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By Stan Tang, Yiming Sun, S. Amir Reza Beyabanaki, N. Sathi Sathialingam

The Kurve mixed-use development project including a 22-story tower at 2801 Sunset Place was constructed on a site consisting of a roughly rectangular-shaped lot at the intersection of Wilshire Boulevard and Hoover Street in Los Angeles. Two Metro Red Line tunnels, with depths of approximately 30 feet and 58 feet, respectively, cross below the building at distances of approximately 1 foot to over 63 feet from the site. This paper presents numerical modeling performed to evaluate the ground and tunnel behavior in response to building construction. Results of geotechnical instrumentation and monitoring undertaken during the building construction are also discussed.

Jun 13, 2023

By N. Moemise, M. B. Shongwe, P. A. Olubambi, M. M. Ramakokovhu

"Near-infrared (NIR) spectroscopy sorting technology is incorporated in an automated optical mineral sorter that can discriminate between materials using the differences in characteristics when exposed to near-infrared radiation. During September 2014 to April 2015, a pilot plant that utilized NIR technology to discriminate between kimberlite and waste materials was commissioned to determine the viability of including this technology in the diamond winning process flow sheet at Cullinan Diamond Mine. The plant was used to minimize the waste content in the size fraction -70+35 mm that reports to the crushing section and then to the dense media separation process. This paper describes the initial test work, conducted at Mintek, that led to the decision to conduct a pilot-scale study. The mineralogical characterization of the feed and product streams to establish the sorting criteria and the operational data obtained during the pilot plant campaign are described. The results indicated a good possibility of discriminating between the kimberlite and waste material using NIR technology. However, the consistency of discrimination was not good enough to avoid the risk of potential diamond loss. Furthermore, a lower than expected availability of the machine reduced the throughput capabilities. IntroductionUsing near-infrared spectroscopy (NIRS) technology for ore sorting is a new concept for the mineral processing and mining industry. NIRS has been used for decades in the laboratory for the identification of pure minerals, and has its roots in the recycling, food, and pharmaceutical industries (Salter and Wyatt, 1991; Robben et al., 2009). Ore sorting in itself is not a new concept; it was introduced during the Stone Age with handsorting being the first method to separate valuable materials from gangue (Wills and Napier-Munn, 2006; Sassos, 1985). However, over the years the scale of mining has increased and hand-sorting has become challenging to implement (Joensson, 2014).Sensor-based sorting is an advanced technology that can help overcome problems such as ore dilution experienced in mineral processing operations. The benefits are lower energy and water costs, reduced ore dilution, lower environmental impact, and improved profit margin (Mathew, 1974; Jonsson, 2014; Salter and Wyatt, 2009; Death et al., 2009). In sensor-based sorting, materials are mechanically sorted based on certain physical properties that are detected by a sensor (Dalm, 2013). Research has found that with NIR scanners it is possible to obtain a ‘fingerprint’ of a sample that is directly related to its mineralogical composition. According to Woutruba et al. (2009), molecules absorb NIR radiation by means of electronic and vibrational transitions. Nowadays, there are many sensors available in the market that utilize different material properties; the choice of a sensor is dependent on the mineralogy of the ore."

Jan 1, 2016

By Jean Igor Margem

Nestes dias materiais ecológicos como compósitos com fibras naturais em matriz polimérica estão chamando a atenção de pesquisadores científicos, devido ao seu bom desempenho na substituição de materiais como madeira, polímeros à base de petróleo e outros. Neste trabalho foram avaliadas as propriedades de tração de compósitos de matriz epóxi reforçados com diferentes espécimes de fibras lignocelulósicas. Compósitos reforçados com até 30% em volume de fibras longas, contínuas e alinhadas de malva, sisal e bambu foram testados em uma máquina Instron a temperatura ambiente. A fratura foi analisada por SEM. Os resultados mostraram alterações significativas nas propriedades mecânicas com a quantidade dessas fibras. Estas propriedades mecânicas foram comparados com outros resultados em compósitos testados em ensaio de tração. A análise da fratura revelou uma fraca interação da interface fibra / matriz, o que poderia ser responsável por um maior desempenho de algumas propriedades.

