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By S. O. Ogden

As most of you have probably surmised from the title of my paper, I am here today to talk with you about the use of diesel engines in the American mining industry and whether or not the free choice to use such equipment will continue to be available to mine operators. Of course, I will present to you my prepared remarks, however, these remarks may be essentially academic in light of a news release, parts of which I would like to read to you. Washington, D. C., The Department of Health, Education, and Welfare today announced proposed new regulations to reduce occupational health risks to workers in the U. S. mining industries by requiring the removal of all diesel powered equipment from American mines by December 31st "While we do not have complete and conclusive information to quantify these health risks we feel it is prudent to undertake this restriction on the use of diesel powered equipment without waiting for the completion of studies that are currently underway to identify and quantify these health risks," said a Department spokesman. HEW has been concerned about the health risks of diesel emissions in the underground coal mines for some time and have investigations underway designed to conclusively demonstrate the nature and magnitude of any health risks. However, HEW has decided to proceed with these regulations without waiting for the final results of these investigations. Further, HEW feels there is sufficient probability that diesel health risks do exist in all mining applications and consequently, the proposed regulations will apply to all surface and underground mining operations. It goes on a little further and indicates that due to the necessity of finalizing these regulations without delay, a period of fifteen days has been provided to receive comments regarding these proposed regulations.

Jan 1, 1978

By Lawrence S. O’Rourke

Pricing for tantalum raw materials experienced explosive increases in the period 1978-1979, and-similar declines over 1980-1982. The causes for this are examined. Negative effects on the industry are highlighted. Analysis is provided of subsequent structural changes within the industry which minimize probability of future pricing excursions. Data on markets, sources of material, and outlines of concentration and extractive processes are reviewed. The conclusion is reached that expanded sources, future flat demand, and a broader international base of industry participants are principal forces in this restructure. Flat demand is reviewed as a function of increasing application of tantalum, but in more cost effective forms. This is driven by technical advance, notably in electronics applications.

Jan 1, 1986

By X. Nie

A new one-step process was developed to completely eliminate iron and directly obtain pure Ni, Co, and Cu chloride catholyte from nickel rich matte by low temperature (400 0c) chlorination roasting of Ni, Co, and Cu with HCl and leaching with water (PH 7). The effects of roasting temperature, time, oxygen potential and HCI addition and leaching temperature, pH, H2S04 addition and residue sulphur on the recovery of metals and purity of leaching solution were investigated. More than 99 % of Ni and Co and 95 % of Cu in the matte was directly extracted into the solution while 99.995 % of Fe remained in the residue. The iron concentration in the leaching solution was less than 3.6 X 10-5 mol/L.

Jan 1, 1994

By P. Zhu

The leaching behavior of copper powders recovered from waste printed circuit boards (WPCBs) was investigated using electrogenerated chlorine and aeration in a sulfuric acid solution with added NaCl and CuSO4. Various parameters were studied to understand the mechanism of the copper leaching. When the current density increased from 0 to 0.1 A/cm2, the temperature from 30 to 60° C, agitation speed from 100 to 400 rpm, and the size ranged from below 75 to 150 µm, the leaching ratios of copper powders increased. The leaching kinetics were analyzed using a shrinking core model: 1-(1-X)1/3 = kt, and the leaching process was chemically controlled with an activation energy of 14.7 kJ/mol due to Cl- ion catalysis. The ratios of [Cu+]/[Cu2+] at various temperatures (30, 40, 50, 60 and 70° C) showed a periodic variation with the increasing of the leaching time. The redox potentials of the leaching solution and copper leaching ratios in different conditions were measured. The result indicates that dissolved oxygen achieved the dissolution of coppers and electrogenerated chlorine can promote the dissolution of copper powders and improve the reaction rate of kinetics in the presence of oxygen.

