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By Andrew Cormier

"The Early YearsThe Grand Lake coal fields in New Brunswick undoubtedly can claim the distinction of being the first part of North America from which coal was mined and exported. The diaries of the Governor of Massachusetts during the first half of the 17th century clearly establish this fact. There is also a reference in the Massachusetts Colonial Records which indicate that coal exports to New England were carried on as early as 1639.It has generally been believed that Cape Breton mined and exported the first coal; but no account has yet been found to show that this took place earlier than 1676. Both at Grand Lake and Cape Breton the coal was near the surface and removed by hand.When the country passed entirely into British control, Joseph Garrison, a grantee of Maugerville in 1765 moved to Jemseg. While surveying the north side of Grand Lake he discovered outcroppings of coal on the shore of the lake and further inland along the banks of streams. It was he who named Newcastle Creek in reference to Newcastle in England, which was widely known for its coal mines. Joseph Garrison died in 1783, the same year that an influx of United Empire Loyalists increased settlement in Newcastle Creek in the area now known as Minto. Many Loyalists also settled on the shores on both sides of Grand Lake.At a number of points where streams cut channels through the overlying strata, the coal seams were exposed and it was at such outcroppings that the early operations were carried on. A tunnel was driven in the seam from the foot of the bank, affording both an outlet for the coal and natural drainage from the workings. The coal was loaded into boxes and wheeled over wooden tracks to a point on the surface where it could be dumped into wagons and hauled either direct to destination or to where it could be loaded into boats and conveyed via Grand Lake, Jemseg and Saint John river to points of distribution.In the latter part of the 18th century and first years of the 19th century, farmers were undisturbed by mining the coal found on their lands. This was soon to change and resulted in many years of contention between landowners and the Legislative Assembly.New Brunswick became a separate province from Nova Scotia in 1784 and the seat of government moved from Saint John to Fredericton in 1788. The new province had its first priorities; the establishment of counties, the building of roads, and the development of its natural resources. From 1805, records of coal and land development are fairly complete. These records show the increasing interest of the Province in developing the coal fields. This interest resulted in the granting of coal leases to many friends of the government, without any regard for the wishes of the farmers who owned and had occupied the land for many years. The farmers fought back with lawsuits and other forms of dissension but with little success. By the end of the 19th century there were very few farm operators left in the area."

Jan 1, 1992

By D. L. Johnston

"Function and ApplicationsWater-only cyclones, (WOC) are a dynamic mineral separator which cause minerals to separate in a water medium by virtue of difference in specific gravity. Figure 1 shows diagramatic plan and sectional views of a water-only cyclone.A slurry of mineral matter and water is fed through the inlet opening under gravitational or pump pressure. The combined effect of centrifugal action and conical shape is to concentrate the heaviest fraction of mineral on the periphery and bottom of the cyclone. This layer of higher specific gravity particles increases in thickness and density between the cyclone inlet and apex. The action in the bed of higher gravity particles formed in the flattened portion of the cone surrounding the tip of the vortex finder deter;nines the specific gravity of separation or cut-point. Mineral particles of lower specific gravity flow with the bulk of the water, out the vortex finder. Mineral particles of higher specific gravity flow with little water out the apex. A more technically e:mct description of the functioning of the water-only cyclone can be found in previous publications noted in the references.The water-only cyclone was invented and refined by J. Vis man, formerly of the Canadian Mines Branch staff, between 1958 and 1965. The first industrial application noted in the literature was when it was introduced as a cleaner for fine coal in 1962. Since 1970 the water-only cyclone has become a common separation apparatus in many Canadian and foreign coal processing plants. The only other mineral industry application known to the author is in separation of gold bearing heavy minerals from sand<'>. The potential does exist for other applications and this area deserves to be investigated more thoroughly than it has been."

Jan 1, 1989

By Rod Abbott

High Definition Scanning (laser scanning) is a proven technology that is accurate to within 6mm in 50m (¼? in 150?). It can capture in excess of one million 3D point measurements in an average 2 hour scan. It has numerous applications including brown-field retrofits, bridge measurement and analysis, verifying as-built conditions, and crime scene investigation. We most commonly use it for plant design to capture current site conditions, so as to prevent interferences and problems before construction begins. All vital information is captured in the first site visit, which limits the need for extra field trips.

