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By J. Jorge, J. Mariño-Salguero, B. Álvarez-Rodriguez, J. M. Menéndez-Aguado, J. J. de Felipe

"This work focuses on the characterization of heat generation during dry fracture by direct impact of a tantalum ore. Moreover, an attempt was made to quantify the heat energy loss to the environment during the grinding process of a ball mill. The study was carried out using mineral samples from a Spanish mine that were characterized by measuring their density and specific heat. During the experiments, increases of temperature ranging from 5.9 to 7.3 °C after the fracturing process were observed. A numerical model was then applied to calculate temperature distributions through the mill wall. Three possible combinations of heat transfer coefficients were analyzed, from (1) Kapakyulu and Moys, (2) Duda and (3) the heat transfer laboratory of Universitat Politècnica de Catalunya. The models with the coefficients from Kapakyulu and Moys and the heat transfer laboratory of Universitat Politècnica de Catalunya were found to provide results that were in best agreement with the experimental data. IntroductionEvery year, several billion tons of metallic ores, minerals, cement and other solids used in the ceramic and chemical industries are subjected to size reduction in ball mills around the world. The U.S. Department of Energy (2005) reported that in the United States about 29 percent of the total energy used by the mining industry, or 0.4 percent of total U.S. energy consumption, is used in comminution. In Canada and Australia, comminution is responsible for about 2 percent and 1.5 percent of total energy use, respectively. In nonindustrialized countries where mining constitutes higher fractions of their industrial sectors, comminution costs represent a significant contribution to mine operating costs. The specific energy consumption values for the grinding of these materials typically range from 5 to 50 kWh/t. Thus, a significant amount of electrical energy is consumed in the ball mill grinding operation (Aguado et al., 2006; Gupta and Sharma, 2014). Grinding can represent up to 50 percent of the direct operating cost in a mineral processing plant, especially as comminution devices operate in highly inefficient ranges of 4 to 8 percent (Wang, Yang and Yu, 2012)."

Jan 1, 2017

By Zhiguo Chang, QINGXIANG CAI, Ebelia Manda, IZHAR MITHAL JISKANI, XIANG LU, Wei Zhou, Saleem Raza Chalgri

The concept of mine safety is highlighted in the literature of sustainable mining but not extensively discussed. This study analyzes various aspects of underground and surface mine safety and emphasizes its importance in the context of sustainable mining. More specifically, this research attempts to find the relationship between mine hazards and demographic characteristics, examine and compare the perceptual difference among miners, and determine the impact of mine hazards on workplace safety and safety climate. Descriptive analysis, chi-square test, independent samples t test, and linear regression modeling were conducted to achieve study objectives. Results confirmed that mine hazards were significantly associated with age and experience. Miners perceived lower levels of management safety practices, followed by supervisor safety, coworker safety, and job safety. The analysis showed that underground miners reported lower safety scores than surface miners. There was a statistically significant difference between miners’ perception of safety climate (p < 0.05). The results showed that the higher prevalence of mine hazards predicts poor workplace safety and a low safety climate. The regression models revealed that mine hazards have a significant effect on workplace safety (p < 0.05) and safety climate (p < 0.05). In conclusion, the distinctive model of mine safety presented here contributes to the monitoring and design of comprehensive safety interventions and helps to better understand how certain factors interact on multiple levels to influence the overall safety of the industry. In this study, some suggestions are put forward to provide directions to develop a sustainable mine safety system.

Mar 27, 2020

By Charles T. Ford

In 1971, Bituminous Coal Research, Inc~ established a program to provide the coal industry with the necessary information and technical capability to investigate and evaluate potential problems concerning trace elements in coal and coal-related materials. The initial efforts at BCR in developing or adapting analytical procedures for the precise determination of trace elements in the parts per million to parts per billion range were detailed in a report titled "The Development of Analytical Methods for Determining Trace Elements in Coal and Coal-related Products." A subsequent reports contained descriptions of reliable analytical methods refined by BCR for determining mercury in coal and coal ash and also in coal mine water. his paper reports initial progress in applying recently-acquired trace-element analytical capabilities to solving potential coal industry problems. In this case, the effect of a coal-cleaning process on the distribution and removal of potentially harmful trace elements in coal was evaluated. Coal cleaning offers the possibility of controlling potentially harmful emissions resulting from combustion of large tonnages of coal by removing the pollutants prior to combustion.

