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By Henry R. Ensminger

Brazil's gross domestic product (GDP) grew only slightly in 1988 to $277 billion at current prices.2 The growth rate was the smallest registered since 1983, when the rate was minus 2.8%. The economy's performance was strongly influenced by a 2% to 3% decrease in industrial production and civil construction. The mineral industry, however, countered the downward trend in the industrial sector and grew a modest 1.4%. In November, Brazil adopted a new Constitution that placed significant restrictions on foreign investment in the mineral industries. Under certain provisions of the new Constitution, foreign companies were prohibited from establishing new mining ventures in Brazil as sole or majority owners. They could now enter the mineral industry only as minority shareholders with Brazilian partners. Foreign companies already established in Brazil had a 4-year grace period to find majority Brazilian partners, or to establish vertically integrated processing operations (mining, processing, smelting, and refining). The new Constitution also prohibited foreign risk contracts for petroleum exploration.

Jan 1, 1990

By C. Abbruzzese, F. Vegliò, S. Ubaldini, R. Massidda

"Gold solubilised during cyanidation can be recovered by precipitation (Merrill-Crow process) or by adsorption onto activated carbon, these being the techniques applied in industrial plants.Precious metals (Au, Ag) adsorbed onto activated carbon are extracted during a subsequent stage in aqueous phase, by various technologies, such as hot elution (70-80°C) or under pression desorption (100-130°), with hydro-alcoholic solutions.This stage is of great interest from an economic point of view, due to the high energy costs. Temperature represents the critical kinetic factor.The aim of this paper was to study the influence of different water/organic solvent mixtures (isopropyl alcohol, ethanol and ethylene glycol) on the desorption process.The experimental work was carried out on laboratory scale, using activated coconut carbon with different temperatures and extraction times, without adding cyanide.Best results have been obtained in this order: isopropyl alcohol > ethylene glycol > ethanol. Starting from gold concentration of about 5 g Au per kg of carbon, best kinetics resulted in 97-100% of gold extraction, after 8 hours of desorption, at a temperature of 80ºC."

Jan 1, 2003

By J. J. Forbes

Ventilation is the most important safety factor in the production of coal because on it depends the safety, health, and efficiency of those who work underground. Without adequate and efficient means of supplying fresh air to the working faces, mining could not have advanced as it has. The extent of the workings, the increase in mechanization, and the increasing use of electricity are largely responsible for changes in methods of ventialtion. Ventilation in the early, days of coal mining was accomplished by means of a natural draft, created principally by a difference in the weights of columns of air between the intake and return openings: Later the furnace was introduced for the purpose of increasing the quantity of air in circulation. Mines continued to become larger, their output increased, men were employed in greater numbers, and more fresh coal surfaces were exposed. Coal beds near the surface, and practically free from explosive gas became exhausted, and deeper beds that liberated methane were opened as development advanced. Mechanical ventilation became necessary and was first accomplished by disc-type steam driven fans she old-.fashioned steam driven disc fan has generally been supplanted by the powerful electrically operated centrifugal fans in use at modern coal mines. In order to be secure against gas explosions and provide ample fresh air for persons employed in large coal mines, air must be conducted through the mine to all working places and to all other unsealed parts of the mince in sufficient quantities to dilute and render harmless all dangerous and noxious gases.

Jan 1, 1929

By T. S. Golosinski

The paper reviews current status of online education related to mining, and reports on the online Master of Engineering programme in Mining Engineering that is offered at the University of Missouri-Rolla since 2001. Keywords: Online education, learning, teaching, mining engineering, mining education online

Jan 1, 2003

By C. V. Baltzer, E. L. J. Bingham

Compliance with the EPA's emerging Clean Water Act regulations can be challenging. Open pit copper mines in Arizona have found themselves in a tangled web of changing rules, regulations, and guidance documents regarding storm water and process water discharges. Large mining properties must come up to speed on a myriad of issues including the definition of zero discharge, what constitutes a process related spring or seep, and tailings and waste rock Best Management Practices. The example of the Pinto Valley Mine in Arizona is used to illustrate National Pollution Discharge Elimination System regulatory issues.

Jan 1, 2001

By A. V. S. Meyer

The Colloquium held at Iscor, Pretoria, on 28th June, 1988, had as its objective the need for Quality Management Systems in the industry. Case studies of how problems were identified and solved by the use of such systems were submitted.

