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By David Morrison

"The history of the mining industry is littered with in-pit crushing and conveying (IPCC), which should not be confused with the International Protocol for Carbon Capture, projects that failed. The failure is not the technical one of “did it achieve the desired tonnage rate for a longish test period” but, rather, the far more important one of “did it provide return on the investment in the manner that was promised?” While quite a few can claim the former, very few system installations can claim the latter.The reasons for the many failures are numerous, but they are all characterized by a combination of an element of engineering optimism in any, or all of the production rates, the productivity, or the operating and maintenance costs and in predicting the continuity of operating conditions. In these days of big data, propagating such a situation is rapidly becoming unforgivable.In this article, the three most common scenarios put to the corporate board for approval, and the logic as to why they were selected, are examined (with the irony included intentionally).• Fully mobile crusher, fed by a shovel and conveyed out of the pit to a waste dump / process plant.• Semimobile crusher (much more expensive than a fixed crushing station but which apparently allows trucks to short haul inside the pit and improve productivity), which moves when the face moves.• Relocatable crusher (more expensive than a fixed crushing station but which gets relocated at great expense after all the fixed infrastructure impeding relocation is demolished) fed by trucks that don’t leave the pit mostly.This paper will also consider the truth about their operational performance and associate costs."

Dec 1, 2016

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Longwall mining is a highly productive and efficient coal mining method used in the USA. During longwall retreating, the belt entry must be maintained stable, and any roof fall in the belt entry would jeopardize mine safety and substantially interrupt the continuous production of coal in the longwall face. Past experience of longwall mining has shown that belt entry stability was the greatest challenge in longwall ground control, and the occurrence of roof falls in belt entries was largely associated with high horizontal stress. To properly support the roof in the belt entry, it is important to understand how longwall-induced horizontal stress changes affect roof stability in belt entries and to strategically install supplementary support to prevent any potential roof falls. Researchers from the National Institute for Occupational Safety and Health (NIOSH) performed horizontal stress measurements in the immediate roof of the belt entries for two Pittsburgh seam longwall panels oriented unfavorably to high horizontal stress. Hollow inclusion cells (HICells) were installed in the immediate roof at the intersection in each of the belt entries, and stress changes were monitored as the longwall face was approaching and passing the intersection. Numerical models were set up to calculate the longwall-induced horizontal stress changes in the roof at the monitoring sites. With the verified model, investigations were made of how horizontal stress is concentrated and relieved in the belt entry roof near the face under different panel orientations. Both measurements and modeling results showed that high horizontal stress is concentrated in the roof in the belt entry within about 15 m outby the face when a longwall panel is unfavorably oriented to the major horizontal stress. The study demonstrated that longwall-induced differential horizontal stress can be used as an indication of the degree of horizontal stress concentration. Roof support strategies are discussed on how to maintain the stability of belt entry under high horizontal stress concentration.

Jun 14, 2022

By YUSONG MIAO, DI WU, XIANRONG YAN, YIPING ZHANG, JIE LIN, KEBIN LI

Rock fragmentation has been a concern in hard-rock mining for the mining industry. Rock fragmentation distribution is an important index to measure the blasting effect. It not only affects the cost of drilling and blasting, but also affects the efficiency of subsequent operations, such as loading, transportation and secondary crushing.

By Roy Norcross

For the past few years Caro's acid has been used for the treatment of cyanide containing slurry effluents, providing a feasible alter­ naive to other slurry treatment processes including !NCO SO2 / Arr and ferrous sulfate. Presently, mines using Caro's acid gen­erate their own Caro's acid onsite making a relatively low quali­ty product. It was at this point where we, at Degussa Corporation, decided to focus our efforts on engineering a Caro's acid genera­tor capable of cost effectively producing a high quality Caro's acid solution, thus reducing operating costs significantly. Caro's acid or peroxymonosulfuric acid is not a new chem­ical nor is it new to Degussa. The product was named after Heinrich Caro (1834-1910), a German chemist who first described its synthesis and its oxidizing properties in 1898. Degussa has been producing the potassium salt of Caro's acid as the triple salt, 2KHSO5 - 2KHSO4 - K2SO4, called Caroat®, for over 30 years. Caroat® is used for household and denture cleansers, as a bleaching agent in dish washing detergents, in printed circuit board etching and for cyanide destruction in the plating industry. From our experience in producing Caroat® Degussa developed its new Caro's acid based DegOX™ technology for the treat­ment of cyanide containing effluents from gold and silver mines.