Jan 1, 1977

By Randy Reed, Barbara J. Arnold

Respirable crystalline silica poses a significant health risk, with the American Lung Association estimating that 2.3 million workers are exposed to silica in the workplace. This includes mine workers as well as those in many other industries. Reducing dust formation is sometimes not possible so other methods to reduce exposure are critical. These methods include the use of surfactants to reduce airborne dust particles. However, it is the proper selection and application of surfactants that leads to reduced dust exposure. A discussion of how surfactants work, especially for silica dust, leads to guidance for surfactant selection followed by a review of technologies for their application.

Feb 1, 2024

By A. Moharana

A massive slide at Bingham Canyon wiped out a side of the pit and covered the main haul road in and out of the pit. All pre-slide mine designs and schedules were no longer valid. New designs and schedules needed to be developed quickly to provide management with information regarding the immediate post-slide production potential and the time needed to ramp back up to full production. At the time of the slide, an effort was already underway to convert Bingham?s in-house Medium Term Scheduling Process to MineSight®?s Schedule Optimizer (MSSO). One of the main reasons for doing this was to reduce the time needed to produce Medium Term Schedules at Bingham, which involves a complex shovel-based scheduling approach with shovel productivities based on shovel type and the types of mining cuts to which the shovel is assigned over each planning period. The objective of the schedule was to maximize shovel usage, satisfy mill feed requirements of four SAG mills with variable milling rates, and have flexibility in setting truck constraints. This paper will describe how the new MSSO-based mine scheduling process met the challenge of producing new schedules for Bingham in a minimal amount of time.

Feb 23, 2014

By J. Drew

Oregon Resources Corporation (ORC), an industrial minerals mining company, is currently engaged in the development of a new process design that will allow the unique paleo-beach placer deposits of southwestern Oregon to be mined efficiently and economically, creating an additional domestic source for chromite, garnet, and zircon. Engineering design has been guided by the variable geology and mineralogy of the paleo-beach placer deposits as well as the need for a dry tailing scheme that resolves a lack of water resources at the placer locations and at the same time eliminates the need for slurry settling ponds, typical of paleo-beach placer operations in North America. Metallurgical study of the placer material was grouped into four distinct samples based on marine terrace deposition, geological facies, and mineralogy. Because the metallurgical samples represented the extremes likely to be encountered in all future Oregon paleo-beach placer ores, the process design is highly dynamic and will successfully adjust to meet the production needs. Water availability at the mining area is seasonal and will not support a typical placer operation?s water requirement needs for heavy mineral concentration. For this reason, ORC has developed a plan to construct the ore processing facilities near Coos Bay, where a municipal source of water is available. Raw ore will be transported from the mining sites approximately twenty miles one way to the processing facility with return loads hauling tailings back to the active pit. The need to haul dry tailings, return dry material to the pit for reclamation, and limit the amount of water being purchased from the municipality has driven the design of a unique water reclamation system. BACKGROUND Location and Access Economic concentrations of ?black sand? or heavy mineral (minerals with specific gravity greater than 2.85) have been recognized and studied in marine placers from Coos Bay to the mouth of the Rogue River, a distance of approximately 75 miles along the southern Oregon coast (Hornor, 1918; Griggs, 1945)(Figure 1). ORC will begin mining existing reserves approximately 20 miles south of Coos Bay in a region known locally as Seven Devils. Ore will be trucked north to the processing site near Coos Bay via use of existing county and state roads, including U.S. 101. The available facilities at the processing site include highway, rail, municipal water and electricity, natural gas, and a deep water port. At the time of this writing, the rail line had been abandoned, but was being pursued by the International Port of Coos Bay. It is anticipated that this will be serviceable at some time in the future. History The southern Oregon marine placers have garnered the interests of miners since 1852, when present day beaches were exploited for gold. The beach deposits were small and irregular in nature and were easily washed away by the major storms the coast endures during the winter months (Hornor, 1918). [ ] In the 1920?s, deposits at the beach were followed upstream to their paleo-beach terrace origins (Pardee, 1934). These terrace placers were mined, but with little success, as the cost of mining and processing was greater than at the present day beach deposits. The greatest effort to understand and delineate the paleo-beach terrace placers came during World War II. As the need for a domestic source of steel hardening chromite was evident, the heavy mineral bearing placers of southwestern Oregon provided just that. The U.S. Geological Survey, under guidance from the Oregon Department of Geology and Mineral Industries, began exploration drilling of the paleo-beach terraces in 1940 (Griggs, 1945). This work was part of the investigation of strategic mineral deposits and would ultimately supply much needed chromite for the war efforts. The first mining efforts began in 1943 by the Humphreys Gold Corporation and the Krome Corporation (Griggs, 1945). Black sand

