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By H. Utsunomiya, J. Su, K. S. Tamimi, S. Yue, M. Sanjari, L. Kestens, A. S. Kabir, R. Petrov

The recrystallization and texture evolution of AZ31 sheets obtained through two stages was investigated at different stages of post-rolling annealing. The specimens were rolled at the temperature of 100? and at a fast speed of 1000m/min and low speed of 15m/min with a reduction of 30% in one pass. The results show thatAZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The high speed and heavily deformed materials are fully recrystallized even at 100 °C.

Jan 1, 2015

By George Mylonakis

The curvatures and subsequent bending imposed to piles by the surrounding soil during the passage of strong seismic waves is studied. This type of bending develops even in the absence of a superstructure and is referred to as "kinematic bending", to distinguish it from bending imposed to piles by loads generated from the inertia of the superstructure ("inertial bending"). Although kinematic loading may be severe in the presence of sharp stiffness discontinuities in the profile and may lead to damage, it has received little attention by engineers. The scope of the paper is twofold: (i) to discuss some fundamental aspects of seismic pile bending, and (ii) to review some existing design methods. To this end, a dimensionless bending strain parameter (instead of the more commonly used bending moment), and a strain transmissibility function relating pile bending strain and corresponding soil shear strain are introduced. Numerical examples are also presented.

Jan 1, 2002

By W. D. Robson

THE prevention of silicosis by metallic aluminium has been reported by Denny, Robson, and Irwin in two papers. The first (1) was published in 1937; the second (2), in 1939. The results definitely established that silicosis was prevented in animals by the inhalation of small quantities of aluminium. The present communication records subsequent progress in this field of research. HARMLESSNESS OF ALUMINIUM Animal experiments having served their purpose, it became necessary to consider means to test the discovery on humans. A question for immediate consideration was: Is aluminium harmful to man when inhaled as a fine powder? While the animal experiments were reassuring, since they conclusively showed the powder to be innocuous when breathed by animals, it was, nevertheless, desirable to have additional reassurance with regard to its effect upon human beings. Through the courtesy of the Aluminum Company of America and especially the valued interest in this problem displayed by that Company's Director of Research, Dr. Francis C. Frary, a study was made of the records pertaining to the health of a group of 125 employees who had for many years been engaged in the manufacture of finely powdered, metallic aluminium for the paint and ink industries. The conditions were such that these employees had inhaled varying and oft-times very dense concentrations of this powder daily over periods ranging from 6 to 23 years, the average for the group being 12 years. X-ray pictures of their chests showed no abnormalities attributable to aluminium. Their general health seemed better than that of the 3,000 workers in other sections of the plant. In fact, the early films of three employees in this group of 125 showed shadows suggestive of minimal tuberculosis, which shadows were not discernible in films taken after considerable periods of exposure to aluminium powder. The harmlessness of aluminium was, by this study, reasonably well established at the outset, a finding subsequently verified by Ontario research on humans.

Jan 1, 1944

By B. S. -J. Kang, M. A. Alvin, J. M. Tannenbaum

"A load-based micro-indentation technique has been developed for damage assessment and non-destructive spallation detection of TBCs at room temperature. This micro-indentation technology has been further extended to the development of a high temperature (HT) test methodology. Elastic modulus calibration tests performed on Hl 3 Tool Steel to 500°C and Haynes 230 at 1000°C displayed excellent agreement with reported values. Moreover, indentation creep tests of Haynes 230 at 1200°C were found to be in agreement with known creep exponents as well. Finally, a HT thermal flux indentation apparatus was assembled for conducting TBC turbine component testing under high temperature moisture-containing environments (= 50% steam with controlled gas content temperatures up to 1250°C). Description and design considerations of this test apparatus are discussed. Preliminary tests of ReneN5/MCrAlY/APS TBC coupons in steam/air environments with in-situ HT micro-indentation testing are conducted. Furthermore, the coupon is removed and examined for damage assessment at periodical intervals.IntroductionLoad and depth relationships acquired throughout the indentation process provide insight to material mechanical properties such as elastic modulus and hardness. Unloading segment analysis of these load displacement curves are utilized in the acquisition of a material's elastic properties. Yet, indentation tests are complex processes involving contact mechanics, material nonlinearity and even fracture mechanics. Thus exact analytical solutions for these processes are difficult to obtain. As a result, much of the current knowledge regarding the indentation process has been acquired through experimental methods and finite element simulations. Initial efforts by Tabor resulted in the application of spherical indentation to obtain post-yielding stress/strain relationships [1]. Soon thereafter, analytical load-depth relations for elastic indentation were developed [2], yet it was Lure who further derived the explicit relationships for both spherical and conical indenters [3]. Improving upon this, these interactions were later extended to indenters with various geometries by various researchers [ 4]. Additionally, by establishing the linearity of the initial unloading slope within the load-depth curve, a relationship between elastic indentation depth, maximum load, unloading slope and indenter geometry was established [5]. From this a theoretical method by which elastic modulus could be determined was established."

