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By A. Carbonari

In order to gain competitiveness and compete at a global level, construction companies should improve their efficiency. The problem is even more relevant in the construction field, whose work processes find it hard to evolve towards new automated methods and techniques in the management field. For that reason, this paper suggests how construction companies could apply new technologies to implement automated management of environmental hazards. Based on a survey regarding the environmental risks presently experienced in construction sites, noise and dust were considered two of the main hazards. So in this paper a networked system for real time remote monitoring of the spatial distribution of dust in construction sites was developed. Such a system would relieve builders from the commitment of on-site surveys, allowing for a continuous monitoring of the site conditions and of the real exposure of each worker and pass-by to the pollutants generated by construction works. The main system requirements considered are: easy to deploy, reliable, as accurate as needed to be able to send real-time warnings and store a good estimation of the real exposure to which involved people have been subject to. So far the research produced a prototypical hardware for dust monitoring made up of wireless sensors which can be easily deployed on site. The sensors were calibrated by means of laboratory tests, where their measurements were compared with those collected by means of highly accurate instruments, which were taken as a reference. Thanks to these experiments, calibration curves for the sensors were worked out, showing also the measurement range of the sensors.

Aug 1, 2013

By T. Grammatikopoulos, A. Jordens, C. Gunning

"Exploration activity for rare earth element (REE) deposits (i.e., alkaline complexes, carbonatites) has increased significantly in the last decade. A number of deposits have been evaluated around the globe. However, new mines have not been commenced in the last few years with the exception of Mount Weld (Lynas) and Mountain Pass (Molycorp).Resource estimation of REE can follow similar guidelines to other metal projects. However, the inherent mineralogical characteristics of the REE deposits, despite their complex nature, have been generally overlooked by many exploration companies. These include variability of the ore, liberation and association of the REE minerals, and grain size, all of which can affect the processing of the ore. Each deposit appears to be different in terms of matrix and REM (rare earth minerals). Light REE bearing minerals such as allanite, monazite, bastnaesite, synchysite, and HREE bearing minerals such as fergusonite and xenotime can vary widely in composition, grain size and association (e.g., carbonates or hard silicates). On the other hand, although not really REM, zircon, Zr-silicates, titanite, fluorite, apatite, and in some cases many other common silicate minerals can carry trace to significant concentrations of REE.The evaluation of REE deposits should include an appropriate mineralogical characterization in order to quantify the REM, distribution, liberation and association by quantitative mineralogical techniques (i.e., QEMSCAN, MLA, TIMA and others); chemistry of the REM by electron probe micro analysis (EPMA), Laser Ablation ICP-MS or ToF SIMS.These techniques provide valuable data for geological purposes such as: defining quantitatively, the variability and distribution of the REM; differentiating between LREE and HREE zones to delineate ore; and metallurgical purposes to predict minerals/REE behaviour during processing. The lack of a comprehensive mineralogical characterization often leads to the wrong processing path and ultimately affects the elemental/mineral recovery."