Jan 1, 2009

By Aimee A. Woolsey

Enterprise Unmanned Traffic Management is a holistic system concept evolving from technological developments in radio frequency where dynamic tracking can be added into current and emerging platforms. This is done through inexpensive RF sensors capable of real-time and cooperative, non-GPS tracking enabling digital visualization of assets, including unmanned aerial systems (UAS). The RF sensors are low size, weight, and power (SWaP), creating efficiencies in energy and material consumption while transmitting positions in real-time and at long ranges. Multiple UAS and other unmanned vehicles can be visualized for risk mitigation in operations,

Oct 17, 2022

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acidinsoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Nov 1, 2011

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acid-insoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Jan 1, 2011

By J. L. Kearns

The importance of optimizing equipment replacement decisions becomes more critical each year due to the rising costs of buying new equipment versus maintaining old equipment. Replacing equipment when it is physically worn out, or replacing it too soon or too late relative to its Economic Life (when it is economically worn out), is very costly. After extensive literature review and research, Kennecott has developed its Equipment Replacement Guide (ERG) system which identifies, evaluates, and justifies the replacement of uneconomical equipment. The system considers such critical factors as inflation, decreasing work capability, increasing maintenance/repair and operating costs, taxes, time value of money, return on investment, salvage value, and investment tax credit. These factors are used in a system of equations which balance the costs of new equipment against the total operating costs of old equipment. The solution of the equations determines the Economic Life of equipment. Replacement of equipment at the determined Economic Life will earn the specified, required return on investment that is used in the calculation of the Economic Life.

Jan 1, 1979

By Congcong Chen, Bo Ma

When assessing the safety of a tailings dam, the constant weight method (CWM) is one of the most commonly used methods. However, when the evaluation indicator value suggests serious defects, the evaluation value is often inconsistent with the actual situation. To address this issue, the variable weight method (VWM) is introduced to assess the safety of the tailings dam. Initially, a three-layer indicator system for dam failure safety assessment is built, and individual indicator values are divided into four grades. Then, an appropriate state variable weight function is constructed and relevant parameters are determined. Finally, a case study is illustrated to verify the effectiveness of the model. The assessment results of the VWM more closely represent the actual situation than that of the CWM, which is more helpful for decision makers and technicians to take scientific and reasonable precautionary measures, thereby improving the safety management of the tailings pond.

Oct 8, 2022

By Scott Rosenthal, Dave Gilkey, Theresa Stack, Daniel Autenrieth, Ciara Kremer

Jackleg drill operators are exposed to harmful levels of hand-arm vibration (HAV). Anti-vibration handles and gloves provide modest reductions in HAV exposures and forearm muscle exertion from the use of anti-vibration handles and gloves by jackleg drill operators. The goal of this pilot study was to investigate changes in HAV with the use of anti-vibration gloves and handles compared to forearm muscle exertion experienced by operators and measured with surface electromyography (EMG). Five subjects operated the drill under four different cases: no anti-vibration controls, anti-vibration gloves only, anti-vibration handle only, and simultaneous anti-vibration handle and glove use. Muscle exertion was expressed as a percent of maximum voluntary contraction (%MVC) and was compared using Welch’s ANOVA with Games-Howell post hoc comparisons. The case with both anti-vibration controls in use simultaneously (largest grip diameter) was associated with a mean %MVC of 36.13% during operation for all forearm muscles combined, which was significantly higher than that of the other cases (p < 0.05). There were no statistically significant differences in mean HAV exposures. The anti-vibration handle with anti-vibration glove case only increased the maximum allowable exposure time by 8 min as compared to the control case without any anti-vibration controls. These results suggest that the modest HAV exposure reductions from the use of anti-vibration handles and gloves may pale in comparison to the increased muscle exertion resulting from their use, and this trade-off among jackleg drill operators is a potential concern that warrants further investigation.