Aug 17, 2017

By J. A. Bradbury

N. A. Degerstrom, Inc. has constructed and operated a processing plant approximately five miles north of Soda Springs, Idaho for processing a byproduct phosphate treater dust from Monsanto's elemental phosphorus plant, also located in Soda Springs. The plant is designed to produce agricultural-grade phosphoric acid, gallium, and silver. The design capacity of the plant is 54.4t (60 st) of treater dust per day, which can produce 16,326t (18,000 st) of phosphoric acid, 6,600 kg of gallium, and 6,033 kg (194,000 oz.) of silver per year.

Jan 1, 1993

By Diego Berti Salvaro

A morfologia, dimensões e composição química de tribocamadas são fortemente dependentes das pressões e temperaturas existentes no contato e oriundas das reações das superfícies entre si, com a atmosfera, com os lubrificantes e contaminantes presentes no contato. No presente artigo foi analisada a formação de tribocamadas em pares DLCaço inoxidável testados por 180, 500, 1000 e 2500 horas em atmosfera de gás refrigerante R134a sem a presença de óleo lubrificante. A caracterização foi realizada por microscopia eletrônica de varredura espectroscopia de energia dispersiva (MEV-EDS) (morfologia e composição química) e interferometria ótica de luz branca (dimensões). Nas análises por MEV-EDS foram identificadas tribocamadas que se apresentaram mais pronunciadas nas superfícies do aço inoxidável sendo as mesmas oriundas de transferências mútuas entre os pares tribológicos bem como oxidação. A espessura das tribocamadas, por sua vez variou de 100 a 500 nm. Os resultados revelam que as tribocamadas são quimicamente estáveis e que suas espessuras não variam significativamente após mil horas de ensaio.

Aug 16, 2017

By Mark Colwell

This paper summarizes the results of a research project whose goal was to provide the Australian coal industry with a longwall installation roadway (faceroad) design methodology that could be utilized by suitably qualified colliery personnel. This goal was achieved in 2012 and the design methodology (and software package) is referred to as Analysis and Design of Faceroad Roof Support (ADFRS). The intended benefits to underground operations, in the provision of this information and resource, are a safer and more productive workplace.

By J. K. Afidenyo

Microbial pretreatment of a double refractory gold ore was investigated using a white rot fungus, Coriolus versicolor (ATTC 20869) to improve gold extraction. A series of preliminary tests were conducted to determine the amenability of the ore to fungus degradation. Pulp density, temperature, pH and retention times were the process variables considered. Both a single. Stage and two-step processes were studied to establish process conditions. During the single stage process, the ore was contacted with the fungus culture (biotic) for 3weeks at 30°C and pH 10.0. For the two-step process, the first step involves ore contact with the culture medium (abiotic) at 45°C and pH 10.0 followed by fungal contact (biotic) at 30°C. Results indicated that carbonaceous matter is not degraded but passivated by the fungus; as preg-robbing activities dropped significantly from 18.1% to below 1.0%. The single stage process resulted in higher gold recovery than the two-step process Gold ex-traction by cyanidation of the pretreated ore was 78.9% for the single stage compared with 15.0% for the untreated ore. In the two-step process, only 73.3% gold extraction was achieved. Application of the two step process conditions to a high grade flotation concentrate, resulted in 93.3% gold ex-traction as against untreated concentrate of 30.5%. The results show that the microbial pretreatment process degraded sulfide sulfur, passivated carbonaceous matter and enhanced gold extraction from double refractory gold ore and concentrate.