Jan 1, 1988

By D. G. C. Robertson

The thermodynamics and kinetics of the reactions involved in fuming zinc from oxide slags using coal or coke were first studied in 1955 and have been the subject of many investigations since that time. The key reaction is ZnO(in slag) + CO = Zn(g) + CO2 This paper will review the some of the recent work, and will add new insights obtained in experiments carried out by the authors. In the first series of experiments it was shown that the reaction does not occur at an appreciable rate, as is expected from thennodynamic considerations. In the second series of experiments it was shown that zinc does not fume from the slag at a significant rate unless a reductant has been added. This again is in accord with thermodynamic considerations, but is in contradiction to some of the experimental results reported in the literature. A third series of experiments was carried out with excess coke being present, so that the rate of supply of reductant was not in any way controlling the rate. The kinetics of zinc oxide reaction were then found to be independent of the zinc oxide concentration, but increased with increasing basicity, and temperature. The presence of high concentrations of FeO in the slag also improves the kinetics. At low zinc oxide coneentrations iron oxide reduction occurred in parallel with zinc oxide reduction. We propose that (under the conditions of this work) the kinetics were controlled by a chemical step, namely the rate of desorption of an adsorbed CO2 species. This is the same mechanism as reported by Belton and co-workers for the kinetics of the reduction of FeO. This explains why the reduction of metal oxides in slags by hydrogen is often faster than by CO.

Jan 1, 2003

By Ali Hasham

Reduction rates of FeO in CaO-SiO2-Al2O3 slags by Fe-C melts have been investigated experimentally at 1723 K. The rates were estimated using experimentally determined CO(g) evolution rates. Flash X-ray images were employed to visualize the behavior of the melt-slag interface during the reactions. The influence of melt interface was examined by conducting two types of experiments - (i) dropping one (or several) Fe-C droplet(s) weighing 2 g into the molten slag bath, and (ii) dropping a small amount (10-30 g) of slag onto a Fe-C melt weighing 400 g. The rates from both types of experiments were compared and analyzed to determine the rate limiting steps. It was established that neither the carbon transport in the Fe-C melt, nor the transport of gas species in the gas film adjacent to Fe-C melt was responsible in limiting the reaction rate. It is possible that the slag phase mass transport may be controlling the initial reduction rate in the droplet experiments. However, a, different mechanism was responsible in limiting the reduction reaction when the overall %C in the droplets fell to about 2-3.

Jan 1, 1992

By Fiseha Tesfaye, Pekka Taskinen

"Thermodynamics of the equilibrium phase assemblage Ago_9Cul.lS-Cu2-xS-CuS have been studied by an EMF -method. The ternary phase was synthesized from the pure Cu2S and Ag2S in vacuum furnace at high-temperature and mixed with appropriate compositions of Cu2S and CuS to form the cathode electrode. The EMF-measurements were made on the solid-state galvanic cell Pt(-) I Ag I RbAg,ils I Ago9Cu1.1S-Cu2-xS-CuS I Pt(+), in a temperature range from 316 K to 498K.Based on the measured EMF vs. T relations, thermodynamic functions (?fG° , ?fS and ?fH°) of stromeyerite (Ag0.9Cu1.1S) in equilibrium with Cu2-xS and CuS have been determined. The obtained experimental values have been compared with the available literature values. New experimentally determined thermodynamic properties of the solid solution (Ag,Cu)2Sss were determined.IntroductionDue to intense mining of high grade sulfide ore minerals in the past, recently, the available sulfide ores are poor in metals and becoming increasingly complex; such that, the production of high grade metals by the conventional pyrometallurgical processes is compromised. Consequently, smelters are in need to modify their operating flow sheets and strategies for processing more complex feed materials economically, while meeting the strict environmental regulations. To make the appropriate modifications, accurate thermochemical data of phases and phase assemblages which exist in these complex ore minerals are essential.Silver-bearing sulfosalts are encountered in ore minerals for the production of base metals and are common sources of silver. Among the silver-based sulfosalts, stromeyerite (Ag0_9Cu1.1S) is relatively common ore mineral in most hydrothermal vein and replacement deposits [1]. Recently, the ternary chalcogenide compound Ago0.93Cu1,07S has been studied, intensively, due to its high ionic conductivity and gradual disorder in the sequential phase transitions [2]. Therefore, accurate knowledge of the thermodynamic properties of stromeyerite has considerable fundamental and practical interest in many aspects of extractive, chemical and physical metallurgy."

