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By Y. X. Tong

The simplicity off Ø=0 analysis has been taken advantage of to evaluate the geotech­nical problems of open caissons, slurry trench walls and piles in Shanghai. Undrained shear strengths obtained by various testing methods are correlated with case record and experimental data. Some problems posed by the construction of tall buildings are briefly discussed. Comments on applications are made to help engineers deal with practical problems.

Jan 1, 2010

Predicting Flotation Response from Liberation Information

Sep 13, 2010

By K. P. Kavun, M. N. Denisov

Discussed in the paper is the redesigned reserve/resource classification for solid minerals being put forth by the authors to replace the acting Russian classification of 19961. The new version is based on the traditional foundations of former Russian classifications and the principles of the ‘McKelvey box’, both categorizing mineral resources according to the degree of geological assurance and economic viability. Based on these approaches the classification deliberately deals with both reserve and resource categories very similar to those established by the Geneva Accords in terms of definitions implied. The authors proceed from the UN-ECE proposed concept of ‘reserves’ being a part of ‘total resources’ explored in great detail by geological and feasibility studies and economically mineable at the time of reporting. The draft classification distinguishes ‘proved’, ‘probable’ and ‘possible’ categories of reserves depending on the stage of feasibility assessment carried out, i.e. the degree of detail and accuracy with which modifying factors affecting mineability of an orebody are taken into account. The reserves are regarded as a product of feasibility assessment of ‘measured’, ‘indicated’ and ‘inferred’ resources. The portions of them not having been classified as ‘reserves’ are regarded as composed of two classes: ‘subeconomic’ and ‘potentially economic’ resources (or ‘resource base’). All the cells of the classification matrix are provided with traditional for Russia alphanumeric designations and appropriate UNFC codes. The classification scheme recommended is viewed as a step forward in improvement of the State inventory and reporting mineral resources in market conditions, conducive to cross-border professional collaboration in the field of providing reliable information on the mineral rawmaterials base of the world’s economy. Besides, it recommends an easy way to get rid of amethodological error in the UNFC classification scheme where consecutive stages of geologicalexploration are identified with a single inherent degree of geological assurance. Keywords: mineral resources, mineral reserves, classification, geological assurance, feasibility studies, subeconomic resources, undiscovered resources, competent person.

Jan 1, 2003

By Maurice Hunter

The paper outlines recent design developments in the computerization of surface crawler drills for the quarry industry. It references the technology firstly developed for the underground mining and construction industry, where automation and computerization has been in demand for a number of years.

Jan 1, 2003

By A. J. Rigby

Refractory linings in converters or anode furnaces used to over-oxidize the blister copper will suffer rapid deterioration, due to prolonged contact with copper oxide-rich slag. Nitrogen stirring with COP KIN porous plugs and use of SEMTECH OPC in converters and anode refining vessels can considerably reduce both refractory wear and processing times. In addition, careful control of the vessel atmosphere and the use of real-time optical process control minimize both slag volume and contact time with the vessel refractory.

Jan 1, 2005

By Lawrence Pelham

Introduction Fluorspar demand or consumption has been taken for granted in recent years, except for those that produce, market, or consume the commodity. Thinking used to be that as the steel and aluminum industry goes, so goes fluorspar. This is much less true today. The industry is becoming more dependent on chemical industries that feed primarily off hydrofluoric acid (HF) production. The US Bureau of Mines (USBM) published an assessment of world fluorspar reserves and resources. It created a foundation of valuable data that can be used to monitor fluorspar availability. Celebrations were held this year commemorating the 100th anniversary of the isolation of fluorine. The US and other countries continue to struggle with the controversy of ozone depletion and the effect of fluorocarbons on the atmosphere. Goals for the government's strategic stockpile are being reevaluated. The market for fluorine chemicals is changing and diversifying, making it a challenge to assess and forecast fluorspar/fluorine demand. US production and distribution Fluorspar Fluorspar shipments from US mines reached an all-time high near the end of World War II in 1944 at 375 kt (413,800 st). Eighty-two mines produced more than 453 t (500 st) each, and 10 mines produced more than 9 kt (10,000 st.) each. Illinois supplied 43% of total shipments. Consumption in 1944 was 372 kt (410,200 st), of which 56% was used by steel producers and 32% by HF producers. This was the last year that US production exceeded US consumption. The post-World War II record for fluorspar shipments occurred in 1951 at 315 kt (347,000 st) 58 mines produced more than 453 t (500 st) and eight mines produced more than 9 kt (10,000 st).