Oct 1, 2010

By D. F. VanDine, H. George

"The possibility of spoil pile failure at the Kara Kara bauxite strip mine, Guyana, South America, is of major concern to the mine operators. The current mining technique requires the continuous operation of an 11 ms bucket capacity walking dragline on top of 18 metres of freshly spoiled uncompacted overburden material consisting of varying mixtures of kaolinitic clay and quartzitic sand. A field biased geotechnical study of undisturbed overburden and corresponding spoiled material has identified site-specific, non-linear correlations between vane shear strength, standard penetration resistance and spoil pile composition. Readily available geological exploration borehole logs has enabled a composite clay isopach map of the entire mining property to be drawn and critical areas to be zoned according to expected slope stability. Stability has been assessed using simple hand calculation techniques. Use of the resulting stability map provides the mine operators with a means of forecasting the need for appropriate preventative measures at varying stages of mine development, throughout the life of the mine.A similar investigation procedure could be employed at many presently operating and future strip mines.IntroductionThe Kara Kara bauxite stripe mine is located at Linden within the bauxite belt of Guyana in South America. The mining property covers a total area of 88 hectares of flat to gently sloping ground of which some forty per cent is being actively mined or being preparatorily stripped of overburden, prior to eventual mining (George and Gordon, 1979). The regional climate is tropic and humid. Temperatures vary from 16°C to 38°C and yearly rainfall averages 2600 mm, with at least 55 per cent of this precipitation occurring during the &apos;wet season&apos; months of May to July and December to January."

Jan 1, 1983

By M. Hashemzadeh

The efficiency of water use is a top priority for the global minerals industry, especially in regions with limited freshwater supplies. In these areas, the freshwater shortage has prompted mining companies to search for alternatives to freshwater sources. Seawater has been proven to be a potential water source for mineral beneficiation and metal extraction processes. This study compares chalcocite leaching behavior with ferric chloride to that with cupric chloride. We carried out leaching tests with a highly pure chalcocite sample in jacketed reactors under fully controlled pH and solution potential. The effect of chloride concentration, oxidant concentration, and temperature on copper extraction was quantified in both cupric and ferric chloride systems. In the ferric chloride system, increasing ferric concentration showed a positive effect on the first stage of chalcocite leaching. In the second stage, increasing temperature markedly enhanced copper extraction. In the cupric chloride system, chloride concentration presented a considerable effect on both the first and second stages of leaching, while temperature had a remarkable effect only on the second stage. The findings of this study would be beneficial to mine operations aiming to replace fresh water with seawater for heap leaching of chalcocite. INTRODUCTION Mineral processing operations/plants are normally operated adjacent to mines which are often located in remote and arid area, such as northern Chile, southern Peru and Australia with limited access to fresh water (Liu, Moran, & Vink, 2011, 2013). Water scarcity in these areas has prompted mining companies to invest in sustainable technologies to reduce the water use and/or increase the water use efficiency. One of the current sustainable approaches in mineral processing operations is to replace fresh water with seawater. Seawater is now being increasingly used for mineral beneficiation and metal extraction processes (Hernández et al., 2015). Another application of seawater could be for heap leaching of copper secondary sulfides, mainly chalcocite. However, the high concentration of chloride ion in seawater may significantly affect leaching kinetics of copper sulfide concentrates and ores (Watling et al., 2014). Therefore, it is essential to develop a fundamental understanding of the leaching of chalcocite in chloride media.

Jan 1, 2019

By J. N. Cram

"The comments given are to help allay generally accepted ideas that the handling of arsenic as arsenic-trioxide (As2o3J in and from off gas pyrometallurgical operation fumes is difficult, hazardous and expensive. It need not be any of these things if the basic and rather unique chemic3l and physical properties are understood and taken care and advantage of through present day technologies. These particular characteristics are:-(1) As2o3 sublimes and re-condenses, at a relatively low temperature;(2) As2o3 is, for practical in-plant purposes, insoluble in water at ambient temperatures and quite soluble in water just below the boiling point;(3) residual suspended and dissolved As 2o3 can be removed from water by complete dissolution with very little sulfuric acid, followed by the addition of small amounts of ferrous sulfate and calcium chlorate, with oxidation to the ferric and arsenite state and precipitation of an insoluble ferric calcium arsenate, thereby lowering the As2o3 content of solutions to acceptable levels. Even lower levels of non-toxic forms of arsenic solids and residual As2o3 in the water solutions can be attained by also using phosphate, and lime, along with the above.A background re past arsenic processing methods, present day operations, plus predictions re future trends, and hazards, are outlined."