Jan 1, 2014

By Ryan Weaver, Travis Coleman

The drilled shafts that support transmission lines and substations have been increasingly subject to testing to assess the integrity of placed concrete. Cross-hole Sonic Logging (CSL) has been used, but large diameter shafts with challenging site access are generally more favorable to Thermal Integrity Profiling (TIP) testing. TIP testing assesses the shafts based on measurements of the concrete temperature during curing. The TIP results provide assessment of integrity both within and outside the cage, along with information about the alignment of the cage and concrete cover. This data has allowed shafts with imperfect results to be subject to more detailed structural evaluations. However, it may not be well understood how to use this additional information by designers and engineers. The purpose of this paper is to present TIP results of transmission line foundations, both with and without issues with integrity, including cage shifting, minimal concrete cover, or soil inclusions. The intent is to provide general guidelines of the issues that merit additional investigation and those that should be recognized as inconsistencies inherent to underground construction. BACKGROUND This paper is intended to discuss some of the drilled shaft evaluations made when TIP testing is performed. The authors of this paper were recently involved with a transmission line project that was designed and constructed for a Confidential Utility Client located in the Midwest United States. The project was delivered as an Engineering, Procurement, and Construction (EPC) contract with the electrical line construction company as the prime contractor. The contractor then subcontracted several parts of the work which included engineering for transmission line and foundation design, foundation construction, and third-party testing intended to evaluate the concrete homogeneity and integrity of the place concrete in the deep foundations. The testing method selected was Thermal Integrity Profiling Method B, which uses thermal sensors embedded in the concrete. The TIP testing was administered by Mr. Travis Coleman with GRL Engineers, Inc. Mr. Ryan Weaver with Burns & McDonnell served as the owner’s engineer and technical consultant for the utility and was responsible for reviewing submitted TIP reports and providing recommendations to the utility on their acceptance, and if there were any issues that would warrant further discussion and analysis.

Jan 1, 2019

The methods employed for the addition of uranium to steels and cast iron in the Physical Metallurgy Division are outlined. It has been found that the segregation of? uranium is a major problem in aluminum and/or silicon killed steels and that the cooling rate is important in al-lowing the segregate to settle to one area, which can subsequently be discarded. The unsegregated areas were found to be extremely low in total oxygen, acid insoluble aluminum (AizOg) and, in some cases, slightly lower in nitrogen. Uranium recoveries, based on analyses of the unsegregated areas, were quite constant, at about 45 per cent, regardless of the type of uranium master alloy used for the addition. No segregation of carbon, manganese, silicon, sulphur, phosphorous, chromium or copper was observed in these steels. In commercial heats, the recoveries ranged from 7 to? 29 per cent for ladle additions to oxygen converted steel. When the steel was fully deoxidized prior to the uranium addition, recoveries ranged from 49 to 66 per cent, regardless of the steelmaking process.

Jan 1, 1964

By J. Mrozowski, R. Kurowski, A. Chmielarz, Z. Szolomicki

PbSO4 is a commonly encountered component of the materials used in lead recycling (e.g. battery paste) and in by-products of metallurgical processes (e.g. residues from zinc hydrometallurgy, dust from copper smelting). Smelting of battery paste results in SO2 emission and in generation of significant amounts of hazardous ‘white slag’. Those adverse phenomena can be eliminated by removal of sulphur from the paste. Lead-bearing by-product materials are of polymetallic character with usually low Pb content, which makes lead recovery technologically difficult and uneconomic. However it can be successfully achieved by extraction of lead sulphate from solid phase with triethylenetetramine (TETA) water solutions. That compound has capability for selective solvation of a whole lead sulphate molecule. Virtually pure lead carbonate can be precipitated by means of saturation of lead-loaded aqueous TETA solution with carbon dioxide, and complete regeneration of the extractant is achieved by fixing of sulphate ion into gypsum through operation of calcium hydroxide suspension. The paper presents results of the lab and pilot scale studies into process of battery paste desulphurisation and recovery of lead from the residue of zinc calcine leaching.

Jan 1, 2014

By Mark A. Koestel

Cobalt-sulfide mineralization can he found in potentially economic quantities where permeable, basal Cambrian formations "pinchout" against Precambrian pal eotopographi c highs. These environments are common around the Saint Francois Mountains of southeastern Missouri and they share many similarities with the geologic environments of Zambia and Zaire in South Africa. Exploration for this type of deposit involves test drilling targets identified by trend analysis from past drilling, geophysics, geochemistry and a comprehensisve study of regional geology and isopach maps. Innovative ideas, new exploration concepts and insoluble residue geochemical methods may provide the necessary "edge" needed to complement basic geologic understanding leading to ore discovery.

