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By C. Bernier

This paper deals with three major problems associated with mining operations during the winter. These are the maintenance of the cooling systems of diesel engines, the high incidence of hydraulic dump failures on packaging machines, and the build-up of frozen fines on wet-ore conveyor belts.

Jan 1, 1966

By N. Waters

"Nickel saprolite ores are normally mined as feed to Fe-Ni smelters or Ni matte smelting operations. The smelting processes typically require high Ni cut-off grades of approximately 1.5 to 2.2% Ni, depending on the operation. These very high cut-off grades result in a significant portion of the saprolite profile being regarded as “waste” and hence having little to no value. The Starved Acid Leach Technology (SALT) was developed to recover nickel and cobalt from nickel saprolites and Caron plant residues. Relatively small amounts of acid are applied to ground saprolites or Caron residues in order to selectively leach nickel and cobalt. The leaching is performed atmospherically under low free acid conditions. Nickel and cobalt may be recovered from the leachate as a mixed hydroxide. The mixed hydroxide may be added directly to a saprolite smelting operation or refined separately. InCoR Technologies is advancing the application of SALT at a number of sites. Bench scale testing has provided a relationship between acid addition and nickel extraction in leaching. Conceptual engineering studies have been completed by SNC Lavalin. The simplicity of the SALT technology provides the benefits of low capital and operating cost and an expected rapid ramp up to full production.INTRODUCTION The recent history of hydrometallurgical nickel laterite treatment plants has demonstrated mixed financial and operational performance. Table 1 summarizes the next generation plants built after the financial and/or technical failure of the Bulong, Cawse and Murrin-Murrin plants in Australia. The Coral Bay plants (Line 1 and 2) stand out (and now Taganito) as relatively low capital cost, simple (no acid plant, production of mixed sulfide product), and modest in scale (10, 12 and 36 kt Ni/a). However, the other plants in the list (Ravensthorpe, Ramu, Goro and Ambatovy) are all characterized by financial and technical challenges. All plants have a very high capital cost ($67,000 to $120,000 USD/annual t of Ni production). Ravensthorpe was sold by BHP Billiton after a poor startup. Ramu has had a steady ramp up but only produces mixed hydroxide for refining by others. Goro has had an extended construction period (since 2001), is high cost and has been very slow to ramp up to design production rates. Ambatovy has had a steady ramp up."

Jan 1, 2017

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 K. Parameswaran

This paper builds on presentations made at the Conference of Metallurgists (COM) 2015, COM 2017 and Extraction 2018 and associated papers published in the respective conference proceedings. Based on the classic Brundtland Commission definition of sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper describes how metal mining can be compatible with sustainable development and how sustainability considerations have been applied in the primary copper industry, using several examples of sustainable mining practices from ASARCO LLC operations. Finally, the paper discusses how these considerations might be used in the future by discussing the need for developing a sustainable development strategy and how this strategy can be aligned with the United Nations Sustainable Development Goals. INTRODUCTION The primary copper industry comprises: mining (also referred to as “extraction”); mineral processing (also referred to as “beneficiation, “milling” or “concentration,”) which includes leaching, solvent extraction (SX), crushing, grinding, froth and flotation operations; and metallurgical processing which includes smelting and converting; refining, which includes fire-refining or anode refining and electro-refining; and electrowinning (EW). There are two routes for producing refined copper: hydrometallurgical and pyrometallurgical. The hydrometallurgical route comprises mining (open-pit and underground), mineral processing (crushing and grinding — for heap leaching only; leaching and SX) and metallurgical processing (EW). The pyrometallurgical route involves mining, mineral processing (crushing, grinding and froth flotation) and metallurgical processing (smelting, fire refining and electro- refining). The primary copper industry is capital, water, resource and energy intensive with the potential for significant environmental impacts, if the environmental aspects are not properly managed. ASARCO LLC (Asarco) was organized in 1899 as the American Smelting And Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co-products. Grupo México, S.A.B. de C.V (Grupo México) acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, selenium and tellurium. Asarco operates three open-pit mines and mills, two leach, SX-EW plants, a copper smelter in Arizona and a copper electrolytic refinery in Texas.