Jan 1, 2016

By C. B. Ndimande, C. Ntsele, M. Lisso, L. Arlow

"In the processing of UG2 platinum ore, stirred milling technologies are dominating regrind applications that require grinding the particles to P80s’ in the region of 45 µm. For this application stirred mills are 30–40% more energy efficient and require a smaller foot print compared to traditional tumbling mills. In this work a study was carried out using a batch pin mill and three scales of Stirred Media Detritors. A laboratory scale pin mill, a pilot scale Stirred Media Detritor with an installed power of 18.5 KW and two industrial scale Stirred Media Detritors in continuous operation, with an installed power of 355 KW and 1,100 KW were used. The industrial scale SMDs were in the secondary grinding section of a mill floatmill float (MF2) UG2 processing plants. The tests were focused on assessing the effect of feed rate and percent solids on power consumption and product fineness at lab scale, floatation response of the SMD product at pilot scale and on an industrial scale, the effect of feed rate on energy consumption and product fineness. The measurements obtained were feed flow rates, mill power and from the samples cut, particle size distribution of both feed and product. Specific energy was observed to increase with increasing percent solids over the 30wt% to 80wt% studied. Floatation response tests of the pilot scale SMD products show improvement in grade. Specific energy and reduction rations are observed to decrease with an increase in feed rate.INTRODUCTIONThe purpose of comminution in most mineral processing applications is to liberate the valuable minerals from gangue so that they can be recovered in subsequent separation stages. Most precious and base metal plants treat low grade fine-grained ores which require a higher degree of size reduction to yield the necessary degree of liberation (Partyka & Yan, 2007). Many authors have shown that the relationship between product size and grinding energy consumption is exponential, the finer the product from the comminution device, the higher the energy consumption (Gao & Weller 1993; Napier-Munn, Morell, Morrison & Kojovic, 1996; Jankovic, Valery & La Rosa, 2003). The suggested reason for this kind of relationship is that smaller particles have fewer flaws and higher strength than larger particles. Particles with fewer flaws and higher strength require higher energy for breakage to occur. One of the challenges most plants face is that of efficient energy utilisation in the liberation of the mineral from these complex ores. Conventional tumbling mills are not energy efficient in fine and ultra-fine grinding applications because some of the energy is spent on moving the charge and does not go directly into breakage. Stirred mills have been found to be about 30% to 40% more efficient and require a smaller foot print compared to traditional tumbling mills for regrind applications that require product size with P80s’ in the sub 45 µm regions (Radziszewski & Allen, 2013). Stirred mills are able to produce fine product because they can achieve a high number of stress events per unit time and volume compared to tumbling mills (Kwade, 1999a). To minimise energy usage without compromising product quality, the mining industry has adopted stirred milling technologies for fine and ultra-fine grinding (Radziszewski & Allen 2014; Kwade, 1999b). The south Africa platinum group metal (PGM) industry alone had over 40 stirred media mills installed by 2011 (Rule, 2011). Of that 40, 13 were in the ultra-fine grinding (UFG) application and the rest in main stream inert grinding (MIG)."

Jan 1, 2016

By S. Shokri

The increasing size and complexity of mega construction projects result in having several geographically distributed stakeholders, collaborating with each other to successfully deliver the project. Electronic Product and Process Management Systems (EPPMS) are recently emerging to facilitate the collaboration between stakeholders, reduce the surprises and issues, and improve the project productivity. These are commercially successful but evolving systems. An important component of EPPMS is the Interface Management System, which aims at formalizing and automating the communication channels between stakeholders. An interface is generally considered the link between construction elements, phases, or stakeholders. An interface Management System (IMS) involves five iterative steps: (1) Interface Identification, (2) Interface Documentation, (3) Interface Transferring, (4) Interface Communication, and (5) Interface Closing. A fundamental part of step 2 is recognizing different roles in dealing with interfaces. Each stakeholder is assigned a different role, such as responsible, accountable, consulted, and informed. In a mega project, several thousands of interfaces exist with complex relationships between stakeholders. Therefore, identifying stakeholders with higher responsible roles has been requested as useful information to the project owner in dealing with some of the project risks. After the interfaces are determined, and the responsibilities are allocated, the critical stakeholders are identified using the centrality concept in Social Network Analysis. The critical stakeholders can be determined at the highest level, considering all types of interfaces, as well as for each specific type or discipline-related interfaces. The proposed methodology is applied on a hypothetical offshore project with over 500 interfaces. In fact, this project is a simplified representation of a real scale Liquid Natural Gas project. In order to reduce the complexity of calculations and clarity of explanations, the simplified case study is used. By implementing IMS in mega projects, different parties not only formalize the communication between each other, but also gain better visibility concerning their roles and responsibilities. In addition, the owner benefits from analysing the complex relationships between stakeholders to further identify critical ones, along with other criteria like package cost, stakeholders? experiences, etc.

