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By Truman Harrington

During the last decade, diesel engine manufacturers focused their research efforts on higher efficiencies and horsepower-to-weight ratios. The result was horsepower increases of between 20% and 30%. At the same time, coolant volume decreased by about the same amount. This has made coolant maintenance more important to ensure a long life for the engine and its cooling system. Due to dilution and additive depletion, supplemental conditioners are usually added to the coolant system during an oil change. Dilution occurs when coolant leaks from the system, and water or non-conditioned antifreeze is added. Depletion is a more complicated process that involves oxidation, neutralization, precipitation and metal surface reactions.

Jan 1, 1991

By Will D

This presentation is to outline the current practice of mechanised stoping a one-metre wide, gold bearing ore body to optimise fragmentation, minimise dilution and reduce stoping costs.Coolgardie underground operations have historically been mined using traditional shrink stope methods, but in this recent economic environment (with falling gold prices and high costs of traditional methods) it was necessary to look for alternative methods in order to reduce costs and increase productivity.Although still in a learning and refinement phase, CGNL is satisfied that it is feasible, practical and more economic to use mechanised long up-hole stope and long-hole rising methods to significantly reduce the mining cost, reduce dilution, increase safety and increase productivity three-fold compared to traditional airleg methods used throughout the Fasten Goldfields.

Jan 1, 1993

By Walter Weeks

THE process of cooling air by allowing it to expand and do work in an engine is well known, but the theory of obtaining cold air by free expansion without the aid of an engine operating with cutoff has been little discussed. CASE I If compressed air is allowed to expand to the atmospheric pressure through an orifice in an air line that is supplied by a running compressor, no cooling results except the negligible one due to the Joule-Thompson effect, which will not be considered in this discussion. The effect of moisture will also be neglected.

Jan 1, 1937

By Walter S. Weeks

THE process of cooling air by allowing it to expand and do work in an engine is well known, but the theory of obtaining cold air by free expansion without the aid of an engine operating with cutoff has been little discussed. Case 1 If compressed air is allowed to expand to the atmospheric pressure through an orifice in an sir line that is supplied by a running compressor, no cooling results except the negligible one due to the Joule-Thompson effect, which will not be considered in this discussion. The effect of moisture will also be neglected. Symbols P1 Absolute pressure in pipe line, lb. per sq. ft. P3 Atmospheric pressure, lb. per sq. ft. V1 Volume occupied by 1 lb. air in pipe. V3 Volume occupied by 1 lb. air at P3. Cv Specific heat of air at constant volume, B.t.u. per lb. per deg. F. Cp Specific heat at constant pressure, B.t.u. per lb. per deg. F. T1 Absolute temperature of air in pipe, deg. F. T3 Absolute temperature of air outside after expansion and mixing and coming to rest. J Mechanical equivalent of heat (778 ft. lb.) R Gas constant for air, ft-lb. per deg. F. = 53.3. Formulas Consider 1 lb. of air moving out of a pipe. The air behind it does work on it to the extent of P1V1 ft-lb. This work is really done by the thrust of the piston of the compressor and does not come from any energy that exists in the air in the pipe. The pound of air contains

Jan 1, 1937

By Martin Chabicovsky, Milan Hnizdil

Emulsions are frequently used for the cooling and lubrication of working rolls during the cold rolling. The fact that the lubrication and cooling are not separable makes the optimization of both functionalities difficult. The higher emulsion temperature decreases the cooling efficiency compared to cold water. Heat transfer and fluid flow laboratory (Czech Republic), CRM (Belgium), Tata steel (Netherlands) and Henkel (Germany) cooperated on the increasing of a cooling efficiency during cold rolling. Part of this research was focused on an influence of the emulsion composition on a cooling intensity. The cooling efficiency was laboratory investigated. The stainless steel sample with thermocouple was heated and then it was cooled by a nozzle. Tests were performed with various emulsions and pure water. The heat transfer coefficient was computed from measured temperatures. The cooling intensity (heat transfer coefficient) of all tested emulsions was similar but an increase of the cooling intensity was found with water. Further various emulsions concentrations were tested. Results showed decreasing cooling intensity with increasing oil concentration. Adding additives therefore is thought to cause a noticeable decrease of the cooling intensity.