Jan 1, 2011

By G. A. Vissac

In this paper we intend to deal particularly with the economic side of coal washing as it applies to our mines. We will then discuss why the dry-cleaning process has been selected, and give a brief description of our plant, dwelling only on its specific features and referring the reader to the numerous papers published on the subject for any details on the principles and machinery used in dry cleaning. ECONOMIC DISCUSSION The washery introduces an extra cost for depreciation, operation, and loss in treatment. A certain proportion of the coal, now being sold, and which the miners have been paid for. will have to be wasted. As a whole, the total increase in cost would be approximately 60 cents per ton. On the possibility of recovering this amount depends the success of the washery. There are two advantages to be expected from the washery, the first, which occurs at the mine and which will be certain; the second, more difficult to estimate, because it depends upon convincing our customers that they should pay more for a better product.

Jan 1, 1924

By R. L. Grayson, S. B. Bealko, L. L. Chasko, D. W. Alexander

In response to recent mining disasters and new mine rescue team legislation, NIOSH researchers conducted meetings across the United States with mine emergency response experts to investigate current needs and issues. Some of the issues include emergency response preparedness, mine rescue contests, real-life training capabilities and training facilities. Many new teams are being formed that must be trained for mine rescue team competitions as well as be ready to respond to a variety of mine emergencies, including a fire or explosion, a massive roof collapse, mine inundations or vertical shaft rescue situations. Therefore, it is important that these teams are adequately prepared and trained. This paper presents a summary of domestic and international coal mine rescue training facilities and identifies those that provide unique, real-life and/or state-of-the-art training. Research findings from this report will be used in further NIOSH investigations to improve coal mine rescue training.

Jan 1, 2010

By George A. Snyder

The presence of moderate to high concentrations of colloidal clays in coal preparation plant waters can cause serious operating and economic problems for a coal company. Among the host of possible problems are the following: 1) Poor separation of clays in the plant thickener, resulting in: a) Increased ash in the clean coal. b) Increased specific gravity of the wash water and decreased coal recoveries at the desired quality. c) Increased thickener operating costs in trying to overcome the problem. 2) Decreased solid concentrations in the thickener underflow and increased pumping requirements to meet solids withdrawal requirements.

Jan 1, 1979

By J. van Deventer

Ion exchange is widely used in hydrometallurgical operations for the recovery and purification of valuable metals. Special chelating resins have a high affinity for specific elements, allowing the selective removal of low levels of impurities from a background of highly concentrated valuable metal. Solvent-impregnated resins have been added to this group more recently, expanding the treatment options. These products find application in the purification of cobalt-rich liquor prior to the production of high-purity metal or metal salts. Impurities in copper-cobalt circuits that are typically targeted by ion exchange include iron, uranium, copper, zinc, nickel, bismuth, and antimony. Ion-exchange resins can also be used to treat tailings, thereby recovering additional valuable metal and improving the Environmental and Social Governance credentials of the operation. This article takes a look at various applications of ion exchange in copper-cobalt operations

Jan 1, 2023

By Qinghua Tian, Zhipeng Xu, Dong Li, Xueyi Guo, Liu Zhu

A possible process for extracting tellurium and antimony from a residue generated in alkaline sulfide leaching of telluriumbearing alkaline skimming slag was proposed. The central composite design was employed to define the optimal leaching conditions for tellurium and antimony extractions from the residue sample. Using a 23 factorial matrix, the best performance for tellurium and antimony extractions (96.36% and 99.64%) were obtained at 175 g L−1 Na2S concentration for 80 °C during 60 min. The notable degree for influencing tellurium and antimony extractions was leaching temperature, Na2S concentration, and leaching time. The analysis of variance results indicated that the regression model was significant and suitable to be used for the optimization of independent variables within the range. The model was validated under optimal operating conditions based on the experimental design results. Antimony and tellurium in the leach liquor were separated and recovered by H2O2 oxidation followed by Na2S-Na2SO3 reduction. 98.93% of antimony was precipitated selectively during H2O2 oxidation, while 95.06% of tellurium was precipitated during Na2S-Na2SO3 reduction. NaSb(OH)6 and elemental tellurium was obtained as the product.