Jan 1, 2019

By A. McLean, X. Men

"With high quality sulphide ores diminishing, nickel production from low-grade oxide ores becomes increasingly important and a major concern is the high sulphur level in the resultant ferro-alloy. So, desulphurization of the ferronickel becomes an important consideration. Red mud is a waste product of alumina industry and causes adverse effects on environment. In the present study, experiments were conducted to determine feasibility of using red mud as a major ingredient of refining fluxes for ferronickel desulphurization. In view of their influence on slag-metal separation, contact angle measurements between ferronickel alloy and molten slag made from red mud were also determined. INTRODUCTIONNickel is a very important metal that finds a variety of applications including consumer products, building, automotive and electronics. There are two kinds of ores containing nickel, namely oxide and sulphide ores. Anthony and Flett [1] reported that about 55% of the world’s nickel production originates from sulphide ores while the balance of new nickel is derived from oxide ores. However, oxide ores count for about 70% of the worldwide reserves. Apparently, oxide ores will play a significant role in the production of nickel in the future. Most of nickel produced using oxide ores is from pyrometallurgical processes namely ferronickel smelting or matte smelting. So, we can draw such a conclusion that using nickel oxide ores to produce ferronickel will become more and more important .Before used to make stainless steel or other materials, the ferronickel need pretreatment to remove impurities especially sulphur and phosphorus that will cause negative influence on the properties of steel product. Red mud is a by-product during alumina production. Usually, about 1 to 1.5 tons of red mud will be produced when we get 1 ton of alumina. About 90 million tones of red mud are produced every year in the world [2].Red mud is deemed as a toxic industrial waste which needs treatment before discharge because of alkalinity and chemical and mineralogical properties. Until now, the main means to deal with red mud are to store it in impoundments or dump it in the sea depending on local environment. Nowadays, how to recycle red mud has become a pretty hot topic around the world. The last 40 years have witnessed a lot of patent applications concerning the ways of red mud utilization. However, a little amount of red mud is consumed until now due to the limitations of recycling red mud."

Jan 1, 2012

By Chris Bennett, Glen Kosick

"Process modeling and equipment sizing procedures for SAG circuits has advanced significantly over the past two decades. However, no matter how exact the hardness tests, models and scale-up calculations, if the ore samples being used for design do not accurately represent the orebody then major design errors can be encountered. This paper will describe a hardness testing method for identiQing the power requirement profile of an orebody, to an extent that design errors due to poor sampling can be greatly reduced or avoided altogether. It will provide some insight into the magnitude of hardness variability that can be encountered in an orebody. Finally, the paper will preview how detailed hardness distribution data can be incorporated into mine block models, to optimize SAG circuit design for an orebody, both fi-om a capital investment and throughput point of view.INTRODUCTIONIt has long been known that many SAG/AG' circuits experience wide swings in throughput. These throughput variations are almost always of a magnitude not anticipated in the plant design; consequently, they are detrimental to the expected return on investment for the mining companies. It is clear that the throughput swings are mainly caused by changes in ore hardness. In 1993, in an attempt to address this problem, MinnovEX began investigating the possibility of using a small scale SAG test (2 kg charge) to predict SAG power requirements from drill core samples. The objectives of the small scale test were to enable mining companies to do many more SAG hardness tests than currently undertaken for a particular orebody. To make this possible, the SAG tests had to use a minimal amount of sample, be cost effective, and give acceptable accuracy in the prediction of SAG power. If this small scale SAG test proved accurate, then the high sampling frequency would yield results that approach the true hardness distribution of an orebody. This hardness distribution could then be used to derive the distribution and variability of specific energy required throughout the complete orebody. This specific energy (kWh/t) can be thought of as the power required to grind one tonne of ore per hour (kW/tph) to a specified size. Once the true distribution of power requirement throughout the whole orebody is understood, the grinding circuit design team can make an informed decision regarding the hardness value that is most appropriate for sizing the SAG equipment. Throughput losses due to hardness variation could be deliberately planned for or avoided altogether (a capital cost decision)."

