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By Harald Ulrik Sverdrup, Anna Hulda Olafsdottir

The long-term supply of nickel to society was assessed with theWORLD7 model for the global nickel cycle, using new estimates of nickel reserves and resources, indicating that the best estimate of the ultimately recoverable resources for nickel is in the range of 650–720 million ton. This is significantly larger than earlier estimates. The extractable amounts were stratified by extraction cost and ore grade in the model, making them extractable only after price increases and cost reductions. The model simulated extraction, supply, ore grades, and market prices. The assessment predicts future scarcity and supply problems after 2100 for nickel. The model reconstructs observed extraction, supply and market prices for the period 1850–2020, and is used to simulate development for the period 2020–2200. The quality of nickel ore has decreased significantly from 1850 to 2020 and will continue to do so in the future according to the simulated predictions from the WORLD7 model. For nickel, extraction rates are suggested to reach their maximum value in 2050, and that most primary nickel resources will have been exhausted by 2130. After 2100, the supply per capita for nickel will decline towards exhaustion if business-as-usual is continuing. This will be manifested as reduced supply and increased prices. The peak year can be delayed by a maximum of 100 years if recycling rates are improved significantly and long before scarcity is visible.

Jan 26, 2021

By F. G. Heivilin

There will be 3 billion people moving into cities by 2050. Permitting is both the biggest obstacle and the biggest opportunity for mining. The problem is not if we have the right minerals, but how we can permit and produce it in a ?Sustainable? manner. A ?Permit? and a ?Sustainable Development Plan? may soon be the same thing. How do we produce the minerals we need with: 1. The lowest possible carbon footprint. 2. Social license from community outreach by being a catalyst and not a problem in a ?Green World.? 3. Enhanced water supply during all stages of production. 4. Meeting requirements of our customers for service, quality, & cost. How important is it to have a complete ?Sustainable Development Program?? First, no plan is complete!!! It is a work in progress subject to continuous improvement. We need to work together to get the results we want. The goal of the world communities is to become carbon neutral by 2050. What is the mining community?s goal? Do we have one???? When a Clorox, Colgate Palmolive, Wal-Mart, Toyota, or Caterpillar buys a product, what are your chances of getting an order without a good program in place? The answer is it will be difficult or impossible shortly and you will be requiring the same thing with your suppliers. This is an opportunity if you are in the lead and it soon will be a necessity for most mining and processing companies requiring much extra effort to catch up. For some mines it was a necessity to get most of the SD plan to get permitted. The number of companies in the extractive industries with a full Sustainable Development Programs is expanding rapidly as shareholder demands for transparency continue to grow.

Feb 27, 2013

By James P. Cooney

What is required for the mining industry to grow and prosper in a politically challenging world? The answer to this can be summarized as “the industry’s three priorities.” The first priority is gaining access to the world’s mineralized jurisdictions. The second is establishing a measure of security and predictability in government treatment of mining. Confidence in the stability of the fiscal and legal framework within which mining operates is necessary to encourage the investment of large amounts of capital in mine development. The third priority is sustaining the industry’s welcome during the long term in those jurisdictions worthy of investment.

Jan 1, 1996

By Tassos Grammatikopoulos, Mike Johnson, Niels Verbaan

Seabed polymetallic nodules, which contain significant quantities of metals key to electrification (nickel, cobalt, copper, and manganese) can be processed using several different metallurgical processing options, including direct smelting and subsequent hydrometallurgical refining of the copper/nickel matte, ammoniacal leaching (gas reduction or Cuprion), and acid leaching (often reductive). Many of these approaches suffer from reduced cobalt extraction, difficult physical performance, or overall circuit complexity in general, leading to increased risk to the overall project. SGS has considered pressure acid leaching of nodules for further investigation, as publicly shared data on this processing route stems from the 1970s and 1980s and is not always easily accessible. This paper will detail the series of tests conducted and provide updated results obtained (high Ni/Co/Cu recovery with limited Mn/Fe), as well as comment on the potential treatment options on the product solution and residue.

Feb 1, 2025

By Greg Colzani, Emily Thompson

The 3RPORT Project, includes a 5-mile tunnel excavated by a 19-foot diameter slurry Tunnel Boring Machine below the city of Fort Wayne, IN. The Geotechnical Baseline Report (GBR) indicated vuggy to massive argillaceous dolomite within the tunnel alignment. During excavation of the first reach, the TBM encountered zones of cohesive clay and sandstone presented in full face and mixed face conditions. The occurrence of Sandstone was not a “Baselined Condition” described in the GBR for this reach of the alignment. This paper will discuss the methodology to investigate, mitigate and evaluate the DSC impacts on TBM performance.

