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By J. F. Burr, D. Snyder, W. Calder

"INTRODUCTION “Explosion protection” refers to techniques used to minimize the potential for electrical and electronic equipment to create an ignition while operating in a hazardous location (HAZLOC). In particular, U.S. coal mines are required to use equipment in certain areas of the mine that has been approved by the Mine Safety and Health Administration (MSHA) for use in a methane and coal dust environment to limit the risk of the equipment creating an ignition-capable spark or a thermal energy ignition. In general, MSHA’s regulations for explosion protection recognize two techniques: the use of explosion-proof enclosures (XP boxes) and 2-fault intrinsic safety for electrical and electronic equipment. For 2-fault intrinsically safe (IS) equipment, the U.S. mining industry requirements are unique in that the equipment is certified by MSHA. The criteria MSHA uses to evaluate equipment for intrinsic safety, as required by Title 30 of the Code of Federal Regulations (30 CFR) [30 CFR, Sections18.20(b), 18.68(a)(1), 19.1(b), 20.1(c)(2), 22.6, 23.6, and 27.20(a)], is published in a document referred to as ACRI2001 (1). Outside of U.S. underground mining, many industries and countries accept equipment that is designed to a consensus-based international standard (ANSI/ISA 60079-11 is the U.S. version). The purpose of this study is to provide an overall assessment of the ANSI/ISA 60079-11 standard on 2-fault intrinsic safety and the MSHA ACRI2001 acceptance criteria, and determine if the ANSI/ISA document can be an alternative to ACRI2001 while maintaining an equivalent or better level of safety for miners. There are many drivers for this study. First, immediately after the 2006 MINER Act (2) was passed, there was a perception in the industry that the unique MSHA requirements were contributing to delays or restricting the availability of equipment to meet the requirements of the Act. Additionally, the MINER Act required that mine operators submit an accident response plan for MSHA approval, to be reviewed every six months. MSHA is required to determine if these plans reflect the most recent credible scientific research and make use of currently commercially available technology. There is a concern, as expressed in a recent National Academy of Science (NAS) study (3), that the unique requirements for U.S. mining may be limiting the technologies available to coal miners and technology options for mine operators. Accordingly, the study recommended that the National Institute for Occupational Safety and Health (NIOSH) and MSHA re-examine their technology approval and certification processes to ensure they are not deterring innovation, and explore opportunities to cooperate with other international approval organizations to harmonize U.S. and international standards without compromising safety. Lastly, the National Technology Transfer Act (NTTA) and the accompanying Office of Management and Budget’s OMB-119 circular mandate the use of consensus-based standards by federal agencies. However, for U.S. mining operations, MSHA cannot accept such standards unless a determination is made that such standards provide an equivalent level of protection for the miner, per the requirements of the 1977 Mine Act, the 2006 MINER Act, and 30 CFR Part 18 regulations."

Jan 1, 2017

By S. Renslow, G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Clays are known to contribute to a wide range of mineral processing challenges. These challenges can haunt a plant from the pit, through the beneficiation plant and even to the tailings pond and process water. Each step that the clay is present potentially experiences significant and costly impacts to the process efficiencies. The effect of clay minerals on the performance of phosphate flotation was investigated. The investigation led to an understanding of the movement of clay through the beneficiation plant, the impact on reagent usage, and the overall flotation performance. INTRODUCTION With the decline in mineral feed grades, mineral processing will continue to face challenges. One significant challenge would be obtaining high recoveries of industry specified quality mineral concentrates with lower quality raw minerals. Other challenges may be the handling of the excess tails and process water being produced to maintain a mill’s production volumes. For example, increased levels of clay have been, and will continue to be, a topic of concern for many mines. Some of these concerns include environmental regulations associated with water storage and discharge, as well as beneficiation. Gonglun Chen reported that clays produced in the phosphate industry are generally colloidal and fine (90% < 45 µm) (Chen, 2006). As such, these clays can take 20-30 years to settle, in the absence of polymeric assistance. The settling of these clays is essential as an accidental discharge can lead to substantial impacts to the wildlife and ecosystem. The Environmental Protection Agency (EPA) has referenced cases where the discharge of water can result in fines in the tens of millions of dollars, and at times causing the processing plants shut down, depending on the volume and quality of this discharged water (EPA, 1997). The turbidity discharge criteria will vary from state to state. Florida’s Department of Environmental Protection has listed a turbidity maximum of 29 NTUs, or 60 mg/L total suspended solids, above the natural background condition (Florida Department of Environmental Protection, 2016). A lot of the literature has been focused on the impact of high levels of clay (>10%) on mineral processing. Farrokhpay has reported the significant impact of clay minerals on froth stability in copper flotation (Farrokhpay, 2012). He reported that clays can form a hydrophobic slime coating on the surface of bubbles, which can yield an increase in froth stability. Clay concentrations as low as 5% can have significant impacts on the rheological properties or slurry viscosities. Increased slurry viscosities can lead to either elevated pumping/processing energies being required, decrease in flotation efficiencies due to a decrease in bubble mobility through the pulp, or decreased throughput to manage these viscosities (Tu, 2005; Farrokhpay, 2013; Burdukova, 2014)."

