Search Documents

By D Craw

Sulphur-rich minerals such as authigenic pyrite (FeS2) are commonly associated with coal mine workings. Metallic elements such as arsenic (As), copper (Cu) and zinc (Zn) are enriched in the pyrite relative to their concentrations in the surrounding environment. Exposure of pyrite and coal to air and water results in a series of oxidation and hydrolysis reactions that are commonly catalysed by species of Thiobacillus bacteria. These reactions lead to a lowering of the pH in the drainage waters (acid mine drainage, AMD) and subsequent mobilisation of trace metals in environmentally significant concentrations. This study assesses the spatial distribution of As, Zn and Cu concentration in water in relation to pH and Eh (redox potential) downstream from the tailings at the Wangaloa opencast lignite mine in southeast Otago. This mine was abandoned in the late 1980s due to a decrease in the economic viability of mining the lignite. The area is showing the characteristic symptoms of AMD, which is detrimental to the health of several Pinus radiate growing on some of the tailings. The pH of the drainage waters can get as low as 2, and in some instances, lower, but it returns to near neutral (pH 6.5) up to 200 metres down stream from the base of mine waste piles. It is well documented that the atmospheric oxidation of pyrite is catalysed microbially, causing a substantial decrease in the pH of the drainage waters. Acidification is then counteracted predominantly by natural abiotic remediation processes occurring downstream.

Jan 1, 1999

By E. D. Wilson

A study of factors related to subsidence was specified in a project proposal entitled "Structural Analysis of Block-Caving Operation, San Manuel Copper Mine, Pinal County, Ariz.," approved by the Bureau of Mines early in 1953. This proposal was designed by Charles H. Johnson, then chief of the Base Metals Branch of the Minerals Division, Washington, D. C., assisted by Dr. Leonard Obert, chief of the Applied Physics Branch, Region VIII (now Region V), College Park, Md., and E. D. Gardner, chief mining engineer, Bureau of Mines, Washington, D. C. It read as follows: This project is a study of the mechanics of undercut block caving in a deep ore deposit. The San Manuel is a low-grade disseminated copper deposit containing nearly a half billion tons of ore lying at depths of 500 to 2,000 feet. Development is just starting. Production is to begin in 3 to 4 years (in 1956) at a rate of 30,000 tons of ore a day, or 60,000 tons of copper a year. A Government loan of $90,000,000 /subsequently increased to $94,000,000/ and a long-term Government purchase contract support the capital investment, which will total about $110,000,000.

Jan 1, 1957

By M. Gaula

"Gold bearing deposits of the Witwatersrand basin are generally less than 2m thick and require conventional narrow-reef mining methods for extraction and employ explosives as a means of rock breaking. Optimal utilization of explosives is dependent on the overall design of the blast. The under-utilization of explosives arises when shot-holes are drilled inconsistently, overcharged, and when tamping is absent. This can be rectified by emphasizing the importance of good drilling practices as part of induction programmes and refresher courses. The project was aimed at determining whether or not explosives are being optimally utilized at project site. This was investigated through a study of the properties of explosives, mine standards, and recommendations for usage. Underground observations were made to determine whether or not mine standards were being adhered to. Historic data was obtained to establish the historic relationship existing between the quantity of explosives used (kg) and the production output (m2). This was then compared to the quantity of explosives the mine expects to use per unit of production. The results obtained were analysed to determine the presence and extent of over- or under-utilization. It was found that explosives are being under-utilized at the mine. More explosives are ordered than expected per unit of production. The explosives’ properties are not thoroughly exploited during blasting, thereby requiring the use of more explosives than prescribed. Paper written on project work carried out in partial fulfilment of BSc. (Mining Engineering)"

Jan 1, 2015

By Robert Boyd

The Diamond Markets ? Supply has continuously increased over the past 25 years ? However, global supply is expected to drop by 1 to 2% by 2015 ? Demand Driven Market ?Demand is expected to grow 3% annually through to 2015 ? Supply Squeeze Anticipated (2010 to 2015) ? Consumption is exceeding rate of discovery, mine development and reserve replacement ? These fundamentals are driving increased capacity and production at existing mines in South Africa, Botswana and Russia and new areas such as Canada ? Canada is now the third largest diamond producing country in the world ? These fundamentals are also driving record levels of exploration expenditures throughout the world with particular focus on Africa and Canada

