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By Jack E. Bailey

From a start in 1957, milling 3,000 TPD of copper ore, the Cyprus Pima Mining Company, which is located 20 miles south of Tucson, has expanded its operations four times, and is currently treating over 55,000 TPD of ore.1 The most recent expansion added a 14,000 TPD semi-autogenous concentrator to the operation. Shortly after startup in January, 1972, the semi -autogenous plant exceeded the designed tonnage rate.2 Ore from the mine is delivered to a 54 inch gyratory crusher and is reduced to a minus 8 inch product. From the crusher the ore is stacked on a surge pile and then reclaimed and fed to the two parallel grinding circuits. A 28 ft. diameter by 12 ft. long semi-autogenous mill and a 16.5 ft. diameter by 19 ft. long ball mill make up each grinding circuit. The semi-autogenous mills are in closed circuit with screens and the ball mill circuits are closed with hydro- cyclones. Rougher flotation follows the grinding operation. Concentrate regrinding and cleaner flotation is performed in Mill I, the older mill. The generalized flowsheet is shown in Figure 1.

Jan 1, 1975

By S. J. Boone, A. Poschmann, C. Pound, A. Pace

San Diego’s Stadium Conglomerate consists of poorly cemented cobbles, gravel, sand, silt and clay. Conventional laboratory and in-situ testing is not suitable for characterizing its engineering properties. Although the formation is often considered a “rock” its behavior is more readily modeled using soil mechanics. Static and seismic design of a tunnel for the Mission Valley East light rail extension required that the stress-strain characteristics of the ground be identified over a broad strain range. Geophysical methods and field plate load testing were used to develop a full non-linear stress-strain model of the expected ground behavior. Quantification of the coarse material distribution was also required for selection of tunneling methods and construction considerations.

Jan 1, 2001

By Aram Grigoryan

This paper addresses historical aspects and construction sequencing of the subway complex under Columbus Circle in Manhattan; the structural elements of the rehabilitation and new construction; and the challenges associated with design and construction. PB is providing engineering services to New York City Transit (NYCT) for the rehabilitation of the 59th Street/Columbus Circle Station Complex that services over 150,000 customers daily. The project involves structural repairs, modifications and new construction requiring underpinning and temporary supports, custom framing details, and construction staging procedures to meet stringent limitations within the operating transit station and around the Columbus Circle street intersections.

Jan 1, 2008

By Andrew E. Nevin

The government of India convened a precedent-setting meeting in New Delhi on Nov. 12, 2001.The meeting brought together regulators and the mining industry in an attempt to fix the industry’s mine development problems in that country. More than 150people attended the all-day session. Ram Vilas Paswan, Minister of Coal and Mines, chaired the meeting. Ravi Shankar Prasad, Minister of State for Coal and Mines, was also present. The secretary of the Department of Mines and the Joint Secretaries and Additional Secretary also participated. The Department of Mines’ mandate is for economic growth: to get new mine development going and to make investment in mining attractive for both domestic and foreign-owned companies.

Jan 1, 2002

By R. Wild

[When a blast furnace has a certain defined burden and is operated under fixed conditions of blast temperature, etc., the fuel efficiency is determined by the extent to which the reducing gases can remove oxygen from the burden in the furnace stack. This is determined by two distinct factors: 1) The uniformity of gas-solid contact, and 2) The ease with which oxygen can be removed from individual pieces of burden. This latter is often called burden reducibility. When burdens were poorly prepared the first factor was by far the most important and a study of the reducibility of individual lumps was of rather academic interest recent years good burden preparation with emphasis on sized material has led to greatly improved gas distribution in the stack, and thus the second factor has become much more important and there has been a marked increase in interest in methods of measuring reducibility.]

Jan 1, 1964

By A. Noble

Traditional simulations of mineral processing circuits are solved by straightforward numerical techniques which require iteration to accommodate recirculating loads. Depending on the complexity of the simulated circuit, this solution technique can be inexact, computationally intensive, and potentially unstable. In this communication, an alternate calculation approach is presented, wherein an exact analytical solution is determined as a function of the individual units? separation probabilities. All the stream data, including recirculating loads, may be solved simultaneously, negating the need for iteration. Furthermore, with an analytical solution available, circuit analysis may then be utilized to diagnose the relative separation potential of the circuit. By integrating these tools, the authors have developed a software package for evaluating circuit configurations. This paper presents the theory, development, and limitations of the software?s methodology along with industrial examples which highlight the tool?s applicability to industrial circuits.

