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By Karel SPIRKO

The one-dimensional mathematical model of unsteady-state heat conduction through semi-infinite homogeneous and isotropic airway walls with convective heat and moisture transfer between their wet or dry naked surfaces and mine air with time variable temperature and humidity has been developed on the basis of introduction of acceptable simplifications of description of heat and moisture transfer between rock mass and mine air. The analytical solutions for computation of the temperature distribution and surface temperature of the airway walls and floor and for calculation of water vapour pressure near the wet surfaces at given time are obtained by means of the model presented. The presented solutions are derived for general conditions and they could be easily adapted to the actual ones. Results of the model represent basis for balancing heat and moisture transfer between mine air and its surrounding in deep mines under time variable temperature and humidity of the air and enable us to solve complicated dynamic changes of mine air temperature and humidity in an airway system by relatively simple mathematical tools. INTRODUCTION The importance of unfavourable influences and the costs of condition arrangements increases with mine depth. Precision demands on the methods which predict the environmental condition changes and by which it is possible to optimize condition arragements are still increasing. Environmental conditions in deep mines are determined especially by flow velocity, barometric pressure, temperature, and humidity of mine air. Therefore new and more exact mathematical models of mine air flow through airway system and those of heat and moisture transfer between mine air and individual important sources of heat and moisture are developed. The paper presented deals with description and solution of problems of heat and moisture transfer between mine air and airway walls as the rock mass is one of the important heat and moisture sources in deep mines. There are several different approaches to the problem. In some models the moisture transfer between mine air and airway walls is not considered at all. In other models the moisture transfer is described only by certain empirical coefficients. Simultaneous heat and moisture transfer is described seldom. This paper tries to describe in a simple way simultaneous convective heat- and mass-transfer processes taking place on wet naked surface of airway walls by means of corresponding

Jan 1, 1993

By D. Farnell

Large semi-autogenous (SAG) or autogenous grinding mills have become the work-horse of the modern high volume concentrator. They typify the economy of scale - fewer, larger machines doing more work, more economically. With fewer machines, equipment reliability becomes of paramount importance. Realizing this, companies installing new or modernizing existing facilities have placed extraordinary emphasis on purchasing a reliable mill. This, in turn, has had a significant impact on mill design. Kennecott And Codelco - Two Different Approaches Last year, two of the world's largest copper producers, Codelco and Kennecott, undertook the modernization of their main grinding facilities at Chuquicamata and the Utah Copper Division (UCD) respectively. Both selected semi-autogenous milling and both, recognized the importance of the reliability of the primary mills. Each, however, decided on a different approach to optimizing reliability. Codelco placed the emphasis on technical innovation in design and opted for a gearless driven mill. Kennecott chose the more conservative approach of active participation and exceptional quality assurance in mill design and manufacture.

Jan 1, 1987

By Charles Schmidt

Phalabonva (Figure 1) is situated in the northern province of South Africa adjacent to Kruger National Park, about 500 km from Johannesburg. The nearest South African port to Phalaborwa is Richards Bay about 700 km distant by rail.

Jan 1, 1999

By Chester R. Harris

With the passage of the Occupational Safety and Health Act (OSHA) on December 29, 1970 and the formation and growth of the OSHA Agency it spawned, public consciousness of occupational safety was raised. It became accepted that employees had the right to "a safe and healthful workplace". With the possibility of OSHA inspections, employ ers (particularly those with large workforces) began to give serious con sideration to engineering controls, safety programs, and training in a more uniform manner than previously.

Jan 1, 1991

By R. V. Ramani, J. Qin

During the mining process, the in-situ material is broken into different size ranges, from very large pieces to very fine particles. Some of the fine particles become airborne. In underground coal mining, airborne respirable dust is associated with health and safety of the miners. The amount and size distributions of airborne dust are important parameters to effective dust control measures. The design of underground mine experiments, including sampling procedures and sample analyses methods to determine these parameters are presented in this paper. A total of fifteen continuous miner cuts were sampled. The amount of dust generated during the cutting process and the relationship between total and respirable airborne dust concentrations and amounts are examined. The amount of respirable dust airborne is on the average only 0.016% of the respirable dust generated. On the average, 61% of the total airborne dust measured is in the respirable size range. The amount of respirable airborne is on the average 36% of the respirable size fraction in the total airborne dust. For equal proportion of rock and coal material cut, rock contributes about twice as much fines (=0.22 mm) as coal. Additional fundamental research is necessary to further the understanding of the airborne propensity of respirable dusts in mine atmospheres.