By J. P. Welsh

Ground Modification construction is rapidly evolving in the United States. An assessment of the construction status of Ground Modification methods with their dates of introduction and general acceptance in the United States is summarized. Seven of these techniques are discussed in depth with short case histories; namely, Dynamic Deep Compaction, vibro-compaction, vibro-Replacement, chemical grouting, compaction grouting, slurry grouting and jet grouting. Additional case histories are presented to illustrate the trend of combining Ground Modification techniques to solve specific site problems.

Jan 1, 2010

By C. Lupi

"The energy consumption of copper production by electrowinning, generally represents more than 1/4 of the total energy requirement in hydrometallurgical traditional process (roasting, leaching, purification and electrowinning). The considerable saving can be achieved just in this step that requires about 2.2 kWhlkg of the produced copper. To save energy the cell voltage, or more appropriately its anodic component, can be reduced: that is because the anodic voltage represents the main component of cell voltage and so it is largely responsible for the excessive energy consumption in copper sulphate electrowinning.In this work some ways are studied to lower the anodic voltage. First the cobalt ions were added to the sulphate solution in order to study the catalytic effect on oxygen discharge. Then lead alloys anodes (Pb-Ag, Pb-Sb-Ag and Pb-Ca) were used to promote a better oxygen evolution as a result of a different anodic surface. Their behaviour was compared with the PbSb traditional ones. Finally, as already pointed out by several authors for zinc electrowinning, ethylene glycol was employed as anodic depolariser in order to verify its effectiveness in the case of copper electrowinning. By combining all the above-mentioned ways, energy saving ranging from 20% to 27% is achieved.All the tests were carried out on a laboratory pilot-plant for long time to simulate the industrial conditions. The obtained copper deposits were observed by SEM to highlight their morphology."

Jan 1, 1997

By Luana Ferreira de Carvalho, Aurelio Manço Garcia, Gustavo Sampaio Lopes, Jose Silvio Corsini, Davi Bastos Martins de Oliveira

The Enaex Mining Technical Solutions (EMTS) team, in partnership with the Anglo American Iron Ore Brazil drilling and blasting team, has developed a study aiming to optimize the blast design applied at the Minas-Rio project. The study consists of modeling the dynamic behavior of one lithological domain to determine the best configuration of drilling pattern, charge configuration, timing and sequencing of the blast designs applied at the mine in this particular rock. The first stage of the study was the recognition of the rock blast process in question, assessing key parameters that characterize this whole operation: geomechanical characteristics of the rock mass, implementation quality for drilling pattern and explosives charging (collar position, hole depth, explosive charge length and stemming size) and recognition of current blast designs. The central element of this study was the creation of a vibration attenuation and seed wave model which has allowed the characterization of this particular rock mass present in a region determined by the Minas-Rio team. The model is based on a near field vibration test, constituting a powerful tool in the design of blast parameters. The blast design developed from the damage model simulations basically modified the timing and sequencing. The aim of this study was to improve the fragmentation resulted by the blasting, considering the particle size requirements demanded by the primary crusher and to increase the productivity of the loading and hauling operations. The results were analyzed considering the effective productivity of the two different fleet types of shovels, where the authors have analyzed more than 46000 values of productivity from September 2017 to August 2018, taken from the Dispatch system. A significant increase in effective productivity of these load equipment was observed, 7% to the PC4000 fleet and 2% to the PC5500 fleet, values supported by statistical parameters and hypothesis tests.

By Chris P. Pistorius

Over the past few decades the carbon intensity of ironmaking and steelmaking has been reduced considerably through improved efficiency in blast furnace ironmaking, partial replacement of coke with less carbon-intensive fuels, and increased use of scrap and direct-reduced iron in steelmaking. To evaluate possible further reductions in carbon intensity accurate process information is needed. A preliminary test of the fidelity of publicly reported data as a source of process information is reported here. The sources are industry roundups of electric furnace furnace steelmaking and blast furnace ironmaking (published by the Association for Iron and Steelmaking Technology), and data recorded by the Environmental Protection Agency under the US Greenhouse Gas Reporting Program. From a comparison for an integrated steelmaking plant and an electric furnace furnace plant, it appears that the values from the two data sources are consistent. The comparison does rely on process details such as the quantitative relationship between injected oxygen and carbon emissions in electric furnace steelmaking.