Jan 1, 1999

By Mike Samuels, John Starkey

"This paper examines test results and grinding mill design for the recent Fortune Minerals’ NICO Project, located in the Northwest Territories. SAG milling and rod milling options are compared. Rod milling is clearly shown to be the best option because of the ore’s extreme resistance to breakage in a SAG mill environment.Surprisingly, the Bond Ball Mill Wi was 13 kWh/t for this ore. The Bond Rod Mill Wi was 20 kWh/t, whereas the SAG pinion energy to grind the ore to T80 1.7 mm was 30 kWh/t. The existence of ore with this ratio of SAG hardness to Bond BM Wi has not been previously observed. If not considered, this critical relationship may adversely impact the accuracy of mill design. This paper substantiates the significance of these findings to achieve successful grinding design on ore that is macro-competent during primary size reduction, but relatively normal during secondary grinding.INTRODUCTIONThe NICO Cobalt-Gold-Bismuth-Copper deposit is located 160 km northwest of the City of Yellowknife, Northwest Territories. It is the largest IOCG-type deposit (aka Olympic Dam-type) currently recognized in Canada with Mineral Reserves of 21.8 million tonnes contained within a larger 57 million tonne, lower-grade Mineral Resource. The project, owned 100% by Fortune Minerals Limited, has been assessed in a positive definitive feasibility study, subject to underground test mining and pilot plant testing, and is now in the permitting stage to develop a combined open pit and underground mine and process plant. An updated process flow sheet incorporates conventional crushing, grinding and bulk flotation, followed by filtration for shipment of a concentrate to a purpose-built refinery proposed to be built near Saskatoon, Saskatchewan. At the refinery, separate bismuth and cobalt concentrates will be produced following regrinding. The hydrometallurgical process methods include: pressure acid leach, precipitation, ion exchange, and electro-winning for recovery of cobalt as 99.8% cathode; solvent extraction and electro-winning of by-product copper cathode; ferric chloride leach and electro-winning for recovery of bismuth as 99.5% cathode; and cyanidation of the leach residues for recovery of gold as doré."

Jan 1, 2010

By Suzie Poulin, N. Geoffroy, G. P. Demopoulos

Most metallurgical industries generate toxic waste that must be treated prior to being released to the environment. However, in a lot of cases, the waste materials are poorly characterized or the analytical results are not well interpreted. These shortcomings often result in the development of inefficient industrial procedures, thus causing economic waste and difficulty meeting environmental regulations. Fortunately, a wide range of analytical techniques are available to guide researchers and engineers into making sound process development decisions. In this work, an industrial selenium and mercury removal process is used as an example to illustrate the application of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) on solid waste. Furthermore, samples of analytical results are presented and interpreted and the modifications to the industrial process that resulted are explained. Finally, a brief description of the advantages and limitations of the aforementioned analytical techniques is given with an emphasis on industrial solid waste material.

Jan 1, 2011

By Sengpasith Houngaloune

Arsenic, which is a toxic and carcinogenic element, causes serious environmental problems throughout the world. It is also known as a major contaminant in the non-ferrous mining and extractive metallurgical industries, thus its disposal is one of the most important environmental issues for the mining and metallurgical industries. In order to ensure a safe disposal environment for the final wastes, stabilization of arsenic has been studied extensively with various approaches. Solidification/stabilization (S/S) represents one of the most effective methods to reduce the availability of arsenic in soil and waste by transforming toxic or potentially hazardous phases into less hazardous ones. Cement based S/S processes could reduce the solubility of arsenic in solid waste, using inorganic binders such as cement, lime, and pozzolanic materials. A new tailings management technique, called cemented paste backfill (CPB), has become widely employed for improving mining techniques and for tailing storage purpose and this technique could also enhance arsenic stabilization, by fixing the contaminants in the binder matrix. Disposal of arsenic in the form of scorodite (FeAsO4?2H2O) has been widely accepted as currently the most suitable method for stabilization and the safest known storage material. The Bio-scorodite process has been reported to be more economic and environmentally friendly method than the chemical crystallization processes. Retention of arsenic by schwertmannite (Fe8O8(OH)6SO4), a metastable ferric oxyhydroxy sulfate mineral, has gained more attention in the recent years. Schwertmannite has a large specific surface area and high capacity to adsorb arsenic in solution. Several researchers have reported that the transformation of schwertmannite to goethite could be retarded by the presence of adsorbed arsenic; therefore schwertmannite might be viable alternative for long-term storage of arsenic. In this paper, various approaches used in arsenic stabilization are reviewed with emphasis on the development in the recent years.

