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By Yongsik Jeong, Kwangmin Kim

Most tailings storage facility (TSF) failures occur in active, upstream-type TSFs, often due to extreme and unexpected weather conditions—specifically, heavy rainfall and strong winds. This case study of a TSF in southern Arizona examines the use of the optimum safe beach distance (Doptimal, the optimum distance between the crest and decant pond) as a tool for monitoring geotechnical stability and reducing catastrophic failures. A digital model of the TSF was used to determine the critical beach distance (Dcritical) under normal weather conditions, and Doptimal was then determined by adding incremental distances to account for the effects of heavy rainfall (Drainfall) and strong winds (Dwind). To overcome accessibility issues, a drone was used to map the TSF geometry and create a digital model. This model served as the basis for conducting a coupled stress-seepage, finite-element (FEM) analysis with a safety factor of 2.0 to assess geotechnical stability (Dcritical). The safe beach distance increments were determined using the PMP (probable maximum precipitation) and possible maximum wind speed. Based on this analysis, the optimal safe beach distance at the study site was identified as 202.2 m. Since the current beach distance (371 m) exceeds this value, the TSF was considered to be stable and satisfied the design safety factor of 2.0. However, this distance should be reassessed periodically to account for changes in the TSF geometry and other conditions. Furthermore, it applies only TSFs that are well-managed and feature a smooth, non-undulating beach surface with a consistent slope.

By W. J. D. Stone

In 1960, Magnetics International Ltd. undertook the development of the Jones High Intensity Wet Magnetic Separator in the Americas. Magnetics International had a number of possible applications in its own projects plus the intention of developing the equipment for sale to others. It was soon recognized that no matter how innovative a piece of mineral separation equipment may be, it takes many years and much finance before it is finally accepted for large scale use. For this reason, many good ideas die in their infancy. One of the chief reasons for such a time lag between conception and large scale implementation is the usual lack of finance to construct and put into operation a large demonstration unit. Even with a large unit for demonstration, the first major user usually requires a guarantee that is not normal in accepted separation equipment. Such problems are also normally accompanied by major design changes from the first conception.

Jan 1, 1971

By Richard Snyder

Secretariat of the Coal Mining and Mining Executive Committees' of the National Safety Council (NSC) and Manager of the memberships to both Mining Sections; Senior Consulting Safety Engineer, NSC; member of several committees for consensus Standards of the American National Standards Institute (ANSI); a Certified Safety Professional (CSP) of the Board of Certified Safety Professionals of the Americas, Inc. and a chief proctor for CSP testing and certification procedures, et al. It appears that the tunneling trade is merging into its own renaissance for the decade of the 1970s', and most likely on past the year 2001. Federal interest in underground excavation, and more specifically, rapid excavation expertise has been on the upswing since the latter part of the 1960's, mainly due to the pressing national needs for more raw materials based on the rise for material goods and the projective gloom of possible power shortages. On the pure tunneling side the national needs encompass, in the mainstream of priorities, rapid transportation and water supply excavation as the two top contenders. For instance, the estimates for tunnel mileage for the period 1968-1975 are:(1) Subways---85 miles Urban Highways--- 123 miles Intercity Highways---210 miles Water Supply Routes---528 miles at a total of 946 miles of tunnels. The estimated cumulative underground excavation demand in dollar amounts for the period 1970-1989 are:(1) Construction Oriented Demand--- $35 billions Mining Oriented Demand---$34 billions (which includes the coal-oriented demand on the order of 26 billions.

