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By James G. McKelvey

Owners have seen several major tunnel projects in recent years fall victim to a general reduction in the number of bidders as well as an erratic range of pricing. It should be noted though that this is not a universal trend and some projects have seen good competitive bids. Contractual terms and conditions are an important factor in attracting good competition. The Front End documents of tunnel projects have come under increasing scrutiny as tunneling contractors in the U.S. industry are looking much more closely at their risk exposure in the contract terms and conditions. Considering the amount of tunnel construction work upcoming in North America, it is important that General and Special Conditions are put together in a way that provides a reasonable basis to execute the Contract and also provide a fair, balanced and swift way to resolve disputes.

Jan 1, 2008

By Xun Hu, Jian Pan, Hongbin Yu, Deqing Zhu, Yanhong Luo

Lump ores are one kind of important burdens for blast furnace (BF), their metallurgical properties have significant influence on BF performance. In this paper, the relationships between the mineralogy of five natural lump ores and the metallurgical performance have been studied. The mineralogy study includes mineral compositions, microstructure and porosity, and the metallurgical performance covers reducibility index (RI), low-temperature reduction degradation index (RDI) and decrepitation index (DI). The results show that the complex lump containing hematite, and goethite has better overall metallurgical performance. For single lump, the RI of goetihte ores is higher, the RDI and the DI is strongly influenced by porosity. The hematite and magnetite ores have good anti-decrepitation and anti-RDI, but generally the RI is lower due to lower porosity, and the RI is related to the grain size, the smaller grain size is, the better reduction will be.

Jan 1, 2015

By J. W. Kramers, R. A. S. Brown

"Samples from seven test wells distributed throughout the surface-mineable area of the Athabasca Oil Sands have been evaluated to determine the amounts of heavy minerals present and the titanium and zirconium contents. The samples were treated to yield the size distribution of the titanium and zirconium minerals as well as their spatial distribution. The study has shown that heavy minerals are found throughout the surface-mineable area; concentrations range from 0.24 to 2.29 per cent (by weight), with a mean of 1.02 per cent. Titanium and zirconium contents vary throughout the area, and are found preferentially in the finer size fractions. •on the basis of preliminary calculations, the tailings streams from an oil sands plant would provide sufficient feed for a large-scale titanium pigment plant, and the tailings from one plant would provide sufficient zircon feed to satisfy Canadian demand for. metallic zirconium. Variability of the heavy mineral content and composition is such that the heavy mineral potential must be evaluated in detail for each mine site."

Jan 1, 1976

By R. J. T. Charles

Introduction An apparatus that will measure the surface area of a few of the simple minerals with a high degree of accuracy has been described by J. W. Bell (1). His apparatus consisted essentially of a photometric device that would measure the turbidity of fine particle suspensions. Turbidity, in this case, was considered as a function of surface area. Bell's method of surface area determination seemed to offer possibilities of extension and improvement to the point where it might approach a general method of particle size measurement. Theoretical and Practical Considerations of the Photometric Method In order to illustrate how turbidity may be considered as a function of average particle size, and to indicate the type of results expected from a photometric method of particle size measurement involving turbidity, the following theory may be hypothecated. If a number of particles, considered as spheres of uniform diameter, are placed at random in the path of a beam of light, the following expression, which will give the change in light intensity as a function of the diameter of the particles, the specific gravity of the material, and the weight involved, can be formulated from the Beer-Lambert Law:

Jan 1, 1951

Datun Concentrator currently processes complex sulfide ores in Gejiu Municipality, Yunnan Province, China. The ore contains much higher arsenic than other ores. The run of mine ore is fed to the concentrator to recover copper and tin by bulk flotation and gravity concentration, and then the other sulphides, such as pyrite, arsenopyrite, etc. didn?t get utilized and are discarded as tailings due to the high arsenic content. In order to utilize the pyrites in the tailings, a series of tests have been conducted for finding the solution of arsenic removal from high arsenic-bearing pyrite concentrates through simple flotation process. By means of orthogonal experimental design, the optimized levels and main factors have been found out for the roughing stage. Through selection of the effective in-organic depressants for the arsenic-bearing minerals, the arsenic in the pyrite concentrate can be removed to meet the requirement of sulfuric acid plant (As%=0.5%) by the open flotation process, i.e., one-time roughing and two-time cleaning.