Jan 1, 2017

By M. Gobla

"Since 1994 the Bureau of Reclamation has used risk analysis to evaluate dams. Risk considers both the likelihood of failure and the expected consequences should failure occur. Risk analysis relies on the detailed formulation and critical analysis of all possible potential failure modes. Potential failure modes are formulated by describing the sequence of events that must occur to result in failure, where failure is defined as the uncontrolled release of the impounded reservoir. Failure occurs in response to loadings such as water seepage through a dam (static forces), shaking from an earthquake (dynamic forces), sudden flood inflows (hydrologic forces), or accidental overfilling (operational errors). Reclamation has applied risk analysis methods to inactive and abandoned mines to evaluate tailings dams and flooded underground mines. Case histories of potential failure mode analysis as applied to mine impounded water illustrates what critical technical information is needed to determine if failure is likely, what the consequences of failure are likely to be, and what are the highest risks that should be addressed first. INTRODUCTION Impounded water, and high water content wastes, at mining and industrial processing sites are potential threats to public safety and the environment. Recent failures such as the TVA Kingston flyash impoundment failure in Tennessee in 2008 (5.4 million yd3 released), the Mt Poly Tailings Dam failure in British Columbia in 2014 (5.8 million yd3 released), and the Smarco Fundao Tailings Dam failure in Brazil in 2015 (78 million yd3 released) has renewed attention to this issue. Potential risks from impounded water at mining and industrial sites originates not only from tailing dams, but also from water in process ponds and conveyance pipelines, sediment retention dams, water retention dams, mine pit lakes, and flooded underground mine workings. Conventional water retaining dams also have a record of failure. Notable examples of failure include Vajont Dam in Italy in 1963 (2,600 lives lost), Banqiao and Shimantan Dams in China in 1975 (171,000 lives lost), and Machhu-II Dam in India (10,000 lives lost). After the 1976 Teton Dam failure in Idaho, the Bureau of Reclamation (BOR) established a Dam Safety Program. By 1984 the agency developed and began using risk analysis methods. Reclamation operates and maintains an inventory of hundreds of aging dams which were designed and constructed over a period of one hundred years. Many of these facilities were constructed using engineering design and construction methods which would not be considered good practice according to present day standards. Diligent observational monitoring, detailed site investigations, and the application of risk evaluation to the BOR dam inventory has identified many deficiencies resulting in significant demands on available funding for remediation efforts. The application of risk analysis has allowed the agency to rank sites by risk. By giving priority of remedial efforts to high risk sites, significant improvements to dam safety have been achieved. BOR has also applied risk analysis to evaluate and reclaim inactive and abandoned mining and industrial sites. The application of risk analysis methods in the mining industry is not new, the methodology was transferred to the mining industry more than 15 years ago as discussed in ICOLD Bulleting 121 (ICOLD, 2001), yet failures persist. This paper is meant to convey the lessons learned from BOR’s use of risk analyses in its work on mine sites."

Jan 1, 2017

By Songlin Ye, Frank Su

"Recycling valuable metals from waste streams has become increasingly important to the mining and smelting industry in China due to resource depletion and environmental concerns. Predicated on multiple large scale metal recovery operations designed by BQE Water at active mines in the Jiangxi Province of China, this paper presents a case study demonstrating recovery of zinc and copper from the waste stream at a major gold smelter in the Shandong Province of China. One of the issues facing the smelter is the lack of a cost-effective and robust process to recover zinc from the acidic process waste stream. As such, significant amounts of zinc-containing wastewater are neutralized with lime, resulting in not only the loss of zinc metal but also the generation of large volumes of sludge. In the case study, a sulphide precipitation process is chosen to selectively recover zinc and copper from the wastewater, in the form of commercial grade metal concentrates that can be sold as regular concentrates at the going market price. In the current project phase, over 2,500 tonnes of zinc metal and 40 tonnes of copper metal can be recovered on an annual basis. This not only generates revenue to offset waste treatment costs, but also eliminates significant amounts of sludge that would otherwise require storing and further disposal if the metals are not recovered.Introduction / Background With resource depletion becoming a global concern and environmental regulations becoming increasingly strict, companies in the mining and smelting industry are actively seeking technologies to maximize resource recovery and provide concurrent minimization of waste residue production from operational activities. Mining and smelting companies have typically used lime neutralization as the primary method to reduce metal concentrations from mine waters prior to reuse or discharge to the environment. However, this process creates large volumes of metal laden sludge with long-term liabilities in the form of ongoing storage and management (Zinck et al 1997). Recovering metals of value from mine water not only reduces sludge volumes and the costs of associated liabilities, it produces a commercial grade metal concentrate that can be sold to generate revenues to offset treatment costs. ChemSulphide® is a sulphide precipitation process developed by BQE Water that has been successfully applied at mine sites in the Jiangxi Province of China to remove and recover copper from acid mine drainage. The success of these copper recovery water treatment plants demonstrates both the economic and environmental benefits of recovering residual metals from mine water and provides reference for the copper and zinc recovery project at a gold smelter in the Shandong Province that is the subject of this case study."

Jan 1, 2017

By W. V. Liu, D. Omane, H. Yu, Y. Pourrahimian

"A large-scale wildfire had broken out at Fort McMurray in Alberta, Canada during May 2016. Many oil sands mining activities were affected due to the wildfire and the associated ash emissions. In particular, ash emission generated from the fire outbreak is a huge problem during the post-fire cleanup. These emissions pose a severe health hazard to workers, environment, and global climate. The ashes emitted into the atmosphere are caused by either human activities or climate conditions. The objective of this research is to assess the effect of three different ash dust suppressants, namely water, #1 surfactants, and #2 polymers at various volumetric concentrations on ashes samples to prevent propagation of fine solid emissions into the atmosphere. It is found that both #1 surfactants solution and #2 polymers solution are effective in retaining fugitive ash dust generated from the ashes. Volumetric concentration efficiency of 0.05% of #1 surfactant and 5% of #2 polymers in 500 ml of water have been proven to provide ash dust retention efficiency greater than 99% after the spraying of these suppressants. It is also found that both #1 surfactants solution and #2 polymers solution maintain an ash dust retention efficiency higher than that of the use of only water. This confirms the merit of using chemical dust suppressants on fugitive ash dust for a longer period, which is proven by the 72-hour data from this experiment. This study gives a general view of how effective chemical suppressants on fugitive ash emissions work. INTRODUCTION On May 1st, 2016, a large-scale wildfire gutted Fort McMurray, Alberta, Canada. Many oil sands mining activities were affected due to the wildfire and the associated ash emission. Due to the wildfire, some of the biggest oil sands companies in Fort McMurray such as Royal Dutch Shell and Suncor Energy shut down their oil production, at 255,000 and 350,000 barrels per day respectively [1]. Syncrude Canada Ltd scaled down its normal production capacity level of 350,000 barrels per day [1]. This generated an estimated loss of about 1.1 million barrels of oil production per day, constituting a 30% reduction in the Canadian daily oil production, crippling the economy [2]. This loss in production by the companies translated into 0.33 % of the Alberta GDP in 2016 constituting a loss of $985 million and 0.06 % of the entire Canadian economy [3]. In 2017, it is estimated that the rebuilding and reclamation of the affected areas in Fort McMurray will add $ 1.3 billion in GDP to Alberta’s economy [3]. A population of over 90,000 people was evacuated from the location and its surroundings for health and safety reasons [4]. The fire destroyed about 2,400 structures and over 500,000 hectares of forest vegetation in Fort McMurray, leaving an estimated 232,000 tonne of post-fire ashes [5,6]."