Oct 1, 2019

By Yoshio Hiramatsu

In Toyoha mine near Sapporo, the ground temperature is very high, perhaps due to inflow of hot mineral water, the origin of which may be rock masses intruded by the igneous activity in the Tertiary period. The rock masses are found about 2 km east of the mine, their temperature being estimated at from 770 to 870 K at a depth of 3 km. In this mine several veins bearing zinc and lead ores have been mined down to the depth of 300 m from the level of the main entry, of which altitude is 551 m above the sea level. Formerly no attempt was made at development of the deeper part of the mine than the 350 m level from the main entry. Let us indicate hereafter the levels in this mine in such a way that the level 300 m deep from the main entry is denoted as 300 mL. Since 1974, however, the 450 mL of Tajima vein has been developed by deepening No. 5 Shaft to, and by driving drifts in the level. Much hot mineral water has been flowing into the drifts from rock. After twenty-eight months from the beginning of development, the total length of excavation amounted to about 1300 m. The success in development so far may be attributed to cooling rock and air with chilled water and to adopting heat-resisting explosives and detonators. This cooling costed very much and for further development in this level a more effective and economical cooling is desired if possible. To obtain fundamental data for designing an economical cooling, the authors investigated, as a preliminary study, the heat balance in the main drift of 450 mL, by measuring the temperatures of air, rock, hot mineral water, the rates of flow of air and water and so on, in August 1976. They are now carrying out continual measurements of the variations in rock temperature, air temperature and humidity with time. The present paper describes the details of the preliminary study.

Jan 1, 1980

By E. Mokgwamme, T. Goff, M. Mvalelwa, P. Spratt, P. Bezuidenhout, P. Nkosi, H. Joubert, G. de Villiers

Sibanye-Stillwater recently completed a partial sidewall rebuild on Furnace 1 at its Marikana smelter complex. The project involved matte taphole maintenance, which required the removal and subsequent replacement of 18 composite copper-graphite coolers and a section of the lower refractory sidewall. These composite copper-graphite coolers are a newly developed cooling design by Tenova Pyromet, and this rebuild project provided valuable insight into the performance of the composite coolers. The novel composite cooler design was implemented to serve as a safeguard against localised wear and corrosion in the furnace sidewall, particularly at the slag-concentrate interface, where chloride-accelerated sulphidation has been identified as a dominant degradation mechanism affecting the copper cooling elements. The composite cooler design is unique in that all the exposed sides of the water-cooled copper elements are fully encapsulated in graphite, which protects the copper from corrosive sulphur- and chlorinebearing gases and condensates. This sidewall cooling system was designed to improve corrosion resistance, stabilise freeze lining formation, and extend the campaign life of the furnace sidewall. The partial sidewall rebuild was executed during a planned maintenance shutdown with the main objective of replacing the matte taphole lintel bricks. This paper serves as a case study that compares and evaluates the operational performance of the composite coolers before and after the rebuild. The installation method is discussed to highlight the approach taken to ensure a sound installation while minimising downtime, as well as to present some lessons learned in the process.

Mar 6, 2026

By E. P. Palmatier

RECENTLY a cooling system has been in process of installation on the 3400 and 3600-ft. levels of the Magma copper mine at Superior, Ariz. The general system of ventilation employed at this inclined-vein mine is as follows: Ventilating air enters the shafts on the western side of the mine. Booster fans at each level each deliver approximately 38,000 cu. ft. per 'min. to the drifts. This air passes diagonally upward to the upper levels of the mine on the eastern side, where it passes up the shafts to large exhaust fans on the surface. Owing to the dip of the vein, all operations on the eastern side of the mine are above the 2500-ft. level, and those on the western side below the 2500-ft. level. At present, 2500 lineal feet of new drifts are being driven-on each of the 3400 and 3600 levels. The rock temperature is about 135°F. Until the new installation is completed, ventilating air for the two levels is supplied through Flexoid tubing from small booster fans -on the 3200-ft. level. The air picked up by these booster fans has a dry-bulb temperature of approximately 85°F. and a wet-bulb temperature of 82°F. By the time this air reaches the end of the Flexoid tubing at the 3600-ft. level, the dry-bulb rises to 101°F. and the wet-bulb to 86°F. The conditions at the head of the new drift were 102' dry-bulb and 93' wet-bulb.

Jan 1, 1937

By F C. D Michelin

As mines get deeper, the critical underground temperature limits will be exceeded, and an increasing number of mines will need to implement, expand or modify cooling systems. Surface cooling plants have many advantages over underground cooling such as efficient heat rejection, and lower relative capital cost; however the delivery of cooling through long underground distances can result in lost refrigeration capacity before the chilled air reaches the areas it is needed most. Refrigeration plants are therefore often overdesigned in size and capacity to compensate for underground losses.More mines are now utilising real-time monitoring and automated control of ventilation airflow and fan systems to ensure the conditions underground are safe and productive, and power consumption is efficiently managed. There may be significant opportunities to extend ventilation monitoring and control into the refrigeration delivery and control system.Energy reduction is an effective way to reduce costs and CO2 emissions, which is an increasingly important part of corporate governance. More efficient refrigeration control is a further step toward reducing energy consumption. This paper looks at an added step in how real-time monitoring can assist in controlling the output and chilled air delivery of a cooling plant. The requirements, implementation, benefits and challenges will be discussed.

