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By G. Bylapudi, A. Bhagwat, K. Mondal, A. J. S. (Sam) Spearing

Minimizing the effects of corrosion improves the long-term performance of the rock anchors and ground control systems in underground mines, which is fundamental for safe operation over the design period. The primary objective of this study is to explain the problems due to stress corrosion cracking (SCC), strain-induced corrosion cracking (SICC) and other forms of corrosion, and why the mining industry’s ground control professionals should take this into serious consideration. It is important to clearly determine the kind of SCC mechanisms that causes roof bolt failures in order to suggest the necessary action plan to mitigate or eliminate the possibility of the cause. Pertinent literature and studies around the globe on this complicated subject are reviewed. The secondary objective is to encourage the use of corrosion-resistant ground control products in the underground mining industry in areas of high corrosion potential. Characteristics of SCC on high strength steel are also reviewed. The literature and preliminary studies to date indicate that research work is necessary in United States.

Jan 1, 2015

By R. D. Westervelt

IN JULY 1954, the first iron ore from the deposits in the Knob Lake vicinity was mined and shipped to Seven Islands. The beginning of the production may well be the greatest advance in Canadian economy in the past fifty years. In 1955, the Canadian iron ore output was more than twice that of 1954, an in-crease due principally to the iron ore shipments from the Knob Lake area. Previous to this, Canada's iron production was 1.85 per cent of the world's output. Now, this percentage has risen to approximately 5.5 per cent and shows every indication of increasing further as the production rate from the area is increased. In 1955 the Iron Ore Company of Canada shipped over 7 million tons of iron ore and expects to ship over 10 million tons in 1956. Present facilities may be enlarged to handle up to 20 million tons per year. If the expected I 0 million tons per year are exported, Canada's iron exports will be second only to her wheat and newsprint exports. Before production began from the Knob Lake deposits, years of development were necessary in the area. Geologists spent several summers mapping the general area in order to unravel the complicated stratigraphy and petrology. Particular attention was paid to the mapping of the iron formation and all stages of alteration from fresh iron formation to ore were observed.

Jan 1, 1957

By J. G. Donaldson

Binary alloys of molybdenum and tungsten were prepared by the Bureau of Mines in laboratory-scale experiments by hydrogen reduction of their vaporized hexafluorides. Near-optimum deposition parameters were determined, and the nature of the deposited alloys was investigated. Dense, homogeneous alloys were codeposited between 650° and 750° C with a reduction efficiency of more than 75 percent. The alloy composition was uniform when the hydrogen ratio in the gas feed mixture did not exceed 3 times the stoichiometric requirement. Regulating the proportions of the metal hexafluorides in the gas feed provided a large degree of control over the composition of the deposit. Hardness of the deposits varied directly with the proportion of excess hydro,,,, in the gas feed and with the weight-percent of tungsten in the alloy. Hardness was not affected by deposition temperature over the range 650° to 750° C for specimens of similar composition. Extreme brittleness and unsuitable physical shapes of the alloys prevented tensile strength measurements.

Jan 1, 1966

This paper presents the results of an experimental study undertaken to demonstrate the feasibility of using silica sand as a grinding media in stirred ball mills for ultra-fine coal grinding. Laboratory batch as well as bench scale continuous tests indicate that the use of silica sand can reduce the energy consumption by 50% and more over its steel media counter-part. Moreover, this approach has been found to eliminate the disadvantages observed with grinding using steel media such as high replacement cost, contamination of coal through media wear, greater degree of coal oxidation due to higher slurry temperature and greater level of noise dissipation. Additionally, coal-sand attrition system reduces the manpower time required which is often spent towards cleaning and storing of steel media in inert atmosphere to avoid rust and corrosion problems.

Jan 1, 1991

By T. W. Turk, S. A. Sass

The engineering design features of the Mercur Gold Project crushing, grinding, carbon-in-leach, bullion, reagent, and tailings disposal areas will be discussed in this paper. It presents a project overview and flowsheet along with selected design alternatives. During the engineering phase, major equipment and other features were selected to optimize design within site location and environmental constraints. The project team organization and procedures were adopted to accommodate multiple optimization studies while maintaining a tight engineering schedule.