Dec 1, 2022

By S. Mafi

The Broken Aro project is associated with a 1910 abandoned underground mine complex that has been discharging aeid mine drainage from entries, seeps and springs. The Ohio Department of Natural Resources(ODNR), R&F Coal Company (R&F) and American Electric Power (AEP) are involved with this unique project that will remine the abandoned underground complex and install a mine seal constructed of fixated flue gas desulfurization (FGD) material. The goal of the project is to eliminate or reduce the acid mine drainage that is discharging into the watershed. This paper discusses remining, installation of the FGD mine seal, government financed reclamation projects and future application to active and abandoned mining sites.

Jan 1, 1998

By Lana Alagha, Fardis Nakhaei, Jose L. Corchado-Albelo

Tellurium (Te), a critical mineral for solar energy technologies, faces supply risk challenges that drive the development of diversified and robust production routes. This research focused on improving Te enrichment from copper tailings (CT) produced from copper porphyry (CP) ores processing, addressing the loss of ~90% of Te minerals to tailings in the flotation process of CP ores. Gravity separation and froth flotation processes were used as possible enrichment routes of Te-bearing minerals (i.e., pyrite) in CT. In the froth flotation process, synergistic combinations of reagents were tested to achieve an acceptable enrichment ratio of Te minerals. Comprehensive characterization analyses showed significant Te enrichment in the flotation concentrates. Tellurium was recovered at 90%, while the grade of Te in the concentrates was 1.4 ppm using a xanthate collector and glycol frother compared to <0.5 ppm in the flotation feed. Findings showed that Te-minerals’ enrichment was also feasible in CT using the proposed combined concentrations routes (i.e., gravity separation followed by froth flotation) by looking at Fe, Cu, and S enrichment. This study also highlighted the importance of understanding the deportment of Te minerals in different process streams to develop and optimize efficient enrichment practices.

Feb 1, 2024

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 William D. Cassity, Batric Pesic

Introduction Gold mining on an industrial scale is becoming increasingly dependent on low-grade refractory sulfide ores that contain large amounts of pyrite (FeS2) and arsenopyrite (FeAsS). Gold is usually present as sub-microscopic particles dispersed evenly throughout the sulfide matrix. Without some form of preoxidation, efficient recovery of this finely disseminated gold through cyanide leaching is hampered because the surface of the sulfide particle becomes passivated and impervious to penetration of the cyanide. Traditional methods for recovery of refractory gold from arsenopyrite ores include roasting and autoclave leaching. A modem alternative method is to preoxidize the mineral using the bacterium Thiobacillus ferrooxidans prior to attempting to re- cover the gold through cyanidation. The bioleaching of arsenopyrite ores presents a problem in the mobilization of large quantities of arsenic, present both in the +5 and +3 ionic states. Dissolved arsenic species pose a dual problem: they are -1 to the bioleaching process itself through inhibition of bacterial activity, and they also pose an environmental threat. The arsenate anion (AsO2) has been shown to be more toxic to living organisms, including Thiobacillus ferrooxidans, than the arsenate anion (AsO43) (Collinet and Morin, 1989). There is some disagreement as to the fate of arsenite in bioleaching solution. Mandl, Matulova, and Docekalova (1992) reported that dissolved arsenite concentration was constant during a long-term bioleaching study of chalcopyrite using Thiobacillus ferrooxidans. Torma and Oolman (1992) report that Thiobacillus ferrooxidans has been found capable of oxidizing As3+ to As5+. The solid products of arsenopyrite/pyrite bioleaching include jarosite (MFe3(SO4)2(OH)6 where M can be K+, Na+, NH4+ or H3O+), scorodite (FeAsO4.2H2O), ferric hydroxides, and ferric hydroxysufites (Carlson et. al., 1992; Van Breemen, 1982; Lazaroff et. al., 1982). The particular species formed is a function mainly of pH. Little study has been performed on the effect of solid products on bioleaching. Pesic and Kim (1993) showed that Thiobacillus ferrooridans cells served as a nucleation sites for jarosite particles, which grew rapidly and eventually killed the cell. Most bioleaching studies are performed at low pH&apos;s (<2.0) under uncontrolled conditions. By studying bioleaching of arsenopyrite under controlled pH conditions and at higher pH&apos;s (2.0 to 3.0), the distribution of iron and arsenic between the solid and liquid phases can be controlled, and their effects studied. The objective is to develop a bioleaching process that operates at high efficiency while keeping amounts of dissolved heavy metals low. Pesic, Stohok, and Torma (1993) demonstrated the usefulness of this approach in the leaching of cobaltite (CoAsS) concentrates. Materials and Methods The focus of this study was the bioleaching of arsenopyrite ore by Thiobacillus ferrooxidans. The parameters studied included the effects of pH, and the effects of arsenate (AsO43 and arsenite (AsO2). pH studies included pH set initially but not controlled, and pH controlled continuously with NaOH or LiOH. Bioleaching results from two strains of Thiobacillus ferrooxidans with different adaptation histories were compared. Bioleaching experiments were conducted in 150 ml stirred glass reactors using a strain of Thiobacillus ferrooxidans adapted to arsenopyrite ore, supplied by the U.S. Bureau of Mines. These bioreactors were innoculated with stock cells grown on arsenopyrite ore for 14-16 days. Typical elemental breakdown for this ore was: As, 9.90%; Fe, 18.60%, Stot, 9.26%; Suifide, 7.50%; SiO2, 25.90%. Mineralogically, the ore contained both arsenopyrite and pyrite. Bioleaching efficiency was measured by withdrawing bioleach solution samples at selected intervals, filtering, and measuring the amount of dissolved cobalt, iron, and arsenic by atomic absorption spectroscopy. Because the precipitation of iron and arsenic at higher pH&apos;s would lead to unreliable results, a 100 mg tracer of cobaltite concentrate from the Blackbird mine in southern Idaho was added to solution. Dissolution of the cobaltite tracer was used to indicate bioleaching of the bulk arsenopyrite ore. Cobalt has been shown to be stable in solution even when iron and arsenic were precipitated (Pesic, Storhok, and Tonna, 1993). The pa-