Jan 1, 1997

By G. Ferrara

The paper describes the new design criteria and control strategies for multi-density dense medium separation (DMS) circuits. The role of the multi-density separation is discussed, and it is emphasized that for many processing problems -related to minerals and coals -it may be very important to perform two or more cuts at different densities in order to obtain a remarkable improvement in quality of products, process efficiency and economy. The two-density separation by dense medium cyclones was generally performed using two dense medium plants in sequence. In contrast to the former technology, the multi-density separation can now be performed by using a single medium circuit composed of different interconnected medium sumps. The sumps, one for each density, are fed with different medium streams selected according to their density, size composition and content in non-magnetic contaminant in such a way that the rheological properties of the media are optimized. This new technology is based on dynamic systems to density the medium, on the size-density segregation of the medium in the cyclones and separating devices and on accurate control systems for the density, viscosity and stability of the dense media of the different sumps. The present paper reports on the theoretical basis for the new, advanced medium circuits and on the systems for the control of the densities and of the rheological properties of the dense media. A typical circuit for a two-density separation is also described, and some industrial applications reported and discussed.

Jan 1, 1994

By Connor Langford, Murray Gant, Ken Massé

For public organizations, preparing accurate project cost estimates is a critical component in capital project planning. Project delivery methods provide a structured approach to moving projects through the design and construction lifecycle, and typically use cost estimates as key inputs at each stage to determine if the project will advance. As design stages can occur years or even decades before construction contracts are awarded, estimates need to make reasonable assumptions about how the work may be executed (means and methods) as well as potential future market trends so that appropriate values for material pricing, labour costs, escalation, and owner’s costs can be included. This process is challenging enough during stable markets, as historic trends can often be misleading and require a suitable understanding of economic factors to use appropriately. When you mix in the market volatility that has been observed since 2020, developing accurate project cost estimates becomes even more challenging. In cases such as this, having a structured approach to cost estimating that includes an adequate risk-based reserves cannot be overstated as it provides the basis for ongoing project decisions. This paper explores some of the historic and more recent market trends that have impacted key aspects of project cost estimates for capital project planning. It also provides recommendations on how to develop cost estimates for infrastructure projects, with examples from Metro Vancouver, which plans for and delivers regional-scale services to 2.6 million residents. A brief commentary on the use of escalation clauses in contracts is also presented.

Jun 13, 2023

By Tassos Grammatikopoulos, Mike Johnson, Niels Verbaan

Seabed polymetallic nodules, which contain significant quantities of metals key to electrification such as nickel (Ni), cobalt (Co), copper (Cu) and manganese (Mn) 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 the pressure acid leaching of nodules for further investigation, as publicly shared data on this processing route stem from the 1970s and 1980s, and are not always easily accessible. This article details the series of tests conducted and provides updated results obtained — high Ni/Co/Cu recovery with limited manganese/iron (Mn/Fe) — as well as comments on the potential treatment options on the product solution and residue.

Sep 1, 2025

And a new generation of safety culture experts are telling mining companies how to use it: It is a situation that is still too common in the mining industry: the latest personal protective gear is in place. The safety rules are known and followed. And then, in a moment of inattention or carelessness, a mistake is made and someone gets hurt or killed. Common wisdom claims that such accidents are impossible to eliminate entirely. Mining is dangerous, and some miners will always be hurt and killed. An increasing number of mine safety experts, however, reject the common wisdom. A year with zero mining deaths is possible, they say; with the use of one of the newest weapons to the mining industry in the safety war: the concept of safety culture. Safety culture refers to the set of attitudes, beliefs, perceptions and values that influence safety in the work environment. It is also sometimes called the way an organization behaves when no one is watching. Robert Peters, of the Office of Mine Safety and Health Research (OMSHR) at the National Institute for Occupational Safety and Health (NIOSH), describes safety culture this way: ?It?s what?s believed on a day-to-day basis. For example, if a miner sees a workplace hazard and he truly believes that his boss wants him to identify the hazard and bring it to the company?s attention, that would be an example of a positive safety culture.?