Jan 1, 1979

By G. A. Maki, P. J. Fullman, R. G. Roden

"In October 1984, Rocanville Division began using a stacking system to handle potash mill tailings. Previous to this date, mill tailings were slurried to the top of the tailings pile and allowed to debrine while flowing down the pile. With the new stacking system, slurried tailings are fed to mobile stackers. The stackers consist of cyclone packs to debrine the tailings and drag conveyors with screw discharges to deposit the tailings onto the existing pile. This paper deals with the various aspects of the project from conception to its present state.IntroductionPrevious to 1984, when the stacking project was first implemented, potash mill tailings were handled as follows. Mill tailings were first debrined to approximately 65010 solids using a cyclone cluster. The cyclone underflows were then introduced onto a vacuum scroll filter table. Here the tailings were further debrined and discharged into the disposal tank where the tailings were reslurried with reclaim brine and pumped to the tailings disposal site. At the disposal site the slurry was discharged onto the tailings pile and by a natural settling process the tailings were debrined with the brine ultimately collected in the reclaim brine ponds. The shape and profile of the tailings pile was controlled by building salt dykes to control the flow of the discharged tailings slurry. As the tailings pile grew in height, booster pumps were added to the disposal system."

Jan 1, 1990

By Jr. Fackler

The ionization potentials of gaseous Group 11elements are similar, with Au(0) being 1.5 eV greater than the next highest member of the group, Cu(0). The ionization potentials are all very much greater than the alkali metals, making these ?coinage? elements rather unreactive to chemical oxidation. Ionization from the first oxidation state shows a different pattern, with Ag(I) being the most difficult of the Group 11 ions to lose an electron. Gold(I) is noble and only normally oxidized in the presence of strongly coordinating ligands such as thiols or cyanide. Gold(I) compounds are 2-, 3- and 4- coordinate, with 3-coordinate species generally showing visible photoluminescence under UV excitation. Dinuclear Au(I) compounds with strongly coordinating S or C ligands can be oxidized to form isolable metal-metal bonded Au(II) compounds which are often readily isolable. Many have been structurally characterized. T he ease with which electrons are lost from closed shell dinuclear sp ecies (with anti-bonding M-M interactions) increases when metalmetal bonded compounds are formed. T his observation was made by our group with oxidative-addition studies of dinuclear gold(I) ylide complexes. It was superbly demonstrated recently by Cotton?s group who reported the isolation and characterization of a dinuclear closed shell transition metal species which is more readily oxidized than cesium. Trinuclear Au(I) pyrazolates, TR(pz), carb eniates, TR(carb), and benzylimidazolates, TR(bz), are well known and undergo electron loss through oxidative addition forming Au(I,III) mixed valence species and ultimately trinuclear Au(III) species. Au(II) species are absent from isolation in these oxidations. These carbeniates and benzylimidazolates also are excellent bases for metals ions such as Tl(I) and Ag(I). The acidic, neutral trinuclear compound [Hg(C6F4)3]3 also interacts with these bases. We have also shown that the neutral organic pi acids C6F6 and TCNQ form stacked pi-acid pi-base products with the trinuclear Au(I) compounds. In this paper, the structure of the octafluoronaphthalene acid-base product will be described. It displays a feature not observed previously in that the product is photoluminescent with a bright yellow emission. The 3.5 ms lifetime is very long and reminiscent of the long lifetimes observed by Balch for the stacked methyl,methoxy Au(carb). The electrochemical oxidation of tetragold(I) clusters, [Au4(form)4] have been studied in 0.1 M Bu4NPF6/CH2Cl2 at Pt working electrode at different scan rates. Three waves are obtained at 0.75, 0.95, and 1.09 V vs Ag/AgCl at scan rate 500 mV/s. The potential of the three reversible waves is independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two waves. These tetranuclear species app ear to be effec tive catalyst precursors for the oxidation in air of CO. Introduction. The electronic structural relationships of the coinage elements and the alkali metals are similar in the sense that each have a [closed shell]ns1 configuration, yet their ionization energies (Table) and chemistries are clearly vastly different. The Group 11coinage elements have an underlying nd10 level immediately below the ns1 level. Unlike the alkali elements, ionization leaves the filled d electron shell the next accessible for further ionization. The coinage elements are all relatively ?noble?, much less reactive to environm ental conditions than the alkali metals. With the coinage elements, oxidation becomes very much dependent upon the types of ligand s availab le to bo nd to the ionized state.

