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By M. Niinae, F. Nakahara, T. Kawamoto, T. Suzuki

"MgO was chosen as an As(V) immobilization agent and a series of immobilization experiments was performed to obtain insights into the behavior of As(V)and MgO during leaching tests. Our experimental and modeling results demonstrated that As(V) immobilization by MgO consists of the following steps: (i) an increase in soil pH, (ii) desorption of As(V) from the soil, and (iii) the re-immobilization of As(V) by MgO/Mg(OH)2particles. Regarding the behavior of MgO, the modeling results showed that when the MgO dosage was 25 mg MgO/4g-drysoilor less, the majority of MgO was used to increase pH, and less than 1% of MgO was used to sorb As(V), which was consistent with the result of leaching tests showing that a high level of As(V) was leached at the MgO dosages. On the other hand, when the MgO dosage was above 25 mg MgO/4g-drysoil, the percentage of MgO used for As(V) sorption increased up to 35%, and correspondingly, the As(V) leaching level decreased to below 0.01 mg/L As at an MgO dosage of 75 mg MgO/4g-drysoil.INTRODUCTIONOne of the major arsenictransport pathways causing groundwater contamination is the migration of arsenicfrom artificially or naturally contaminated surface soils. Therefore, in this study, the immobilization of arsenate (As(V)) in soils was investigated using commercial-grade magnesium oxide (MgO) as a potential cost-effective measurement to prevent the occurrence of groundwater contamination with As(V).With respect to the use of MgO for remediating As(V)-contaminated environmental media, MgO has been used in several studies to remove As(V)from water(Yu et al., 2011; Jia et al., 2013; Tresintsi et al., 2014). Although these studies demonstrated that MgO effectively removes As(V)from water in water-MgO systems, the behavior of As(V)in water-soil-MgO systems has not been evaluated in the literature, and several questions remain to be answered to comprehensively evaluate the use of MgO as an As(V)immobilization agent in soils. For instance, as is well-documented in the literature(Ford, 2002; Lenoble et al., 2002; Zeng et al., 2008), iron oxy-hydroxide (FeOOH) is one of the important adsorbents for As(V)in both natural and engineered systems. Therefore, it is anticipated that the presence of FeOOH in soils significantly influences the behavior of As(V)in water-soil-MgO systems and consequently, the immobilization performance by MgO. Another important question to be answered is the behavior of MgO during the immobilization treatment. In our previous studies (Suzuki et al., 2013a, 2013b), commercial-grade MgO was demonstrated to effectively immobilize lead and fluoride, and the immobilization effectiveness was indicated to last more than 100 years against the exposure to acid rain (pH 4.0). However, these studies focused on the behavior of contaminants. As a result, little is known about the behavior of MgO during the immobilization treatment. The lack of understanding of the behavior of MgO during immobilization treatment is one of the main concerns leading to relatively low public confidence in immobilization treatments."

Jan 1, 2016

By M. Roy, Y. Roux, R. McIvor

"La Compagnie Minière Québec Cartier at Port Cartier. Quebec, utilizes six parallel wet grinding open circuit ball mills to grind iron ore concentrate for the pellet making process. In an attempt to improve grinding efficiency, a mix of 605 25 mm (1 in.) and 405 38 mm (1 ½ in.) grinding balls was charged to mill D while the opposite mix was used in all the other mills. Because media costs were higher for mill D, it was necessary to find out if the smaller balls provided a net economic benefit. Therefore, a test program was undertaken to determine the relative efficiency of the charge in mill D compared to the other grinding mills. Mill F was chosen for comparative efficiency measurements.The first problem was to choose a suitable definition of grinding efficiency. In management's view, previous attempts to quantify milling performance using population balance modelling were ineffective because they were unable to relate breakage rate functions to grinding circuit economical in any meaningful way. Work index analysis was also not favoured because of a number of complicating effects, including the fineness of the feed and product streams and open circuit grinding.It was decided to adopt a recent innovative approach which had been successfully applied to closed-circuit ball milling. For ""functional performance analysis of ball milling"" (McIvor et al., 1990; McIvor et al., 1991), a size criterion is first chosen to define ""fines·' and ~'coarse particles"". In this case 45 microns (325 mesh) was chosen to distinguish fines from coarse material. The relative grinding efficiency of each ball mill environment would then be ~e cumulative grinding (disappearance) rate of coarse (plus 45 nucrons) material per kilowatt hour of energy applied to the coarse material in the mill, divided by the grindability (measured in the laboratory) of the coarse material in the mill feed.Because the disappearance rate of coarse particles is also the production rate of fines, the following equation can be written for the efficiency of the mill environment, Effe, as defined above:"

