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By F. Urekar, R. B. Pankhurst

"Air spaces and air gaps in an explosives column are known to allow greater distribution and cushioning of explosive energy from the rock mass. This energy distribution is enhanced if the explosives ' gases can be confined in the borehole for as long as possible by plugging and stemming above the air space.Power Plug is an inflatable plug which can seal a borehole at any point to separate the stemming from an air gap and explosive toe load.IntroductionThis paper will discussion-going work by C-I -L Inc. and operators of two open pit mines to study the results of using Power Plugs:I. Pit wall stability - the authors have found the Power Plug effective for wall control blasting in open pit mines.2. Selective mining of coal seams - the authors work shows the Power Plug allows mining selective coal seams by predrilling underseam waste wedges.Pit Wall StabilityWall stability in an open pit mine is essential for safety. Good wall stability can be achieved with wall control blasting techniques which cushion the effect s of the explosives charge by decoupling the charges from the borehole wall. The usual method of decoupling a charge in a large-diameter rotary borehole is to load the explosives in tubes (Fig .I) . We now believe the air deck system is effective in sea ling a borehole above the explosive charge to create an air deck within the borehole which will cushion the blast.In a linear decoupled charge, an air annulus surrounds the explosives charge and cushions the effects of detonation genera ted gases on the pit wall. In an air deck, i.e. with the hole plugged at the collar, the gases genera ted by an explosive toe load are sealed in the empty borehole column. After a period of time, these trapped gases produce radial cracking between holes along the entire length of the borehole.It is common practice to employ de coupled explosive charge columns in the borehole to limit blast damage to surrounding rock. The exact mechanism of energy transfer in such blasts, however, is not well understood. Interruption of the continuous explosive column in a borehole by means of stemming, or air decks, may also be viewed as another form of decoupled blast. Decoupling of the explosive charge from the borehole wall affects both explosive energy release and explosion pressure developed in the borehole."

Jan 1, 1988

By Stanley G. Hutton, Robert Brubaker

"It has long been recognized that mining workers subjected to high levels of hand-transmitted vibration may suffer from vibration-related complaints. Prolonged exposure to whole-body vibration may also result in adverse effects. In this study, the effects of vibration on mining workers are examined. Previous work documenting the occurrence of vibration-related disease is reviewed. From this work, it is apparent that operators of hand-held pneumatic rock drills are exposed to a significant risk of developing vibration disease. Vibration levels recorded on the rock drills now in use are presented and shown to exceed levels recommended by a proposed ISO standard.IntroductionThe possible harmful effects of exposure to excessive vibration levels have long been recognized, particularly among operators of hand-held tools. Numerous cases have been reported of a vasospastic disorder commonly known as vibration white finger disease (VWFD), which was a term coined by the Industrial Injuries Advisory Council in Scotland in 1970(1 ), Those suffering with the disorder have frequent vasospastic attacks in which the fingers, hand and, in advanced cases, the lower arm turn white and numb, usually after a cold stimulus. Advanced stages of VWFD have been reported in which the skin becomes ulcerated and gangrenousm. The incidence of the disease has been particularly serious in the forest industry due to the extensive use of chain saws. However, in recent years, the introduction of antivibration saws has resulted in a significant reduction in the occurrence of the disease.In a recent report for the Canadian Department of Supply and Services - Energy, Mines and Resources, Hutton & Brubaker considered the effects of vibration on workers in the mining industry. In this report, the physiological and medical effects of vibration were considered, relevant vibration standards were discussed, previous vibration measurements were documented and field measurements carried out. In the present paper, the results recorded in this study will be summarized, together with results that have been previously published relating to vibration levels existing in the mining industry."

Jan 1, 1982

By B. R. Bowerman, W. J. Thoburn, M. J. Humphris

"Nickel granules are produced for carbonylation by pouring a molten stream into a path of high pressure water. Granules and water are separated in dewatering bins. The overflow, which contains up to 0.1 weight percent solids, was initially cooled and recycled to the granulating step. However, the rate of buildup of these solids in the handling system was intolerable. A lamella thickener was installed to solve the problem by removing solids from the dewatering bin overflow. Its description, application and performance to date are discussed.The lamella thickener treats a slurry containing about 0.1% solids of which about 30 weight percent is less than 325 mesh. It recovers 80 to 90 percent of the input solids in an underflow slurry containing 90 weight percent solids. Since its installation the frequency of cleanout of the recycle water handling system has dropped from about once per month to about once or twice per-year."

