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By Pierre J. Goossens

Since Guild 1 and Snelgrove 2 attracted our attention to the relationships between certain endogenic ore deposits and plate boundaries, an abundant flow of papers appeared in the metallogenic literature concerned with this problem and its application to mineral exploration. Some of the papers only speculate with the formation of specific type of ore deposit 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 Other papers are more concerned with genetic and structural relationships between plate tectonics and mineralization 13, 14, 15, 16, 17, 18, 19, 20 They are philosophical, in that they are generalized and refer to no specific area. Yet it is true that a large part of the world mineral potential is concentrated at the convergence of oceanic and continental plates, for example, around the Pacific. Therefore, the interaction of two plates by either subduction, obduction or slippage likely has an important role for the genesis and/or the (structural) control of these "orogenic" ore deposits. If subduction is the driving mechanism for the generation of igneous rocks 21, 22 and endogenic ore deposits 18, volcanic activity and the nature of volcanic products certainly are the major geologic processes and events to be tested. Fonteilles 23 and Alsac 24 have already emphasized the important relationship between mineralization and the talc-alkaline affinity of the volcanics. The Andean orogen is one of the best areas for testing such genetic relationships. Rich and varied endogenic and volcanogenic ore deposits occur there and plate interaction is still active.

Jan 1, 1975

By B. Anameric

Considerable effort has been directed towards understanding the carbothermic reduction mechanisms of self-reducing, fluxing dried green balls to produce pig iron nuggets. Given the geometry of the situation, some investigators believed that the shrinking core model was applicable. Hence, this study involved investigation of the applicability of the shrinking core model to pig iron nugget production. The experiments involved heat treatment of dried green balls utilizing either a laboratory-scale resistance box furnace or a gas-fired muffle furnace at various furnace temperatures and residence times. The products were analyzed for the following: (i) preferred reaction pattern, (ii) distribution of the metallized areas, (iii) % iron content variation in the pig iron nuggets from surface to center, (iv) carburization pattern and (v) physical and chemical properties of the pig iron nuggets. It was determined that the reduction of iron oxide occurred simultaneously throughout the sample and not beginning at the surface and propagating inward; thus the shrinking-core model was not applicable. Heat transfer and gas diffusion from surface to center were not the rate-limiting steps for reduction and carburization reactions.

Jan 1, 2011

By David M. Lapham

In Pennsylvania, 310 sampled sites of clay and shale have been evaluated for: potential use, chiefly as structural clay products, refractories, and lightweight aggregate; lithology; physical properties tests; fired tests, both quick-fire and rotary kiln; major-element chemical analyses, and quantitative five-component X-ray mineralogy for quartz, mica, feldspar, kaolinite, and chlorite-vermiculite-montmoril-lonite. Approximately 80 percent of the samples are of some potential use. Of 220 shale samples, 84 were potential lightweight aggregate sources and 83 potential brick sources. Binary correlations of test data versus potential use indicate that certain empirically determined parameters may be critical. These are: lithology, particularly for medium to super-duty refractories and lightweight aggregate; kaol-finite content for refractories versus low-temperature fired product sources; quartz content illustrating that there is an apparently necessary minimum quantity for brick; quartz content, which is low in high grades of lightweight aggregate; mica content, which is low for refractories and possibly high for lightweight aggregate; total iron, which is low for refractories and shows a 40 percent minimum for lightweight aggregate; carbon dioxide, which is low for refractorfes, beneficial in lightweight aggregate, and probably restrictive for some tiles choroite yermicalite, which is low for refractoies and possibly beneficial in lightweight aggregate. In Pennsylvania, clay and shale materials constitute one of the state's major economic mineral resources. To date, the testing program indicates considerable development potential in brick, tile, and lightweight aggregate industries, and perhaps a future potential for aluminum from shales that exceed 20 percent A12Q3.

Jan 1, 1971

By J. Marsden

Lift height, overall heap height and climate all play an important role in determining precious metals leaching rates, recoveries, operating costs and capital cost requirements for heap leaching operations. The effects of these factors are not easy to predict from testwork, and this can result in unexpected delays in metal production, lower recoveries than expected and higher capital and operating costs than necessary. This paper investigates the economic impact of lift height, overall heap height and climate on heap leaching and provides criteria to assist in the design and operation of leaching facilities. Descriptions of three heap leach operations in the western USA are provided to support the discussions and conclusions.