Jan 1, 1987

By Robson Gambeta

A CLE Brasil possui uma subestação de 230kV que apresentou sérios problemas de trincas e rachaduras nas estruturas de concreto após alguns anos. Em alguns pontos a ameaça de queda era real. Foi iniciado um estudo de patologia das estruturas de concreto, com uma empresa especializada em recuperação estrutural para conhecer as causas e recomendar a melhor terapia estrutural a ser realizada. Após o estudo, definiu-se a terapia adequada das estruturas. Esta atividade foi classificada como de grande risco e teve foco na segurança da equipe e operação do sistema, de modo que todo o serviço fosse executado sem quaisquer incidentes as pessoas, ao meio ambiente e ou interrupções de energia elétrica. Havia desafios como realizar manutenção nas proximidades da linha viva, serviços em altura com utilização de andaimes, período de chuvas e ventos, trocas de equipes e anomalias. As estruturas tratadas foram Pórticos com 17 metros de altura, postes e suportes para isoladores, TPs, TCs, Seccionadoras e Transformadores. A atividade durou 04 meses e contabilizou 5.752 horas de trabalho. Os resultados foram significativos e dentro do esperado, sem ocorrência de incidentes, prolongamento da vida útil e aumento considerável da segurança da equipe e do sistema de distribuição.

Jul 31, 2018

By J. Roger Loebenstein

Demand for arsenic trioxide exceeded supply in 1978 and 1979, and the major domestic and foreign producers allocated available supplies to customers. Major demand has been from the cotton-growing and wood-preserving industries. Ample supplies of arsenic metal produced in the United States and Sweden were available in 1978 and 1979. Major demand for metal was from the automobile battery industry in Japan, Europe, and the United States. Legislation and Government Programs.-The Occupational Safety and Health Administration (OSHA), promulgated the final standard on the occupational exposure to inorganic arsenic, effective August 1, 1978.2 The need for the standard was a result of OSHA's conclusion that inorganic arsenic is a human carcinogen. The purpose of the standard was to minimize the incidence of lung cancer among workers exposed to inorganic arsenic. The maximum exposure to arsenic was lowered from the previous ceiling of 500 micrograms per cubic meter of air to 10 micrograms per cubic meter over an 8-hour time period. OSHA had originally recommended a ceiling limit of 4 micrograms per cubic meter in January 1975. Provisions of the new standard require exposed employees to wear respirators and undergo continuous medical monitoring. Other provisions establish regulated areas limited to authorized employees and require the construction of special lunch-room and worker hygiene facilities and the posting of signs and labels warning of the presence of arsenic. The new arsenic standard will have a significant economic impact on copper, zinc, gold, and lead smelters as well as consumers of arsenic trioxide. A number of copper companies have joined together to contest the standard in court. However, measures to comply with the standard have been initiated by ASARCO Incorporated at its Tacoma, Wash. plant.

Jan 1, 1980

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 Philip D. Wilson

SPEED is essentiaI in this war program and it is hard to keep up with developments. When the title of this paper was chosen, the contemplated magnesium production for which plants were then under construction was some 200,000 tons of metal per year or sixty times the 3350-ton production in prewar 1939. A few- days later an analysis of the President's 185,000-plane pro-gram, incendiary bomb schedules, and the additional requirements of the Army. Navy and Maritime Commission made it apparent that a much greater amount of magnesium must be provided in 1943. The new figures are huge but the censor will not per-mit their disclosure.

Jan 1, 1942

By Charles G. Kemsley

MR. C. R. WHITTEMORE: It is interesting to note that the mining industry is making increased use of alloy steels for drilling. They will undoubtedly lead to greater footage at lesser cost. Mr. Kemsley states that, for use in hard ground, the shanks are brought to a hardness of 435 to 440 Brinell by heating them to approximately l,800°F. It seems to me that this temperature is excessively high-it is considerably above the critical point of the steel. The only effect of such a high temperature is to lessen considerably the impact resistance of the steel. The possibilities of an oil quench, followed by a tempering draw which does not lessen the hardness of the steel too much but increases its toughness, might well repay further study; also the temperature control, a factor which depends on the composition of the steel. However, service results are undoubtedly the best criterion of practice. MR. KEMSLEY: I would like to point out that the steel is not quenched at 1,800°F. After heating to this temperature, it is laid aside to cool gradually; this high temperature is necessary to produce the required hardness by simple normalizing-cooling in still air. We all know that ideal conditions for hardening steel demand salt baths and furnaces with automatic temperature control, but for most companies the cost of such equipment having sufficient output capacity is prohibitive. The end we are trying to attain is to make good drills at a cost that will be within the means of any mine.

