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By L. R. Burdick

The Smokescope is an instrument recently developed for determining the density of smoke by shade comparison. The instrument is designed so that the smoke is seen adjacent to two shades of gray corresponding to Nos. 2 and 3 on the Ringelmann chart. Data on smoke density are important in the smoke-abatement field. The method that is specified and accepted as standard for smoke-density determination by the majority of city smoke regulations involves comparing the smoke shade with the four shades on the Ringelmann chart as published by the Bureau of Mines.2/ This investigation was made to determine the accuracy and convenience of the Smokescope. It was conducted as a part of the Bureau I s air-pollution work, which includes the study of techniques that will promote smoke abatement. The accuracy of the Smokescope was arbitrarily defined as the difference between the Smokescope determinations and the determinations by the accepted, standard method and was expressed as Smokescope correction. Although the corrections obtained were strictly correct only for the two observers and the Smokescope of the investigation, they indicate what might be expected from any observer who uses a Smokescope with reference shades that duplicate those of the test instrument. The report is devoted largely to the data on Smokescope correction, which were taken from a single stack under controlled smoke conditions. Field work, which was done at various locations with different stacks, is mentioned briefly in connection with the comparison of the convenience of the two methods. The data for estimating Smokescope correction were taken for the three variables that were expected to affect the results, namely, the density of the smoke, the amount of light, and the color of the sky behind the smoke.

Jan 1, 1955

By C. A. Pickles, S. J. Splinter, J. Cameron

The addition of copper oxide to a borosilicate slag resulted in the breakdown of the silicate network and a dramatic decrease in viscosity. With increasing borax to silica ratio the viscosity was reduced by two mechanisms. First, rising sodium oxide content promoted cleavage of the Si-O bonds. Second, increasing boric oxide (B2O3) content increased the number of trigonal borate units that were converted to tetrahedral borate units by sodium oxide and copper oxide. The BO4(4-) tetrahedra decreased the local silicate symmetry, thus disrupting the silicate network and lowering the viscosity. The activation energy decreased with increasing temperature and increasing copper oxide content

Jun 13, 1905

By J E. Everett

Ore selection is generally a highly subjective task, with emphasis on producing product with a consistent target grade matching a perceived market requirement. A composite selection criterion ‘Comp’ (a linear function of the grade vector) can be used to maximise ore tonnage at a specified target grade (in Fe and contaminants) extractable from a block model. The blocks correspond to the selective mining units, with grades interpolated from diamond drill hole data. An iterative procedure has been developed to identify the coefficients and cut-off value for the composite function ‘Comp’, maximising potential ore tonnage at target grade.Commonly, target grade is predetermined by marketing; however, there is no guarantee that maximising ore tonnage at a specified target grade maximises the potential value of the mine. If the value of ore could be expressed as a linear function of the grade components, then these coefficients would be appropriate for the selection criterion ‘Comp’. The cut-off value for ‘Comp’ would correspond to the marginal cost of production; all blocks with a ‘Comp’ score above the cut-off would be classified as ore; and the cumulative grade of these ore blocks would be the average product grade over the life of the mine.Unfortunately, no such value function for iron ore is generally available. Methods for estimating the value function are discussed, using the spot price and sensitivities based either upon operational tolerances for Fe and the contaminants or upon published price differentials. This approach has been applied to an anonymous Pilbara deposit with about one million blocks averaging 1.1 kt. It is shown how the optimal target grade, cut-off grade and maximum tonnage can all be explored as a function of marginal cost and iron ore price. Alternatively, given marginal cost and an iron ore price, the effects of changing the tolerances (and therefore the relative costs of the contaminants) can also be explored.It is suggested this procedure can enable informed decision-making for an iron ore mine. Rather than setting final policy for the entire life-of-mine, the method enables target grades and tonnage estimates to be revised by re-computation as the mine life proceeds to recognise changes in market conditions and knowledge about the resource.It should be emphasised that this paper is concerned with ore selection rather than ore sequencing. Appropriate ore selection is a necessary but not sufficient condition for maximising value. Having identified the set of blocks that potentially maximise value, the sequence in which they are mined will present a trade-off between producing at constant grade and extracting high value ore early. The sequencing issue is not considered here. It is shown that optimum ore selection for an open pit mine is independent of any consideration of discount rates, although ore sequencing will depend upon the time value of money if the product grade is to vary across time.CITATION:Everett, J E, 2015. Ore selection to maximise value, in Proceedings Iron Ore 2015, pp 443–448 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

A case study of a systematic approach to grinding circuit steady-state optimization is presented. After overall review of the flowsheet, two circuits were prepared for detailed testing. Functional performance analysis was chosen as the primary modelling system, and on this basis a quality assurance program for data gathering was implemented. A number of circuit design and operating variables were experimented with statistical analysis of plant test results revealed relationships previously unquantifiable by any other modelling technique. Improvements in classification system and mill grinding efficiencies were demonstrated and significant energy cost savings thus realized.