Jan 1, 1995

By Dirk van Zyl

Natural materials can be used successfully in the construction of heap leach pads. The use of these materials usually result in the least expensive approach for such facilities. Sufficient geotechnical experience has been gained in the design and construction of clay heap leach pads so that they can be used with confidence. A number of operators presently use clay pads in their heap leach facilities; these include Alligator Ridge, Ely, Nevada (gold), and Union Carbide, Gas Hills, Wyoming (uranium). This paper describes the construction and field investigation of a clay pad for the heap leaching of agglomerated precious tailings. The project is located in the Mojave Desert, Southern California. The design had to satisfy operational requirements as well as regulatory requirements. The California Water Quality Control Board (WQCB) was one of the agencies which had to issue a permit for the project. Their biggest concern was the discharge or escape of cyanide into the environment. Rather stringent requirements were therefore placed on the pad design criteria, especially in terms of permeability.

Jan 1, 1983

By Miguel Reyes, Chenming Zhou, MATTHEW GIRMAN

This paper is aimed at helping the mining industry to better understand the challenges posed by electromagnetic interference (EMI) and to promote electromagnetic compatibility (EMC) in underground coal mines. The paper begins with a review of EMI standards in other industries, then presents some representative examples of EMI instances that have occurred in the mining industry, followed by a literature review of published EMI research in mining and, finally, a discussion on mitigation strategies and practical considerations related to EMI in mining.

By J. K. Wolski

This paper addresses the effects of using jet fans as booster fans in mine ventilation networks. A method was developed to determine the pressure generated by jet fans using the momentum theory. The influence of a reduction cone and other ventilation parameters on the jet fan pressure was analyzed. Verification experiments conducted in the Waldo Mine are described. Examples are given to demonstrate the conditions for the effective use of jet fans.

Jan 1, 1998

By Jian Deng, Hehua Zhu, Lianyang Zhang

Rockburst is defined as a sudden and violent explosion of rock on the surface of a rock excavation. Rockburst has been regarded as the least understood and most feared hazard problem for underground rock excavations. Traditionally, rockbursts were classified into the strain, pillar, and fault-slip categories. However, rockbursts are also known to occur at stress levels well below the rock yield strength, in mines where the rock is far from brittle, or without the presence of geological discontinuities. A plausible explanation of rockbursts is buckling, which has been identified as one of the main mechanisms for rockbursts. It is observed that rockbursts are often induced by dynamic loadings (pulses) from adjacent blasting. Therefore, the present paper studies the effect of pulse shape and amplitude on pillar rockbursts induced by dynamic loadings from blasting using the method of numerical analysis. The governing equation of a pillar’s motion is set up and the mechanism of pillar rockbursts is investigated through a practical example. The results show that it is not the shape of a pulse but the impact energy to decide the occurrence of pillar rockbursts. If all other parameters remain the same, pillar rockbursts are more likely to occur when the pulse duration is longer. The parametric resonance and the perturbation of dynamic loadings are also found to play an important role in the occurrence of rockbursts. These insights would provide invaluable clues about the mechanism and for better control of pillar rockbursts.

Apr 26, 2022

By L. C. Morales

During my College days in Mexico City, my Mineralogy Professor used to say "Mexico is the Horn of Plenty, rich in minerals, and it is easier to say which minerals are not found instead of stating all that exist. He said that the only ones missing are bauxite, diamonds and titanium ores." Today, twenty years later, a rutile mine in Oaxaca is in successful operation. Mexico has an area of approximately two million square kilometers, with volcanic activity, large shores and mountainous areas reaching as high as 6,000 meters above sea level. These conditions are favourable for most mineral deposits, some -of commercial value and others as a source of mineral samples only. (fig. No.1) In addition to vast mineral wealth, Mexico has -another valuable asset in .his people. Even before the discovery of America, natives were successfully mining metals, and during the Colonial --days, the mineral deposits were mined to increase the wealth of Spain, and it increased the --knowledge of mining. All this experience was passed along from generation to generation, and created a tradition of mining and minerals processing engineers, that currently account for approximately 182,000 persons supported by mining related activities.