Jan 11, 1986

By Bassam Kattaa

"Abstract - A heavy mineral survey of beach and dune sands including geochemical analysis for trace elements was undertaken to evaluate the economic potential of the sands and to understand the nature and distribution of the heavy minerals relative to potential source rocks. Results indicate that heavy minerals are generally derived from outcropping volcanic rocks that comprise a proportion of the hinterland in the south part of our survey area. The most abundant minerals are magnetite and pyroxene. The morphologies of the heavy mineral grains are angular to subangular, suggesting that they were transported short distances from the source rocks. Factors controlling heavy mineral distributions include wave and wind action, proximity to provenance, the fluvial drainage network, and longshore currrents.The most economically important mineral is ilmenite. Zircon and rutile concentrations are relatively minor and thus have lower economic potential."

Jan 1, 2002

By J. Nielen van der Merwe

Rock engineering research and technology development in South Africa only received serious attention in reaction to the Coalbrook disaster in 1960. At the time, a number of gaps in knowledge of rock related matters were identified and in the ensuing years, these were progressively attended to. The paper describes the events that led up to the Coalbrook disaster and reviews the developments that took place afterwards. The effectiveness of the research outcomes are tested by referring back to the disaster. It is concluded that tremendous advances were made but that not all the unknowns were attended to at the same level. The strength of nominally square internal pillars is the one issue that received the most attention, but the strength of barrier pillars, overburden behaviour and loading systems are still largely unknown. Due to the complexity of the remaining unknowns, they can and should be addressed by the application of back calibrated numerical models. There are no readily available simple analytical solutions. The state of mining rock engineering research in South Africa borders on an emergency. More than a 1000 years of aggregate research experience has been lost in the last three years and funding is under severe pressure. There are disturbing parallels between the current positioning of the industry as a whole and the Coalbrook mine in the years preceding the disaster.

