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By Jorge Alberto Soares Tenório, Marcela dos Passos Galluzzi Baltazar, Lidiane Maria de Andrade, Márcio de Morais Tavares, Denise Crocce Romano Espinosa, Bruno Karolski

A contaminação de solos e do ambiente hídrico por hidrocarbonetos de cadeias longas, geralmente por rompimentos de dutos ou por acidentes ocorridos no seu transporte afetam o meio ambiente de forma deletéria. Visando aplicabilidades futuras na remediação de solos e águas, existe a necessidade de estudos de biodegradação específicos, como por exemplo, bactérias que utilizam óleos de cadeias longas como fonte de carbono, visando melhorar o entendimento do mecanismo de interação do óleo com as bactérias. Baseado neste raciocínio, para desenvolvimento deste trabalho que visou encontrar, estudar e entender o metabolismo de uma microbiota capaz de utilizar hidrocarbonetos de cadeias longas como fonte de carbono, foram isoladas linhagens de bactérias provenientes de uma comunidade encontrada em borra de petróleo. Esta comunidade bacteriana teve avaliado seu poder de biodegradação de várias moléculas, constituintes do petróleo, assim como a sua preferência metabólica por cadeias específicas, resultando em um melhor entendimento do processamento dos componentes do óleo derivado de petróleo por micro-organismos. Os resultados de cromatografia comprovaram a biodegradação através da redução dos picos, e através do estudo dos cromatogramas foi possível identificar as substâncias biodegradadas.

Mar 1, 2019

By S. Z. Galiyev

In this paper the basic approach to the present planning and quality management of open-pit ore streams is presented. This is accomplished within the framework of a unified system of information management for the administration of a geotechnological complex on open-pit development of mineral deposits.

Jan 1, 2003

By R. A. Wyman

The overall approach to nonmetallic mineral flotation practiced in the laboratories of the Mines Branch, Ottawa, Canada, is outlined. The use of floatability tests to indicate possible areas of selectivity is indicated. Selected examples of the evolution of flotation systems are presented. Reagents are briefly discussed.

Jan 1, 1972

By Martial P. Corriveau

Almost everyone agrees that coal and oil shale are the only fossil fuel resources in which the United States is self-sufficient. Of the two, only coal has a technology sufficiently developed to be of intermediate term benefit. Since it takes at least 20 years to bring advanced technology into practice, it seems logical that the major focus on energy developments should be aimed at coal. Meanwhile, we need to trade-off between actions to meet our immediate needs and the various political regulations and social demands that are disrupting the coal industry and the industries dependent upon it. The largest single user of coal is the electric power generation industry. Over 300 million tons of coal are presently being consumed each year. In view of the 5-to 7-years lead time to bring in a base-load fossil-fuel fired generating station, our requirements for double this tonnage in 1980 are already well forecast; that is, if the coal companies are allowed to mine and the utilities are allowed to burn the coal.

Jan 2, 1974

By H. Knorre, A. Griffiths, R. Higgins, S. Gos

Hydrogen peroxide is gaining acceptance as a reagent for the treatment of mining effluents containing cyanide. In this paper some of the chemical and environmental aspects of treatment with hydrogen peroxide are discussed, and one way of improving the economics of the process is described. This is known as selective detoxification, which involves the oxidation of the less stable (cyanide) complexes while not affecting the more stable complexes, which contribute very little to the concentration of free cyanide or to the toxicity of the treated water.

Jan 1, 1987

By P. R. Hervey, J. W. Foise

Quartz is the second most widely used electronic material, with approximately 3,000 t (3,300 st) of single crystals used each year. Most of the quartz used in electronics is synthetic and is manufactured using a technique called hydrothermal growth. This paper reviews the basics of hydrothermal growth, the feedstocks used for these crystals and the challenges to improving the growth process. This paper also reviews the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 2002

By R. P. Carreker, R. L. Fullman, J. C. Fisher

CREEP tests are usually constant load tests. As deformation occurs, the cross section of the specimen changes so as to maintain approximately constant volume. Until necking starts, A _ l0 A0 - 1 where A is the cross-sectional area, 1 is the specimen length, and the subscript o indicates initial values. Thus, during a tensile creep test under constant load, the stress increases in proportion to the elongation. A A, 1, where S is the stress and F the load applied to the specimen.

