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This paper presents a review of heat illness in mining, including reference to several recent investigations by the author. Heat illness is a collective term, covering the conditions of heat stroke, heat exhaustion, heat cramps and miliaria rubra. Heat stroke is life-threatening and is by far the most serious condition. It is rare in mining, if appropriate control measures are instituted. Heat exhaustion is primarily due to hypohydration, following prolonged sweating in hot conditions. Symptoms include fatigue, headaches, dizziness, anorexia, nausea, vomiting, shortness of breath, or brief syncope. Confusion, ataxia, prolonged unconsciousness or convulsions are strongly suggestive of heat stroke. Heat cramps are painful involuntary contractions of skeletal muscle associated with work in hot conditions. The limbs are usually involved and the spasms typically last a few minutes, during which the affected part of the body is incapacitated. Heat cramps tend to occur in heat exhaustion, when hypohydration becomes marked. Miliaria rubra is a skin rash caused by extravasation of sweat into the skin, as a result of obstruction of the sweat glands. It occurs after prolonged and profuse sweating in hot environments. It can take three to four weeks of sedentary duties, in an air-conditioned surface environment, for the condition to resolve. Heat illness would be unlikely in underground mining, if the thermal environment was sufficiently well controlled by ventilation and refrigeration. This is however, often not practicable. Where engineering controls alone cannot provide sufficient control of risk, the residual risk can be assessed using an appropriate heat stress index. While procedural controls may further reduce the residual risk, it is important to remember that these are less reliable than engineering controls and cases of heat illness may still occur. Procedural controls include the application of heat stress limits, education, hydration, self-pacing, early symptom reporting, medical advice, acclimatisation procedures, air conditioned accommodation, support to achieve a healthy body mass index, and an effective emergency response capacity.

Jan 1, 2005

By T. J. DeMull

More than 1.81 mt (2 million tons) of low grade ore have been heap leached at the Alligator Ridge mine. Since inception of leaching in 1980, several modifications have been made to ore agglomeration, heap construction, and leach operation practice. These modifications have improved the percolation rate of the ore and the rate of gold extraction from the ore. Changes made in each of these areas are described and the effects of the changes are discussed.

Jan 1, 1984

By M Olsen, L van den Berg

Bowen Basin coalmines suffer from hot and humid ambient conditions during the summer period. The ambient conditions combined with high VRTs, increasing depth of working and significant equipment heat loads results in heat issues underground. Coalmines operate under heat stress management plans as required by legislation with associated trigger action response plans (TARPs). Some mines also employ refrigeration as part of their heat management strategy.A recent case study was conducted on a mine producing about 4.5 Mt/a from their longwall and experiences summer surface ambient temperatures of about 23.5ºCwb. The expected virgin rock temperature is 46ºC at 300 m depth. The mine currently introduces a modest amount of surface cooling at the portal using ‘off-the-shelf’ air conditioning units. This system does not effectively manage face temperature primarily due to positional inefficiency.Underground conditions remain hot in summer and work is typically undertaken in accordance with the Heat TARP. This has a direct impact on the productivity of crews, worker comfort and also negatively impacts the workforce morale. The mine commissioned a study to determine a refrigeration strategy aimed at maintaining underground conditions below TARP levels 90 per cent of the time.The ventilation network model was calibrated against actual temperature data to simulate the heat loads including longwall, conveyor system, strata and auxiliary diesel fleet. This model was then used to determine the cooling requirements for bulk surface cooling, bulk underground cooling, surface district cooling and underground district cooling strategies.These estimates were used to undertake a total owning cost trade-off for the different strategies. The study concluded that a chilled air shaft has the lowest technical risk but the highest total owning cost due to shaft development needs. Introducing chilled water to an underground cooler via boreholes offered the lowest total owning cost and was therefore recommended.CITATION:van den Berg, L and Olsen, M, 2017. Heat load assessment and mine cooling strategies for a longwall coalmine, in Proceedings Australian Mine Vent Conference 2017, pp 231–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Chonghun Han, Tae-Hwa Choi, Young-Hwan Chu