Jan 1, 1994

By Russell J. Sheets

Reactivation of highwall slope failures during adverse weather had intermittently impacted haul road access into a previously mined open pit. These impacts ranged from limited access to full closures; however, the greater impact was to an underground mine that was developed within the open pit. Following several significant precipitation events, a rapid snow melts greatly accelerated movements finally closing the haul road and destabilizing other past failures. In addition to re-designing the overall pit access, the decision was made to relocate the primary portal to a more stable highwall. An accelerated surface geotechnical review was required to advance the portal relocation; however, only existing information from past investigation, existing geology model, visual inspections, and slope monitoring data were available for the assessment - no new investigations or data collection could be completed within the allowable timeframe. The evaluation included a review of the geology, an assessment of the current highwall condition and previously observed performance, and a rockfall analysis to evaluate existing catchment above the proposed new portal location.

Feb 1, 2024

By Neely H. Bostick

The primary and secondary organic matter in sedimentary rocks changes markedly when it becomes heated as a consequence of thick sediment accumulation and normal geothermal gradients, high geothermal gradients, hydrothermal fluids, or igneous events. Contact zones adjacent to small igneous dikes allow sampling of a single sedimentary bed that has been exposed to temperatures in a range as great as 30-500°C. Dike-heated rocks are, therefore, good sites for research on thermal effects because variation of the original organic matter is minimal, the range of heating is great, and the history of rock heating in a dike zone is relatively well established. In rare cases, such as at the dike near Wolcott, Colorado, described in this paper, the rock samples are sufficiently unweathered to allow analysis of secondary bitumens generated by the heating. We show by optical microscopy, scanning and transmission electron microscopy, and geochemistry the kinds of solid organic constituents in sedimen¬tary rocks and in ore deposits and the effects of heating. The primary phytoclasts that make up kerogen In sedimentary rock and in some ore deposits (pollen, resin, charcoal, humified woody remains, etc.) change in ways that are familiar to coal specialists. Progressive loss of moisture and other volatile matter yields residual kerogen that Is relatively higher in carbon and lower In oxygen and hydrogen, and has greater molecular or polymer ordering. In our contact zone examples, atomic H/C ratios of kerogen decrease from 0.8 (one case from 1.4) to 0.4, the hydrogen index from Rock-Eval pyrolysis decreases from 70 to 5, and the transformation ratio from Rock-Eval pyrolysis increases from 0.06 to 0.5 with increased heating. The visible effects of heating seen by scanning electron microscopy and light microscopy include formation of vesicles and flow structure, the development of optical anisotropy and mesophase, change of color, and increase in the refractive index, absorption, and reflectance. Some of these changes In primary organic matter are observed also in secondary organic matter, for example, in solid bitumens in sedimentary gold ores or In lead-zinc deposits. Quantification of color or absorption changes is difficult because it Is hard to make thin sections of organic matter with uniform thickness. However, natural objects with uniform thickness can be used. We show the colors of pollen In rocks from the Salton geothermal field at temperatures ranging from 100 to 300°C, and of pollen heated in laboratory bombs from 150 to 400°C. Measurement of vitrinite reflectance is a practical way to quantify thermal changes of kerogen and minerals of most sedimentary rocks because vitrinite is fairly widespread In sedimentary rocks of Devonian age and younger. For example, the reflectance of vitrinite rises from the regional level, as low as 0.4 % Ro, to more than 5% Ro adjacent to dikes that cut sedimentary rock. This is equivalent to the rank change from subbituminous coal to extreme meta-anthracite. The rise is most abrupt near thin dikes, but when the distance from the igneous contact is expressed as a ratio of dike thickness the reflectance rise is similar for all dikes. Controlled heating of vitrinite-bearing rocks In the laboratory provides a means to assign known temperatures to vitrinite-reflectance values. The derived plots of temperature In dike contact zones have the same shape and level as those predicted by heat theory, and the temperature lines extend toward dike contact temperatures that are about half those of most magmas, as expected if the intrusions did not flow past the sedimentary rock for a long time. The globular submicroscopic structure of vitrinite and Its heterogeneity, which we show by means of transmission electron microscopy, pose some problems In selecting a uniform type of vitrinite for measurement of thermal changes. At present, routine reflectance values of vitrinite dispersed in rocks have a relative uncertainty as great as 10%. Thermally caused chemical changes in the primary kerogen, especially decrease in the oxygen and hydrogen contents, lead to formation of secondary products in the contact zone. The measured changes of secondary organic products in these rocks include formation of peaks In concentration of total extractable organic matter and in hydrocarbons, and in the saturated/aromatic hydrocarbon ratio over the interval where primary organic hydrogen decreases most rapidly--then destruction or expulsion of these products at high temperatures. The odd carbon-number predominance of the C25-C31 n-alkanes In samples far from the dike disappears by about 1.3% Ro whereas the 13C: 12C ratios of the saturated and aromatic hydrocarbons increase over most of the thermal range. The saturated aromatic hydrocarbon ratio at first increases, corresponding to thermal generation of saturated hydrocarbons, then decreases in the most altered samples. One use of organic petrography, in addition to identifying organic fades or thermal alteration, is recognition of sample contamination such as the solid organic additives used in some drilling muds which may contaminate geochemical samples.