Oct 1, 2003

By M. Choy, A. Kadiayi, E. Magdzinski

"Design of engineering controls to limit occupational noise exposure rely on accurate calculation inputs. Sound in mines can carry considerable distances. Mine ventilation engineers rely on noise propagation calculations to estimate silencer performance criteria for key mine fan installations that are often in proximity to occupied areas of a mine and can remain in service for decades. The blasted and rockbolted walls of hard rock mining tunnels have unique acoustical properties. Underground testing in an operating metal mine in Sudbury, Canada was performed and results processed to characterize noise propagation in mines, with the goal of improving the accuracy of noise calculations.INTRODUCTIONAs mine operators continue to improve and promote workplace safety, addressing noise at fixed infrastructure locations is observed as increasingly common. Underground fans are important to consider in this context, as they are typically loud, in proximity to occupied and sensitive workplaces, and operate nearly continuously. Predicting noise propagation from ventilation fans within underground mines has long been a challenge, with few available resources documenting acoustical properties as calculation inputs. Other factors in addition to rock face absorption properties include tunnel geometry and distance from the fan, which play critical roles in characterizing the noise level at any given point away from the fan. By understanding and establishing methods to better predict noise dissipation along underground mining tunnels, engineers can design noise controls with a greater degree of precision and confidence to effectively protect workers from over exposure to noise.This paper investigates classical methods of predicting reverberant room and direct field noise propagation. These prediction methods are then compared to noise measurements taken within the Fraser Mine of Glencore’s Sudbury Integrated Nickel Operations (Sudbury INO) Measurements were taken at a depth of ~881 m (2,889 ft), along an ~300 m (984 ft) long blasted hard rock mining tunnel. The noise along the mine tunnel resulted from the intakes of two 900 kW (1,200 hp) ventilation fans with a combined exhaust capacity of 300 m3/s (630,000 cfm)."

Jan 1, 2019

By M. Maldonado, P. Olivares

"A submersible sensor for real-time gas holdup measurement in the collection zone of industrial flotation machines is introduced. The working principle is based on the generation and measurement of a pulp flow using a gas-exclusion cell immersed in the aerated slurry. The gas exclusion cell consists of a variable-area open vertical tube designed to be filled only with pulp by preventing gas bubbles entrance. The higher density of the fluid column within the cell generates a downward flow of pulp; the rate of this flow is proportional to the gas holdup outside the cell. The gas holdup measurement is achieved by tracking the velocity of the pulp flow leaving the gas-exclusion cell, using a magnetic flowmeter. Construction details of a prototype and its testing in two- and three-phases are discussed.INTRODUCTIONFlotation process optimization consists of finding and maintaining operating conditions that maximize flotation performance measured in terms of recovery and grade. The selective separation of mineral particles proceeds in two interactive zones where different and simultaneous phenomena take place: in the collection zone, the valuable particles are separated by collection on the surface of bubbles, while in the froth zone, the bubble-particle aggregates are gathered, drained to remove entrained particles, and taken into the concentrate stream. The cell overall performance, which can be determined from proper stream sampling, is a function of the recoveries in the individual zones. These zone recoveries cannot be independently measured nor calculated from operating variables. Progress in the assessment of these recoveries has been slow because on-line and reliable sensors to measure properties of the drastically different dispersions existing in both zones are not available.In the case of the collection zone, it has been demonstrated that the recovery of hydrophobic particles on the surface of bubbles, considered as a process with first-order kinetics, correlates with the bubble surface area flux (Finch et al., 2000; Hernandez, et al., 2003; Lopez-Saucedo et al., 2012). Bubble surface area flux (bubble area generated per unit time and cell cross-sectional area), is a variable affected by gas flow rate, bubble size distribution, and frother type and concentration. Gas holdup (volumetric fraction of gas dispersed in the slurry) is also affected by the same variables, and as such, carries information on the interacting variables that define the performance of the process. Therefore, a correlation between gas holdup and bubble surface area flux was expected and demonstrated (Finch et al, 2000), and since gas holdup is easier to measure as no bubble size is required, it has the potential to be the basis of a cell control and optimization strategy if a continuous sensor is available."