Aug 1, 2013

By Mariam Melashvili, Chris Fleming, Rene Jackman

"A study was undertaken to develop a flowsheet for treating a high grade silver/gold ore body by cyanidation, CCD and Merrill Crowe precipitation, with tailings detoxification to meet stringent limits for cyanide and thiocyanate concentrations in the final discharge. In one of the flowsheets examined, free cyanide in the final leach liquor was recycled to the mill where it was hoped that it might react beneficially with fresh ore to reduce the cyanide makeup by an equivalent amount. However, laboratory results suggested that most of the cyanide recycled to the mill reacted with iron forming a soluble ferrocyanide complex. This would have had a negative impact on cost, not only because the cyanide recycled to the mill could not be claimed as a credit, but also because the presence of ferrocyanide in the final tailings meant copper sulphate had to be added to the SO2/air cyanide detoxification process to precipitate the iron cyanide. In an alternative flowsheet that was examined, recycling of cyanide to the mill was abandoned, and this allowed the milled slurry to be pre-aerated in a single mixing tank before cyanidation. During alkaline pre-aeration, any ferrous ions that are generated in the mill are oxidized to ferric ions, which, unlike ferrous ions, are inert in cyanide solution. This significantly reduced cyanide consumption and lowered costs in the detoxification of the tailings. In this paper, the cost implication of these two circuits is compared.INTRODUCTIONMost of the gold that is produced by hydrometallurgical processes is recovered by cyanide leaching. The reason for that lies in the superior thermodynamic stability of the gold cyanide complex and the favorable economics this confers on the process (Fleming, 2014). However, the gold in most of the gold-bearing ores processed is a very minor component, and therefore, the leaching response is often dominated by that of the host minerals.Many gold ores treated by the cyanidation process contain iron minerals. Cyanide reacts readily with some iron minerals forming ferrocyanide as one of the compounds. Ferrocyanide is stable when solutions are exposed to air and does not retard the dissolution of gold. In fact, it has been claimed that potassium ferrocyanide in the presence of oxygen is a weak solvent for gold (Hedley & Tabachnick, 1958). The main problem with the formation of this compound is the consumption of cyanide. Ferrocyanide contains six molecules of cyanide for each atom of iron {Fe(CN)64-} so the wasteful consumption of cyanide is greatly increased by its presence. Thiocyanate is also often produced during the reaction of certain iron sulphide minerals with cyanide, and contributes to the wasteful consumption of cyanide. In addition, environmental regulations in certain countries demand that thiocyanate be removed from the tailings, and this adds significantly to the cost of tailings treatment."

Jan 1, 2016

By Daniel Gendron, Luc Morin

"Concentrate sampling is a growing concern in the world's mining and smelting industry. The main modes of transportation for concentrate to the smelter are by truck or rail car in a bulk form, thereby limiting access to sample extraction equipment. In many cases, concentrate is shipped to a smelter by several suppliers therefore requiring individual manipulation of different customer samples in a safe and reliable manner. The Heath & Sherwood Bulk Product Sampler offers this feature as well as an economical and effortless way of obtaining samples in rail cars or truck boxes.In 1994, Noranda Metallurgie in Rouyn-Noranda, Québec purchased a self contained Bulk Product Sampler to extract samples directly from inside rail cars before unloading the concentrate. After testing and comparing the results with the conventional sampling method, the bulk product sampler proved to be a practical and advantageous solution for concentrate sampling both for the customer and smelter. Since its installation at the Horne smelter in Rouyn-Noranda, the Bulk Product Sampler has been steadily used on rail cars which contain concentrates from around the world."