Oct 12, 2022

By B Belle, M Biffi

Cooling of coal mines in the Bowen Basin, characterised by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures of over 50¦C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures (WBT) to below 27¦C at which point the risks of heat stroke or other heat-related issues are manageable. The capacities of these systems are in the range of 6 MWR to 10 MWR. The relationship between high working temperature environments and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long-term cooling pathways to effectively manage thermal hazards. Thermodynamic modelling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarises the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers (BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants, are discussed in this paper. Finally, the comparison of ærentalÆ versus æownershipÆ of cooling plants is analysed as part of long-term cooling strategies.CITATION:Belle, B and Biffi, M, 2013. Cooling pathways for deep Australian longwall coal mines of the future, in Proceedings The Australian Mine Ventilation Conference , pp 223-236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

Anglo Platinum is in the process of introducing a number of initiatives, varied in nature, on a scale that will impact operations in the short, medium and long-term. The advent of mechanization on a large scale and the introduction of new mining technologies therefore require a different approach to the design of ventilation and cooling systems. In addition, the ventilation and cooling systems serving increasingly deeper operations will place a greater demand on electrical power consumption?this in an environment where power generation is limited and increasingly expensive. Ventilation and cooling systems currently being employed in platinum operations have evolved from practices first pioneered in deep level gold mines. However, in modern and future platinum mines, deepening of operations will take place in a somewhat different environment?particularly in terms of geothermal settings and electrical power utilization. This provides the opportunities to devise novel and energy-efficient ventilation and cooling strategies tailor-made to meet these challenges. The need for refrigeration and cooling at depth will increase the capital and operational cost component of ventilation systems and the medium-term limitations on the availability of electrical power will require the provision of innovative systems. The increased use of diesel-powered vehicles underground, the viability of energy recovery and feasibility of thermal storage opportunities are discussed in this paper. Some of the challenges and the solutions currently proposed in terms of ventilation system design, refrigeration plant selection and chilled water distribution methodologies are described. Changes in strategies core to this discipline that affect the health and safety of employees and the profitability of modern operations are deemed necessary to support the transformations that are envisaged.

Jan 1, 2008

By Austin Whillier, Duncan Mitchell

The problem of heat stress underground in the gold mines is approached on the basis of the heat transfer between the human body and the underground environment. Experimental measurements of radiant and convective heat transfer and a theoretical calculation of maximum evaporative heat transfer enable the maximum cooling power of an environment to be calculated in terms of the dry-bulb and wet-bulb temperature, the mean radiant temperature, the wind speed and the barometric pressure. For most underground applications the cooling power can be expressed as a function of wet-bulb temperature and wind speed only. The relative importance of wind speed and wet-bulb temperature can be assessed: in working places where wind speed is low additional cooling of workmen can be achieved better by increased wind speed than by decreased wet-bulb temperature. The wet kata reading proves to be of limited value as an index of heat stress because environments with equal wet kata do not necessarily have the same cooling power. Finally, thermal equilibrium with the environment is possible when cooling power equals or exceeds the rate of metabolic heat generation. The rates of metabolic heat generation for various underground tasks are indicated.

By N. B. Pilling

THE development of a proper treatment for shells in connection with war contracts has brought to our attention the fact that the temperature of the liquid bath in which steel is quenched has a decided influence on the speed of cooling in the case of some liquids and very little in the case of others. Widely different physical results have been obtained by the use of water spray, water immersion, and oil immersion and further experiment has shown that the quenching effect of water used as a spray or an immersion varies greatly with the temperature of the water. The present experiments were undertaken with the idea of obtaining information of a quantitative nature regarding the quenching properties of a number of liquids used commercially in hardening steel. The general features of such cooling media are common knowledge and in the literature may be found records of numerous attempts to evaluate the cooling power of a liquid when used as a quenching bath. Much, if not most, of the data given on this subject is in the form of a simple statement of the time required for a certain heated mass to cool between two arbitrary temperatures when immersed in the liquid, quite regardless of the path of the temperature change. Our own purpose has been somewhat different. We have attempted to isolate that property of these. liquids having to do with their ability to absorb heat rapidly, as distinct from the behavior of a considerable mass when exposed to different thermal environments. More specifically, from the data obtained through autographically recorded cooling curves of a small standard mass quenched under various conditions, we have tried to analyze the mechanism of heat absorption by the several liquids, measure the changes in its rate as a function of the temperature of the surface of transference, and ascertain the influence of the temperature of -the liquid itself upon both.