Jan 1, 1994

By S. Zakaria

"Inco's Automated Haulage Truck System (AHT) is a revolutionary automatic guided vehicle that performs all load, haul and dump operations without human intervention. The high level of sophistication and the short period it has been in operation has only allowed a select few Inco personnel to become familiar with the ART operation and maintenance. As an aid to operations an expert system using the knowledge gained from the experienced specialists was implemented in the field.The AHT operating and maintenance assistance expert system will reason through the information given, arrive at conclusions and give advice to operations, technical and management personnel. It will provide comprehensive real-time troubleshooting assistance for the hydraulic, electrical and mechanical subsystems of the ART. The ART expert system has many benefits to Inco which include increased skill levels of ART operations and maintenance personnel, reduction in ART downtime, standardization of troubleshooting procedures and reduction in ART operating and maintenance costs. In the future, the expert system application will be linked to SCADA (Supervisory Control and Data Acquisition), maintenance and statistical software to display current and historical trends of variables from a centralized historical database. As well, a wide variety of features will be integrated into the system including AutoCad drawings, graphics, photographs, voice and video capabilities."

Jan 1, 1994

By R. Carpenter, H. Muntanion, P. Kleespies, E. Flood, M. Tansey

Abstract - BHP Minerals discovered the Archean lode gold ULU deposit on the western margin of the High Lake Volcanic Belt in 1989. The greenschist to amphibolite facies mafic volcanic and sedimentary rocks on the property are folded into a 5 km-long anticline. There is a close spatial association of Au-As zones to the trace of this F2 ULU anticline. The largest of these auriferous zones, the Flood zone, is localized at the core of the fold. The southeast-trending Flood zone consists of several anastomosing lenses that have been traced for 435 m on surface. Overall, it dips steeply (70° to 80°) to the southwest and has been intersected to depths below 600 m. The hosting high-iron tholeitic basalt displays a lower amphibolite mineral assemblage of ferrohornblende + plagioclase + ilmenite with accessory quartz and epidote. Alteration minerals include biotite, chlorite, hornblende, actinolite-tremolite, and potassium feldspar (microcline) with minor calcite, epidote, tourmaline, and titanite. The highest gold values occur where brecciated basaltic wall-rock clasts are replaced by acicular arsenopyrite + quartz + K-feldspar. BHP Minerals completed 54,783 m of both exploration and resource development drilling before selling the ULU property to Echo Bay Mines in 1995. Development of ULU as a satellite deposit to Echo Bay’s Lupin mine began in 1996. A -15% ramp was extended to the 155-meter level, and 16,011 m of underground drilling were completed before the decline in gold prices forced a suspension of activities at ULU in August 1997. The current owners, Wolfden Resources Inc., drilled 18,569 m in 2004 to increase confidence in the resource blocks. Following this drill program, a revised resource calculated by an independent consultant determined that the ULU deposit contains an inferred/indicated mineral resource of 1,130,000 t grading 11.34 g/t gold (373,748 oz) to the 360-m level. The portal was re-opened in 2005 and a prefeasibility study is underway.