Jan 1, 1977

By Mike Broczkowski, Laura Dewhirst, Kieran Large, Angelo R. Fernando, Heather Daigneault, Jim Johnson, Randy Wiens

The radioactive isotope radium 226 is a contaminant of potential concern in effluent waters from metal mining operations in Canada. Acceptable release levels of radium 226 are governed by Metal and Diamond Mining Effluent Regulations. Since radium is invariably present as a companion element in uranium ore, monitoring and controlling of radium 226 is a must for uranium mining operations. Measurement of radium 226 is traditionally carried out through a radiochemical technique involving selective co-precipitation of radium with barium sulphate followed by alpha spectroscopy for quantification. As of 2010, Cameco has also been using an ICP-MS based radium analysis method developed in collaboration with a research team at Trent University, Peterborough, Ontario. This method, which is highly automated and requires significantly less sample handling, with improved turn-around-times, is being used by Cameco site laboratories at the McArthur River and Cigar Lake mines as well as the Port Hope Conversion Facility. This paper compares the benefits and drawbacks of this new method, compared to the traditional alpha counting procedure drawing from almost ten years of field experience.

Jan 1, 2020

By C. G. Williams

This paper describes the planning, development and operation of the Highvale Mine to supply coal to both the existing Sundance and the approved Keephills thermal power plants of Calgary Power Ltd. Reference is also made to the company 's Whitewood Mine, which feeds the Wabamun thermal plant .

Jan 1, 1979

By R. Khanna, K. Hyun Ko, A. J. Berkovich, J. Hook

"The co-pyrolysis of synthetic polymer polyethylene terephthalate (PET) and agricultural wastes (naturally occurring polymer-macadamia nut shell) was investigated in the temperature range 473K to 1273K using a horizontal furnace with an aim to understand their thermal degradation under isothermal conditions. In-depth characterization of pyrolysis residues was carried out using x-ray diffraction (XRD) and solid state nuclear magnetic resonance (NMR) for carbon structure, and through determination of the concentration of unpaired electrons using electron paramagnetic resonance (EPR). In previous studies, it has been found that PET thermally decomposes ~ 650K-700K, releasing (~80 wt % of initial weight) gaseous products due to random chain scission. In the case of macadamia nut shell, three types of byproduct can be obtained from pyrolysis: char, tar and gaseous products. In the co-pyrolysis of macadamia nut shell with PET in 50-50 wt% ratio, total product weight ratio could be modified with the addition of PET acting as a hydrogen source. This is because a recombination of thermal cracking products of cellulose could be suppressed by hydrogen from PET, which will later lead to an enhancement of tar formation. In addition, pyrolysis around 673K is sufficient for bond cleavage to occur in cellulose and lignin leading to the formation of negatively charged activated carbon with high surface area, providing bonding sites for volatiles evolving from PET. Therefore the co-pyrolysis may be able to enhance the product yield (tar/char/solid carbon residue) along with a reduction in the release of gaseous products. During the co-pyrolysis, temperature was found to have a significant influence on the kinetics of thermal degradation and solid residual by-products after co-pyrolysis.INTRODUCTIONPlastics are being used worldwide in a wide range of applications in the modern society; their usage has resulted in increasingly a massive waste problem. The production of most synthetic plastics requires hydrocarbons that are produced from petrochemicals derived from fossil oil and natural gas, a non-renewable source (Speight 2011). Currently, plastic manufacture utilizes ~4% of world oil and gas production, and it is expected to drive further increases in petroleum demand by 1-2% due to their large volume of manufacture (Hopewell, Dvorak et al. 2009). Landfilling and incineration of plastic waste are the two main routes to plastic waste management (Encinar and González 2008). In Australia, only 10% of waste plastics were recycled in 2006 (White and Hyde 2011). This means that large amount of fossil fuels from plastics has either been simply burned for energy recovery or buried in the ground. There is an urgent need for developing alternative avenues for recycling waste plastics. Our group at UNSW has carried out extensive research on the recycling of waste polymers as carbon resource in steelmaking including slag foaming and carbon dissolution from waste plastics into liquid steel at 1600°C; the effect of basic plastic characteristics such as chemical composition, structure, bonding network etc. was examined (Sahajwalla, Rahman et al. 2009)"