Jan 1, 2014

By D. K. Steele

The domestic primary copper industry generates in excess of 600 million t of mining and mineral-processing waste annually. Most of the waste poses negligible environmental threat, but a small fraction, because of toxic or corrosive characteristics, may be subject to regulation under Subtitle C of the Resource Conservation and Recovery Act (RCRA) or other pertinent regulations. Among the wastes generated by various copper producers are flue dusts, slags, refinery-bleed solutions, and. acid-plant wastes. The U.S. Bureau of Mines (USBM) has researched methods to mitigate the environmental threat posed by copper-processing wastes while recovering valuable metals from these materials. Acid-leach processing of flue dusts has been demonstrated feasible along with sulfide treatment of liquid refinery wastes and acid-plant-bleed and gas-cleaning solutions to precipitate dissolved metals. In, addition, the feasibility of removing copper and molybdenum from slag, as well as stabilization of precipitated sulfide wastes by vitrification, have been investigated.

Jan 1, 2010

By C. P. PERIN, DONALD BELCHER

T HE production of pure iron by electrolyzing solutions of its salts has been the object of scientific curiosity and research for about 80 years; and in the last two decades a realization of the unusual physical and chemical qualities of electrolytic iron has turned the attention of chemists and metallurgists toward a commercial application of this accumulated knowledge. Thus Burgess and Hambuechen in America, . Cowper-Coles in England, and Fischer in Germany- devised methods, more or less successful, for the electrolytic refining of iron, but none of these processes has yet attained large-scale operation. During the war some interesting ,work was done in France and England on building up worn or defective machine parts by electrodeposition of iron. It remained for the Société "Le Fern in France to carry on the process commercially. For six years Les Fonderies et Forges. de Sainte-Maire et Gravigny and the works of Bouchayer & Viallet at Grenoble have manufactured pure-iron boiler tubes in competition with established practice. The French process originated in the researches of Anthelme Boucher in 1910, and was, not put into operation until several years of experimentation had passed.

Jan 1, 1921

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By J. S. Stewart

THE Mackenzie River Valley proper extends from Great Slave lake to the Arctic ocean (see map, Figure 1). From Fort Providence, near Great Slave lake, to Aklavik, near the Arctic coast, the distance by river is 1,000 miles. This will give some idea of the extent of the region. Throughout the length of the river valley, the Precambrian complex rocks are overlain by unaltered sedimentary rocks several thousand feet in thickness. These sediments are dominantly marine and Palaeozoic in age. In places, the Palaeozoic strata are overlain unconformable by Cretaceous an Tertiary sediments. The strata have been folded and, in general, the inclination of the beds to the horizontal is comparatively gentle. Here, then, we have the essentials for potential oil fields covering an area over 1,000 miles in length. This is probably the largest comparatively unexplored potential petroleum region in North America, and surface evidences of oil in the form of seepages occur in several places. Many of these seeps were known to the early explorers, and the first Geological Survey report on the Mackenzie River region, containing the results of field work carried out by R. G. McConnell in 1887-88, noted the petroliferous character of the Devonian strata and the indications of petroleum(l). This region is, however, handicapped by distance from markets and sources of supply of materials; by lack of modern transport facilities; by short season for river transport, and mountainous country separating the valley from the Pacific seaboard; and by the long winter season with weather that makes outdoor work difficult. These factors have tended to discourage the enthusiasm of would-be promoters, and so development in this region has been slow In 1920, a test well drilled about fifty miles northwest of Fort Norman discovered oil in commercial quantity, and three additional wells proved a small area to be productive.