Jan 1, 1995

By Joern Katzer

It is vitally important to any tunnel project to have an accurate and reliable survey control network inside the tunnel for layouts, as-built surveys, and to provide guidance to the tunnel boring machine (TBM). However, the concepts and methodology to provide such a survey network are sometimes not well understood. For example, the first anticipated survey task that takes place during the bidding process is often ignored, which is to provide a comprehensive survey network preanalysis for the surface network and tunnel traverse based on survey statistics that will be used to make informed decisions on the survey requirements and methodology. Instead, these steps are often only vaguely based on previous results and prior tunneling experience. But each tunnel is different, and a solution that worked for one tunnel project might be unsuitable for another. The purpose of this paper is to provide tunnel project engineers, managers and surveyors with the general concepts for tunnel survey methodologies and examines several statistical tools for a basic horizontal and vertical tunnel survey preanalysis. These survey statistics tools provide useful estimates of the expected lateral and vertical tunnel traverse accuracies, but are not a replacement for a comprehensive tunnel network preanalysis. The proposed formulas do not take centering errors into account, are using average distances for each traverse leg, and assume that the survey data is free of outliers in the measurements. It is very important that the estimated instrument accuracy is based on true values that are reflective of measurement precisions that are actually achievable inside the tunnel to provide accurate results.

Dec 1, 2022

By Frederick J. Murrell

No other region of the world is enjoying the tremendous growth of power use that is currently being experienced in Asia. Fortunately for the coal industry — particularly in Asia — the power plants being planned or under construction are designed to use coal as fuel. This has produced a significant increase in the demand for steam coal that, in turn, has encouraged many in the industry to develop new coal mines. Indonesia is a country that has enjoyed substantial growth in coal production. This developing country has 195 million people who live on the nearly 13,000 islands. It has quickly emerged as the third-largest exporter of steam coal, following only Australia and South Africa. Almost all coal in Indonesia is mined by surface-mining methods.

Jan 1, 1996

By R. E. Lindstrom

The mineral bastnasite is utilized to describe alternate processes for the extraction and separation of the rare-earth elements by solvent extraction. The rare earths can be acid-leached directly or fused with NaOH before acid leaching. Cerium, the major constituent, can be recovered by fractional precipitation, fractional leaching, or solvent extraction with tri-nbutyl phosphate. The latter process is capable of producing 99.5-percent pure CeO2 at 98+ percent recovery. Lanthanum is subsequently recovered by fractional precipitation or solvent extraction with a nitrogen-based extractant. A 20-stage mixer-settler operation with a primary amine extractant results in a 95-percent pure La203 fraction at 96 percent recovery. Europium is amenable to extraction from most of the remaining rare earths with an organophosphate extractant. Selective stripping of the europium, followed by reductive precipitation, produces high-purity Eu203. Another possibility for europium purification involves the differential extraction of europium with an amine followed by a sub- sequent reducing strip. Separation of the remaining elements is more difficult but can be accomplished with amine or quaternary ammonium extracts. Typical separation factors achieved are 3. 8 for praseodymium-neodymium and 10. 5 for neodymium-samarium.