Jan 1, 2016

By G. P. Gu

The in-service 90/10 cupro-nickel tubes in a water-chiller system suffered from severe corrosion damage during their relatively short service life causing unexpected down time. In addition to downtime, the environmental risk associated with losing refrigerant was also a concern that initiated this investigation, Microstructural investigation using SEM and electron microprobe indicated that pitting corrosion had resulted in local nickel depletion, During the corrosion process, copper appeared to have re-deposited around the corrosion pits accelerating the local corrosion.

Jan 1, 2005

By Donald A. Cranstone

Donald Cranstone holds B.Sc. (Honours) and M.Sc. degrees in Geology from the University of Manitoba and a Ph.D. in Economic Geology from Harvard University. He has worked as a mine geologist, a provincial geological survey geologist and as a senior exploration geologist. He joined what is now the Minerals and Metals Sector of Natural Resources Canada in 1971, where he has been a commodity specialist for gold, for copper and another 28 metals. He is a senior mineral economist, currently engaged in analysis of mineral exploration and discovery success in Canada and of the future of the Canadian mining industry. Abstract This paper examines the history of Canadian non-petroleum mineral production. The outlook over the next 25 years, for mining in Canada and in each province and territory, is reviewed. The outlook for mining in Canada and in most provinces/territories is favourable, but problems seem likely in a few jurisdictions unless new orebodies are brought into production. In terms of exploration potential, Canada consistently ranks among the top three countries in the world. Over the last eight years, Canada has consistently been second only to Australia as a destination for exploration investment. For the first time, Canada is ranked in terms of total mineral production, including coal and construction materials, relative to all the countries of the world including countries of the former communist bloc.

May 1, 2001

By A. Ghahremaninezhad, E. Jorjani, A. Riahi, Islamic Azad University, B. Nazari, H. Hani, Z. Manafi

The presence of a high iron concentration, 9.1 g/L, in the raffinate of the Sarcheshmeh copper heap bioleach process led to the formation of various types of jarosite, (K,Na,NH4,H3O)Fe3(SO4)2(OH)6, on the heap mineral surfaces. This study probes iron removal from the raffinate using a bio-oxidation process based on A. ferrooxidans bacteria in the presence and absence of jarosite seed. The jarosite seed was biologically synthesized using A. ferrooxidans bacteria. The effect of solution pH (1.5 to 2.5) and jarosite seed dosage (0 to 15 wt.%) on iron removal was examined. It was demonstrated that the concentration of iron ions present in the raffinate decreased from 9.1 g/L to 2.5 g/L with the addition of 10 wt.% jarosite seed at pH 2 and 130 rpm mixing rate at 32°C. Three different types of raffinate including (1) native raffinate containing 9.1, 3.4, 5.7 g/L of total, ferric and ferrous iron, respectively, (2) bio-oxidized raffinate in the absence of the jarosite seed containing 8.5 g/L total iron (mainly ferric with negligible ferrous), (3) bio-oxidized raffinate in the presence of jarosite seed containing 2.55 g/L total iron (mainly ferric with negligible ferrous) were used in mesophilic, moderate thermophilic and thermophilic bioleaching processes. The results of the flask tests showed that the highest copper bioleaching recoveries of 9.4, 49.4 and 90.8 % were achieved using raffinate (3) with mesophilic, moderate thermophilic and thermophilic bioleaching processes, respectively.

