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By Judy K. Todd

Double benching has been utilized as an excavation technique in open pit mines for many years. This process involves drilling, blasting, and excavating the material for the design bench height. A second bench is then excavated without the creation of a catch bench, i.e. only minimal offset from the first bench face is allowed when drilling off the second bench. The result is a double high bench face or double bench. When drilling off the second bench, the offset of the drill from the bench face projects the lower bench face into the pit up to an extra five meters. This reduces the maximum attainable bench angle, enhances the probability of rock escaping the catch bench and increases the overall strip ratio. The generally utilized process of trim blasting also can impact on the final bench profile by contributing to blast damage of the face. BHP Billiton Diamonds Inc., Ekati Mine Diamond MineTM, has pioneered the usage of a technique that eliminates this offset. Double benching is accomplished by drilling a single, 30m pre-shear (two 15m benches) to define and protect the final bench profile. This article provides a comparison of the attained face angles obtained in the field utilizing both of the above methods, as well as a comparison with the analytically predicted angles prior to excavation.

May 1, 2002

By Ronald S. Conti

A new U.S. Bureau of Mines 6.8-L ignitability furnace was used to study the thermal autoignitability of dust clouds. This furnace has a quartz window to allow observation of the early stages of the ignition process and to allow measurement of the dust explosion temperature. Thermal ignitability data were obtained for various carbonaceous and metal dust clouds, with particular emphasis on various ranks of coal dusts. One of the reasons for the construction of the new 6.8-L furnace was to evaluate the effect of chamber volume on the measured autoignition temperatures. Therefore, data from the 6.8-L furnace were compared with data measured earlier in a 1.2-L furnace. The conclusion is that the autoignition temperatures measured in the 6.8-L furnace were only slightly lower on average than those from the 1.2-L furnace. These data on the minimum autoignition temperatures of various materials will be useful in analyzing the thermal ignition hazards of dust clouds in the mining industry and other industries that manufacture, process, or use combustible dusts.

Jan 1, 2010

By Jacek Paraszczak

L?exploitation rentable des gisements de type filonien constitue un problème important dans le contexte actuel de l?industrie minière québécoise. Les études effectuées depuis 1994 ont indiqué, que la technologie d?abattage mécanique utilisant l?outil hydraulique appelé « éclateur radial-axial » constitue une alternative intéressante par rapport aux méthodes conventionnelles par le forage et sautage. Les essais du prototype de l?éclateur ont prouvé qu?il est en mesure d?abattre les roches dures dans un environnement minier, mais sa performance dans les termes de masse du roc abattu dans une unité de temps a soulevé certaines doutes. Pour cette raison, une étude de préfaisabilité de l?éclatage en tant qu?une technologie d?excavation souterraine a été réalisée. Cet article présente quelques résultats des travaux effectués dans le cadre du contrat octroyé à l?Université Laval par le Ministère des ressources naturelles du Québec. Leur objectif principal consistait à comparer, pour les conditions des gisements filoniens, la productivité et les coûts des méthodes d?exploitation souterraine utilisant l?éclatage par rapport à celles conventionnelles. Deux variantes proposées de cette méthode ont été comparées avec la méthode conventionnelle sur le plan du coût (par tonne de minerai) et de la teneur de coupure de minerai d'or. Les études ont démontré que l?application de l?éclatage représente un potentiel de réduire ce coût, surtout dans les situations où l?abattage sélectif pourrait avoir lieu. Pour le cas de base on a trouvé, qu?il serait possible de réduire la teneur de coupure par la marge d?environ 16 ? 26%. Toutefois, les études de sensibilité ont démontré, que le coût dépend de façon important de la productivité d?éclatage, qui, pour sa part, varie beaucoup en fonction de paramètres du massif rocheux devant être abattu.

