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By L. O. Bond

High costs--and high risks--are normal in coal exploration and mine development. But risks and ultimate costs are minimized by foreknowledge of prospective coal seams and adjacent formations. Extensive drill hole programs are often used to obtain needed information. Cores and cuttings from these holes are used to determine coal location, thickness, and quality; they are also used to study physical and geological characteristics of surrounding beds. Valuable as these core and cuttings studies are, their effectiveness is often diminished by loss of recovery or by incomplete analysis. Needed is an effective and economical method for augmenting these studies. Well logs provide information of the type needed for efficient cool prospecting. Furthermore, obtaining these logs in drill holes, and evaluating the data they provide, is both fast and economical. To investigate the usefulness of well logging methods in coal explorations, the authors worked with Mr. Jon Jenkins of Truax Truer Coal Company. Logs were run in a number of drill holes in various areas of the Illinois Basin; these areas provided variety both in coal quality and geologic conditions. The data were studied extensively using computer methods similar to those now used in the evaluation of oil and gas wells. (2, 3) This study was used to produce a computer-generated analysis designed especially for mining problems.

Jan 1, 1969

By R. J. Matetic, J. S. Peterson, P. G. Kovalchik

The National Institute for Occupational Safety and Health (NIOSH) has initiated a study of a roof bolter to reduce noise exposure to mine roof-bolter operators. An important segment of this research entails determining the affect of various drilling configurations on the performance (penetration rate) and sound power emissions when drilling into granite. Test conditions included using various combinations of rotational speeds and thrusts, using 2.54- and 3.49-mm- (1- and 1 3/8-in.-) diameter hexagonal and round drill steels, using vacuum and wet conditions and using drill media of differing compressive strengths. This paper details the affects of each of these variables on the performance and sound power level emission. When drilling into granite, it was found that wet drilling generated lower sound power levels and performed better than vacuum drilling.

PRESIDENT HERRES: Our ses¬sions this afternoon will be on safety. They will be under the direction of Mr. Dan Harrington, who has come here from Washington, D. C., particularly to preside at these meetings. I do not think Mr. Harrington needs any introduction to anyone present. He is a member of both the A. I. M. E., and the Rocky Mountain Coal Mining Institute, and has been for a great many years. The Rocky Mountain District is his old stamping ground. I take pleasure in turning the meeting over to Mr. Harrington. (Ap¬plause.) DAN HARRINGTON (Chief Engineer, Safety Division, U. S. Bureau of Mines, Washington, D. C.): Gentlemen, I suppose you have rather a long program, so there is no necessity for any introductory remarks. Inasmuch as I have rather a long-winded paper of my own, I presume the best thing I can do is to go ahead and read it. Mr. Herres asked me some time ago if I would preside here, and also have a paper, or at least have something to say to the Institute on safety. I thought it best to put whatever I had to say in written form, so I would know exactly what I had said and so I would be able to, if necessary, defend it later on.

Jan 1, 1929

By Frederick C. Trutt

Research performed on arcing faults and their interactions with electrical insulating materials within coal-mine power system enclosures are described. This work was performed at The Pennsylvania State University from December 1, 1976 through August 31, 1978. The thrust of this research has been divided into several primary areas. These include the development of a theoretical procedure for computation of three-phase and line-to-line arcing fault currents as a function of time, formulation of arc and tracking models so that arc voltages and energies may be computed, development of a simulation for pressure and temperature rises when a fault interacts with an electrical insulating material within an enclosure, experimental evaluation of electrical insulating materials in terms of their tendency to support and maintain an arc as well as their potential contribution to enclosure pressure rises, and integration of the above research areas to form overall procedures for theoretical and experimental evaluation. During the course of this research, consideration has been given to the possible effects? of an internal methane-air explosion within an enclosure as well as the potential influence of utilization-voltage-level, conductor spacings, and enclosure venting. Conclusions and recommendations address potential means for protection against enclosure failure, internal design considerations, and low-power testing procedures which might be used to evaluate insulating materials to be utilized within an enclosure.