Jun 1, 2010

By Nilufer Kursunoglu

Despite being crucial for meeting the world’s energy demands, coal mining operations present considerable health risks, especially when it comes to exposure to coal dust. Longwall coal mining, an advanced technique, has considerably enhanced production but made dust control more difficult. Due to its explosive nature, coal dust continues to be a serious and dangerous concern in the industry despite developments in safety technology. This study aims to comprehensively assess the risk of coal dust explosions by integrating fuzzy risk matrix and Pareto analysis methodologies, offering precise risk ratings for various root causes. A fuzzy risk matrix was developed to assign exact risk ratings to identified root causes. Additionally, a Pareto chart was used to identify the main reasons and suggest particular preventive measures. 17 significant causes were determined for underground coal mines based on the study’s methodology, and some preventive measures were suggested. In accordance with fuzzy risk rating values, root causes were divided into six categories. The root hazard with the highest risk rating was identified as ‘accumulation of inflammable gas/gases’. The proposed approach was used to examine incidents caused by coal dust explosions in Turkish coal mines in order to demonstrate the effectiveness of combining the fuzzy risk matrix and Pareto analysis for assessing coal dust explosions. This study gives not only a solid framework for risk assessment but also critical information for classifying the risks associated with coal mine dust explosions. The results highlight the critical necessity for proactive and preventive actions to reduce the hazards of coal dust explosions and protect the safety of mining workers.

Nov 16, 2023

By Magnus Ericsson

The unexpectedly quick recovery in world crude steel production in the second half of 2009 was due almost entirely to increased production in China that began in late 2008. Previous peaks in monthly production in China were matched by April 2009. The rest of the world had still not reached pre-crisis production rates by May 2010. Chinese production drives growth, but there has been some growth in most other larger crude steel producing countries as well, compared to production in 2009. If the production rate of the first four months of 2010 continues, the total output of crude steel in 2010 will be somewhere around 1,410 Mt (1.5 billion st), the same as in the record year of 2007.

Jan 1, 2010

By Tim Neil, O&apos

Introduction On the banks of the Columbia River, about halfway between Seattle and Spokane, sits Wenatchee, WA. It calls itself "the apple capital of the world." And it has a gold mining history that dates back to the 1880s. It was just outside Wenatchee - three blocks outside, to be exact-that Asamera recently dedicated its $60 million Cannon underground gold mine. At full production, it is estimated the Cannon mine will yield between 5 and 5.6 t/a (160,000 and 180,000 oz per year) of gold. That would make Cannon the largest North American underground gold mine to be brought into production this year. Cannon should also be among the top 10 of all North American gold producers. Asamera officials project Cannon's operating costs at about $4.8019 ($150 per oz). At that rate, the mine should also be one of the lower cost and most profitable gold mining operations in North America. One reason for low operating costs is low electric power costs. The Cannon operation will be paying about 2.5 cents per kWh for hydroelectric power supplied by the Bonneville Power Authority. Proven and probable ore reserves at Cannon are in excess of 4.7 Mt (5.2 million st). Reserve grades average 7.29 g/t (0.21 oz per st) of gold in three ore zones, in order of discovery - B, B West, and B North. The ore bodies could have been mined by open-pit methods. But underground mining was chosen for environmental reasons. In addition, the rich B North ore body extends beneath a nearby horse stable and arena. The Cannon mine area comprises some 20 km2 (5000 acres) in Chelan County. The mine site is located at the 305 m (1000 ft) elevation in Dry Gulch at the base of the Cascade Mountains. The initial estimate of mine life for the Cannon operation is eight years, depending on gold prices. But Asamera officials believe the Wenatchee area has excellent potential for future gold discoveries. Asamera, Inc. of Calgary, Alberta, owns 51% of the Cannon property, through its wholly-owned Asamera Minerals (US). Breakwater Resources Ltd. of Vancouver, British Columbia owns 49% of the operation. The Cannon mine is named in honor of longtime Asamera, Inc. executive and current company director, geologist Donald G. Can¬non. It was he who first brought the Wenatchee property to Asamera's attention and urged the company to pursue it. Asamera is a major explorer and producer of oil and gas. Its Cannon operation is the largest and most significant to date in its mining division, according to Rob¬ert G. Welty. He is Asamera's chairman and chief executive officer. It should be noted there was an element of serendipity involved in Cannon's development. The development program be¬gan when geologist Cannon visited the Wenatchee area. He was visit¬ing old mining districts. He liked what he saw. The Cannon property was eventually optioned for ex¬ploration, including a modest drilling program.