Jan 1, 2006

By J. Gómez-Hernández, P. K. Kaiser

Abstract The process of stress-induced fracturing around underground excavations in brittle rock is associated with dilation or volume increase of the failed, fractured rock. Different attempts to account analytically for this dilation have been made within the framework of plasticity theory. This theory has been developed mostly for metals, strain-hardening materials or soils, but brittle failure of rock-like materials is characterized by strain-softening behaviour and the volume change is dominated by geometric factors, which may violate stability principles of plasticity. In this work a semi-empirical Rock Mass Bulking Model (RMBM) was developed, using as starting concepts: dilation angle, plastic strain rates, effective deformation modulus, effective Poisson's ratio, Griffith locus, and the definition of a bulking factor BF introduced by Kaiser et al. (1996). The model was calibrated in order to obtain bulking factors that are consistent with experimental data and case studies of measured bulking around underground excavations. Résumé La fracturation provoquée par le stress autour des excavations souterraines dans le minéral friable est associée à la dilatation ou à l’augmentation du volume de la roche en rupture. Dans le cadre de la théorie de la plasticité, différents essais ont été faits dans le but de trouver une justification analytique pour cette dilatation. Cette théorie a d’abord été élaborée pour les métaux, les matériaux ou les sols d’écrouissage, mais la rupture fragile de matériaux d’aspect rocheux est caractérisée par un comportement d’amollissement et le changement de volume est dominé par des facteurs géométriques, ce qui pourrait ne pas être conforme aux principes de stabilité de la plasticité. Dans le présent ouvrage, un Modèle semi-empirique de masse rocheuse a été élaboré, dont les concepts initiaux sont les suivants : angle de dilatation, vitesse de fluage plastique, module effectif de déformation, coefficient effectif de Poisson, locus de Griffith, et la définition d’un facteur de foisonnement FF apportée par Kaiser et al. (1996). Le modèle a été calibré afin d’obtenir des facteurs de foisonnement qui soient conformes aux données expérimentales et aux études de cas sur le foisonnement mesuré autour des excavations souterraines. Kurzfassung Der Prozess von Brüchen in unterirdischen Abgrabungen in sprödem Gestein ist mit der Ausweitung oder der Volumenzunahme des gebrochenen Gesteins verbunden. Verschiedene Versuche im Rahmen der Verformbarkeitstheorie haben versucht, diese Ausweitung analytisch festzustellen. Die Verformbarkeitstheorie wurde hauptsächlich für Metalle, kalthärtende Werkstoffe oder Böden entwickelt, da sprödes Versagen von Gestein ähnlichen Werkstoffen von kaltenhärtendem Materialverhalten gekennzeichtnet ist, und die Volumenveränderung von geometrischen Faktoren beherrscht wird, die die Stabilitätsprinzipien der Plastizität übertreten. In dieser Arbeit wurde ein halbempirisches Rock Mass Bulking Model (RMBM) (Modell für das Aufgehen der Gesteinsmasse), entwickelt, für das die folgenden Anfangsprinzipien benutzt wurden: Ausweitungswinkel, plastische Fliessensätze, wirksames Verformungsmodul, leistungsfähiges Poissons Verhältnis, die Griffith Ortskurve und die Bestimmung eines Aufgehensfaktor BF1 der von Kaiser et al. (1996) eingefürt wurde. Das Modell wurde so kalibriert, dass es die Aufgehenfaktoren erzielte, die mit den Vesuchsangaben und den Fallstudien von Aufgehensmessungen in unterirdischen Abgrabungen übereinstimmen.

Jan 1, 2003

By Jack G. Gill, Richard A. Dick

Blasting safety is a subject that cannot be overemphasized. Two years ago, a study was published describing g a series of fatal blasting accidents which took the lives of ten metal and nonmetal miners during the period of May 1973 to August 1974.1 Each accident was described, and the direct causes were delineated. In each instance, specific MESA safety regulations were violated. Four of the victims were killed by drilling into explosives; two were killed by lingering too long in the vicinity of fuse rounds; two fatalities resulted from improper guarding of shots; one blaster did not retreat far enough to avoid the blast concussion; and another used an improper tester for checking an electric blasting cap. All of these fatalities could have been avoided by adhering to the MESA blasting regulations contained in 30 CFR Part 55 (Health and Safety Standards-Metal and Nonmetallic Open-Pit Mines), Part 56 (Health and Safety Standards-Sand, Gravel and Crushed Stone Operations), and Part 57 (Health and Safety Standards-Metal and Nonmetallic Underground Mines).

Jan 11, 1977

By Daniel N. Adams

The University Link project extends Seattle?s light rail from downtown to University of Washington (UW). It includes 5.0 kilometers (3.15 miles) of twin-bored, 6.4 meters (21 feet) excavated diameter tunnels, and two cut-and-cover stations. The Capitol Hill Station (CHS) requires an excavation 170.7 meters (560 feet) long, 22.6 meters (74 feet) wide, and 22.9 meters (75 feet) deep. The University of Washington Station (UWS) requires an excavation of about 238.4 meters (782 feet) long, 21.3 meters (70 feet) wide, and 33.5 meters (110 feet) deep. The project is within the glacially diverse soils of the Puget Sound region, below groundwater. This paper highlights major station and tunnel design elements, including the approach to support of excavation at both station boxes, and the site staging requirements.