Jan 1, 2016

Adaptive processing is often related to the mineral composition of the mining block currently processed. The portions of waste, ore and secondary product minerals considered are always positive and typically sum to 100% (i.e. a composition). A typical solution to predict block averages of spatially dependent quantities would be block kriging. However, kriging is based on spatial correlations and it has been repeatedly shown that correlations of compositional data are spurious and blurred by the constant sum constraint. Aitchison (1982) proposed a general solution for compositional problems, based on transforming the compositional data to a set of logarithms of ratios of components, and analysing the transformed scores. The transform is chosen to be invertible to ensure that no information is lost in the process. This methodology avoids spurious correlation problems and ensures coherence between results obtained with different subcompositions. Pawlowsky-Glahn and Olea (2004) adapted the approach for point-support geostatistics, allowing the prediction of point compositions from spatially neighbouring data, without the artefacts induced by standard multivariate cokriging. Unfortunately upscaling the results of this approach with block cokriging is not straightforward, because of the nonlinearity of logratio transforms. Furthermore, we have to consider those nonlinearities created by the dependence on the block composition of extraction efficiency and processing costs of the possible processing choices. This paper proposes a solution for predicting the conditional expectations of the benefit of processing the block with each processing choice using geostatistical simulations of the local values of the composition and the resulting block integrals. The computation for a large number of blocks can be done efficiently using Cholesky decomposition. The approach also allows the calculation of prediction errors for expected compositions and expected benefit at almost no additional computational cost. Such compositional approach is necessary, for example when processing choices depend on proportions of certain minerals after other components have been removed; or if processing alters the composition in a multiplicative way, by partially removing a portion of some components.

Aug 1, 2013

By S. Pauly, U. Kühn, J. Eckert, I. Kaban, G. Wiehl, F. Silze

In the present work, the effect of Ga on the wetting behavior of the Cu-rich braze filler CuGa10 (wt.%) on the steel 304L was investigated. For this, the macroscopic and microscopic effects governing the wetting of pure Ga, pure Cu and CuGa10 alloy (wt.%) on the austenitic steel were analyzed and compared. Contact angle and surface tension measurements were carried out by means of the sessile drop technique and, in addition, the phase formation at the interface was determined. Pure liquid Ga spreads on 304L, which supposedly is related to the formation of intermetallic Fe-Ga phases growing into the liquid Ga. Depending on the annealing time, FeGa3 and Fe14.5Ga12 were identified. In contrast, CuGa10 as well as pure Cu show secondary wetting on the steel surface. Especially, liquid Cu prefers to spread laterally and vertically along the grain boundaries of the steel substrate. In spite of rather similar mechanisms, CuGa10 wets 304L steel at lower rate than pure Cu above the liquidus temperature.

Jan 1, 2014

By M. S. Moats, C. M. Campbell

Samples of a high impurity (90.05 wt. % Cu, 4076 ppm Pb, 1939 ppm As and 635 ppm Bi) commercial copper anode were characterized and then electrorefined in a laboratory scale cell. Anode inclusions were examined using backscatter mode scanning electron microscopy and energy dispersive spectroscopy. Hundreds of inclusions were measured for size, morphology and composition. Commonly found inclusions were copper oxide (Cu2O), complex oxides (Cu-Pb-Bi-As-O) and copper selenides/tellurides. The weight percent of lead and arsenic increased with increasing inclusion size up to 4- 5 microns. During electrorefining, starter sheet ductility was negatively impacted by thiourea addition. The importance of arsenic (V) concentration on the electrolyte concentration of bismuth was observed. INTRODUCTION Copper electrorefining is a commercial process used to produce the majority of the world’s refined copper. During this process, impure copper anodes are dissolved electrolytically, and high purity copper is deposited on cathodes. As the anodes dissolve, the impurities either accumulate in the electrolyte or report to solids that form on anodes surfaces or at the bottom of the refining cell. These solids are called slimes. Slimes contain precious metals and are collected for further processing. Slimes are also an important outlet for problem impurities such as lead, antimony and bismuth. The electrorefining process is operated in such a way to encourage the deportment of these elements to the slimes. Impurities in copper anodes have been studied extensively by Chen and Dutrizac (1990, 1993 and 2005). The most common impurities found in modern copper anodes include: Ag, As, Au, Bi, Fe, Ni, O, Pb, Sb, Se, Sn and Te. Impure copper anodes are produced by pyrometallurgical methods and have purities ranging from 97.7–99.7% Cu (Moats et al., 2019). The composition ranges of commercial copper anodes from the 2019 worldwide tankhouse survey are given in Table 1. The concentrations of anode impurities vary widely dependent on the source material and prior processing steps. Based on the work of Chen and Dutrizac, both gold and silver are predominantly found in solid solution within the copper grains while a minor amount of Ag can be found in Cu2(Se/Te) inclusions. Nickel is entirely soluble within the copper grains up to anode compositions of 2500–3000 ppm Ni; above which NiO and kupferglimmer phases are formed (Chen & Dutrizac, 1990). As, Bi, Pb and Sb are found in solid solution within copper and within oxide inclusions typically found along grain boundaries. Oxides are formed due to the presence of 0.13-0.18 wt. % O (Chen & Dutrizac, 1990). This is because during solidification of the cast anodes, impurities are enriched in the liquid phase as the copper grains nucleate and grow. The inclusions form from the last liquid to freeze, which is typically along grain boundaries (Wenzl & Filzwieser, 2007; Wenzl, Filzwieser, Mori & Pesl, 2008).