Jan 1, 1985

By W Akpan

The Royal Bafokeng community in South AfricaÆs North West Province represents a unique case in Sub-Saharan Africa in terms of its positioning in the natural resource economy. It receives royalties directly from mining firms for the extraction of Platinum Group Metals, which include platinum, ferrochrome, rhodium and palladium. In 2007, royalty income of about R290 million (approximately US$32.2 million) was reported. Such direct revenues have enabled the community to invest in educational, medical and other social infrastructure, thus complementing governmentÆs social provisioning efforts. Indeed, the Bafokeng community owes its present-day modernisation efforts to mineral rights, and in particular, the legal-institutional arrangement that has enabled it to play an active role in South AfricaÆs lucrative extractive economy. However, the distribution of platinum wealth in this community is not only uneven, but also appears to have had little impact on the broader socio-economic conditions in the community. Despite claims by community leaders of heavy investment in education and skills development, the community continues to be faced with very high levels of unemployment, illiteracy, sprawling informal settlements, poor access to medical facilities and malnutrition. This paper examines the sociological paradoxes and contradictions thrown up by the approach adopted to involve community members in the mobilisation of mining royalties for developmental ends. The central argument is that the current æmodelÆ contradicts the communityÆs stated goals of using platinum wealth to drive up broad-based development and modernisation. This is mainly because it leaves out the vast majority of community members, who are uneducated and unskilled. The core analysis is based on pilot data from an ongoing study in the Royal Bafokeng community.

Jan 1, 2009

By Thiago Figueiredo Azevedo

Ligas de titânio e nióbio têm sido desenvolvidas devido a possibilidade de modificar as propriedades mecânicas por envelhecimento. No presente estudo ligas TiNb com diferentes concentrações de Nb e com adição de estanho foram obtidas por fusão a vácuo, deformadas a frio e posteriormente tratadas por diferentes tempos de envelhecimento. Foi observado que todas as ligas em todas as condições apresentam as mesmas fases ß, a” e ?, no entanto, apresentam diferentes microestruturas. Isso se refletiu nas propriedades mecânicas das ligas, onde obtevese maiores durezas com o envelhecimento em 48 horas em todas as ligas, esse aumento de dureza foi quase o dobro para as ligas com maiores teores de nióbio (Ti42Nb e Ti42Nb2Sn).

Aug 16, 2017

By C. P. Snyman

Three independent methods of coal classification can be distinguished, namely on the basis of grade, type and rank. The latter two can be determined accurately and unambiguously only by means of microscopical techniques. These three independent variables affect all the coal properties and therefore also the technological behaviour of a particular coal. The influence of the inorganic constituents of coal on the fusibility of the ash and on the length of the slag, and also on fouling and slagging, is discussed. The fractionation of the ash-forming constituents during combustion and gasification of pulverised coal shows that fouling and slagging are not related directly to the fusibility and composition of ash of the coal as a whole. The results of combustion experiments using a drop furnace technique indicate that the ignition temperatures of the light volatiles in the coal, and of the formed char, as well as the burn-out time of the char are more dependent on the rank than on the type or grade of the original coal. High-ash coals, however, apparently ignite at lower temperatures and are more reactive than low-ash coals of similar type and rank. The surface properties of coal, which are important in froth flotation and oil agglomeration, correlate well with the inherent moisture content (and by inference with the heat of wetting and the calorific value) and therefore with the type and rank of the coal. In coal exploration, variations of rank offer the possibility of predicting the presence of an intrusion near the seam, thus contributing to more effective exploration and mine planning.

Jan 1, 1991

By Henrique Silva Furtado, Flaviani Marculano Marchesi, Silas Gambarine Soares, Elton Volkers do Espírito Santo, Felipe Fardin Grillo, Heitor Cristo Clem de Oliveira

Devido ao aumento da restrição do teor de enxofre nos aços torna-se necessário investigar a eficiência do processo de dessulfuração de ferro gusa. Portanto, o objetivo deste trabalho é empregar diferentes matérias-primas e fundentes como cal calcítica, sodalita, pré-cal, mistura padrão, fluorita, escória de KR, borra de alumínio e B2O3, a fim de encontrar a composição com maior eficiência de dessulfuração, relacionando-a ao fator de dessulfuração, obtido pela termodinâmica computacional. Os testes foram realizados a 1350°C, em uma atmosfera inerte com agitação constante. Os resultados mostraram que a mistura com maior eficiência foi aquela com 69% de cal, 5% de sodalita, 15% de pré-cal, 6% de escória KR e 5% de B2O3.