"A statistical optimization method is proposed to maintain stable operation in a blast furnace with stave coolers. The objective of this study is to find the operating condition which maximizes productivity as well as minimizes the heat load on the stave coolers. In this method, we first analyzed historical data and calculated the heat flux of stave coolers and the burden distribution by mathematical models. In this approach, we determined the variables to optimize and manipulated variables to adjust these response variables. Next, we collected the necessary data for the data variables after preprocessing such as removal of noise and outlier. Finally, we constructed empirical models describing the patterns of response variables in terms of manipulated variables by partial least squares regression method, and then these models were used as objective functions for entire optimization problem. By using appropriate optimization algorithm, we determined the compromised optimum operating condition considering all response variables from the past operating conditions.IntroductionBlast furnace operation which is accompanied by complex physical and chemical phenomena is an essential process for steel industry. In this process, iron ore which is charged into the blast furnace from the top goes downward. It is reduced to iron by CO gas and is melted by the heat of combustion of coke and pulverized coal. The pig iron is tapped at the bottom in liquid phase after removing the slag, which floats on the pig iron.The cooling equipment of the blast furnace wall is changed from the plate type to the stave cooler recently. In order to cool the shell uniformly and eliminate shell spray cooling, Pohang No.2 blast furnace of POSCO (Pohang Iron & Steel Company) was equipped with 11 rows of stave coolers. These staves are only 350mm-thick including the 170 mm-deep refractory on the hot face."

Jan 1, 2001

By R Moreby, J Kok, L van den Berg

The high production rates achieved from mass mining methods such as block caving, sublevel caving and longwall mining require large conveyor belts, trucking loops (diesel/electrical) and rail systems for ore handling. However, the ore handling systems used in mass mines introduce a significant amount of heat into the overall ventilation system, which may be problematic at depth or in mines located in hot climates.In particular, the heat load from a conveyor system is not always well understood and consists of various components, including frictional heat from idlers, heat from electrical motors, heat from the drive train and heat from broken rock transported on the conveyor system. This paper presents results from a study that investigated the heat introduced to the ventilation air from a large conveyor system. The conveyor system transports ore with a maximum virgin rock temperature of 41°C from a depth of over 1 km. Air, belt and rock temperatures were measured in the conveyor system to evaluate the distribution of heat loads.CITATION:van den Berg, L, Moreby, R and Kok, J, 2015. Heat load estimation from conveyor systems in mass mines, in Proceedings The Australian Mine Ventilation Conference, pp 63–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By Jane Li, Kevin Tom

"Research has shown that broken rock on conveyor transport systems can contribute upwards of 50% towards the overall heat load in underground mines. However, few studies have made significant efforts to predict the temperature distribution of the ore and air simultaneously, which can help implement heat management strategies. The present investigation explores a transient, analytical heat transfer model to track ore-pile temperature distributions, along conveyor systems in an example underground mine. Production rate, ambient conditions, ore pile thickness and belt velocity are adjusted to evaluate the effect on dry and wet bulb temperatures.INTRODUCTIONWith an ever increasing demand on Earth’s resources due to a multitude of factors like population growth and step changes in technology, pressure on the mining industry to bring out more ore with improved margins is a persistent challenge. Typically, high-volume producing mining methods (i.e., exceeding 5000 tons per day (tpd)) such as sublevel and block caving, room and pillar, and longwall shall utilize belt conveyors instead of trucks as the primary haulage method to surface to save on operational costs (de la Vergne, 2014). However, studies have shown that when such material transport systems are installed at mine depths with virgin rock temperatures (VRT) above 40oC, the heat dissipated by the conveyed ore can account for over 50% of the underground heat-load (Pareja, 2000; Bluhm, Jones, Moreby, & von Glehn, 2012; van den Berg, Moreby, & Kok, 2015).Unlike other types of heat sources encountered in underground mines, such as diesel machines, strata, electrical devices, and autocompression, heat transfer by conveyed broken rock is much more difficult to estimate. The seminal work of McPherson (1993) states that broken rock heat transfer is a function of its surface area, and the air’s psychrometric condition. It is additionally a function of the VRT, its specific heat, production rate, heat transfer coefficient and the residence time (Bossard, 1997; Ross, Tuck, Stokes, & Lowndes, 1997). Consequently, few studies have attempted to analytically quantify the significance of ore heat flow."