Jan 1, 1978

By C. D. Anderson

A variety of processing technologies exist for recovery from both primary and secondary sources of rhenium. Currently, there are no known primary rhenium deposits, thus, the method in which primary rhenium is produced is dependent on the commodity of which it is a byproduct, e.g., copper, molybdenum, uranium, etc. In addition, focus on the recovery of rhenium from secondary sources, such as alloy scraps and catalysts, is continually growing. This paper presents a review of both primary and secondary processing technologies for the recovery of rhenium. Key Words: Rhenium, Ammonium Perrhenate, Extractive Metallurgy

Feb 27, 2013

GE Industrial Systems has received a multimillion dollar contract from Bucyrus International to supply complete electrical systems for three new draglines. These machines will be installed at Coal India’s Northern Coalfields’ Dudhichua and Nigahi open cast mines. The Dudhichua and Nigahi mines are located south of Varanasi. They produce Type C and Type E coal for use in the region’s super-thermal power stations. The GE systems will power and control the drag, hoist and swing motions of one Bucyrus W2000 walking dragline at Dudhichua and two a Nigahi.

Jan 1, 2000

Develop a new technique of in situ rock stress measurement which can be used when and where the conventional methods, such as the overcoring stress relief methods and the hydrofracturing method, cannot be effectively applied. Approach The Bureau of Mines developed basic principles to determine existing biaxial stresses in rock mass by using an instrumentation package consisting of one 3.8-cm-diameter hydraulic cylindrical pressure cell (CPC) and two 5.7-cm-diameter cement-capsulated flat hydraulic borehole pressure cells (BPC) to he installed in a single drill hole.

Jan 1, 1988

By Leonardo Flores

"Minera Escondida operates two open pits on a porphyry copper district, southeast of Antofagasta, Chile. During 2005, ore will be delivered exclusively from one pit to two concentrators, while from 2006 both pits will provide ore to these plants. Annual testing programmes on drillhole samples, have allowed for the construction of hardness block models since 2000. These models have delivered two main hardness descriptors, the Bond work index and the SAG power index. These parameters and plant operational specifications have been used as input information to forecast, the expected throughput and ball mill product size (P80) for each block of ore. Two forecasting techniques have been used, an in house model, strongly dependant of bond work index and MinnovEx´s CEET2, dependant of Bond work index and Sag power index and other parameters. Model performance has been evaluated from reconciliating on a monthly basis, the forecasted throughputs against a recalculated plant throughput which accounts for losses in tonnage not caused by ore hardness but instead by unscheduled plant operation problems. The model performance for 2003 was ± 2% yearly and ± 5% quarterly, well within the expected ± 3% and ± 10%. INTRODUCTIONThe Escondida porphyry copper district is located 140 km SE of Antofagasta, Chile at 3150 m.a.s.l, at 24°16’ South latitude and 69°04’ West longitude (figure 1)."

Jan 1, 2005

By Thomas Novak, Jeffrey L. Kohler, Joseph Sottile, Steve J. Gnapragasam

Modern underground coal mines can be very large, having a total connected load in excess of l5 000 hp. These mines generally have many miles of high-power conveyor belts and 15 or more miles of high-voltage power cables at distribution voltages of 12.47, 13.2, 13.8, or 14.4 kV. The shielded cables used in mine power distribution systems have a significant level of capacitance, on the order of 110 pF/ft. This level of capacitance, in an extensive power distribution system at today's voltage levels, can cause significant charging currents during a ground fault. This paper addresses the potential detrimental effects of capacitance charging currents during line-to-ground faults in mine power distribution systems. A representative mine power system is modeled, and simulations with faults at various locations are conducted to evaluate the effects of this capacitance on the level of fault current and relay selectivity. This paper also includes results of capacitance measurements made on mine power feeder cables used to validate the simulation model.

