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By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"An electro-optical method was used to quantify superoxide (SO) release from single rat pulmonary alveolar macrophages (PAM) exposed in vitro to respirable quartz and kaolin dusts and in vivo to quartz. Release was determined by measuring the reduction of nitroblue tdrazolium (NBT) to a diformazan precipitate at 550 nm from video-recorded images of individual cells. In vitro exposure to 0.025 or 0.05 mg/ml kaolin for 40 minutes resulted in no significant differences in either the total diformazan produced (max) or the maximum rate of diformazan production (R)./n vitro exposure to 0.025 mg/ml c1uartz decreased max 38 percent while no significant change was found using 0.05 mg/ml. However, R was decreased 31 percent and 24 percent for the low and high dose, respectively. In contrast, PAM obtained from animals exposed in vivo to quartz dust for two or four weeks in inhalation chambers exhibited increased production of diformazan. However, only PAM analyzed three days post-exposure showed significant increases, while PAM from animals sacrificed ten or 31 days post-exposure were not significantly different from control. The combined in vitro and in vivo quartz results might suggest that there is an initital acute response to exposure that decreases the ability of PAM to produce SO, followed by recruitment of production of PAM with increased SO producing capability. It appears that removal of animals from the source of exposure permits PAM to return to control levels of SO production by31 days. Whether this would be true for chronic exposure remains to be elucidated.IntroductionPulmonary alveolar macrophages (PAM) protect the lungs by phagocytizing foreign debris and bacteria.(1) This process involves ingestion as well as destruction of foreign matter. Phagocytosis usually is accompanied by a respiratory burst which increases cellular oxygen consumption leading to the release of highly reactive oxygen metabolites.(2) These agents have been implicated in the killing of bacteria by phagocytes, but they have also been shown to be toxic and,have been linked to cancer, emphysema, arthritis, diabetes, and other diseases.(3) Toxic effects may be a result of 1) an abnormally low production of metabolites, resulting in damage to lung tissue by the respired bacteria and/or dusts; or 2) an abnormally high production resulting in direct damage to lung tissue by metabolites themselves."

Mar 1, 1989

By R. A. Williams

Electrical impedance tomographic methods have been applied to a variety of mineral and chemical processes in the laboratory and on plant. This review paper surveys technical developments in measurement methods to enable quantitative extraction of key process information in the form of mapping of concentration profiles, mixture homogeneity and suspension velocity. The methods for determining velocity are summarized, since this is of especial interest when applied to opaque systems where most conventional optically based measurements fail. A recent significant development is the use of ultra-high speed measurement that now allows velocity vectors to be extracted for fast moving mixtures and fluids (up to several metres per second). New data are reported pertinent to low and high solids concentration flow in pipelines. Use of the methods offer improvements to design of such systems but also points to the use of tomographic electrical sensor as online flow measurement and fault detection. This offers new opportunities for applications and benefits in the design and monitoring of mineral slurries and sludges.

Jan 1, 2008

By Maria Sullivan

There have been many papers and articles presented over the last 60 years questioning the relevance of the 8-millisecond blasting delay window as an ‘Industry rule of thumb’. The concept of using delays between blast holes to minimise vibration is well understood and agreed upon. The means for evaluating what that minimum delay interval needs to be, for a particular site given their ground conditions, design parameters and blasting techniques, is much less established. Some sites haven’t even recognised their required minimum delay value may not be 8-milliseconds!

Feb 6, 2023

By BHAMIDIPATI S. SASTRY, Pavan Kumar Kattamuri, ADITYA PANDEY

The thermal conductivity of rock surrounding the airway is one of the most important thermal properties for estimating strata heat transfer into the mine air and for designing the air-cooling strategies. Several laboratory methods are available for the determination of thermal conductivity; however, most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed for determining the temperature gradient of sandstone specimens while cooling and used for calculating thermal conductivity. The thermal conductivity of different sandstone specimens attains values between 2.37 and 2.59 W m− 1 °C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity, and porosity, along with thermal conductivity, are determined and highlighted in this study.

Jul 20, 2021

By BHAMIDIPATI S. SASTRY, KATTAMURI PAVAN KUMAR, ADITYA PANDEY

Several laboratory methods are available to determine the thermal conductivity of rocks, but most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus, which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed to determine the temperature gradient of sandstone specimens while cooling and is used to calculate thermal conductivity. The thermal conductivities of different sandstone specimens have values between 2.37 and 2.59 Wm−1°C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity and porosity, along with thermal conductivity, were determined and highlighted in this study.