Jan 1, 2014

By G. R. Adhikari

Step 4: Selection of explosives and initiation system Various types of explosives are manufactured in India and a wide choice is available among them that include nitroglycerin based explosives, slurries, emulsions, ANFO (ammonium nitrate mixed with fuel oil) and heavy ANFO. The choice is also available between cartridged and bulk loading systems. In Indian mines, much importance is unduly given to the cost of explosives alone which is not conducive to optimization of blast design parameters. The concept of energy per meter of blasthole and the way in which the total explosive energy is partitioned between shock and heave is not considered in the prevailing practices. Besides, very little efforts are made to objectively evaluate the performance of explosives for a given site condition. Tailoring explosives is limited to changing the density of the bulk explosives. Cartridged explosives are still being extensively used in large operations where bulk explosives should be the preferred choice.

Jan 1, 2002

By Rodney D. Lamond

The need for blast vibration monitoring can be attributed to a combination of three factors: Structural damage, Blast design and Human annoyance. Traditionally, vibration damage criteria are prescribed in terms of peak particle velocity (PPV), as measured or predicted in the ground surrounding a blast. The PPV in the vicinity of a blasthole is strongly influenced by the quantity of the explosive per delay. In general, the existing prediction models give reliable results but fall short of addressing the change in PPV when the charge is decoupled and/or distributed.

Jan 1, 1995

By D. A. Jacobson

Mining operations, whether new or existing, are constantly looking for ways to maximize production and improve energy efficiency, while keeping the footprint required to a minimum. The Nordberg MP1250 cone crusher was designed with these three goals in mind. A series of side-by-side evaluations comparing an MP1250 to an MP1000 were completed at two Freeport-McMoRan operations. The first evaluation began October 2009 in a tertiary position and the second began March 2010 in a secondary position, where it remains in full production today. Utilizing 25% higher power capacity than the existing MP1000 tertiary crushers, the MP1250 had 29% higher capacity and 17% lower specific energy, adjusted for differences in feed and product size. The MP1250 compared to the existing MP1000 secondary crushers achieved 30% higher capacity at a slightly reduced specific energy, while achieving a finer product. The MP1250?s higher capacity and energy efficiency may have application in many crushing plants. Depending on site specific economic factors, greenfield projects may benefit from a smaller footprint and less ancillary equipment, whereas brownfield projects may benefit from higher capacity or a finer product within the same footprint.

Jan 1, 2012

By W. D. Mulholland

"I ASSUME that any effort on my part to deal with the question of the importance of the mining industry is going to be largely an exercise in preaching to the converted, but there are one or two aspects that I'd like to particularly mention.The first is that, in terms of almost all factors, the mining industry is a very important industry in Canada. It is important in terms of employment in relation to the gross national product of Canada and it is particularly important in the international trade of Canada. So far from being insignificant domestically, it is also an extremely important factor in the international picture. That's an important point to bear in mind, because as we talk about all the other matters we never can lose sight of the fact that mining management always has to be conscious of its international competitive position. It is something that one forgets at one's peril, and to a somewhat greater extent than is true of many other industries, those managements have to compete in an international context for their markets, to some extent for their people for specialized skills and of course for finance. In the evolution of domestic policies it is a very, very perilous step to take to impair that competitive ability of the domestic mining industry."

Jan 1, 1972

By Steven E. Mischler

The exposure of mine workers to diesel particulate matter (DPM) and gases is an issue of great concern to the underground mining community in the United States. Approximately 30,000 underground miners are potentially exposed to high concentrations of DPM. In January of 2001, the U.S. Mine Safety and Health Administration (MSHA) promulgated rules setting compliance standards for both underground coal and metal / nonmetal mine workers. As industry works to achieve compliance with these standards, mine operators are looking for feasible methods for reducing DPM concentrations in their mines. In addition, the industry needs methods to accurately measure DPM to ensure that the control strategies they adopt are working successfully. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) conducts research to evaluate control technologies and monitoring instrumentation that can be used to reduce the diesel particulate matter (DPM) exposure of mine workers. An overview of the strategies being utilized in underground US mines to reduce DPM concentrations will be presented. Also, updates on the development of diesel monitoring instruments such as the continuous elemental carbon monitor or the Personal Dust Monitor for DPM measurement will be provided.