Jan 1, 2017

By L. Yuan, J. H. Rowland III

"In 1995 and 2003, the Mine Safety Health Administration (MSHA) conducted surveys to determine the number of atmospheric monitoring systems (AMS) being used in underground coal mines in the United States. The survey reports showed data for the different AMS manufacturers, the different types of equipment monitored, and the different type of gas sensors and their locations. Since the last survey in 2003, MSHA has changed the regulation requirements for early fire detection along the belt haulage entries. As of December 31, 2009, point-type heat sensors were prohibited for use for an early fire detection system; instead carbon monoxide (CO) sensors are now required. This report will examine the number of AMS currently used in underground mines in the United States to see if there is a change in their use. The locations and parameters monitored by AMS are also discussed. INTRODUCTION The last survey conducted by the Mine Safety and Health Administration (MSHA) on atmospheric monitoring systems (AMS) used in underground coal mines in the United States (US) was in 2003 [1]. The survey report states that since 1995 there had been a steady increase in the use of AMS in underground coal mines as the technology of CO sensors was improved by manufacturers. AMS had become more reliable and some CO sensors could be purchased with the capability to discriminate between the CO produced from a fire versus CO produced from diesel equipment. This increase in reliability had reduced the number of false alarms and the response time. The faster response time to a developing fire allowed for the miners to take the necessary action to put out the fire or exit the mine. It should also be noted that at the time of last MSHA survey, some mines still used point-type heat sensors to detect the presence of a fire on conveyor belts. This detection method works by measuring the temperature of the air around the sensor. As a fire starts to develop, smoke and hot gases are produced from the combustion process, and the air is heated up. Once the air and gases reach a designated temperature detected by the point-type heat sensor, a fire alarm signal is generated. Studies have shown that the response times for detecting the presence of a fire using CO sensors are much shorter than using point-type heat sensors [2]. Finally, since the last MSHA survey, regulations have changed on the type of automatic fire detection systems permitted to be used in conveyor belt entries. As of December 31, 2009, point-type heat sensors are not permitted to be used for fire detection in underground coal mines in the US; instead CO sensors are required as a replacement (30 CFR 75.1103-4). This study will examine how the changing of the above regulations has impacted the use of CO sensors in underground coal mines in the US compared to their use based on the last MSHA survey. Importantly, in the previous MSHA survey, the data was recorded for producing and non-producing coal mines. In this study, only the data from the producing coal mines was recorded. Data was collected from a total of 235 coal mines for this study with the help of the MSHA district offices."

Jan 1, 2017

By Zefang ChenLi, Laijun Ma, Lei Mao, Fang Lian

"In our work, the preparation technique of high pure manganese sulfate directly from low-grade rhodochrosite ore (MnCO3) was studied and improved intensively, including the effective leaching process and the short purifying process. Based on the same ion effect, the repeated leaching of rhodochrosite with sulfuric acid is proposed to improve the solubility of Mn2+ and inhibit the dissolution of the impurities Ca2+ and Mg2+. Moreover, the repeated leaching process could make full use of rhodochrosite and lower the dosage of sulfuric acidas raw material. With the aid of theoretical calculation, Ba(OH)2 was chose to adjust the pH value of manganese sulfate solution, and BaF2 to remove Ca2+ and Mg2+completely in the process of purifying. The results demonstrate that the extraction ratio and the recovery ratio of manganese reached 94.3% and 92.7%, respectively, which shows the prospect of industrial application. In manganese sulfate production, the heavy metal impurities have been decreased to less than 1ppm. Moreover, the content of calcium, magnesium and sodium has been decreased to less than 20ppm, which meets the standards of high pure reagent for energy and electronic materials. Our study enlightens an approach to the sustainable application of low-grade rhodochrosite.Introduction Low-grade manganese carbonate ores (=14%) becomes gradually the main resources for exploitation and applications in China according to national mineral resources survey (Tan et al 2004 and Singh et al 2017). Therefore, the electrolytic deposition technique of rhodochrosite faces great challenges including low electrolysis efficiency, high-resource input and high-pollution discharge (Fu et al 2010, Michelis et al 2009, Zhang et al 2013). Recently, more and more amount of manganese series with high or super high purity such as MnSO4, MnO2, Mn3O4 and MnO is demanded with the development of energy and electronic materials. Due to low-grade ores containing multiple elements such as iron, silicon, calcium and magnesium, conventional preparation of manganese sulphate with high purity from electrolytic product is characterized by long production-cycle and high-energy consumption (Subrat et al 2011, Mpho et al 2013). By contrast, hydrometallurgical method combined with thermal decomposition, hydrothermal synthesis and sol-gel processes has been widely studied because of its high efficiency, low consumption and low cost (Chen et al 2008). But the key problem in direct preparation of manganese series form low-grade rhodochrosite is to remove completely the multiple impurities such as iron, silicon, calcium and magnesium (Liu et al 2014). So it is urgent to develop a sustainable alternative approach with character of short process, high efficiency and environmental friendly."