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Nucleation and growth of copper on 316L stainless steel from synthetic acidified copper sulfate was studied in the absence and presence of chloride ions and/or organic additives – HydroStar® 4208, DXG-F7® and Cyquest® N-900 – using a potentiostatic technique. The current–time data obtained at 0.16V versus the SHE were analyzed using nucleation and growth models. Scanning electron microscope (SEM) images of deposits produced at 300 A/m2 show that the addition of 20 mg/L chloride ions increased the size and reduced the number of copper nuclei. Potentiostatic current–time data from the electrolyte without organic additives, and confirmed by SEM images, indicate progressive nucleation with two-dimensional growth under diffusion control. None of the organic additives studied at a concentration of 2.5 mg/L with 20 mg/L chloride changed the nucleation and growth mechanism, but the additives increased the number and reduced the size of copper nuclei, leading to more uniform coverage of the stainless steel substrate.IntroductionElectrowinning of copper is an important process in the manufacture of high-purity copper metal. Approximately 20 percent of the world’s refined copper is produced from acidified copper sulfate solutions by electrowinning (Schlesinger, Sole and Davenport, 2011). In many plants, copper is electrodeposited on AISI 316L stainless steel substrates for a period of 6-7 days, after which the copper is stripped from the blanks. Even though the deposition time for a commercial copper electrowinning circuit is around one week, it is critically important to control the nucleation, growth and nature of the initial deposit (Sun and O’Keefe, 1992).Deposit morphology and structure are influenced by the real current density at the electrode surface. The real current density across the cathode surface is made uniform by proper design of the electrowinning cell and electrodes and careful operational practice. Even with good design and control, some current maldistribution occurs. The outcome of severe current maldistribution is poor deposits that affect product quality and/or increase energy consumption. To combat current maldistribution and create a larger operating window in terms of current density, temperature and copper concentration, small amounts of organic smoothing agents – traditionally, guar products – are added to copper electrowinning electrolytes. Moreover, these additives inhibit the growth of copper nodules and lead to improved deposit quality by producing bright, smooth and dense cathodes.Recently, the use of polysaccharides, such as HydroStar 4208 and DXG-F7, and polyacrylamides, such as Cyquest N-900, has been reported in commercial electrowinning tankhouses as replacements for guar (Ashford, Clayton and Sandoval, 2012; Robinson et al., 2013; Sandoval, Morales and Bernu, 2010). However, little information has been published on the effect of these new organic additives, especially regarding the nucleation and growth mechanisms of copper electrodeposits in their presence."

Jan 1, 2016

By E. A. Rychkun

Mining and environmental objectives have traditionally been in conflict. This conflict reflects a delicate balance between the need to spend money to protect the environment, and the need to save money by extracting minerals efficiently. In an increasing number of cases, profit margins diminish rapidly with new environmental regulations and reactionary measures. Forced cleanups and increasing restrictions are unwelcome expensive processes. A practical solution lies in planning rather than reacting. This requires the ability to precisely quantify and qualify environmentally sensitive problems by providing effective engineering tools to model, visualize and analyze subsurface conditions. Prevention of environmental conflicts, and effective cost control are both rooted in the mining company's ability to construct accurate models, monitor changes, assess contamination risks and to design effective remediation plan. This paper presents a case study where these issues are addresses through the application of a new and innovative technology.

Jan 1, 1993

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Nucleation and growth of copper on 316L stainless steel from synthetic acidified copper sulfate was studied in the absence and presence of chloride ions and/or organic additives (HydroStar® 4208, DXG®-F7, Cyquest® N-900) using a potentiostatic technique. The current-time data obtained at 0.16V vs. SHE was analyzed using nucleation and growth models. Scanning electron microscope (SEM) images of deposits produced at 300 A m-2 show that the addition of 20 mg/L chloride ions increased the size and reduced the number of copper nuclei. Potentiostatic current-time data from the electrolyte without organic additives indicate progressive nucleation with two-dimensional (2-D) growth under diffusion control. SEM images obtained confirmed progressive nucleation with 2-D growth. 20 mg/L Cl- and 2.5 mg/L organic additives did not change the nucleation and growth mechanism, however the additives increased the number and reduced the size of copper nuclei leading to more uniform coverage of the stainless steel substrate.INTRODUCTION Electrowinning of copper is an important process in the manufacture of high purity copper metal. It is approximated that 20% of the world’s refined copper is produced from acidified copper sulfate solutions by electrowinning (Schlesinger, Sole, and Davenport, 2011). In many plants, copper is electrodeposited on AISI 316L stainless steel substrates for a period of 6-7 days, after which the copper is stripped from the blanks. Even though the deposition time for a commercial copper electrowinning circuit is around one week, it is critically important to control the nucleation, growth, and nature of the initial deposit (Sun and O'Keefe, 1992). Deposit morphology and structure are influenced by the real current density at the electrode surface. The real current density across the cathode surface is made uniform by proper design of the electrowinning cell and electrodes and careful operational practice. Even with good design and control, some current maldistribution occurs. The outcome of severe current maldistribution is poor deposits that affect product quality and/or increase energy consumption. To combat current maldistribution and create a larger operating window in terms of current density, temperature, and copper concentration, small amounts of organic smoothing agents (traditionally guar products) are added to copper electrowinning electrolytes. Moreover, these additives inhibit the growth of copper dendrites, which leads to improved deposit quality by producing bright, smooth, and dense cathodes."