Jan 1, 1996

By D. Kao, J. Gogal, S. Humphrey, T. Byrne, M. Davoodi

"High total and dissolved uranium values were noted in the process water at the Cigar Lake Operation (CLO) during early production start-up period, whereas significant levels of dissolved uranium had not been observed previously at similar operations. The excess dissolved uranium resulted in higher demands on the water treatment plant, along with higher operating costs, environmental risks and some unrealized revenue potential. A species balance indicated that uranium was leaching into solution in the grinding, dewatering, and storage circuits under normal operating conditions. Jet boring, water recycle, ball milling, and the use of Pachuca tanks for ore storage results in a highly oxidative environment, which is favourable to leaching.This paper will outline the testwork performed to identify the conditions under which the uranium leaches into solution and to determine required conditions for uranium precipitation. Maximum uranium leaching was found to occur under normal operating conditions (pH ranging from 7.0 to 8.5); testwork indicated that both lowering and raising the pH can significantly reduce the uranium leaching. Analytical results combined with the batch scale testwork indicate that the uranium solubility is associated with carbonate species in the ore. Uranium precipitation was maximized at pH values greater than 10.5 or less than 6, corresponding well to carbonate leaching and precipitation values from literature. Higher precipitation efficiencies were noted at high pH ranges.As a result of this work, a pH control system has been implemented in the Pachuca storage vessels and thickener prior to water treatment plant on a trial basis. Caustic soda is recommended for pH control due to ease of operation, economic viability and material requirements and downstream constraints."

Jan 1, 2016

By D. T. A. Symons, M. M. Kapnistos

"Gravity profiles were established over five known Middle Silurian pinnacle reef s in Lambton County, southwestern Ontario. The profiles were approximately 3 km long, with stations every 60 m. Four fairly recent technological developments were used which now make the gravity method relatively efficient and inexpensive compared to the techniques available two decades ago. These are: (1) a La Coste-Romberg model G gravimeter to measure the gravitational attraction with a sensitivity of 0.01 mgal; (2) a Sokkisha model B-2 semiautomatic engineers level to measure the station elevations with an accuracy of 0.5 cm; (3) a Huntec FS-3 hammer reflection seismograph to determine the overburden thickness to an accuracy of ± 7%; and (4) a modern microcomputer to process the data sets and mathematically filter the gravity values. Thus, two men can measure and analyze approximately 1 km of profile per day and obtain the residual gravity profile to an accuracy of ± 0. 05 mgal. Positive gravity anomalies of 0.17 to 0.72 mgal were observed along all five profiles that approximately delineate the dimensions of the known pinnacle reefs, which have an average height of 120 m, diameter of 1500 m and depth to top of 575 m. The relative ease of the gravity survey method makes it a cost-effective technique for hydrocarbon exploration in southwestern Ontario. IntroductionPinnacle reefs are important sources of oil and gas. Although the pinnacle reefs in southwestern Ontario are small, they may contain commercial pools of oil and gas because of their proximity to refineries. They are also useful for subsurface storage of gas to meet the winter surge in gas demand.At present, geophysical exploration for new pinnacle reefs is done primarily by relatively expensive seismic methods, which are also limited in southwestern Ontario by prohibitions on blasting. Gravity methods of exploration were attempted more than two decades ago in this region. (Pohly, 1954); however, the level of technology at that time made the method marginal in sensitivity and quite expensive. Several subsequent developments- gravimeters with greater sensitivity and operating ease, ""self-levelling"" levels for elevation control, hammer seismic reflection units for determining overburden thickness and portable microcomputers for efficient data analysis-have significantly improved the precision and cost effectiveness of the gravity method. Five known pinnacle reefs were selected in Lambton County, southwestern Ontario (Fig. 1), to test the effectiveness of integrating these developments to locate and define additional reefs. Isolated reefs were chosen to avoid the problem of the gravity effect s of one reef interfering with those of a neighbouring reef. The surveys were facilitated by choosing reefs with a concession road passing directly over them ."

