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By A. Fahr, T. Byczkowski, M. Genest, C. Mandache

"Layered aluminum structures assembled with rivets are often found in aircraft fuselage. These structures are exposed to various mechanical loads and a range of environmental conditions that contribute to their ""aging"". The rivet holes are the source of stress concentrations and the location of crack nucleation and growth. Detection and sizing of second and third layer cracks under fasteners represent a major challenge for non-destructive evaluation (NDE) technicians. Electromagnetic methods are currently the most feasible NDE techniques that are capable of successfully inspecting such structures. However, different probe lift-offs, due to protruding rivets and paint coatings, or interlayer separations, due to sealant or air gaps, pose difficulties in detecting and sizing cracks. In addition, the use of conventional eddy current technique is limited due to the inverse relationship between the probe spatial resolution and its field penetrability. In this paper, we present an alternative approach that overcomes the previously mentioned shortcomings by using pulsed eddy current excitation and magnetoresistive sensor pick-up. Various signal manipulations are employed for defect detection and quantification."

Jan 1, 2006

By E. J. Burrough

MR. J. J. McIntyre (International Coal & Coke Company, Ltd., and McGi1livray Creek Coal & Coke Company, Ltd., Coleman, Alta): Mr. Burrough's excellent paper, Metallurgical Coals of the Crowsnest Area, seems especially timely now, when the need for developing iron industries in the west, as well as in the east, is receiving so much attention. His -thorough review of the 'coking' industry is an especially valuable contribution, along with which the following brief remarks on coking in the Crowsnest Pass area of British Columbia and Alberta may be in order. When the Crowsnest Pass line of the Canadian Pacific railway was built there were great expectations for the non-ferrous metal industry; quite a number of smelter's were al-ready in operation in British Columbia and the northwestern United States, and further expansion was confidently expected. The suitability of the medium-volatile coking coals of the Pass for making metallurgical coke had been recognized from the time the fields were first explored. By the time the mines were fairly well developed there was already a market to war-rant the building of coking plants, and a common belief that expansion of the market would require a large coking industry. The first coke production was from plants built by the Crowsnest Pass Coal Company, Ltd., at Fernie, B.C. in 1903, and the International Coal and Coke Company, Ltd., at Coleman, Alberta. These plants were followed by others built by the Crowsnest Pass Coal Company, at Michel, B.C., by West Canadian Collieries, Ltd., at Lille, Alberta, and by Leitch Collieries, Ltd., at Passburg Alberta, and by a plant at Hosmer, B.C.

Jan 1, 1951

By M. T. Ho, D. E. Wiley

The iron and steel industry accounts for almost 5 % of the total world CO2 emissions. Optimisation of the steelmaking process has led to significant reductions in the energy intensity to the point where it is now close to the thermodynamic limit. Further reductions are not likely to be achieved with efficiency improvement alone and will require the development of novel or breakthrough technologies. This paper will show the costs of implementing CO2 capture at direct atmospheric emission points for a number of iron and steel production processes. These include a conventional process, top gas recycling processes, the Corex and Hismelt smelt reduction processes and the Midrex direct reduction process. Depending on the point source emission, costs of capture with existing chemical absorption technology at iron and steel plants can be similar to capturing CO2 at pulverised coal fired power plants.

Jan 1, 2015

By Jochen Petersen

This paper gives an overview of the various strands of postgraduate and undergraduate training offered in the Department of Chemical Engineering at UCT. Since 2003 the Department is offering a formal postgraduate MSc programme in hydrometallurgical engineering aimed especially at graduate work-based engineers, with 5 weeks of intensive course work plus a research dissertation on a work-related project. This programme has now run 5 times over the years and produced some 20 degrees. The paper reflects on the experiences with running the course, especially the difficulties experienced with supervising industry-based external students. Furthermore, through the Department a graduate training program is offered for all junior metallurgists at a major South African minerals company. This 2-year program, which is currently on its 12th cohort, offers 1 or 2 week intensive blocks of course work alternating with longer stints where the candidates are based at various operations. Although primarily focussed on minerals processing, it has a significant element of hydrometallurgy in it and in recent years an advanced hydrometallurgy stream has been introduced. The paper reflects on the development of the program over the years, the benefits it has provided to the company as well as some of the challenges that remain. Finally the paper gives an overview of hydrometallurgy related undergraduate and research-only postgraduate MSc and PhD projects at the university. Some emphasis is placed on the recently launched South African Minerals and Metals Research Initiative (SAMMRI), a joint government-industry programme to support university-based research in the area of applied metallurgy.