By J. B. Boisvert, D. S. Silva

"Drillhole placement involves benefits, costs, and constraints. Benefits are related to the drilling campaign value, which includes maximizing “indicated” and “measured” resources. Costs include drilling, rig movement, and access construction. Constraints include infeasible areas, maximum and minimum angles of drilling, maximum depth of drilling, and budget. Manually planning drillholes that meet these constraints is suboptimal. A framework for straight drillhole optimization that accounts for benefits, costs, and constraints is presented. The method aims to maximize the value of resources converted from “inferred” to indicated and measured. The framework is demonstrated for a Nevada gold deposit and outperforms manually selected drillholes.RÉSUMÉ Le choix de l’emplacement d’un trou de forage s’accompagne d’avantages, de coûts et de contraintes. Les avantages sont liés à la valeur d’une campagne de forage, qui comprend l’optimisation des ressources « indiquées » et « mesurées ». Les coûts englobent le forage, le déplacement de l’appareil de forage et la construction des routes d’accès. Quant aux contraintes, elles portent sur les zones impraticables, les angles maximums et minimums de forage, la profondeur maximale de forage ainsi que le budget. La planification manuelle des trous de forage répondant à ces contraintes est sous-optimale. Cet article présente un cadre relatif à l’optimisation des trous verticaux de forage tenant compte des avantages, des coûts et des contraintes. Cette méthode vise à optimiser la valeur des ressources converties de la phase « ressources présumées » à celle de « ressources indiquées et mesurées ». Ce cadre est appliqué à un gisement aurifère du Nevada et donne de meilleurs résultats que les trous de forage sélectionnés manuellement. INTRODUCTIONDetermining the optimum location of infill drilling has been studied because the high cost of drilling suggests that using fewer drillholes is preferred, and targeting locations of the deposit that are locally uncertain should result in better mine planning decisions and increased profit of the operation. Existing methods for optimizing drillhole locations consider minimizing the kriging variance (KV) as the objective and are mostly restricted to two dimensions (Soltani-Mohammadi & Hezarkhari, 2013a, b; Soltani- Mohammadi, Safa, & Mokhtari, 2016)."

Jan 1, 2018

By Philip W. Johnson, Charles D. Haynes

"Abstract - The coalbed methane industry has become a prominent source of domestic natural gas, with its technology having evolved over the past 30 years. Whereas most coalbed methane wells are able to produce without major interruption over their economic lives, wells operating in an underground mining area are subject to being mined-through. If mine-through occurs, the productivity of the well is at least compromised, and may even be terminated. The economic consequences of mine-through may be relatively simple if mineral ownership and extraction rights are common for the coal and coalbed methane. However, if ownership is not common and a superior coalbed methane lease exists, the coalbed methane ownership must be compensated for lost production caused by mine-through. This paper presents a relatively straightforward method to calculate the value of the lost production caused by the mine-through. It uses technology from mining and petroleum engineering, as well as simple economics and financial management techniques.Sommaire - L’industrie de la production de méthane houiller est aujourd’hui une source importante de gaz naturel domestique dont la technologie a considérablement évolué au cours des trente dernières années. Bien que la plupart des puits de méthane houiller peuvent être mis en production durant l’entièreté de leur vie utile sans interruption majeure, les puits implantés en périphérie de mines souterraines sont sujets à être recoupés par ces dernières. Un tel recoupement peut compromettre, ou même mettre fin à la production d'un tel puits. Les conséquences économiques du recoupement par une mine souterraine peuvent être relativement simples quand les droits miniers et les droits d’extraction sont détenus en commun pour le charbon et le méthane houiller. Si toutefois ces droits ne sont pas détenus en commun et qu’il y a eu octroi d’une concession de méthane houiller de qualité supérieure, les détenteurs du méthane houiller doivent être compensés pour la perte de production résultant du recoupement par une mine souterraine. Cet article présente une méthode relativement simple pour calculer la valeur des pertes de production suite au recoupement par une mine souterraine. Cette méthode fait appel aux technologies de l’industrie minière et pétrolière ainsi qu’à des techniques simples d’économie et de gestion financière."