Jan 1, 2004

By K. Reinharter, J. Schmidl, D. Gregurek, A. Spanring

Copper smelting furnaces are typically lined with magnesia-chromite refractories, which are exposed to multiple and complex stresses. The selection of the processing route, furnace type and slag system will be dictated by the specific ore type available, this will determine the individual refractory wear. This paper evaluates the common refractory wear mechanisms as observed in the copper Peirce-Smith converter and in the copper anode furnace. The chemical factors include corrosion caused by fayalite type slag and sulfur supply, as well as, by Cu-oxide attack. Changes in the temperature during the furnace operation (thermal-shock) create stresses in the brick lining which can only be absorbed in limited extent. Mechanical factors include erosion, caused primarily by the movement of the metal bath, slag and charging material, as well as, stresses in the brickwork due to punching. Finally improper lining procedures can also effect the service life. All these wear parameters lead to severe degeneration of the brick microstructure and a decreased lining life. Therefore, a detailed investigation and understanding of the wear mechanisms through “post mortem studies” together with thermochemical calculations by FactSageTM software is an important prerequisite for the refractory producer. Based on these research results, combined with specific process knowledge, appropriate brick lining solutions for copper processing furnaces can be recommended. INTRODUCTION The refining of copper includes converting of matte or black copper into blister copper for final fire refining process in the anode section. Typically Peirce-Smith (PS) converters are in use. Other technologies include Hoboken Converter, TBRC but also Flash Converting Furnace and bath smelting furnaces (ISA, Ausmelt) (Davenport et al., 2002). For fire refining two types of furnaces are used – the rotary furnace type is dominantly used in the primary production route while secondary smelters tend to use hearth refining furnaces which are more suitable for scrap melting. Installed working linings are based on magnesia-chromite bricks but especially in the anode refining section the application of alumina-chromia bricks have become more popular in the recent years. It comes without saying that, to some extent, large variations in the slag composition can be observed from the data provided to RHI Magnesita during post-mortem studies of used refractory samples and this needs to be addressed properly during the selection process of refractory linings.77

Jan 1, 2019

By P. H. J. Mercier, M. Couillard

Aberration-corrected scanning transmission electron microscopy (STEM) allows for the nano-scale exploration of materials at unprecedented resolution and sensitivity. In this paper, we combine this approach with electron energy-loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDX) to analyze the carbon distribution in residual solids found in solvent-diluted bitumen product extracted from Alberta oil sands. Major components of these contaminant solids are ultrafine clays. Biwettable clays have been associated with the formation of solid-stabilized water-in-oil emulsion, which are known to increase the content of both water and mineral solids in the final bitumen product. We demonstrate that the residual solids present in bitumen product contain carbon intermixed with mineral particles of various size and shape. By probing the carbon content at the nanometer scale with the high chemical sensitivity of EELS, we provide direct evidence of carbon intermixing with clay platelets. This clay-organic association at the nanometer-scale will contribute to the biwettable, hydrophobic character of the platelets, and will therefore play a crucial role in the bitumen extraction process

Jan 1, 2014

By M. B. McClenaghan

"The Ontario Geological Survey completed a regional till sampling project between 1984 and 1988 in the Black River Matheson (BRiM) area of northeastern Ontario. The project was designed to aid mineral exploration in the area by documenting the Quaternary stratigraphy and by providing a database of till geochemistry. This paper summarizes the results from the sonic overburden drilling component of the BRiM project carried out in areas of thick drift (> 5 m). Results from till sampling in areas of thinner drift (<5 m) have been presented in a separate paper. Approximately 1100 till samples were collected from 225 sonic drill holes. For each sample, the non-magnetic heavy mineral (>3.3 S.G.) and fine (-250 mesh) till fractions were analyzed geochemically and visible gold grains were recovered by panning.Gold and other multielement geochemical data were plotted using proportional symbols to highlight anomalous areas and to demonstrate how to evaluate and interpret a very large geochemical dataset. Thresholds for identifying anomalous concentrations of Au in till samples, defined using the 95th percentile, are 1500 ppb and 12 ppb for the heavy mineral and fine fractions, respectively. The heavy mineral fraction of older ti1ls and to a lesser extent, Matheson Till, display a number of significant gold anomalies in the study area, which in a few cases, are associated with base metal anomalies. The vertical position of gold anomalies in Matheson and older ti1ls varies from directly on bedrock to several meters above the bedrock surface and can provide information of relative ice transport distances."