Jan 1, 2019

By R. C. Urquhart, D. D. Howat, R. I. L. Guthrie

Heat losses from ladles during teeming by R. C. URQUHART, M.Eng. (McGiII), Ph.D. (Visitor). R. I. L. GUTHRIE, B.Sc. (Eng.) (London), A.R.S.M., Ph.D., D.I.C. (Visitor), and D. D. HOWAT, B.Sc. (Glas.), Ph.D. (Fellow) In an investigation of the loss of temperature by liquid steel during a teeming operation, a numerical technique was used to calculate the heat flows and the rate of temperature drop over the entire teeming operation. The calculations show that, before teeming, approximately 50 per cent of the heat loss is into the ladle wall at the level of the metal. As teeming progresses, the amount of heat lost by radiation to the wall above the metalline increases. The effect of variables, such as initial metal temperature, the preheat of the ladle and ladle cover, and delays, on the rate of temperature loss by the metal were determined.

Jan 11, 1973

By Pan Gu, Zhen Zhang, Jiang Diao, Bing Xie, Hongyi Li

Furnace refractories are in most cases chemically incompatible with smelter slag, which leads to a steady erosion in their thickness over time. Once too thin, refractory walls become mechanically unstable and catastrophic failure can result. Historically, external shell cooling was applied to generate a freeze lining of slag and thus prevent refractory erosion. Many modern high intensity smelting furnaces instead maintain their physical integrity by the use of internally cooled wall panels, plates or finger coolers. An initial refractory lining is often installed inside of the coolers, such that the furnace originally operates with a temperature (insulated) rather than a heat flux (freeze lined) boundary condition. This paper examines the change in slag-wall heat transfer coefficient and slag superheat as a function of process intensity. The implications of the changes in heat transfer on residual brick thickness are explored using analytical modelling.

Jan 1, 2016

By E. Talebi, P. Roghanchi

"This study aims to discuss personal and behavioral parameters contributing to heat-related accidents. To study the prevention approaches, it is essential to look at the various factors at the individual, management, and industrial levels. Qualitative risk analysis methods are used based on the public data in the USA to find the impact of the environmental and behavioral parameters on the heat stress and heat strain of mine workers. The effects of individual factors such as worker experience, age, fitness, lifestyle, acclimation, and more are illustrated. The significance of factors such as the roles of the mine management and regulatory agencies are addressed.INTRODUCTIONOccupational hazards in mining industry endanger the health and safety of the workers and productivity loss for mining companies. Among those hazards is the exposure to excessive heat that has adverse effects on the health of mine workers. The intensity of heat load is a significant factor in fatal and non-fatal heat-related accidents. Severe environmental conditions combined with a high level of activity in the mining industry increases the vulnerability of individuals to health and safety hazards (Ngwenya, Oosthuizen, Cross, Frimpong, & Chaibva, 2018). Lack of regulations and legislation addressing the heat issue in the mining industry (i.e., underground and open pit mines, processing plants) also raises widespread concerns.Along the climate change, various sources contribute to the overall heat load at a mine site (Hanna, Kjellstrom, Bennett, & Dear, 2011; Kjellstrom, Lemke, Hyatt, & Otto, 2014). In underground mines, the majority of heat comes from different sources such as geothermal gradient, equipment, auto compression, groundwater, and blasting (Maurya, Karena, Vardhan, Aruna, & Raj, 2015). On the surface, however, the majority of heat load can be sourced to solar energy. The exposure to excessive heat might result in heat-related illnesses, fatigue and fainting, loss of concentration, performance reduction, and production loss (Kocsis & Sunkpal, 2017; Roghanchi, 2017). The severity of the effects depends on duration and level of exposure and the response of an individual to heat stress. The response of an individual is influenced by different factors including age, gender, fitness, lifestyle, experiences, and past medical history."

Jan 1, 2019

By M. L. Joy

The heat pipe is a self-contained, passive structure that uses a liquid-vapour fluid cycle to provide high thermal conductance . Through the proper selection of working fluids and container materials, heat pipes have been operated at temperatures ranging from less than -300°F to more than 3,000 °F. The passive nature, high efficiency and configuration flexibility of the heat pipe are presented. The application of McDonnell Douglas Astronautics Company Cryo-Anchor® heat pipes for foundation and support stabilization in permafrost regions is discussed. Using the proven Cryo-Anchor technology base. a proposed application of heat pipes in a cold -region mine ventilation system heat recovery heat exchanger is presented. Information obtained from the development of an air-cooled heat pipe steam condenser provides the technical basis for large -scale heat pipe applications.