May 1, 2006

By P. Massacci, F. La Marca, G. Bonifazi

Certain deposits of incoherent materials which are near the surface and exploitable by open-pit mining may be characterized in real time before they are mined through an analysis of ground-surface imagery. If the slice to be stripped is not overly thick, in fact, surface texture and color properties may be extrapolated to its entire thickness. Image analysis techniques to process ground surface images acquired in situ(or in the laboratory shortly after their acquisition) which yield pattern vectors representative of RGB color component distributions and HSB texture parameters have been developed. The techniques were applied to a mineral sandy ore deposit containing three different lithotypes. Geostatistical analyses showed that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multi-barycenter classification algorithm. Such in situ image-analysis procedures open the way to the proper selection of the ore to be mined, or the proper way for run of mine (r.o.m).processing, or the appropriate blend to be processed before or at the same time as the mining process itself is enacted.

Jan 1, 1999

The Acid Leaching Process for the Synthesis of Zeolitic Material from Paper Sludge Ash

Sep 13, 2010

By H Arvidson, C Morley

Reconciliation has become very topical over the last ten years but how do we distinguish what is good practice, and even more importantly, show how it adds value? Reconciliation at Anglo American has received support from the very top of the company and this has enabled success in the design and implementation of a range of processes, reporting activities and actions. Focus has been on full Mine Value Chain Reconciliation (MVCR) from Resource to Product and on proactive cross-functional engagement. A standardised set of reconciliation definitions and relationships are used at all mines across the company to diagnose planning and performance issues. Results are formally presented in an efficient dashboard format, accompanied by a concise narrative to communicate what has been learned and what is being done to correct, improve or change practices. Importantly, effort has also been made to sustain MVCR by embedding good practice and quantifying the benefit of reconciliation explicitly via linking results to value.This paper sets out the lessons learned from the past two-years’ journey, highlighting areas where good practice has been defined and achieved. A ranking for quantifying reconciliation confidence over time is presented as a means of putting results into context and continuously improving the reconciliation process. Finally, a solution to define the value that can be derived from reconciliation is described, detailing how cross-functional personnel meet monthly to review results and implement actions that are tracked in terms of value creation.CITATION:Morley, C and Arvidson, H, 2017. Mine value chain reconciliation – demonstrating value through best practice, in Proceedings Tenth International Mining Geology Conference 2017, pp 103–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

A New Ingersoll-Rand Turbo Blower The Ingersoll-Rand Co. has added to its Turbo Compressors and Blowers a low-pressure machine t o handle volumes from 3,000 to 35,000 cu. ft. per minute at from 1-2 ½ lb. These are particularly adapted to such service as foundry cupola blowing, atomizing oil for oil burners, supplying blast to heating and annealing furnaces of various kinds, blowing air for water-gas generators, pneumatic conveying and ventilating. They are of the single stage, double flow type and are furnished either electric motor, steam turbine or water wheel driven.

Jan 6, 1916

By R. G. Burdick

The problems presented by old mine workings affect both present day mining and land development. An automated method of locating these old mines from the surface using electrical resistivity techniques was de-veloped earlier under a Bureau of Mines contract. Subsequent Bureau research has refined the techniques and expanded the area of study to a variety of geologic provinces. During this research, six mining areas in the United States were in-vestigated with the Bureau's automated resistivity method. This report describes the mining areas involved and the results of the resistivity investigations, which showed a high rate of success in detecting old mines. It also describes the field measurement techniques and data analysis procedures.