Jan 1, 2015

By A. Konya

"INTRODUCTION Underground Mining and Construction projects face several challenges unique to the underground environment compared to the surface environment. The goals of an effective blasting program are the development of a blast pattern that minimizes cost, maximizes face advance, and provides the desired fragmentation and face profile. In addition to these , mines must consider the very real operational problems that occur such as drill deviation, ground vibration, and deadpressing or sympathetic detonation of explosives. These operation problems lead to increased costs and decreased production in the mine, hurting the bottom line. Combined with these problems, underground blasts can be difficult to monitor and evaluate due to tight spaces, dust during the blast obscuring video, and the need to evacuate the immediate area with no clear line of sight to observe performance. This creates an environment which most mines know that blasting can be improved in their underground operations, yet most are hesitant to change due to fears of the shot freezing, misfires occurring, and questions about how to achieve a proper design. The explosive companies and shot service providers also offer limited assistance or knowledge in the underground blasting realm, unlike with surface blasting, leaving many underground operations in the dark. It is for these reasons that most underground operations are operating decades behind the current technologies and incurring significant costs, both real and hidden, from there blasting operations. This paper discusses philosophical changes to designs that need to be made for effective design and modifications of underground blast patterns to prevent deadpressing and precompression of modern explosive products (Konya, Konya, & Worsey, Modern Blasting Method Selection, 2017). While numerous different methods of underground heading development exist, there are two types that are used in a majority of mines around the world, these are the burn cut and the V-cut. The burn cut is a parallel cut that has holes that go straight into the face and are primarily used in smaller opening (due to ability to pull deep rounds with smaller room widths) and metal mines (helps in ore dilution and greater fragmentation). The V-Cut is a cut that uses angled drilling towards the center of the face (in the traditional method) and is primarily used in underground aggregate operations due to its cheap cost but larger fragmentation sizes and greater throw of the muckpile. This paper will discuss these two forms of cuts specifically with the understanding that modifications to these can be applied to other parallel and angled underground heading techniques. BURN CUT The burn cut is one of the older forms of underground blasting, where a part of the blast (burn) of a shot is heavily loaded with additional empty (relief) holes with the goal of smashing (aka burn) and pushing/blowing all the material in the burn out to provide relief for subsequent blastholes. The relief holes in the burn cut provide a parallel relief for the holes that are firing to break too creating a second plane of relief, however these are extremely small and can cause many problems if a design is improper."

Jan 1, 2018

By E. Watkins, S. J. Schatzel, K. Ajayi, V. Gangrade

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research related to unconventional gas wells positioned in abutment pillars associated with active longwall mining in Southwestern PA. The Ventilation and Explosion Prevention Team at NIOSH is working toward predicting and characterizing a hypothetical casing breach and its effect on the safety and health of mine workers, gas well workers, and the general public. An important aspect of this research is to distinguish coalbed gas from shale gas in the mine environment as an indicator of a casing breach. Another noncoal gas source exists in the region in the form of underground gas storage fields which also have the potential to migrate towards mine workings. During a potential gas breach, the addition of excess natural gas to coal mine environments will exceed the anticipated ventilation loading and can create a mine explosion hazard. A methodology has been developed to distinguish these gas sources. Gas samples from the three sources were analyzed by gas chromatography, and interpretive methods were applied to distinguish the populations graphically and statistically. Bivariate plots using the hydrocarbon index and the normalized molecular ratios showed that the sources occupy different regions of the graphs. All samples of non-coal gas contained under 2% CO2, and all coal samples included greater than this amount. A multivariate T-squared (T2) test analysis relating comparing data in pairs showed a low p-value (dimensionality parameter) and a high T2 test statistic for all comparisons, indicating that these sources are different and distinct gas populations. Ultimately, stakeholders from the mining and gas production industries can utilize this method to identify gas sources and a potential casing breach.

Mar 2, 2022

By Allan J. Breitenbach

Heap leach operations provide a low-cost method for recovering gold, silver, and copper metals from low grade ore materials. The processed ore materials are stacked in controlled lifts on a lined pad facility for heap leaching. A controlled barren solution is applied to the heap ore surface by sprinkler or drip emitter irrigation, and ore metals are leached into the solution for collection and extraction in plant process facilities. The leach pad and solution collection facilities are lined with impervious materials for containment of all process solutions. The liner system typically includes a composite geomembrane and clayey soil liner with a protective drain cover fill to maximize solution recovery and protect the underlying groundwater conditions. This paper discusses the types of pad liner systems currently used by the mining industry and the "good, bad, and ugly" lessons learned in engineering practice over the last 10 years in the design and construction of heap leach pads.