Jan 1, 2017

By A. Pezzuto

"Pipes are used on mine sites in a variety of applications including transport of slurry, conveying clean and processing water, and in mine dewatering. Mine waters and slurries can cause pipe wear and failures via several mechanisms (or combinations thereof) such as abrasion, scaling, and corrosion. Polyethylene (PE) pipe materials have grown in popularity over the past several decades due to their chemical and mechanical properties (e.g., inertness, flexibility, relatively low density) and low cost. While PE is generally resistant to corrosion, it is subject to abrasion. To combat this, a novel, rubber-like liner is in development. In addition to comprehensive abrasion testing, however, the liner must be evaluated to see how it performs under other conditions. Here, a brief field study is described that tested PE pipes with the new liner against traditional PE pipes to specifically assess mineral scale buildup. The study was conducted in the Reiche Zeche study mine in Freiberg, Germany in six different locations with varying water qualities and flow conditions. INTRODUCTION Water and slurry conveyance are major operations on and around mine and mill sites, from mine dewatering, to tailings transport, to water treatment processes. Conveyance systems in such applications can include great lengths of pipe materials along with pumps and monitoring instruments, and thus represent significant capital investments. Due to the variability of the physical and chemical properties of water and slurries, pipe materials are subject to a wide range of conditions. These can cause pipe wear and eventually failure leading to serious economic, environmental and social, consequences. While pressure-induced pipe failures (e.g., ruptures or ""bursts”) can be immediate, most failure mechanisms involve gradual processes. Scaling and sedimentation can present major problems for pipe systems conveying highly mineralized waters. Sedimentation generally refers to the deposition of suspended solids, such as sand, clay, silt, or organic matter onto pipe surfaces. This phenomenon can occur due to a decrease in water velocity or particle collisions with the pipe wall. Scaling, on the other hand, commonly refers to the deposition of precipitated mineral salts (including oxides and hydroxides) onto pipe surfaces. Mine waters often have extremely high ion concentrations (i.e., high dissolved solids content) due to their interaction with enormous surface areas of minerals, which are exposed during mining and processing operations (Brown and Barley, 2002). As these waters are transported, slight changes in temperature, pressure or chemistry (e.g., pH or ORP) can cause instability with respect to ion solubility such that salt precipitation begins to occur. “Seed” crystals can rapidly grow and attach to pipes, either due to local surface phenomenon near the pipe wall (e.g., which can promote coagulation) or sedimentation of the precipitated solid. Whether due to suspended or precipitated solids, as the solids begin to stick to pipe walls, “aging” or hardening processes can commence; and the build-up of scale can become self-perpetuating as the scale itself provides an attractive “nucleus” for further attachment of particles or crystal growth (Muryanto et al., 2014). Over time, scale-buildup reduces the effective pipe diameter, which can ultimately result in decreased flow velocity, clogging and, in some instances, bursting (Dirany et al., 2016)."

Jan 1, 2017

By A. Navarra, F. Mucciardi, H. Marambio, R. Parra, F. Oyarzún

"Discrete event simulation (DES) is an appropriate framework for the plant-wide analysis of copper smelters. These smelters apply a common set of chemical reactions: copper-iron sulfides are blasted with oxygen-enriched air, sending the iron into a slag phase and the sulfur into the offgas. Moreover, conventional copper smelters exhibit similar operational dynamics: a smelting furnace operates continually, feeding into an alternating set of converters that produce batches of blister copper. The thermochemical and operational commonalities of copper smelters are integrated within the DES framework. This serves as a common basis to begin evaluating the system dynamics of individual smelters. For complex problems, the simulation framework should be developed in phases, incorporating feedback from different personnel who have complementary perspectives. Sample computations are provided in this paper based on the Hernán Videla Lira smelter, whose production is constrained by meteorological conditions. IntroductionWorld copper production is approximately 18.5 million t/y (Brininstool, 2015), worth $80 billion a year. Out of this total, 75 percent comes from the pyrometallurgical processing of sulfide minerals (Fig. 1), which occurs in copper smelters. The remaining 25 percent is from the hydrometallurgical treatment of oxides and complex ores (Rotuska and Chmielewski, 2008), which uses solvent extraction and electrowinning.The current paper describes the pyrometallurgical processing, recognizing that the underlying thermodynamics and kinetics are well known (Degterov and Pelton, 1999), with the notable exception of minor element transport, such as arsenic (As), antimony (Sb), bismuth (Bi), silver (Ag), gold (Au). The latter is an ongoing area of research, as smelters are faced with increasingly complex ores (Devia, Wilkomirsky and Parra, 2012; Swinbourne and Kho, 2012). This paper focuses on the system dynamics of copper smelter operations, which has received considerably less attention than the chemical thermodynamics and kinetics.Smelter engineers and managers may contribute to the sustainability of their plant by improving their understanding of operational system dynamics. Indeed, we have prompted smelter improvement projects (Navarra, 2016; Navarra et al., 2016; Navarra and Mendoza, 2013) simply by adapting methodologies that are commonly used in other sectors. These previous works incorporate principles from computer-integrated manufacturing (Groover, 2000) and theory of constraints (Dettmer, 2007), featuring the use of discrete event simulation (DES)."

Jan 1, 2017

By Yanchuan Li, Haifei Yao, Haiyan Wang

"Dust pollution is very serious in coal mining process, which is a great threat to the underground staff health and equipment and facilities safety. Coal seam water injection in mining process is an effective way to reduce coal mine dust concentration at the source. However, the effectiveness of water injection is limited in high-pressure and low-porosity coal seam. To improve the moisture content of coal seam, expand the wetting range and enhance the effect of dust reduction by water injection, the injectability and influencing factors of coal water injection are analyzed by numerical simulation method, and the sealing technology under high-pressure condition is studied. Then, according to the practical conditions of Tangkou coal mine, the parameters and process system of process system are designed, the effect of high-pressure water injection in coal seam was determined by testing water injection quantity, water increment and dust concentration. It is showed that the dust-removal rate of the high dust concentration operation such as falling coal and moving frame is 63.49% and 59.72%, the maximum dust-removal rate of multi-processes is 53%, which achieve a high level of application. The research results in this paper is of important theoretical and practical value to improve the water injection effect of high-pressure and low-porosity coal seam and improve the efficiency of dust removal in coal mining process.Introduction With the increasing of the depth and mechanization of coal mining, coal dust, the impact of ground pressure, ground temperature and other natural disasters continue to upgrade the harm degree (Wang 2011, Wu et al 2012), disaster incidents occur frequently, which seriouslythreaten the safe and efficient mining and the physical and mental health of underground staff. Coal seam water injection can effectively reduce the coal dust when coal crushing, prevent the impact of mine pressure, coal and gas outburst disasters, by increasing the thermal conductivity of coal, reduce coal temperature, and prevent spontaneous combustion of coal. In addition, coal seam water can soften the hard coal, so that speed up the recovery rate, improve coal production and efficiency (Wu et al 2008, Nie et al 2007). However, the coal seam in many mining area is with high-pressure and low-porosity feature, Coal joint cracks are not developed and relatively hard, water injection is difficult in these coal seams, then the desired disaster prevention effect cannot be achieved (Jin et al 2001, Zhao et al 2000). In this paper, the numerical simulation and field test methods are used to design the high-pressure and low-porosity coal seam water injection technology, so as to solve the difficult problem of coal dust control in high-pressure and low-porosity in deep well mining process."