Jan 1, 1994

By J. Mizera, B. Adamczyk-Cieslak, K. J. Kurzydlowski, A. Dobkowska

"AZ31 is the one of the most popular magnesium alloy using in the modern industry. It is well known, that compared with steel, magnesium alloys posse better properties, such as light mass, high specific strength or thermal conductivity. It should be noted that their application is limited by poor corrosion resistance. In this work the corrosion behavior of AZ31 magnesium alloy as cast and after heat treatment were described with the use of testing in neutral salt spray atmosphere.To characterise corrosion resistance and describe layers built on the surface it was necessary to do the metallographic observations with the use of optical microscopy. After that influence of heat treatment for AZ31 corrosion resistance was examined. Measurements were conducted by electrochemical impedance spectroscopy (EIS) and by neutral salt spray tests in artificial atmosphere. Surface and cross section morphology after removal of corrosion products were observed with the use of scanning electron microscopy (SEM).The weight loss measurements show that there is no significant difference between alloys as cast and with following heat treatment.INTRODUCTIONMagnesium and magnesium alloys are popular in modern industry because of the low density and good formability. Magnesium alloys are described by few properties which have got significant influence for their application in transportation and electronics industries (Feliu & Liorente, 2015). Their wide application is limited by poor corrosion resistance. As it is well known Mg is one of the chemically most active metal. Corrosion resistance of Mg alloys depends on several factors, such as impurities, chemical composition or working conditions (Cheng, Qin, Wang, & Zhang, 2009). That all causes that there are many different ways to find well defined and good solution of magnesium alloys processing to improve their corrosion resistance.There are many different versions about the influence of aluminum on the corrosion resistance of magnesium alloy. It is known that intermetallic compounds such as Mg17Al12 due to ß-phase content plays the minor role for corrosion resistance. It is proved ß-phase acts as cathode and it has good ability to build passive layer in broad pH ranges. However it should be noted that mentioned behavior depend on size and distributions of ß-phase in the microstructure (Singh, Singh, & Das, 2015)."

Jan 1, 2016

By L. Beiza, L. Velásquez-Yévenes

Chalcopyrite is by far the most abundant copper sulphide on Earth, but it has proved to be problematic in its processing by leaching, mainly related to its refractory nature, slow kinetic rates of dissolution and the formation of an inhibiting product layer on its surface during leaching. This study is focussed on the electrochemistry of chalcopyrite dissolution in acidic chloride system, which has recently gained attention as a feasible alternative to conventional sulphate media for chalcopyrite leaching. It is well understood that chalcopyrite dissolution from mineral grains depends strongly on the solution redox potential at the mineral surface as well as the composition of the product layer that may form on its surface. The chloride ions in solution support the Cu(II)/Cu(I) couple as the primary oxidant, as they can form complexes with the cuprous ions formed, increasing the dissolution rate. Additionally, these ions increase the potential range where chalcopyrite can be oxidized. The chemical reaction that occurs on the surface of chalcopyrite in chloride solutions in the presence of cupric ions will be characterized and the coulometry of the reaction will be reported to understand what is happening on the surface of chalcopyrite. Electrochemical experiments have been carried out to investigate the behaviour of mixed potential by open circuit potential (OCP) measurement for 30 minutes using sulphuric acid at pH 1 under nitrogen at 25⁰ C. The effect of chloride was analysed at 0, 20, 50 and 100 g/L and cupric ions from 0 to 50 g/L. The potentials obtained were then used to carry out chronoamperometry tests for a period of 30 minutes in absence of cupric ions. The mixed potential did not show a significant difference with an increase in cupric concentrations in the absence of chloride. Increased mixed potentials and current densities were observed at higher chloride and cupric concentrations. Chronoamperometry tests at those potentials were used to construct a voltammogram trace which has the same trend as a normal cyclic voltammogram but with much lower current densities. INTRODUCTION As a result of the depletion of copper oxides, the leaching of copper sulphide minerals has become the focus of many studies. Chalcopyrite, (CuFeS2) which is the most abundant of copper minerals, has proved to be challenging to process via hydrometallurgy, mainly related to its refractory nature, slow kinetic rates of dissolution and the formation of an inhibiting product layer on its surface, during leaching.

Jan 1, 2019

By V. K. Srivastava1

Coal mine fires burn about 20?21 million tons of coal per year throughout the world, which not only results in loss of valuable coal reserves, but also cause serious environmental hazards over large areas. The famous Jharia Coalfield of Dhanbad, India is no exception; here a coal mine fire originally reported nearly a century ago is still continuing unabated in vast areas of the coalfield. In this paper, an attempt has been made to analyse high resolution multispectral thermal images of ASTER for mapping and delineating surface and subsurface coal mine fire areas of this coalfield. From the generated temperature gradient map, as well as from the surface temperature anomaly map, it has been possible to differentiate shallow and deep coal mine fire regions and other erroneous cultural features. It is observed that the coal fires are distributed mostly in the eastern part of the area, which has branched into two major coal fire zones: one along Lodna- Tisra-Bhulanbarari-Kujama-Jealgora Jharia and the other along the Kusunda-Kendudih area. The western fire zone is restricted in Dumra-Nadkhurkee-Jayramdih area. From ASTER thermal infrared data from 2006, the total affected area is estimated to be about 7 km2, of which the deep subsurface coal mine fire area is around 3 km2 and the shallow surface coal mine fire area is around 4 km2, as compared to 18 km2 coal mine fire area estimated in 1987 using Landsat TM thermal band data. In other words, the fireaffected region has decreased by about 50 % during the last 18 years. However, such decrease in coal fire area is seen in the central portion only, and has in fact increased in the south eastern parts of the Jharia coalfield. Study of Differential Interferometery images, generated from Earth Resources Satellite (ERS) synthetic aperture radar (SAR) tandem data has shown that the active coal mine fires are in general associated with low topography/subsidence areas.