Jan 1, 2012

By Kazuteru Tozawa, Robert G. Robins

"The stability of calcium arsenate is discussed in relation to the possible misuse of lime in the treatment of gold processing waste waters. Stability diagrams have been derived and experimental results cited to show that calcium arsenate has a higher solubility in neutral to alkaline solution than has previously been recognized and this solubility is further enhanced by the presence of carbon dioxide, bicarbonate or carbonate.IntroductionThe removal of arsenic from gold mine waste waters has been of interest for more than thirty years, but with the recent emphasis on clean water standards there has been renewed activity in relation to that problem. The processing of gold-bearing sulphides which contain arsenopyrite and other complex arsenic sulphides is well established. Initial roasting to oxidize the sulphides leaves the arsenic in the form of both arsenic and arsenic, in which forms it is soluble in the subsequent leaching stage. Further oxidation of the leach liquors is required before the well-established procedure of precipitating calcium arsenate with lime, which is carried out despite an immense lack of knowledge of the calcium-arsenic-water system.The solubility product and free energy of formation for Ca3(AsO4)2, which are to be found in recent and reliable sources of data, originate from the work of Chukhlansev, whose experimental determination of the concentration of calcium from the solubility of calcium arsenate in solutions of various pH yields the results plotted in Figure 1. This is the work which has resulted in a wide acceptance of the ""insolubility"" of calcium arsenate and the use of lime to stabilize arsenic in that form.Laguitton attempted to further elucidate the chemistry of the lime addition method for treating arsenical waste waters from gold processing operations. The low solubility product for Ca3(AsO4)2 was the basis for his examination of likely chemical equilibria in the system. Laguitton and other workers have not considered atmospheric carbon dioxide as an important component in this system."

Jan 1, 1982

By D. G. Tisdale, W. Curlook, J. M. Toguri

"In this study, the vapour phase reduction of titanium tetrachloride conforms to the traditional Kroll chemistry, but employs argon as an inert carrier gas and requires a higher reaction temperature of 1150°C to 1250°C. A vapour phase reaction is advantageous because titanium is the only condensed phase present, and the metal can be collected free of magnesium or magnesium chloride, in marked contrast to the titanium sponge produced by the conventional Kroll process. The yield of metallic titanium from the reaction was determined as magnesium additions ranged from 36% to 168% of the stoichiometric requirement. Yields of over 99% were obtained when an excess of magnesium was present. Although the collection efficiency was low, metallic titanium was collected at the reaction site, where all other species were present as vapours. Magnesium and chlorine concentrations in the collected titanium were less than 0.3%.IntroductionA proposed method (Curlook, 1987) for titanium production has been investigated as an alternative to the conventional Kroll process (Kroll, 1940). The advantages of the new process include a simplified means of recovering the product metal, and a potential for lower overall energy consumption and greater product purity. A higher reaction temperature for the reduction of titanium tetrachloride results in a vapour phase reaction, rather than the conventional liquid phase reaction. This is the major conceptual difference between the proposed and the established (Kroll) processes.This study focussed on optimization of the process chemistry and briefly examined the issue of product deposition and collection. The reduction of titanium tetrachloride with magnesium, to produce metallic titanium and gaseous magnesium chloride:"

Jan 1, 1997

By B. Qiu

The large surface ground movements induced by underground mining could threaten the safety of the pipelines laid across the subsidence-prone area. Existing analytical methods for the stress analysis of buried pipeline over mine subsidence area were based on the assumption of ?thin? pipeline, which limited their applicability. This paper presents the improved model with the capability to determine the stress distribution of the ?thick? pipeline. The pipe-soil interaction in this model was also updated to adapt various pipe soil contact conditions. In addition, the time-dependent effects of dynamic subsidence effects were also added to the model. A case of protecting a long section of a buried large-diameter pipeline over two longwall panels in a shallow mine is shown. The stress distribution along the pipeline is determined and the overstressed sections are identified. A partial uncovering plan was developed based on the predicted stress and complicated terrain at the site.