Jan 1, 2017

By Song Jiang, Xianzhi Tan, Minjie Lian

"The ground water heat pump system lades underground hot water which can be heated or cooled by heat exchanger in water source heat pump air conditioner. This system replaces the model of heating of air-conditioning by refrigerator and boiler. In this paper, the formation conditions of hot water energy in Shan Dong are analyzed in order to achieve the purpose of energy conservation and emissions reduction by taking full advantage of water resources such as water pouring and return water of beatification during the productive process of underground metal mine. In order to analyze the issue better, the paper points out some ways and methods for geothermal water often used in underground metal mine. This paper also presents the advantages of the technology of water source heat pump that is applied into underground metal mine. Here is a case study of comprehensive utilization of water source in a certain underground metal mine in Ji Ning. This mine, according to its own actual situation, designs heat pump heat exchange system which is used for indoor heating of buildings and bath for staff. It turns out that the system can save 23% water per year, cut down 3.303 million KW electric energy, and reduce 4160t emission of carbon dioxide. It is concluded that the technology of water source heat pump has broad application prospects in underground metal mine. Therefore, the results show that it is an ideal way to change the present structure of cooling and heating source in metal mine.Introduction In recent years, overuse of fossil fuels has posed a grave threat onto the environment, which makes renewable energy a more important status in energy structure. Development and utilization of renewable energy has become an important direction. Water source heat pump technology is to use solar energy stored in water as cold/heat source to convert energy. Currently, this technology has been widely used in some advanced countries. However, due to facers of implementation technology and component costs, there is still a gap in water source heat pump technology between China and these advanced countries. According to (Blum et al 2011) that after in-depth study, water source heat pump technology has developed rapidly in China recently, and the gap is gradually reduced. Groundwater source heat pump system as a kind of high efficiency, energy-saving and environmentally friendly technology in recent years, more and more get the people's attention. At the same time, its practical application has also been rapid development. Based on (Ni et al 2015) that According to the relevant departments of the prediction, the technology will become the 21st century the most efficient heating and cooling technology."

Jan 1, 2017

By M. Z. Emad, M. U. Khan

"Coal mines opting for longwall mining or its variations rely on the main and tail gates for production. Stability of these entries or crosscuts is crucial in coal mining operations. Roof or strata failure can be fatal, may lead to property loss and delay in production. Failure of the gates depends upon many factors including the mining method, panel dimensions, pillar width, mine depth, caving rate, dimensions of gates and roof strength properties. In Pakistan coal is mined through a variation of longwall mining method with almost no mechanization while using timber as a primary support. Timber support as chock is very useful in coal mines especially in overhanging face. Similarly gate entries and coal faces are supported by chock supports throughout their length. In this paper the stability of the longwall gate is assessed for a typical coal mine in Pakistan by using finite element code. Numerical modelling considerations for gate entries are discussed. A model parametric study is performed for key factors. The results showed that the existing mining practice is not suitable and there is a need to review the mining approach. INTRODUCTION Main and tail gate entries leading to longwall mining panel play a crucial role in production cycle. Failure of any of these may lead to loss of life, property and production delays. The stability of gate entries depends primarily on the nature of loading and stresses incurred. It is relatively easier to assess the ground response to production for common longwall mining panel. In thin-seam coal mines the gate entries are generally supported throughout their length by timber made chock supports. The tailgates receive huge deformations and stresses during the mining and backfilling cycle. The chock supports are required to take care of rock falls leading to blockage of entries causing production delays and loss of capital. A number of supports are available for supporting the gate entries (Hoek and Brown 1980; Brady and Brown 1985). The support system can be selected based on load-deformation characteristics including the yielding behavior, pre- and post-yielding behavior (Barczak, 2003). The principal of support selection is that the support characteristics must match the ground response in order to maintain the gate entries (Mucho, et al., 1999). It has been observed that thin-seam mining (<1 m) is very challenging and it is necessary to develop an understanding of ground mechanics before the selection of an efficient support system Dolinar (2003). The chock supports have been tested for load-deformation characteristics in the laboratory (Barczak 2003). But the ground and support interaction, response and loads must be assessed for individual site. This can be accomplished by in-situ testing and observations at few locations. The generated data is generally insufficient for complete understanding. Numerical models can combine the data generated in the laboratory and on-site to fulfill the requirements."