Aug 1, 2013

The PEMAC Commitment to World Class Industry in Canada The Plant Engineering and Maintenance Association of Canada PEMAC is a national, not-for-profit industry and technical association for plant and facility maintenance, engineering and physical asset management practitioners and professionals. Founded mid 80?s in the last century PEMAC is a knowledge based organization that focuses on sharing knowledge with our members and the profession. We provide education and professional development programs and certification for maintenance practitioners and professionals. We develop, produce and participate in conferences, seminars and trade shows.

May 1, 2008

By J. A. Eisele, D. L. Pool

"The Bureau of Mines has developed a particle agglomeration technique to improve the flow of leaching solution through heaps of low-grade gold-silver ores which contain clays. Benchscale experiments and industrial practice have shown that the percolation rate of cyanide leaching solution is greatly enhanced by mixing the ore with Portland cement as a binder, moistening the mixture, mechanically tumbling to form agglomerates, and aging before heap building and leaching. A slight modification ofthe technique allows its application to precious-metal-bearing tailings, which cannot normally be treated by heap leaching because they are too fine. IntroductionMany low-grade gold and silver deposits and tailing materials from former mining operations in the western United States are potential sources for precious metals. These sources are too low grade or too small to support the capital cost of a conventional cyanidation plant but have stimulated the development of lowcost procedures, such as extraction of the precious metals by heap leaching with cyanide. The Bureau of Mines has investigated methods to improve the recovery ofgold and silver by heap leaching these low-grade materials.For heap leaching to be successful, the crushed and stacked ore must have good permeability so that uniform distribution of the cyanide leaching solution through the heaps can be achieved. Some of the most difficult gold and silver ores to treat by heap leaching are those containing excessive amounts of clays, or fines generated during crushing. Excessive amounts of slimes, generally minus 50-micrometre or 270-mesh Tyler sieve size particles, in the heap feed will slow the percolation of the leaching solution, cause channelling, or produce dormant or unleached areas within the heap, resulting in long leaching periods and low extractions. In extreme cases, the clays or slimes can seal the heap and cause the leaching solution to run off the sides of the heap rather than through it."

Jan 1, 1987

By S. M. Bulatovic, D. M. Wyslouzil

"This paper presents the results of a study of the effect of flowsheet configurations on metallurgical results and describes a general method for developing and optimizing flowsheets used in the treatment of massive sulphide ores. The flowsheet configuration can have a significant effect on recovery and selectivity between valuable minerals and gangue minerals. Placing of intermediate products within the flowsheet, positioning of various pretreatment units, such as conditioners or regrinding mills, and the ability of the flowsheet to cope with wide swings in the feed grade and composition are the major parameters that determine the optimum flowsheet configuration. The complexity of the flowsheet is largely a function of the ore itself and of the number of final, marketable products that have to be recovered from the ore. INTRODUCTIONTechnological ExpansionThe trend of past decades has been towards larger equipment and a better understanding of the chemistry of the flotation process. Despite appreciable progress in these areas little attention was given to the study of the actual configuration of the flowsheet, although the arrangement of the flotation equipment significantly affects the overall performance of the circuit."

Jan 1, 1989

By A. Putz, F. Vincent, A. R. Laplante

"This paper briefly reviews some of the gravity research done at McGill University and current Canadian operating practices, with emphasis on results of interest for operators. The following topics are addressed: security, economics, predicting recovery, circuit optimization, unit selection and final upgrading. Emphasis is placed on the Knelson Concentrator.The topic of security and economics are addressed jointly, in terms of the place of the gravity circuit in the mill flowsheet. Actual plant experience is drawn upon to identify potential problems and actual solutions.Predicting primary recovery is linked with a characterization of the ore, the choice of a circuit, and the fraction of the bleed used. Factors such as feed preparation, preliminary upgrading, fraction of recycle treated, ability to recover fines and location of the bleed are discussed.Final upgrading is achieved almost only by tabling and smelting. This can lead to fine gold recovery problems when more effective units are used upstream. Alternatives are discussed.IntroductionResearch on gold recovery by gravity over the past eight years has associated McGill University with a number of gold producers. This paper attempts to review the information gathered from a practical perspective. Some of the information was generated in McGill University's labs, some gathered at plant site, and some was shared by operators."