Jan 12, 1985

By Shuchen Sun, Ganfeng Tu, Chuan Liu, Xiaoping Zhu

The hydrometallurgical residue generated during the hydrometallurgical processing of waste automotive catalysts is valuable as a secondary resource. In this study, a process of platinum recovery from the hydrometallurgical residue by high-temperature smelting process was proposed. Results of lab- and pilot-scale experiments show a high recovery of more than 98% of platinum and glass slag was successfully obtained by controlling the Fe3O4 addition, C/Fe3O4 mass ratio, CaO/SiO2 mass ratio, smelting temperature, and holding time at 15 wt%, 0.4, 0.6, 1500 °C, and 120 or 60 min, respectively. Results from the pilot-scale show that the platinum contents in the glass slag and alloys were less than 4 g/t and more than 0.6 wt%, respectively. Therefore, the process proposed in this study is a prospective and effective approach for reutilization of hydrometallurgical residue containing platinum.

Oct 12, 2020

By H. B. Miller

Contract Incentives have long been employed in the underground hardrock industry as a tool to influence employee performance, enhance productivity, and control labor costs. While traditionally structured to establish a direct correlation between performance and compensation, many contract programs have evolved into elaborate systems that promote strategies often viewed as independent of productivity. This paper presents the findings of research into these contract incentives and was conducted with the cooperation of 33 mines utilizing a spectrum of employee compensation and incentive programs. Emphasis of this analysis focuses on the types of production contracts observed and their role with respect to employee earnings.

Jan 1, 1994

By E. Watkins, V. Gangrade

Large-opening stone mines often rely on natural ventilation and a network of auxiliary fans to produce adequate ventilation conditions in the mine instead of main mine fans, which are commonly utilized in coal mines. Large air volumes in underground stone mines, poor ventilation practices, and low operating budgets for mine ventilation potentially increase mine workers’ risk for dust, silica, and diesel particulate matter (DPM) emissions exposure. To help improve mine ventilation practices, the optimal auxiliary fan location for maximum airflow production from a ventilated intersection was determined using a combination of field measurements and computational fluid dynamics (CFD) modeling. In this study, conducted by researchers at the National Institute for Occupational Safety and Health (NIOSH), airflow quantity and fan data were collected at a partner mine to be applied as CFD model input parameters and comparison data for model validation. A six-foot diameter auxiliary propeller fan was introduced into the validated CFD model at three locations at a mine entry intersection with established ventilation flow perpendicular to the fan direction. Placing the fan on the opposite side of the intersection from the target active face area produced the highest ventilation flow rates at the downstream locations tested and produced the lowest amount of air re-circulation. The findings show that optimizing the placement of an auxiliary fan may increase the net effective ventilation flow rate by 70,000 cfm and reduce recirculation by 26%, which maximizes the potential effectiveness of large-opening stone mine ventilation systems and decreases mine worker exposures to airborne contaminants.

Mar 2, 2022

By Nikhil Dhawan, Veeranjaneyulu Rayapudi

This study investigates upgrading of low-grade banded hematite quartzite iron ore (Fe ~31%). Conventional beneficiation was found to be futile. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. Microwave exposure of coarse particles at 540 W for 10 min yielded a concentrate with Fe 56.30% and recovery of 50.68%. Conventional carbothermic reduction at 500 °C, 60 min and 9% charcoal yielded a concentrate with Fe 57.6% and iron recovery of 68%. The presence of sufficiently bonded silica leads to an easy formation of a fayalite phase. The microwave reduction design yielded FeG of 57.6%, FeR of 47% and a yield of 24% at an optimal condition of 540 W, 8 min and 6% charcoal. It was found that a small fraction of microwave-irradiated ore-charcoal mixture melted rapidly, and pure ferrite balls were observed within 8 min. An optical micrograph of a ferrite ball reveals the retained austenite and martensite phase.

