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By Steve Kral

It seems that mining has been in the doldrums for awhile. Except for gold, metals prices remain depressed. And economic conditions in the United States and around the globe have put governments in a financial bind. This affects new building and infra-structure repairs, which, in turn, have a major impact the building materials industry. Add to that the severe environmental and regulatory restrictions placed on the mining industry in developing new mines and expanding existing ones. It’s enough to make a mining engineer/geologist/metallurgist go sell real estate. So why do those employed in the mining industry stay in the business and remain optimistic? Many of them will say that they have been through down cycles before and know that an upswing is in the offing. They also know that society will always need the commodities they produce. And they love the challenge. The challenge in mining’s case is producing commodities as cheaply as possible, in an environmentally sound manner and improving the quality of life in the communities where they work.

Jan 1, 2003

By K McLeod

{Figure 1} The Placer Dome-Western Areas Joint Venture?s South Deep Twin Shaft Complex, has been planned and dreamt of for nearly 20 years. [ ] The gold reserve at the bottom of these shafts is one of the largest single intact gold deposits remaining in the world today, containing an estimated 57 million ounces. This is about the size of the fictitious reserve created by inventive prospectors for the infamous BREEX scam in Kalimantan about ten years ago and about the size of the reserve Harmony claims as its own in it?s current hostile takeover bid for Gold Fields. So it is certainly of the magnitude that dreams are made of. [ ] {Figure 2} The unique orebody lies in a continuous, highly concentrated, thick deposit, an estimated twelve kilometres along dip and a two kilometre wide strike. Due to the thickness of some sections of the reef, up to 60 metres in places, bulk mining methods will be required for it?s extraction. [ ] {Figure 3} The twin shaft system comprises a main shaft which had an initial design depth of 2765m and a ventilation shaft of 2760m, making them the world?s deepest to be sunk in a single lift. The shafts were

Jan 1, 2005

By G. X. Wang, R. E. Siemens, M. C. Fuerstenau, D. Chandra

Soda roasting of concentrates from Mouat, Montana, was performed in a temperature range of 450 to 650 degrees C and chromium was solubilised by water leaching at room temperature. It was found that high extraction yields of chromium were primarily dependent on the conversion of Cr3+ to Cr6+ during the roasting step, and this was enhanced significantly by simple attrition of chromite particles during this step. Gangue impurities (mainly Si) were more detrimental to Cr extraction than lattice impurities such as Al or Mg. It appears that oxidation proceeds into grains along a preferred crystallographic plane in the cubic lattice of the chromite. The effects of roasting time, temperature, soda to chromite ratio and particle size on the extraction of chromium are presented

Jun 18, 1905

By T Rock

This paper looks at recent advances in the United Kingdom (UK) tunnelling industry with particular reference to the A3 Hindhead Project. A 1.8 km long twin bore tunnel is the centrepiece of the A3 Hindhead scheme, which commenced construction in 2007 and is being delivered under a UK Highways Agency early contractor involvement (ECI) contract. The proposed construction methodology is progressive mechanical excavation of a horseshoe-shaped tunnel with shotcrete installed close behind the face using robotic spraying equipment. The tunnelling medium is a æsoft rockÆ sandstone for which there was little previous tunnelling experience, requiring extensive geotechnical investigations and an innovative approach to lining design. A 240 m long section though sandy material utilising a steel pipe umbrella is also required. This paper describes the development of the tunnel planning and design including the most recent developments in UK road tunnels. The innovative approach to the design of the following is discussed:the æpermanentÆ primary lining,an observational technique allowing optimisation of the steel pipe umbrella design,a plain concrete secondary lining designed for resistance to a hydrocarbon fire, anda spray-applied membrane.

Jan 1, 2008

By Fábio Rogério do Carmo

O ar soprado é uma das principais utilidades responsáveis pelo processo de transformação do minério de ferro em gusa no Auto Forno. Para que ocorra o processo de redução o ar soprado é superaquecido nos regeneradores dos autos fornos a uma temperatura de 1.300°C. Este energético é fornecido na CSN-UPV pelos turbos sopradores da Central Termoelétrica nº 2 (CTE#2), área dos Motos Sopradores 1 e 2 e os turbos sopradores n°1 e 3 da CTE#1 que operam com a velocidade reduzida 24 horas soprando para atmosfera e consumindo vapor de 30Bar. Devido à obsolescência do sistema de ar soprado da CTE#1, alto custo de operação e risco para a segurança operacional, este trabalho apresenta o estudo do problema em questão, a metodologia utilizada para desativação do ar soprado da CTE-1 e a redução de custo.