Jan 1, 1994

By Jacob Wood, Robert Matusewicz

The Outotec® Ausmelt Top Submerged Lance (TSL) Process has achieved widespread commercial acceptance over the past 40 years for the processing of copper, nickel, lead, tin, zinc and precious metal bearing feeds. The continual development and evolution of the technology during this period has resulted in a more intense smelting process with higher energy efficiency and lower operating costs. More recently, considerable effort has been invested in decarbonisation of the process through improvements such as increased oxygen usage, dry feed injection and use of low-carbon auxiliary fuels. This paper covers a number of these recent advances to the technology and highlights their impacts on energy consumption and CO2 emissions for a range of non-ferrous smelting flowsheets. INTRODUCTION Relentless demand for improvements in the profitability, safety and environmental performance of non-ferrous smelting plants has driven a continual development and evolution of processing technologies in this industry. In response to these demands, a number of bath smelting technologies have emerged over the past 40 years and have been implemented for the treatment of primary and secondary feedstocks. The Outotec® Ausmelt Top Submerged Lance (TSL) Process (henceforth Ausmelt Process) is one such bath smelting technology which has been widely adopted in a large number of greenfield projects and brownfield plant modernisations (Wood & Hughes, 2016). Emissions of CO2 from the production of non-ferrous metals represent approximately 4-5% of global totals (Rankin, 2012), comparable with the almost 10% attributed to iron and steel production. Despite significant improvements in the energy efficiency of modern smelting technologies (Coursol, Mackey, Kapusta & Cardona Valencia, 2015), primarily through increased oxygen usage, further innovation and development is still required to address their reliance on fossil fuels such as coke and coal. Transformation of the non-ferrous smelting industry to low-carbon technologies and process flowsheets is lagging behind the power and transport sectors, which have witnessed significant growth in clean/renewable energy technologies to reduce CO2 emissions and address the issue of anthropogenic climate change (IRENA, 2018; IEA, 2018).

Jan 1, 2019

By M. Takebayashi, K. Takenaka, S. Matsubara, T. Yoneyama

The cathode production of Toyo Smelter and Refinery, owned by Sumitomo Metal Mining Co., Ltd. reached 450,000 tons per year in 2016 with three tank houses. Niihama tank house commenced operations in 1919 with conventional sheet cathode technology. Approximately 100 years of operation experience and the technical development enabled that the current density of Niihama tank house and the Toyo tank house #1 increased to 320 A/m2. These operation techniques were utilized at the Toyo tank house #2 which started in 2005, and its current density reached up to 350 A/m2 with permanent cathode technology. In order to achieve high current efficiency under condition of 350 A/m2 operation at Toyo tank house #2, continued efforts had been made to verticality of anodes and permanent cathodes. To improve verticality of anodes and cathodes, reduction of short circuit ratio by changing the shape of the anode, optimizing the anode pressing machine and off-line process for rectifying the distortion of permanent cathodes was carried out. In addition, concentration control of electrolyte and expansion of Ni removing ability from the electrolyte prevented passivation. Finally, more than 96% of the current efficiency was stably confirmed. INTRODUCTION Today, Toyo Smelter and Refinery of Sumitomo Metal Mining operates three tank houses in Japan, namely, Toyo tank house #1, Toyo tank house #2, and Niihama tank house with a total capacity of 450,000 metric tons of copper cathodes. Figure 1 shows the trend of cathode copper production and the current density at three tank houses over the last 10 years. Cathode production by Toyo Smelter and Refinery reached 450,000 tons per year in 2016 with three tank houses.