By Changshou Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,175 t (3,500 st) of ore per day with an average gold grade of 12.6 g/t (0.4 opst). The mine has a large horizontal extent of 762 by 152 m (2,500 by 500 ft) and a vertical extent of 6 to 61 m (20 to 200 ft). Based on the characteristics of the ore bodies, the deposits are divided into several mining zones. The geotechnical properties of mining zones are also different from one zone to another. A successful geotechnical collection system is very important for mining design and operation in the Leeville underground mine. Three methods are used to collect the geotechnical data in the Leeville underground mine: • Core logging. Most geotechnical data are collected by this method, which is based on exploratory drills and estimates parameters for rock quality designation (RQD), fracture frequency (FF), compressive strength and rock mass rate (RMR). • Site investigation. This method collects more detailed geotechnical data and geostructural data from work done in the underground drifts and stopes. Parameters of RQD, FF, compressive strength, RMR, rock tunneling quality index (Q) and geostructural data are estimated. • Data collected from drill holes made for the critical infrastructure facilities. This method provides the best detailed geotechnical information for areas in which the critical infrastructure located. A complete geotechnical database has been constructed using this geotechnical data collection system. The database can be used for the design of ground support, stopes and stope blasts, among other critical applications.

Jan 1, 2010

By Xin Wang, He Shao, Wenpu Li, Yiyi Zheng, Xi Chen, Yurong Gao

This study utilized experimental and numerical simulation methods to investigate and analyze the atomization characteristics of three internal air–water mixed atomizers under different operating conditions. By comparing the research results, the effective dust control working parameters for the application of the selected atomizer in the engineering field were determined. Firstly, the atomization characteristics of the three atomizers were studied using a customized experimental system. The results indicated that nozzle 2 had a wide atomization range, a small atomization distance, and small droplet size; nozzle 3 had a narrow atomization range, large droplet size, and fast atomization speed; and nozzle 1 not only had a large atomization range but also could produce droplets of dry mist size with fast atomization speed, meeting the dust reduction requirements of the Majiliang Coal Preparation Plant. Secondly, Fluent software was used to simulate the atomization process and particle size distribution of the three internal mixed atomizers, determining the working conditions of the atomizers, the required number of atomizers, and the application angle of the atomizers in the internal mixed dust removal system. Finally, the atomized dust control system was applied on-site, achieving a total dust removal efficiency of 90.72% and a respirable dust removal efficiency of 89.75%.

Mar 9, 2024

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 P. T. Bissert, L. Yan, M. D. Klein

"Since 2008, the U.S. Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines (MSHA, 2008). MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. In its 2006 report, the West Virginia Mine Safety Technology Task Force (2006) recommended an apparent temperature limit of 35 °C (95 °F) for RAs. In Title 30 Code of Federal Regulations Part 7.504, or 30 CFR 7.504, MSHA specifies a maximum apparent temperature of 35 °C (95 °F) inside an occupied RA (MSHA, 2016). The apparent temperature is calculated using both air temperature and relative humidity (Steadman, 1979).Calculations can be used to deter-mine if the air within an occupied RA will reach the apparent temperature limit. In these calculations, the mine temperature could be assumed to re-main constant. With this assumption, the effects of the mine strata thermal mass and thermal conductivity on the heat buildup in an RA are ignored. Re-search conducted by the U.S. National Institute for Occupational Safety and Health (NIOSH) shows that the mine air and strata temperatures surrounding an RA increase when subjected to the heat of an occupied RA (Yantek, 2014). Thus, calculations performed with the assumption that the mine temperature is constant would underpredict the resulting dry-bulb temperature and apparent temperature for a given RA occupancy. The mine air temperature has been used as the basis for RA temperature calculations. However, there has been no research to confirm that the mine air temperature is the appropriate basis."