Jan 1, 2017

By Z. Scopa, E. Tarshizi, R. Setterlind, L. Frost, R. Livernois

"THE MINES OF THE FUTURE The mines of the future present a host of challenges, which may appear exciting or daunting depending on one’s perspective. Whether some sectors of the public recognize it or not, the demand for raw resources is not going away any time soon. In fact, it is rising as global population grows, urbanizes and attempts to steadily increase quality of life. Yes, at the same time that much of the highly developed world is calling for greener goods, reduced consumption, and cleaner production, in other areas there are cries for clean water and sanitation, consistent energy supply, access to health care and education, personal security, and support for basic human rights. The balancing act for sustainable development of our global society is indeed precarious, and the mining community is necessarily a key player. Fortunately, many industry members have accepted this role and the responsibility to provide leadership and a solid foundation for progress. Looking ahead, we need new generations of leaders, many of whom will be mine engineers, which are ready to tackle all sorts of complex problems. There are tremendous needs just for technological innovations. Increasingly tough deposits will require that we continue to expand scale toward “super” pits and “deep” underground mining fully develop unconventional recovery techniques like in-situ leaching and gasification or deep-sea extraction, and seriously consider off-earth endeavors. Such work will take entirely autonomous equipment; novel separations, processing and recycling methods; and systems that can withstand extreme physical conditions – just to name a few. It will also take a level of systems integration never-before seen in our field, complete with big data issues, sophisticated analytics and modeling efforts, and cyber-security challenges. Moreover, increasingly complex environmental problems will require creative solutions. Addressing issues like pollution control across multiple media, emerging contaminants, optimal management of wastes, selective mining, and shared use of resources between mine operations and surrounding communities and ecosystems are among top priorities. Really, a complete paradigm shift must occur, such that our focus is on overall improvement of environmental conditions, rather than minimization of impacts. A similar shift will be required in the social realm. How can we make miners safer and healthier on-site and off? How can we contribute to communities such that they are better off, now and long-term, for having a mine next door? How can we help transform artisanal mining practices to also contribute to sustainable development? How can our work be a factor in increasing economic and political stability? How can we improve the public understanding of raw resources and the need for mining enterprises?"

Jan 1, 2017

By Cong Zhang, Huaying Wang, Yixin Wei

"Water inrush is a serious geological accident in underground coal mines. This paper focuses on the method of the bow tie analysis based on fuzzy reliability to assess the risk of water inrush in coal mines. First, post failure probability and repair probability of initiating events are divided into 5 levels. Then triangular fuzzy numbers are adopted to quantify experts’ language and to acquire the reliability rate which close to the actual values by defuzzification and calculation. According to dynamic bow-tie analysis model, using the method of moments to fit the reliability time of events by Weibull distribution and offering the random sampling rule of failure and repair time for illustrating the feasibility of fuzzy reliability evaluation. To demonstrate the effectiveness of the proposed assessment approach, bow tie analysis model of water inrush in coal mines is taken as an example.Introduction Dynamic bow tie (DBT) analysis is composed of dynamic fault tree and dynamic event tree analysis, and considers the impact of the time factor upon risk assessment of a system. There are many algorithms applied to calculation of the probabilities of node accident and accident consequence of dynamic bow tie analysis: Hidden Markov Model, Bayesian Network (Khakzad et al 2013), Integral Algorithm (Amari et al 2003) and Monte Carlo Simulation (Kim et al 2016). In terms of simulated time and practicability, the Monte Carlo Simulation has an advantage over other methods. DBT requires mass data in quantitative analysis, including the failure rates and the repair rates of the basic events of the Fault Tree (FT) and the subsequent events of the Event Tree (ET) at different time points, i.e., the distribution of failure time and repair time. In practical analysis, it is hard to obtain a large amount of exact historical statistical data, which is a major problem of risk assessment. Due to the difficulty of obtaining the exact data and historical failure data of the basic events and the subsequent events, the FT and ET analysis is stuck with the study of minimal cut sets, minimal diameter sets, structural importance and qualitative analysis (Liu and Zhang 2010, Yan et al 2012, Wang et al 2009, Li and Wang 2011). This paper will use fuzzy numbers and the defuzzification method to transform the experts’ language into the failure rates and repair rates of basic events and subsequent events, solving the problem that it is difficult to obtain a large amount of historical statistical data, and will use the method of moment to conduct Weibull fitting of the reliability time to provide the random sampling criteria of event failure and repair time in Monte Carlo simulation."

Jan 1, 2017

By L. Wilfley, G. A. Calboreanu

"Wear resistant 25% Cr hard cast iron is a heterogeneous material containing 1,600 HV hard chromium carbides embedded into martensitic matrix. It is the most used cast alloy in wear operations of mining industry, chemical industry, fracking, etc. During the last decade the hard iron manufacturers increased wear resistance in the following ways: • Reduce / eliminate harmful retained austenite and chromium + carbon depleted areas especially within eutectic carbide cells. In Max5A the improved 25% Cr alloy brittle carbide eutectic cells are removed which increases toughness. • Delay delamination between chromium carbides and matrix particularly during sliding abrasion wear. Delamination commences at the weakest chromium carbide – matrix contact lines exposing chromium carbide to localized bending stresses which gradually chip carbides away. Once the chromium carbide base is removed accelerated wear degradation occurs. • Evenly randomize and avoid discontinuities in the chromium carbide network. When chromium carbides are perpendicularly positioned to the wear surface wear rate is minimized. On the contrary the highest wear rate takes place when 3D oriented chromium carbides are parallel with the wear surface. In this case chromium carbides cover top network discontinuities being just matrix supported which leads to rapid carbide cracking. The new hard iron discussed in this paper fulfils and exceeds the above requirements increasing the casting service life around 250% in various wear operations. Physical and mechanical properties of Max5A are compared with well manufactured Industry Standard 25% Cr hard iron. The paper presents practical accomplishments obtained in the USA, South America and India. INTRODUCTION The chemical composition of Max5A and Industry Standard 25% Cr are identical like specified by ASTM A532 Class III Type A requesting C = 2.0-3.3% and Cr = 23.0-30.0%. Manganese, silicon, nickel, molybdenum and copper contents are limited by maximum accepted quantities.[1] According to published data the eutectic chromium carbides chemical composition of 25% Cr hard iron is Cr = 54% and C = 8% which indicates strong depletion of chromium and carbon along chromium carbide - matrix interfaces. [2] The optimized Max5A microstructure has minimized retained austenite, is devoid of harmful carbide eutectic cells and has the most advantageous chromium carbide and secondary chromium carbide morphology. This favorable microstructure increases wear resistance, mechanical properties and corrosion resistance. The paper compares the Max5A microscopic features and mechanical – physical properties with similar properties of high quality Industry Standard 25% Cr."