Jan 1, 1942

By Y. Foucaud, C. Eswaraiah, L. Filippov

Enhanced gravity separators such as Falcon concentrator which uses additional centrifugal force, are the most common gravity concentration techniques used for fine particles processing. Hence, understanding the kinetics and separation mechanisms within these separators is of paramount interest. Recent research yielded a predictive physical model for the Falcon Ultra Fine (UF) which however does not explain some results obtained with industrial ores. This study aims to identify the mechanisms involved in Falcon UF separation with the objective of confirming or rejecting the hypotheses on which the current model is built and suggesting potential points of improvement. The Falcon UF kinetics is investigated through the processing of complex low-grade and fine-grained ores from the Altenberg tin deposit (Germany), the Tabuaço tungsten deposit (Portugal) as well as a synthetic iron ore. Saturation tests are performed on the Falcon UF by controlling the separation efficiency in terms of recovery and enrichment ratio with time or feed mass. Results show an evolution of Falcon UF performance with time in contradiction with the stationary separation hypothesis on which the physical model is based. Observation of the concentrate bed suggests the presence of erosion figures in furrows which may play locally an active role in the separation. In terms of Falcon UF separation timing, three phases can be distinguished. First, upon initial feeding of the bowl, a bed quickly grows unselectively and ultra-fine particles are ejected from the bowl until the bed reaches its final profile. Next, actual separation occurs with selective concentration of dense particles. Finally, capture sites saturate and recovery drops. The evolution of partition curves over time confirms the existence of two separation mechanisms. First, differential particles settling within the flowing film responsible for the ejection of small size particles during the whole separation cycle which is already accounted for in the physical model. The second mechanism involved may be explained by the action of lift force, neglected in the physical model, which acts preferentially on coarse particles deposited at the surface of the bed resulting in coarser particles being rejected in the tailings. Hence, the addition of a lift force component to the existing model is suggested to account for this second separation mechanism.

Jan 1, 2018

By H Jalalifar, N Aziz

In the ten years since the University of NSW proposed a pillar design methodology for bord and pillar operations, the Australian coal mining industry has changed substantially. What was primarily a bord and pillar design approach is now being applied to chain pillar design in longwall mines where the requirements are substantially different. The dimensions of chain pillars can impact on tailgate conditions (roof, rib and floor), seal performance, and surface subsidence. The status of chain pillar design practice in Australia is reviewed, with a focus on defining pillar strength, chain pillar loading, and assessing the performance of the roof/pillar/system. A new pillar strength equation is proposed for Australian coal that applies for all width/height ratios. An alternative analysis of probability of failure of chain pillars is presented.

Jan 1, 2005

By L. B. Rothfeld

In anticipation of RCRA reauthorization and subsequent rulemakings, the Bureau of Mines is studying potential economic impacts of RCRA on mining. For U.S. copper heap and dump leaching operations in a variety of terrains, the cost of liners and closure caps to comply with RCRA Subtitle D ranges from $55 million to $158 million per site, or about $500,000 per hectare ($200,000 per acre). If RCRA technology requirements and financial assurance had been required on current operations, 27 to 100% of production from heap and dump leaching would have been non-competitive at market prices between $2,310 and $1,650 per metric ton ($1.047 and $0.75 per pound) copper. This result is based on an analysis that considers return on capital, corporate overhead, marketing, and freight costs as well as operating and maintenance costs at the mine. Over the same price range, economic analysis using the IMPLAN input-output model on one-or two-county regions indicates potential net job losses of about 570 to 2,700 jobs. Total economic output of those counties could be reduced by about $180 million to $360 million.

Jan 1, 1994

By S. Chatterjee

Mining represents the first industry in the United States to have federally mandated training for its workers. Although the topics to be covered are specified in 30 CFR 48, course content is left to the discretion of the individual mine operators. Unfortunately, certain topics to be covered, such as prevention of accidents, are usually mine specific, making it very difficult to use the same course content in every mine. Further, training requirements may change from one mine to another, due to changes in the demographic characteristics of the workers, or changes in job and organizational characteristics. Therefore, if the intention of safety training is to modify the behavior of workers, it is expected that there should be some changes in the content of safety training programs in order to address the specific requirements of individual mines, or at least mines of similar worker and job characteristics. This study has been directed towards the development of a systems-based procedure for conducting a needs analysis. A special effort was made to understand the psychology of worker behavior by analyzing worker reactions to various organizational and job characteristics.

Jan 1, 1994