Jan 1, 1986

By Emilie S. Williams

The Doyon Mine?s Zone 1 (Altered Zone), found along the southern boundary of the mine, encompasses approximately 20% of the mining reserves. The mineralisation is found in a series of steeply dipping narrow veinlets, which are contained in an extremely weak host rock: a sericitic schist with RQD values ranging from 0 to 20. Longhole mining methods are used, with either longitudinal or transverse approaches, depending on the width of the ore zone. Dilution is of critical importance in the mining of this zone, particularly in longitudinal stopes, where dilution levels have averaged 55% since 2000. Major factors influencing dilution in this zone include the stope geometry and standup time. A two-phase approach has been developed to mine and backfill longitudinal stopes: the top of the stope is pastefilled after approximately half of the broken ore has been extracted; the remainder of the ore is extracted once the plug has cured; and the remaining void is filled. This method has been used in six stopes to date, resulting in an average dilution of 17%. This paper details the application of this technique and its effect on dilution.

Oct 1, 2004

By Danny Riley, Brian Curry, Sandya Govindaraju, James Bain

Acute vibration causes vasoconstriction in naïve human subjects1. Vibration-induced decrease in skin perfusion has also been reported in the rat-tail vibration model 2. After vibration exposure, rat-tail arteries demonstrate vacuoles in smooth muscle cells, similar to that caused by pharmacological vasoconstrictors3. This study addressed the effects of different frequencies, durations and patterns of vibration on lumen size and vacuole formation using the rat-tail vibration model in male Sprague-Dawley rats (~300 g). Methods The different groups were: 4-hr continuous vibration at 30, 60, 120 and 800 Hz; continuous exposure durations of 5 min, 1 hr and 4 hr at 60 Hz; and 4-hr cumulative exposure of 60 Hz delivered intermittently in cycles of 10 min on and 5 min off. Acceleration was set at 49 m/s2 r.m.s. for all frequencies. Unanesthetized rats were restrained in cages on a nonvibrating platform with their tails placed on a vibrating stage driven by a B&K motor (4809). The sham control animals were also placed in the vibration apparatus but not vibrated. Room temperature was controlled at 25 ± 1°C. Ventral arteries from proximal tail segments 7 were immersion fixed in aldehydes, embedded in epon-araldite and sectioned (0.5 µm) for morphological analysis. Vascular lumen sizes were measured as the percent ratio of the lumen perimeter to internal elastic membrane length using Image J software (NIH). The number of vacuoles in the smooth muscle layer of each artery section was counted. Results Fig 1: Semithin sections of arteries. A. Sham control. B. 4-hr vibration 60 Hz. In vibrated arteries, the lumen decreases in size, and smooth muscle cells (SMC) exhibit vacuoles (arrow). Bar equals 40 µm for each panel. [ ]

Jan 6, 2006

By F. C. Gennari, D. M. Pasquevich

With the gradual exhaustion of natural rutile, there has been extensive research into its synthesising from lower-grade titanium minerals. The removal of Fe from pseudobrookite (Fe2TiO5) by chlorination was studied, using both isothermal and non-isothermal thermogravimetric measurements. Correlation of the results obtained from element distribution maps, scanning electron microscopy, energy-dispersive X-ray analysis and phases detected by X-ray diffraction in the chlorinated samples showed clearly two associated processes. First, the pseudobrookite particles reacted with chlorine and iron was removed selectively as FeCl3(g), leaving a solid residue rich in the TiO2 phases anatile and rutile, separated from an inner layer of unreacted pseudobrookite by a distinct interphase boundary. Second, chlorine allowed TiCl4(g) to form in the reaction bed, where it removed iron from the Fe2O3 crystals as FeCl3(g) and substituted Ti through a pseudomorphic reaction