Jan 1, 2014

By Thomas Kilpatrick

The liability created by building this railway is the great financial problem before the people of British Columbia at the present time. In dealing with the subject, I propose to divide it into three periods: The Past - The Present - and The Future. The Past The primary objects in building the railway were to provide an independent and direct route for the Grand Trunk Pacific railway into the city of Vancouver, and to open the central and north-eastern portion of the province.. This vast territory, almost one-half the entire area of British Columbia, has great wealth in fruit, agricultural, and grazing lands; timber, coal, water-power and minerals of all kinds, including some of the richest placer deposits in the world. Rivers and lakes teem with fish. Big game, including moose, elk, caribou, deer, grizzly and black bear, mountain goat and sheep, is plentiful and there is an abundance of small game and fur-bearing animals. In addition, its scenic attractions are unsurpassed in Canada. To develop these resources it was considered necessary to build a railway from south to north as a main artery of transportation and, if necessary, branch lines to carry heavy .shipments of coal or other commodities. Lighter freight may be handled by motor trucks from distant points to the railway.

Jan 1, 1925

By Franc R. Joubin, Donald H. James

"The Property of Rix Athabasca Uranium Mines Limited is in the Beaverlodge area of northwestern Saskatchewan. The mine is 7 miles by road north from the Lake Athabasca port of Bushell which is 250 miles north by aircraft or boat from railhead at Waterways, Alberta.The Rix property is a portion of the former DD 1 concession, obtained in 1949 from the government of Saskatchewan when private prospecting for uranium became permissible. The concession was prospected in detail during the 1950 and 1951 field seasons and a great many radioactive show-ings were discovered. Development and drilling were concentrated in two and later three of these areas, and by late 1952 enough ore had been indicated in the Leonard series and ""Smitty"" zone to justify underground development by adit-drift and shaft respectively.Four hundred feet of drift development on the Leonard No. 1 vein and the sinking of a two-level vertical shaft with related lateral development on the Smitty zone were completed in 1953. In April 1954 the Smitty section was placed in production at a rate averaging 100 tons per day, thereupon becoming the first privately owned post-war uranium producer in Canada. The ore is shipped for processing 12 miles by truck to the mill of Eldorado Mining and Refining Limited.Until recently all of the Company's production was drawn from the Smitty orebody. In April, 1955, ore production commenced from the faulted west extension of the Smitty structure, known as the Rix 62 zone, and from the Leonard No. 1 vein.The Smitty orebody (see Figure 2) is an intensely brecciated lenticular zone bordering both sides of the Smitty fault. The breccia areas are irregularly mineralized with pitchblende, very sparse galena, and pyrite in a gangue of feldspar, chlorite, calcite, and silica, all thoroughly soaked with fine-grained hematite to produce the locally-called ""red alteration"".Tenor of the ore currently being mined is classified information. The average grade estimated, prior to production, was 0.20 per cent (4.0 lbs.) U308 per ton."