Jan 1, 1978

By W. D. Bonisteel

In 1976, Rio Algom Limited began the expansion of uranium production facilities at Elliot Lake. Quirke Mine was the only property in operation at the time, and plans were made to expand its milling capacity from 4,500 to 7,000 tons of ore per day. Following this expansion, other properties in the area will be reactivated to fulfill long-term contracts for uranium. As part of the expansion program, it was decided that in view of the escalating cost and impending shortage of energy, heat reclaim and conservation would be employed wherever practicable. In general terms, heat reclaim applications fall into three main classifications: ventilation, utility and process. Two of the ventilation applications and one process application will be described in some detail. Several other systems will be presented briefly as a matter of general interest. Some future possibilities will also be mentioned, together with their potential for economical heat recovery.

Jan 1, 1979

By Yongqi Sun, Zuotai Zhang

Hot slags, at the temperatures of 1450-1650 oC, carry a substantial amount of high quality thermal energy, which represents the largest undeveloped energy source in the steel industry. However, the waste heat recovery rate in China is less than 2%; thus there is a great potential of waste heat recovery. In this study, we investigated a chemical method to extract the waste heat from high temperature blast furnace slags, i.e., sludge gasification. Sewage sludge, another substantial waste produced in the municipal system, need to be timely disposed, the organics of which could be gasified using the waste heat in the slags for the purpose of syngas production. Both the kinetics and thermodynamics of the sludge gasification process were clarified here. Most importantly, an integrated system composed of multiple systems such as the steel industry, the cement industry, the municipal system and the chemical engineering industry, was analyzed in this study.

Jan 1, 2016

By Matthew D. Viergutz

MECS? HRS technology has reliably recovered intermediate pressure steam from sulphuric acid plants for more than 20 years. This steam can either generate electricity or replace steam produced by an existing fuel-fired boiler. As worldwide greenhouse gas emissions continue to rise, industries are looking for novel and cost effective solutions to reduce pollution, particularly carbon dioxide, from their plants. Waste heat recovery technologies such as HRS offer new and existing plants the opportunity to maximize energy efficiency while reducing their reliance on energy supply from external sources. This paper offers a unique look at energy recovery in sulphuric acid plants and how recent innovations in MECS? Heat Recovery System technology make HRS more financially viable ? and more green - than ever.

Jan 1, 2009

By Matthew D. Viergutz

MECS? HRS technology has reliably recovered intermediate pressure steam from sulphuric acid plants for more than 20 years. This steam can either generate electricity or replace steam produced by an existing fuel-fired boiler. As worldwide greenhouse gas emissions continue to rise, industries are looking for novel and cost effective solutions to reduce pollution, particularly carbon dioxide, from their plants. Waste heat recovery technologies such as HRS offer new and existing plants the opportunity to maximize energy efficiency while reducing their reliance on energy supply from external sources. This paper offers a unique look at energy recovery in sulphuric acid plants and how recent innovations in MECS? Heat Recovery System technology make HRS more financially viable ? and more green - than ever.

Jan 1, 2009

By T. F. Witherbee

THE following calculation of heat requirement covers the working of the furnace from January 25th to February 14th, inclusive. A short time previous to the first date the furnace had been working rather badly, so that 300 lbs. of ore and 500 lbs. of limestone were taken off. Within the time mentioned the quality of the iron passed

Jan 1, 1877

By Alberto Pesamosca

The paper presents the results obtained by the AC EAF supplied by Danieli at Kroman Çelik (Gebze-Turkey) after the planned upgrade to 150 ton. The EAF – 7,4 m diameter, based on the full platform standard design - is able to handle a maximum power of 114 MW and is equipped with the most advanced and reliable technology, including module injection system and the Hireg electrodes regulation system. Excellent results were already obtained with 120 heat size in terms of fast start-up and excellent performance figures. After the upgrade, productivity was increased up to 212 t/h, maintaining high process efficiency (365 kWh/t with 32,1 Nm3/t O2).

Jul 30, 2018

By Paloma Lazaro, Moe Momayez

Interactions between human beings and their work environment require the body to regulate its temperature by balancing heat production and loss. Comfortable environmental conditions are crucial for keeping workers safe and healthy and to maintain a suitable level of productivity. However, achieving a proper core body temperature may become challenging under different conditions, especially in high heat-generating workplaces such as hot underground mines. Because hot underground mines have the potential to expose workers to heat stress, compliance with standardized and regulated indices and criteria is distinctly required. The objective of this paper is to provide an overview of the current research on heat stress and strain in hot underground mines, collected from published and specialized literature. General definitions, statistics of heat-related accidents in mining, overview of the indices, standards, and recommendations for heat stress are provided herein.

