, 2003

By F. Hassani, K. Moozar, J. Ouellet, P. Gauthier

"This paper describes a sudden spill of waste rock used for backfilling from a waste pass at an underground mine in Canada, thus causing a major failure/accident. The mine operator immediately launched a detailed investigation to understand the causes of this accident and develop procedures to prevent any recurrence of such events in the future. The authors from McGill University were invited to collaborate with the engineers at the mine to examine this accident. The events leading to the accident were studied, appropriate measurements were taken and samples of the waste material were collected for further testing and analysis.The field visit and the interview of the witnesses allowed the detailed documentation of the events. The sequence of events related to the incident, along with the experimental results obtained in the course of the investigation, are presented. The waste material was characterized in the laboratory with regard to its behaviour in the presence of water. This information is discussed and the failure mechanism involved in the accident is identified. Finally, the full recommendations as well as the immediate operational measures implemented by the mine to prevent the future occurrence of such events are presented and discussed."

Jan 1, 2004

By D. Harrington

The record of fatalities from mine explosions in the United States during the past 44 years has been the best in the history of the mining industry, despite the fact that the number of fatalities from this cause during the past fiscal year now is nearly double that of the previous year. During there 4 fiscal years, mine explosions have resulted in an average of 45.5 deaths per year, compared with an average of 153 deaths per year for the preceding 5 years; an average of 542 deaths per year for the 3 years 1907-1909, inclusive, and a yearly average of 265 deaths per year for the 20 years prior to 1929. Other types of mine accidents also have been reduced during this period, but not to the same degree or by as large a percentage as mine explosions. The fact that in this fiscal year ended June 30, 1937, electricity was responsible for 60 percent of the explosions and 85.5 percent of the fatalities resulting therefrom (see tables 3 and 4) is evidence that either mine operators are lax in providing proper electrical equipment or there is laxity in the upkeep and use of electricity in our mines and more particularly in our coal mines. Several large coal-producing States that in the Fast have had numerous disastrous explosions have been free from such disasters for continuous periods of as long as 8 years. The bituminous mines of Pennsylvania, one of the largest coal-producing States, give a good example of what can be done to prevent explosions. 'his State, with its large number of operating mines, many with very definite hazards from gas or dust or both, has had only two major explosions (resulting in 16 fatalities) during the past 7 years; this is a decidedly good record compared with any similar period in the past and when it is considered that during this period about 750,000,000 tons of coal have been produced. Other good records are: Tennessee, without a single fatality from explosions during the past 9 years; Alabama, with 6 fatalities during the past 7 years; Illinois, with no explosions during the past 4 years; and

Jan 1, 1938

By J. Asfahani

"The Schlumberger configuration used in geoelectrical sounding is slightly adapted here to obtain reliable data for both shallow and deep penetration depths from the same survey. In this configuration, two kinds of current electrode half-spacings are used: the first enables construction of vertical electrical resistivity sounding (VES) curves for shallow depths (<50 m), and the second for depths =250 m. For a given VES location, two field curves are measured and interpreted using two standard approaches. Practical characteristics of such a modified configuration are illustrated with two field applications in Syria. The first aims to characterize the structure of Quaternary and recent deposits in the Al-Ghab depression region, and the second deals with exploration for phosphatic sedimentary units in the Al-Sharquieh mine. La configuration de Schlumberger normalement employée dans les levés géoélectriques a été légèrement modifiée afin d’obtenir des données fiables à faible et forte profondeur durant le même levé. Dans cette nouvelle configuration, deux types de demi-espacements des électrodes sont utilisés : le premier permet le développement de courbes de sondage de résistivité électrique verticales (REV) pour les faibles profondeurs (<50 m), et le second atteint des profondeurs =250 m. Pour une localité REV donnée, deux courbes de champs sont donc mesurées et interprétées grâce à deux approches standardisées. Les caractéristiques pratiques de cette configuration modifiée sont illustrées par deus exemples d’application en Syrie. Le premier vise la caractérisation de la structure des dépôts Quaternaires et récents de la région de la dépression d’Al-Ghab, et le second traite de l’exploration pour des unités phosphatiques sédimentaires à la mine Al-Sharquieh."