Jun 21, 1905

By Thomas O. Glover

Cameroon continued to enjoy sustained economic growth that began with its independence in 1960. Growth in the gross domestic product (GDP) averaged 2.8% per year during the 1960's and the first half of the 1970's. Starting in 1976 and for the succeeding 10 years, the GDP accelerated rapidly owing to the coming on-stream of Cameroon's small but domestically significant offshore oil industry. In 1985, the GDP grew by 7.8%, but in 1986, it was only up 5.5%. The country's sustained economic growth in dollar terms of gross national product (GNP) per capita reached $1,075 in 1986. The ranking in GNP per capita by the International Monetary Fund put Cameroon in the middle-income category for developing countries. The sustained economic growth rate up to 1986 was due to the injection of income from oil into the economy, but crude oil price reductions in 1986 brought a slowdown. In 1986, crude oil production grew to 200,000 barrels per day, an increase of 8.2% from that of 1985. Most of the oil came from the Société Nationale Elf Aquitaine (SNEA) wells in the multifield Rio del Rey complex. Additional output came from the Moudi Field operated by Compagnie Française des Pétroles S.A. Proven oil reserves in Cameroon were 540 million barrels. At 1986 production rates, and in the absence of further discoveries, Cameroon will have exhausted its recoverable oil reserves by the year 1995. Owing to worldwide crude price reductions, the country's oil income fell 60% between 1985 and 1986, from $1.82 billion2 to $0.72 billion. Cameroon's refinery operator commenced operating the Sonara refinery in 1981 at Point Limboh. Sonara's capacity of 43,000 barrels per day was small by most standards. In 1986, natural gas reserves, estimated at 100 billion cubic meters, were not produced commercially because there were no domestic users. Proposals for a multibillion-dollar liquefied natural gas plant at Kribi had been submitted; however, work on the plant had not commenced.

Jan 1, 1988

By Grafton Thrasher

For the proper discussion of this subject it is necessary to incorporate in this paper the substance of part of an article published by rite in Metallurgical and Chemical Engineering for January, 1915. CAST-IRON TEST PLUG, SHOWING LOW MOTTLED AND MOTTLED FRACTURES. Several years ago, while I was thief chemist for a malleable-iron company, it occurred to me that the mere regulation of silicon was not sufficient to produce the desired degree of chill. But only after repeatedly encountering this fact in befit open-hearth and air-furnace, as well as cupola metal, was I led to regard variation in the total carbon as the principal cause of disturbance; and I resolved to determine the total carbon as well as the sill on ill every heat, and by a carefully prepared test piece to gauge the approximate degree of chill. The test piece selected was a round plug, 2 in. in diameter and 12 in. long, cast on end

Jan 10, 1915

By J. Björkvall, S. Ångström, L. Kallin

In this paper results from industrial trials of CaC2 injection during stainless steel production in an electric arc furnace at Sandvik Steel is presented. The main purpose of the investigation was to analyse the effect of the injection on slag foaming and final chromium oxide concentration in slag. The results show that both an increase in slag foaming and a decrease of the final chromium oxide could be obtained during the charges with CaC2injection. On the basis of the results, the economical requirements are also discussed. Both the technical and economical requirements could be achieved for steels alloyed with Mo. In order to secure the economical requirements for all steel grades of interest, the injection technology must be further developed. It would also be important to utilize the positive effect of the slag foaming on the electric energy consumption. The work has been performed as a part of MEFOS frame research programme with participants from Sandvik Steel, AKZO Nobel and Avesta Polarit. Keywords: stainless steel, EAF, slag foaming, injection, CaC2

Jan 1, 2004

By Anil K. Ray

This paper discusses in situ studies conducted at an Illinois Basin room-and-pillar coal mine to evaluate the performances of three different types of bolts under similar geologic conditions. The bolt types considered were the fully grouted passive rebar (FGPR), the resin-assisted mechanical anchor (RMAB), and the fully grouted tension rebar (FGTR). During the evaluations, the three types of bolts were installed in a single entry covering a span of three contiguous pillars with almost identical geologic conditions. The performances of the three types of bolts were investigated by instrumentting the bolts prior to installation as primary supports on cycle. Additional data on roof behavior was collected with extensometers and shear meters placed near the instrumented bolts. Excluding some time lapse right after installation, the performance evaluation of the three bolt systems was based on the data collected for over a year. Based on this study, it was found that the axial loads measured in the different bolt types did not show any identifiable patterns under the prevailing geological conditions at the mine. Therefore, the assumption that active bolts must be superior to passive ones is not always valid. Even though the studied mine did not have any thinly laminated, weak rocks in the immediate roof, the passive bolts performed as well as the active systems.

