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By B. Yarar

Samples of coal from an adit in the Fording River District of British Columbia showed hydrophilic properties between depths of 0-24.5 meters and was naturally hydrphobic at higher depths. Laboratory experiments indicated that weathered samples (i.e., those mined at 0-24.5m) could be upgraded by froth flotation at pH<2 following slimes removal. The i.e.p. of samples varied regularly between pH=1.6-4.1, the weathered fractions being at the lower end of the pH scale. These values followed a pattern comparable with the flotation behavior of samples. A patchwise structure for coal surfaces determining the resultant disjoining pressure, which in turn determines flotation-non flotation relationships is postulated.

Jan 1, 1982

By Kot F. Unrug

When reading different studies discussing trends in coal mining, it appears that a substantial expansion of output by the year 2000 is predicted, even in the most pessimistic forecasts. Depletion of shallow, easy-to-mine deposits is only a matter of time, and the future average mining depth will increase. The proportion of slope to shaft mines operated during the next decades will change in favor of the shaft mines. Since an increasing amount of shafts in new nine developments seems to be inevitable, it appears appropriate to focus more attention on shaft design criteria. Some valuable papers have recently been published (1) that emphasize geotechnical aspects of shaft design. In the discussion that follows some other aspects of design criteria will be evaluated.

Jan 1, 1984

The Coeur Rochester Mine is one of the largest and lowest cost primary silver mines in the United States. In January, the mine surpassed 3.1 kt (100 million oz) of historic silver production. Rochester is owned and operated by Coeur d’Alene Mines, the world’s largest primary silver producer. Rochester is the world’s seventh largest silver mine. It also produces gold — more than 31.1 t (1 million oz) in historic production. Cash operating costs have averaged 8 cents/g ($2.58/oz) of silver since operations began in 1986.

Jan 1, 2004

By Thomas D. Kaufmann

Introduction Mining has always been sensitive to the fluctuating income of downstream customer industries. The industry is now becoming more vulnerable to booms and busts as economic pulsations increase and demand for mining products shows little or no long-term growth. As the general economy has become more cyclical in the last decade, the capital-intensive primary industries have become more aware that timing as well as preparation of survival plans are vital in investment decisions. Strangely, however, some of us have not yet included the business cycle in our feasibility studies. Cyclic prices and volumes and fluctuations in profits and cash flows do not fit our linear models. The increased cyclical nature of our economy is recent and poorly understood. Forecasting peaks and troughs is still more an art than a science. Nevertheless, avoiding business cycle parameters can lead to error in value estimation and contingency planning of new projects. Metal and Mineral Industries More than half the iron and steel, aluminum, copper, lead, zinc, manganese, tin, nickel, molybdenum, cobalt, and chrome that we mine, smelt, upgrade, and recycle goes to construction, transportation, capital goods, and consumer durable industries. All are cyclical. Their products are consumed slowly, so replacement can be postponed in recessions. Purchases of such goods are usually financed by debt, and their customers are sensitive to highly cyclical changes in interest rates. During prosperous periods, people tend to buy capital goods despite high interest rates. Upstream industries also tend to be whipsawed by inventory cycles. With high interest rates and good transportation, downstream fabricators can lighten their inventories during recessions. They know that upstream suppliers can deliver supplies and raw materials immediately, And, with the advent of electronic accounting, the fabricator with timely inventory information can afford to hold fewer contingency stocks. Likewise, when recovery returns, inventories surge back through industry pipelines, accelerating demands on primary supplies. The price elasticity of most primary products is low. Their share of the value of finished products of the industries they supply is generally small. The 60 kg (130 lb) of aluminum in a car is vital. But whether it costs $80 or $130 will not visibly influence the demand for an automobile. With low elasticities of demand, the primary producer is hit with decreases (or increases) in prices and in sales volume, during recessions as well as recoveries.

Jan 6, 1984

By Louis W. Cope

Since its discovery, Cuba has been called the “Pearl of the Antilles.” The country remains that, albeit a little tarnished these days. In Havana, many of the buildings are being refurbished, while some new ones are under construction. Since 1991, the laws have been relaxed so that Cuba is developing a mixed economy of central control with free market. Joint venture agreements have been signed with businesses from many countries. This does not include the United States due to its embargo. But even these regulations have been relaxed some.

Jan 1, 2003

By P. M. Lin

The problem of surface subsidence over abandoned mine lands is becoming more common due to the development of housing in suburban areas of abandoned mined lands. Subsidence can induce damage to estate properties, engineering structures and the environment. Houses, buildings, roads and utility pipelines may be fractured or broken or may collapse due to subsidence. The ground surface may be depressed and sink gradually or suddenly. The surface and subsurface water flow may be disrupted causing a change in flow pattern or depression of the water table. However, techniques for predicting abandoned mine subsidence are not yet well developed. Presently, one cannot predict when and where mine subsidence will occur. People have to wait until it occurs and then apply a suitable measure to remedy the damages.