Jan 1, 1944

By Lori Bassman, Cassandra George, Cullen McMahon, Md. Zakaria Quadir, Michael Ferry

"Complete and accurate analysis of subgrain microstructural features must include three-dimensional information. Three-dimensional electron backscatter diffraction (EBSD) data can be used to characterize these features; however their boundaries first must be determined. This cannot be accomplished simply with pixel-to-pixel misorientation thresholding because many of the boundaries are gradual transitions in crystallographic orientation. Fast Multiscale Clustering (FMC) is an established image processing technique that we have combined with quaternion representation of orientation to segment this kind of data. Segmentation algorithms often have issues handling images with both distinct and subtle boundaries. Our implementation of FMC addresses this by using a novel distance function and statistical analysis to take into account the variance in orientation of each feature. Although FMC was originally a twodimensional image processing algorithm it can be generalized to analyze threedimensional data sets. As an example, a segmentation of microbands in cold-rolled aluminum is presented.IntroductionThree-dimensional electron backscatter diffraction (3D-EBSD) is a method for mapping the local crystallographic orientations of points in a volume. The technique uses a dual beam platform consisting of a focused ion beam (FIB) and SEM with EBSD, where FIB is used for serial sectioning and EBSD for orientation mapping of 2D slices. These 2D slices may then be stacked to create a 3D volumetric data set.Typical uses of such a data set include characterizing the geometries and crystallographic orientations of surfaces between structures in 3D [1-5]. This involves identifying boundaries accurately, either in 2D slices with subsequent 3D reconstruction (as illustrated in Figure 1) or in the 3D data set. All such data sets present the challenges of i) aligning data slices to correct for instrument drift, ii) identifying relevant boundaries, and iii) implementing appropriate smoothing or interpolation algorithms. The focus of this paper is boundary identification."

Jan 1, 2011

By Howard K. Worner

"In a rewarding career spanning nearly two thirds of a century, the author has worked at the frontier of such diverse fields as the creep of metals, structure properties and production of novel dental and surgical materials, molten salt electrolysis for titanium production, greatly improving the productivity of large iron blast furnaces and of oxygen steelmaking. While each of these has given great satisfaction, special thrills have derived from the development of new methods for the continuous production or refining of both ferrous and non ferrous metals. A rewarding segment was the evolution of various aspects of WORCRA technology. Unfortunately, several of these inventions have been ""ahead of their time"". Introduction""I am greatly honoured by the convening of this meeting to recognise my contributions to pyrometallurgy. My appreciation is the greater because this is the third Howard Worner Symposium; the first took place in the University of Newcastle in 1988, close to my 75th birthday. It was arranged by the local branch of The Australasian Institute of Mining and Metallurgy with the theme, ""Frontiers in Pyrometallurgy"". The second was organised by the University of Wollongong in conjunction with the Australian Academy of Science and the Australian Academy of Technological Sciences and Engineering; it celebrated my 80th birthday and, at my request, covered a broad range of topics under the heading of ""Recent Advances in Science and Technology"". Now, this very international meeting on ""Injection in Pyrometallurgy"" has been convened by the G K Williams Co-operative Research Centre for Extractive Metallurgy in my alma mater. I am both delighted and honoured that the cosponsors are the TMS (USA) and ISIJ (Japan).Dr Madhu Nilmani consulted me about the field to be covered and I readily concurred because ""injection"" has been of keen interest to me since the beginning of the 1960s when I began my pioneering work on sequential oxygen (or air) injection into flowing streams for both refining of blast furnace hot metal to steel and for the continuous smelting-converting of copper and nickel."