Oct 1, 2019

By W. R. McClelland

GOLD-BEARING ores, representing many types, are found widely distributed through the Province of British Columbia. They range from those which by their nature may be considered as complex, to those whose mineral characteristics are simple. Those in which the gold is associated with metallic sulphides provide particular milling and metallurgical problems, the solution of which involves not only detailed laboratory investigation but also a careful consideration of economic factors. The location of an ore-body may have a deciding influence on the adoption of a method for the metallurgical treatment. Whether the ore should be treated with the object of recovering the gold as bullion or as a shipping concentrate is often dependent on such topographical considerations as the position of the mine at or near tidewater or within a reasonable overland distance of a smelter. British Columbia is fortunate in having the Trail smelter situated in the southern part of the Province, and the smelter at Tacoma, Washington, is accessible for coastwise traffic. Both of these provide a ready market for most types of gold-bearing concentrate. In order that the results obtained by laboratory tests may give a fair indication of what should follow in mill operation, it is essential that the test sample should represent as closely as possible in mineralogical character and in grade the ore that eventually will constitute the feed to the mill. In the early stages of mine development this consideration is sometimes overlooked and samples of a much higher grade than would be representative of run-of-mine ore are submitted. Flotation tests on such a sample of ore high in sulphides may show a low ratio of concentration, bu.t if the actual run-of-mine ore is lower in sulphides the mill operation will reveal a much higher ratio. The recommendations for treatment based on the results of laboratory tests may have been against concentration, when in actual operation this would be the most suitable method of treatment. Recommendations based on laboratory tests are necessarily from the results of work carried out on the sample submitted, modified only by such other economic or topographical information as may be known to the investigator. This paper deals with a few of the gold ores found in the six mining districts of British Columbia and is based on investigations made in the Ore Dressing and Metallurgical Laboratories of the Mines Branch, Department of Mines, Ottawa.

Jan 1, 1937

By Euler De Souza

"Underground operation ventilation energy requirements constitute a significant portion of mine energy consumption (40–50%) and total energy costs (25–40%). In general, mine ventilation systems are energy inefficient; the author has found several systems that operate at efficiencies below 65%. This paper presents how engineering design principles can improve the performance and efficiency of ventilation appliances, resulting in reduced power consumption and operating costs. Case studies demonstrate that, by retrofitting ventilation appliances using proper engineering concepts, systems will operate at efficiencies well above common operating efficiencies, resulting in a drastic reduction in costs and base electrical and energy loads.RÉSUMÉ Les besoins énergétiques nécessaires à l’aérage d’une exploitation souterraine représentent une part considérable de la consommation d’énergie d’une mine (de 40 à 50 %) ainsi que des coûts totaux liés à l’énergie (de 25 à 40 %). De manière générale, les systèmes d’aérage d’une mine sont loin d’être écoénergétiques ; l’auteur a trouvé plusieurs systèmes fonctionnant à des rendements inférieurs à 65 %. Cet article présente les principes de conception technique qui peuvent améliorer la performance et l’efficacité des systèmes d’aérage, entraînant une réduction de la consommation d’électricité et des coûts d’exploitation. Des études de cas montrent qu’en les rénovant à l’aide de concepts techniques adéquats, les systèmes d’aérage fonctionneront à des rendements bien supérieurs aux rendements habituels d’une exploitation. Ces rénovations donneront lieu à une réduction considérable des coûts ainsi que des charges électriques et énergétiques de base.INTRODUCTIONIncreasing electricity supply problems in North America have encouraged an industry-wide evaluation of energy consumption, resulting in a more urgent emphasis on energy-efficient design and operation for all energy-consuming systems. Electricity is the main mode of energy supply and the mining industry is affected by the increasing cost of this commodity (Natural Resources Canada, 2017). Ventilation systems normally operate 24 hours per day, 365 days per year, and account for 25–40% of the total energy costs and 40–50% of the electrical consumption of a mine operation (De Souza, 2013). Ventilation engineers are under ever-increasing pressure to reduce ventilation energy consumption and be cost effective."