Jan 1, 2008

By B. Samoski

In late 1994, EPA and OSM acknowledged that efforts by any one agency or by the many different agencies to remedy the water quality impacts of decades of contamination from abandoned coal mine lands in Appalachia would not be successful if their disjointed efforts were not unified and if the local watershed organizations were not included. The result of the collaboration between EPA and OSM was the creation of a statement of mutual intent which was a pledge by government agencies, watershed organizations, and the industry to restore watersheds degraded by acid mine drainage from abandoned coal. The presenter will describe the evolution of this pledge from a paper promise to on-the-ground remediation projects.

Jan 1, 2002

By William Hustrulid

Pre-split blasting is a primary technique for creating slopes with a minimum amount of unwanted damage to the remaining rock mass. Rock slopes created in such a way have both safety-related and economic advantages. The applications extend from road cuts to rock quarries to large open pit mines. For example, as deep open pit mines approach the end of their operating lives, slope steepening is one option to be considered. To be able to safely achieve and maintain steepened final slopes, good blast design techniques must be available and applied together with close operational control. Pre-split blasting is an important element in this slope creation process.

Jan 1, 2007

By C. D. Ashley, X. P. Garzon-Villalba, R. M. Lopez, T. E. Bernard

Federal standards for refuge alternatives (RAs) mandate that they not exceed a Steadman apparent temperature (AT) of 95 °F (35 °C) at an assumedmetabolic rate of 325W, a limit that appears to be arbitrary. Occupants in an RA spend most of their time at rest (a metabolic rate less than 325 W), and thermal equilibrium can likely be maintained at an AT > 35 °C. The purpose of this study was to examine the upper limit of sustainable heat stress during 4- and 8-h exposures at rest. Five men underwent five 4-h trials (phase 1: AT range 39 to 49 °C, 90% rh) and five 8-h trials (phase 2: AT range 46 to 56 °C, 90% rh) in a semi-recumbent position. Descriptive statistics for gastrointestinal temperature (Tgi), heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), sweat rate, fluid intake, urine color, urine specific gravity (USG), and changes in body mass are reported. Mean Tgi for all trials ranged from 36.9 to 37.3 °C, and mean HR for all trials ranged from 61 to 75 bpm. To determine the effects of increased heat exposure, differences in heat strain between 4- and 8-h trials were examined via repeated measures analysis of variance (ANOVA). As AT increased, there were no significant changes in ?Tgi and ?HR from 1 to 4 h in the 4-h and 8-h trials. During the 8-h trials, as AT increased, there was a difference in ?Tgi between 4 and 8 h. In conclusion, there was support for sustainable exposures resulting in no significant increase in physiological strain at an AT greater than 35 °C AT, with a sustainable limit (no increases in Tgi due to increases in AT) below 46 °C AT. Although the participants were not representative of coal miners, the results provide support for sustainable exposures greater than 35 °C AT at an average metabolic rate of 155 W.

Nov 8, 2019

By Bryan A. Bartley

"Jim Macdonald was promoted from Waterworks Engineer to Streetworks Engineer for the Wellington City Council. He thus took over the City quarry and responsibility for its performance. The crushing plant needed upgrading and he thought it would not be difficult to make a crusher to overcome a problem. If he had a longer association with the quarry industry he would have used conventional methods and equipment, so his invention arose from a fresh view of crushing.He invented the Barmac Rotopactor after observing a wear resistant chute with a lining of dead stone trapped above a piece of angle. This idea led to a rotor lined with trapped stone, rotating on a vertical spindle. In trying - a model rotor he observed the impact against a circular rill of stone in half an oil drum and thus was started a very fertile new area of developement in comminution. The writer helped in the developement and shares in the patents. Jim died in January 1982, just as the machine was becoming known and some 200 were in use in various countries. Most were working in hard rock quarries et that time but recent uses have carried the machine into the mining and mineral processing field. This paper is directed at that industry."