Jan 1, 2006

By K Haga, G Danha, A Shibayama, L L. Godirilwe

The hydrometallurgical separation and enrichment processes provide an effective way to selectively recover metals from relatively dilute multicomponent sulfuric acid leach solutions. The multicomponent leach solution utilised in this study contained 0.3 g/L Cu, 0.34 g/L Ni, 0.13 g/L Co, and 2.96 g/L Fe, which was obtained after high-pressure oxidative acid leaching (HPOAL) of the copper-nickel smelter slag. The solvent extraction (SX), precipitation, and xanthate complexation processes were employed to recover and upgrade Cu, Ni, and Co from the leach solution. Batch SX tests were carried out using a countercurrent two-stage mixer settler extraction column, and LIX 984N (10 per cent v/v) as a copper extractant. Fundamental parameters influencing the extraction process such as pH, mixing speed, H2SO4 concentration, and organic/aqueous (O/A) phase ratio were investigated. For copper enrichment in solution, a combination of two extraction stages and two stripping stages were employed. Copper was successively separated from Fe, Ni, and Co under optimised extraction conditions (pH 2, 400 rev/min, O/A 0.25, and 20 min contacting) and stripping conditions (175 g/L H2SO4, 400 rev/min, O/A 4, and 20 min contacting). About 97 per cent of copper was extracted with low co-extraction of Fe, Ni, and Co of about 5.90 per cent, 1.47 per cent, and 2.53 per cent, correspondingly. A final Cu-rich solution containing 23 g/L Cu was obtained with a very low Fe concentration of 0.05 g/L. Additionally, for iron removal from the Ni/Co raffinate solution, more than 99 per cent of iron was precipitated at pH 4 by the addition of a calcium carbonate (CaCO3) suspension, with low co-precipitation of nickel and cobalt of around 3.68 per cent and 2.27 per cent, respectively. Furthermore, about 83.6 per cent of nickel and 99.4 per cent cobalt were co-precipitated from the solution by potassium amyl xanthate (PAX) solution at pH 6. The Ni and Co xanthate complexes were thermally decomposed and recovered as cobalt oxide (CoO) and nickel sulfide (NiS) solids.

Aug 24, 2022

By D Rattray, D Macfarlane, I Robb, N Halpin, G T. Dale

Mining faces many environmental, social and regulatory liabilities of which water management is just one. Others include site rehabilitation, carbon emissions, biodiversity offsets, strategic cropping land, subsidence, and noise and dust generation. Management of these liabilities is commonly seen as a cost of doing business and each is often independently addressed, bypassing the opportunity to reduce costs through integrated approaches. Furthermore, approaches to dealing with these liabilities tend to be constrained by a prevailing culture of engineered solutions and lack of appreciation of risk associated with alternative and hybrid alternative-engineered solutions. Suboptimal outcomes can also be reinforced by rigid regulatory constraints. While the cost of addressing operational liabilities may be a small proportion of overall mine management costs, failure to do so effectively may influence social licence to operate and, as recently demonstrated by the decision of the NSW Land and Environment Court to block expansion of the Warkworth Mine near Singleton, absolute licence to operate.Integration of environmental, social and regulatory liabilities with value-creating and risk-reduction opportunities such as beneficial water use, carbon bio-sequestration, habitat connectivity, keyline farming, improved grazing design and management systems, windbreaks and visual screens, presents opportunities to reduce risk and create value. This potential may achieve overall improved outcomes in both economic and non-economic mine performance criteria.Two case studies in beneficial use of waste water from the mining and coal seam gas (CSG) sectors (which operate under different legislation) will be used to illustrate the potential to address mine development, operational and closure liabilities by understanding opportunities to reduce risk and create value through a holistic water management framework. The technical requirements and alternative approaches to beneficial use of mine water are addressed, along with the direct economic benefits for mine operational costs and opportunities to positively engage communities and build resilience into social licence to operate. Regulatory barriers to achieving improved outcomes will be discussed.CITATION:Dale, G T, Robb, I, Halpin, N, Macfarlane, D and Rattray, D, 2013. Opportunities for integrated mine management to minimise risk and create value, in Proceedings Water in Mining 2013 , pp 227-234 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By S. Castro, L. Gutierrez