Jan 1, 2013

By P. D. Pattillo, J. B. Cheatham, Y. -H. Lin

The stability of a hemispherical cavity, intended to model a perforation opening in the vicinity of a borehole, is analyzed for the case of poroelastic-plastic material behavior. Two plasticity models of differing complexity are considered, with the emphasis in either model being the use of strain softening to calculate inelastic stiffness. Sample results illustrate the effect of steady fluid flow on the response, and possible collapse, of the near perforation region.

Jan 1, 1986

By K. N. Han, P. B. Queneau, A. Stojsic, M. J. Collins, V. J. Ketcham, R. M. G. S. Berezowsky, W. D. Vardill

The bulk of the ore found in the Lihir Island deposit is refractory in nature, with the gold contained in auriferous pyrite. In support of an evaluation of the development of this deposit by Kennecott (a wholly owned subsidiary of RTZ) and Niugini Mining Ltd., testwork has been carried out at the Sherritt Research Centre to demonstrate the amenability of the Lihir ore to pressure oxidation pretreatment to liberate the refractory gold. The results of pilot plant treatment of the Lihir ore in a continuous circuit with a feed rate of between 10 and 30 kg/h ore are described. The integrated circuit comprised pressure oxidation, residue washing, and gold recovery from the washed residue by carbon in leach or carbon in pulp cyanide leaching. Significant factors affecting gold recovery included temperature and retention time in the pressure oxidation step, and the concentration of soluble chloride in the feed. Gold extraction from well washed ore, after oxidation at 210°C for 66 minutes in the autoclave, was typically between 94 and 96%, compared with less than 30% by direct cyanidation.

Jan 1, 1993

By Donald P. Schlick

Gentlemen, today I would like to talk to you about metal and nonmetal mine health and safety--past, present and future. Briefly, I will comment on the past because it is important to an understanding of our present activity and our plans for the future. Federal inspection of noncoal mines was not authorized until 1966, when congress passed the federal metal and nonmetal mine health and safety act; public law 89-577, with the passage of this act, the federal inspector, for the first time, had the delegated authority and responsibility to enforce health and safety regulations designed to prevent personal injuries and occupational diseases, the new law also provided for the education and training of our miners; assistance to the operator through the transmission of technical and scientific information and assistance and equally important, the law made provision for state participation in the congressional mandate to prevent injuries and save lives in the mineral industry, Before I tell you about our program and our future plans, I want you to know that I am here to listen as well as to talk! In my view, the only kind of communication that is meaningful is two-way communication. Our nationwide progress in metal and nonmetal mine health and safety during 1972 cannot be measured in reduced fatalities or injuries. The unforeseen tragedy that took pace in Kellogg, Idaho, in may of last year mode that almost a certainty.

Jan 1, 1973

Since 1992 the Grasberg Mine, located in the remote regions of Indonesia, has utilized the Modular Mining System. Over the last several years, major steps have been taken to maximize this productivity enhancement system. These steps include; the Automated Lineup, the Linear Program upgrade, tracking of Mean Time Between Failure, a MEDS system interface, a VMIS system interface, and implementation of the new Graphical Operator Interface Console with Global Positioning, This application of new technology and innovation has lead to improved performance, understanding and reporting, as well as the quality of the Indonesian Engineers. These efforts have contributed 10 Grasberg achieving one of the lowest mining costs in the copper industry.