Aug 1, 2013

By W. J. Wolfe

"Quartz Hill is a large, low- to moderate-grade quartz vein stockwork porphyry molybdenum deposit, discovered in 1974 during a regional stream sediment geochemical reconnaissance survey of southeast Alaska conducted by United States Borax and Chemical Corporation. Mineralization is localized in the upper parts of an Upper Oligocene (30 Ma) composite quartz monzonite stock which is emplaced discordantly into older Cretaceous to Early Tertiary terrain of the Coast Range igneous metamorphic complex of the northwest North American Cordillera. Subsequent fault-controlled, complex multi-stage intrusion, concentrated in the core of the Quartz Hill stock, produced successive pulses of hydrothermal alteration and molybdenum mineralization at about 27 Ma. Overall, the deposit is tabular and flat-lying and well suited to open pit mining. The 0.05% MoS2 grade limit covers an area of approximately 1500 m by 2750 m and extends to a maximum depth of 520 m below surface. Details of grade distribution show two separate lobes of higher grade material within the larger low-grade deposit.A ten year program of exploration drilling, underground development, sampling and metallurgical testwork led to a 1983 feasibility study based on a resource of 1600 million tonnes grading 0.127% MoS2 at a 0.08% MoS2 cutoff The large size of the deposit and its homogeneous grade distribution, typically showing gradual outward decrease of grade, makes in pit grade selection practical at several cutoff levels. Cominco Ltd. now reports a Probable Resource of 210 million tonnes averaging 0.22% MoS2 with a further Possible Resource of 1100 million tonnes averaging 0.12% MoS:z. At low molybdenum metal prices which have persisted for 10 years since the molybdenum price spike of the late 1970s and early 1980s, the Quartz Hill deposit is sub-economic."

Jan 1, 1995

By Avi Nanda, Robert Brandt, Alex Piatkiewicz, David M. Jones

In 2010 the United States Environmental Protection Agency (UESPA) revised the National Ambient Air Quality Standards (NAAQS) by lowering the permissible value to a 1-hour average SO2 concentration of 75 ppb. In 2012, the USEPA designated the Miami area as non-attaining for the new SO2 NAAQS. A number of options were studied to assist in bringing the Miami smelter into attainment with the new standard. The chosen solution included: Installation of a large tertiary hooding system over the converter aisle; Hooding of the anode vessels and treatment of the anode gas in a baghouse; Installation of a large 2,325,212 Nm3/hr caustic scrubber to treat the captured converter fugitives and anode off-gases; Installation of a secondary ESP for the tapping fugitive off-gas treatment system; and the continuous scrubbing of all acid plant tail stack gases. The modifications have reduced smelter SO2 emissions by 85%, achieving a world class SO2 stack emissions rate of 0.45 kg of SO2/tonne Cu. INTRODUCTION The Freeport McMoRan Miami smelter has been previously described in literature (Steinborn, Pasca, Sallee, Binegar, Bhappu). For the sake of brevity a brief description is given here. The Miami smelter is located 129 km east of Phoenix, Arizona near the town of Miami, Arizona. The smelter was established in 1915 and has undergone a number of process upgrades and modernizations over the years. The present smelter consists of an Isasmelt furnace, an electric settling furnace, four Hoboken converters, two anode refining vessels & one casting wheel; and one double contact sulfuric acid plant. Concentrates are railed & trucked to Miami from four Freeport McMoRan mines located in Arizona & New Mexico. The wet concentrates, typically containing 10% H2O with a Cu/S ratio of 0.85, are smelted in an Isasmelt furnace to a matte grade of 58%. The entire output from the Isasmelt is laundered into an Elkem electric furnace (originally installed in 1972 as the primary smelting furnace) for separation into matte and slag. Slag containing 0.85% Cu is skimmed from the electric furnace and discarded. Molten matte, containing 60% Cu, is tapped from the electric furnace and processed in one of four Hoboken converters to produce blister copper. Two anode refining vessels further refine the blister copper before the final product is cast on a single, 30 mold, casting wheel. All of the anodes produced at Miami are shipped to the Freeport McMoRan electrolytic refinery in El Paso Texas for refining into cathode copper. Smelter off-gases from the Isasmelt, electric furnace and Hoboken converters are combined and treated in a double contact acid plant to produce sulfuric acid. Acid produced at Miami is internally consumed at Freeport McMoRan mines in the region.