Jan 1, 1998

By H. J. McQueen

The modeling of the extrusion of 6061 alloy and its composites with 10 to 20 vol% Al203 or SiC by two techniques. The uniaxial finite element method FEM (DEFORM" ) provided force-stroke curves and temperature rise over the range 450-500 °C, 2.6-5mm/s and extrusion ratios of 31 and 64. The traditional technique considers ideal work and redundant work as well as friction and uses average temperatures and strain rates. The two techniques are used to clarify each other and to extend the analysis to 400 and 350 °C. The calculated efficiencies are compared to measured values in extrusion trials and to values derived for 7075 extrusion analyses. The analyses are based on constitutive equations determined by torsion testing tests.

Jan 1, 2004

By Deming Wang, R. A. Overfelt

"This paper presents a computer-aided heat transfer simulation method to predict the thermal characteristics of an alloy sample in a special furnace for directional solidification. A two-dimensional transient heat transfer by conduction combined with radiation is developed to calculate the energy exchange between a directional solidification furnace and the sample. Finite difference equations with control volumes are used to calculate the transient heat transfer. A special boundary control volume is used to combine heat conduction and radiation in the transient heat transfer. Heat radiation effects on the surfaces of the special control volumes with a changeable view factor during directional solidification processing are also represented. The simulation results are verified by measurable experimental data. Using the computer simulation model, many thermal properties of the directional solidified castings can be obtained, such as temperature distribution, solidification velocity, the shapes and positions of the liquid/solid interface and thermal gradient at the interfaces. These are very important to analyze microstructure of casting alloys, avoid casting defects and control casting quality. 1 IntroductionIn directional solidification (DS) processing of castings, the temperature distribution, the interface between liquid and solid zone, thermal gradient in the mushy (pasty) zone and solidification rates are very important factors to analyze the microstructure and the casting quality. These variables affect the orientation and size of dendrites, shapes of grains, solute segregation and deleterious casting defects, such as microporosity, freckles and segregation channels. In order to avoid the casting defects, the temperature distribution and thermal gradients of castings during directional solidification must be strictly controlled. However, the structure of furnaces used for directional solidification is often complex. Heat transfer and temperature distribution within a casting not only depend on furnace temperature but also on the thermal properties of the casting alloy, crucibles, retorts etc. A more accurate heat transfer analysis."

Jan 1, 2001

By Vinod K. Sikka, René Cooper

"Cohoes, New York 12047 Intermetallics are an attractive class of advanced materials. The aluminide intermetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other intermetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (1) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intelmetallics into the forefront of research and their commercial applications. This paper has described a method for melting Ni3AI-based alloys that successfully utilize the exotherrn for the formation of NiAl from the elemental materials. The reaction-synthesis method has also been utilized for the production of NiAI and NiAI-based alloy powders from the elemental powders. The reaction-synthesized powders of NiAI and NiAI-based alloys were consolidated by hot extrusion and evaluated for tensile properties over a temperature range from room temperature to 1050ºC. The powder-processing conditions have been found to have more influence on the ductile-to-brittle transition temperature of NiAI than the powder-production method.IntroductionIntermetallics are an attractive class of advanced materials [1-11]. The alum in ide interrnetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other interrnetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (I) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intermetallics into the forefront of research and their commercial applications. The paper will briefly review the processing techniques being pursued for the commercial applications of Ni3Al-based intermetallics. The major emphasis of the paper will deal with synthesis of Ni3Al and NiAI intelmetallics."