By M Lynch, B White

The historic city of Charters Towers in North Queensland is underlain by an extensive labyrinth of old mine workings in a large number of flat lying, subparallel, main and cross-cutting cross reefs extending of the order of 5 km along strike and down to a depth of 700 m in parts. These old workings produced over 6.6 million ounces of gold at a grade of over one ounce to the tonne prior to closure in 1920.Citigold is progressing the development of a modern, high productivity, low cost new mine to extract extensions of these reefs as well as other as yet un-mined reefs. To do this it is changing the paradigm for operating in such circumstances. This paper first briefly reviews the setting for the development and then discusses the philosophies and concepts that Citigold is proposing to use, harnessing technology to create a mine that exemplifies more productive and safer mining based on operating in the digital age.The paper addresses how a modern approach is being applied to the planning of a mechanised, deep, narrow vein, hard rock gold mine under a city. It also describes briefly the successful æexperimentationÆ with longhole open stoping methods developed at the companyÆs small underground operation (the Imperial Mine) to the south of the city, which will also be expanded substantially as part of the Charters Towers Gold Project.The paper also addresses the development of new and/or modified technologies in the venture, with the objective of pursuing continuous and autonomous mining methods. The company is adopting a holistic systems approach, addressing people, process and technology in order to efficiently identify and locate the high-grade ore zones and then extract them effectively at a high grade by minimising waste development and haulage, dilution and energy consumption, and with minimal environmental impact.CITATION:Lynch, M and White, B, 2013. Brave new world autonomous mining systems, in Proceedings World Gold 2013 , pp 157-166 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Jiongtian Liu, Guixia Fan, Caom Yijun

A cyclonic-static micro bubble flotation column (FCSMC) is an effective separation device for fine grain treatment. The separation of fine ilmenite by FCSMC was explored in this work. The influence of reagents dosage (regulator, collector and auxiliary collector), pulp density, circulation pressure and aeration quantity on TiO2grade and recovery wasinvestigated.The optimal conditions of a rougher are follows: pulp density 45%, pH 5.0, MOH collector dosage 2800 g/t, diesel oil dosage 700 g/t, circulationpressure 0.19 MPa, aeration quantity 0.8 m3/(m2•min). The optimal conditions of a cleaner are follows: pH 4.0, circulation pressures 0.16 MPa, and aeration quantity 0.5 m3/(m2•min).A pilot plant continuous test with a rougher-cleaner by FCSMC for 72 hours was proceeded under the optimum conditions. Compared with industrial flotation machines, the concentrate grade of FCSMC is 48.11% with an improvement of 1.08 percentagepoints, while the recovery is 82.36% with 13.64 percentagepoints increment. Moreover, the flowsheet is simplified from six parts (a rougher-two scavenger-three cleaner) in flotation machines to two parts (a rougher-cleaner) in FCSMC. Proofs were also provided by the analysis of the by-size grade and recovery of concentrate.Results show the FCSMC is an effective separation device to recover -74 µm size fraction.

Jan 1, 2014

By Cawte D. C, Just G. D, Whitchurch K. D

The stringent marketing specifications included in coal contracts mean that coal producers must supply cleaner and more consistent coal than may have been formerly required. Geostatistics has the potential to aid in the accurate estimation of the washability characteristics of coal. A prediction method, the Kriged Service Variable Approach has been developed.A Computer Aided Drafting and Design system has proved useful in the development and application of the approach. The geostatistical approach has been tested against coal geological and borehole data and applications discussed.

Jan 1, 1987

By T Higuchi, K Fukada, K Takehara, Y Iwami, S Fujiwara

Following the Paris Agreement adopted in 2015 and the SDGs, reduction of CO2 emissions has been taken up as an issue worldwide, and the steel industry, which has a particularly large emission, is required to significantly reduce it. Most of the CO2 generated in the steel industry is generated from the ironmaking process, due to the use of coke and its raw material coal in the ironmaking process. JFE Steel Corporation has been considering the use of hydrocarbon-based gaseous fuels and liquid fuels as a partial alternative to coke breeze used in the sintering process since 2006, immediately after the Kyoto Protocol came into effect in 2005. In a laboratory study, a pot test was used to investigate the effect of the type of fuel, its amount and its injection method on the heat pattern in sinter bed. As a result, the authors developed a technology, in which a predetermined amount of gas fuel or liquid fuel was injected from the surface of sintering bed to extend the holding time of 1200°C or higher at which liquid phase sintering occurs in the layer, to improve the sinter strength while reducing the amount of coke breeze. The authors succeeded in putting this technology to practical use using hydrocarbon-based gas fuel in 2009 and achieved a maximum annual reduction of 60 000 tons of CO2 per sintering machine. In this report, the authors introduce the results of laboratory studies on the use of various energy sources, the practical application of the technology for injecting hydrocarbon-based gaseous fuel into the sintering machine, and the operational results.