Jan 1, 1949

By H. Clare Horwood

"Fractures and fracture zones containing veins and stringers of auriferous quartz in a quartz porphyry dyke are the principal structural features at the Howey and Hasaga gold mines. The 'break' containing the dyke was produced by a force from the northwest, the fractures in the dyke by compressive stress from the west.Both mines are in the north-central part of Heyson township, in the Red Lake area. They lie close to the southeastern side of the Dome granite stock. The Howey mine exhausted its ore reserves and ceased operations in November 1941. The Hasaga mine is producing at the present time (June, 1946).Mineralization was first discovered in the dyke in 1925 by the Howey brothers. Lorne Howey's discovery, which became the Howey mine, came into production in April, 1930; Ray Howey's find, which is now the Hasaga mine, started production in November, 1938.The total production from the Howey mine was 421,324 oz. gold and 144,253 oz. silver from 5,158,376 tons of ore hoisted ( 4,319,331 tons milled) during its 11 years of operation.The total production from the Hasaga mine from November, 1938, to December 31, 1945, was 124,434 oz. gold and 51,009 oz. silver from a total of 901,098 tons hoisted (721,361 tons milled).GENERAL GEOLOGYThe porphyry dyke containing the orebodies at the Howey and Hasaga mines lies a short distance southeast of the contact of a granite-granodiorite mass known as the Dome stock. The dyke fills a fracture trending N.65°E. in a tongue of Keewatin volcanic breccia that extends in a rather irregular manner into an elongate intrusive stock of dioritic rock known as the Howey diorite. The accompanying table presents the geological succession."

Jan 1, 1954

By L. Janku, G. Hancox, M. Villenueve, C. Massey

Wellington lies in a seismically active area 150 km from a subduction zone and in the vicinity of several active faults, which poses a risk to its infrastructure and inhabitants. One of these major faults, the Wellington Fault, runs through the centre of the city and across several lifelines, including the natural gas pipeline and the freshwater pipeline. The first settlement in the area was severely damaged in 1848, soon after its establishment, by an earthquake of approximate magnitude Mw 7.4 - 7.5 (Grapes, Little, & Downes, 1998). In 1855, another earthquake of magnitude Mw 8.2 generated by a nearby fault uplifted the eastern part of the current Wellington area and caused several landslides in the surrounding hills (Grapes & Downes, 1997). The Central Business District lies in the area of a sedimentary basin and partly on reclaimed land. Many residential areas, as well as some vital infrastructure, however, lie on or along the slopes in the surrounding hills. The bedrock in the area comprises predominantly the Torlesse greywacke of Permian – Late Triassic age. The greywacke is tilted to a steep angle, intensively faulted and fractured (Cook, 2001). Even though several studies in the past assessed the seismic risk in the area (e.g. Brabhaharan, Hancox, Perrin, & Dellow, 1994), the studies either focussed solely on the area of the sedimentary basin or based their assessment of the hilly terrain purely on slope morphology (slope angle). Previous studies have shown that slope shape and contrasting materials in the slope can amplify earthquake ground motions, such factors are typically called site effects (e.g. Geli, Bard, & Jullien, 1988). Any attempt to systematically quantify the site effects and consequent seismic response of the slopes and use it to predict the consequences of the next large-magnitude earthquake, has not yet been carried out. In this extended abstract we outline the methodology of a PhD research project, focussed on investigating the site effects on the slopes around Wellington and on creating representative numerical models of ‘characteristic’ Wellington slopes and materials. This extended abstract presents the methodology adopted for the assessment using the Te Ahumairangi Hill site as an example.

Jan 1, 2015

By P. A. Tichauer

Arbitration is a flexible method for dispute resolution that gives control to the disputing parties while still maintaining a clear and well-structured decision making process. It responds to the desires of the parties for a resolution that is fair, binding and enforceable and is guided more by pragmatism, efficiency, effectiveness and equality than by a need to comply with the legal procedures and practices of any single country or jurisdiction. Arbitration is particularly well suited for the resolution of disputes pertaining to international commercial agreements which are often present in the metallurgical sector. This paper provides a simplified outline of the features and advantages of arbitration as well as commentary regarding certain prerequisites in order for arbitration to be binding and enforceable.