Jan 1, 1990

By Sepp A. Kutschera

are gaining increased interest for over­burden removal and ore production at large open cast mines. The application of bucket wheel excavators is still tied to soft un­consolidated rocks and soils, while belt conveyors can cope with all kind of matri­als restricted only by the top grain _ size. Therefore, mode of transport and the re­quirement of down stream ore processing de­fine the materials size distribution. These requirements are usually met by primary crushing or scalping. The paper discusses general applica­ tion criteria of bucket wheel excavator with systems primary for in-pit overburden crusher removal. and It _indeapits scalper units and discusses their technical and operational features. It further com­pares the capital and operating cost struc­ture relative to the syste

Jan 1, 1992

By Michael J. Virnig, Kathryn C. Sole, Murdoch W. MacKenzie, Michael R. Davis

A solvent-extraction process has been developed for the removal of copper cyanide complexes from aqueous copper/gold cyanide solutions formed in gold-recovery circuits that treat ores containing cyanide-soluble copper. The process uses LIX® 7820, one of the LIX® 7800 reagent series developed by Henkel. It is based on a mixture of Aliquat® 336, a quaternary amine, modified with an alkylphenol, 4--nonylphenol. Extraction and stripping data for the base metal cyanides and thiocyanate are presented. Methods for the recove1y of copper and cyanide from the upgraded strip liquor are reviewed. A flowsheet based on this chemistry and a preliminary economic evaluation of a solvent-extraction circuit combined with the cyanide-recovery process developed by Metallgesellschaft Natural Resources (MNR) are also presented.

Jan 1, 1999

By G. S. P. Pereira, E. M. R. Santos

Acid mine drainage (AMD) is a serious environmental problem in mining activities. Prediction is the first step for evaluate the potential of acid generation and there are some possible methods to estimate it. They are described as static tests, which examine the balance between acid producing and acid consuming materials, and kinetic tests, which attempt to predict drainage quality overtime. Static methods are very simple and give a qualitative classification of the ores based on their potential to generate acid drainage. The characterization of ores to determine their acid producing potential is vital for the prevention of long term environmental liabilities. Laboratory tests were conducted under different methodologies to predict the acid producing potential of sulphide overburden, ore materials and tailings from a deposit of copper ore.

Jan 1, 1999

By N. Vayenas

Modern mines possess a wide variety of capital intensive equipment. Equipment failures and the associated down time contribute significantly to the overall maintenance, operating and production costs of a mine. Reliability investigations are becoming a standard practice, as the equipment becomes more complicated and the effective use of resources is critical for achieving higher productivity and mine safety. In view of the recent global initiative for sustainable development in the mineral industries, reliability of capital intensive machinery should be considered as a key indicator for sustainable development and growth. This paper discusses the application of equipment reliability as a sustainability indicator and proposes a methodology for its practical use. Reliability of equipment systems is useful for product life cycle assessment, mine performance measurement and evaluation.

Jan 1, 2007

By J. Chappell

The Nuggety Gully prospect is located 170 km (106 miles) south- east of Port Hedland and 40 km (25 miles) northeast of Marble Bar in the Pilbara Region, Western Australia. The area is held under title by Esso Exploration and Production Australia, Inc. The prospect covers a significant, but currently uneconomic body of molybdenum and copper mineralization of porphyry style, associated with Archean high level acid intrusives intruding sediments and volcanics of a narrow east-west Archean greenstone belt. The Nuggety Gully intrusive rocks have been dated at 3.2 b.y. ± 117 (de Later, oral communication). The current resource estimate for the deposit is 102 Mt (1 12 million st) of 0.1 1 % Mo and 0.15% Cu.

Jan 1, 1991

By Stephen J. Navin, Francis P. D. Navin

Long-distance movement of various materials by conveyor is becoming common; therefore, it is no surprise that conveyors are frequently found in very long tunnels. In such long tunnels, there is a continual controversy between the tunnel operator&apos;s requirement for a maximum of clear space for the conveyor and vehicles and the investor&apos;s wish to make the minimum capital investment for excavation. This analysis shows that the question becomes more pressing as the tunnel becomes longer. The result given in this paper is a straightforward method by which an economic and operational optimal tunnel width may be selected for any specified tunnel length. Detailed computational formulas are developed relating costs of construction, vehicle operation, vehicle accidents, and conveyor downtime to both tunnel width and length.

Jan 1, 1985

By M. K. Pathak, A. K. Mukhopadhyay, D. C. Panigrahi

Changes in machinery operating and design parameters often result in unexpected vibrations or changes in the vibration patterns. Vibration in a system is an undesirable element that can cause machinery distress. Potential damage can be prevented by identifying the vibration level that is due to the changed operational parameters. This is necessary for the safe and reliable operation of plant equipment. This paper presents a documented study on vibration events that resulted from alterations in operating and design parameters in a mine ventilation fan and analyzes the causes by defining the sequence of events that led to its performance deficiency. This paper is based on experimental effort to study the vibration behavior of a ventilation fan under varying operating conditions.