Nov 8, 2021

By J. Grubb

"The undertakings described in the paper titled “Study on correlation of quantified coal rank with self-heating temperature” by Wang and Luo in the November 2015 issue of Mining Engineering (Wang and Luo, 2015) are mathematically sustainable and an acceptable extension of work performed by Smith and Lazzara (1987) for the U.S. Bureau of Mines. The paper is not an accurate explanation of the currently accepted leading practice for determining the propensity of a coal seam for spontaneous combustion. The paper could lead a practitioner to an oversimplified conclusion on how to determine the propensity of a coal seam to spontaneously combust.The spontaneous combustion of coal is a complex and not fully understood reaction. What is understood is that many more factors other than selfheating temperature (SHT) and coal rank are required to sufficiently evaluate the risk of spontaneous combustion in a particular coal seam. A superficial assessment can lead to an improper response to the risk. Some statements on the next steps through an appropriate literature search would have made the authors’ conclusions more credible.The SponCom 2.0 software, updated by the National Institute for Occupational Health and Safety (NIOSH) in 2011, provides a path for evaluating the susceptibility of a coal seam to spontaneous combustion. In addition to proximate and ultimate analyses to establish coal rank, and therefore an estimate of SHT, the program includes the history of heatings, friability, seam thickness, overburden thickness, rider seam presence, pyrite presence, face and butt cleat densities, geothermal source presence and other geological features in the assessment. Mining conditions including floor heave, rib sloughage and rate of advance are also assessed to conclude a propensity for spontaneous combustion."

Jun 1, 2016

By F Shi, W Huang, D Seaman, K Runge

High Voltage Pulse (HVP) technology is a novel process that could potentially be the step-change needed in ore processability in the mining industry. The propensity of high voltage pulses towards mineral-enriched ore particles during treatment makes this technology selective and has the potential to enable ore pre-concentration by size separation. In this study, the potential for pre-concentration of a low grade copper-gold ore sample subjected to HVP pretreatment is investigated and compared to that achievable after mechanical breakage in JKMRC’s rotary breakage tester (JKRBT). The data show that a better pre-concentration result can be achieved after HVP processing than conventional breakage. The gold pre-concentration potential is much better than that observed for copper. 4D HVP pre-concentration characteristic curves were produced to assess the metallurgical performance possible as a function of energy input. The case study shows that when targeting a nominal metal recovery of 90 per cent for gold, the HVP pre-concentration technique can split the low grade ore (0.9 ppm gold and 0.28 per cent copper in the feed size 26.5-37.5 mm) into two components – a low grade oversize material (0.3 ppm gold and 0.15 per cent copper) and a high grade undersize material (1.0 ppm gold and 0.3 per cent copper). The mass split to the low grade is 23 per cent. Under this mass split scenario, gold recovery to screen undersize is 90 per cent and copper recovery is 85 per cent. The HVP treatment of this feed size requires a specific energy (spark) of 2.8 kWh/t.There is further research that would be required before industrial uptake of the HVP pre-concentration technology would be possible. This paper also outlines the research challenges that need to be overcome.CITATION:Huang, W, Shi, F, Antonio, C, Runge, K and Seaman, D, 2018. High-voltage pulse pre-concentration study using a low-grade copper-gold ore, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 327–338 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Glenn Stevens

After 40 years of operation with the original design, Pan Pacific Copper determined it was necessary to rebuild the Saganoseki Flash Smelting Furnace to continue safe operation. The original design employed a rigid steel frame, which, through hearth growth, led to severe distortion of the frame. Contributing to the continued growth of the hearth were thermal cycles that occurred during the government mandated annual shutdowns. Hatch designed a unique sprung bound, pivoting binding frame to maximize crucible size within the existing furnace footprint, while integrating the PPC designed cooling jackets. The bound system maintains tight brick joints, while the new conductive hearth design with integrated bottom cooling produces a protective freeze layer to accommodate higher furnace throughput. Minimization of furnace downtime for the rebuild was achieved through effective construction planning, highly trained contractors, and through an efficient start-up and ramp-up to full production.