Jan 1, 2015

By James J. Roettger, Robert J. Mitchell

"The results of a series of model stope pours designed to investigate working pressures on bulkheads during hydraulic pouring of classified tailings backfill are reported. Total bulkhead pressures and fill water pressures were monitored under the condition of a fully saturated backfill. Similitude of the model testing is discussed and equations are developed to estimate bulkhead pressures under prototype conditions. The model results show that good base drainage, combined with a bulkhead setback, can reduce the expected bulkhead pressures to values such that timber or concrete block structures should be capable of supporting a saturated backfill. Introduction Bulkheads are used in underground running operations to block drift openings in order that hydraulically placed sand backfill can be contained in stope pours. Whenever possible, the sand fill is designed to have sufficient percolation rate so that excess hydraulic transport water will gravity drain out through the bulk headed drifts. This avoids costly decanting systems. Early bulkhead design assumed that the bulkhead pressure could be as high as 0h = Hy where H is the fill height and ""y is the saturated unit weight of the fill (Thomas et al., 1979)(1). A typical design pressure for a 50 m fill height would be 1250 kPa giving a design force of 12,500 kN on a bulkhead located in a drift of 10m2 in area . Typical bulkheads were 1 m thick heavily reinforced concrete structures formed and poured into a notched drift. Not only were these expensive structures but the associated problems of inside drainage systems and curing time delays increased production costs. As experience with bulkheads for large bulk pours increased and fill pressure measurements became available [see, for examples, Libby et al., 1975(2), Askey et al., 1978(3)] , 'free drainage' timber and concrete block bulkheads were designed. Substantial savings have been realized using these types of bulkheads but greater engineering design and monitoring of backfill pours is necessary to ensure that backfill pressures do not exceed the bulkhead design pressures.The effective and total stress components of fill pressure, the engineering concepts associated with the 'free drainage' design and some detailed design considerations have been discussed by Smith and Mitchell (1982)(4) . It is important to the safe use of these designs, however, that the basic engineering concepts be demonstrated and communicated to those responsible for the day-to-day backfill operations. This paper describes and explains observations from a series of model studies designed to measure bulkhead pressures in a saturated fill."

Jan 1, 1984

By Elisabeth Kolar, Rik Catthoor, Frederik H. Kriel, Rossen Sedev, Gareth Hatch, Army Research Laboratory, Craig Priest, Scott Middlemas

"This paper reports solvent extraction of rare earth elements (REEs) carried out using a microfluidic device and considers the REE loading limit of the organic phase under laminar flow. The microfluidic device contacts aqueous and organic phase streams for a precisely defined contact time (subsecond resolution) and then separates them for offline analysis. Experiments are reported examining the effect of contact time on extraction. We focus on three REEs: one ‘light’ (Nd), one ‘mid’ (Dy), and one ‘heavy’ (Yb) REE, which are extracted using Cyanex® 572. It appears that loading limits may be locally exceeded in the organic phase near to the liquid-liquid interface, where third phase deposits are observed. Third phase formation was also observed close to the liquid-liquid interface in two-dimensional confinement, showing similar third phase adsorption on glass plates. It is also shown that, under microfluidic flow, a typical first ‘split’ between heavy REEs and light REEs can be carried out without exceeding loading limits.INTRODUCTIONMicrofluidic solvent extraction has emerged as a useful tool for studying extraction of metals in a mineral processing context (Ciceri, Mason, Harvie, Perera, & Stevens, 2013; Ciceri, Perera, & Stevens, 2011; Kriel et al., 2015; Mason, Ciceri, Harvie, Perera, & Stevens, 2013; Priest, Zhou, Klink, Sedev, & Ralston, 2012; Priest et al., 2011). The main advantages are the extremely well-defined and tunable flow behaviour, large surface-to-volume ratios, short contact times, and minimisation of sample and reagent amounts. Two main flow configurations have been studied to date: droplet-based and co-flowing streambased extraction. In the former, droplets are formed at a microchannel junction (usually a T-junction or flow-focusing junction) and flow downstream as plugs or ‘free’ droplets. In our case, stream-based extraction, the chip is a plate (often glass) with embedded microchannels (i.e. with cross-sections of tens of micrometres) that carry the aqueous and organic phases in contact without forming droplets. Thus, these chips play the role of a mixer in a conventional mixer-settler and phase separation takes place by branching the streams or collection in a vessel at the chip outlet. Stream-based extraction requires stable streams that are usually supported by a particular channel geometry (e.g. guide structure or small ‘pillars’) or surface chemistry, and flow parallel bounded by the liquid-liquid interface(Aota, Nonaka, Hibara, & Kitamori, 2006; Hibara et al., 2005; Hibara et al., 2002). Phases are disengaged downstream at a Y-junction, which is a qualitative difference between microfluidic and bulk extractions."

