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By Roland Froidevaux

The potential use of geostatistics for quantitative ore reserve reporting is shown using a simple gold case study as an example. The need of defining quantitative class limits is stressed, and a possible approach to this problem is suggested.

Jan 1, 1983

By S. C. Tadolini

Roof support systems have evolved from standing posts and timbers to a generation termed ?big nails? where steel bars are inserted into boreholes and anchored with expansion shells and/or resin cartridges. These systems have been effective but are limited to mining height. Additionally, the properties of steel do not resists shear forces or have the flexibility being required in difficult ground conditions. The next generation of roof support systems is coupling the best parts of the ?big nail? and resin grouted cable bolt systems. This paper will present the advanced technical solutions of the next generation of cable systems that includes an indented high-capacity PC-strand used with a variety of fixtures. Case histories of support applications will be presented.

Jan 1, 2012

By J. D. Lowell, L. Quevedo

I will talk today about a porphyry copper exploration program now underway in the Amazon jungle in the southeastern part of Ecuador near the border with Peru. The project is unusual for two reasons: first the deposits are of Jurassic age, 153 m.y.o., which is unusually old for porphyry copper deposits and they may be the most significant pre-Tertiary age porphyry deposits known. Second, the district was found only six years ago which makes this the most recent discovery of a totally new porphyry copper district. The new porphyry district, known as the Zamora River Copper Belt, or the Corriente Copper Belt, is a north trending area 50 km long by 10-15 km wide, which is nearly aligned with the axis of the Jurassic age Zamora batholith and with the course of the Zamora river. Gencor in 1994 initiated a regional grassroots gold exploration program based on reconnaissance geologic mapping and geochem sampling which did not find a gold mine, but which identified the San Carlos porphyry copper system in April, 1995. In a later reorganization between Gencore and Billiton the Ecuador project was transferred to Billiton and between the Gencore work and Billiton’s a total of 10 porphyry copper systems were found over the next four years. In the period of 1997 - 1999 Billiton drilled a total of 11,000 meters of wide spaced core holes in the San Carlos, Panantza and Kutukus prospects. In October 1999 Billiton concluded a farm-out, joint venture agreement with Corriente Resources and Lowell Mineral Exploration for additional exploration of the Zamora property. This is funded by Corriente and managed by Lowell Mineral Exploration and a total of 28,000 m of core drilling was completed through August 2001. An immediate result of the Corriente Lowell project was the discovery of potentially commercial ore reserves in two new deposits at Mirador and Warintza. Additional closer spaced drilling was done in the Panantza deposit and additional drilling is planned at San Carlos, in targets related to Warintza, and elsewhere.

Jan 1, 2002

By I. S. Parrish, D. W. Kappes, G. G. Austin

Micron-sized gold disseminated in lower Cambrian siltstone has been found at the Sterling mine near Beatty, NV. A shoestring-shaped body has been developed by central and fringe drifts and is being mined via a modified retreat room and pillar system. The siliceous ore crushed to 5.08 cm (2 in ) is stacked to 4.6 m (15 ft) over a layered sand, gravel, and impervious PVC base. Gold is leached using a 0.1% cyanide solution and deposited on activated coconut shell carbon. Stripping of the carbon by hot solutions of 1% NaOH and 20% Ethanol yields overall recovery of about 75% of the fire assay head.

Jan 1, 1983

By Maria C. Jaime

Optimization of the rock cutting performance plays a major role in the tunneling operation. For a given set of tool and cutting environment, rock fragments may be chipped away in numerous manners and it is crucial to understand and be able to predict the dynamics at the cutter-rock interface. This paper presents rational and realistic 3D finite element modeling of rock cutting where typical computational issues ?such as contact formulation, appropriate rock material response, mesh distortion, and crack propagation? are overcome. Cutting forces and failure mechanisms in this finite element analysis are successfully validated by laboratory single-cutter scratching tests in sandstone.

Jan 1, 2010

By Joel Nonnweiler, David Young, John Hawley

The Sacramento Regional County Sanitation District has implemented a billion-dollar interceptor system master plan, including the 31 km (19 mile) long Lower Northwest Interceptor (LNWI). For the two LNWI Sacramento River crossings, pipe-jack/micro tunnel drives in excess of 300 meters (1,000 ft) from 30 meter (100 ft) deep shafts in mixed soil conditions below the water table were considered, as were600 meter (2,000 ft) tunnel drives utilizing pressurized-face tunnel boring machines. Operation and maintenance concerns, predicted flood scour, and levee concerns are discussed. A risk assessment process was used to select both profile and construction method. Construction will begin in mid 2004.