Jan 1, 2017

By Bern Klein, Rafael Fernandes de Mesquita, Fatima Regina Ney Matos, Andre Xavier

"193 United Nations members are signatories of the 17 Sustainable Development Goals (SDGs). Even though it does not make it legally binding to the country members, the SDGs establishment incites national and managerial frameworks to achieve the SDGs. The mining industry inserts itself in this context by its global presence and frequent location within ecologically sensitive and less developed areas. This paper aims to consolidate the state of academic research on mining, sustainability and sustainable development, by organizing the results of previous studies within a systematic review on the SDGs set. To do so, the ISI Web of ScienceTM Core Collection database was chosen as a database of record, as it is one of the most widespread databases of academic journals. We have used all years available in the ISI database, from 1945 to 2016 (for complete years). The systematic review process comprised of five steps: (i) to search terms [(“sustainability” or “sustainable development”) and mining] on the database and to apply filters of criteria; (ii) organizing papers; (iii) metrics and relations between papers and authors; (iv) classification of the results through content analysis techniques; and (v) synthesis. The results were divided in two groups: the highly cited and the most recent papers, to include papers that have academic impact and those which show the newest contributions to the field. The results showed that, in spite of a growing amount of publications in the past years that relates to mining and sustainability, the main focus of these publications are still on the environmental dimensions of the UN goals. This suggests that more practical and academic work in the mining sector are required to fill in the blank spaces regarding the other set of goals that compose the SDGs framework.Introduction A total of 193 United Nations members are signatories of the 17 Sustainable Development Goals (SDGs). Even though it does not make it legally binding to the country members, the SDGs establishment incites national and managerial frameworks to achieve the SDGs. The mining industry inserts itself in this context by its global presence and frequent location within ecologically sensitive and less developed areas (Atlas 2016). The goals are important because they add common targets for different countries and easily establish discernible criteria for it (Costanza et al 2016). A forward-looking approach like the SDGs would be able to attach the sustainable development framework with profitable activities taken by the mining companies (Starke 2016). This paper aims to consolidate the state of academic research on mining, sustainability and sustainable development, by organizing the results of high impact previous studies and recent publications, within a systematic review, on the SDGs set. By doing so, the results can portray the actual concern and the lacks that the academic field had on this subject in comparison to the UN contemporary agenda."

Jan 1, 2017

By J. R. Schafler, J. L. Brinkman

"The US coal mining industry has suffered a recent decline in profits caused by a combination of decline in commodity demand and more restrictive government regulation, forcing coal mining companies to cease production in numerous mines. A 40% decrease in the total number of coal mines occurred from 1994 to 2000. The number of mines remained relatively constant until 2008 when a change of government sparked a series of new environmental regulations which have contributed to another 15% decrease from 2008 to 2016. In contrast, production has only decreased by 3%, increasing from 1994 to 2008, and then decreasing since 2008. However, this value is skewed by large increases in sub-bituminous coal production and decreases in other coal ranks. Several aspects assist in executive decisions on mine longevity and economic worth. Studies of open source mine data collected by mandated government surveys coupled with commodity history can be used to find relationships between mine closures and these elements, which include statistics on production tonnage, seam height, coal rank, etc. This paper looks at coal mining trends since 1994 by comparing mine, market, and regulation factors that may influence mine closure. INTRODUCTION The US coal mining industry is currently experiencing a decline in both demand and commodity price while facing implementation of more stringent air and water pollution regulations. Company profits have decreased significantly, forcing several major companies to declare bankruptcy. The industry was required to adapt to survive. Many of these companies have adjusted by abandoning mines; the last two decades have seen a drastic decrease in the number of mines. To discover the primary causes of this downturn, three major aspects must be studied: properties of abandoned mines, commodity history, and regulatory impact. TRENDS SINCE 1994 Each year, US coal mines are required to submit data on a wide variety of categories to the Mine Safety and Health Administration (MSHA) and the US Energy Information Administration (EIA). This data includes administrative records, production values, and information regarding the attributes of the mined material and the mine itself. Each year since 1996, EIA has released a report summarizing the data from two years prior. Additionally, MSHA maintains a database containing a collection of all the most current data. These resources are the primary sources for the following figures."

Jan 1, 2017

By T. Yue, Z. Gao, X. Tong, R. Liu

"Lead ions (lead nitrate) were introduced to modify the surface properties of scheelite, effectively and selectively improving the flotability of scheelite, with benzohydroxamic acid (BHA) serving as the collector. A series of experiments about the mode of addition and the ratio of lead ion to BHA were conducted and indicated Pb-BHA complexes were the active species responsible for the flotation. And two adsorption models of BHA on the surface of scheelite were established. For both the two adding methods, some kind of complexes formed by lead ions and BHA played a key role in the flotation process. Zeta potential, FTIR, and XPS studies indicated that the adsorption amount and intensity of BHA on the surface of scheetlie were larger by adding the reagents as a mixture. The mixed addition is conducive to form Pb-BHA complexes and improve the adsorption efficiency of BHA on the surface of scheelite, as well as the recovery of scheelite. INTRODUCTION Scheelite, as an important tungsten-bearing mineral, is nowadays utilized mainly by flotation (YIN and WANG, 2014; Sun et al., 2011; Gao et al., 2015; Gao et al., 2015). Flotation separation of scheelite from calcium minerals creates difficulties because of the existence of the same cation in the minerals and similar physico-chemical characteristics such as solubility, hardness, specific gravity, point of zero charge (PZC), etc. (Arnold and Warren, 1974; Deng et al., 2016; Deng et al., 2015; Ozcan and Bulutcu, 1993a; Yongxin and Changgen, 1983). The conventional collectors used in the flotation of scheelite ores are generally fatty acids or fatty acid derivatives (Bo et al., 2015; Oliveira and Sampaio, 1988; Shi et al., 2014; Sivamohan, 1988; Yongxin and Changgen, 1983). It is difficult to separate scheelite, especially from calcite, with these reagents because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface (Atademir et al., 1979; Changgen and Yongxin, 1983; Hiçyìlmaz et al., 1993; Hu et al., 2011). Therefore, it is almost impossible to separate them by fatty acid flotation without using any selective depressant. Although oleoyl sarcosine was used as a selective collector in the flotation of fluorite and siliceous scheelite ores (Ozcan and Bulutcu, 1993b; Ozcan et al., 1994), this selectivity is inadequate for a low-grade calcitic scheelite ore. Unfortunately, reagents such as organic colloids (dextrine, starch), quebracho, sodium phosphates, sodium silicate solutions containing polyvalent cations (hydrosols), etc. (Bo et al., 2015; Schubert et al., 1990; Shi et al., 2014; Yongxin and Changgen, 1983), used for calcite depression also depress scheelite to a large extent. Cationic collectors, such as amine and quarternary ammonium (Yang et al., 2015) and collector mixture (Gao et al., 2015) have been used to improve the scheelite flotation. However they have not been applied in industry due to the poor separation from silicate minerals."