"Mining operations are often located in remote arid environments with limited access to fresh water. Shortage of fresh water in such cases makes it necessary to use seawater in mineral processing plants. Such plants treating Cu- Mo sulfide ores in seawater have been fully operational in Chile (e.g. Las Luces, Centinela). In many cases process waters used in commercial flotation plants (e.g. Mt Keith in Western Australia) are even more concentrated electrolyte solutions than seawater. This paper is an attempt at classification of the flotation operations carried out in process waters that are concentrated electrolyte solutions.INTRODUCTIONAccording to Gleick (1966), of the total Earth’ water resources 97.5% is in the oceans and ice caps, and thus only about 2.5% is fresh water. Shortage of fresh water in many parts of the world makes it necessary to use seawater in mineral processing operations. The existing commercial operations using seawater as well as recent research projects that deal not only with sulfide ores but also with apatite ores provide a lot of information that can now be generalized. The progress that has been made in this area is reviewed and based on this information an attempt is being made at classifying the flotation operations carried out in highly concentrated electrolyte process waters.SALT FLOTATIONFlotation in highly concentrated electrolyte solutions was studied by Klassen (Klassen, 1963). He reported that hydrophobic, bituminous coals, could float in salt solutions without addition of any other flotation agents. The process is referred to as salt flotation. Other inherently hyhrophobic minerals (e.g. talc, graphite, sulfur, etc.) were shown to behave similarly (Klassen and Mokrousov, 1963)As Figure 1 shows, some coals float quite well in solutions of Na2SO4, NaCl and NaNO3 (Klassen, 1963). While there are differences between the tested salts (explained by different foamabilities of these solutions) all the tests indicate that only bituminous coals float well in concentrated electrolyte solutions. 0.3 M solutions are quite sufficient to initiate a good and very fast flotation. If wettability of various coals is compared it becomes obvious that these well floating coals are very hydrophobic bituminous coals (Figure 2)."

Jan 1, 2018

By Cesar Carrasco

Mine reconciliation is the art and science of comparing predictions and real-world outcomes with the intent of revealing the true quality of performance of models, planning, mining, and mineral processing. When mine reconciliation is conducted in a systematic, transparent and sustainable way it can play a central role in the governance of Mineral Resource and Mineral Reserve (MRMR) estimation and reporting. The core processes of modelling, planning, mining, and processing need to be transparent to be able to demonstrate that MRMR are reliable predictors of mine performance and value. Transparency is also necessary for mine technical staff to generate meaningful analyses, conclusions, and business improvement actions that demonstrably maximise value for all stakeholders. Most mines have some form of mine reconciliation practice, however because there is no agreed industry standard, and because mine reconciliation is difficult for a variety of reasons, it is often unsustained and/or ineffective at delivering the required transparency of performance. To deliver true governance of MRMR and business value, mine reconciliation must be sustainable. There are two categories of issues that combine to make mine reconciliation extremely difficult to sustain, these are technical, and people related. Technical issues include defining standard terms, accurately tracking material flows, data availability/adequacy/quality, calculation of key performance indicators and tolerance limits, analysis, and interpretation of results, understanding limitations of modelling techniques, and defining appropriate actions that can deliver value. These technical challenges are non-trivial, however compounding these are a range of people issues that include personal agendas, scepticism, lack of knowledge and experience, poor teamwork, absent leadership, toxic workplace culture, staff turnover, ineffective communication, siloed organisational structure, and lack of deliberate change management. All these problems can be solved with clarity of purpose, definition of the process of mine reconciliation, discipline in following the process, appropriate resourcing, and commitment to success across the entire organisation. Outlined in this paper is a management system that delivers sustainable mine reconciliation by addressing both the technical and people issues described above. This approach can deliver significant value for a mine and adds a robust, defensible governance over MRMR estimation and reporting.