Jan 1, 2016

By M. Silva, G. Olivares

In a leach pile, the drainage layer or commonly known as the cover layer has been a matter of discussion due to the multiple phenomena or events that occur within it which impacts negatively the leaching process. All these events are directly related to the loss of draining capacity and irregular flow net due to an excessive compaction and entrapment of fines reducing the flow velocity which in turn cause more fines to get trapped. Over time the problem will continue to worsen rapidly and accelerating continuously like a geometric progression. When the cover layer gets to a certain level of deterioration, the only alternative to continue operating safely is to replace the entire cover material, a huge cost for any mining operation. TESRA has developed a solution to counteract the accelerated advance of the deterioration of the drainage layer. The solution consists of using large agricultural tractors coupled to a proprietary design of a heavy- duty subsoiler-ripper for deep tillage for loosening and breaking up the ground at various depth and with different legs spacing from 0.4 m or above. Also, if the ground still requires additional breaking, TESRA proposes the use of a rototiller that breaks any lumps to homogenize the ground to a certain particle size. With the subsoiler-ripper/rototiller combination equipment a layer of 0.5 m deep is properly treated to match closely the original conditions of the ground thus regaining the flow net as close as to the original seepage condition. Once the ripping is completed the subsoiler-ripper tool is replaced with another that is similar to a plow and thus continue with the installation of drainage pipes. The tool digs a Y-type profile trench allowing the pipe to sit precisely at the bottom of the trench, contributing additional lateral and lower support. This tool controls the installation depth of the drainage pipe at different inclination grades and also eliminating any irregularities that may block the flow of the leaching solution. Sometimes the obstructions block completely the flow of the solution. The main result of this methodology is the reduction of groundwater levels and at least 2% less humidity in the leaching gravel due to an increase in the draining capacity of cover. The methodology developed by TESRA applied during a couple of cycles of a dynamic leach pile has proven to be a real alternative to remedy and recuperate the cover close to its original conditions. The methodology requires only one large tractor and two accessories operated in different stages while replacing the more traditional and less efficient machinery such as the Bulldozer, Motor-grader, and backhoes.

Jan 1, 2019

By Lucas G. Thompson

My topic, "The Administration of Mineral Rights'.' is possibly an unusual one, as it deals with a subject upon which many of us have a more than passing interest, I thought ?it might prove consistent with the objects of this meeting, more especially as I propose to deal, not with those broad subjects of nation-wide importance which are often the subject'? of learned (and sometimes futile) academic discussion, but rather with problems in their practical light. To the scientist, the important question is What is it? to the technician, Can it be utilized? to the business-man, Will it pay? All three questions are important, and so quick has been the march of business on the heels of science? that the one question follows the other with astonishing rapidity and all three must be considered in the modern management of a mineral estate. A .good illustration of the force of this can be found in the recent advance of our knowledge of the element helium in which we have advanced from a solution of the first question to the last question in the short period of 55 years. It is to be borne in mind, however, that in the administration of mineral rights, the question "Will it pay?:' is of primary importance. What forms a mineral estate ? A former practice in western Canada in selling lands was to sell the hair with the hide. All transactions sold the lands in fee simple, which included all mines, minerals and rights and privileges whatsoever, excluding only the royal metals, gold and silver, which by imputation, though not by specific reference, in deeds. of title are reserved to the Crown. At that time the country was in the first ?stages of settlement and the value of our mineral resources was hardly appreciated and little understood.

Jan 1, 1923

By K. Kudo

Magnesium rods of 99.95% purity and approximately 6 mm in diameter were continuously cast at rates of between 15 and 25 mm/min by a heated mould process and their mechanical properties evaluated. It was found that rods cast at 15 and 20 mm/min consisted of a single crystal, while rods cast at a speed of 25 mm/min were multi-crystalline and showed a unidirectional structure. Although room temperature tensile ductility to fracture varied widely, it was found that with an appropriate crystal orientation, cast rods can exhibit elongation by as much as 215%.