Jan 1, 2010

By Jack F. Harang, P. B. Leavenworth

Development during the year 1941 on the Texas Gulf Coast resulted in the dis covery of 27 new fields as compared to 26 fields for the year 1940. Drilling.—During the year, 1405 wells were drilled. Of this number, 1031 were completed as oil wells with 375,000 bbl. daily of new production; 50 were com pleted as gas wells and 324 were failures. The most active area was Jackson County, where 375 wells were drilled and 336 of them accounting for 190,000 bbl. daily of new production. Types of Fields.—Of the 2 7 new fields, 14 are considered to be oil fields, 8 are listed as gas-distillate fields and 5 as gas fields. This may be compared to 26 fields found in 1940, of which 14 were oil fields and 12 gas-distillate fields. Producing Sections.—Frio discoveries retained their predominant position by having 10 Frio fields discovered in comparison to 6 fields in the Wilcox, 4 in the Yegua, 5 in the Miocene and 2 in the Jackson. In the previous year 15 Frio fields were found, 4 in the Wilcox, 2 each in the Yegua, Cook Mountain and Miocene, and I in the Jackson. Production.—Production increased over 1940 approximately 10 per cent, being 113,726,893 bbl. for the year 1941 and 104,127,247 bbl. for 1940. The statistics in Tables I and 2 include distillate and condensate as oil production because no separate reports have been compiled. It is hoped that this separation may be possible some day, but as a great many fields produce both oil and distillate and these arc commingled in pipe lines, separation of statistics will be more difficult than for other areas. New Fields Big Hill, Jefferson County.—Stanolind Oil and Gas Company's No. I George D. Anderson was completed as a gas well from a Frio sand at 8705 to 8720 ft., on Dec. 24, 1941, after having been drilled to a depth of 9500 ft. Additional development is being carried on but it is not possible to evaluate this discovery at this time. Brushy Creek Field, Lavaca County.— Shell Oil Corporation's No. I D. G. McManus was completed as the discovery well in the Brushy Creek field on Oct. 29, 1941, from a Wilcox sand through perforations at 7225 to 7230 ft., making gas and 180 bbl. of 59° gravity distillate. This well was bottomed at 10,998 ft. in the Wilcox. No statement can be made at this time as to the importance of this discovery. Chenango Field, Brazoria County.—J. N. Rayzor et al. completed their No. I Sarah J. Christian through perforations at 8564 to 8572 ft. in a Frio sand, for 453 bbl. of 37.7° gravity oil, on Feb. 6, 1941, after having drilled to 9564 ft. Several wells were drilled in this area during the year but failed to establish important production. This is considered a minor discovery. Clodine Field, Fort Bend County.—Providence Oil Company's No. I Hatfield was the discovery well of the Clodine field, being completed through perforations at 7499 to 7502 ft. for 108 bbl. of 51.2° gravity distillate, on June 19, 1941. The well was bottomed at 8090 ft. Several wells

Jan 1, 1942

By P. B. Leavenworth, Jack F. Harang

Development during the year 1941 on the Texas Gulf Coast resulted in the dis covery of 27 new fields as compared to 26 fields for the year 1940. Drilling.—During the year, 1405 wells were drilled. Of this number, 1031 were completed as oil wells with 375,000 bbl. daily of new production; 50 were com pleted as gas wells and 324 were failures. The most active area was Jackson County, where 375 wells were drilled and 336 of them accounting for 190,000 bbl. daily of new production. Types of Fields.—Of the 2 7 new fields, 14 are considered to be oil fields, 8 are listed as gas-distillate fields and 5 as gas fields. This may be compared to 26 fields found in 1940, of which 14 were oil fields and 12 gas-distillate fields. Producing Sections.—Frio discoveries retained their predominant position by having 10 Frio fields discovered in comparison to 6 fields in the Wilcox, 4 in the Yegua, 5 in the Miocene and 2 in the Jackson. In the previous year 15 Frio fields were found, 4 in the Wilcox, 2 each in the Yegua, Cook Mountain and Miocene, and I in the Jackson. Production.—Production increased over 1940 approximately 10 per cent, being 113,726,893 bbl. for the year 1941 and 104,127,247 bbl. for 1940. The statistics in Tables I and 2 include distillate and condensate as oil production because no separate reports have been compiled. It is hoped that this separation may be possible some day, but as a great many fields produce both oil and distillate and these arc commingled in pipe lines, separation of statistics will be more difficult than for other areas. New Fields Big Hill, Jefferson County.—Stanolind Oil and Gas Company's No. I George D. Anderson was completed as a gas well from a Frio sand at 8705 to 8720 ft., on Dec. 24, 1941, after having been drilled to a depth of 9500 ft. Additional development is being carried on but it is not possible to evaluate this discovery at this time. Brushy Creek Field, Lavaca County.— Shell Oil Corporation's No. I D. G. McManus was completed as the discovery well in the Brushy Creek field on Oct. 29, 1941, from a Wilcox sand through perforations at 7225 to 7230 ft., making gas and 180 bbl. of 59° gravity distillate. This well was bottomed at 10,998 ft. in the Wilcox. No statement can be made at this time as to the importance of this discovery. Chenango Field, Brazoria County.—J. N. Rayzor et al. completed their No. I Sarah J. Christian through perforations at 8564 to 8572 ft. in a Frio sand, for 453 bbl. of 37.7° gravity oil, on Feb. 6, 1941, after having drilled to 9564 ft. Several wells were drilled in this area during the year but failed to establish important production. This is considered a minor discovery. Clodine Field, Fort Bend County.—Providence Oil Company's No. I Hatfield was the discovery well of the Clodine field, being completed through perforations at 7499 to 7502 ft. for 108 bbl. of 51.2° gravity distillate, on June 19, 1941. The well was bottomed at 8090 ft. Several wells