By S. J. Buckler

Many chemical and metallurgical processes use submerged gas injection to increase contact area between gas and liquid phases in order to promote faster overall reaction or refining rates. The total interfacial area produced by gas injection through lances, nozzles or tuyeres is both an important design parameter for new vessels and a measurement for estimating the maximum processing capacity of existing equipment. Estimating total interfacial area from submerged injection into industrial pyrometallurgical vessels from existing knowledge is a problem with two aspects. The first difficulty is the difference in behaviour of cold (aqueous) and hot (molten metal) systems, implying that existing models and correlations of gas-liquid behaviour developed in low temperature systems are not necessarily appropriate for estimation of high temperature behaviour. The second difficulty is the issue of scale-up of correlations from laboratory to industrial sized vessels. The work presented in this paper is part of an ongoing experimental investigation, at the GK Williams CRC for Extractive Metallurgy, to quantify the total gas-liquid interfacial area available in pyrometallurgical vessels using chemical measurement methods. The effects of three operating variables, injected gas flow rate, nozzle diameter and nozzle submergence, on total interfacial area are quantified in a IOOL aqueous system - the first stage of a three stage process in examining the implications for scale-up of high temperature, medium-scale results are discussed. The results of work at high, injected gas flow rates (up to 500/min) show that the submerged Froude number is not sufficient for use as the sole variable in a predictive model of total interfacial area. Further work is being undertaken to identify other dimensionless variables that will better represent the gas-liquid characteristics in submerged injection that influence the formation of total interfacial area. The second and third stages of the experimental investigation involve measuring the total interfacial area in a large-scale (1000L) aqueous sodium sulphite and small-medium scale molten metal baths.

Jan 1, 2002

By H. Gumede

The occurrence of fracturing due to high stress levels is a major factor in hangingwall stability in deep level gold mine stopes. However, rock falls cannot be the result of these fractures alone. Rock falls can result only from the occurrence of unstable rock blocks defined by the interaction of the stress induced fractures and naturally occurring geological planes of weakness. These planes include bedding planes and joint set planes. However, there is a general lack of information on the characteristics of these planes (orientations, spacings and lengths)?it does not appear that any such systematic and quantified information, if collected, has been published. To remedy this situation to some extent, joint mapping exercises have been carried out in several geological environments in two gold mines. The data collected on joint geometry included orientation, spacing and length, and this information is included in the paper. In addition, the paper describes the use of the data collected to evaluate the potential for rock falls and the probability of failure of stope support

Jan 1, 2007

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

By I. Ward, E. Milosavljevic, M. Botz

"The silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide in leach solutions that contain primarily free cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method overestimates the concentration of free cyanide and underestimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric (MP) titration method for determining WAD cyanide that overcomes issues associated with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper, and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, analytical results obtained with the new MP-WAD method were found to be within about ±5% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.IntroductionThe silver nitrate titration method is widely used to estimate the concentration of cyanide in leach solution for purposes of cyanidation process control. Cyanide determined by silver nitrate titration is commonly referred to as “free” cyanide, but frequently should be referred to as “titratable” cyanide. By definition, free cyanide is the sum of the concentrations of aqueous hydrogen cyanide HCN(aq) and the cyanide anion CN- (ASTM, 2010). Titration will only yield a reasonably accurate measurement of free cyanide when metal-cyanide complex concentrations (e.g., cadmium, copper, mercury, nickel, silver and zinc) in solution are low. In other words, titration will only yield a reasonably accurate measurement of free cyanide if the solution primarily contains free cyanide."

Jan 1, 2015

By R L. Langak, R A. Heins

The use of differences in specific gravity between minerals to separate them has long been utilized in the extractive industries. The environmental and cost benefits of the commercialized forms of these processes are well understood and widely used. Gravity concentration is used inter alia in the primary beneficiation of gold, diamonds, coal, tin, ferrous metal ores and andalusite. The potential for economic loss due to poor performance of these gravity processes is significant, but diverse in manifestation and regular process monitoring can prevent or at least reduce these losses. The measurement of performance of gravity processes has always presented a challenge, due primarily to the masses of material involved and the physical nature of the processes, generally typified by long reporting time, and hazardous materials (such as Tetrabromoethane) for float and sink type tests. The development of density tracers has improved this situation, however recovery of these tracers from the process streams created the next set of challenges, requiring significant manpower to physically remove tracers from product dewatering screens. Additions to these tracers (magnetic or x-ray fluorescent) eased the recovery mechanism issues but made them much more expensive to produce, hence operators became concerned about losses during process testing. In addition, magnetic recovery of smaller size tracers by a magnet suspended above a loaded screen panel is still problematic. The development of new low cost magnetic tracers has improved statistical significance of tracer tests, as the tracers themselves can be bought and used in much larger quantities, whilst still remaining economically viable. Coupled with the development of effective magnetic recovery technology, such as the Gekko MagScreen, for even fine sized tracers, on-line, continuous tracer testing is now becoming a reality. Whilst the development of high technology radio frequency detection tracer systems continues, enabling the real time measurement of the process and interpretation of results, miniaturization and recovery of these tracers, which is critical given their costs at present, remains an issue. Keywords: Gravity, process measurement, tracers, magnetic recovery