Oct 1, 2001

By H. O. Hofman

WHEN dry chlorine gas is made to act in the cold upon finely¬divided gold,' it converts the latter with evolution of heat into auro-auric chloride, Au2CI4, a hard, dark-red, hygroscopic salt. Moisture splits this salt into aurous and aerie chloride, Au2C14 = AuCI + AuCI3; treatment with water converts it into auric chloride and gold, 3 Au2CI4 = 4 AuC13 + Au,. Aurous chloride, when stirred with water, undergoes a similar decomposition, 3 AuCI = AuCI3 + Au,. These decompositions of auro-auric chloride and of aurous chloride furnish the explanation for the practice of moistening an ore before it is treated by the Plattner chlorination-process; practical experience having shown that gaseous chlorine gave an unsatisfactory extraction with dry ore. According to Rose,' fine gold is acted upon more slowly by chlorine than gold containing some base metal, e.g., copper. He also states that small quantities of silver increase the rate of solution, but adds that the coating of silver chloride formed checks, and finally stops, further action, if the percentage of silver be increased beyond a certain undetermined amount. Bromine' acts upon finely-divided gold in a manner similar to chlorine; the auro-auric bromide, Au2Br4, however, is not hygroscopic. Upon treatment with water it is decomposed as is the corresponding chlorine salt. It is generally believed that bromine does not act as energetically upon gold as does chlorine. This seems to be borne out by the results in the leach-

Mar 1, 1905

1. Domestic Production and Use: In 1979, 12 companies operated 32 primary aluminum reduction plants, with 3 firms accounting for 64% of production. Washington, Oregon and Montana accounted for 32% of the total production; Gulf Coast States 20%; other Northern States 32%; and other Southern States 16%. Based on published producer prices output of primary metal in 1979 was valued at over $6 billion. Aluminum consumption by 25,000 firms was centered in the East Central United States. Of aluminum consuming industries in 1979, building accounted for about 24%; packaging 23%; transportation 22%; electrical 11%; consumer durables 8%; and other uses, 12%.

Jan 1, 1980

By P Shen, K Hattori, H Pan, E Seitmuratova

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Ore-bearing intrusions in the Central Asian Orogenic Belt (CAOB) were examined from nine mines: Boshekul, Nurkazgan, Kounrad, Borly, Aktogai, Koksai, Baogutu, Tuwu and Erdenet. The intrusions are diorite, granodiorite and tonalite with SiO2 contents ranging from 58 to 75 wt per cent, and show mildly fractionated rare earth elements (REE) ([LREE]N/[HREE]N = 2.7–4.7) – light REE and heavy REE – and varying Eu anomalies ([Eu]/[Eu]* = 0.58–1.4). The ratios of Sr/Y vary from 7.9 to 115 and the contents of Y from 4.6 to 23.9 ppm. The parental magmas of the intrusions are intrinsically oxidised. Zircon grains in the ore-bearing rocks from large- and intermediate-sized porphyry Cu deposits show high Ce4+/Ce3+ ratios characterised by 65–422 at Boshekul (>4.1 Mt Cu), 76–480 at Kounrad (>4.8 Mt Cu), 90–280 at Aktogai (>12 Mt Cu), 80–250 at Erdenet (>11 Mt Cu) 74–370 at Nurkazgan (>3.9 Mt Cu), 100–210 at Koksai (>1.6 Mt Cu), and 71–340 at Tuwu (~2.0 Mt Cu). In two small deposits, the ore-bearing rocks display low values of Ce4+/Ce3+; Borly (0.6 Mt Cu) ranging from 28 to 158, and Baogutu (0.6 Mt Cu) from 29 to 113. The Ce4+/Ce3+ ratio of 120 distinguishes large intermediate-size deposits from small-size deposits. This information is potentially useful in exploration for porphyry Cu deposits in the belt.CITATION:Shen, P, Hattori, K, Pan, H, Jackson, S and Seitmuratova, E, 2015. Granitoids associated with porphyry Cu deposits in the Central Asian Orogenic Belt – characteristics and oxygen fugacity, in Proceedings PACRIM 2015 Congress, pp 377–382 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Reginald S., Dean

The commercial availability of electrolytic manganese has greatly changed the position of manganese as a nonferrous alloying metal. Manganese metal commercially available up to about ten years ago was reduced with either silicon or aluminum and contained substantial amounts of the oxides of these metals and other impurities. Manganese was accordingly not available as an alloy base and its addition to copper-base and nickel-base alloys was generally limited to a manganese content of a few per cent. Several special alloys like manganin contained up to 12 pct of manganese.