Jan 1, 1989

By Sergio Godoy P.

The Los Bronces porphyry copper deposit is located in the high Andes of Central Chile. Ore is mined from several tourmaline breccias and from an earlier porphyry. After years of experience in the geostatistical estimation of reserves in different zones of the ore body, we believe that success lies in considering the evaluation as an integrated process beginning with the analyses of the drilling density and sampling methodology, ending with the critically important reconciliation between the estimated and the actually extracted ore, in general, when errors or differences occur, focus is centered in the calculation stages of geostatistics. However, this paper demonstrates that all the evaluation stages are equally important and require the direct and continuous geologic input to ensure the best possible estimate within the frame of the geologic constraints.

Jan 1, 1992

By H. L. Ehrlich

Processes involving biological solubilization of metal values from ores, or removal of mineral constituents that interfere with metal value recovery from ores by abiological means, published mostly in the last 10 years, are reviewed. Many of them, though promising, have yet to be tested on a pilot scale or applied industrially.

Jan 1, 1987

By Arthur W. Darby

Heathrow Airport is owned and operated by BAA who are engaged in a major programme of expansion. In order to link the expansion of the airport in the west with the existing central terminal area, a twin bore, 8.8m outside diameter, road tunnel,1280m long, is being constructed. The tunnel drives pass over, with limited clearances, an operating railway tunnel, and pass under, with about one diameter cover, the airport taxiways and aircraft stands. Selection of the machine was heavily influenced by the need to minimise settlement.

Jan 1, 2003

By Ahmed I. A. Salama

The problem of estimating separation characteristics by utilizing mass distributions of feed and products is considered. The separation characteristics include mass yield and partition curve. The cases of mass balance and partition functions balance are identified. The developed techniques can handle the cases of two- and three-product separation. Actual data are utilized to demonstrate the proposed techniques.

Jan 1, 1992

By Darrell E. Young

This presentation will define what talc is, how it is mined and processed, and how talc is used in the paper industry. It will also give you some idea about who Luzenac America is and from where it came. Luzenac America was formed in July, 1992 as a result of the acquisition of the talc assets of Cyprus Minerals by RTZ of the United Kingdom. Cyprus Industrial Minerals was then merged with the other RTZ talc interests under the Luzenac name. Luzenac is a town in the Pyrenees of Southern France -and the home of Talc de Luzenac, RTZ's first talc acquisition. The Luzenac Group is the largest talc producer in the world.

Jan 1, 1993

By Edmond O’Donovan

Selection of conveyor drives is an area of great confusion that frequently leads to poor system performance or overcapitalization. Many papers have dealt with the performance characteristics of different drive types, but users have often found that this only leads to further confusion. This paper presents the drive requirements from the "conveyor's" point of view. The drive requirements of different classes of conveyors are examined to illustrate why some drive types work well in certain situations but poorly in others. The appropriateness and shortcomings of different drives are examined in this context, along with the recurrent issue of load sharing.

Jan 1, 2000

By R. J. Wesely, A. D. Zunkel, Tracy B. Braun, Philip L. LeHoux

An overview of gold processing operations at Barneys Canyon Mine is presented with particular emphasis on ore agglomerating experience, leaching and metallurgical accounting practices, and carbon column plant operating approach. The mine, located thirty kilometers from downtown Salt Lake City, is just eight kilometers north of the Bingham Canyon copper mine. Mining was initiated in February 1989 and the first gold was poured in September 1989. Through year-end 1992, approximately 7 million tonnes of ore have been processed and 12,000 kg of gold have been produced. Gold recovery is in excess of 85 percent.

Jan 1, 1993

By Patrick R. Taylor

This paper presents a fundamental study of the thermodynamic and kinetic effects of copper and iron on gold-cyanide leaching. It quantifies the solubilities of the impurities, complex formation, and kinetic effects. The necessity of solution recycle, to meet environmental standards, requires that fundamental information be generated to characterize behavior and allow the identification of treatment methods. Mathematical descriptions of both solubilities and kinetics will be presented

Jan 1, 1983

By Janice M. Zinck, W. F. Griffith

Four different high density sludge-type processes, Cominco HDS, Geco HDS, Tetra HDS Process and the Staged- neutralization process were studied for their effectiveness in treating a low strength Zn-Fe rich acidic drainage solution. Each proms was run continuously for at least two weeks after obtaining steady state conditions. The final effluent quality, lime consumption, sludge density, settleability, filterability, viscosity, neutralization potential, metal leachability, operating and capital costs were measured and evaluated for each process.