Jan 1, 1954

Sustainable Development SAFETY ?Safety is the most important element of sustainability. ?One bad experience or incident can mar a company?s reputation for a long, long time. ?News travels faster than ever ?Internet, blogs, texting, peer-to-peer communication, etc. and unfortunately sometimes the information is not always accurate. ?Rarely do we hear in the news about the mining companies or projects that are done safely ?we always hear about the exceptions. ?Safety is just like TQI / TQM ?the process of improving can never stop.

May 1, 2010

By Frédéric Flament, Daniel Hodouin, Claude Bazin

A control strategy is proposed to meet the following specifications of flotation control: minimize the variations of concentrate and tails grades and recovery while limiting the amplitude of variations of the manipulated variables. The strategy consists of determining future control actions which optimize a performance criterion over a limited time horizon. The desired dynamic behaviour of the controlled flotation plant is specified using reference models. The strategy is tested on a 2-computer plant simulator working in an environment which emulates the industrial conditions.

Jan 1, 1993

By S A. Johnson, J Cassidy, J L. Mauk

Geophysical anomalies at Puhipuhi reflect both diverse lithologies and different degrees of hydrothermal alteration. Most significant is a strong negative gravity anomaly (up to 50 g.u.), encompassing but extending beyond areas of known alteration, which is modelled as a deep zone (up to 3 km) of reduced density in the host greywacke basement. This zone, interpreted as being due to alteration (at least in part), closely correlates with the extent of overlying basalt flows. The gravity data indicate that the most intense alteration occurs below the basalts and correlates with the location of previously inferred hydrothermal upflow zones. These observations suggest that the basalt may have acted as a cap rock to a mineralising geothermal system. Aeromagnetic data identify highly variable but typically low magnetisations in the basalts which suggests that alteration may have been contemporaneous with volcanism. These geophysical data at Puhipuhi confirm the locations of centres of known alteration and suggest potential exploration targets below the basalt cap where there is no surface manifestation of alteration. Further implications of these results are discussed in Locke et al. (1999).

Jan 1, 1999

The most critical step in the development of any mining project is the completion of a feasibility study. The feasibility study has one primary goal; to demonstrate that the project is economically viable if it is designed, constructed and operated in accordance with the concepts set forth in the study. Starting from a mineral resource data base, the feasibility study will define the ore reserves, the mining methods, the mineral processing concepts and the scale of the project. The disciplined activity of developing a feasibility study leads the proponent to examine every aspect of the project, many of which might otherwise be ignored. All technical concepts will be established and the corporate philosophy with respect to organisational structure, social and environmental responsibility, infrastructure contributions and financing will be determined. All the major decisions about how the project will be developed are made during the feasibility study. The success of the project will then depend upon the assumptions and decisions in the feasibility study and the ability and empowerment of the development team.

Jan 1, 1997

By Bobby J. Timmons

A few years ago during a Southeastern Geological Society field trip, a professor from a Florida university and a trip leader commented at one of the stops, "... and for those of you interested in the geology ...." More recently, in the spring of 1992, a geology faculty member at another southeastern university remarked, "Field geology is obsolete." An interviewee for a potential assistant position stated that he had never had a field class. This would-be assistant was to receive his Master's Degree in-Geology within a few days from yet another southeastern university. A regional illness? Certainly not, but symptomatic of the general health of Geology. Capitulation to Environmental Sciences seems to be in vogue with Geology becoming a four-letter word and the mention of mining is verboten regardless of the company. These trends permeate our profession while the demands for earth materials increase, often exponentially. Efficiency, a word lost on government, is routinely expected of business--our business--the industrial minerals geologist and producer. Our stage shrinks but the responsibilities expand. Are we meeting the challenge? Stay tuned!