Sep 25, 2017

By William F. Hahn

This report describes an illumination system suitable for use in a slope under construction, Simulator work was performed using actual lighting hardware to verify adequate light levels to meet MSHA proposed regulation (as published in the Federal Register, January 13, 1977). The sequence of operating activities for two different slope driving sites are discussed and lighting requirements are defined for each,

Jan 1, 1981

By D. Noort, M. Dawborn, D. O. del Castillo

This paper was originally presented at the North American/9th US Ventilation Symposium, June 2002, Kingston, Ontario, Canada. Reprinted with permission of the publishers, A.A. Balkema Publishers, Rotterdam, Netherlands. This paper is a study of the ventilation, cooling and refrigeration system design of the Mindola copper mine in Zambia. The challenges that were addressed varied from the restrictions imposed by an ageing infrastructure to the requirement for increasing the annual production rate, coupled to the introduction of a higher level of mechanization while maintaining acceptable conditions and limiting total ownership costs. A description of how the ventilation, refrigeration and cooling systems were modelled in order to obtain the projected heat loads associated with two different mining methods over the life of the project. The methodology included a number of iterations to optimise the design and include aspects such as the expected inrush of hot fissure water, the operation of diesel machinery at depths in excess of 1500m below surface, developing a cost-efficient cooling strategy and selection of the refrigeration machinery to meet the requirements imposed by the cooling strategy. This paper demonstrates the successful implementation of an integrated design approach.

Jan 1, 2005

By C. Ogasawara

This document describes the direction and progress of the Bureau of Mines Oil Shale Mining Environmental Research Program as of January 31, 1979. It is aimed at focusing the Bureau's role in environmental research supporting oil shale development with respect to the activities of other involved government agencies and private industry. Environmental considerations in oil shale extraction, such as ecological disturbances, health and safety hazards, waste management, and socioeconomic impacts, are discussed along with the type of research known to be planned by organizations to ameliorate these problems.

Jan 1, 1979

By Richard Mainiero, Donald A. Hurd, James H. Rowland

In previous conferences the authors have reported on toxic fumes generated by the detonation of ANFO. The research reported here extends the earlier work to include an emulsion blasting agent and ANFO/emulsion blends. Explosive mixtures were shot in 4-inch Schedule 80 steel pipe in a chamber in the experimental mine at the Pittsburgh Research Laboratory (PRL). Following each shot, the fumes in the chamber were analyzed using on-line instrumentation. A major goal of the research was to gain a better understanding of the factors that lead to the generation of toxic fumes in blasting operations. Earlier studies have suggested that the high nitrogen dioxide and nitric oxide concentrations in product clouds might be the result of the poor confinement provided by relatively weak ground strata or the exposure of the explosive to ground water prior to shooting the shot. Various mixtures of ANFO and emulsion were detonated in schedule 80 steel pipe and galvanized sheet metal pipe to evaluate the effect of confinement. Explosive mixtures were also allowed to soak in water for less than one day, one week, one month, and two months to determine which explosive mixtures would be degraded and observe what effect this degradation had on fume production. Results indicated that the production of nitrogen dioxide increased with low confinement of the detonating explosive and with exposure of the explosive to water.

By Dong-Hyeun Koh, Yun-Soo Lee, Min-Seok Kim, Hyoung-Wook Kim

High strength AA7068 (Al - 7.88 wt.% Zn - 2.68 wt.% Mg - 2.07 wt.% Cu) aluminum alloy strip was successfully fabricated by horizontal-type twin roll casting. A simulation technique was used to obtain the range of casting conditions for fabricating strip without defects. The cast strip with thickness of about 5 mm was hot rolled, intermediate annealed, cold rolled to final thickness and subsequently annealed at various temperatures. Tensile properties of annealed and the aged specimens were evaluated at ambient temperature. Tensile strength and elongation of the annealed sheet are about 365 MPa and 28%, respectively. Also, the tensile and yield strength after the aging at paint baking condition (180 °C x 0.5 h) are 586 MPa and 551 MPa, respectively. Therefore, it is expected to show good formability prior to press or stamping and also provide high dent resistance after paint baking treatment.