Jan 1, 1985

By J. R. Goode

"The Las Cristinas deposit contains about 10.2 million ounces of gold at a grade of 1.3 g/t. The deposit comprises a layer of fully oxidized saprolite (SAPO), a layer of sulphide-enriched saprolite (SAPS), carbonate leached bedrock (CLB) and carbonate stable or un-leached bedrock (CSB). Gold occurs at about the same level in all lithological groups. The bedrock units contain minor amounts of copper (about 0.1%) as chalcopyrite, while SAPO contains virtually no copper it having been leached and deposited in the SAPS zone.A previous owner started investigation of the Las Cristinas deposit in Venezuela in 1991. Over the next seven years, 1174 holes with a total length of 159 km were drilled, extensive metallurgical testwork, including pilot plant operations, were conducted and feasibility studies were completed. Construction was started in 1997 and again in 1999 but was suspended.Crystallex has been producing gold in Venezuela since the early 1990’s. In 1997, Crystallex acquired Inversora Mael which had held two of the claims to the Las Cristinas concessions since 1986. In September 2002, Crystallex entered into a definitive agreement with the Corporación Venezolana de Guayana, (CVG), to develop the Las Cristinas deposit.An extensive program of studies and testwork was started in early 2003 to determine an optimum development plan for Las Cristinas. Mine Development Associates, SNC–Lavalin Engineers and Constructors, SGS Lakefield Research Limited, J.R. Goode and Associates, and Professor A. Laplante at McGill University acted as the main contractors.Because of the potential value of by-product copper, earlier flowsheets used carbon-in-leach for SAPO, but processed all other ore types by flotation to produce a gold-copper concentrate with cyanide leaching of cleaner tailings to maximize gold recovery. Cyanide recovery was necessitated by the high copper content of the leach feed. Initial studies of available data by Crystallex revealed that direct leaching of all ore types would provide about 11% more gold recovery than the previously selected flotation route with reduced capital and operating costs.Bench and pilot scale studies have confirmed that a SAG-ball mill-gravity-CIL route is very effective for all ore types and will give about 89% gold recovery. This paper describes the recent testwork, discusses the proposed plant design, and presents economic data."

Jan 1, 2004

By J. C. Martin

Stmplified equations are developed for the flow of fluids in gas drive reservoirs in which the effects of gravity can be neglected. The results show that the pressure distribution is governed by a nonlinear heat flow type of equation, and the saturation distributions are related to the pressure by the same equations QS those developed by Muskat for the average pressure and saturations in gas drive reservoirs. Unrler certain conditions the equation for the pressure can be approximated by the linear form of the heat flow equatlon. This equation tk analogous to the equation for the pressure in single-phase compressible flow The analysis reveals that the equation for the pressure in n~ultiphase flows can be obtained directly from the equation for the pressure in slngle-phase flows by simply replacing the single-phase compressibility by the total compressibility and the single-phase mobility by the sum of the mobilities of all the fluids present. Perrine's method of pressure buildup analysis for multiphme flows is based on these same substitutions. Thus, the development presented in this paper constitutes a theoretical justification for Perrine's method of pressure buildup analysis. One of the most difficult problems associated with the production of oil is the determination of the flow of the fluids within the reservoirs. One purpose of this paper is to present the development of simplified equations for the flow in gas drive reservoirs. The other purpose is to present some of the needed theoretical foundation for the methods currently being used in the analysis of multiphase pressure buildup data. The analysis presented in this paper makes use of a partial linearization of the equations governing multiphase flows. It is felt that the process of linearizing or partially linearizing the nonlinear equations of multiphase flows can lead to useful results since this process has proved extremely valuable in the study of other fields of science and engineering where nonlinear equations are encountered. Pressure buildup data of shut-in wells have been used for many years to estimate the static reservoir pressure. These data have also been used in studying the aver- age permeability both away from and close to the well-bores. The majority of the buildup data are obtained from wells producing two or three fluids. As yet the theoretical foundations for the methods of buildup analysis used in connection with rnultiphase buildup data have not been established. A number of methods of analysis of pressure buildup data have been developed." Most of these methods apply only to single-phase flows, and almost all of the theoretical analysis is confined to single-phase flows. Perrine' developed a method of analysis for rnultiphase flows from the method for single-phase flows of Miller, Dyes, and Hutchinson.' He did this by simply replacing the single-phase compressibility by the multiphase compressibility and replacing the single-phase mobility by the sum of the mobilities of the fluids in the rnultiphase flows. Obviously, such a procedure lacks a certain amount of theoretical justification, and such practices can lead to erroneous results. Fortunately, Perrine's results have a theoretical justification, and this justification is presented in the following discussion. It is assumed that gravitational effects and the cornpressibility of the rock can be neglected. Under these assumptions the equations governing the simultaneous flow of gas, oil and water in porous media areo* The preceding equations can be expanded into the following expressions.