Jul 12, 2021

By M. Laliberte

"Gold-mine effluents are often characterized by high concentrations of copper, ammonia and cyanide derivatives (mostly cyanates and thiocyanates). While not acutely toxic to birds, this water can be acutely toxic to fishes and invertebrates. In many jurisdictions, the effluent requires further treatment in order to pass a mandatory requirement to be nonlethal to species like the rainbow trout (Oncorhynchus mykiss) or Daphnia magna. Using actual mine water, it has been demonstrated that aerated moving bed biofilm reactors will biodegrade the ammonia, cyanides, cyanates and thiocyanates, thereby removing the toxicity associated with these components. By removing copper by precipitation the water can be made to pass acute toxicity tests. Tests have demonstrated that the process is stable between 4 and 25°C, with no significant changes in the treated water composition. Once the biomass is acclimatized, the process is resistant to upsets and requires very little inputs except for phosphorus and air. Furthermore, it has been demonstrated that an anoxic reactor can be added downstream of the aerated reactors to remove nitrates if required.IntroductionThis paper will demonstrate that gold-mine effluents, which are toxic to fishes and invertebrates, can be made nontoxic by using a combination of chemical precipitation and biological oxidation.The typical composition of gold-mine effluents will first be described. The applicable legislation will then be introduced, with its requirement that the treated effluent be nontoxic. The toxicity of a typical untreated effluent will then be confirmed, and the sources of the toxicity identified. After that, a number of toxicity reduction treatment methods will be presented, and the selected method will be described.The lab tests that confirmed the efficiency of the treatment method will be presented, with three phases of testing as the understanding of the process gradually improved. Toxicity test results showing that the water is nontoxic after treatment through the temperature range will be presented."

Jan 1, 2015

By F. Wendling, R. C. Nascimento, S. S. Wendling

"The objective of this research is to study the quality of blast-furnace iron ore pellets with binary basicity 1 fired on a pilot scale using the two main firing processes that are presently in use in the world and comparing them. Currently, the great majority of pellet producers use the traveling grate process because of its higher production capacity. In this study, the physical and chemical qualities of the pellet feed, limestone, anthracite and bentonite were determined and the amount of additives for a blast furnace pellet with the defined basicity was calculated. The physical properties of the green and dried pellets were determined accordingly. Produced pellets, after being fired on a pilot scale using traveling grate and grate kiln, were subjected to chemical analysis and physical testing. No significant difference was observed in the metallurgical quality — that is, reducibility index (RI), reducing disintegration index (RDI) and swelling index (SWI) — of the pellets produced by both processes. However, a comparison of cold physical tests — tumble and cold compression strength — shows improved quality of the pellets fired using the grate kiln process.IntroductionThe development of human civilization owes much to iron and steel (Sun et al., 2015). Iron is the most used metal in the world, and it is the main component of steel, which is present in materials for structural engineering, automotive and general industrial applications (Liu et al., 2014). Increased global demand has led to a decrease in the resources of ore with high iron content (Zhang et al., 2015), and currently 95 percent of the iron ore in China needs processing before smelting as its iron (Fe) content is only about 30 percent on average (Liu et al., 2014).Pelletizing is a process to economically agglomerate iron ore pellet feed into pellet form. After balling, green pellets are conveyed to the final step of the manufacturing process (Pena, 1982). The process is a multifaceted one, involving high temperatures, air flow gas turbulence and complex equipment geometry (Larsson et al., 2009). The pellets are fed into blast furnaces, which are now predominantly used in the extraction of iron. Ore processing also requires physical separation, including crushing, grinding and water removal (Sun et al., 2015).The increase in steel consumption favors the exploitation of low-concentration ores and the production of pellets (Halt and Kawatra, 2014). Pellet quality is affected by various factors, such as their physical and chemical characteristics and their temperatures and residence times in the furnace (Halt, Silva and Kawatra, 2015). Different geological settings lead to a wide range of different minerals (Graça et al., 2015).This work aims to generate important information for the pellet industry in the area of physical and metallurgical qualities of the agglomerates obtained by two processes: traveling grate and grate kiln."