Oct 6, 2020

By Siddhartha Roy, Hemant Agrawal, Ram Madhab Bhattacharjee, Devi Prasad Mishra

Heat stress is a major concern for the health, safety and productivity of miners working in hot and humid underground mines. At greater depth, heat inside underground mines increases due to geothermal gradient, heat released from high-capacity machinery, exposed rock surface, auto-compression of air, human metabolism, etc. Prolonged physical work in thermal environments severely affects the health, safety and efficiency of miners. In order to address this important issue, a systematic literature review (SLR) has been conducted. This SLR aimed to identify the research gap in the area of heat stress effect on underground miners and its control. An extensive literature search was carried out on numerous digital databases, grey literature and conference proceedings to identify relevant research work for this review. Moreover, the impactful studies, methodologies and preventive measures undertaken during the past five decades on the effect of heat stress on underground miners were retrospectively analysed, with a broader aim to explore the need for further research on this pertinent topic. Overall, 571 references were identified from the literature review, out of which 51 research articles addressing the sources of heat, heat stress effects on miners, heat stress indices and control measures for heat stress in underground mines were selected as primary papers for detailed review. Pre-developed fatigue is one of the prime causes of health hazard, safety and productivity loss of miners working in underground high heat stress zones. Hence, development of a better heat stress index integrating personal, environmental parameters and pre-developed fatigue (PDF) of miners is essential.

Jan 14, 2022

By P. C. Schutte, A. J. Kielblock

INTRODUCTION Certain activities, such as emergency work and rescue operations, often have to be undertaken in environments where heat loads often exceed limits prescribed for routine work. This is particularly relevant to the South African mining industry where heat stress-induced fatalities are not uncommon during rescue operations. In this regard an excessively hot environment is defined as one where either the dry-bulb temperature exceeds 37,0°C or the wet-bulb temperature exceeds 32,5"C, and it is therefore not surprising that heat stroke mortality escalates rapidly when these limits are exceeded. A review of both local and international standards indicated that the available information on safe exposure times under abnormal heat stress conditions is very limited. Where available, such standards are aimed at the general population, including both sexes, irrespective of age and also the least heat tolerant worker, and not at a medically-screened, all-male population free of grossly heat intolerant individuals, as is the case in the South African mining industry. It is suggested that available norms and limits are too conservative for local application and, therefore, unrealistic. In view of the definite need to protect workers when exposed to abnormally high environmental temperatures, the present study was undertaken to establish a scientifically derived data base. applicable to local conditions, to determine safe exposure times: Any exposure limit, especially in an emergency situation, should be easy to administer, valid and reliable. These aspects, there- fore, form an integral part of this paper. FORMULATION OF HEAT STRESS LIMITS The formulation of heat stress limits was based on the criterion that a heat exposed individual should experience a negligible risk of developing dangerously elevated body temperatures. In order to provide a database for risk assessment, certain physiological responses of heat tolerant men were determined at various combinations of thermal conditions and work rate in a climatic chamber. These physiological responses were analysed statistically in order to predict safe survival and tolerance times as a function of thermal conditions and work rate. EXPERIMENTAL DESIGN A total of 202 randomly selected, medically fit mine workers volunteered for the study on the basis of informed consent. These men were considered to be inherently heat tolerant in as far as they had successfully completed a heat tolerance test (Anon., 1991) or the standard climatic room acclimatisation procedure used on many South African gold mines (Anon., 1989). The subjects were allocated randomly to 14 experimental groups and each group was exposed in a climatic room to one of

Jan 1, 1997

By J. M. Stewart

Although the incidence of heat stroke in South African gold mines is small, work continues on its reduction. This paper proposes limits of heat stress that are applicable to South African underground conditions, with the warning that they should not be extrapolated to other situations without careful consideration having first been given to their limitations. These limits of heat stress take physical and physiological considerations into account, and they correspond to there being a 10-6 risk of an essentially nude man developing a rectal temperature in excess of 40°C. It is recommended that further work should be undertaken on the development of equations for the calculation of the heat transfer from clothed men, the derivation of equations that quantify the physiological conductance and sweat rate response of humans, and on establishing the frequency distributions that describe variations in rectal temperature response between individuals in different types of environment.

Jan 1, 1981