Jan 1, 2006

By L. Hacini, N. Van L ê, P. Bacher, D. Thibault

Manufacturer welded components may suffer from high level of residual stresses which can cause premature cracking and decrease the life of the components if they reach values close to the yield strength of the material. In the present work, a robotized hammer peening technique is simulated by an impact machine and the residual stresses generated by the indentation are measured. To better understand phenomena behind residual stresses relaxation by hammer peening, the impact energy level was changed. 304L steel plates were hammer peened with 10 impacts. The contact between the hammer and sample surface was always at the same location. The strains on the surface close to the impact location were recorded during the test using strain gauges to follow residual stresses variations. At the end of the test residual stresses were measured indepth using hole drilling technique at 8mm from the impact center. The micro-hardness was monitored to evaluate the affected zone by the hammer peening. This approach gave a good estimation of the energy and number of blows to be used for efficient relaxation of the manufactured parts.

Jan 1, 2006

By Gilles Carrière

"The Suffield mine is situated five miles southwest of the city of Sherbrooke, in the Eastern Townships of Quebec. lt is the property of Suffield Metals Corporation Limited, a wholly owned subsidiary of Ascot Metals Corporation Limited.The old Suffield or Griffith mine had been worked intermittently from 1863 to 1906, without ever producing much ore. In 1951, diamond drilling done by Ascot Metals proved over one million tons of ore in three new bodies. The average grade of this ore was 0·018 ounces of gold per ton, 2-40 ounces of silver, l ·28 per cent copper, 0·59 per cent lead, and 6-45 per cent zinc. Since then the mine has been active, producing between 300 and 700 tons daily. More recent exploration has found continuations of the ore zones.General GeologyThe ore of the Suffield mine is found in porphyritic rhyolites of the Sherbrooke group (Silurian), at or close to its contact with sediments of the Beauceville group (Ordovician). The contact shows pronounced folds as well as irregularities due to erosion of the sediments prior to the outpour-ing of the lavas. On surface the general strike is north, and the dip is steeply east.The footwall sediments consist of interbedded black graphitic slates and. dark-coloured chloritic quartzite, overlain in many places by a thin bed of magnetite-hearing quartzite.The rhyolite host rock is a light grey rock, containing very abundant quartz and feldspar phenocrysts in a microcrystalline matrix of the same minerals. Some sericite is always present, especially in the vicinity of the ore zones, where the rock shows a pronounced schistosity.Several narrow basic dykes, with an easterly strike and vertical dip, cut all other formations. Most are lamprophyres, of either the monchiquite or camptonite type, but one has been identified as a diabase."

Jan 1, 1949

By Stephen Se

Geological assessment of active mine faces enables ore grade control, geological modelling and exploration planning. Monitoring of the mine advancement at every drill-blast-muck cycle allows for effective production management. However, geological assessments are performed infrequently due to the need to travel to active mine faces, and detailed surveys to map the mine progress are performed at the end of the month. Instant Mine Modeller (iMM) is a portable ruggedized stereo-vision system that creates photo-realistic three-dimensional models of underground mine faces on-site. The 3D models are generated automatically within minutes and can be viewed underground and annotated with geological information. The overall ore percentages of the face are calculated automatically for grade control. Annotated 3D models are located in the mine coordinate system and can be imported into mine management systems. iMM allows for daily monitoring of the mine progress and geology, and for re-visiting the mine virtually as it existed. iMM has been deployed in an underground hard rock mine for 18 months, and it effectively brings the underground work face into mine management offices enabling the right decisions at the right time. iMM has demonstrated benefits to various mine processes including grade control, geological mapping, 3D photo-realistic as-built and production volume.

Oct 1, 2009

By S. Nikolic, H. M. Henao

"There is renewed interest in the improvement of existing copper smelting processes and the development of new technologies. It has become clear that further accurate information on slag properties, in particular, on phase equilibria are required in order to optimize these processes. It is in this context that improved experimental research methodologies have been developed specifically to provide information on phase equilibria at the oxygen partial pressures encountered in copper smelting practice. The methodology involves synthetic slag equilibration at controlled gas atmospheres, quenching and measurement of compositions of phases with an electron probe X-ray microanalyser (EPMA) with wavelength dispersive detectors (WDD). Application of modem analytical tools and careful design of experiments greatly improve accuracy of determination of phase equilibria in complex, multi-phase slag systems. New experimental data on phase equilibria for the copper smelting and converting silicate slags at controlled oxygen partial pressures in the temperature range between 1200°C and 1350°C in the ""Fe0""-Ca0-SiO2 system and in the ""Cu20""-""Fe0""-Ca0-Si02 system in equilibrium with metallic copper are reported, and differences between various data sources are analyzed."