Jan 1, 2015

By N. O. Taylor

THE failure, by swelling, of several cast aluminum-zinc, spiral, pump rods, used to circulate water in a constant-temperature bath, brought up the question as to whether the presence of tin in varying quantities would have any appreciable influence in controlling this action. Previous workers had found the same difficulty with aluminum-zinc alloys, due to their swelling in water or solutions of electrolyte^.^ It was known that pure aluminum was practically insoluble in concentrated sulfuric and nitric acids, presumably due to the formation of an oxidized film on the surface. Concentrated sulfuric acid had little or no effect on pure zinc and tin and concentrated hydrochloric acid would attack all three metals. These facts aroused curiosity as to the probable reaction of the ternary alloys of these metals, and tests were made to determine their resistivity to the action of common laboratory reagents. Samples, covering the entire range of the ternary series of aluminum, zinc and tin alloys, were made up from good grades of the commercial metals.2 The materials were melted, at as low temperatures as possible, in graphite crucibles in a gas-fired crucible furnace. Graphite crucibles were used in preference to clay, to prevent the absorption of silicon by the aluminum, as found by previous workers. The melted materials were stirred thoroughly with pine sticks in order to ensure complete mixing and the greatest possible freedom from oxidation, and were cast in sectional, iron molds giving bars % in. in diameter and 5 in. long.

Jan 1, 1927

By R. C. Courtney, D. J. Forrester

Modern advances have led to sweep and multibeam bathymetric surveying techniques that yield three-dimensional images of the sea floor and have also produced high-powered personal computers with which to control the data and analyse the results. At Sydney, in Nova Scotia, the topography of the sea floor over the longwall workings was observed before and after mining with a precision echo-sounder in 1987-89, with sweep bathymetry in 1993 and with multibeam bathymetry in 1994-95. The results of the latter programme produced what was probably the first observation of a complete three-dimensional subsidence trough over a longwall panel 2 500 m x 168 m. The subsidence has been quantified to a sufficient degree of accuracy to allow simple trend analysis, which has shown that the pattern and shape of movements are similar to those found elsewhere but with significantly smaller maximum subsidence. A prediction model has been calibrated

Jun 19, 1905

By T R. Meng, C Wu

After carrying out a brief review of the existing safety assessment criteria for the spontaneous detonation of explosives in the mining of sulphide ore deposits in China, and giving a detailed description of the dynamic process and mechanism of the spontaneous detonation of explosives and the relative factors, the latest research results of three kinds of explosives reacting with a group of sulphide ores are presented, based on a reliable experimental method. Afterwards, a complete safety criterion for spontaneous detonation assessment, which depends on the hole temperature, the water solution Fe2+ and Fe3+ and the pH value, is established to determine (he safe charging time of explosives in variable conditions. The criterion is verified as correct by a large-scale field test.

Jan 10, 1996

L. D. GODSHALL, Everett, Washington: This very interesting paper cannot fail to command the attention of every one who has ever had experience in the amalgamation of gold-ores. I wish to call attention to three very important facts brought out very prominently by the paper, namely: 1. The extent of accumulation of amalgam on copper plates in the form of scale, not removable in the ordinary manner; 2. The change in the relative quantity of the two metals in the amalgam as we. recede from the battery-discharge; 3. The difference in fineness of the bullion obtained from the above-mentioned scale as compared with the bullion from the daily clean-ups. From Mr. Bayliss's figures we find that during the life of the plate in question 14,942 tons of ore were crushed, yielding amalgam of the value of $5.03 per ton, or a total value of $75,158.26. The amalgam accumulating on the plate during this time as scale, we find to have had a value of $8340.54, or $0.558 per ton of ore treated, representing 11.09 per cent. of the total amount of amalgam saved in the ordinary clean-up; or, taking the amalgam saved by daily clean-up plus the amalgam-scale as representing the total saved on this plate, or 100 per cent., we find that the daily clean-up saved 90.01 per cent., while the scale represented 9.99 per cent. The above figures do not include some additional amalgam still adhering to the plate after scale had been removed. We are told that this was not an exceptional case at the Drum Lummon, but that other plates have even yielded a third more than the one in question. The interesting query now comes up, whether this experience at the Drum Lummon is exceptional or universal at all mills; and another question arises, as to how long such an accumulation might continue,