Jan 1, 2006

By D J. Bradshaw

It is well known that the chemical environment determines the success of the flotation process, however its characterization and control is difficult to achieve. This work evaluates the use of various measurements, including mineral potential measurements, in gaining an understanding of the influence of varying parameters such as the milling media and the reagent suite composition on the flotation performance of a platinum group metal (PGM) bearing ore. The results showed differences in the response of the various mineral electrodes to the different conditions, however the changes in flotation performance of the different minerals in the ore could not be wholly described by the electrochemical changes, demonstrating the limitations of these measurements.

Jan 1, 1999

One of the earliest and continuing challenges in driving sustainable development in large scale resource industry projects is around the issue of assessment û how do you measure the sustainability of a mineral operation? One of the key road blocks when confronted with this challenge is the temptation of technical folks to reach for a definition of sustainability or sustainable development. But definitions, by definition, have boundaries and limitations that serve to constrain thinking û they limit the thinking of what we can achieve with sustainability (it also acts as a barrier that constrains innovation). Rather than seeking definitions, better understanding of the core perspectives around sustainability and their application to the minerals industry provides a much more powerful platform from which to conduct assessments. But it is only when these perspectives are combined with the right framework and supporting techniques that the complex becomes doable. With the support of the perspectives and the framework, various assessment and measurement methodologies can be used; the challenge is communicating to stakeholders the sustainability character of the project in ways that are meaningful and to which people can connect. Assessment is not about finding the best or most accurate methods that fulfil strictly academic and possibly abstract requirements. The challenge is to help people understand what the impacts are, and what the value contributions will be, in a format and language that make sense in their world-view.

Jan 1, 2009

By H. S. Chang

A three-dimension two-phase (air and dust) computer model was developed to model air velocity and respirable dust distributions in the longwall faces. This paper describes the derivation of the model including the model features, mathematical equations and boundary conditions. Example simulations were also performed for two longwall faces where measured respirable dust and air velocity distributions were available. The results indicated the model can simulate the mine conditions fairly accurately.

Jan 1, 1996

By J. Werfling, J. R. Kiehl

SUMMARY: The effects of blasting on structures are assessed on the basis of the maximum amplitudes of the occuring vibration velocities. If the standard values in the German Standard DIN 4150 are not exceeded, damages to structures are not to be expected. The estimation of the maximum vibration amplitudes is usually based on experience or on emperical formulae. However, a comparison of expected with measured values shows that these estimations are not conservative, particulary in case of small distances between blasting locations and structures. More reliable predictions are possible on the basis of numerical analyses, which simulate the three-dimensional propagation of waves with consideration of the geomechanical and geometrical conditions. In addition to the expected velocities, these analyses also allow the determination of stresses resulting from dynamic loading. If the dynamic stresses are known, the effects of blasting on structures can be predicted. ZUSAMMENFASSUNG: Die Auswirkungen sprengbedingter Erschütterungen auf bauliche Anlagen werden in der Praxis auf der Grundlage der Maximalamplituden der auftretenden Schwinggeschwindigkeiten beurteilt. In der DIN 4150 werden Anhaltswerte angegeben, bei deren Einhaltung Schäden von Gebäuden nicht zu erwarten sind. Die Abschätzung dieser Schwing-geschwindigkeiten erfolgt meist auf der Grundlage von Erfahrungswerten oder empirischer Formeln. Der Vergleich der prognostizierten Werte mit Meßergebnissen zeigt jedoch, daß diese Ansätze insbesondere dann, wenn die Abstände zwischen den Sprengorten und den Gebäuden gering sind, nicht konservativ sind. Zuverlässigere Prognosen sind auf der Grundlage von numerischen Berechnungen möglich, in denen die räumliche Ausbreitung von Erschütterungen unter Berücksichtigung der geomechanischen und geometrischen Verhältnisse simuliert wird. Mit derartigen Berechnungen können die zu erwartenden Schwinggeschwindigkeiten und die aus der dynamischen Beanspruchung resultierenden Spannungen ermittelt werden. Dies ermöglicht Aussagen über die Auswirkungen sprengbedingter Erschütterungen auf Bauwerke. RÉSUMÉ: Les conséquences de vibrations résultantes d'explosions pour des bâtiments sont estimés dans la pratique à partir des amplitudes maximales des vitesses d'oscillation. Dans la norme allemande DIN 4150 des valeurs d'orientation sont données, avec l'observation desquelles de dommage à des bâtiments n'est pas à présumer. Ces vitesses d'oscillation sont estimés généralement à partir de valeurs d'expérience ou de formules empiriques. La comparaison des valeurs prédits avec des résultats de mesures montre cependant que ces hypothèses ne sont pas conservateurs, en particulier si les distances entre les lieux de sautage et les bâtiments sont petites. Des prédictions plus fiables sont possibles à partir de calculs numériques, dans lesquelles la dissipation spatiale de vibrations est simulée en considération de la situation géoméchanique et géométrique. Avec tels calculs les vitesses de vibration à présumer et les contraintes résultantes de l'effort dynamique peuvent être établies. Cela permet de constater sur les conséquences de vibrations résultantes d'explosions pour des bâtiments.