Jan 1, 1996

By K. A. Natarajan

The utility of yeast, Saccharomyces cerevisiae, in the separation of quartz from hematite is demonstrated. Yeast cells, as well as their metabolites, functioned as flotation collectors, depressants or flocculants and dispersants for hematite and quartz. Interaction between yeast and the above minerals resulted in significant surface chemical changes, rendering quartz surfaces hydrophobic and hematite hydrophilic. Mineral-specific extracellular proteins and exopolysaccharides were secreted by yeast cells when grown in the presence of quartz and hematite, respectively. Quartz could be efficiently separated from hematite through microbially induced flotation and selective flocculation.

May 1, 2012

By William Gleason

The Dulles Corridor Metrorail Project is a $3-billion project that will link Dulles International Airport with the downtown center of Washington D.C. by way of a single seat train ride. The project is mostly above ground, but it does include two short, yet complex, tunnels through the area of Tyson?s Corner. The project is being completed in two phases. The Dulles Transit Partners (DTP), led by Bechtel, was awarded the first phase, a $1.6-bil-lion phase that includes 17 km (11 miles) of track with five stations. At Tyson?s Corner, the project includes twin 730-m- (2,400-ft-) long, 6-m- (20-ft-) diameter tunnels. Bechtel is self-performing construction for the $1.6-billion design-build job. Gall Zeidler Consultants was hired by DTP as designer for the NATM tunnel portion of Phase 1, and Beton-und-Monierbau was hired as tunnel subcontractor. Tyson?s Corner is an affluent and congested area that sits 152 m (500 ft) above sea level. To get through the area, it was decided that tunnels would be the best option with the least amount of disturbance to the surrounding areas. However, with extremely shallow groundcover above some points as well as soft soil throughout, the tunnels are also the most complex aspect of Phase 1. About 213 m (700 ft) was constructed utilizing the cut-and-cover method. The remaining 518 m (1,700 ft) is being constructed using the New Austrian Tunneling Method, which integrates the principles of the behavior of rock and soil masses under load, and monitoring the performance of underground construction during construction. ?The tunnel only falls 2 m (7 ft) from one end to the other and we pass through two soil conditions, they are both soft ground,? said Dominic Cerulli, tunnel task manager for Bechtel. ?Soft ground is very tricky because you have to close the ring in a timely manner to minimize settlements at the surface. If you don?t close the ring quickly to achieve a round structure that?s good in compression, the tunnel could start necking and squatting and the ground above it will settle. We are under major roadways, so excessive settlement would be a bad thing.?

Jan 1, 2011

By Clive Wilson, Bruce Hutchison, Daniel N. Adams

Two three-lane highway tunnels, 700 and 2900 m long, make up the driven tunnels portion of Melbourne City Link. Tunnel construction, using design-construct delivery, commenced in May 1996. Construction required excavation through varying rock conditions; temporary support included ground freezing, pipe-spiling, steel sets, and rock bolts. Permanent support for the tunnels required both drained and undrained tunnel cross sections using unreinforced concrete. This paper reviews the construction methods, and highlights some of the not-so-standard designs developed while construction was underway.