Jan 1, 1994

By P Myers, T Elkington, S Wonday

Sierra Rutile LimitedÆs (SRL) heavy mineral sand mining operation in Sierra Leone, West Africa, is embarking on a new phase of its life. After confronting many challenges during the 1990s and 2000s, SRL is embarking on a strategy of growth to recover maximum value from the mine over the rest of its life. Sophisticated linear programming techniques have been used to develop an optimum strategy for extracting SRLÆs many known deposits of economic grade, while considering options for expansion and for a variety of mining and processing methods and combinations. CITATION:Myers, P, Elkington, T and Wonday, S, 2012. Strategic optimisation at Sierra Rutile - A case study in maximising project value, in Proceedings Project Evaluation 2012 , pp 59-66 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By Carl Belser

In 1925 the Park Utah Consolidated Mines Co., after several years of experimental work, installed a system for signalling from cages which has been operating efficiently and with low upkeep costs for the post 19 years. The system was adopted for a large western metal mine but was later abandoned be arse of the constantly shifting shaft alinement. Recently the system has been studied and probably will be put into service at two other large mines. One of the principal reasons wry the system has not boon adopted more widely has been the lack of adequate details both as to the desirability of having such a system and as to its construction and operation. Previous signaling, systems contained undesirable features, such as charged bare wires extending the full length of the shaft. Under the direction of O. N. Friendly, then general superintendent of the Judge Mining & Smelting Co., the present system, entailing the use of a samll current at low voltage, was gradually developed. Many of the refinements in the system wore contributed by Leonard Wilson, consulting electrical engineer, Salt Lake City, Utah.

Jan 1, 1945

By S. Liu

With the development of global economy, the demand of mineral?s quantity and quality are in-creased, valuable minerals are more and more finer and poorer, and the capacity of concentration plant are more and more high. Using large-scale flotation cells can obviously enhance the capacity of treating the mineral, reduce the cost, and increase the economic benefit and competitive ability for the enterprise. BGRIMM advanced advisable technical scheme with optimally parameter and route for the feature of dynamic in large scale flotation machine, and developed the KYF Large Scale Flotation Cells, which have used more than 400. The paper advanced the history, the design principle, the operating principle, the structure feature and the application of KYF flotation ma-chine.

Jan 1, 2014

By A. A. Berk

In the course of a study of the formation of external deposits on tubes in water-tube boilers it became desirable to determine the sulfur dioxide (SO2) and sulfur trioxide (SO3) in the Due gases. Determinations made by the A.S.M.E. method for SO2 and SO3 in gaseous products of combustion did not give accurate results. It was found that minute quantities of copper, present in the flue gases from the coal in use, caused oxidation of sulfite in the absorption bottle and that the carbon dioxide (CO2) in the flue gases caused high values for SO2. The A.S.M.E. test procedure was revised to prevent oxidation of sulfite in the absorption bottle and to allow for the effect of CO2; subsequent analyses of flue gases produced reliable results. The revised procedure is described.

Jan 1, 1950

By A Holmgren, W Forsling

In the present study infrared attenuated total reflection (IR-ATR) was used to monitor the rate of in situ adsorption of heptyl xanthate on a layer of zinc sulfide synthesised on a germanium ATR crystal. The zinc sulfide surface was characterised using x-ray photoelectron spectroscopy (XPS). The absorbance of heptyl xanthate measured increased with increasing bulk concentration of the adsorbate up to an equilibrium plateau value corresponding to a fractional coverage of the surface sites of the substrate. For the adsorption from solutions of concentrations between 10-3 and 10-5 M, the rate of adsorption increased with increasing bulk concentration. At higher concentrations the measured absorbance should be corrected for the absorbance due to the concentration of xanthate in bulk solution. The present work provides a discussion of this correction. Assuming the adsorption stage to be rate-controlling and proportional both to the concentration of the adsorbing species in solution and unreacted surface area, a rate law governing this type of transient adsorption kinetics was derived. By means of absorbance data for the concentrations 0.1 and 0.01 mM, the rate constant of adsorption was calculated. From the initial part of a Langmuir adsorption isotherm, the absorbance at monolayer coverage and the equilibrium constant of adsorption could be estimated.