Jan 1, 1980

By M. J. Dry, G. B. Harris

"This paper presents basic chemistry and operating conditions for the hydrolysis of ferric chloride into solid hematite and gaseous hydrogen chloride, and shows how this unit operation can be applied in chloride hydrometallurgy to regenerate strong hydrochloric acid and reject iron without also rejecting valuable metals such as nickel, copper and cobalt. Two examples are used to illustrate the hydrolysis technology and compare it to existing technology. The first is the regeneration of spent steel pickling acid, comparing hydrolysis to conventional pyrohydrolysis. The second example is the processing of a hypothetical low grade nickel laterite, comparing the novel chloride hydrolysis route to conventional sulphate HPAL technology.INTRODUCTION Whilst, in many respects, the control and removal of dissolved iron from chloride leach solutions can resemble the manner in which it is done in sulphate systems, chloride chemistry additionally offers the ability to achieve the same objectives in different ways (Harris, 2014). Conventionally, iron is oxidised to its ferric state (if necessary) and then precipitated with a base, usually magnesia where the feed is a laterite and lime where it is a sulphide, since calcium will precipitate sulphate formed during leaching. One method for controlling iron is to form FeOOH, either ß-FeOOH (akaganéite), a-FeOOH (goethite), or a mixture thereof (Fillipou and Choi, 2002). However, if akaganéite is formed, the precipitate will contain a significant chloride component (as high as 7% Cl), leading to chloride losses and difficulty in satisfactorily disposing of the residue. Washing chloride from akaganéite is almost impossible due to the propensity of the solids to undergo peptization. The conventional approach requires the addition of a base, but it is based to some extent on controlled supersaturation precipitation (Demopoulos, 2009), which produces a more uniform and crystalline material and is far more attractive than, for example, the turboaeration process proposed by Great Central Mines in their chloride copper process (Raudsepp & Beattie, 1986)."

Jan 1, 2016

By J. G. Cullain

In conjunction with the over-all goals of energy conservation at Inco Metals Company, a program of improvement in compressed air utilization was established. Air flows were monitored and compared to calculated requirements to establish efficiency by area. With the cooperation of area management, measures were implemented to reduce nonproductive usage. At the operation, annual savings in power consumption alone were 80,000 dollars. The program is being extended to other mine areas within the Division.

Jan 1, 1979

The mining industry has generally been slow to apply ion exchange processes to hydrometallurgical applications even if ion exchange offers an ideal solution for a particular problem. Two notable exceptions are in gold and uranium recovery. The largest application of ion exchange in the metals processing industry has been the use of resin-in-pulp (RIP) for gold recovery as an alternative to activated carbon. Iron is a ubiquitous impurity in hydrometallurgical solutions. In many cases, bulk removal of iron from the process solutions is accomplished by precipitation. However, precipitation for iron control is often accompanied by losses of base metals by co-precipitation. Increasingly, the option of ion exchange for removal of smaller amounts of iron from process solutions has been favoured. A number of applications have been developed and proven at the commercial scale for the removal/control of iron from a range of metal processing solutions. This paper provides an overview of the application of ion exchange for iron removal from a range of metal processing operations, including Cu, Ni and Co solutions. A number of case studies are provided which review operational and resin regeneration strategies and the impact upon the commercial operation of metal processing with improved iron control.