Jan 1, 2009

This paper describes certain analytical methods used at the Rosepery Mine and Treatment Plant of the Electrolytic Zinc Co. of Australasia Ltd., which are not generally in use and may therefore be of more interest than a description of the normal routine methods which are used in most of the mining assay laboratories of the Commonwealth, and which have been published previously.The ore mined and treated at Rosebery is of a complex nature and demands closer control in the concentrating plant than is necessary on some other similar mining fields.It is necessary for the mill shift supervisors to keep constant control on the grade of lead and zinc concentrates produced on their respective shifts, and further, it is essential to maintain an economic compromise between grade of concentrates and the recovery of the particular concent:t:ate. This necessitates a more frequent check on concentrate grade tp.an is provided by the daily assays carried, out by the assay office. Rather than employ trained ,assayers on shift work, &quot;quick methods&quot; of analysis, which could be carried out by the operators, &apos;were adopted.&apos;In such methods, it is desirable that the necessary manipulation should be reduced to the following:-a. Taking the sample, drying and mixing.b. Weighing the necessary amount of sample-for assay.c. Adding the reagents for use in the assay without change of beakers.d. Titration and calculation.Such a contraction of, the normal technique would be impracticable for many determinations, but in the case of lead...

Jan 1, 1949

By Russell Clough

The Pacheco Pumping Plant is situated on the west end of San Luis Reservoir in western Merced County, California. It is designed to draw water from the reservoir and pump it into a 3,500,000 gallon regulating tank. The water then flows entirely by gravity to the Coyote Pump Station in Morgan Hill, a distance of 40 miles, where it is pumped into Anderson Reservoir. This water is used to recharge the depleted groundwater table in the Santa Clara Valley. Eventually, some of the water will be diverted to Hollister in San Benito County and to Watsonville and Santa Cruz in Santa Cruz County. The owner is the United States Bureau of Reclamation. The underground work consisted of a fifteen foot finished diameter surge shaft 250 feet deep to the crown of the pump chamber; a twenty foot finished diameter pump chamber which declined from the shaft at 14.2% for ninety feet and then ran horizontally for 180 feet; and twelve each five foot diameter steel lined intake shafts 240 feet deep which intersect the pump chamber in the horizontal section. (Figure 1) Upon completion of the pump chamber, the contractor had to dewater the existing tunnel under the reservoir, excavate the remaining fifteen foot plug, and concrete the transition. The low bidder for this contract was Underground - Continental-Heller at 414,456,000. Excavation of the open cut for the pumping plant and surge shaft began on April 14, 1983. This was performed using a Koehring 1066D backhoe, dozer, trucks, and two Cat 631 scrapers. The excavation was started at the surge shaft so that the grouting could begin

Jan 1, 1985

By Carl Sunderman, Steve Signer

Researchers at the National Institute for Occupational Safety and Health (NIOSH) have developed several new tools for evaluating roof support performance. A miniature data acquisition system (MIDAS) was developed that can collect readings from up to 16 strain gauges at regular time intervals and store the readings for later retrieval. Three LED lights change from green to yellow, then red, based on the reading levels and/or rates of change of rock movement. This feature can be used to warn miners of rock instabilities. The system can be used with any strain-gauged support (resin bolt, friction bolt, cable bolt) or with a newly developed rock strain strip (ROSS) developed by NIOSH to measure rock strain. A ROSS is grouted in a hole drilled adjacent to the rock support to be evaluated; the deformed shape of the ROSS provides anchorage on either side of the strain gauges. Data from both laboratory tests and field evaluations are presented that describe the capabilities of both the MIDAS and ROSS instruments.