Jan 1, 2005

By D. Tahija

"Hecla's Greens Creek silver-gold-lead-zinc mill began using carbon dioxide rather than sulphuric acid to control pH in April, 2015. High pH levels in the grinding and lead flotation circuits are caused by the presence of re-mined cemented paste backfill in mill feed and need to be lowered to achieve good flotation response. Carbon dioxide has proven to be quite effective at controlling pH in the lead circuit with greatly improved pH target attainment. The allowable amount of carbon dioxide used is not limited by effects on lead-zinc selectivity and by poor froth characteristics, as was the case with sulphuric acid. Startup and implementation went smoothly, with few operational issues needing to be resolved. Early results from implementation of the system and its effects on mill performance will be presented. INTRODUCTION Hecla Greens Creek is a silver-gold-lead-zinc mine producing flotation lead and zinc concentrates, as well as a gravity gold concentrate. Besides their base metal contents, both the lead and zinc concentrates carry precious metals. The circuit is largely conventional, with SAG and ball mill grinding being followed by graphite removal preflotation, then conventional lead flotation and conventional zinc flotation. Both rougher concentrates are treated in regrind steps, followed by cleaner flotation. The cleaners tails are treated in an unorthodox bulk circuit to produce a low-grade zinc-lead concentrate marketed to Imperial Process smelters (1). BACKGROUND Backfill and Flotation pH The Greens Creek mine is an underground operation in which mined areas, after ore extraction, are backfilled, using rammed paste or pumped slurry. The backfill consists of mill tailings to which approximately five percent Portland or similar cement is added to enhance its compressive strength. Later mining near backfilled areas inevitably results in a considerable amount of old backfill being mixed with new ore before being shipped to the mill. Depending on orebody geometry, mining methods etc., the amount of backfill in mill feed is often 20% to 25% and sometimes even higher. Commercial cement, and consequently backfill prepared using it, contains excess lime. Because of this, backfill in mill feed is indistinguishable from the addition of a large amount of lime, so mill natural pHs often range above 10 or even 11. Similar situations have been recognized for many years at mines throughout the world (2)."

Jan 1, 2016

By V. A. Vorob'ev, A. N. Larionov, E. N. Ivanov, M. A. Ryazanov

The aim of the research is to increase the recoverable value of poor, difficult-to-digest complex mineral raw materials. In the Republic Belarus, universal centrifugal-shock devices have been created for crushing, grinding and classification of ore and non-metallic mineral raw materials in dry mode, which differ from foreign analogues by a higher level of resource saving (including electricity and materials). Dry-ore preparation technologies have been tested on a pilot scale: fine crushing (replacing grinding in rod mills), grinding (replacing wet grinding in ball mills) and pneumoclassification on different types of ores, - which made it possible to identify the criteria for the suitability and unsuitability of mineral raw materials for their use. The possibility of regulating the upper and lower limit of the size of the finished material is established, the possibility of reducing the yield of slimes (-0,020 mm) to 5 times is determined. A comparative analysis of the contrast degree of separation characteristics of ore a similar granulometric composition, crushed in wet and dry conditions, is performed. The achieved contrast degree of gravity properties after dry grinding - 104,3; after the wet - 60.2. When enriching on a centrifugal concentrator, gold recovery to the concentrate after dry grinding increased by 13.12% while improving the quality of the concentrate from 78.3 g/t gold to 90.75 g/t. When testing the gravity-flotation scheme for the enrichment of poor gold-quartz ore, the increment of gold extraction after dry grinding was 7.6% for gravity and 9.5% for flotation; the total increase in extraction is 17.1%. The possibility of flotation of a larger material after dry grinding has been proved, with an extraction gain of 1.5% compared to the flotation of thinner material after ball milling. The influence of dry technology on the efficiency of the leaching of gold and silver (an extraction gain of 5.5 to 10%) and heap leaching (extraction gain - up to 18.3%) was studied. The positive influence of dry ore preparation technologies on the efficiency of gold and silver heap leaching and heap leaching, thickening and filtration is proved. Lines of dry ore preparation technologies can be used in modular complexes for processing technogenic raw materials.

Jan 1, 2018

Jan 1, 1884

By F. A. Schinner

The present study has investigated the leachability of cadmium sulfide minerals by Thiobacillus ferrooxidans and the electrochemical reactions involved in the process. Using a cyclic voltammetric technic and carbon-paste-CdS electrodes, it was found that the bio-oxidation of semiconductor cadmium sulfide minerals consisted of a number of intermediate electrochemical reactions. The overall reaction was found to be controlled by solid state diffusion as suggested by the chrono-amperometric and chrono-potentiometric measurements. The activation energy of solid state diffusion was determined by the Sand's method to be AE=24.3 kJ. A generalized mechanism was proposed for the bacterial oxidation of cadmium sulfide by T. ferrooxidan and an explanation given for the importance of high redox potential of leach solution versus the decomposition potential of the sulfide mineral. Furthermore, the effects of n-type or p-type character of CdS substrates relative to their bioleachability was discussed.