Jan 1, 2003

By R. J. Baumgartner

Sustainability issues are from rising interest and importance for the mineral industry worldwide. In order to bring them into management processes and to improve decision processes, economic, ecological and social aspects of products, services or technologies have to be assessed. In this paper, the concept of integrated sustainability assessment is presented. Each aspect is assessed with quantitative or qualitative methods. The results of these ecological, social and economic sub-assessments are integrated by the means of Fuzzy Logic in order to regard preferences of decision maker and circumstances of decision situation. An example demonstrates the application of this new instrument.

Jan 1, 2005

By Richard D. Christie, K. Jay Pillai

In the past, it was not unusual for coal preparation plants to discard fine run-of-mine coal. This practice has changed due to increasing quantities of fine material, improvements in beneficiation methods, and the need to recover revenue from these fines. It is in this context that the coal industry has increasingly been turning to froth flotation for fine coal beneficiation. Reagent schemes have been developed to promote coal flotation and to treat the resulting refuse material. While reagent technology has improved, however, most plants rely on manual control of reagent dosing and circuit operation. This often results in misuse of reagents, loss of coal recovery, and consequent loss of revenue. Fine coal circuit operations can be dramatically improved through automation. Intelligent process control systems are now in use which are capable of optimizing reagent usage, maximizing coal recovery, and minimizing chemical costs associated with refuse handling. This paper describes a type of control system currently used in preparation plants, and provides data and information on the significant improvements such systems can produce.

Jan 1, 1994

By Don C. White

Santa Rosa is a mid-Tertiary, volcanic-hosted, gold-silver deposit. Current proven and probable reserves are 8.9 Mt (9.8 million st) grading 1.5 g/t (0.044 oz/ st) gold, minable by open pit and amenable to heap leaching. It is the product of hydrothermal mineralization along an arcuate segment of a caldera collapse ring fault in a probable maar volcanic setting. This segment was later broken by radial faults. Gold at Santa Rosa occurs principally as electrum, finely disseminated through intermediate tuffs, and associated with pyrite. The nearby Alto de la Mina deposit displays stockwork silica-pyrite-gold in a tectonically and hydrothermally shattered andesite flow. Miocene epithermal mineralization was accompanied by central silicification and pyritization and more distal argillization. An andesite flow cap rock at Santa Rosa played a pivotal role as an upward permeability barrier. Highest gold grades and most intense alteration occur closest to the ring faults and immediately beneath the andesite flow. Supergene alteration effects on the gold distribution are minimal.

Jan 1, 1995

By Ferdi Camisani

The ‘Bible’ 1977 & 1981 ‘South African Mine Valuation’ by C. D. Storrar. Proved reserve (=’measured ore’ USA; ore reserve = the payable portion of the proved reserve) -Fully developed (…immediately available…) -Partly developed (…not immediately available…) -Undeveloped (…unavailable…) Probable reserve (=’indicated ore’ USA) Possible reserve (=’inferred ore’ USA) Life-of-mine reserve (Proved + Probable + Possible)

Jan 1, 2003

By Paul G. Schmidt

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

Jan 1, 1978

By A. Kaczmarek

As the mining industry is enjoying a much needed and long awaited increase in demand for natural resources, consolidations in both the mining and mining service industries and a generational departure of experienced industry professionals is challenging today’s mining companies, not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies, oftentimes lacking in operating properties to draw from for experienced professionals and having to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This paper discusses some strategies developed by Anatolia Minerals Development Limited in developing its Çöpler Gold Project in central Turkey.

Jan 1, 2006

By J. K. Neathery, T. X. Li, H. Ban, J. L. Schaefer, J. M. Stencel, X. K. Jiang

Pneumatic, triboelectrostatic processing of physical mixtures containing fine (-200 mesh) particulate may have significant application potential in the mining and energy industries. Such dry processing methods, especially for finely comminuted materials, have not been examined in as much detail as wet processing methods nor have been part of the training or education of mining and process engineers. We have examined fundamental and applied physical and engineering factors controlling triboelectrostatic beneficiation of fine-sized physical mixtures, one of which - combustion fly ash - has size, heterogeneity and mineral concentrations typical of those expected in mined minerals. The applicability of dry processing, however, cannot be readily evaluated because of the unavailability of standard procedures for process assessment.