Jan 1, 1999

By Wei Li

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium chloride and the microwaveabsorbing characteristics of the resulting reductive products were investigated; the reduction degree of the reaction was deduced to be . Results show that the activation energy is 112.03 kJ/ mol when NaCl is used as catalyst, lowering to 23.11 kJ/mol for the final stage activation energy using sodium silicate as a catalyst. There is a sharp change in the reduction rate constant at temperature ranges of 1,223 K - 1,273 K and 1,373 K - 1,423 K. Microwave-absorbing characteristics of reductive products were measured by the method of microwave cavity perturbation. It was found that microwave-absorbing characteristics of reductive products obtained at temperatures of 850° C, 1,100° C and 1,150° C show sharp changes. Through X-ray diffraction (XRD) characterization, it was found that the formation of Fe occurs at a temperature of 900° C during the reduction process of ilmenite concentrate. The decrease of FeTiO3 content results in the decrease of microwave-absorbing characteristics, while the increase of Fe content gives rise to the increase of microwaveabsorbing characteristics. The decreasing trend is larger than the increasing trend, which is the main reason for the sharp changes in the microwave-absorbing characteristics of reductive products at the temperature range of 850° C to 900° C. When the decreasing trend is smaller than the increasing trend, it becomes the main reason for the sharp changes in microwave-absorbing characteristics of reductive products at the temperature range of 1,100° C to 1,150° C. Kinetics results show that sodium chloride can catalyze the carbothermic reduction of ilmenite, and microwave-absorbing characteristic investigations indicate that microwave heating can be used in the carbothermic reduction of ilmenite.

By E. Watkins, M. B. Daza

Although there have been great advances regarding the understanding of mine fires in underground mines in the last century, fires remain high risk incidents. During fire scenarios, many crucial decisions and actions can be made that greatly influence the outcomes of these scenarios. Underground worker decisions are mainly based on training and experience, which in some cases can be complemented with previous analysis of fire effects. In order to review the guidelines that should be taken into account for this kind of examination, a numerical analysis of effects produced by a shuttle car fire under five different ventilation conditions was carried out. The analysis provides some insightful recommendations for firefighting personnel such as time for direct attack and best attack position for first responders and fire brigade groups. Also, the most critical parameters for each scenario were determined. Finally, all results were systematically organized and a first approximation of a fire classification based on the tenability limits was provided for first responder and fire brigade groups. The methodology used in this study for the fire classification could allow for the most appropriate decisions by firefighting personnel increasing the probability to put fires out without compromising their health and safety. INTRODUCTION While there have been great advances regarding the causes of mine fires in underground mines in the last century “small fires have occurred and always will occur in underground mines” (Conti, Chasko, Wiehagen, & Lazzara, 2005). The response time and decisions made during an underground mine fire are critical elements that have direct influence on the event outcome. Mine fires can grow in size quickly causing catastrophic consequences, thus rapid and suitable response actions can result in the difference between an minor emergency situation and a disaster. Upon the confirmation of a fire, a decision must be made regarding whether to fight the fire or evacuate the mine. Even though all underground coal mines possess emergency response plans and firefighting personnel are highly trained, decisions can be complemented with previous numerical analyses. Such analyses could contribute with the knowledge of potential fire effects and consequently with fire preparedness in the mine. Preparedness in underground mines is an important element to reduce the probability of the negative consequences of a mine fire. The time elapsed between the detection of the fire and response in the early stage is a serious component since small fires can produce larger and more serious consequences. If a mine fire cannot be put out within the short time after discovery, the chance of getting the system back in balanced or the success of safely controlling and extinguishing a mine fire is reduced (Conti et al., 2005, Conti, Chasko, Wiehagen, & Lazzara, 2000, Trevits, Yuan, Teacoach, Valoski, & Urosek, 2009, Brake, 2013). As confirmed by Conti and others, if a mine fire cannot be controlled by direct firefighting methods the probability of extinguishing the fire, without sealing is greatly reduced (Conti et al., 2005). However, response actions such as direct extinguishment must be carried out without compromising the health and safety of the firefighting personnel (Kim, Lönnermark, & Ingason, 2010).