Jan 1, 2019

By W. M. Armstrong, John A. H Lund

The paper describes an investigation of some of the tensile properties of single crystal vanadium, poly-crystalline vanadium and polycrystal-line tantalum, in the range of: W°C to -196°C. Techniques employed in the preparation and testing of specimens are discussed in detail. Some results of determinations of the temperature dependence of yield stress and ductility are given, and discussed in terms of the Cottrell-Bilby Theory of yielding. At subnormal temperatures, all the body-centred cubic transition metals in the Periodic Table exhibit; a) the "yield phenomenon" in tension, b) a strong temperature and strain rate dependence of yield stress, and c) a large decrease or complete loss of ductility. The yield phenomenon (existence of an upper and lower yield point) has been explained by Cottrell and Bilby ( 1) in terms of the dislocation-locking effect

Jan 1, 1961

By Kazutoshi Haga, Batnasan Altansukh, Yasushi Takasaki, Mohd Yazid Bin Abdul Razak, Atsushi Shibayama

"In this study, the volatilization behaviour of arsenic (As) and antimony (Sb) from arsenicantimony bearing minerals such as tennantite (Cu12As4S13)/tetrahedrite (Cu12Sb4S13) in copper ore was investigated using a roasting process. Specifically, the thermal decomposition of tennantite and the arsenic volatilization were investigated under nitrogen and air atmosphere. The roasting experiments were performed at temperatures ranging from 500 to 1,200oC and different retention times using a laboratory electric furnace. The results indicated that over 95% volatilization was achieved at 700oC. On the other hand, when the temperature increased to 1,200oC, volatilization rate of Sb reached to 90%. Therefore, volatilization of Sb requires high temperature compared to As. It suggests that As and Sb can be separated using temperature difference. Selective removal of As is possible at 700oC, subsequently Sb can be recovered as a volatilized product by increasing the temperature to 1,200oC. Meanwhile, volatilization of Cu and Fe was not observed on these conditions. The content of As and Sb in the residues obtained from roasting at 700 and 1,200oC was less than 0.3 and 0.75 mass%, respectively. The Cu content in solid residue at 1,200oC increased to 34 mass%. The clean copper concentrate with lower amounts of arsenic and antimony was obtained from the process. INTRODUCTIONRecently, arsenic (As) and antimony (Sb) contents in copper (Cu) concentrates are increasing year by year. Arsenic and antimony are present with Cu minerals such as enargite (Cu3AsS4), tennantite (Cu12As4S13) and tetrahedrite (Cu12Sb4S13) that associate with copper sulfides [chalcopyrite (CuFeS2) and bornite (Cu5FeS4)]. They are normally concentrated by flotation and treated in copper smelters. However, treatment of copper concentrates containing high amounts of arsenic and antimony by a smelting process is difficult due to environmental implications of toxic arsenic and antimony. As demand for copper continues to grow, the need to source copper from several types of resources including those that contain high levels of As/Sb becomes necessary. Therefore, a novel processes for the treatment of As/Sb bearing Cu concentrates are required. Reviews on copper resources such as enargite, tennantite and tetrahedrite containing high amounts of arsenic and antimony are covered widely in literatures by many researchers (Padilla et al., 1998; Welham, 2001; Vinals et al., 2003; Guo & Yen, 2005; Balaž & Achimovicova, 2006a; Filippou et al., 2007; Mihajlovic et al., 2007; Lattanzi et al., 2008)."

Jan 1, 2016

By B. E. Halbert, K. T. Himbeault, S. L. Fernandes, R. L. J. Phillips, B. J. Topp

The Beaverlodge uranium mining and milling facilities operated from 1952 to 1981 with about 94% of the ore extracted from the main underground mine and 6% from smaller satellite deposits. Decommissioning work occurred from 1982 to 1985 involving periods of shutdown, salvage and reclamation. Transition phase monitoring, leading to eventual delicencing commenced in July 1985. Over the last 15 years, discharge from the tailings management facility (TMF) and a fresh water stream, impacted during the operational phase by tailings spills, has improved in water quality for most parameters of concern. Loadings to the environment of three key contaminants (radium-226, total dissolved solids, and uranium) have consistently been less than during the operational phase with radium-226 having the greatest variability. Outstanding environmental issues associated with the recovering drainage system formerly used for tailings disposal, are being addressed in an enhanced environmental monitoring program to commence in 2000. Changes in water chemistry and the natural re-introduction of aquatic organisms are issues of concern. In the meantime, application for release from selected satellite areas commenced in 1999. This paper reviews the issues which have arisen during the transition phase, outlines how they have and are being addressed, and provides a comparison of original and current predictions of the recovery process under way at the former Beaverlodge mine site.