Jan 1, 1999

By Justin R. Patts, Andrew B. Cecala, A. KYLE LOUK, Emily J. Haas

The U.S. National Institute for Occupational Safety and Health (NIOSH) and the former U.S. Bureau of Mines (USBM) have put significant effort over the past four decades into researching and developing engineering controls and interventions to reduce mine workers’ dust exposures during the bagging and palletizing of industrial minerals. Workers who perform the manual bagging and palletizing of 50- to 100-lb bags typically have some of the highest dust exposures of all workers at mining and mineral processing operations. This paper provides an overview of available dust control technologies for bagging operations and presents the findings of a recent case study conducted at four industrial sand operations to identify the current types of bagging and palletizing technologies being used and to evaluate their effectiveness in reducing workers’ exposures to respirable crystalline silica dust. An evaluation is also performed to determine if further reductions in respirable dust levels can be achieved by incorporating additional modifications or improvements into the existing technology.

The Global Mining Standards and Guidelines Group (GMSG) is building an international, multi-stakeholder community to advance the availability and use of standards and industry guidelines for the global mining community. Standards and guidelines are key strategic tools for operational excellence, enabling companies to move forward with efficient, innovative operations with reduced risk. Launched in May 2012, the GMSG is the first international center to bring together information, resources and collaborative projects for mining standards and guidelines, in an open, knowledge-sharing forum. The GMSG is supported by five partner organizations providing outreach and helping to guide GMSG activities: the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the Society for Mining, Metallurgy and Exploration (SME), the Australasian Institute of Mining and Metallurgy (AusIMM), the Southern African Institute of Mining and Metallurgy (SAIMM) and the Surface Mining Association for Research and Technology (SMART). GMSG was formed under the CIM Surface Mining Society, though its mandate extends to include underground mining as well. ?SME is supporting the GMSG as a key international activity to advance the implementation of standards and guidelines in our industry, and to provide a forum for our members to access, and contribute to, projects and information to assist their operations,? said SME Executive Director David Kanagy. ?We see the GMSG as a good example of ways the major mining associations can work together for the benefit of all our members.? The GMSG charter encompasses all standards and guidelines that apply to mining; however, a number of subject areas are now being spearheaded by six working groups, namely: ? Access and usage of data from mobile mining equipment onboard systems. ? Operational safety. ? Situational awareness (namely, a unified equipment operator interface). ? Underground operations. ? Asset management and operations data definitions and KPIs. ? Energy in communition.

Oct 1, 2013

By Edward Holloway

The basis for the selection of the ultimate pit for an open-pit mining operation is generally opaque. Some form of value-based analysis will generally guide the final decision; however, the value will often gradually plateau while the ultimate pit size continues to increase. There is no established framework to guide specialists in the selection of the ultimate pit, with such decisions regularly made on a somewhat arbitrary basis. The key component that is missing from the analyses typically used to select the size of the ultimate pit is risk. Once risk is quantified within the analysis framework, the decision-mak-ing range is significantly reduced and the process for select-ing the ultimate pit becomes more consistent, replicable and defensible. The technique outlined in this paper provides an approach to including risk in the process used to select the ultimate pit.

Jun 1, 2024

By A. J. S. Spearing, A. Mueller

The support of intersections in coal mines remains an important safety issue, mainly because the large diagonal span compromises the stability of the roof. This structural weakness is further exacerbated if the intersection is developed incorrectly, the pillar corners fail or the crosscuts are angled (not perpendicular). This report details the current support systems used and investigates unplanned falls of ground in intersections in coal mines throughout the United States. A possible failure mechanism is proposed and some suggestions are made to improve the effectiveness of the support in these vital areas.

Jan 1, 2009

By H. Kinilakodi, R. L. Grayson

In 2010, the U.S. Mine Safety and Health Administration (MSHA) began holding hearings on a new coal mine respirable dust rule, which proposed a 1.0 mg/m3 standard, a separate 0.1 mg/m3 quartz standard, and the use of single-shift samples for compliance. Small mines largely comprise the “hot spots” where dust diseases of the lungs increased dramatically over the past decade. This paper presents findings on the feasibility of small mines’ compliance with the proposed new 1.0 mg/m3 standard. It gives probabilities of noncompliance by MSHA district, average mining height and selected “hot spot” counties. Because silicosis and respirable quartz dust appear to be the primary issues related to a recent doubling of the prevalence of dust diseases of the lungs, multiple regression models for prediction of the average total quartz content of compliance samples are given. These findings have significant implications for the need for better dust control methods.