Jan 1, 2019

By Xu Xiaohe, Zhou Jiandong, Luo Shihui, Zhang Liqun

Recently, the research and applications of ES (Expert Systern) have been put forward actively in many mining fields in China. After various ES applications or instances are introduced, the paper has especially focused on the exclusive properties of a mining system different from any other system and the problems of the existing mining ES applications. And a synthesis methodology has been introduced in order to develop a applicable ES application

Jan 1, 1996

By B. J. Sauer

Misapplication of ac induction motors for mine crusher and mill applications has long been a frustration for the driven equipment supplier and the mine operator. Proper selection of ac induction motors is critical to providing efficient production. This paper focuses on the selection of ac induction motors for gyratory crusher, conecrusher and grinding mill applications. The criteria for motor selection includes: proper enclosure, driven equipment torque requirements, bearing life, temperature rise, starting requirements, ambient temperature, altitude and accessory requirements.

Jan 1, 2002

By L. G. Austin

Equations are derived to allow for different mean velocities of axial flow for different sizes of particles in fully mixed ball mills. The equations are modified to allow for the exit classification that occurs in grate-discharge autogenous and semiautogenous tumbling mills. An approximate treatment is given that applies for other forms of residence time distribution, provided that the mill contents are close to fully mixed.

Jan 1, 2000

By P. A. Hendricks

The surface coal mining industry in the United States employs over 50,000 people and is responsible for 60% of domestic coal production. This represents a very significant contribution to our national economy and an important source of highly skilled and well paying jobs. The U.S. Bureau of Mines (USBM) has targeted surface mining as an important research priority to reduce the social and economic costs associated with surface mining injuries and fatalities. USBM safety research focuses on the development of technologies that can enhance productivity and reduce mining costs through a reduction in the number and severity of mining accidents. This report summarizes a number of completed and ongoing research programs that address a broad range of surface mining safety problems. Research methods are described, and research products which are suitable for industry implementation are highlighted.

Jan 1, 1994

By Ernest F. Giovannitti

A couple of years ago, one of the major television networks produced a series on the environment. One episode in the series dealt with the nation's solid waste problem and some of the research being done to solve it. It was interesting to listen to one researcher who was attempting to develop a glass that when broken would dissolve in water. It was said that using this glass would eliminate over 100 million tons of solid wastes each year. At first glance, it would appear that this research-effort would make a significant contribution to environmental pollution control; however, if one pauses to consider the water, he can see that this solution to the solid waste problem may well contribute to a water pollution problem. The dissolved material must either end up in our surface streams or be removed in waste treatment systems. Either alternative may have a more adverse effect on the environment than the original problem. With today's emphasis on the environment, it is important that the effects of our activities be studied in depth. Then, by properly planning the activity, the adverse effects can be minimized. The coal mining industry 100 years ago was in the same boat, as our glass maker, is today. Unfortunately, it too failed to consider all the effects of its activities and as a result, in Pennsylvania, there are over 5000 miles of streams adversely affected by coal mine drainage. The situation is improving, however, because mine operators are beginning to recognize and accept the methods for controlling coal mine drainage. The purpose of this paper is to discuss the measures for the control of coal mine drainage and to set forth the factors that affect these controls.

Jan 1, 1972

By P. Bevilacqua, G. Vallebuona

Empirical models are now used for predicting the performance of hydrocyclones in terms of capacity. cut size (d50.c), water split and partition curve. These models (such as the model by Lynch and Rao and the model he Plitt) were developed and checked for hydrocylones with diameters larger than 4 in. However, for smaller-diameter hydrocyclones, little empirical modeling has been done. This paper reports on an extended experimental research program on small hydrocyclones. For these cyclones, the suitability of existing empirical models was investigated and their accuracy was compared. To improve the predictive capability of these models to small cyclones modifications to the equations are proposed.

Jan 1, 1996

By Patrick R. Taylor

This paper presents a fundamental study of the thermodynamic and kinetic effects of copper and iron on gold-cyanide leaching. It quantifies the solubilities of the impurities, complex formation, and kinetic effects. The necessity of solution recycle, to meet environmental standards, requires that fundamental information be generated to characterize behavior and allow the identification of treatment methods. Mathematical descriptions of both solubilities and kinetics will be presented

Jan 1, 1983

By N. T. Rempe

The underground voids that result from mining provide opportunities for deep geologic waste disposal (DGWD). Such disposal could solve many environmental problems. DGWD takes careful planning, technology transfer and true partnership between waste generators and mine/repository operators. The US government is now planning on using specially mined excavations to dispose of radiotoxic and mixed waste. Using the experience gained from the domestic projects that are now in preparation and from foreign repositories that are now in operation, US mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1998