Aug 1, 2013

By S. Aram

Product Lifecycle Management (PLM) solutions have been serving as the basis for collaborative product definition, manufacturing, and service management in many industries. They capture and provide access to product and process information and preserve integrity of information throughout the lifecycle of a product. Efficient growth in the role of Building Information Modeling (BIM) can benefit vastly from unifying solutions to acquire, manage and make use of information and processes from various project and enterprise level systems, selectively adapting functionality from PLM systems. However, there are important differences between PLM?s target industries and the Architecture, Engineering, and Construction (AEC) industry characteristics that require modification and tailoring of some aspects of current PLM technology. In this study we examine the fundamental PLM functionalities that create synergy with the BIM-enabled AEC industry. We propose a conceptual model for the information flow and integration between BIM and PLM systems. Finally, we explore the differences between the AEC industry and traditional scope of service for PLM solutions.

Aug 1, 2013

By Z. S. Abisheva

The Zhezkazgan copper sulfide ore deposit in Kazakhstan contains both rhenium and the rare osmium isotope "osmium-187" (187Os) in the high isotopic purity of 99.4 ± 0.2%. This isotope is believed to have originated as a result of the disintegration of one of the rhenium isotopes, according to the reaction: 187Re75 ?> 1870576 + B- + v~ (where B is a 13-particle, v~ is a 3-disintegration antineutrino). The distribution of osmium and rhenium in metallurgical byproducts produced during the recovery of copper from these ores has been studied and process flowsheets for the processing of rhenium and osmium-containing byproducts have been developed.

Jan 1, 2007

By C. A. Godden, T. N. Atkinson

Metallographic techniques developed from studies of corrosion films and electroplated coatings on aluminum alloys, are discussed. These methods, the result of work at the Naval Research Establishment, give extremely flat fields at the interface despite the large difference in hardness, in cases where electrolytic polishing could not be used. Techniques to overcome the similarity in refractive index of immersion oil, aluminum ox1d~, and mounting plastic are also considered, as are methods for improving visual and photographic contrast in areas of interest. A device for marking specimens is also de-scribed. ELE•CTROLYTIC polishing is inapplicable in the study of surface films on aluminum, whether corrosion films or electrodeposits. Mechanical procedures must there-fore be followed. Sample flatness and edge retention are of paramount importance. Special measures are required in the study of oxide films, because of the close proximity of the refractive indices of aluminum oxide, mounting plastic, and immersion oil.

Jan 1, 1962

By H. Thomasson

THE war, like all destructive agencies, has focused attention on salvage and conservation, and to such an extent that a decade of normal progress has been crowded into a few months. This is particularly true as regards the repair of cutting tools. As a consequence, there has arisen a wide demand for comparable data by those engaged in such work, and for basic information by others who wish to repair tools. These repairs may be grouped in three classes: (1) The repair of broken tools of relatively slender cross-section, such as broaches, reamers, drills, etc., of a type that could be returned to service if a means to join the broken surfaces were available, as fortunately it is in the low-temperature silver solder process; (2) the repair of tools that possess shanks, tangs, and other non-cutting portions that may be broken or damaged to the extent that only the addition of metal will permit their return to service; and (3) the repair of special rotating tools, such as end-mills and milling cutters, that may have portions broken from the cutting edges or have their edges so worn in service as to require building up.