Jan 1, 1953

By Jo Katembo, Patty Bwando, Patient K. Ilunga, Yves Kalubi, Emman Mulaj

"From 2010, the dolomite concentration in the ore fed to the Usoke Plant increased, resulting in a significant increase in the gangue acid consumption and Mg build-up in the circuit, and thus an increase in the Mg:Co ratio in the plant solutions. This affected the Co salt grade, reagent consumption, filtration and drying capacity. Efforts were put in place to minimise the acid consumption and consequently the Mg dissolution (such as use of pre-diluted acid), but the benefits were negligible. Various efforts were then initiated by CHEMAF to improve the cobalt plant productivity (quantity and quality) by process changes, dual precipitation and seed recycle. The positive results obtained in the laboratory were successfully implemented on plant scale. A change in the process from a single-stage precipitation with Na2CO3 to dual precipitation using a combination of Na2CO3 and NaOH improved the capacity of the Co salt filtration by 30%, the Co salt grade and drying capacity by 50%, and reduced the reagent consumption by 22%. Implementation of precipitate seed recycle increased Mg rejection by 40%, improving the Co salt grade from 20% to 25%, and yielding a further drop in reagent consumption. INTRODUCTION CHEMAF (Chemicals of Africa), a mining company located in Katanga province of Democratic Republic of Congo (DRC), has been operating since 2003. The Usoke hydrometallurgical plant treats the Cu-Co ore from the Etoile pit to produce Cu cathodes via a leach–solvent-extraction (SX)–electrowinning (EW) circuit and Co salt via a selective precipitation process. The plant was designed to treat run-of-mine (ROM) ore grading 6% Cu and 1.5% Co; but, in 2008, due to a decline in grades, a heavy-media separation (HMS) plant was commissioned to enrich the low-grade ROM (3.5% Cu and 0.5% Co) up to 8% Cu and 1% Co before feeding it to the hydrometallurgical plant. Co is recovered by precipitation of Fe and Al with limestone, followed by Co precipitation as Co carbonate using sodium carbonate (Na2CO3), also known as soda ash. 85% of the final effluent from cobalt precipitation is recycled back to the plant as process water; the balance, 15%, is bled out and compensated for by fresh water top up to control and retard the rate of sodium sulfate build up."

Jan 1, 2015

By K. G. Philo, R. C. W. Webber-Youngman

mining, where data-driven decision making optimizes resource extraction, enhances safety, and ensures sustainability. The adoption of digital technologies like artificial intelligence (AI) and the Internet of Things has amplified the importance of digital information. However, the integrity and security of this information are paramount, leading to the exploration of blockchain technology as a potential solution for secure digital value exchange in mining. This research examines blockchain's capabilities, drawing insights from its applications in sectors like banking, government, healthcare, and entertainment, and evaluates their relevance to mining's core value chain processes. The study identifies blockchain's distributed ledger technology, cryptographic security, and decentralization as unique advantages that can revolutionize mining by enhancing transaction speed, reducing costs, and improving supply chain transparency and compliance with sustainability standards. Blockchain's transparent and auditable records can enhance business transparency, fostering trust among stakeholders, including investors and regulatory bodies. The technology's consensus mechanisms and smart contracts further promote trust in collaborative ventures. This research provides a foundational understanding for decision-makers in the mining industry to evaluate blockchain's feasibility and potential return on investment, guiding strategic planning and resource allocation for blockchain applications. By leveraging blockchain, mining companies can optimize operations, improve sustainability practices, and establish a robust foundation for future growth, positioning blockchain as a transformative technology in the sector