By F. Calizaya

The PT Freeport Indonesia‘s Deep Ore Zone(DOZ) copper deposit is located in the province of Irian-Jaya, Indonesia. Currently, a block cave mine is being developed around this deposit. Production is scheduled to start in year 2000 and to ramp up to25,000 tpd by year 2003. The air quantity requirement for this mine is equal to 780 m3/s. To supply this quantity, the mine will require five centrifugal fans (one 450 and four 750 kW fans). This study summarizes the technical aspects related to the installation and commissioning of one of these fans. The fan was installed on the surface in a parallel arrangement with two others. It has a design capacity of 240 m3/s of air at 2.2 kPa of static pressure. The study presents the installation details from the underground shaft excavation and portal development through fan testing and commissioning. It also presents the results of a monitoring system that was installed to determine the fan duties.

Jan 1, 2000

By F. A. Olson, S. L. Pohlman

A unique method of measuring weight loss as a function 3 of time, with a sensitivity of 10-5 grams, while leaching copper minerals with a flowing acid leach solution has been developed. Kinetic results obtained coupled with visual and microprobe analyses show topochemical reaction for the leaching of chrysocolla with sulfuric acid. The kinetics follow a shrinking core model and show ion diffusion through a product layer, chemical reaction at the unreacted core interface and mass transfer through the boundary layer as being important.

Jan 1, 1974

By Ghosh I, Vanangamudi M

Experiments have been made in a laboratory heavy media separator at various specific gravities of separation using zinc chloride solution and magnetite suspension as media for different types of coals. The results indicate that the magnetite bath gives at better separation than zinc chloride solution. Even though the probable error remains the same for most conditions of operation, the error area is found to have a wide variation which emphasises the importance of the error area over probable error in evaluating the performance of a cleaning unit.

Jan 1, 1981

By I. Demers

Doyon mine, Quebec, Canada evaluates the possibility of desulphurizing their tailings to produce material to be used in as cover over the acid generating tailings disposal site. Laboratory tests were conducted and showed that a single-layer cover made of desulphurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modelling with the software Vadose/W was undertaken to optimize the design parameters, namely cover thickness, water table position, and residual sulphide content of desulphurized tailings following laboratory work. It was found that the optimal configuration includes a 1 m desulphurized tailings cover containing 0.8%S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux towards acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective chosen for Doyon mine (10 mol/m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2008

By K Kermanshahi, J Allen, MáHilden, M Powell, S Mwansa, S Palaniandy

Approximately 420 VertiMills« (VTM) have been installed in mineral processing plants throughout the world, mainly in tertiary and regrind applications plus several in secondary grinding duties. Metso Minerals (Metso) and the Julius Kruttschnitt Mineral Research Centre (JKMRC) have commenced a collaborative research program in stirred milling technology focusing on mill performance evaluation, model development and scale-up methodology. Industrial VTMs are being assessed using a consistent circuit survey protocol to evaluate the performance of VTMs in comminution circuits. The survey protocol includes identification and modification of sampling points, appropriate sampling techniques, controlled circuit stability, and best sample analysis practice. To initiate this study four surveys were conducted in the tertiary grind circuit in the Ridgeway Concentrator at Cadia Valley Operations (CVO) that treats the full circuit throughput of over 800 tph. To deal with the high feed rate the site opted to lead the world in the application of stirred mills by installing the largest VTM, at 3000 hp (2240kW) in closed circuit with a hydrocyclone bank. On average the operating work index was 13.1 kWh/t, reducing the secondary grind product by 40 - 50 ¦m to the required 80 to 100 ¦m range. The applied specific energy is relatively low in these low-intensity stirred media mills at 2.7 kWh/t. The size specific energy was 24.2 kWh/t-75¦m. Based on the survey and operating data the VTM circuit is performing well in this high-throughput tertiary grinding application, producing a sub-100¦m product.CITATION:Palaniandy, S, Powell, M, Hilden, M, Kermanshahi, K, Allen, J and Mwansa, S, 2013. VertiMill« - Development of circuit survey and performance evaluation protocols, in Proceedings MetPlant 2013 , pp 162-175 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By William D. Dodge

A typical quality program plan is presented for explosion-proof (XP) electrical enclosures. The plan is suggested for manufactures of XP enclosures which are to be certified by MSHA for mining use. The plan describes the quality system, organization and implementing mechanisms which are to be applied in the manufacture and delivery of certified XP enclosures. Example forms and example procedures are included.