Jan 1, 2006

By Avinash Kandalam, Markus Reuter, Jörg Kleeberg, Michael Stelter

The Top Submerged Lance (TSL) technology has obtained significant importance in the pyrometallurgy industry for nearly four decades. One of the advantages of TSL furnace is its high reaction rate, which is caused by splashing and turbulence of the melt. In contradiction, this phenomenon stands as a barrier for conducting experimental investigations to validate the simulation models. The highly turbulent and splashing environment in the TSL furnace is caused due to the immersion of the lance into the slag layer and thus the effect of the flame structure is directly related to the splashing, turbulence, reaction kinetics and life-span of the lance. Moreover, the material properties such as viscosity, density and the surface tension will also influence the flame structure. As a first step to understand the flame structure, attempts are made to generate a stable flame of the lance in an open environment. INTRODUCTION Top Submerged Lance (TSL) technology was invented during the 1970s at Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia by Floyd and Denholm. This technology was later commercialised and currently, there are about 100 TSL plants around the world commissioned by various licence holders such as AUSMELT (Outotec) and ISASMELT (Xstrata- Glencore Technology). Copper is the most produced non-ferrous metal followed by lead and zinc, see Hunt (2005). Today, a wide range of primary, secondary, and complex recycling materials are used as a feed material in the TSL, Alvear et al. (2010), Kaye et al. (2008). The working principle of TSL technology lies on inserting and submerging a lance from the top of a vertical cylindrical chamber into the slag layer. The lance is considered as the heart of the furnace, where the air and fuel are transported through two concentric tubes and are mixed in a combustion chamber, which is approximately 7 cm from the tip of the lance (considering the pilot-scale TSL furnace at the Institute for Nonferrous Metallurgy and Purest Materials - INEMET). The TSL furnace is very flexible with the type of fuel, feed material and the air input. The fuel can be natural gas/heating oil/fine coal particles and the air could be enriched with oxygen (Figure 1). The general mechanism of the TSL furnace lies on feeding the material from the top of the furnace and the material is pulled into the molten bath due to the high turbulent atmosphere, which results in high reaction rates. The thermocouples installed in the furnace (i.e. in the ceramic linings) allow the operator to know the temperature of the melt. For example, in the case of copper production the tapped material (i.e. matte/metal) can be transported to a settler for further processing or directly used.

Jan 1, 2019

By R. G. L. McCready, R. O. van Everdingen, M. Kalin, R. van Everdingen

"This paper is based on data generated between October, 1986 and October, 1989, during the implementation of an Ecological Engineering close-out for a zinc mine in Northern Ontario, where 690000 tonnes of tailings contain 41.1% pyrite and 4.1% pyrrhotite. The objective was to determine rates of sulphide oxidation and iron precipitation in the tailings. Those rates are relevant for the assessment of the long-term effectiveness of biological systems employed in the removal of heavy metals from contaminated drainage issuing from tailings.Data were collected on the topography and stratigraphy of the tailings basin, subsurface temperatures and groundwater levels, and chemical analyses were made of water samples collected from a number of piezometers. The thickness of unsaturated tailings varied widely between individual piezometer locations; annual maxima ranged from 0.67 m to 3.55 m, and annual minima from 0 to 2.68 m. Sulphate concentrations ranged from 36 mg/L to 20180 mg/L; iron concentrations from 0.36 mg/L to 9938 mg/L; and zinc concentrations from 0.33 mg/L to 1123 mg/L.The geochemistry of the piezometer samples suggests that some of the initial Fe content, resulting from metal sulphide oxidation, is subsequently precipitated in the tailings pile and, possibly, in the underlying unconsolidated sediments, probably in the form of iron-hydroxide and Na-jarosite. Other metals such as Zn may be co-precipitated with Fe. The discharge of a portion of these metals to the environment would be delayed by this process. Some of the initial sulphate may also be lost from solution, probably by precipitation of gypsum; approximate saturation degrees for gypsum ranged from -3.27 to +0.47. The precipitated minerals will somewhat decrease the porosity and permeability of the tailings.Sulphide-oxidation rates, calculated using the analytical results and the estimated amount of annual recharge at the tailings site, average 0.0057 mol/kg/yr. Calculated iron-precipitation rates average 0.000386 mol/kg/yr. It is concluded that the characteristics of seepage from mining wastes may change with time, reflecting the solubilization of precipitated secondary minerals."

Jan 1, 1992

By K. Bunney, R. Pleysier

The deportment of a suite of elements through representative gold ore processing unit operations in cyanidation has been investigated. Chromium and lead are not soluble in alkaline cyanide solutions. Arsenic, antimony, cobalt, molybdenum, selenium, tellurium and vanadium are soluble, but typically do not adsorb onto activated carbon to any appreciable extent. Silver, copper, cadmium, mercury, nickel and zinc to varying extents report along with the gold to the carbon eluate. Cadmium, mercury and zinc can report to the carbon regeneration kiln off-gases. Strontium is soluble and adsorbs on carbon where it remgins.