Jul 10, 2024

By AIME AIME

HOWARD H. PRESTON, professor of economics and business at the University of Washington, presented a paper before the North Pacific Section, A.I.M.E., on Jan. 23, on the "Economic Aspects of Gold and Silver." He carefully reviewed recent governmental actions that have affected those metals and gave an interpretation of their effects. A brief excerpt from his address; follows: Including the proclamation of March 6, 1933, the principal steps of the present Administration which have carried the United States off the gold standard and led up to the present program have been: (1) The Presidential proclamation of March 6 controlling gold. (2) The monetary sections of the Emergency Banking Act of March 9. (3) Mobilization of gold under Executive orders issued March 10 and April 5. (4) The gold embargo by Executive order, April 20. (5) The controlled inflation bill, May 12. (6) The joint resolution abrogating the gold clauses, June 5. (7) The Executive orders on newly mined gold, Aug. 28. (8) The President's radio address of Oct. 22 and the R.F.C. gold-buying program. (9) New anti-hoarding order calling in small holdings of gold, Dec. 28, 1933 and Jan. 15, 1934. (10) Nationalization and revaluation of gold' (Message to Congress, Jan. 15).

Jan 1, 1934

Q: It is May 1961 at Bill Wrather's Washington house. Bill, think back to your first job after college. Wrather: Perhaps I ought to go back a little bit further than my first job. I entered the University of Chicago with the idea of studying law. My intention was to take a 4-yr liberal arts course and superimpose a law degree on that. But during my undergraduate work I fell under the influence of R. D. Salsbury. He decided I had some talent as a geologist and influenced me to take a geological course. Nevertheless, I did not give up the idea of law. While in school I took a spell of typhoid fever and almost died. The doctor recommended outdoor exercise, so a geological job seemed logical. W. H. Emmons was a graduate student in the University and he interceded with Dr. Hayes of the USGS. I went on the payroll as assistant packer at $60 a month. I had one of the most glorious summers I ever spent in my life. That fall and the following year I took law courses and became thoroughly convinced that I was cut out for a geologist rather than a lawyer. I finished up my law work in 1908 while waiting for a job with Bill Emmons, who was doing a careful study of Goldfield and Tonopah.

Jan 4, 1964

By C. Richard Tinsley

INTRODUCTION The economic analysis (Chapter 3), the engineering studies (Chapter 10), the credit structure (and the consequential funding sources) - Chapter 11, and the overall feasibility structure for any venture are all directed to determining one major decision element: How much and how certain is the reward for taking these risks? Risk assessment is a surprisingly weak area of analysis and is usually addressed in a checklist fashion. It is much preferable to deal within a risk system so that the inevitable tradeoffs among risks are correctly made. DEFINITION The first step toward risk definition must be to ascertain all of the risks to which a project or a company is exposed; otherwise one will remain ignorant of the possibility of a financially crippling loss until it occurs. (Carter and Crockford, 1974). However, simply stating what "risk" is can lead to debate. For example, risk could be (adapted from Vaughan, 1982): -the chance of a loss - uncertainty of loss -possibility of loss - uncertainty -dispersion of actual from expected results - probability of an outcome different from the one expected - possibility of an occurrence of an undesirable contingency -a condition in which a possibility of a loss exists. For the minerals industry financier, the last definition is probably the most appropriate. However, from a mineral company's point of view the definition might well include the possibility of not achieving the expected financial return. RISK CLASSIFICATION Risk identification will be readily agreed as the all-important first step. There are five major "branches" of risk classification. These are: -Statistical -Modellers -Checklist -Project Financing -Insurance The Statistical set discovered probability theory and any risk discussion soon deteriorates into a mathematical jungle (Megill, 1977; Hartman, 1976; Reutlinger, 1970; and Pouliquen, 1970).Their use of terminology tells its own story: coin toss (binomial distribution), gamblers' ruin, delphi (oracle) techniques, monte-carlo simulations, random walks, etcetera. These techniques inadequately represent the judgements necessary in an increasingly complicated and interrelated world. The risk Modellers have turned to the computer to handle these inter-relationships but soon find barriers because of "simultaneity". Certainly the computer has its uses to conduct various analyses (marketed as "sensitivity" analyses) but very often one finds that this involves changing one or two variables at a time, all other things being equal. Unfortunately, in a modern and complex world all other things do not remain equal. The statisticians will, no doubt, jump to their own defence by citing this