Jan 1, 1897

By Ken Witherly

Modern airborne EM surveys typically acquire more data than is processed or analyzed at the time of acquisition Suitable additional processing can provide more diagnostic information, thereby allowing for more effective ranking and hopefully, follow-up of outcomes

Apr 1, 2005

By Doug Smith, Ross MacFarlane

"The Star Lake Mill was commissioned by Cameco (formerly Saskatchewan Mining Development Corporation) in 1986 to process a small high grade gold deposit in a remote location of Northern Saskatchewan. The lean approach to the 200 t. p. d. CIP mill to minimize capital and operating costs employs a number of unique features which are described along with highlights from the initial two years of operation.1.0 INTRODUCTIONThe Star Lake Mine is located 520 kilometers north of the City of Saskatoon (Fig. l) with the nearest population centre in La Ronge 130 km to the south. Gold showings were first discovered in the area in the 1940's with the Star Lake ""21 Zone"" ore body discovered in 1983. The Star Lake Mine started operations in 1986 becoming the first primary gold producer in Saskatchewan in over 40 years. The mine is operated by Cameco (formerly SMOC) with 50\ ownership in a joint venture with starrex Mining Corporation (35\) and Uranerz Exploration and Mining (15%).The limited reserves coupled with the remote location and the price of gold ($300-$350 u.s./oz) at the time the project feasibility was being assessed required a lean approach to make the short term operation successful. This paper describes the approach taken in the design and construction of the Star Lake Mill and describes the mill operation with highlights of the initial two years of operation."

Jan 1, 1989

By R. T. Jones

DC arc furnaces are widely used for steel scrap melting as well as for reductive smelting of ore fines. Industrial smelting applications include the smelting of chromite to produce ferrochromium, the smelting of ilmenite to produce titania slag and pig iron, and the recovery of cobalt from nonferrous smelter slags. A number of myths and misconceptions are widely held, especially regarding: the age of the technology, the use of a hollow electrode, arc stability and shape, arc and bath radiation, interaction between the arc and molten slag, electrical behaviour of arcs and slags, a comparison between AC and DC furnaces, DC reactors, the lifespan of bottom electrodes, and the applicability of DC arc furnaces to various metallurgical systems.

Jan 1, 2011

By P. C. Carrasco

Knowing the origin of the relevant and irrelevant components of the nugget effect is essential to optimize the process under study. This paper describes the causes of the nugget effect and, its dependency on the sample support, sampling density, and on the QA/QC procedures. Several examples of natural and ?human? nugget effect are given. A method to estimate the magnitude of the relevant and irrelevant components is suggested. Finally, the economic consequences of misunderstanding the nugget effect are analysed.

Jan 1, 2010

By I. C. Spangenberg

The status of sampling practices in the gold mining industry in Africa was determined as an initial step in a process to standardize sampling practices in the mining industry. Twenty-one gold mines, twenty metallurgical plants, and thirteen laboratories were rated for the potential influence of the relevant sampling errors on each component of the particular sampling system. The findings of the study on the status of equipment, standards, procedures, and management principles were presented in a dissertation (Spangenberg, 20121) and are now used by AngloGold Ashanti?s mines in the quest for correct sampling practices. The information is also used to compile a guideline on leading practice procedures for sampling methods in gold mining. This article is an overview of sampling best practice found in African mining Keywords theory of sampling, best practise, sampling errors, sampling standards.

Jan 1, 2014

By B. Anameric, S. Kawatra

Pig iron nuggets, which have similar chemical and physical properties with blast furnace pig iron, were produced by a single step heat treatment of self reducing – fluxing dried greenballs. During this single step heat treatment the transformation of self reducing fluxing dried greenballs into pig iron nuggets did not take place instantaneously. Rather, it was composed of three transformation stages, (1) transformation of self reducing – fluxing dried greenballs into direct reduced iron (DRI), (2) transformation of DRI into transition direct reduced iron (TDRI), and (3) transformation of TDRI into pig iron nuggets. Thus, the objective of this research was to investigate these transformation mechanisms by analyzing the transformation stage products. The transformation stage products were produced at a constant furnace temperature of 1425°C and various furnace residence times. They were characterized according to their microstructure, microhardness and apparent density. The changes in the product’s physical and chemical properties with furnace residence time were utilized in understanding the transformation behavior, the chemical events that took place and the controlling mechanisms. It was determined that the transformations were dictated by the changes in the slag viscosity and wetting properties, and by carbon diffusion into metallized areas.

Jan 1, 2007