Jan 1, 1999

By Susan G. Bilhorn

A number of studies have been conducted in active and inactive mine environments using continuous monitoring and data acquisition systems to detect various parameters. In addition to the information obtained for research purposes, these monitoring systems can provide a means to remotely collect required information (such as radon daughter concentrations and air velocity) and control various conditions (such as fan operation and air door position) in numerous working sections of an active mine. Selection of detector locations and placement, which are critical to obtain the information and control desired while not inhibiting mine operations and influencing the detector readings, are covered in this paper.

Jan 1, 1984

By N. Aouad

Dump truck operators are exposed to whole-body vibration (WBV) levels that exceed the International Standard Organization (ISO) 2631-1. The WBV level measured by RMS acceleration value, for operator comfort, and long-term health and safety is under 0.315 m/s2 by these standards. However, fundamental research by Frimpong and Aouad (2009, 2012) and field experimental study by Kumar (1999) have shown that operators are exposed to extreme WBV levels exposing them to injuries and musculoskeletal diseases in the long-term. These extreme WBV values in the vertical direction are equal to 3.56 m/s2, 1.12 m/s2 and 0.87 m/s2 for the operator?s seat, lower-back and cervical regions, respectively. This paper will outline current research to solve these problems. Keywords: WBV, Truck Vibrations, MSC.ADAMS, Virtual Prototyping

Feb 27, 2013

By E. Steiakakis, A. Athousaki

Nowadays, stakeholders have a strong say to the enforcement of best practices by mining and quarrying companies. In most cases there is a direct relationship between sustainable development principles and best practices. Mining companies try to apply best practices in order to sustain their operation without lost time and effort to litigation, and other obstacles. However, when and where there is a lack of state or regional mineral policy, or when the mineral policy is fragmented and touching on conflicting laws, mining operations may be subject to additional administrative hassles, and, thus, operators feel threatened and tend to apply best practices loosely. This paper argues that the only way that mining and minerals operations can be a source of development is to ensure that they are working within the framework of sustainable development. Furthermore, in order to follow the paradigm of sustainable development they would need to be guided by a regional, national or even transnational (i.e. European) minerals policy.

Jan 1, 2011

By Keith Bowers, Frank Mimnagh, Eddie Woods

The CTRL London Tunnels The Channel Tunnel Rail Link (CTRL) London Tunnels comprise 36km of internal diameter bores that were driven by Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs). The tunnels were constructed between the autumn of 2002 and the spring of 2004. The permanent works also included the 1.1 km long station box at Stratford, five ventilation shafts of depths between 30 and 54 m, 29 cross passages and various large diameter sprayed concrete lined connecting tunnels. The tunnels were driven under densely populated areas of north and east London, as depicted in Figures 1 to 4. Under the parliamentary CTRL Act the project had obligations to make

Jan 1, 2005

By Michael R. King

The application and use of steel fibre reinforced concrete in precast tunnel lining design is a growing trend due to its advantages in performance over plain concrete, and ease of manufacture compared to traditionally reinforced concrete. However, the design process and performance characteristics of the material are poorly served by current codes and standards. This paper provides some basic design guidance for segmental linings, and compares the material properties for the different material options. A typical example is considered to compare the possible results of lining arrangement and thicknesses for a plain, reinforced, and fibre reinforced design solution.

Jan 1, 2005

By K. Hanson

When done properly, benchmarking is an extremely effective tool for assessing ones performance, finding areas for improvement, and identifying strengths. However, when done improperly it can be an exercise in futility and result in incorrect observations and conclusions. A primary pitfall of benchmarking is collecting too much unreliable information. Surprisingly, the evolution of data storage and the ease of data collection are not helping with better data collection. Instead, it is just allowing one to collect more information, while at the same time inundating one with too much data. Additionally, the process of data collection can be tedious and is often times delegated to the least experienced individual resulting in unreliable and incorrect data collection and entry. Another primary pitfall of benchmarking is metrics that are cost based or poorly designed. Cost based metrics typically involve comparing unit mining costs ($/tonne). Between mines, unit mining costs are not very well correlated and have become further complicated by significant regional cost variations and mining inflation in the last years. Likewise, poorly designed metrics lead to poor benchmarking results. Examples of poorly defined metrics include: metrics that rely on information that is difficult to collect, metrics that are poorly defined, metrics which are too site focused, and metrics that measure low consequence practices.

Jan 1, 2011

By N. F. Sather

Results of comprehensive trace element analyses of samples of Illinois #5 and #6 seam coals and the unquenched ashes obtained from gasification of these coals in a Lurgi reactor are reported and discussed. Areas where additional background information is needed for assessment of the environmental impact of trace element emissions from coal gasification are identified.

Jan 1, 1976