Jan 1, 1942

By K. Hajmrle

The production of nickel coated mica composite powder by hydrogen reduction of a nickel ammine sulphate solution, followed by the production of molded plastic samples containing Ni/Mica is described. Sample preparation by injection or compression molding is outlined and the better results in compression molding are explained by the combination of better particle-to-particle contact, less particle breakage during processing, and more random particle distribution in the plastic. Three volume resistivity measurement techniques are described and compared. Two of them (conductive paint and silver-rubber electrodes) are found reliable and are used throughout the work. The influence of nickel content and particle size of Ni/Mica on volume resistivity is evaluated and the optimum product defined. One of the most important assets of Ni/Mica, its ease of injection molding, is demonstrated by the good electrical properties obtained with little optimization of the injection molding process. Surface roughness of molded plastics with and without Ni/Mica is briefly discussed. Shielding effectiveness of Ni/Mica in four plastics (PP, ABS, PBT and PC) is presented and correlated to volume resistivity data for the same materials. The addition of 15 to 50 weight % Ni/Mica (3 to 16 volume %) to plastics and subsequent injection or compression molding produces composite materials having low volume resistivities (0.03 to 1 ohm.cm) and high shielding effectiveness (40 to 70 dB).

Jan 1, 1988

By D. Anthony, R. A. Williams, R. Raponi

Barrick Gold Corporation in conjunction with SNC Lavalin Engineers and Constructors have developed basic engineering design for counter current decantation thickener (CCD) plants capable of processing 44 000 t/d. To achieve this throughput in a single train, the largest high-rate thickeners installed to date have been utilized in concert with large process slurry and solution transport systems. Process reliability and plant operability and maintainability have been carefully considered in order to develop a practical, yet cost effective design. The design also incorporates the challenges associated with installation of large equipment and structures in a remote location, with a climatically hostile environment, situated in a high seismic activity zone.

Jan 1, 2002

By T. A. Lang

The objective was to develop a Program Plan of analytical studies and tests for determining ( 1) the optimum installation tension of a coal mine roof bolt, (2) the most valid bolt support theory or theories, and ( 3) the most valid roof failure theory or theories. On this basis a comprehensive literature search was made and significant material dealing with coal mine roof behavior, roof bolting and roof support was collected, reviewed, classified and analyzed. Emphasis was given to the influence of rock reinforcement on the control of deformation, stress field modification and mine roof stability. An assessment was made of the effect of various parameters including bolt tension, bolt pattern and time of installation, on the effectiveness of rock reinforcement systems, and equations developed for bolt tension as a function of these parameters, and rock properties. From these studies, a major program plan of tests and studies was developed for verifying and validating the most tenable theories of roof behavior and roof support and for determining optimum bolt installation tension.

Jan 1, 1979

The following letter has been received from Professor P. A. Young, Head of the Department of Mining and Mineral Engineering at The University of Leeds, England. Extractive and process metallurgy The first annual TMS-AIME Extractive and Process Metallurgy Fall Meeting:1983 International Sulfide Smelting Symposium, will be held from 6th to 9th November, 1983, in San Francisco.

Jan 1, 1982