Jan 1, 2012

By Hasan Nizamoğlu, Z. Abidin Sarı, Aslıhan Demiraslan, M. Deniz Turan, Tolga Depci

In this study, recovery of copper from solid material (obtained by leaching of chalcopyrite with oxalic acid in the presence of hydrogen peroxide) with a copper oxalate structure was carried out selectively using HCl. The chemical composition of the solid was as 29.3%, 9.7%, and 13.3% for Cu, Fe, and S, respectively. Selective recovery of copper by degrading the copper oxalate structure with a low-solubility product (Ksp = 4.43 × 10−10) was performed by conventional leaching in the presence of HCl. The optimum leaching conditions were determined as 5 M of HCl concentration, 318 K of leaching temperature, 120 min of leaching time, 25 ml/g of liquid–solid ratio and 400 rpm of stirring speed. Under these conditions, approximately 77% of copper and 3% of iron were taken into the solution. According to the characterization of the leach residue that was obtained, the oxalate structure was degraded. Moreover, the results of XRD analysis showed that the sulfur (S) and cubanite (CuFe2S3) phases were mostly observed in leaching residues, and this was supported by the SEM-EDX data. Based on the results, it may be stated that selective copper extraction can be obtained from a chalcopyrite concentrate by a two-step leaching method using a conventional hydrometallurgical technique.

By Shemek Oginski

The 5 km (16,194 lf) of 6.1m (20 ft) diameter TBM driven tunnel built by the J.F.Shea Co. will serve as sewage overflow storage. The TBM tunnel and four connecting tunnels excavated by drill and blast methods in hard granite will remain unlined. Based on the Geotechnical Baseline Report (GBR), the Contract documents provided a design with no required pattern of rock bolts, no probing, no pre-excavation or consolidation grouting, and lastly, no final lining of the tunnels was deemed necessary. This paper will provide a general overview of these topics with the emphasis on the actual ground conditions encountered versus the projected conditions provided in the GBR and how the GBR reflected the design of the project. Proposed modifications to the temporary and permanent ground support will be presented and the necessity of probing and pre-excavation grouting will be evaluated.

Jan 1, 2005

Ceremonies for the induction of four mining industry pioneers into the National Mining Hall of Fame will be held Saturday, Sept. 13, 2008 at the Charles F. Barber Pavilion of the Museum Convention Center in Leadville, CO. This will be the 21st Annual National Mining Museum and Induction Banquet. The four inductees are Lew Eklund, 76, Carrie Jane Billings Everson (1843-1914), ?Colonel? William C. Greene (1851-1911) and Arthur L. Hawkesworth (1860-1905). Lew Eklund founded Eklund Drilling that is now based in Elko, NV. He invented many designs that play a major role in today?s mining industry. His Cyclo Blower and various sampling devices he designed helped to revolutionize gold deposit exploration by allowing mining companies to effectively sample microscopic gold. Carrie Jane Billings Everson discovered and proved a method for bulk oil flotation concentration of mineral ores, the precursor to modern froth flotation methods of minerals concentration. She patented her process in 1886. In the early 1890s, coworkers built and operated demonstration plants incorporating her bulk oil flotation process. ?Colonel? William C. Greene was responsible for the development of the great copper mining properties of Cananea, Mexico. In seven years, he went from ragged cattleman and adventurer to the greatest captain of industry the borderlands have ever seen. Arthur L. Hawkesworth was a master mechanic for Anaconda Copper. He invented the detachable drill bit. His invention generated tremendous savings for the mining industry in time, in dollars and in safer operating conditions underground. His bit?s long lasting contribution to improved mine economics is immeasurable. The 21st Annual National Mining Museum and Induction Banquet will begin with an open house and reception at 5:30 p.m. followed by the dinner and program at 7 p.m. The inductions will bring to 201 the number of mining ?greats? whose engraved photographs and biographical sketches are installed in the National Mining Hall of Fame.

Jan 1, 2008

By Nikhil Dhawan, Veeranjaneyulu Rayapudi

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

By Lei Pan, Venkata Atluri, Xuming Wang, Yuesheng Gao, Jan D. Miller

The wetting characteristics and water film stability at the talc surface have been studied, particularly the effect of polysaccharides such as guar gum, starch, and dextrin. Talc is a gangue mineral in the flotation of base metal sulfide ores, precious metal sulfide ores, and platinum group metal (PGM) sulfide ores. Talc surfaces were investigated using surface analysis techniques including atomic force microscopy, high-speed video bubble attachment measurements, and wetting film stability measurements using a synchronized tri-wavelength reflection interferometry microscope (STRIM). In the presence of polysaccharides, there is a significant increase in bubble attachment time at the talc surface, but only a slight change in contact angle, which suggests that polysaccharide depression of talc is due primarily to the slow rate of bubble attachment and not due to a change in contact angle. The critical rupture thickness (hc) for a hydrophobic talc surface was found to be 56 nm, while the hydrophilic phlogopite surface of similar structure has an equilibrium film thickness (he) of 25 nm. At low polysaccharide concentrations, the wetting films formed on the talc surfaces were unstable, but at high concentrations the wetting films became stable with similar thickness values as the critical rupture thickness, and bubble attachment did not occur. However, it was found that the critical and equilibrium film thickness values do not change significantly with the polysaccharide type or concentration. The results from this research help us understand further details of film rupture and displacement during bubble attachment.