Jan 1, 2007

By A. Anderko, V. G. Papangelakis, G. Moldoveanu, G. Azimi, M. Carlos

"OLI Analyzer is a software package that uses the powerful Mixed Solvent Electrolyte (MSE) model to simulate the behavior of multicomponent electrolyte solutions from infinite dilution to the limit of fused salt, and from temperatures below the freezing point up to near critical temperature of the mixture. The software also allows the creation of thermodynamic parameters for new chemical systems unavailable yet in public-domain or commercial software databanks. This communication reviews the basics of the model and provides some examples of modeling hydrometallurgical applications with emphasis on high temperature applications, including calcium sulfate scale formation in autoclaves, high temperature pH inference and iron control. INTRODUCTIONModeling of electrolyte systems has been of particular interest to various industrial processes, such as separation processes (e.g., solution crystallization, extractive distillation, seawater desalination or bio-separations), environmental applications (e.g., gas treatment, wastewater treatment or chemical waste disposal) and hydrometallurgy (e.g., pH control and neutralization, iron control, scaling and fouling of equipment). Using a chemical model, time-effective predictions of various properties of electrolytes can be obtained, which is beneficial not only during process monitoring, but also during process optimization and process scale up. As a result, pilot scale studies can sometimes be eliminated where budgetary constraints exist. Development of such a powerful model requires the use of a speciation-based model, in which solution chemistry is explicitly addressed (as compared with some models that treat electrolytes either as undissociated or fully dissociated systems), despite being computationally challenging. In addition, as a feature of electrolyte systems, speciation equilibria inherently influence the phase equilibria due to complex formation, ion pairing, and acid-base reactions. Therefore, how the electrolyte solutions behave at various conditions may differ significantly due to the non-ideality, which must be carefully addressed to obtain a model that is applicable to a wide range of conditions such as concentration, temperature, pressure and solvent system."

Jan 1, 2012

By A. Ehsani

"Seas and oceans constitute about 70% of the earth’s surface. They contain an enormous stock of various mineral resources such as sedimentary (marine placers), massive sulfide ore deposits, manganese nodules and cobalt-rich ferromanganese crusts. Sea and ocean floor ore deposits could well contribute to the meeting of ever-rising demand for raw materials in the metal industry. In this regard, more research and development in science and technology appear to be required to ensure maximum benefit from the mineral resources of seas and oceans. Since the 1960s, a variety of mineral and metallurgical processes have been studied and developed to deal with marine ores and to extract metals such as gold, nickel, copper, cobalt, manganese, tin, platinum group metals (PGM), zirconium, thorium, etc.In marine environments, there are many parameters which can affect the selection of the mineral and metallurgical processes. These include the extent and grade of the deposit, mineralogical and chemical properties of the deposit, and physical properties of minerals present with particular reference to particle size distribution and mineral liberation size.In this paper, we briefly review the latest trends in processing and extraction of marine mineral resources. Mineral processing technology is mostly applied for recovery of precious metals i.e. gold and PGM, in particular, from marine placers. In general, pre-treatment (sizing, classification, dewatering), gravity concentration techniques (shaking tables, spirals, jigs, etc.,), flotation, magnetic, and electrostatic separation are the options for enrichment of marine placer ore deposits. In the case of massive sulfides, manganese nodules/cobalt-rich crusts, hydrometallurgical and pyrometallurgical methods (as proven technological methods) can be exploited for extraction of metals from concentrates after physical separation or directly from marine ores. The hydrometallurgical treatments involve acid (e.g., sulfurichydrochloric) and alkaline (e.g., ammonia) leaching with different reducing agents and pre-treatments such as roasting. Alternatively, pyrometallurgical treatments involve mostly smelting, chlorination and segregation processes."

Jan 1, 2016