Jan 1, 2000

By C. C. Walden, A. Bruynesteyn

"Chemical and biological aspects of the formation of acidic effluents from sulfide waste materials are discussed. Test procedures to determine the acid producing potential of waste materials, as well as the characteristics of such acidic effluents, are presented. Practical applications of the test procedures are discussed with reference to predictior of environmentally unacceptable drainage and to estimation of metal recovery by dump leaching.INTRODUCTIONNatural leaching of sulfide minerals, exposed to the atmosphere, has been occurring for geological time. For centuries, man has been aware of the acid drainage originating from coal workings, copper mines and waste dumps. With the advent of the technical sciences, the processes involved in acid mine drainage production were considered to be solely chemical in nature. However, in 1947, it was shown (1) that a specific microorganism, called Thiobacillus ferrooxidans, was responsible for acid mine drainage from coal workings. It was demonstrated that under suitable conditions - this bacterium oxidized pyrite and marcosite in the coal to ferric sulfate and sulfuric acid. Numerous studies have subsequently demonstrated that - under suitable conditions - Thiobacillus ferrooxidans can attack most sulfide minerals, producing weak sulfuric acid, oxidizing ferrous to ferric iron and solubilizing other metals present (notably copper and zinc) as their sulfate salts."

Jan 1, 1980

By M. Courchesne, C. Barbery, D. Hodouin, C. Carrier

"The carbon-in-pulp process for recovery of gold dissolved in dilute cyanide solutions, in the presence of solids, has now replaced the convedntional processes of pregnant liquid/barren solids separation followed by Merrill-Crowe precipitation. Most plants built over the past ten years incorporate a CIP section. The process is described as cheaper in capital and operating costs, and few major start-up or operational difficulties are reported. For the purpose of the present paper, the CIP process will be assumed to consist of the following sequence of operations (Figure 1):- the slurry stream coming out of the cyanidation circuit is first screened to remove any tramp oversize material. Gold dissolution is assumed to be complete before entering the CIP circuit.- the slurry is sent into a series of agitated tanks in which it is mixed with activated carbon. The carbon particles size is much coarser than the top size of the ground ore. The tanks are fitted with screens that allows the slurry to overflow continuously into the next tank, while retaining the carbon in the tank. Slurry dilution is adjusted to prevent carbon from settling in the tanks. Agitation intensity is kept low in order to minimize carbon abrasion.- carbon is transfered from tank to tank in a discontinuous manner. According to a specific schedule, the carbon from tank one is removed, then carbon from tank two is sent to tank one, and so on, till the last tank, which is filled with regenerated carbon corning from the elutionregeneration section. The amount of carbon removed, the transfer from tank to tank, the sequence of transfer, the carbon inventory in the various tanks are parameters which are, up to a point, at th2 discretion of the operators, as long as they remove, batch wise, an amount of loaded carbon containing a similar quantity of gold to the one that has entered the circuit since the last transfer."

Jan 1, 1987

By T. S. Smith

INTRODUCTION IN PREPARING this paper for the District 4 Meeting, three factors had to be considered. First, the paper must fit the time alloted; second, it must give a general picture of the geology for those unfamiliar with the property; and third, it must contain some new material in order to be of interest to local delegates. The most comprehensive extant discussion of the geology of the property of McKenzie Red Lake Gold Mines, Limited, is contained in Horwood's report on the general Red Lake area ( 1). This report is the 'bible' of the area, and a general paper on the geology of this particular mine would almost certainly appear to be a condensation of it. It was thought, therefore, that the most suitable procedure would be to base the general outline on Horwood' s report, to extend that outline where possible from information gained since its publication, and finally to leave dangling for the contemplative geologist some of the ideas and problems which ?are currently under consideration. LOCATION AND HISTORY The property of McKenzie Red Lake Gold Mines, Limited, is in Dome township, in the Red Lake mining division of northwestern Ontario. The mine is on McKenzie Island, about four miles north, by water, of the Hasaga mine and old Howey mine.