Jan 1, 2019

By Arsenio Enriquez, Adrian Deneys, Ryan Walton, Jenny Esker

NOx emissions at the Rio-Tinto Kennecott Copper (RTKC) smelter, near Salt Lake City, Utah, are regulated to a compliance emission limit at the Main Stack of 15.9 kg/hr on an annual rolling average. The paper discusses RTKC efforts and improvements, particularly related to the anode furnace operations, since the Smelter modernization in 1995 to comply with the air quality approval limit. This includes replacement of gaseous ammonia to Steam-Gas Refining (SGR) system during the copper reduction stage, upgrade anode furnace oxygen-fuel burner from Praxair’s Stabilized Jet (S-J) to Jet Lance (J-L) technology, development and implementation of operational best practices and continuing to investigate and evaluate NOx control technology and strategy in the industry. In early 2016, changes to Praxair J-L Burner technology on both anode furnaces, utilizing wider lance spacing, was adopted and further improved NOx emission levels well below the compliance limit. INTRODUCTION Since the establishment of the Clear Air Act in 1970, the Environmental Protection Agency (EPA) has been regulating emissions of nitrogen oxides (NOx) to reduce impact on public health and the environment (USEPA, CAA, USEPA, NAAQS). As a requirement of the Clean Air Act, the EPA evaluates the standards for NOx and criteria pollutants on a periodic basis and as a result, standards have been revised and ultimately reduced over time (USEPA, CAA, USEPA, NAAQS, UDAQ, SIP). To remain competitive with changing regulations and in conjunction with Rio Tinto environmental standards for continuous improvement, the RTKC smelter has been motivated to research and implement NOx control strategies. NOx health and environment impacts NOx refers to a group of seven compounds including the most common, nitrogen dioxide (NO2). (USEPA, NO2). The EPA enforces both short-term (1-hr average) and long-term (annual average) standards for NO2 to protect against associated respiratory system impacts. Short-term exposure of elevated NO2 concentrations can aggravate respiratory diseases and lead to symptoms such as coughing, wheezing or difficulty breathing while longer exposures may contribute to the development of asthma and potentially increase susceptibility to respiratory infections. (USEPA, NO2) Additionally, NOx is necessary in the formation of ozone and particulate matter less than 2.5 microns (PM2.5). Ozone concentrations can negatively impact lung function and in some cases, contribute to chronic obstructive pulmonary disease. (USEPA, Ozone) The particles associated with PM2.5 can reduce lung capacity and aggravate heart conditions. (USEPA, PM2.5) For all NOx related pollutants, children and the elderly are generally at greater risk for the health effects. (USEPA, NO2, USEPA, Ozone, USEPA, PM2.5)