Jan 1, 2000

By Leo J. Laughlin

In recent years, heavy mining applications have put an increasing demand on conveyor pulleys. This has resulted in the increased usage of turbine pulleys. The designs of these pulleys are often based upon the failures seen in the conventional welded designs, overlooking the interaction of pulley-shaft system components as the profile of the disc is modified. This paper will focus on the development of balanced design philosophy using case studies of turbine pulleys in heavy mining applications, evaluated with FEA.

Jan 1, 2002

By R. Jedrzejczak

Endako Mine is an open pit molybdenum mine located in the north central region of British Columbia, Canada, approximately 160 km. west of Prince George. Production for the latter part of 1992 is expected to average at 63,500 tonnes per day of which 27,000 tpd constitute the mill feed. This production is achieved with five 15 to 19 cu. yd. electric shovels, six Euclid R190 and two Unit Rig M120 diesel-electric haul trucks, and three 121;.1 inch electric rotary drills. There are three ore zones delineated into pit areas called the Endako, Denak East and Denak West. Present mill feed source is the South East stage of the Endako Pit while the stripping is carried out in the South Wall stage also of the Endako Pit. The mine high grade aggregate is reduced in the primary and secondary crushing circuits before processing in conventional RM/BM/flotation circuits. The majority of the Molybdenum Sulphide (MoS2) is roasted on site to produce technical grade Molybdenum Oxide (MoO3) while a portion is further refined and treated to yield a 99.9% pure Molybdenum Sulphide (MoS2) "Ultrapure" product.

Jan 1, 1993

By William E. Hole

The sand and gravel industry provides an enormous quantity of materials vital to the maintenance of low-cost construction. There has been little effort to conserve this valuable natural resource. In fact, existing regulations which affect sand and gravel operations act more to waste these materials than to conserve them. Another factor affecting the industry is new legislation requiring the reclamation of worked-out pits. Although such legislation creates many administrative headaches for a sand and gravel operator, there exists the possibility through such legislation of gaining some conservation measures that could be helpful to the industry.

Jan 1, 1974

By R. Conor, O&apos

Wastewater treatment systems, both industrial and municipal, produce large quantities of sludge which require disposal. Sludge disposal poses significant environmental liabilities, logistical problems, and economic burdens. Minergy Corporation has developed and implemented several new technologies for the recycling of such high volume wastes as sludge, ash, and foundry sand. These technologies perform mineral recovery from the waste material, converting them into construction material and industrial feed stocks which are inert, marketable products. With a continuously operating processing system installed at the waste source, these technologies reduce handling, eliminate downstream liabilities, and reduce disposal costs.

Jan 1, 1999

By R. H. Seraphim

The name is derived from an Egyptian myth, "A beautiful lone bird which lived in the Arabian desert for 500 or 600 years and then consumed itself in fire, rising renewed from the ashes to start another long life." HISTORY This account of the first history is gleaned from old reports and documents which are listed in the Bibliography and from discussions with old-timers of the district. Prospectors were active in the vicinity of Greenwood in 189 1, and in that year staked the Mother Lode, Crown Silver, and Sunset. Henry White staked the Knob Hill claim in Phoenix on Jul. 15, 1891, and by the end of the year, other prospectors had staked most of the claims covering the valuable ore bodies in the camp. Much surface work done in the early years indicated that the values in copper, gold, and silver were low. Large capital investments were required to develop the ore bodies and build smelters. The discovery that the ore was practically self-fluxing greatly enhanced the value of the deposits. A map of the area showing the geology is given in Fig. 1. The bedded Brooklyn conglomerate is shown in Fig. 2.

Jan 1, 1991

By A. Marabini, J. Cases, M. Barbaro

Outlined is a review of the application of new selective chelating reagents as flotation collectors; calculation methods for the selection of chelating structures, limitation of the function of commercial chelating agents as collectors, and the synthesis of two new classes of chelating collectors with mixed aliphatic-aromatic structure for oxidized lead-zinc ores. Given are: examples of substituted mercaptobenzothiazole and aminothiophenol structures, flotation and adsorption study of an alcoxyl-mercaptobenzothiazole on cerussite, comparison of adsorption of conventional and chelating collectors, study of the influence of the aliphatic structure1 component on the collecting power of chelating type reagent and the design of chelating collectors with optimal structure.

Jan 1, 1989