Jan 1, 1993

By J. A. Madonna

Universities and colleges in three countries, Australia, Canada and the United States, recognized the need to establish and/or reorganize geoscience programs at the vocational and two-year technical levels. To accomplish this goal, a cooperative study with industry in one state or province from each country was initiated. These include 1) Tasmania, Australia, 2) British Columbia, Canada and 3) Alaska, United States. Over one hundred mineral industry organizations cooperated in the study by providing information regarding their specific training needs for support personnel. The data gathered has been used to identify training areas for semi-skilled, skilled and technical personnel in geochemical mineral exploration, including, but not limited to, geological skills, geochemical skills, environmental skills and computer skills. With the areas of major educational need defined for geochemical exploration, an educational field skills model has been developed for the three levels of training. The depth of each level of education and the training objectives for the work force at each level will be discussed.

Jan 1, 1993

By T. J. White

Xtaltite is the trade name for a generic technology which exploits the well known insolubility of some minerals, which naturally incorporate toxic waste elements, to consolidate and immobilise a range of inorganic waste products. It is a specific case of synthetic mineral immobilisation technology (SMITE) which is already used to immobilise high level nuclear wastes (HLW. Although HLW is highly toxic, it exists in relatively small volumes, occurs in central facilities and may be stabilised at low waste loading (< 10 wt%). In contrast, heavy metal wastes are of considerable volume, therefore Xtalitite waste forms must routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and be suitable for fabrication in remote locations using relatively simple technology. This paper details the methodology underlying Xtaltite, with particular emphasis given to the interplay between solid state chemistry, durability and economic considerations. Specific reference is made to the treatment of arsenious and mercurial wastes.

Jan 1, 1994

By R Price, B H. Miller

"The rise of autonomous haul truck fleets may have been initially driven by the rapid escalation of the cost of equipment operators, but the actual improvements reported by the major iron ore miners far exceeds the simple reduction in workforce. Utilising cost models developed for feasibility studies and mining contract modelling, the limits of cost improvements due to simple labour reductions are compared to those achieved by the early autonomous fleet adopters and through traditional process improvement techniques such as fleet class upgrades or hot-seating of equipment. As autonomous fleet implementation matures, it is likely that the gains seen by current adopters will seem minor compared to the limits generally governed by the limit of equipment utilisation. This ultimate limit is explored through time utilisation models, which were also developed for use in feasibility studies and mining contract modelling.Citation:Miller, B H and Price, R, 2016. Autonomous Haul System Savings - It's Not about Less Truckies but Better Truckies!, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 2–10 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Georgene Renner, Chee Theng, William Gleason

"With more than 900 booth spaces sold and 630 exhibiting companies displaying their wares, there was something for all 7,804 attendees on the exhibit floor of the 2015 SME Annual Conference & Expo in Denver, CO Feb. 15-18. The following is a sample of what was offered at the 2015 meeting.3D Laser MappingData collection and data analysis are changing how mining is done. One field in which technological advancements have made safer and more efficient operations possible is through site and slope monitoring.3D Laser Mapping, a United Kingdom-based company, was on hand at the 2015 SME Annual Conference and Expo to display its solutions for the mining industry, including its SiteMonitor4D system.The state-of-the-art laser measurementbased system was developed in partnership with geotechnical engineers and mining surveyors, and is a simple-to-use, reliable solution that has the flexibility and performance to function in a range of monitoring applications.The system measures and monitors the stability of rock faces, landslips and man-made structures, including ongoing, periodic measurement of volumes - stockpiles, cutbacks and waste dumps and has high-speed laser scanning for regular mapping of large areas by mounting the scanner on a vehicle.With specifications that other monitoring techniques cannot achieve, laser scanning opens up a new dimension in mine measurement and monitoring.www.sitemonitorsystems.comA.R. Wilfley and Sons Inc.Founded in 1919, A.R. Wilfley and Sons Inc. has been manufacturing dynamic-seal and static-seal pumps in Colorado for nearly 100 years, delivering its high-reliability, low-maintenance, heavy-duty process pumps and slurry pumps to the global mining industry. The family-owned company is now in the hands of the fifth generation."We are the dynamic-seal experts," regional sales manager Cesar Murillo said. "Most other companies are unable to do 100 percent dynamic seals and have to use mechanical seals or packing," he said, but Wilfley’s sealing technology does away with the need for mechanical seals and packing and their associated problems. As a result, solids and slurry handling capabilities are high, the pump can be run dry, and product dilution is eliminated. The pump can tolerate more misalignment, more cavitation, and more vibration in the pump during operation."

Jan 1, 2014