Jan 1, 2018

By W. A. McKinney

A sample of oxidized copper ore from a large deposit located in Pinal County, Ariz., about 50 miles northeast of Tucson, was treated by the Federal Bureau of Mines in a small-scale continuous pilot plant by a procedure which comprised acid curing complemented by water leaching and countercurrent decantation washing in a series of drag classifiers. A feed was prepared by pugging minus 1/4-in, ore with concentrated sulfuric acid and about 10 pct, of eater, followed by curing in batches for about 24 hr. The cured ore was fed continuously to a leach drum, where it was mixed with advance solution from the countercurrent washing system to dissolve the sulfated copper. The pulp was thickened and washed in four Esperanza-type classifiers, using a flocculating agent to obtain rapid settling and thickening. The leached ore pulps thickened satisfactorily in the drag classifiers when about 0.8 lb. of a polyacrylamide flocculant per ton of dry feed was used. Clear overflow liquors were obtained, and classifier rake products containing about 60 pct. solids were produced, As much as 90 lb./hr. of ore was treated in the plant, with a recovery of 60 pct. of the total copper or 80 pct, of the acid-soluble copper when 2 tons of water per ton of feed was used in washing. The acid consumption was 4.3 lb./lb. of copper recovered. On the basis of the maximum feed rate employed and the effective pulp-settling area of the classifiers, a total of 1 sq. ft. of pool area was required per ton of dry feed per day for the thickening and washing operations. The washing efficiency in the test was 95 pct.

Jan 1, 1960

By N. M. Levine

This work defines and systematizes the physical factors of the problem of leaching and demonstrates for the first time the utility of macropore volume, micropore volume, specific surface, pore size distribution and permeability as parameters of leaching based on a study of the recovery of uranium from the Top Black member of Chattanooga Shale.

Jan 1, 1962

By K. A. Johnson, H. F. Yancey

"INTRODUCTION Coals vary so widely in their burning characteristics that all coals prepared for domestic stoker use cannot be burned efficiently on every type of stoker. The overfeed stoker, a large number of which are in use in the Pacific Northwest, operates satisfactorily when burning low- to high-ash, noncaking bituminous or subbituminous coals, whereas on the clinkering-type, underfeed, bituminous stoker both caking and noncaking bituminous and subbituminous coals are burned, generally with ash contents below 12 percent and ash-softening temperatures between 1,800º and about 2,600º F. Because fly ash continues to be one of the most troublesome factors in domestic underfeed stokers, noncaking coals especially must be chosen carefully with respect to size composition, particularly as regards the exclusion of excessive fines. Their formation as a result of degradation in storage handling or because of crushing in .the stoker worm will increase the fly-ash nuisence.Bituminous and subbituminous coals with higher ash-softening temperatures and, often, higher ash contents have not been able to enter the domestic stoker-coal market in the Pacific northwest because clinkers are not formed readily during clinker-type underfeed-stoker burning, especially in mild weather, and because of the labor and attendant inconvenience required in handling larger volumes of ash. The work described in this report was undertaken to enable mines producing coals of the kind described to enter the stoker-coal markets. The anthracite stoker selected was one that conveys the refuse from the ash pit of the furnace and deposits it into one of two covered, dust-tight disposal cans."

Dec 1, 1945

By J. E. Udd, S. Bharti

"ABSTRACTMonitoring of stability conditions in underground mines permits management to assess the response of the rock mass to mining strategies. Monitoring of movements, if sufficiently early, may also permit operators either to avert potential failures or to develop alternative approaches to extraction.The Falconbridge organization has been a leader both in the uses of rock mass stability monitoring techniques and in the development of instrumentation.In this paper, the authors review the Falconbridge approaches to monitoring, and present case history examples to illustrate the application of the various instruments used.RESUMELa surveillance des conditions de stabilité dans les mines souter-raines permet aux chefs d'enterprises d'évaluer les réactions de la masse rocheuse aux méthodes d'extraction minière. Si le contrôle des mouvements du terrain est effectué assez tot, l'exploitant pourra prendre les mesures qui s'imposent, soit pour éviter les détériorations possibles ou pour mettre au point de nouvelles méthodes d'extraction.Le groupe de la Falconbridge a ére le premier a utiliser des techniques de vérification des conditions de stabilité de la masse rocheuse et a mettre au point l'appareillage requis.Ce document présente une revue des méthodes employées par la Falconbridge pour assurer la surveillance active de la stabilité de la masse rocheuse et illustre au moyen de cas concrets la manière d'utiliser les divers appareils."