Jan 1, 1985

By Walter E. Vanderpool

Three drilled foundations for an elevated water-tank were instrumented, tested and monitored during construction and the first two years in service. One shaft was load tested by the Osterberg method. A void was detected in one shaft by cross-hole sonic logging, pulse-echo logging and concrete coring. The void was instrumented, hydrostatically tested and pressure grouted. The shaft was ?abandoned? and replaced by two smaller shafts with a straddle beam cap. One of the replacement shafts and the cap were instrumented. The strain that appeared in the abandoned shaft, the replacement shaft and the cap were monitored during the remainder of the construction, through the commissioning test and the first two years of service. The results demonstrate the precision and sensitivity of the vibrating wire strain gage.

Jan 1, 2004

By Rodger C. Fry

Underground coal mining has been active within the East Mountain property since the mid 1950's. As a result, coal from two seams has been extracted within large areas allowing surface subsidence to occur. Monitoring of subsidence annually, began in 1981 using on the ground conventional monumentation, surveying and photogrammetric monitoring. The data collected has shown the time benefits of photogrammetry and the relationship between observed subsidence and the geometry of the mined out area below.

Jan 1, 1986

By Robert McClure, Frederic Leclercq, Ricardo Chavez

With significant vibration control and fragmentation challenges facing them, the CBS quarry (department of the Nord) successfully integrated a technical partner and mine to mill optimisation to deal with a difficult environment. For the last three years, CBS has been conducting a global production monitoring program similar to the mine to mill concept used in the mining industry. This concept consists of optimising the drilling and blasting while monitoring the effects on the downstream chain (vibration control, loading, hauling, crushing, plant output). Blast optimization is ensured by systematic control of the blast geometry (volumes, patterns, bench and face anomalies, drill deviation) and by the use of constant specific energy blasting. Constant specific energy optimises the work of the explosive in a blasting operation and, when combined with a high accuracy programmable electronic blasting system, reduces the impact of blasting on the environment and enhances blast performance. These techniques ensure consistent blasting results and hence improved site productivity. The improvements achieved have been identified thanks to an effective system designed to monitor the key production parameters.

Jan 1, 2007

By D. K. Ingram

In situ horizontal stresses were measured to determine the influences of geologic anomalies on the regional horizontal stress field in two coal mines in southern Illinois. Stress measurements were obtained near a normal fault having a 121-ft displacement at the AMAX Wabash Mine and a large coalbed want at the Kerr-McGee Galatia No.5 Mine. Horizontal stress measurements were completed using a Bureau of Mines borehole deformation gauge. The average maximum and minimum horizontal compressional stresses at the Wabash Mine were 1,400 and 800 psi, with the direction of maximum stress ranging from N 78° W to N 83° E. At the Galatia No.5 Mine, the averages were 1,500 and 500 psi, with the direction of maximum stress ranging from N 85° E to N 75° E. Generally, the geologic anomalies appear to have no dramatic effect of the regional horizontal stresses. However, subtle differences between stress measurements suggest an influence by the fault zone at the Wabash Mine. The larger anisotropic stress conditions at the Galatia No.5 Mine could be responsible for the increase in kink zones and directional roof failures.