Jan 1, 1967

By Sabina Brady

Nearly a decade and a half after the US and China established formal diplomatic relations, and two decades after the two countries signed the Shanghai Communique and established commercial ties, the world, and perhaps China itself, has discovered that a wealth of natural mineral and energy resources lie beneath China&apos;s soil and directly off its coast. The country&apos;s coal reserves and oil and gas potential are well known. Its ferrous and nonferrous metal reserves are respectable and in a number of instances pre-eminent. According to 1981 Minerals Yearbook estimates - more often than not below those now being claimed by China - the country&apos;s aluminous metal reserves are about 907 Mt (1 billion st); iron ore reserves are 40 Gt (44 billion st); and copper reserves are about 46 Mt (54.4 million st) of contained metal. In addition, the country has about 10.7 Gt (11.8 billion st) of phosphate reserves, the fourth largest in the world, and 3 Gt (3.3 billion st) of pyrite. China&apos;s national Sixth Five Year Plan promulgated in late 1982 ended a stringent three-year retrenchment or readjustment period in which a number of major development projects involving foreign participation initiated in the late 1970s were shelved. The new Five Year Plan is a signal both within and outside of China that things are now moving again, and that major industrial and service sectors are receiving the kind of funding and flexibility they need for expansion, construction and modernization. The new plan&apos;s strategy for growth is measured and much less grandiose and frenetic than it was five years ago when China flung open its doors to foreign companies and invited participation in large-scale development projects. Now, the country&apos;s reticence to spend foreign exchange to purchase key equipment, technology, and services -a reaction to these projects and the spending they entailed - is clearly on the wane. In China&apos;s effort to quadruple its GNP by the year 2000, there is a new willingness to use some of its substantial foreign reserves. In fact, it is projected that 1983 will witness a $1.9 billion deficit, with a $2-3 billion deficit in 1984 and 1985. The following article discusses implications the Sixth Five-Year Plan has for nonferrous metal development in China. It is the first in a series of three articles on Chinese mineral resource development to be published in Mining Engineering over the next few months. The second article will identify specific nonferrous projects underway, while the third in the series will focus on trade and development opportunities for phosphate and potash producers in China. China&apos;s Ambitious Plans In the last few months, the exploitation of China&apos;s nonferrous resources and development of its industrial processing capabilities have begun to receive increasing attention on both provincial and central levels. Unlike the earlier modernization drive of 1978 when China&apos;s ferrous sector - best typified in the Baoshan iron and steel project - got the lion&apos;s share of the Ministry of Metallurgical Industry&apos;s (MMI) energy and resources, it now appears that in some respects the nonferrous and industrial sectors are finally moving out from beneath the dominating shadow of ferrous and getting their own day in the sun. Separation of Nonferrous from Ferrous One clear demonstration of this is the establishment in April 1983 of the China Nonferrous Metals Industry Corporation (CNFMIC). The corporation is composed of 819 enterprises with over a million workers, and also includes 12 nonferrous metal construction companies, eight design institutes, and three prospecting companies. Of ministerial rank, CNFMIC is responsible for the development of both the country&apos;s nonferrous resources and its processing facilities. Although closely tied to the parent ministry from which it sprang (i.e. MMI), CNFMIC, at least theoretically, is separate and independent from it. One strong indication that this independence is, or soon will become a reality, can be seen from the fact that the new corporation is not headed by the former MMI officials, not even those who made up the ministry&apos;s now defunct nonferrous bureau. Instead, its president Qiu Chunfu is formerly of the State Economic Commission and the China International Trust and Investment Corp. Its general manager Fei Ziwen, an engineer in his early 50s, is from the Jiangxi Province Copper Corp. The new nonferrous corporation appears to be powerful

Jan 7, 1983

By G. Duncan

Distinct trends in grinding mill technology have emerged in recent years. In an effort to optimize overall mill performance for the needs of the End User, broad measures of logistical speed, process flexibility, operational risk, and overall costs now exert greater influence on the specification of grinding equipment. As a result, innovative alternatives to conventional grinding mill structures, supports, drives, feed, and discharge configurations are now being offered and selected with greater frequency. This paper investigates these trends in grinding mill technology, utilizing optimization and decision-theory techniques. In particular, the paper considers how specific advances in process design, product engineering, manufacturing techniques, and mining operations continue to relax technological constraints, enabling further mill innovation. In this context, a methodology is presented, illustrating how proper selection and specification of grinding mill components and configuration can target an optimization of the four End-User performance measures listed above..