Jan 1, 1984

In dealing with the pulverization and treatment of auriferous ores, it may be stated that there is not one system of treatment applicable to all classes. In the southern portion of New Zealand the ores generally contain free gold, with scarcely any impurity that is, it is found in an almost pure state, without any alloy, and its dissemination amongst the matrix is generally in tolerably coarse particles. The only difficulties the mill man has to contend with, are the economical concentration of pyrites, which in some of the lodes are rich in gold, and the extraction of the gold the pyrites contain. In some of the lodes there is what may be termed float gold, that is, the particles of the precious metal are so finely divided that it passes over the quicksilver tables, and, unless there are other appliances for saving it, this class of gold is entirely lost.Indeed it is only within the last five years that any attention has been given, in the southern portion of the colony, to saving the fine gold that has passed the amalgamating tables. In the North Island the ores are very complex there are scarcely two mines, although they may be adjoining each other, where the bullion is of the same character. On every field the gold is alloyed with silver&apos;, and in combination with other metals and mineral substances, such as copper, zinc, antimony, galenfl, iron, sulphur, arsenic, etc., and, in some instaaces, cinnabar, as in the case of the Champion lode at Tui Creek, Te Aroha. Ores of this class are extremly difficult to treat satisfactorily.

Jan 1, 1903

"Geoscan is used for multi-elemental analysis of conveyed bulk materials in the minerals industry with proven performance and demonstrated paybacks of weeks or months in iron ore, manganese, copper, zinc-lead and phosphate industries. Geoscan-M measures continuously through the full bed depth and is unaffected by belt speed, particle size, layering, mineralogy and dust levels. Increments of typically two minutes are accurately measured and provide the plant operators with tonnage weighted results of contained elements. Measurement of the composition in real time enables prompt feedback to the mining operators and also feed forward to the process operators. Crushed ore increments can be diverted based on composition, such as diverting waste for disposal or marginal material to a stockpile for separate processing. Bulk sorting allows material to be placed into relevant stockpiles for subsequent blending to achieve consistency for process feed. Parameters used for decisions may be primary metal content, deleterious component content, other process parameter, or a combination of these. Process parameter may be the elemental ratio between critical components, e.g. Cu:S ratio, basicity, or the content of an “indicator” element (such as Si indicating material hardness). Benefits will be discussed based on case studies in copper and iron ore.IntroductionAs operators of process plants strive to remain competitive as capital and operating costs increase and commodity prices fluctuate, more focus has been directed at incremental performance improvements at incremental cost rather than major expansions to increase output. The philosophy of working smarter allows plants to adopt technologies proven in other industry sectors to minimise risk. This paper discusses one such technology that the minerals sector is adopting and has found to be safe, reliable and accurate with paybacks of weeks in most applications. New applications continue to be found and major benefits realised at various stages in the processing and handling of ores and products."

Jan 1, 2016

By T. P. R. de Jong, H. Harbeck

"This contribution reports recent mineral sorting experience and lists the opportunities of the newest generation of automatic sorters with a special focus on electromagnetic detection and Xray transmission. With the available sensor resolutions and actuator systems that are available today sorting of minerals down to 2 mm size and up to 250 mm lump size is technically feasible. In industry, ore as well as coal is still hand-picked and current automation potential only utilised in a handful of specific applications. Recently a number of technological developments took place that may increase sorting potential, save mill costs and lead to lower overall tonnage costs.They are:??High speed and high resolution sorting systems based on X-ray transmission imaging??High speed on-line image processing and further development of advanced data processing??Modular multi-sensor automatic sorting units (using one or more sensors such as colour, electromagnetic and X-ray in a single device)??Sensitive electromagnetic sensors for sorting based on differences in magnetic susceptibility and electric conductivityThe above enables compact dry separation, insensitive for moisture fluctuations and at high separation sharpness, as well as “electronic” high gradient magnetic separation for larger particles. Besides conventional X-ray transmission (XRT), dual-energy XRT (DE-XRT) is now being redesigned to meet the requirements of the mining industry. The mentioned technologies provide automatic dry separation of minerals and rock as alternative for conventional processing."

Jan 1, 2005