Jan 9, 1919

H. M. HOWE, Bedford Hills, N. Y.-One wonders, whether it might not be well to check, by a rather simple and direct way, the inferences that would be drawn from this investigation. Suppose we quench, in these various liquids cylinders of steel, selecting material that is not likely to split in hardening, and then examine their cross-sections micro-scopically. If the cylinder is of any size, you will find a series of concentric bands, a very hard band, a softer band, and a hard band-but it seems that here would be a way of checking the inferences from the cooling curves by comparing these waves of hardness obtained in similar speci-mens quenched in different liquids. One would think that there would be great promise in that way. One's first thought is to quench similar pieces of steel, similarly heated, in different liquids and determine their hardness. I suppose many of us have tried that. We then meet the-difficulty that it is not the most rapid cooling that gives the greatest hardness. There is an intermediate rate of cooling that gives maximum hardness so that you can not by any simple method as that check this cooling method. But it seems possible

Jan 12, 1919

The subject of heat sources in deep hard rock mines, the limitation of forced ventilation to cope with these heat loads and the sizing of refrigeration plants to boost the cooling effect of the ventilation air are discussed. The development of plant selection criteria and operating experience at North Broken Hill Limited is outlined. Future options for North Broken Hill Limited and like deep mines are summarised.

Jan 1, 1982

By Edward Jacobsen, Patrick J. Lydon

"The ongoing expansion of the Oak Creek Power Plant in Oak Creek, Wisc., includes a tunnel bored in rock that connects to four vertical intake shafts approximately 1.5 miles (2.4 km) offshore in Lake Michigan. In 2004, Case Foundation Company was awarded a lump sum contract to install these intake shafts. In spite of delays that shortened the May to September construction season by up to 50%, four shafts and liner assemblies were drilled in 2005 and 2006. The shafts were connected to the tunnel in 2007 by mining upward to reach the lower portion of each liner and then removing its internal bulkheads so that lake water fl owed into the tunnel. The project is one of the largest private construction projects ever undertaken in Wisconsin. The expansion adds 1,230 megawatts of generation. In addition to the tunnel and offshore work, there will be 16 miles (26 km) of railroad track and 6 million cubic yards (4,600,000 m3) of earth work. The 27 ft (8.2 m) diameter tunnel, drilled some 150 ft (46 m) below the surface of Lake Michigan, originates onshore at a pump house. A structural slurry wall was constructed as the foundation for the pump house. The tunnel passes to the south near the current water intake before bearing east toward the new offshore intake shafts, which are 12 ft (3.6 m) diameter by 108 ft (33 m) long steel liner assemblies. These were grouted in place from approximately 3 ft (1 m) above the crown of the intake tunnel and then to 20 ft (6 m) below the lake bottom.Site GeologyOffshore. The plant site is north of the Racine-Milwaukee county line in an area affected by glacial activity. The soil conditions encountered at each shaft location were consistent, with noticeable variations occurring in the top of rock elevations that sloped downward from the innermost to the outermost shaft."

Jan 1, 2008

By R. C. Head

The investigation describe the history of copper in the seventties, as well as indicates the forecast the probable trend of the Copper Industry over the coming decade, and second, to stimulate some discussion on what is a somewhat controversial subject. At the same point, the period of surplus production from about 1972 to 1976-1977, during part of which some voluntary restriction on output maybe necessary. In consecuence, its a necessity for forward planning so that, by 1973-1974, new mines maybe developing to preserve the continuity of supply .

Nov 20, 1969

By John Petty, John Loviza

Single sentence describing content-- "The best ally an Explosives Engineer can have in a court of law is a regulations enforcer stating all codes and standards were met on a jobsite".

Jan 1, 1996

By John Petty, John Loviza

As a blaster, have you ever had that uneasy feeing in the pit of your stomach as a codes enforcement official drives onto your jobsite? Have you ever needed an ally in a court of law against an unjust damage claim? Have you ever wished for a better and more open relationship with the guys who wear the badges?

Jan 1, 1996

By O. E. Kiessling

A GROWING uneasiness in the oil fields indicates that doubts are arising as to the efficiency of the present technical, economic and legal arrangements affecting production. Recent documents of the federal government, debates in state legislatures, editorials in the daily press and statements of oil company executives re-echo the notion that the present methods of producing oil satisfy neither the business man nor the public. Such intimations are of utmost importance, since oil is a vital clement in modern industry and dependence upon it increases as new uses develop. SECTION I-PRESENT SCHEME OF COMPETITIVE EXPLOITATION IS WASTEFUL The oil industry has convinced itself, for very good reasons, that the present scheme of competitive exploitation results in losses, both in terms of quantities of oil and in terms of profits. The story of these losses is familiar enough, and it is necessary only to distinguish and summarize briefly certain factors that are of importance to the following argument. Oil pools are exploited under a competitive economic system based on private ownership and contract; the hope of profits attracts capital and enterprise, and competition is supposed to serve as a regulative factor. Whether such a scheme of industrial organization works is partially dependent on the ability of the producer to withhold or produce is commodity as he sees fit, in accordance with the dictates of market demand.

Jan 1, 1927