Jan 1, 1943

By R. W. Lawrence, O. Lopez

Many gold deposits in the world have not been developed clue to the presence of copper and other base metals which can cause metallurgical and environmental challenges clue to the formation of base metal cyanide complexes. SART technology (sulphidization-acidification-recycle-thickening) can resolve these issues by recovering copper as a high grade sulphide concentrate, recycling the associated cyanide back to the gold leach, and eliminating the downstream environmental liabilities. Project economics can be improved substantially, leading to a positive re-evaluation of new and existing gold-copper projects. Some aspects of the design and operation of two recently commissioned SART plants will be discussed.

Jan 1, 2011

By E. P. Wiechrnann, C. M. Castro, G. A. Vidal, F. A. Muñoz

Different authors and publications indicate that Optibar Segmented Intercell Bars cause a remarkable distortion in the distribution of the current in a cell group. However, these results were based in inaccurate computer based models and do not represent the technology. During the last trimester of 2010, a 92 cells circuit from Barrick Zaldívar EW plant was implemented with Optibar Segmented Intercell Bars. The technology was incorporated progressively without disrupting the plant production. Depending on operational conditions, this led to a 2 to 4% current efficiency increase and 3 to 5% specific energy consumption reduction. By October 2011, 40,000 tons of copper will be produced with the technology.

Jan 1, 2011

By Lorne Sivertson, Peter Kitrredge

"World metallurgical coal imports totalled 110million tonnes in 1978. Of this amount, Japan imported 50 million tonnes, making it by far the largest and most important coking coal market . British Columbia and Alberta exported 12.0 million tonnes of coking coal in 1978, or 11% of the world total. Virtually all of these exports were directed to Japan, making up 22% of total imports.Some observers have suggested that because Japan is almost the exclusive buyer of British Columbia and Alberta metallurgical coal, the benefits of the coal trade may be primarily on the side of the powerful Japanese buyers. Buttressing this suspicion is the fact that Japanese trading companies have taken substantial equity positions in B.C. coal mines, thus presenting the possibility of non-arms-Iength transfer arrangements. There is then at least some evidence to support the hypothesis that Canada's western coal producers receive prices that are less than would prevail in a more competitive market; that is, that they are exploited.This paper produces evidence that Canada's coals are not underpriced in respect to U.S. and world markets. The conclusion is drawn that British Columbia and Alberta metallurgical coals receive prices that are equal to prices known to be competitively determined. This conclusion follows an in-depth analysis of prices, coal qualities and the economic characteristics of all major coals traded in the Japanese market. A by-product of the analysis is an equation capable of predicting the value of any metallurgical coal sold to Japanese buyers, or, for that matter, any buyer. Hopefully, this can be of some use to coal producers in developing their marketing strategies."

Jan 1, 1980

By Geoffrey C. Streeton

A continual objective of mine operations is to reduce ground control costs without compromising the overall safety or performance of the installed ground support. Any change in the ground support regime must not result in a less secure or safe workplace. The due diligence required to implement a change in rockbolting practice is extensive, particularly when the new bolting system has not been used at any other mining operation. Factors such as yield, shear strength and embedment strength must all be investigated to gain an understanding of how the rockbolt can be expected to perform. This paper also discusses the substantial cost reductions and efficiency gains which can be achieved through the introduction of the Jumbolt rockbolt.