Jan 1, 1999

By Dong Yang, Jicai Han, Xiaoshuang Guo, Tichang Sun, Zhengyao Li

Straw charcoal was used as a novel reductant in the co-reduction roasting of laterite ore and red mud. The influence of the reductant dosages, co-reduction temperature, and co-reduction time were investigated. Results showed that a powdered ferronickel product of 1.81wt.% nickel and 81.40wt.% iron was obtained under straw charcoal dosage of 15wt.% and roasted at 1250 °C for 80 min. The corresponding recovery of nickel and total iron were 97.21wt.% and 98.87wt.%, respectively. The performance of straw charcoal was also compared to that by the conventional coke reductant. Results showed that ferronickel particles using straw charcoal were larger in size than coke, mainly due to the lower S (0.14wt.%) and ash content (3.80wt.%), which could not hinder the agglomeration of the ferronickel grains, and lower melting point that producing liquid phase and promoting ferronickel particles growth. In addition, the gasification reactivity of straw charcoal is better than that of coke, which is beneficial to the iron oxide reduction and the recovery of iron. To conclude, straw charcoal is a promising reductant for the co-reduction of laterite ore and red mud in coal-deficient areas.

Aug 12, 2021

By Yao Yevenyo Ziggah, Victor Amoako Temeng, Solomon Evans Kweku Koomson

Tyre hours/life deficit is a major operational challenge facing the mining industry which adversely affects materials production and costs. An accurate forecast of the tyre life is key in addressing this menace. This study for the first time employed the hybrid intelligent technique by utilising three metaheuristic optimisation algorithms, including particle swarm optimisation (PSO), genetic algorithm (GA), and whale optimisation algorithm (WOA), as trainers for the parametric weights and biases to optimise multilayer perceptron neural network (MLPNN) for enhancing prediction of on-site dump truck tyre life in the mine. Four hybrid models known as PSO-MLPNN, WOA-MLPNN, GA-MLPNN, and BP-MLPNN were developed using a total of 157 tyre dataset records obtained from a surface mine in Ghana. In assessing the prediction performances for the models developed, five statistical performance metrics of variance accounted for (VAF), Nash–Sutcliffe efficiency index (NASH), coefficient of determination (r2), mean absolute percentage error (MAPE), and correlation coefficient (r) were utilised. Moreover, ranking, uncertainty analysis and Bayesian information criterion (BIC) techniques were utilised to establish the most effective hybrid model, whereas sensitivity analysis was conducted on the input parameters. Results achieved showed that PSO-MLPNN was the best for prediction because it had the least MAPE value of 1.196% and relatively high values of VAF (99.642%), NASH (0.996), r2 (0.996), and r (0.998). Besides, PSO-MLPNN had the best selection criteria values of 6, 7.1725, and 444.834 for the ranking, uncertainty analysis and BIC respectively. Hence, PSO-MLPNN is recommended for the prediction of on-site dump truck tyre life for the studied mine.