Jan 1, 1995

By K. A. Dudley

Basic solvent extraction theory indicates that pH initiates the basis of an oxime's metal complex formation and therefore its selectivity toward certain metal species. The recommended optimum pH for some of the commercial copper reagents is in a range that should maximise copper loading of the oxime. However, this pH range also tends to maximise iron(III) loading under certain operational conditions resulting in low selectivity values. Recent operational parameters at Girilambone Copper Company have highlighted some of these conditions that have a major influence on the oxime's selectivity for copper over iron(III) in the leach solutions. The result is that the pH for maximum copper extraction is no longer within the optimum range to maximise oxime selectivity. Therefore, specific copper and iron(III) pH isotherms have been determined on-site for the changing leach solutions that are fed to the solvent extraction plant in order to optimise oxime selectivity. The influences of solvent extraction plant configurations are also discussed as a controlling parameter.

Jan 1, 1999

By R. M. Raymond

THE Mining Section of The National Safety Council recently sent out a questionnaire to operators, regarding the class of rope used, specifications required or obtained, factors of safety observed, methods of fastening ropes, lubrication, inspection, and points observed when rope is to be discarded. The answers received from this questionnaire, largely from metal mines, give interesting information, from which recommendations for safety practice on hoisting ropes are drawn. DEPTH OF MINE The depth in the majority of cases noted is from 1000 ft. to 1500 ft. (304 to 457 m.) and records come from a number hoisting from depths of 2000 to 3000 ft. Hoisting is generally done in balance, with a few companies using counterweights. Seldom, more than two shifts are occupied in hoisting. A number of large operators limit the shift for engineers to 6 hr. A few of the larger operators have separate hoists for men and supplies, with a higher class rope for men. The range of loads varies from 7 to 17 tons and greater in a few cases, with a balanced weight of 4 to 7 tons.

Jan 2, 1922

By E. D. Peters

The Sudbury ore-deposits possess a peculiar interest for a variety of reasons. In the first place, they are deep within the borders of the Huronian rocks, and are consequently amongst the oldest deposits that we know of, unless, indeed, the ores were deposited at a much later period than the country rock. Again, they carry nickel in unusual proportions, and lastly, they are unique in containing a small amount of platinum, although arsenic is not present. I shall not pretend to go into the geology of this region. The Huronian and Laurentian rocks are familiar to all American geologists, and these present only the usual series of gneiss, graywacke, quartzites, greenstones, clay-slates, etc., characteristic of this gigantic system of rocks, which has excited so much discussion of late years. As in all parts of Canada where it occurs, I believe, the rocks of this system are tilted to such an extraordinary degree that it may be said that the whole country is standing on edge at an angle of something like 70°. The general strike of these rocks is southwest

Jan 1, 1890

By H. Colijn

Belt scales are frequently used in the mining industry because of the ability to handle large tonnages without interrupting the material flow, fitting easily into all types of bulk handling systems and being relatively inexpensive. Although manufacturers claim weighing accuracies better than Y2%, many operators experience, in practice, much larger errors and they have become apprehensive about the use of belt scales. However, in spite of these disappointing instances, a belt scale is one of the most valuable tools for process and inventory control. Since it is a measuring device, care should be given to the design and installation of belt scales. The basic components of a belt scale are: (1) conveyor belt, (2) scale suspension, (3) sensing device, (4) integrating and recording. The first component of this system is of great importance to the overall accuracy and has been thoroughly discussed in earlier papers. This paper will review primarily the various scale hardware designs currently available, and will be confined to the last three components of the system.