Jan 1, 1988

By W. Chi, R. Regan, R. A. Washington

"In uranium mines, the purification of underground mine air can be accomplished by the removal of dust particles and radon daughters using filters. Full-scale statistically designed experiments with flow rates up to 10,000 cfm have been conducted at Denison Mines Ltd. on mine air filtration with vermiculite as a filter material. Various filtration bed thicknesses were chosen, with different face velocities through each bed thickness. Results on total dust, respirable dust and radon daughter collection efficiencies were analysed statistically. It is shown that these collection efficiencies are directly related to the filter bed thickness. However, the different face velocities seem to affect only the collection of radon daughters. Optimum collection efficiencies for a clean bed of about 30% were found for respirable dust and radon daughters, and about 41>% for total dust, using an 8-in.-thick bed and a face velocity of 500 fpm. Dust build-up on the filter bed during operation led to an increase in collection efficiency, reaching 40 to 60% after two weeks."

Jan 1, 1973

By Alastair Torrance, Mitchell Nipperess, Andrew Olsson, Italo Onederra, Gary Cavanough

Components of bulk explosive products include ammonium nitrate, water, fuel, stabilizers, and calcium nitrate. The physical attributes include prill/emulsion ratio, density, and viscosity and in the case of prilled ammonium nitrate, hardness, size distribution and fuel oil absorption. These components and attributes in conjunction with ground conditions determine all aspects of explosive performance including the risk of fume. This paper presents a fume risk assessment matrix of explosives components and physical attributes as a function of a simple description of ground conditions. Instrumentation to provide a measure of the quality of the explosive product are also described and these include both “on bench” physical measurements and laboratory analysis. “On bench” methods include “in hole “density, velocity of detonation (VOD), detonation pressure and detonation temperature. Part of the quality control process involves a mobile laboratory unit which at this stage can provide measurements of water content, ammonium nitrate content, calcium nitrate content, fuel content, prill characteristics and prill/emulsion ratio. This unit can be taken to sites to enable the testing of bulk and sensitized products at site rather than after transportation.

Jan 1, 2015

By Vaughan R. Voller

"The wide range of length and time scales found in solidification processes are outlined and discussed. Methods for Direct Microstructure Simulation (DMS) are introduced. Key features in sharp interface and phase field models are presented. Concepts in micro-macro solidification modeling are covered. Basic details of microstructure and segregation models are provided. A description of a recent segregation micro-macro model is presented in detail.IntroductionA solidification process involves the containment of a liquid region, which, due to cooling, transforms over time to form a fully solid product. The development of the solid microstructure and the segregation of solute components during this transformation are controlled by phenomena that occur across a wide range of length and time scales. A ""successful"" model of a given solidification process needs to account for these phenomena. Standard models of solidification employ a discrete grid of node points and associated volume elements in the special domain, with a discrete time step to track the transient changes of nodal values, describing the composition and microstructure. Through the use of such models significant progress has been made towards a complete understanding of solidification process and phenomena (see the conference proceedings in Refs [1-9]). As solidification models become more sophisticated, however, they all run into the problem of resolving the full range of disparate space and time scales.Two approaches can deal with this problem1. Direct Microstructure Simulation (DMS) where the grid size and time step are chosen to scale with the smallest length and time scales of the given problem.2. Micro-macro modeling where the grid size and time step scale with the macroscopic process scale and phenomena at smaller scales are accounted for via sub-grid modeling and volume averaging.Currently full DMS of solidification is beyond the reach of available computer power and the application and development of micro-macro models is an important and critical research area."

Jan 1, 2001

By Gregg Davidson, Lonnie Jacobs, Brett Zernich, Alan Howard, Robert Pintabona

All Rights Reserved. Printed in the United States of America. Information contained in this work has been obtained by SME, Inc. from sources believed to be reliable. However, neither SME nor its authors guarantee the accuracy or completeness of any information published herein, and neither SME nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SME and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Any statement or views presented here are those of the authors and are not necessarily those of SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2014