Jan 1, 2019

By Yufeng Yao, Robert P. Lowell

Abstract - Conductive heat flow anomalies associated with hydrothermal sulfide mounds on the seafloor have been studied. Sulfide mounds tend to focus conductive heat flow because sulfide minerals have a greater thermal conductivity than country rock. The topography of the mound above the seafloor, however, leads to a reduction of heat flow, particularly near the center of the mound. Because the focusing effect is constant, whereas the topographic effect decreases with distance away from the center, the focusing effect dominates toward the edges of the mound. The magnitude of these effects depends upon the conductivity contrast and the height/radius aspect ratio of the mound. Conductive heat flow anomalies at sulfide mounds also result from fluid circulation within the edifice. For the active and relict mounds at the TAG hydrothermal field, which have an aspect ratio of approximately 0.3 and a conductivity contrast of 3, the heat flux through the center of the mound should be roughly 70% of the background heat flux. The maximum effect of heat flow focusing is to increase the heat flux by about 30% above background. By comparing these effects with conductive heat flow data at TAG, we find that advective processes dominate conductive heat flow at both the active and relict mounds. Advective circulation can also give rise to much larger lateral and vertical temperature gradients than would result from conduction alone.

Jan 1, 1999

By J. X. Guo, A. Pindred, J. Moore

"Two modified centrifugal flotation cells (CFC), Q2 and Q3 models, have been developed for froth flotation. The operating mechanism of Q2 uses a rotating bowl to create a centrifugal force on the feeding slurry. Froth concentrate is collected on the central top of the cell and tailing is discharged along the top edge of the rotating bowl. The Q3 utilizes a vertical rotating feed pipe to introduce the feed slurry into a stationary flotation column cell. A centrifugal force is also created by a rotating pipe for the feeding slurry. Froth concentrate floats over the cell and tailing discharges through the bottom of the cell. The centrifugal force causes the flotation recovery of fine particles from CFC to be higher than from the conventional cell. The major operating variables of CFC are the rotating speed, air flow rate into feed slurry, and slurry feeding rate etc. Flotation tests have been carried out on synthetic mixtures of galena-silica and chalcopyrite-silica, as well as some natural base metal ore samples. Parallel tests were also conducted on a conventional flotation cell. The comparative test results demonstrated that both Q2 and Q3 have the advantage of higher recovery of finer than 10 µm mineral particles, which are very difficult for the conventional non-centrifugal flotation cell to recover. The grade-recovery curves produced from CFC are equivalent to or better than the conventional flotation cell. There is a potential in the future for the CFC to be employed in slime flotation.1. IntroductionA centrifugal flotation cell (CFC) was originally developed by Clean Earth Technologies [I] to separate oil from water and was subsequently applied in froth flotation. Figure 1 illustrates the design of the original CFC, in which a vertical feeding pipe is attached to the center part of a rotating drum and a stationary shell encloses it to direct the float froth and tailing discharge. The slurry flows down to the bottom of the spinning drum, gets in touch with a screen of air bubbles and then migrates outwards under the effect of centrifugal force. After the mineralized froth enters the rotating cell, it is pushed back to the inner surface. The overflowing froth is collected in the froth launder while the tailing slurry is discharged through orifices along the outer rim of the drum."

Jan 1, 1998

By M J. Daniel

Comminution is the science of size reduction of brittle materials. It is integral to mineral extraction and is one of the most energy intensive processes in the mining industry. There are a number of tests used to quantify the strength of ore, which are then used to size the AG / SAG mill in circuit design. The calculated energy utilized for breakage in these devices is based on the assumptions that the materials treated are of average shape and that the processing equipment is designed to break the ore as efficiently as possible under the given operating conditions. In drop weight tests, it was found that shape significantly influences the measured rock strength. Controlled experiments with variations in blends of rock shape show that mill throughput increases with the addition of weaker shaped rocks.

Jan 1, 2012

By N. Aydogan, H. Dundar, Å. Partapuoli, A. Fredriksson, P. Wikström, K. Tano, G. Adolfsson

The Autogenous milling of ores holds an increasing attraction as the focus moves towards reducing energy usage, both direct and embodied in grinding media. However, most of the early AG mills were converted to SAG for improved stability and increased throughput. This imposes a huge penalty in steel grinding media consumption. The LKAB iron ore operations in Sweden process highgrade magnetite through fully-autogenous milling lines to a final product P80 of about 45µm. The outcomes of P9O AMIRA research surveys, covering a wide range of mill fillings and throughputs and with different feed blends, are presented. Insights are provided on operational strategies, opportunities, the influence of feed size control and balancing the blend of competent gangue and softer magnetite. Areas of importance in the successful operation and control of energy-efficient autogenous circuits are highlighted.

Jan 1, 2012