Jan 1, 2003

By T van Niel, M Trefry, B Baker, I Rea, A Hawdon, D McJannet, D Boadle, R Fandrich, A Littleboy

Many open cut mines extend to depths well below the natural water table level with constant dewatering required to maintain operations. When mining activities cease the groundwater starts to fill the void and pit lakes form. The resultant pit lake is directly connected to the surrounding water table and understanding the hydrological and chemical evolution of these lakes is important for minimising environmental impacts. In Western Australia alone there are currently 1800 mine voids and more than 150 mines operating below the water table (Johnson and Wright, 2003). In conjunction with BHP Billiton Iron Ore, CSIRO has been undertaking research to measure and model rates of evaporation from pit lakes in the Pilbara region of Western Australia. Extreme high temperatures and low humidity ensures that this region experiences the highest evaporation rates in Australia.CITATION:McJannet, D, Hawdon, A, Boadle, D, Baker, B, van Neil, T, Littleboy, A, Trefry, M, Rea, I and Fandrich, R, 2016. Measurements and modelling of evaporation from abandoned mine pit lakes, in Proceedings Life-of-Mine 2016 Conference, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J. E. Johnson

Discussion of the paper of Mark A. Amnion, presented at the Cleveland meeting October, 1913, and printed in Bulletin No. 70, October, 1913, pp. 1167 to 1 79. J. E. JOHNSON, JR., Ashland, Wis.:-Mr. Amnion's paper is of great value and it is not with any desire to reflect. on it that I wish to make some comments on the use of the scleroscope. We obtained one on trial some months ago and made very extensive tests with it, but without getting very satisfactory results. The readings on good car-wheels and bad ones were just about the same, but the factor in its use most likely to produce erroneous results is a variation in the thickness of the specimen being tested. In order to find out something on this subject we cut a thin disk, about -1,: in. thick, off a brass rod; then one 0.25 in. thick, and another about 1 in. thick, put the surfaces of all in about the same condition and tested them with the scleroscope. The readings varied widely; the resilience of the anvil evidently entered to a very high degree on thin pieces. By putting a soft cushion between such a thin specimen and the anvil, and forcing it up against the tube, the softness of the cushion cut off the resilience of the anvil and the results were more like those of the thick specimens. After a thickness of 1 in. was passed, the specimen seemed to have mass enough so that the resilience of the anvil no longer played an important part, and above that thickness results on different materials would be comparable, even though the thicknesses differed. But in order to get comparable results on thin specimens the thickness of those being tested should be the same. I should like to ask how the variations introduced in this way were overcome, so as to get strictly comparable results. Mr. AMMON :-.I have not had much experience in that, but the scleroscope is simply an indication of the surface harden-

Dec 1, 1912

By Clifford C. Hanninen, Allan H. Caverson

Within the past nine years a means for measuring the distance between mine roof and floor was developed at the White Pine mine which yields relevant information utilized in the mining operation. The technique known as "convergence" is an efficient, low cost way for obtaining large quantities of data for predicting roof falls, caving activity and overall mine stability. Since 1964 the activity of convergence measurements has expanded to become a production tool found in all sections of the mine. The program involves four types of activity: 1) monthly measurements in areas known to be active and in sample blocks scattered throughout the mine for a long-term stability study; 2) semi- monthly measurements along vital travel roads, belt drifts and compressor sites; 3) weekly measurements in areas where men are working; 4) daily measurements in pillar-recovery and caving operations.