Jan 1, 2019

By W. Andrew Falls

Although we have yet to reach the midway point in the decade, the copper concentrate market has already witnessed some of the most volatile swings in history, moving from record high treatment and refining charges in 1991-92 to historic lows, in real terms, during the past year. What has been the cause for such volatility? By and large the swings can be attributed to factors of supply and demand in the "custom" copper concentrate market. For example, two relatively recent events which had a major impact on the supply-demand balance were the shutdown of the Bougainville copper mine in Papua New Guinea in 1989 due to rebel insurgency and the startup of the La Escondida mine in Chile in 1992. The first event, threw a balanced to slightly surplus concentrate market into a substantial deficit, forcing treatment terms down as smelters, caught short by the loss of concentrate supplies scrambled to cover their positions. The second event, brought over 300,000 mt per year of new copper in concentrate to the market, more than reversing the losses from the Bougainville shutdown. In combination with other additions to mine capacity via new mines or expansions, the custom concentrate market moved into a huge oversupply in 1991-92 and many mines found themselves unable to place uncommitted tonnage. But even this event was quickly overcome by the use of underutilized capacity at non-traditional buyers, such as those in the C.I.S., Zambia, or those which were not traditionally buyers of custom materials. All of this has happened in the space of five short years, a mere snapshot in the history of the market. I'll return to these points a little further on, but first I would like to review the fundamentals which govern the copper concentrate market.

Jan 1, 1995

By William H. McCracken, William G. Holroyd

"The People&apos;s Republic of China could very well be considered the largest untapped mineral and metal resource in the world. The proven reserves of antimony, barite, bauxite, fluorspar, graphite, lithium, magnesite, mercury, molybdenum, phosphate, pyrite, rare earths, talc, tin, titanium, tungsten, vanadium and zinc are among the largest in the world.Any company involved in the purchase or supply of industrial raw materials has undoubtedly followed the phenomenal growth of some of the Chinese mineral commodities, where growths in production of more than 200010 have occurred during the past ten years, for commodities like barite, cement, gold, gympsum silver and talc. Others, like bauxite and phosphate, experienced production increases in one year alone of over 45%, from 1986 through 1987!A popular rationale in the United States during the past two years has been the acknowledgment by Professor David Calleo, of Johns Hopkins School of Advanced Studies, that ""America is not sinking-the rest of the world is rising"". While we recognized this rise to be that of economic power for Japan, Korea, Brazil, Taiwan and, more recently, the newly-combined Germanies, China has also successfully completed her own modern five year development binge. But with each boom there is also a bust, and the start of the 1990sfor China shows signs of economic distress. China posted a budget deficit equivalent of US$1.9 billion in 1989 coupled with official inflation at 18010. Projections for 1990 are for US$1.8 billion deficit and inflation as high as 24%. However, government spending in the first seven months of the year climbed 16.4%, outpacing an 11.6% rise in revenue. Spending increases have been related to the government policy to keep prices on domestic goods artificially low, through subsidies, and to bailout inefficient state companies."

Jan 1, 1991

By M. I. Abbas, M. A. Shahin, M. S. Ahmed

"The influence of annealing of galvanized steel (galvannealing) on its corrosion kinetics in a saturated solution of Ca (OH)2 has been studied by means of the polarization resistance method.Galvannealing heat treatment was carried out at 450°C and 550°C for varying times. Annealing at 450°C for 24 hr or at 550°C for 5 hr showed the highest corrosion potential (Ecorr) ~= - 400 m V/ SCE as well as, the lowest corrosion current density (icorr ~= 3 mA.cm-2, while Ecorr and icorr of the unheated specimens were ~= - 1400m V/SCE and == 20 mA.cm-2, respectively.Polarization curves were also obtained for the as-received galvanized specimens together with the galvannealed ones.INTRODUCTIONHeat treatment of galvanized steel (i.e . galvannealing) is carried out at a temperature range of 450°C to 550°C for a time sufficient to convert the free zinc coating to an alloyed one consisting of layers of iron-zinc intermetallic compounds. Table I is a review of the properties of the Fe-Zn intermetallicphases while Figure I is a reproduction - of the Fe-Zn equilibrium phase diagram taken from Hansen.Several authors have studied the formation of intermetallic phases through the interdiffusion of Zn/Fe couples. Their results confirmed the stability of intermetallic phases that could be shown up on the outer surface as a result of galvannealing of galvanized steel.Bernick and Sievertv"" investigated the processing of galvan nealed steel. They found that the galvannealed coating with the best forming qualities consisted of a mixture of Zeta phase and Eta phase."

Jan 1, 1989