Jan 1, 1996

By Missy Isaman

"Mixed ground tunnels come in all kinds. In rock tunnels with possible faults and high pressure water, the challenges are many. With the advent of Crossover TBMs, contractors can minimize machine wear in such conditions while maximizing efficiency. The newest generation of Crossover is exemplified by two projects in Albania and Turkey. A 5.56 m Crossover TBM destined for Turkey’s Gerede Water Transmission will be assembled using Onsite First Time Assembly (OFTA) from within an existing tunnel. The unique machine will bore through 30 fault zones requiring the TBM to be sealable to up to 20 bar so pre-consolidation grouting can be done. If boring under pressure is required, the TBM will bore sequentially using the screw conveyor fore and aft gates. Skewing further towards hard rock, a unique 6.2 m diameter Double Shield TBM with Crossover features was designed for Albania’s Moglicë Headrace Tunnel. The machine features closure doors and a sealing system to contain inrushes of water until they can be grouted off. This paper will discuss the unique aspects of the Crossover designs, including their inception as based on past projects in difficult ground, and their utilization at the two current projects. INTRODUCTION Specialized tunnel boring machines have been made for years to tackle specific types of ground conditions. Traditional types of TBMs bore within a specific set of ground conditions. If a project is located in a competent granite face, then a Main Beam machine is a good solution. In soft ground, Earth Pressure Balance (EPB) machines are the method of choice. Years of experience and engineering advancements have made both types of machines fast and economical solutions for tunneling. Unfortunately not all ground conditions are a perfect swath of one material, and the need for a more diverse machine is apparent."

Jan 1, 2016

By Fernando Cillóniz

Benchmarking es un proceso de comparación y medición de los procesos de negocio de una organización, con aquellos que lideran el mercado. De forma que se obtiene información para mejorar el desempeño de las empresas. En ese sentido, el presente texto señala la utlidad del Benchmarking en las empresas donde el uso de la Internet y las tecnologías de la información permiten hacer más eficiente las comparaciones e intercambio de experiencias y conocimientos, así como internacionalizar el proceso.

Aug 25, 2002

By Shibayama A.

In this research, an investigation of a process to selectively remove arsenic (As) and antimony (Sb) contained in enargite (Cu3AsS4) and tennantite/tetrahedrite ((Cu1,Fe)12(As,Sb)4S13) copper resources by leaching and precipitation were performed. First in the leaching process, the target was to selectively leach As/Sb and reduce their contents in the ores to <0.5 wt% followed by a second process to remove As/Sb dissolved in solution for environmental control. Enargite ore contained 3.65 wt% As while tennantite/tetrahedrite ore contained 5.40 wt% As and 4.85 wt% Sb. Alkaline leaching using NaHS?NaOH media at varying experimental conditions (temperature, pulp density, time, reagent concentrations) were performed to investigate the process. As/Sb precipitation studies were also performed to control high As/Sb concentrations in leach solutions by using elemental sulphur (So). Results from leaching studies showed that over 99% of As/Sb in the impure copper ores can be removed and their contents in the final solids reduced to <0.5 wt%. It was also established that such very high leaching could be achieved at 80°C within 1?6 h and pulp densities as high as 1000 g/L. The study also revealed that leach solution containing very high As/Sb concentration ranging from 5 to 20 g/L can be used as fresh solution for leaching of fresh ores until concentrations exceeding 35 g/L when it was sent to precipitation circuit for As/Sb removal. Addition of elemental sulphur at 90°C and fast cooling to 30°C allowed over 60% As/Sb precipitation and removed as Na3AsS4 and solution with reduced As/Sb concentration to leaching circuit for continuous use. Keywords: Enargite; Tennantite/Tetrahedrite; Selective Leaching; Precipitation; Sodium hydrosulfide;

Sep 1, 2012

By M. A. Bergougnou, I. Inculet, K. I. Burgess

This paper describes the electrostatic methods of separating various minerals, reviews the principles of fluidization and outlines the technique of electrostatic sorting in fluidized beds. The application of the method to the benefication of coal is emphasized.