Jan 5, 1973

By M. Rufli

Until not so long ago most ring geared mills were operated with fix speed motors only. By using the latest generation of medium voltage frequency converters, new possibilities have arisen to improve the grinding process. Beside all the direct and indirect advantages, several dedicated functions have now been implemented for ring geared grinding mills in the minerals industry. The sophisticated operational functions ensure a smooth, safe and reliable operation with minimum stress for the mechanical equipment and therefore utmost availability of the mill. Several papers have already been presented concerning the benefits of using this state of the art technology for mill drives. Now this paper is focusing on the experiences gained with this kind of sophisticated ring geared mill drive system rather than only show and explains the operational benefit of the different functions. Several measurements of different operating conditions, starting, frozen charge remover, controlled roll back, backlash, etc., made on an installed and commissioned 2 x 5 MW dual pinion ring geared mill drive system will be shown and discussed. The accuracy of the load sharing between the two 5 MW motors during starting, normal operation and stopping will be demonstrated using real measurements from an operating system. Finally the inherent features of these drive systems are briefly discussed.

Jan 1, 2011

By Atta B. Yiadom, A. David Miller, Robert C. Kirby, Sean M. Todaro

"San Pablo Dam is a 170-foot (52-meter)-high earthfill embankment, located approximately 10 miles (16 kilometers) north of downtown Oakland, California, that impounds a 38,600 acre-feet (47.6 million m3) reservoir for customers in the East Bay Municipal Utility District's (EBMUD's) service area. Seismic upgrades were designed and constructed in 2008 through 2010. Work included removal of an existing 140,000 cubic-yard (107,000 m3) downstream buttress, which was replaced with an enlarged 300,000 cubic-yard (230,000 m3) buttress founded on alluvium and colluvium that were improved in-place using Cement Deep Soil Mixing (CDSM) technology. The site characterization for the project, design of CDSM, reuse of CDSM spoils as construction materials, and environmental permitting have been described in five previously published professional papers.This paper provides a brief summary of the design of the seismic upgrades and presents the results of measurements made during and/or after construction including the variation of CDSM strengths with time, piezometric levels within the dam and foundation soils, and seepage flow rates. These measured values are compared to the values estimated during design of the seismic upgrades.INTRODUCTIONSan Pablo Reservoir is located approximately 10 miles (16 kilometers) north of downtown Oakland, California, as shown in Fig 1. As many as 50 million gallons (200,000 m3) per day pass through the reservoir for treatment and distribution to a portion of the 1.3 million customers served by EBMUD. The dam is founded mainly on alluvium and was originally built in 1920 using materials excavated from the left and right abutments consisting of siltstone, claystone, fine-grained sandstone, mudstone, and shale that were excavated and placed using hydraulic fill methods. The dam is located within two miles (three kilometers) of the Hayward Fault which is capable of a moment magnitude 7.25 earthquake.Because of the foundation materials, construction method, and proximity to the Hayward Fault, the dam has undergone a series of seismic improvements, including the placement of a downstream compacted earth buttress in 1967 and an upstream compacted earth buttress in 1979. In 2002, the State of California Division of Safety of Dams (DSOD) requested that EBMUD evaluate the seismic stability of San Pablo Dam, following the results of a study that same year that indicated a 62 percent chance of a greater than 6.7 magnitude earthquake striking the San Francisco Bay region between 2003 and 2032. The dam was evaluated and it was concluded that portions of the underlying foundation soils may liquefy during the maximum credible earthquake which could cause the dam to become unstable."

Jan 1, 2015

By A. P. Bois, K. Saleh, A. Ghorbal, V. Hajiabdolmajid, G. Ballivy

"The knowledge of the initial stress field is not always sufficient to ensure the stability of mining stopes due to the high-stress variations generated by mining. Monitoring of these openings is then necessary and can provide quantitative information (deformations and stress variations) as well as qualitative information (state of stability).An applied technique for following the variations of stress and deformation in static and dynamic conditions, in relation to the evaluation of the stability of underground openings known as “Cylindre Instrumenté de l’Université de Sherbrooke” (CIUS) is discussed in this paper. In addition, a data acquisition system combined with a rock failure warning system has been developed to be connected to the CIUS for detecting the instabilities, which can endanger the stability of underground openings. Also, the installation of six CIUS and a data acquisition system as well as the selected procedure of programming in a warning system are briefly described."

Jan 1, 2003