Jan 1, 2012

By Grant A. Brackebusch

Paste tailings disposal was successfully implemented at the New Jersey mill in Kellogg, ID with two different types of ore feed, a gold ore and a silver ore. The purpose of this paper is to describe the production of paste tailings, including operational problems during commissioning, and also highlight the environmental and economic benefits that were realized versus conventional tailings disposal such as the recycling of process water, increased shear strength and reduced permeability of the tailings mass, and reduced environmental permitting.

By Steve Trussell, William H. Langer

"Arizona aggregate (sand, gravel and crushed stone) producers enjoyed more than a half a century of nearly constant growth in demand for aggregates. Approximately 80 percent of the aggregate produced in Arizona is sand and gravel, and 20 percent is crushed stone (U.S. Geological Survey, 2015). Figure 1 shows the generalized distribution of potential sources of sand and gravel (yellow) and potential sources of crushed stone (other colors described below). Black dots show locations of aggregate operations.Sand and gravel commonly is produced from modern river channels and terraces although some alluvial fans and high-level paleo-river terraces also serve as aggregate resources. The gravel clasts are a mix of rock types that reflect the types of rock in the source area of the rivers. Generally processed river gravels meet stringent specifications for highend uses.Crushed stone, which makes up about 20 percent of production, primarily comes from a variety of metamorphic rocks and light-colored intrusive igneous rocks such as granite (brown areas), dark colored extrusive igneous rocks such as basalt and scoria (rust colored areas), and carbonate rocks such as limestone or dolostone (green areas). Carbonate rocks are also used in the manufacture of cement and lime.Construction and aggregate production in ArizonaBecause aggregate producers have limited facilities for storing product, stockpile changes are insignificant compared to production. Therefore, demand or consumption of aggregate in Arizona is considered to be equal to production. Production figures used in this paper reflect shipments, sales or marketable production, including aggregate used by producers to make readymix concrete and asphalt. Production figures were reported by the U.S. Bureau of Mines from 1950 until 1995 and by the U.S. Geological Survey (USGS) since then. Production figures are reported voluntarily, and major operators are the primary source for these figures. Because many smaller operators do not report their production, the figures are conservative values that provide an approximation of aggregates production activity."

Jan 1, 2015

By Charles Dumaresq

The management of mine tailings poses a complex range of potential risks, including physical risks, such as the risk of catastrophic failure of a tailings facility and chemical risks such as the risk of long-term leaching of contaminants into the downstream environment. If these risks materialize, they can lead to a wide range of impacts on people and the environment, including human fatalities and severe impacts on downstream ecosystems, and the costs of recovery borne by industry, communities, governments, and society as a whole can be immense. Tailings facility failures in Canada (2014), Brazil (2015 and 2019), South Africa (2022), and in other locations around the world underscore how high the stakes are when mines produce and manage tailings (WISE Uranium Project 2019). Understandably, many people do not trust the mining industry to manage tailings responsibly. As an industry, it is our responsibility to manage tailings in a manner that is responsible and strives to minimize harm associated with tailings management, including effectively managing both the physical and chemical risks associated with tailings. Standards have an important role to play in responsible tailings management by setting expectations for standards of care and providing a means to measure and report on performance. In jurisdictions with strong legal requirements for tailings management, standards play a complementary role, pushing performance improvements in areas that may be difficult or impossible to address in legal requirements. In jurisdictions where legal requirements are lagging, standards may represent the de facto leading practice and may be the primary tool to help ensure responsible tailings management. Implementation of standards can help companies demonstrate that tailings are being responsibly managed and help build trust and credibility. Most importantly though, standards are important tools to help ensure that the risks associated with tailings are reduced, and that remaining risks are effectively managed. However, we must recognize that conformance with standards can have a down-side – the proverbial two-edged sword. Having standards is vital but there is a risk that implementing standards becomes a “box checking” exercise, with ongoing conformance leading to complacency. We must not allow ourselves to fall into the trap of believing that, just because we are complying with applicable standards and laws, we are therefore doing our best, and that “it can’t happen to us.” In addition, if conformance becomes the goal and the standard does not have mechanisms to drive continual improvement, then once the standard is met, there may be no incentive to improve. The point of complying with standards is not to pass the test. The point is to manage tailings responsibly, prevent catastrophic failures, and minimize harm. The point is to do better, because we must do better. To do that, we need to strive not for conformance, but for excellence in tailings management, driven by continual improvement and a quest to do better.