By John E. Tilton

During the past several years — much to the delight of producing firms and countries — copper prices have surged from under $1 to more than $3/lb. Anyone familiar with the industry also knows that since the early 1970s the long-run trend in real copper prices has been significantly downward. This sharp contrast between short-run and long-run trends raises the issue of the forces behind these developments. What has been driving short-run prices up and long-run prices down? Simple economics suggests that it is all a matter of supply and demand. When demand is rising faster than supply, prices will rise and vice versa.

Jan 1, 2006

By R. J. Lytle

INTRODUCTION Prior to excavation in soil and rock, it is useful to know the subsurface structure. This is important information both for safety and for equipment scheduling reasons. It is useful to know whether parts of the subsurface might be potentially troublesome or of different character than is generally thought present. By using geophysical probing, it is possible to infer the location and size of these unusual regions. The ground structure is commonly estimated from core samples taken from boreholes. These cores give a detailed knowledge of the structure in the borehole. However, knowledge of the structure exterior to the borehole can only be extrapolated from core data. By using seismic and electromagnetic cross-borehole geophysical probing, remote probing can be used to sense the region exterior to boreholes. A recent advance has significantly improved the state-of-the-art for defining the ground structure between boreholes. This new procedure utilizes large amounts of data and provides a detailed picture of the subsurface. The data processing algorithms used are similar to those in medical imaging of the human body using x-rays, a science called x-ray tomography. This imaging of the ground is called geotomography, which is a shortened acronym for geophysical tomography. Several examples of geotomography applied to imaging ground structure are presented. Our approach has been to probe the ground with electromagnetic and seismic waves. We map the region of interest with signals transmitted between multiple source and receiver pairs lowered in boreholes on opposite sides of the region (Figure 1). The received signals vary according to the transmission properties of the media

Jan 1, 1979

By A. F. Banks

"The last time I spoke to you the potash industry was at a low point. Markets were bad and the industry depressed. Many people had left and there was very little being done in terms of development. The current situation is very much changed. The oversupply conditions have given way to a very tight supply capability. All of the firms in the business are expanding in one way or another. These expansions will run from simple debottlenecking through to complete new projects.In New Brunswick, the Potash Corporation of America is proceeding with a new project and the Dennison - Potacan Project is in progress. In Saskatchewan, the Potash Corporation of Saskatchewan has an ambitious 2.5 billion dollar expansion program underway while those in the private sector are taking a somewhat less ambitious but equally significant approach to obtain further tonnage out of existing facilities.The significance of these expansions to mineral processors is that we can expect to see expanded employment opportunities and through necessity a surge in innovation and development in an industry that has been traditionally very conservative. This presentation will review potash processing with a view towards highlighting some of the more recent developments."

Jan 1, 1982