Jan 1, 2012

Between February and August of 1986, Dr Alfred Petrick visited New Zealand sponsored under a Fulbright grant administered by the New Zealand-United States Educational Foundation. The grant supported a research project completed by Dr Petrick having as an objective, the preparation of a preliminary economic evaluation of the mining of six Otago lignite deposits as a source of energy for steam power generation or in liquid fuels. The research is limited to consideration of preliminary geological and engineering data on the six deposits and to the time constraints of the Fulbright visit. This paper is a summary of the final Fulbright report. The complete report including the listings of the computer programs is available from the Otago School of Mines.

Jan 1, 1986

By J. S. Phipps, D. R. Skuse

"Aqueous slurries of fine particle size calcium carbonate are used in a diverse range of end-use products. In many cases, the end use performance is governed by the fineness of the particle size distribution. In turn, the maximum fineness of the particle size distribution is primarily determined by the efficiency of the dispersants used during the production process. Here we report the sodium polyacrylate mediated dispersion of calcite and kaolin. Firstly, we report a colloid chemical description of the dispersant behaviour and attribute the stabilisation to both steric and electrostatic mechanisms. Secondly, we describe how the understanding developed in the first part of the study can be utilised to produce more effective dispersant systems which allow the preparation of, added value, higher solids and finer particle size calcium carbonate slurry products.INTRODUCTIONConcentrated aqueous dispersions of fine, particulate kaolin and calcium carbonate are used extensively in the coating of paper. Currently more than 10 million tonnes of such dispersions are used annually in North America and Europe alone, and worldwide consumption is growing at around 3% per year.Generally, paper is coated to enhance its visual appearance. Firstly, coatings improve the optical properties of the blank sheet, i.e. its brightness (or whiteness), opacity and gloss. Secondly, they improve the physical properties of the sheet that will influence the quality of the final printed image, such as surface smoothness, porosity, and ink absorption. In order to achieve these aims economically, paper coatings must be applied at high speeds and with minimal drying costs.Kaolin and calcium carbonate pigments are the major components of most paper coating formulations. Particle size distributions are chosen to maximise the optical benefits that they confer, and to allow the production of formulations that can be easily pumped, handled and coated. Coating pigments are generally produced and transported as slurries, and so it is important to obtain dispersions with the highest possible solids content, both to minimise drying costs and the quantity of water transported. This paper examines the dispersant technology that is currently used in the industry and the mechanisms by which it functions, and illustrates ways in which this technology has developed and could be further improved in the future."

Jan 1, 2003

By Don A. Toth

Until recently, the fire protection systems used to protect mining equipment were based on generically designed, off the- shelf concepts. These systems were reliant on single agent approaches and were generally comprised of a series of small twenty or thirty pound chemical canisters that would discharge their contents when triggered by thermal detection means. As the equipment grew in capacity, the logic used to increase the protection was to add more chemical canisters to the system. Hydraulic excavators and large-scale mining trucks grew dramatically in size into the 1990?s and beyond; with this growth came the increase in major losses due to fire. This was evidenced throughout this period, and continues to be of great concern today. During this presentation you will learn of the significant changes that have come about as a result of this history. Today, dual-agent products, infrared detection and unit-specific, engineered systems are the primary phrases used when discussing how to best protect this equipment from fire loss. This session is a must for anybody looking to optimally protect their equipment assets and for those looking to renew and/or secure new insurance for high value equipment in the future.

Apr 1, 2005

By S. H. Brown

In our work as health physicists*, we do a lot of public speaking and interaction with the public on issues related to development of uranium mining and milling (?uranium recovery?) in the US. Understandingly, the public has important concerns about this. Accordingly, this paper is presented in a ?question and answer? format in which we have tried to capture what are some of the most common concerns we hear from citizens and address them. We have attempted to do so based on the best scientific information we have, representing information well documented in peer-reviewed scientific literature and consensus positions from both national and international scientific standard setting bodies and related committees. We have included some of the more important of these scientifically-based references to support the information provided. Practical space limitations prevent completeness in this regard in some cases. Visit the Health Physics Society?s web site or feel free to contact me directly for additional references, information or detail ? Steve Brown. The health physicist?s primary objective is to manage the beneficial uses of ionizing radiation while protecting workers and the public from potential hazards. For more information on what a health physicist is and on the Health Physics Society, visit the Society?s web site at www.hps.org.

Feb 23, 2014