Jan 1, 1951

By H. Yoshida, H. Hatta, T. Suzuki

"The effect of the copper and magnesium contents and quenching rate during quenching on the age hardening behavior of 2000 series aluminum alloys was investigated. For the higher copper-containing specimens as conventional alloys, like AA2024, precipitation of the stable phases increased as the quenching rate decreased under the as-quenched conditions. The maximum hardness after the artificial aging of air cooled(AC) specimens was much lower than that of the water quenched(WQ)specimens. On the other hand, for the lower copper-containing specimens, coarse precipitation did not increase even in the case of the AC. The age hardening behaviors of the WQ and AC were very similar such that the maximum hardness and aging rate were almost the same. Many parts of the fine precipitates that increased the hardness were thought to be the GPB zone or fine S’ phase for the WQ and relatively coarse S’ phase for the AC. From the calculated CCT(continuous cooling transformation)diagrams, the lower copper-containing specimens could maintain the copper and magnesium in the solid solution state during the AC, so they could be quenched at a rather slower quenching rate like the AC.INTRODUCTIONThe 2000 series aluminum alloys, containing copper and magnesium as the major chemical components, are some of the well-known heat treatable aluminum alloys. These alloys have a high quenching sensitivity, thus the age hardening ability of these alloys decreases with as low quenching rate. To prevent the decrease of the age hardening ability, quenching is done by a method such as water quenching, which is not very efficient in an industrial situation, because the method requires such large equipment. For these alloys, reducing the quenching sensitivity helps them to be produced in a rather convenient way. For example, 6000 series alloys such as A6063 have low quenching sensitivity, thus they could be quenched by only air cooling just after extrusion and they do not need water quenching. Based on these reasons, investigations of these alloys with high copper and magnesium contents have been conducted in the past to find a way to lower the quenching sensitivity by adding transition elements such as manganese, chromium and zirconium (Kanno, Suzuki, & Itoh, 1986; Suzuki & Itoh, 1986; Kanno, Sakuma, Muromachi, & Watanabe, 1988). However, very few studies have focused on the quenching sensitivity of the lower copper and magnesium containing alloys because of their usage for structural components with high strength, and most of the past studies have used only the fast quenching method like water quenching. On the other hand, from our recent results, there is a possibility to lower the quenching sensitivity of 2000 series alloys with lower alloying elements. In this paper, the effect of the copper and magnesium contents with lower alloying elements and quenching rate, especially in case of slower quenching rate than conventional quenching method, on the age hardening behavior of the 2000 series alloys is investigated by the hardness measurement, structure observation and thermal analysis."

Jan 1, 2018

By R. J. Balfour, T. L. Papucciyan

"INTRODUCTIONCapital Cost considerations are basic to feasibility in the achievement of success for Mineral Processing Projects as much as or more than in many other industries. Capital cost is an important factor ae it 1R the unit of measurement for process engineering economic decisions. As a result of ever increasing complexity, alternatives of process and remoteness of site, there is an ever increasing emphasis on accurate estimating and the attendant cost control systems in the international market of today for the Mineral Industry where initial plant costs are becoming a more important factor than operating costs. An undervaluation means trouble ahead. An over-cautious assessment may bring an unnecessary abandonment of a project. Consequently, the ultimate cost must be predicted early and accurately and must be controlled to this parameter during the design and construction phases. Cost Est!~ mating is one of a variety of project management tools used to assist in planning and achieving the optimum balance between Quality, Cost and Time, the eternal triangle of evaluation, namely obtaining a project of acceptable quality at minimum cost and on time. In order to attain these established objectives, proper planning, organizing, coordinating, monitoring, adjusting and controlling the design, procurement and construction elements of the project are essential.This project management approach based upon the principle of a Task Force under single management, comprising a complete service organization, requires a substantial number of qualified individuals specialized in their own field and capable of working together as a team to perform their various functions effectively. The Task Force is supported by their chiefs of discipline and performs in accordance with established procedures and standards under the leadership of a Project Manager.General Engineering Company Limited with the backing of the full resources of Surveyer, Nenniger & Chenevert and its total staff of approximately 1,0009 offers the complete project management service to the Mineral Processing Industry of North America and the rest of the world. As mine sites become more remote and difficult of access, the need for an experienced team of specialists who work under the Task Force principle, with well established standards and procedures becomes even more important. Our long history of successful pro1ecta in this field has been our training ground for the fulfillment of this need."

Jan 1, 1972

By PAUL L. DEAN

Industrial mineral deposits are widespread in Newfoundland and Labrador and a variety of commodities are produced. The province has the only pyrophyllite mine in Canada and also produces asbestos, gypsum, silica, barite, limestone, gemstones, cement and other structural materials. Large reserves of these and other industrial minerals are known and several deposits are likely future producers. Most producers are wellestablished and have large tonnages of ore reserves.

Jan 1, 1984