Mar 11, 2024

By X. F. Wang, K. B. Fu

"We investigated experimentally and theoretically the adhesion behavior of Acidithiobacillus ferrooxidans (At.f6) to different copper sulfides. The adsorption experiment showed cell densities of 10.74 × 106, 8.06 × 106, 3 × 106, 4.24 × 106 and 2.35 × 106 cells/cm2, respectively, on the surfaces of djurleite, bornite, covellite and chalcopyrite. The order was: djurleite > bornite > covellite > chalcopyrite. The results indicate that A. ferrooxidans has high affinity to adhering to the surfaces of djurleite and bornite in the acidic region. But the thermodynamic approach predicts that there will be no attachment of At.f6 to the surfaces of bornite, covellite and chalcopyrite. This discrepancy is due to the inadequate description of electrostatic interactions. The DLVO approach shows attachment of At.f6 to the surfaces of djurleite, bornite and covellite, and repulsion between At.f6 and chalcopyrite. The DLVO approach can explain the differences of the adhesion of At.f6 to different copper sulfides.IntroductionThe bioleaching of low-grade copper sulfides is a developing technology, and has been applied successfully to the extraction of copper from secondary sulfide minerals (Watling, 2006; Pradhan et al., 2008; Akcil and Deveci, 2010). The bioleaching of chalcopyrite is still a major challenge (Bosecker, 1997; Brierley and Brierley, 2001; Ehrlich, 2004). A study conducted at Billiton Process Research showed the following preferential order of sulfide minerals leached by mesophilic cultures: chalcocite > bornite > cubanite > covellite > pyrite > enargite > carrolite >> chalcopyrite (Dew et al., 1999). The bacteria can solubilize the valuable metals from the orebodies by the oxidation of minerals. Bacterial adhesion plays a critical role in the bioleaching processes (Chen et al., 2008; Harneit et al., 2006). Generally, bacterial adhesion can be explained by surface thermodynamics and the extended DLVO theory, in which the adhesion energy between the bacteria and mineral is calculated as a function of the separation distance (Sharma, 1999; Bos et al., 1999; Sharma and Hanumantha Rao, 2002). These methods take into account Lifshitz-van der Waals interactions, electrostatic interactions and acid-base interactions (Busscher et al., 2010). These interactions are very well understood and formulated in mathematical equations. The most important inputs in these calculations are surface energy, surface charge, electron donation and electron acceptance on the bacterial cell surface and mineral."

Jan 1, 2015

By BHAMIDIPATI S. SASTRY, ANMAYA NAIK, ASIF AHMAD, Srivatsan Jayaraman Sridharan, ADITYA PANDEY

Wet kata cooling power (WKCP) as measured by a kata thermometer is a well-known heat stress index used in the mining industry. Although, over the years, several researchers proposed different heat indices and indicated limitations of the kata thermometer, WKCP is used in the South African gold mining industry due to its simplicity and rapidity of assessment. This paper presents a comparative analysis of the newly developed empirical expression for the WKCP and some of the more commonly used empirical models. For this purpose, WKCP measurements are obtained based on experiments conducted in a low-speed wind tunnel. Based on a regression technique, the analysis presented aims to assess the disagreement between the empirical model predictions and actual measurements. The correlation is also presented between WKCP and the well-established thermoregulation models using parameters from the low-speed wind tunnel experiments, including dry-bulb temperature (Td), wet-bulb temperature (Tw), barometric pressure (P), and wind speed (v). It is found that the proposed empirical model for the WKCP represents the bioclimatic interaction quite well under the specific parameters that defines the harsh thermal environment and air condition, such as metabolic activity, clothing of the person, and the velocity of the ventilating air in which the person is working. The statistical analyses performed show that the empirical model proposed for the WKCP produces satisfactory estimates of the thermal stress experienced under lower air velocities, light clothing, and higher metabolic activity rates.

Sep 2, 2021

By P. Moran

A promising and increasingly popular tailings management strategy is to place cemented tailings underground as backfill. The placement of cemented tailings results in enhanced geotechnical stability and a purportedly more geochemically stable tailings form with lower leaching potential. Conventional subaerial tailings management can negatively affect water quality if weathering causes acid rock drainage and metal leaching (ARD/ML) to occur, whereas cemented tailings can limit leaching via porosity and permeability reductions and contribute alkalinity to limit the potential for ARD/ML. Cemented tailings backfill appears to be better, but how can this advantage be proven? Currently, cemented tailings backfill is utilized at mining operations internationally, but there is limited guidance on performing geochemical characterization and associated evaluation of the potential impacts to water quality. As a result, various approaches to simulating the leaching behavior of cemented backfill have been utilized, including some methods that are unlikely to represent weathering under site-relevant conditions. American Society for Testing and Materials (ASTM) Standard Test Method C1308-08 is a diffusion testing method initially developed to assess constituent release rates from solid nuclear waste forms. ASTM C1308-08 uses intact cylinders that more closely represent actual backfill than methods that require crushing or size reduction. It is widely believed that leaching from actual cemented tailings is controlled by diffusion through small pores that exhibit limited exposed surface area, making diffusion testing particularly applicable to cemented tailings placement.

Feb 27, 2013

By A. J. Basu

Geotechnical design plays a key role in mine design. I A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches I) judgmental, based on observational and experiential facts, 2) empirical, based on empirical design formulae, and 3) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools was addressed earlier (Basu and Kuruppu, 1995). The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing structures applicable to mining geomechnics. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis application in excavation design.

Jan 1, 1996