Jan 1, 1970

By J. Kendall Hales

Jan 1, 2005

By A. Yazadni-Chamzini

Maintenance strategy selection plays a significant role in mining design. The nature of maintenance strategy selection is a complex multi-criteria decision making (MCDM) problem including both tangible and intangible parameters which are often in conflicting with each other. Moreover, when decision makers are uncertain in determining and defining the ratings and the weights of alternatives and criteria respectively, fuzzy theory provides an appropriate tool to handle the existing uncertainties. In this paper, a new fuzzy MCDM method based on the concepts of TOPSIS and AHP was proposed to evaluate the feasible maintenance strategy. The linguistic terms are employed to assess the ratings and weights. Fuzzy AHP is utilized to calculate the weights of the evaluation criteria; then, the rankings of alternatives are computed based on fuzzy sets theory and TOPSIS. A real world case study is presented to illustrate a potential application of the proposed model.

Jan 1, 2012

By Rob Barber

This paper shares the experience of the Alberta Energy and Utilities Board (EUB) Field Surveillance Branch over the past few years in building relationships with Aboriginal communities. Our goal is to provide and encourage best practices that may benefit you and your organization and result in strong, mutually beneficial relationships with a focus on Aboriginal communities. Historical information provides insight that aids in establishing effective working relationships with Aboriginal communities. An important component is appreciation of the perspective of these communities, which is achieved through awareness training. The use of local Aboriginal resource people as part of the training is recommended. A plan that is supported by management and staff is essential and lays the foundation for successful relationships. However, the plan must be flexible enough to change as circumstances warrant. The concept of having local people in communities address local issues is essential. This ?grass roots? approach, combined with the goal of exceeding a community?s expectations with respect to addressing issues, will go a long way to establish trust and credibility. Measuring the effectiveness of this work is the final building block to complete the picture.

May 1, 2004

By B Beale

Bow-tie analysis is a commonly used tool to identify and display risks that have the potential for an undesired hazardous event. The output of the analysis are bow-tie diagrams, which are an effective and versatile communication format that can be applied to any type of risk. Contrary to their simplicity, a proper bow-tie diagram that maintains its usefulness and clear communication is difficult to build. Over two decades assisting Major Hazard Facilities with bow-tie analysis for Safety Cases, several common mistakes have been identified. This paper aims to highlight those issues with examples and provide improvement strategies. A sample of the most common mistakes are: - overly complicated risk analysis - poorly scoped and defined terms - poor descriptions and justifications - identifying too many dependent controls. Overly complicated risk analysis leads to wasted time in obtaining data for little gain. The bow-tie diagram is only a model. Effort should be redirected into identifying and managing controls that will make a tangible difference to site risk. Broad scopes lead to enormous and confusing bow-tie diagrams for both the user and the workshop team. Defining the scope of the study, the consequence severity of interest and critical control characteristics creates focused workshops and targeted analysis. With more definitive scope, there may be more bow-tie diagrams, however, they are succinct and specific. Well described causes are imperative for clear communication to users, regulators and future bowtie review workshop groups. It is best to use common wording structures and explain the event stepby- step. Also, clearly document any likelihood calculations and use data references where applicable. Identifying all possible controls creates a false sense of security that there are many layers of protection. In reality, most controls are dependent on a single system or person and could all be compromised from a single failure. A definition of a ‘bow-tie’ control is required whereby it must be independent from other controls. Improving the bow-tie analysis process will assist operators in developing meaningful and ‘operational’ bow-tie diagrams to support risk management systems and practices.

Apr 16, 2024

The income of the Institute is derived from dues, subscriptions to MINING AND METALLURGY and sale of publications. These sources are fortunately supplemented by the interest from invested funds now amounting to over $500,000, a considerable portion constituting endowments for especial purposes. Aside from the medal funds the principal endowments are the James Douglas Fund for support of the Library, the Rocky Mountain Fund and the Seeley W. Mudd Memorial Fund. The income from the two last named is available for the support of research and a variety of other purposes. It is allocated by the Board of Directors upon recommendation of standing committees in each case. An active effort is being made to increase the endowments of the Institute, it being felt that unusual opportunities exist for research and public and professional service through the organization.

Jan 1, 1936