Feb 1, 2025

By DING TANG, JINGHE CHEN, Shuiping Zhong, CHEN KUANG

The Zijinshan gold-copper mine, in spite of the low-grade nature of the ore, has become one of the largest production-scale and most profitable non-ferrous metal mines in China. The successful application of hydrometallurgy as well as proper engineering design are the key factors for large-scale development of the Zijinshan gold-copper mine. In this contribution, the practical experience acquired in the development of the Zijinshan gold and copper mines is summarized. This covers most aspects of the production process including mining, beneficiation, ore stacking, heap (bio)leaching, carbon-in-leach, solvent extraction, electrowinning, wastewater and tailing treatments. The authors believe that this practical experience will not only help to promote the development of hydrometallurgy, but can also serve as a model for other gold and/or copper plants around the world.

Jun 3, 2020

By C. Fuellenbach, J. Brune

"INTRODUCTION Mining activities must be safe and profitable. These two requirements influence each other. The purchase and implementation of safety improvements costs money. Injuries and illnesses at mines stop or delay production and may result in additional costs or a loss of profit. Other effects of injuries and illnesses include the negative influence on employee morale, corporate reputation and conflicts with contract partners. Based on this researchers asked the question: are mines with lower rates of injuries and illnesses more profitable than mines with a higher frequencies? One aspect of this research is the evaluation of the safety situation and the measurement of benefits of safety improvements in the German mining industry. In the following paper, this part of the research will be examined. The main aim is the evaluation of injury rates in different German mining sectors and regions in Germany. SELECTION OF GERMAN MINING OPERATIONS The research team decided to focus the study on the salt and potash and the aggregate and industrial minerals mining industries in Germany. These two mining industries are different in the number and size of operators, structure of the industry, pricing and markets. The selection of two different industries adds to the clarity of the evaluation. Salt and potash mining industry The German salt and potash industry is primarily located central Germany. All salt and potash mines in Germany are underground operations. In 2015, the German potash industry employed 8,100 employees and generated a total revenue of 2 billion Euros. German potash reserves include magnesium compounds like kieserite (MgSO4·H2O), in addition to sylvite (KCl) and carnallite (KMgCl3·6(H2O)). The German salt industry employed 2,300 people in 2015 and generated revenue of 800 million Euros (Krueger, 2015) There are seven mining companies with salt and potash operations: esco-european salt company GmbH & Co. KG, K + S Kali GmbH, Saline Luisenhall GmbH, GSES Glückauf Sondershausen Entwicklungs- und Sicherungs-gesellschaft GmbH, Südwestdeutsche Salzwerke AG, Wacker Chemie AG and Südsalz GmbH. In this way, esco – european salt company GmbH & Co. KG is an affiliated company. Esco was founded as a joint venture of K + S and Solvay in 2002, since 2004 K + S is the sole holder (esco - european salt company GmbH & Co. KG, 2016). Likewise, the Südwestdeutsche Salzwerke AG has a controlling interest in Südsalz GmbH (Südsalz GmbH, 2016). Aggregate and industrial minerals mining industry The aggregate mining industry in Germany is comprised of many small mining operations and relevant companies. According to the German Department of Economics (BMWi, 2015), the following industrial materials are classified as aggregates: fluorite, barite, kaolin, quartz and quartz sand, quartzite, silica, loamy and foundry sand, pegmatite sand, shale, clay, bentonite, schistose, limestone and dolomite, gypsum and anhydrite, basaltic lava and lava sand, gravel and split, pebble and silicic sand and peat."