Apr 1, 2017

By D. K. DeForest

The olfactory system (sense of smell) is crucial to the ability of fish to avoid predators, recognize kin, and synchronize reproduction (Baldwin et al. 2003). Copper (Cu) has been shown to impair olfaction in juvenile freshwater life stages of salmonids (including Pacific salmon and trout) in some laboratory experiments; and in the United States, public concerns have been expressed that current regulatory criteria for Cu in fresh water are not adequately protective of olfactory function in salmonids (e.g., OSU 2007; Pearson 2007). These concerns have largely been raised because some Cu concentrations that have caused olfactory impairment in salmonids in the laboratory are less than Cu concentrations that have been shown to reduce salmonid survival, growth, or reproduction (the effects endpoints that are typically considered in deriving ambient water quality criteria). However, two important and interrelated points that must be considered: (1) freshwater Cu criteria are "driven" by the sensitivities of several invertebrate species that are more sensitive than the olfactory impairment threshold in salmonids when (2) the influence of water chemistry on Cu bioavailability is properly considered in deriving Cu criteria. Bioavailability refers to the ability of various chemical forms of Cu to interact with receptors on the surface(s) of organisms and thus directly cause toxicity or uptake by the organisms. The toxicity of Cu and other metals to aquatic organisms is a function of water chemistry. For example, acute Cu toxicity in fresh water generally decreases as pH, water hardness (Ca2+ and Mg2+), alkalinity, and dissolved organic carbon (DOC) concentrations increase (Meyer et al. 2007). The U.S. Environmental Protection Agency (USEPA) has recommended hardness-based freshwater aquatic life criteria for Cu and other metals since the 1980s (e.g., USEPA 1985); and hardness-based metals criteria decrease (i.e., become more restrictive) as water hardness decreases. More recently, the USEPA has recommended freshwater aquatic life criteria for Cu based on the biotic ligand model (BLM; USEPA 2007), which accounts for the influence of multiple water chemistry parameters, including DOC, pH, alkalinity, Ca2+, Mg2+, and several other cations and anions. The BLM-based Cu criteria generally decrease as DOC concentration, pH, alkalinity, and water hardness decrease. Because DOC has a stronger influence on Cu bioavailability than water hardness, hardness-based and BLM-based Cu criteria can differ considerably. For example, in water that has low DOC and high hardness, the hardness-based Cu criterion would be relatively high (because it is driven by the high hardness) but the BLM-based Cu criterion would be relatively low (because it is driven by the low DOC). Thus, any evaluation of the protectiveness of Cu criteria against a given effect, such as olfactory impairment, must properly account for the chemistry of the exposure water. Meyer et al. (2013) compiled data on Cu-induced olfactory impairment and olfactory-induced behavioral effects from tests in which BLM parameters were measured. They demonstrated that the USEPA's BLM-based freshwater life criteria for Cu are protective against olfactory impairment, because it adequately accounts for water chemistry (whereas the USEPA's hardness-based Cu criteria are not consistently protective). Olfactory impairment by Cu is now receiving increased attention in Canada and Europe (e.g., Wall 2013; Stang 2013). Accordingly, in this paper we have expanded the analysis of Meyer et al. (2013) to consider copper guidelines from various other countries and whether these guidelines are protective against olfactory impairment.

Feb 23, 2014

By Robert C. Bates

Published information discussing uranium mine radon daughter controls and related costs was examined and used to develop an estimated (projected) cost per ton for any level of control. Results show a clear power function increase of cost for conventional dilution ventilation as the annual exposure limit is lowered. Projections can be made using any assumed changes in consumer price index (CPI) and radon daughter working level months exposure limit. Bounds on the estimated costs are provided, and applicability of the final equation is discussed.

Jan 1, 1983