Jan 1, 1998

By Lianhui Jia, Yali Han

"The key technologies of a large rectangular pipe jacking machine with dimensions of 10.12m × 7.27m (width x height) include selection of rectangular cross-section cutting modes, analysis on the strength and stiffness of the rectangular shield, integrated control of electro-hydraulic proportional thrust systems and ground conditioning for excavation are presented in detail in this paper. These key technologies have been successfully applied and verified on site during tunneling, providing a new concept for the building of large rectangular traffic and pedestrian tunnels in urban areas for the future.1 INTRODUCTIONIn the past, underground tunnels were mainly used for drainage, sewage, utilities, metro tunnel, etc. and most of them had circular cross-sections. Recently, as a result of economic development, gradually accelerating urbanization process and diminishing ground space, underground tunnels have already become a new trend for urban underground space utilization. Due to the heavy traffic flow, the demands for rectangular cross-section underground tunnels, such as pedestrian underpass and road tunnel, are increasing gradually.The Rectangular pipe jacking machine (hereinafter referred to as RPJM) was firstly developed in Japan for the construction of metro station, pedestrian underpass, underwater tunnel by-passes, etc. Kazunaki Kawai et al. introduced a RPJM developed and manufactured by KOMATSU in 2002 [1]. Tosikazu Kubota et al. confirmed the rectangular tunnels’ superiority to circular tunnels with regard to larger inner cross-section and lower construction cost in their RPJM construction reports [2]. Compared to circular pipe jacking machines, a RPJM also has the merits of a higher inner tunnel space utilization ratio and is able to excavate in shallow overburden areas. As shown in Figure 1, the effective area of a rectangular tunnel is more than 20% higher than that of an equivalent circular tunnel."

Jan 1, 2016

By R. R. Guzman

In this study, the "Mine Project Risk Management" methodology, MPRM (Botin et al. 2011), has been applied to characterize the sources of uncertainty and to quantify risk in the mining engineering stages of Block Caving mining method. As the result, rock mass caveability and ore fragmentation were identified as the two most relevant parameters of this process and a methodological model has been developed to quantify the risk associated to each of these two parameters. Furthermore, the applicability of the proposed model has been validated using as a case study the Chuquicamata Underground Mine Project in Chile.

Feb 23, 2014

By R. W. Amstutz

Abstract. The shaft was drilled on U.S. Government land in the Piceance Creek Basin and was funded by the U.S. Bureau of Mines. It was drilled to 723 meters (2 371') to provide access to rich deposits of oil shale, nahcolite and dawsonite for geotechnical test work and environmental mining research. Rotary drilling and dual string, reverse-air, jet-assist circulation methods were used. Drilling required 8 months. Site preparation, running and cementing the casing required another 4 months. A 2.44-meter (96-inch) ID steel welded casing, 5.1 cm (2 inches) thick was installed and 2 700 tonnes (63 000 sacks) of cement were slurried and pumped into the annulus.

Jan 1, 1980

By Abbas Zaidi, Betty L. W. Ou

Wastewaters generated during the extraction of gold from the ore can contain a variety of contaminants such as cyanide, heavy metals and arsenic. Proper management of these wastewaters is therefore necessary to minimize the negative impact of gold mining and milling operations on the environment. The Wastewater Technology Centre (WTC),located in Burlington, Ontario, Canada, has been involved in several studies related to the evaluation of various effluent treatment technologies which are relevant to the treatment and proper management of gold mill effluents. These studies have included bench and pilot scale tests, and the evaluation offull-scale systems. Furthermore, the WTC staff developed protocols for cyanide analysis in gold mill effluents, and a mathematical model for predicting the degradation of cyanide in tailings ponds. The information generated by the WTC staff has been referenced in several reports and papers published over the last ten years (Schmidt et.al. 1982, Simovic & Snodgrass 1989, Whittle et.al. 1989, Zaidi et.al. 1989, Zaidi et.al. 1991). Recently, the WTC has started to develop a micro­computer based expert system for use by decision makers in the gold mining industry and relevant government agencies who are involved in process design, process evaluation, costing, evaluation of the best practicable technology, approval of suggested effluent management systems, and so on. This paper presents some relevant background information and a discussion of the latest version of the expert system being developed by the WTC.

Jan 1, 1992

By P. R. Hervey, J. W. Foise

Quartz is the second most widely used electronic material, with approximately 3,000 t (3,300 st) of single crystals used each year. Most of the quartz used in electronics is synthetic and is manufactured using a technique called hydrothermal growth. This paper reviews the basics of hydrothermal growth, the feedstocks used for these crystals and the challenges to improving the growth process. This paper also reviews the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 2002