Jan 1, 2017

By Milan Yekich, Emanuele Cauda, Justin Patts, Cody Wolfe

A worker’s personal exposure to respirable dust in occupational environments has traditionally been monitored using established methodologies which entail the collection of an 8-hour representative sample that is sent away for laboratory analysis. While these methods are very accurate, they only provide information on the average exposure during a specific time period, generally a worker’s shift. The availability of relatively inexpensive aerosol sensors can allow researchers and practitioners to generate real-time data with unprecedented spatial and temporal granularity. Low-cost dust monitors (LCDM) were developed and marketed for air pollution monitoring and are mostly being used to help communities understand their local and even hyper-local air quality. Most of these integrated sensing packages cost less than $300 per unit, in contrast to wearable or area dust monitors specifically built for mining applications which have been around for decades but still average around $5,000 each. At the National Institute for Occupational Safety and Health (NIOSH), we are leveraging the power of high-volume data collection from networks of LCDM to establish baseline respirable hazard levels and to monitor for changes on a seasonal basis as well as following any application of control technologies. We have seen the effective use and advantages of monitoring live data before, during, and after events like shift changes, operational changes, ventilation upgrades, adverse weather events, and machine maintenance. However, many factors have prevented a systematic adoption of LCDMs for exposure monitoring: concern for their analytical performance, the complexity of use, and lack of understanding of their value are some factors. This contribution outlines a one-year case study at a mine in Wisconsin USA, covering the installation, maintenance, data visualizations, and collaboration between NIOSH researchers and the industrial hygiene professionals at the mine.

Feb 1, 2024

By F. Varley, J. Whyatt

A variety of dynamic failure cases with regional impact were described at a bump symposium held in 1958. These types of events, while rare, are of particular interest because their ability to impact a large area has disaster potential. These cases can be grouped into two broad classes of events by mechanism. These are (1) a slip along steeply dipping faults and (2) the fracturing of strong strata above or below the coal seam. Both failure modes produce dynamic or “shock” loads on the perimeter (roof, rib and floor) of mine openings. Special consideration should be given to these failure modes in the planning of deep coal mines, since their occurrence is not within the professional experience of many contemporary workers. In addition, their potential is not evaluated by many of the analysis tools commonly used to evaluate hazards in coal mine plans.

Jan 1, 2009

By J. R. Patts, A. B. Cecala

"After industrial sand has been mined and processed, the finished product is typically loaded into small bags of 45 kg (100 lb) or less, large bulk bags of 454 to 1,361 kg (1,000 to 3,000 lb), or vehicles such as trucks or trains for transport to end users. As the sand is being transferred and loaded, dust can be released into the work environment, potentially exposing workers to respirable crystalline silica. A number of control technologies have been developed and utilized in an effort to reduce dust liberation during loading operations. For bulk loading into trucks or trains, the U.S. National Institute for Occupational Safety and Health (NIOSH) evaluated one of these technologies, the Dust Suppression Hopper (DSH), at two industrial sand processing plants. Results from these case studies show that the DSH reduced airborne respirable dust levels by 39 to 88 percent, depending upon the product size being loaded.IntroductionInhalation of respirable crystalline silica dust can lead to the development of silicosis, a disabling and potentially fatal lung disease. Once contracted, there is no cure for silicosis, so the goal is to prevent the development of the disease by limiting exposure to respirable dust containing crystalline silica at or below the exposure limit of 50 µg/ m3 recommended by the U.S. National Institute for Occupational Safety and Health (NIOSH, 2002). At industrial silica sand operations, the product contains high levels of crystalline silica, so effective control technologies are needed to minimize the respirable dust exposure of workers.NIOSH, in partnership with the Industrial Minerals Association–North America, published a dust control handbook (NIOSH, 2012) focused upon control technologies for industrial- mineral mining and processing operations. One chapter in this handbook discussed technologies for controlling dust liberated during bulk loading, including telescoping loading spouts, dust collection systems for loading spouts, enclosures for load-out areas and a newer technology known as Dust Suppression Hopper (DSH)."

Jan 9, 2018