Jan 1, 1999

By A. K. Bakshi

In cold regions, rinsing of spent cyanide from leach heaps is stopped during winter and is resumed again after the snow melts. The effect of this idle time on the overall removal process was studied in this experiment. Samples were collected for rinsing tests from one heap at a gold mine near Fairbanks, Alaska. Continuous and interrupted rinsing of this sample were carried out in test columns. The rinse solution was analyzed at regular intervals to determine the rate of cyanide removal from the solids. It was found that total cyanide concentration per rinse cycle for interrupted rinsing test was higher than for the corresponding continuous rinsing test. As a result, interrupted rinsing required less rinsing cycles than continuous rinsing.

Jan 1, 1995

By G. Wang

Industrial minerals processing has gained importance lately, not only due to its wide range of new and regular applications in processing different industrial minerals, but also due to the strict specs under which products are commercialized. Among the processes applied to industrial minerals, flotation is a leading technology. The laboratory study and commercial operation demonstrate that the sulfonated reagents are very effective collectors for industrial minerals. This paper compares synthetic petroleum sulfonate with fatty acid on iron reduction in glass sand processing and describes the effect of conditioning pH on iron reduction using synthetic petroleum sulfonate as collector, the effect of molecular weight of natural and synthetic petroleum sulfonates on their flotation performance and the enhancement made for certain products.

Jan 1, 2011

By David D. Gallagher

Customer demand for greater efficiency and reduced operational costs on modern overland conveyors has focused attention on the conveyor belt&apos;s rolling resistance properties. Studies have indicated as much as 60% of the power losses on a long horizontal conveyor can be attributed to the indentation of the pulley cover rubber as it passes over idlers. This paper will compare tan delta values of different compounds with large scale rolling resistance test data from the University of Hannover. Results will then be compared to actual power consumption data gathered on several long overland conveyors using identical belt construction except with different pulley cover compounds. Concluding comments will be made indicating substantial operating cost differences based on the rolling resistance of the cover compound.

Jan 1, 2000

By Michel Grenier, David A. Young, Brent Rubeli, Mahe Gangal

This work forms part of a study being conducted into the feasibility of constructing a prototype Load Haul Dump (LHD) vehicle for operation in underground Canadian mines. A series of in-laboratory assessments were performed to determine the relative contributions of a Deutz F4L912W (54 HP- conventional vehicle engine) and a Deutz F2L 2011 (31 HP hybrid vehicle engine) to diesel emissions concentration during mine transient duty cycles and steady-state operating modes respectively. Results indicate significant reductions in the quantity of gaseous and particulate emissions with the application of the hybrid system and a high-efficiency ceramic element filter. This paper describes the engine test protocols and the results of this laboratory study.

Jan 1, 2006

By S. Eugene Sankey, Geoffrey L. Payne

Fundamental choices in flocculant selection often come down to the lower cost of solid grade products versus the convenience of liquids. The ideal product would be a low cost solid grade flocculant which requires minimal handling and no sophisticated dissolving equipment. Recent polymer developments have lead to the commercialization of a limited range of dry polymers that can be screw fed at controlled rates directly to process streams without the need for predissolving. Other developments include dry polymers that can be directly added to mix tanks without the need for sophisticated wetting systems. The latter will make dry flocculants especially attractive for smaller users. Examples of these new products and their application in industrial and municipal waste treatment will be provided.

Jan 1, 1994

By P. Verhoeven, G. Hefter, P. M. May

The dissociation (ionisation) constant of hydrogen cyanide, pKa(HCN), has been measured by high precision glass electrode potentiometric titrations in saline solutions containing up to 5 mol/L sodium chloride. The dissociation constant of water that is necessary for the calculation of pKa(HCN) has also been measured. In saline solution, and in contrast to literature values, pKa(HCN) changes considerably at both high and low ionic strengths as a result of changes in activity coefficients. In addition an equation is presented, using literature data, that describes the variation of pKa(HCN) with temperature up to 150°C. The significance of the changes in pKa(HCN) for optimising the pH of alkaline cyanide gold recovery streams is briefly discussed.

Jan 1, 1991

By E. Yuksel

Noted as one of the 20 major economies of the world, Turkey is a semi-arid plateau between the Eurasian and the African continents. With its surface area of 780 thousand sq km, it supports a population of 70 million people. While the mining history of Turkey can be traced back as far as 7 000 B.C., mining currently generates only 2% of Turkey’s gross national product. Turkey has 77 of the 90 principal minerals that are mined world-wide. Currently, some 5 000 mine occurrences including copper, lead, zinc, iron, gold-silver, chromite, sepiolite, mercury, and coal deposits, soda ash, marble, zeolite, feldspar, magnesite deposits, as well as the world’s largest known borate deposits, have been discovered and partially explored.

Jan 1, 2004