By Henry H. Roos

The productivity of the underground driller has increased 500-600% during the past 20 years. This increase is not due so much to improved percussion drills as it is to improved drill support equipment and modernization of mining methods, Efforts to mechanize drilling in mining operations were made as early as the late 1800's; and, patents on rock drill manipulating machinery date back to 1906. However, the great rush to mechanization began in the 1950's when the development of trackless mining methods gave mining engineers and equipment designers their first opportunity to create improved operating conditions for the equipment and to match the equipment with these conditions. Accordingly, this paper will summarize the developments of the past 20 years and will attempt a forecast of developments that can be expected during the next few years.

Jan 1, 1970

In spite of a global economy that continues to seesaw and a U.S. Congress that is at odds with the president and themselves, cities around the world are still spending billions on their infrastructure. And that bodes well for the underground construction and tunneling industry and the professionals who work in it. In June, 1,405 of those professionals gathered in San Francisco, CA for the Rapid Excavation and Tunneling Conference (RETC). In addition to the first rate technical programming, attendees were able to see first-hand the latest in tunneling technology from 127 exhibitors who occupied 152 booths. Two short courses preceded the conference and two field trips were offered following the conference.

Jan 1, 2011

By T. J. Lutz, J. L. Carr, J. A. Yonkey, C. C. Jobes

"Since 1984, the date of the first recorded fatality involving a remote controlled continuous mining machine, 38 miners in the United States have been killed when they were struck by a continuous mining machine. Proximity detection is a valuable tool for preventing fatalities, and the use of these systems is expected to significantly improve safety. Proximity detection provides a means to prevent accidents like these. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a series of underground tests to evaluate the accuracy and repeatability of proximity detection systems under a number of conditions such as varying the orientation and height of the personal wearable device (PWD), moving the PWD close to the trailing cable, and activating the machine’s mining mode. At the 2014 SME Annual Meeting, results from tests on first-generation proximity detection systems were presented. This paper will provide results from the similar tests performed with second-generation systems. The results show that performance has improved. For example, the negative impact of PWD orientation and the trailing cable has been reduced. However, some inconsistencies remain. Notably, performance changes dramatically when mining mode is activated. INTRODUCTION Since 1984 there have been 38 fatalities involving striking and pinning of the operator and other workers by the continuous mining machine (CMM) [1]. In August 2011, the Mine Safety and Health Administration (MSHA) published a proposed regulation that would require proximity detection systems on all continuous mining machines except full-face machines [2]. Proximity detection systems are designed to stop machine motion to protect miners from striking/pinning hazards. Several MSHA-approved proximity detection systems are commercially available. MSHA estimates that of the 38 fatal striking and pinning accidents that have occurred since 1984 involving CMMs, the use of proximity detection could have been a preventative factor in at least 28 cases [1]. Furthermore, MSHA estimates that proximity detection could prevent 20% of all deaths throughout the industry [3]. NIOSH researchers have been involved in the development and testing of proximity detection technology since creating the HASARD system [4] and have recently conducted research intended to develop more advanced proximity detection technology for CMMs [5,6,7,8]. In addition, NIOSH has also conducted research investigating how the signals of a proximity detection system propagate [9,10] and have developed a novel method for determining the location of a personal wearable device (PWD) relative to the magnetic field generators [11,12]."

Jan 1, 2015

By Paul D. Tomlingson

Part two of this two-part series covers the use of an integrated information system with administrative information, including error and absentee reports as well as open work files. Part one (ME, July, page 650) discussed conceptualizing and developing a maintenance information system. It explained what information is needed to manage such a system.

Jan 8, 1985

By Peter Bigwood

Whether drilling through tough clay or breaking rock, or facing the most severe conditions including mixed face ground, perched water and running and flowing sands, working under-ground certainly comes with no shortage of challenges. In an environment where the unknown is faced on a daily basis, tunneling contractors must be able to rely on their equipment to get the job done properly. Not only that, their equipment must comply with two of the highest priorities: safety and efficiency. In addition to being the number one concern, a proven safety record provides additional benefits to a company. A safe work environment serves as a key component to company growth, including the ability to remain competitive in bidding and maintaining higher-level, more challenging projects.