Oct 1, 2024

By Y. H. Cheng, D. M. Lewis, V. Castranova, M. W. Barger, J. K. H. Ma, J. Y. C. Ma, W. F. Xin

Bis-basic ethers off fluorene and fluoren-9-substituted derivatives such as tilorone have been reported to inhibit silica-induced fibrosis in rats. The potential antifibrotic potency of 2,7-bis (diethylamino) ethixy fluorine fluorenone (F-9-H.H), fluorenoxime (F-9-one), and fluorenol (F-9-ol) was F-9-axime > F-9-one ~ F-9-H,H > F-9-ol. Since the release of reactive oxygen species and growth factors from alveolar macrophages (AM) in response to silica exposure has been linked to the development of pulmonary fibrosis, the present study was carried out to determine the inhibitory effects of these compounds on rat AM activity in vitro. The following parameters were monitored: (1) cellular viability; (2) zymosan-induced respiratory burst activity (superoxide and hydrogen peroxide release, chemiluminescence, and oxygen consumption) of AM; (3) drug binding to AM; and (4) lipopolysaccharide (LPS)-stimulated interleukin- I (IL-1) release from AM. The bis-basic ethers, at 40 did not affect cell viability when incubated with AM for 30 min, but significantly inhibited zymosan-induced macrophage respiratory burst activity. The inhibitory effect of these agents was F-9-oxime > F-9-one ~F-9-H,H > F-9-ol. Binding of these drugs to AM was time and dose dependent, and exhibited the following binding affinity: F-9-oxime > F-9-one > F-9-H,H > F-9-ol. F-9- oxime was shown to inhibit LPS-stimulated IL-I release by AM in a dose-dependent manner. This inhibition of IL-1 release by AM cannot be explained as a decrease in viability. In addition, these drugs were also shown to impair human fibroblast proliferation in response to serum stimuli without impairing cell viability. These results indicate a positive correlation between drug binding to AM or other cell types and their inhibitory effects on cellular activities including oxygen consumption, superoxide release, hydrogen peroxide secretion, chemiluminescence, IL-I release, and proliferation. The ability of-these bis-basic ethers to modify AM and fibroblast functions in vitro suggests that further investigation of their reported antifibrotic potency in vivo is warranted.

Dec 1, 1996

By Z. Jin, D. DePaoli, P. Zhang

"Phosphogypsum is a byproduct created during the production of industrial wet-process phosphoric acid. This study focused on recovering rare earth elements (REEs) from a Florida phosphogypsum sample and investigated the effects of removing detrimental impurities such as phosphorus pentoxide (P2O5 ), uranium (U) and fluorine (F) during the leaching process. Experimental results indicated that REE leaching efficiency increased rapidly, reached a maximum and then began to decrease with sulfuric acid concentrations ranging from 0 to 10 percent and temperatures ranging from 20 to 70 °C. At a sulfuric acid concentration of 5 percent and leaching temperature of 50 °C, REE leaching efficiency obtained a maximum value of approximately 43 percent. Increasing the leaching time or liquid/solid ratio increased the leaching efficiency. The leaching efficiencies of P2O5, U and F consistently increased with sulfuric acid concentration, temperature, leaching time and liquid/solid ratio within the testing ranges. A fine-grain gypsum concentrate, sized smaller than 40 µm, was separated from leached phosphogypsum through elutriation, in which the P2O5, U and F content levels were reduced by 99, 70 and 83 percent, respectively, from their content levels in fresh phosphogypsum. IntroductionPhosphogypsum is a byproduct generated during the industrial wet process of phosphoric acid production, in which sulfuric acid is used to digest phosphate rock. Gypsum (CaSO4·2H2O), the main component of phosphogypsum, usually accounts for 65 to 95 percent of phosphogypsum by weight.There are small quantities of impurities in phosphogypsum, such as phosphates (H3PO4, Ca(H2PO4)2·H2O, CaHPO4·2H2O and Ca3(PO4)2), fluorides (NaF, Na2SiF6, Na3AlF6, Na3FeF6 and CaF), sulfates, trace metals and radioactive elements (Rutherford, Dudas and Arocena, 1996). Global phosphogypsum generation is estimated at 200 Mt/a (Parreira, Kobayashi and Silvestre, 2003; Yang et al., 2009), but only about 15 percent is recycled as building materials, agricultural fertilizers or soil stabilization amendments (Tayibi Choura and Lopez, 2009)."