Jan 1, 1973

By Mckenzie CK

Delay scatter, although widely recognised, has rarely been studied with the aim of critically reviewing blast designs. With current trends towards increased deck charging, and the effect on the number of separate delays in blast designs, delay scatter is shown to have a rather profound influence on the control of initiation sequence and the ability to successfully con- duct pre-splitting and smooth blasting. Determination of realistic delay scatter distributions is the first step towards application to blast design. Delay scatter must be evaluated in terms of deviation from the nominal time, not in terms of deviation from the batch mean, since the latter is not usually known without specific testing, requiring accurate timing instrumentation. Computer programs using Monte Carlo simulation can then be developed to investigate the probabilities of out-of-sequence initi- ation or near-simultaneous initiation within any specified interval. The procedures have been applied to both production and development blast designs in Australia and Chile to improve initiation sequence control and to rationalise and simplify blast designs.

Jan 1, 1988

One of the key issues facing gold producers is the management of cyanide and the implementation of the International Cyanide Management Code. Many operations now use cyanide destruction processes to ensure that the material being discharged to the tailings dam is compliant with regulatory requirements and the International Cyanide Management Code. One of the problems for operations is the quantification of both cyanide species and their reaction products throughout the leach and destruction circuits. Therefore methods have been developed utilizing high performance liquid chromatography (HPLC) to measure free cyanide, cyanide complexes of metals such as copper and iron, and other species formed from reactions in leaching and cyanide destruction, including cyanate, thiocyanate, and sulphur species (eg. sulphite, thiosulphate and sulphate). This enables a complete mass balance for cyanide and sulphur in both leaching and cyanide destruction. This paper outlines the methodology which has been developed and discusses the application of these methods in the fundamental research currently being conducted on the impact of sulphide minerals in cyanidation and cyanide destruction chemistry.

Jan 1, 2009

By Russell F. M

Following the accident in the Peterson section of Mufulira mine in September, 1970, a method had to be found of extracting up to 300 000 tonnes of ore per month from this area without inducing caving. Sandfill mining methods were chosen, necessitating a plant capable of producing both cemented and uncemented fill on a large scale. The paper covers the design and construction of this sandplant which is thought to be unique for its size, as it incorporates three 3 000 tonne capacity settled storage silos, a 500 tonne capacity cement silo, mixing tanks and a control room situated underground. The plant is designed to handle an aver- age of 440 tonnes per hour with a maximum of 660 tonnes per hour for limited periods, delivering either uncemented fill or cemented fill in proportions varying from 1:6 to 1:30. The instrumentation and equipment necessary to give one man operation of the plant is described and the fill mining methods now in use at Mufulira are briefly outlined.

Jan 1, 1973

By Steve Kral

When discussing stock market investments, a company's performance is important. But so is the financial community's perception of that performance. To be sure, a good product or service, coupled with sound manage¬ment, remains important but is no longer enough. How stock analysts view a company's performance has become equally important. A major task of a mining company's investor relations officer, then, is to build and maintain a positive perception of the company to mining analysts throughout the world. That's a tough assignment in any market. The subject here, though, is gold. And, with its weakened price, gold companies must work harder to convince analysts their company is still a good investment. The analyst, on the other hand, must see through the corporate hype and decide whether it's worth recommending to clients as an investment. No simple task, either. Annual reports, 10-K forms, and quarterly reports only tell part of the mining company's story. Site visits, complete with discussions (sometimes interrogations) with a mine's principals, oftentimes tell an analyst more about a company's investment potential than the annual or quarterly report. So it was that three of the nation's major gold companies arranged a three-day tour of their gold operations in Nevada for a group of 22 analysts and a pair of mining industry scribes. The analysts represented investment houses the US, Canada, and England. The host companies and mines visited included FMC Gold's Paradise Peak mine, Amax Gold's Sleeper and Wind Mountain mines, and Battle Mountain Gold's Surprise and Fortitude mines.

Jan 1, 1989