Jan 1, 2012

By Nikhil Dhawan, Ashwini Kumar, Yogendra Pratap, Himanshu Tanvar

India does not possess any soluble potash reserves and depends completely on imports. In this study, an attempt has been made to recover potash (K) values from the mica sample employing thermal and mechanical routes followed by leaching. Direct leaching of mica in different lixiviants is found to be ineffective with very low K-dissolution (1–5%). Heat treatment with different fluxes, such as NaCl, NaOH, and CaCl2, is carried out and almost 85% K-values are recovered. Mechanical activation of mica and with different calcium additives is carried out to recover potash values. K is recovered in leach solution in the form of soluble salts, such as K2CO3, K2SO4, and KOH, and leach residue consists mainly of calcium-alumino-silicates. Using mechanical activation with flux, it is possible to recover >95% K-values from mica sample. Mechanical activation with calcium-based flux is found sustainable in the recovery of K-values from mica.

By M. R. Shahan, W. R. Reed, S. Klima, T. W. Beck

"Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27% of the respirable coal mine dust can be attributed to longwall shield movement. Developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine their ability of foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used; compressed air (CA) and blower air (BA). Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For CA foam in 3.3 m/s (3.3 m/s (650 fpm)) ventilation at 3 minutes after application, 98% of agent A was intact, while 95% of agent B was intact on the roof. At 30 minutes after application 94% of agent A was intact while only 20% of agent B remained. For BA in 3.3 m/s (3.3 m/s (650 fpm)) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 minutes after application 74-92% of foam agent A remained, while 3-50% of foam agent B remained. CA foam seems to remain intact for longer durations and is easier to apply than BA foam. However, more water drained from the foam when using CA foam which demonstrates that BA foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able withstand a typical face ventilation velocity, establishing this technique’s potential for longwall shield dust control. INTRODUCTION NIOSH personnel have visited many longwall operations at various geographical locations in the U.S., conducting benchmark surveys to characterize current operating practices and dust control measures in use. Sources of respirable dust generated from the longwall face have been identified as: intake (10%), stage loader (20%), shields (27%), and shearer (43%) [1]. Dust generated from the shearer, armored face conveyor, and the stage loader can mainly be controlled by water sprays and increases in ventilation air quantities, however, research has demonstrated limited effective controls for dusts generated by shield movements [2]. One possible approach to mitigating shield dust generation is to apply a layer of water or foam to the shield-roof interface. Once this interface is blanketed with foam or water, dust will be less likely to become airborne and contaminate the airways over the personnel walkways. Though water is an abundant and common dust control measure, roof applications have limited success because water is unable to remain in-place in adequate quantities for the necessary duration between application and shield advance. Past and current testing of foam for material properties has shown that it has longer applicability times, ranging from 10 to 60 minutes [3] and has shown better performance for dust control, ranging from 19-96% improved efficiency over water [4, 5, 6, 7, 8]. The majority of this foam dust control research has focused on dust control efficiency at the longwall shearer or continuous miner cutting drum."

Jan 1, 2017

The theme of the 2012 North American Tunneling conference (NAT) was ?Tunneling: Driving Value.? This theme best reflects where the tunneling and underground construction industry is to-day. Major advances that have been made in technologies have provided tremendous improvements in productivity, which, in turn, have allowed the industry to deliver more cost-effective and less disruptive solutions to the nation?s infrastructure needs. Despite a weak economy, domestically and globally, cities and states continue to spend billions on infrastructure improvements. For the underground construction industry, that means more transportation and water, wastewater, storm water projects and other underground structures. And, for each project completed, underground construction and tunneling technology grows. The NAT conference, put on by the Underground Construction Association (UCA) of SME, provides an outlet for technology transfers among professionals. This year?s conference, held in Indianapolis, IN June 24-27, attracted 918 attendees, up from 803 at the last NAT in 2010. The accompanying exhibit also featured 116 exhibitors occupying 140 booths. That was up from 108 booths in 2010. So, the meeting continues to grow as underground construction professionals throughout the world seek to learn from their peers.

Jan 1, 2012

By Yuting Xue, Gamal Rashed, Zoheir Khademian, Connor Brown, Khaled Mohamed

Ground falls in U.S. underground coal mines can lead to significant consequences, including loss of life, injuries, damaged equipment, and production stoppage. Improving the safety of the workplace is of utmost importance for mine workers and the U.S. economy. The Mine Safety and Health Administration (MSHA) accident/injury/illness dataset provides short narratives for reported incidents, including ground-falls. The main objective of this study is to develop a framework that includes: 1) utilizing machine learning algorithms to categorize ground-fall incidents from narratives based on the main cause of the occurrence and 2) demonstrating an example of a user-friendly visualization to display injury/fatality trends from narratives in U.S. coal mines between 1983 and 2021. The developed framework was tested on a subset of the data and achieved an average F1-score of 96% in categorizing the incidents. The outcome will help identify areas requiring additional research and innovative solutions to reduce severe occupational hazards.

Feb 1, 2024