Jan 1, 2017

By Kevin Ashley

Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate ?lter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (?rst) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air ?lter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards.

Jan 1, 2009

By J. Huh

Recently, there is growing trend to build the high-rise and install curtain walls. Following this trend, we developed robot for building wall cleaning work, which moves along Built-in guide rail of building. Because it moves attached at building wall for cleaning work, it can be seriously affected by potential threats, like earthquake, strong wind, malfunction, and construction error of built-in guide rail. In order to cope with those threats actively, this paper presents the Fail-Safety system. The building wall cleaning robot consists of two moving system: The Horizontal Moving System which mainly do maintenance work, and The Vertical Climbing System which transport the horizontal moving system floor by floor. We apply the Fail-Safety system to these systems. The Fail-Safety system consists of sensors to detect external situation, and, with information of sensors, give instruction for what to do. This robot system is installed with four kinds of sensors: shock sensor, infrared ray sensor, laser sensor, magnetic sensor. First, shock sensor detects external shock during cleaning work. When shock sensor detects big shock, the robot returns to starting point to inspect how damaged it is. Second, infrared ray sensor detects damage of built-in guide rail. It is to prevent destruction of robot caused by moving along damaged rail. Third, laser sensor gives notice about where obstacle is. It is for robot to avoid crash with obstacle and decrease damage. Fourth, magnetic sensor detects magnetic points, which are installed in rail at regular intervals, and helps robot to find its position, based on location of magnetic points detected. If robot is damaged by external shock and its encoder, which gives information of location to it, is not working, magnetic sensor will give information of robot?s location to robot. And then, robot regulates its velocity depending on position of it, and safely returns to starting point. The Fail-Safety system in this paper is for building wall cleaning robot to sense external threats, and prevent getting worse. Applied to this active protection system, making safe environment of maintenance work is possible for robot system.

Aug 1, 2013

By John W. Welty

Volcanic activity occurred during six periods of Arizona's geologic history. Precambrian volcanism occurred in two pulses at 1.8-1.6 billion years (b.y.) ago and at 1.2-1.1 b.y. ago. Volcanism occurred again in mid-Jurassic and Laramide (Late Cretaceousearly Tertiary) time. Volcanic rocks from these times are not used commercially in any significant quantity. Middle and late Cenozoic magmatic activity covered large areas of Arizona with voluminous volcanic rocks. During the mid-Tertiary magmatic pulse, explosive silicic magmatism, with eruption of areally extensive ash-flow tufts, covered large areas in the Basin and Range Province, while the Colorado Plateau remained largely unaffected. Basalt eruption also occurred during and immediately after silicic volcanism, leading to compositionally diverse suites of volcanic rocks. Late Cenozoic volcanism occurred throughout Arizona and was dominated by wide-spread eruption of basalt flows with local cinder-cone clusters and siliceous volcanic deposits. Perlite deposits near Picketpost Mountain in northeastern Pinal County account for the bulk of the industrial uses of mid-Cenozoic volcanic rocks. Other perlites of presumed middle Tertiary age are present in central, southeastern, and western Arizona, but to date remain unexploited. Arizona Fire Agate is a valuable gem material and is associated with volcanic rocks of middle Tertiary age. Basaltic rock of this age also is utilized in the manufacture of rock wool for insulation. Late Cenozoic volcanism produced most of the industrial-quality volcanic rocks. Basalt, cinder cones, and materials of rhyolitic composition are commercially exploited by municipal and Federal agencies and private industry for aggregates, road conditioners and maintenance materials, asphaltic concretes, cinder block construction, pozzolans, and landscaping. These deposits are generally confined to the Flagstaff and Springerville areas. A famous peridot gem locality is associated with late Tertiary basalts at Peridot Mesa on the San Carlos Indian Reservation. Important products derived from altered volcanic materials of late Cenozoic age include clay and zeolite. Arizona's volcanic-rock sequences are still incompletely known, particularly in central and western Arizona. The potential for recognition and exploitation of important new deposits of useful volcanic materials is high.

Jan 1, 1987