Jan 1, 1987

By Stephen Darmawan, Mahdi M. Disfani, Arul Arulrajah, Alireza Mohammadinia

Deep mixing using cementitious compounds is an in-situ method of ground improvement for improving the strength, compressibility of loose sand. Artificial light cementation can increase the stiffness of loose sands significantly and reduce the settlement of loose deposits. The increase in contact area between the particles with a thin layer of cementitious agent depends on the confinement and void ratio of the soil mass. Hence, the stiffening effect of cementation not only depends on the type and amount of cementing agent and inter-particular force chain of loose deposit but also depends on the stress level at the time of cementation. In addition, the cementation effect in loose deposits can be deteriorated at relatively low strain levels. Decementation softening can cause detrimental and irreversible impacts on the soil deposit. This study investigates the effect of initial confinement and subsequently the initial void ratio at the time of cementation on small strain behaviour and decementation softening of cemented loose sand under ko loading. The effect of inter-particular contact of sand particles based on the specific surface area and also soil density was also investigated by means of shear wave propagation. This study present insightful information on effect of primary consolidation stress levels, density of soil and cementation level on softening and collapse of loose deposits improved using deep soil mixing technique. Better understanding of soil-cement interaction by optimization of binder content for deep mixing activation can lead to increasing the level of confidence in using this technique in ground improvement applications.

Jan 1, 1900

By Marcus Digre

The autogenous grinding method has been progressively employed in mineral dressing plants during the last 15 years. The term has been used with somewhat different meanings (1), (2), (3). In this paper the author will use it in the most restricted way, for processes where run-of-mine ore (rock) in one step is reduced to a grind product by the action of the ore itself without any other grinding media present. The pebble grinding process where the major part of the ore enters the mill as finely crushed product which is ground further with selected coarse ore pieces acting as grinding media, is not considered autogenous grinding. Processes where a minor amount extraneous media as steel-balls is added to supplement an autogenous mill charge will be called semiautogenous. Other terms need also to be defined. "Mill charge" will be used about the active part of the mill content which performs the grinding, that is the steel balls in ball grinding and the coarse ore pieces in pebble and autogenous grinding. The interstitial nearly finished material is not included in the term "mill charge", and for the wet grinding operations is called the "mill pulp' The term "pebble" will be used for any rounded ore or rock piece in the mill charge whether it is an autogenous or a pebble grinding operation.

Jan 1, 1970

By Gary G. Grim

The reliable performance of the coal reclaim system is essential to the continued availability of a coal-fired electric generating unit. The control of fugitive coal dust within the areas housing the reclaiming equipment is necessary not only to minimize maintenance and clean-up costs, but is also a safety and health consideration. This paper describes the reclaim system control and dust suppression systems as initially installed, the shortcomings of these systems and the steps eventually taken to correct these shortcomings.

Jan 1, 1983

By James M. Peay

This paper discusses the recently completed organizational development research project, which was addressed to the underground mining industry. The three specific purposes of the project were as follows: (a) to determine whether Organizational Development approaches are feasible in the mining industry, (b) to provide a demonstration that Organizational Development methods can successfully contribute to the safety of underground mines, and (c) to compare the efficacy of classical Organizational Development methods, which are highly trainer- intensive, with trainer-nonintensive management development approaches. The term "Organizational Development" (OD) is here broadly defined as a management intervention for the purpose of assisting an organization with the solution of problems, which are seen by the organization as important. More specifically, we can define OD as a planned effort to improve the effectiveness of an organization through (a) team building and problem solving, which concentrates on the issues of immediate concern to the organization, and (b) efforts to improve organizational communication at all levels of the organization.

Jan 1, 1983

By Viviam Serra Marques Pereira

Aços ARBL são utilizados na fabricação de tubos para transporte de gás natural e petróleo e, devido ao ambiente agressivo, rico em H2S, em que são aplicados, devem resistir à fragilização por hidrogênio. No presente trabalho, verificou-se qual a influência do alongamento longitudinal dos grãos de um aço API X65, com baixo Mn, sobre a permeabilidade de hidrogênio. O material foi caracterizado com a utilização dos microscópios óptico e eletrônico de varredura e os ensaios de permeabilidade foram conduzidos com base na norma ASTM G 148-97. A microestrutura do aço era composta por ferrita e perlita, com baixo teor de inclusões arredondadas de Al e Ca e sem bandeamento. Com os resultados obtidos a partir dos ensaios de permeabilidade, calcularam-se os coeficientes de difusão efetiva do hidrogênio nas seções longitudinal e transversal do aço, e o valor do primeiro se mostrou levemente superior ao do segundo. Isto indica que pode haver influência do alongamento longitudinal dos grãos sobre a permeabilidade de hidrogênio.

Aug 16, 2017