Jan 1, 2017

By B. Berg, J. Stephenson, J. Mansanti, C. Nyikos

"Intrepid Potash, Inc.’s Carlsbad East facility has refined sylvite and produced muriate of potash (MOP) since 1965. In addition to MOP, Intrepid Potash began recovering the mineral langbeinite from a mixed ore reserve in 2005. In 2011 a new langbeinite recovery process for the coarse (+850 micron) size fraction was constructed to enhance the overall langbeinite recovery. Based on the limited mixed ore reserve and an abundance of langbeinite ore reserves the transition of the East plant to a langbeinite only facility was targeted for 2021. Due to a decreasing grade of the mixed ore reserve, declining sales pricing, and high sylvite operating costs a strategic decision was made to accelerate this transition into 2016. To enable a successful transition, a fines recovery system needed to be developed, constructed and implemented. This paper describes the advancement of langbeinite processing at Intrepid Potash and the planning, development and successful execution of the transition to a langbeinite only operation. BACKGROUND Langbeinite (K2SO4·2MgSO4) is a double salt containing potassium sulfate (K2SO4) and magnesium sulfate (MgSO4). It is used as fertilizer and in the industry is described as Sulfate of Potash Magnesia. It is attractive as a specialty fertilizer and in addition to containing a ready source of a primary nutrient potassium, it also provides two secondary essential nutrients, magnesium and sulfur. It is especially attractive for chloride sensitive crops. Langbeinite has a specific gravity of 2.8, a Mohs hardness of 4.2, and is brittle thus very friable. It is the hardest of the saline minerals, and despite its relative softness on the Mohs scale can be very abrasive in process environments and in field applications, probably due to its conchoidal cleavage. Its solubility at 240 g/l is less than the solubility of sylvite (KCl) or halite (NaCl) and due to even slower relative dissolution kinetics washing with cold water has been a common practice for upgrading langbeinite ores. The solubilization/crystallization relationship for langbeinite is different from the majority of other evaporite minerals in that once langbeinite is solubilized it does not form langbeinite again. Instead it gives up one mole of magnesium sulfate, takes on various waters of hydration and precipitates out as either schoenite (K2SO4·MgSO4·6H2O) or leonite (K2SO4·MgSO4·4H2O) depending on temperature. Due to its partial solubility and phase transitions at its surface when exposed to moisture, there is strong cohesion between wetted particles; the resulting stickiness of the upgraded products can create significant materials handling issues unless processed in slurry form or at relatively low moisture levels. Langbeinite has been produced commercially from two locations, the Kalush and Stebnik regions in the Cartpathian Mountains of former Poland and now the Ukraine and from the Permian Basin in New Mexico (Garrett, 1996; Smith 1949). Current production is from two operators in the U.S., Mosaic and Intrepid Potash."

Jan 1, 2017

By Ö. Y. Gulsoy, L. Ergün, I. B. Celik

"In this study, the studies to develop a flowsheet for a low grade chromite ore are presented. The existing concentrator had to be suspended due to the decreasing metal prices. The study commenced with mineralogy and liberation profile of the chromite. The valuable mineral is chromite and the major gangue mineral is forsterite together with small amount of brucite and calcite. Heavy liquid tests were performed on different size fractions without any acceptable success. The concentration tests were performed using teetered bed separator (TBS) +shaking table, spiral concentrator+TBS+shaking table for different grind size. Based on the test results, 100% finer than 0.4mm was found to be optimum for grind size. Comparison of alternative circuits showed that the performance of both alternatives would be similar. A flowsheet was designed and operated for as 25 tph trial circuit in the existing plant. The results showed that the performance of the plant predicted was very close to the actual plant data. The paper describes the methodology used, presents the experimental data and actual performance figures.INTRODUCTION Turkey is one of the largest chromite producers in the world. Since 1850, chromite mining found industrial applications and geographically spread along six different regions in Turkey. Although the reserves in these locations are not as rich as the big producers, they are regarded as very valuable due to Cr/Fe ratio in terms of chromite utilization standards (1, 2). In this period, significant portion of high grade (=35% Cr2O3), directly marketable ore deposits have already been produced. According to General Directorate of Mineral Research and Exploration (Turkey) data; 83% of the known chromite deposits of Turkey which makes 242 341 000 tons in total, is consisting from the deposits those have a Cr2O3 grade lower than 10%. Only 5% of the known deposits (13 087 000 tons) has a grade of directly saleable (2, 3). Gravity concentration methods are well-known processes for chromite beneficiation and there are plenty of plants in the world and Turkey using these methods. As different equipment combinations can be used for the same enrichment method, different methods can also be used in combination for plant designs (4). Beneficiation of low grade and problematic chromite ores may lead to use these method and equipment combinations (5, 6). Ore liberation, the grades of Al2O3, SiO2, FeO and Cr2O3 in the obtained concentrate, Cr/Fe ratio, some physical and chemical properties between gangue and minerals (i.e. specific gravity, magnetic property, color, etc.) designate the selection and combination of these methods and equipment (7)."

Jan 1, 2017