Jan 1, 2011

By Dieter Birk

"The Atlantic Coal Institute illustrates the potential for high technology employment in Maritime Canada, by using local talent and the latest equipment to address a national market. Since I983, contract research for industry and government has generated 31 man-years of high-tech employment, added $2.3 million to the local economy and contributed new technology for Canadian coal. Industry now has access to new procedures for coal minerals analysis, pyrolysis, and geochemistry applied to industrial problems of exploration, beneficiation, conversion and combustion.Research at the Institute is market-driven, based on cost recoveries from contracts. The financial performance to date exceeds that of similar industrial research institutes in major cities and demonstrates that small isolated laboratories are cost-effective. Economic renewal of Canada's resource industries will require increased R&D which in turn can be a source of local employment and pride. Small research teams are more efficient but require an enlightened policy of contracting-out by big business and big government."

Jan 1, 1987

By J. H. Nantel, J. F. Archibald

"The presence of radon from uranium-bearing ores, waste and from backfill material introduced underground to provide ground support, work platform and waste disposal functions, requires that ventilation controls be established to maintain safe working level concentrations. One approach has been developed at Queen's University to quantify radon and radon daughter source level s and to estimate ventilation requirements necessary to maintain these safe levels.Knowledge concerning the sources of radioactive contaminants and their production quantities is of value for planning and design stages of ventilation control systems. For any given mine layout, radiation level estimates may be forecast and modified by ventilation network design where excessive production quantities may exist.Behaviour of Radon Gas in MinesRadon gas, produced from the decay of Ra-226 in a host medium, will diffuse through porous media. In areas adjacent to mine workings, radon will be liberated into the mine atmosphere. The rate of radon emanation is proportional to the rate at which radon is produced within the host material (a function of the ore grade of U308) , to the radon concentration gradient in the host pores and to the diffusion properties of the material.The radon source concentration is determined by the rate at which Rn-222 is produced by the decay of Ra-226, and by the emanating coefficient (E), or fraction of the radon which escapes from the source matrix and is free to diffuse through the pore spaces."

Jan 1, 1984

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 SangHyeok Han

Selecting the best possible cranes and identifying spatial conflict-free locations on sites can result in productivity and safety improvements for large-scale industrial construction projects. In the current practice, experienced lift engineers select cranes based on the heaviest lift and/or the largest lifting radius of the identified crane. This practice is relatively time-consuming, and optimization of the crane?s use and location is also difficult. There are many factors which need to be considered during the crane selection process, a reality which further complicates the process. This paper presents a framework which aims at developing a decision support system to enhance the crane selection process and collision-free path planning for large-scale construction projects. This paper utilizes an innovative crane selection matrix in order to establish a process for optimized crane selection for construction projects. The study considers more than 40 different factors in order to reduce time and improve safety for crane operations. Following finalization of crane type (mobile crane versus tower crane), a visualization model to simulate crane operation and identify collision-free crane operation paths is proposed. This process can assist project managers to plan the lifting process more effectively and efficiently. A case study-based approach was utilized to demonstrate the proposed methodology. The methodology was tested in the planning and construction process for boiler house structures in Mannheim, Germany. The project entailed numerous challenges: one of the major tasks was to lift a 102-ton load on the top of the boiler structure through crane collaboration; space limitations on site also presented several challenges related to crane selection, location, and operation processes. Based on the project constraints, the proposed crane selection framework, and the visualization models, two tower cranes were selected and successfully implemented in the case study.

Aug 1, 2013

By Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014

By BARRY BANNATYNE

Ombrotrophic Sphagnum peat bogs have a characteristic signature on both colour injrared film (750 nm to 3,000 nm response) and Daedalus injrared line-scanner images (thermal infrared 3 to 5 microns and 8 to 14 microns response). This remote sensing method was used to survey bogs in southeast Manitoba to delineate targets for surface exploration. Target bogs all have a surface growth of Sphagnum; underlying dead Sphagnum ranges from 1 to 6 m thick. Large Sphagnum reserves exist in the Caribou cluster of bogs, and in /979 a bog first identified by infrared sensing was brought into production.

Jan 1, 1984