Jan 1, 2017

By N. Iverson, E. Haft, V. T. McLemore, M. Woodard, E. Owen

Present and emerging technologies are renewing interest in domestic rare earth elements (REE) production. REE deposits throughout the North American Cordilleran alkaline-igneous belt are being re-examined for their economic potential. In New Mexico, the mineral deposits found in this belt are associated with Eocene–Oligocene alkaline to calc-alkaline igneous rocks. Four areas in New Mexico have been examined for their REE potential. The chondrite-normalized REE patterns are similar for all four districts, even though different REE minerals are found. Crandallite, xenotime, bastnäsite and brookite are found in fluorite veins and carbonatites at Laughlin Peak. Bastnäsite was extracted during fluorite processing from 1954-1980 from the Gallinas Mountains, where samples as high as 8% total REE are found in fluorite veins. Other REE minerals include agardite, parasite, xenotime, and monazite. Allanite, thorite and as much as 8133 ppm total REE are found in fluorite veins in the Capitan Mountains. In the Cornudas Mountains, exploration along the outer edge of the Wind Mountain nepheline syenite laccolith and within phonolite dikes, plugs, skarns and carbonate-replacement deposits in Chess Draw contain as much as 3110 ppm TREE, hosted in eudialyte, monazite, bastnäsite, and calciocatapleiite.

Feb 1, 2023

By G. Nash

Despite further declines in production for some producers, 1986 proved to be a landmark year for the asbestos industry. The key event was the adoption of The Asbestos Convention by the Inter- national Labour Organization (ILO) and its 150 member countries. The document, entitled "Safety in the Use of Asbestos", reaffirms the international consensus on the "controlled-use" approach to chrysotile asbestos regulation. The decision of the ILO has come at a critical point in time. It represents a major turning point and provides an important building block for the long term future of the asbestos industry.

Jan 1, 1987

By D. R. Willmer

An understanding of how health and safety management systems (HSMS) reduce worksite injuries, illnesses and fatalities may be gained in studying the behaviors of health and safety leaders. These leaders bear the accountability for identifying, understanding and managing the risks of a mining operation. More importantly, they have to transfer this knowledge of perception, recognition and response to risks in the mining environment to their workers. The leaders’ efforts to build and maintain a mining operation’s workforce that consistently executes safe work practices may be captured through more than just lagging indicators of health and safety performance. This exploratory study interviewed six leaders in occupations such as site-level safety supervisors, mine superintendents and/or general managers at surface and underground stone, sand and gravel and metal/nonmetal mine sites throughout the United States, with employee populations ranging from 40 to 175. In exploring leaders’ perspectives on how they systematically manage health and safety, examples such as approaches to task training, handling near-miss incidents, identifying future leaders and providing workers with feedback offer insights into how leaders translate their knowledge and management of site-level risks to others.

Jan 1, 2018

By D. R. Willmer

An understanding of how health and safety management systems (HSMS) reduce worksite injuries, illnesses and fatalities may be gained in studying the behaviors of health and safety leaders. These leaders bear the accountability for identifying, understanding and managing the risks of a mining operation. More importantly, they have to transfer this knowledge of perception, recognition and response to risks in the mining environment to their workers. The leaders’ efforts to build and maintain a mining operation’s workforce that consistently executes safe work practices may be captured through more than just lagging indicators of health and safety performance. This exploratory study interviewed six leaders in occupations such as site-level safety supervisors, mine superintendents and/or general managers at surface and underground stone, sand and gravel and metal/nonmetal mine sites throughout the United States, with employee populations ranging from 40 to 175. In exploring leaders’ perspectives on how they systematically manage health and safety, examples such as approaches to task training, handling near-miss incidents, identifying future leaders and providing workers with feedback offer insights into how leaders translate their knowledge and management of site-level risks to others.

Jan 1, 2017

By J. J. Scott

As a Rock Mechanics investigator, the author has, Over his career, attempted to use his best knowledge in developing better rock control fixtures. Based on the experience of nine years of development of friction rock stabilizers, in 1980 he decided to launch a new investigation to develop a unique roof support fixture which would fit the coal mining market. The largest single user of roof bolts in the world is the American coal mining industry, historically using up to 100 million fixtures per year. In 1989 they used approximately 82 million fixtures.

Jan 1, 1990

By Evgueni Jak

Pyrometallurgy is an important sector of modern industrial society actively participating in solving current environmental, economic, materials scarcity and other challenges. Recent advances in analytical methods, experimental techniques, thermodynamic, phase equilibria and process modelling tools provide new opportunities to increase the productivity of pyrometallurgical reactors, the treatment of complex feeds and metal recoveries. Fundamental theoretical models can now be used to make a significant next step towards the development and implementation of computerised models describing real industrial processes—Virtual Reactors, and computer-aided smart-decision-making systems that may be called Pyro-GPS by analogy to GPS; these developments can facilitate knowledge-based improvement and optimization strategies. The implementation of these improvements require ongoing collaboration between researchers, industry and government