May 1, 2001

By John Hoffert, Darren Colwell, Greg Tucker, Jeremy Kinch, Greg Rasmussen

"The Kemess Mine, a major producer of gold and copper, is located in north-central British Columbia. Kemess was brought into production in May 1998 by Royal Oak Mines. On February 11, 2000 Northgate Exploration Limited acquired Kemess Mine from receivership. Since acquisition in 2000 Kemess has seen many accomplishments, including the reduction of costs by 40%.One of the largest site capital costs was the construction of the tailings storage facility dam, which when finished will be one of the largest earth filled dam structures of its type. The existing construction design by AMEC called for a kilometer wide rock dam to be built from the 1350 M elevation to the 1504 M elevation at a 5.5:1 slope by hauling over 30 million tonnes of non-acid generating waste rock 7-kilometers from the open pit to the tailings dam, which was highly expensive.Kemess realized an opportunity for cost reduction was possible if the dam could be built from suitable quality tailings sand; however the sand did not meet the neutralizing potential ratio specifications. It was determined that cycloning combined with flotation to reduce pyrite concentration in the sand would produce a non-acid generating product for dam construction. The sand plant design challenges were to remove the sulphides from the tailings to obtain an NPR greater than 2:1 and provide a consistent sand product for the construction with a fines content of less than 15% passing 200 mesh. After a 2-year testing design and construction period, the sand plant was successfully started at the end 2002 resulting in higher than expected sand quality and production rates.This paper describes the plant design phase, commissioning, and operation of the tailings sand plant for construction of the tailing storage facility dam to enable us to meet all the engineering and regulatory requirements. The many challenges faced were successfully met using several innovative designs. The operational, economic, and environmental benefits are detailed."

Jan 1, 2004

By John Wilson

"The Rietveld numerical method was used to calculate the relative abundances of phases in both synthetic binary mixtures and synthetic and natural ores, using X-ray diffraction data. The results were compared with those of image analysis and a chemical method. The ranges of the relative errors were estimated. The Rietveld method is found to be acceptable for determining the abundances of major and minor phases and the amorphous component of partially crystalline samples. In complex mixtures, where there are several trace phases (~<2 wt%) present, the technique becomes less accurate. It is most useful as an alternative technique to image analysis when sample preparation is problematic or sample particle sizes are sub-micron. It is a manual method which requires user input during the fitting process, but is both simpler and faster than image analysis due to the reduced set up time and sample preparation required. It is now implemented at CANMET as a technique for quantitative analysis.INTRODUCTIONUntil recently, the Applied Mineralogy group at CANMET used only image analysis and chemical techniques to determine phase quantities. An effort to develop quantitative X-ray diffraction (XRD) has been on-going for several years. Initially, the reference intensity ratio (RIR) method with external standards was tried with some success (Szymanski and Petruk, 1989). The main difficulty with this technique was finding adequate standard material for each phase present in the sample. This shortcoming made the method ultimately impractical, given the wide variety of materials which come to the laboratory for analysis.The Rietveld refinement method of quantitative XRD (Hill et al 1993, Mumme et al 1996), in contrast, requires no standards and requires minimal sample preparation and therefore a more rapid turnaround compared to image analysis. The Rietveld method also has advantages over image analysis in that it can identify and quantify polymorphs, ultra fine materials and many types of hydroxide products. As well, it is useful for analyzing materials such as bauxite or talc, which do not polish well enough for making mounts of the quality required for image analysis. To quantify amorphous material and phases which are present in amounts below the detection limit of XRD, the addition of a standard material is still required. However, in such cases only one standard is needed, which is alumina."

Jan 1, 2003

By J. D. T. Steyl, C. A. Biley

"The chemistry of electrolyte systems containing iron remains generally poorly understood despite their prevalence in many natural and industrial processes, particularly in hydrometallurgy. These systems are typically challenging to study and model due to their affinity for complex formation and precipitation even at low pH. Recent developments in the hydrometallurgical processing of nickel laterites at Anglo American have called for a deeper understanding of the fundamental chemistry of the Fe2(SO4)3–FeSO4–H2SO4–H2O system. This paper details the development of an internally consistent, Pitzer ion-interaction model of this system, with explicit recognition of important contact ion pairs (CIPs). The primary application of this model is a thermodynamic framework for the interpretation of kinetic processes occurring during iron(III) reduction with SO2. Adopting a rigorous thermodynamic basis for the system chemistry facilitates the formulation of simple rate expressions that are capable of inherently capturing complex effects. While the iron(III) reduction case study remains the focus of this work, the developments have more universal applications and the thermodynamic speciation model can be extended into other systems containing acidic ferric sulfate.INTRODUCTIONIron is present in nearly all hydrometallurgical refining circuits typically as both a necessary and unwanted impurity and needs to be removed and disposed in a safe and efficient manner. This is generally performed by precipitation to form a range of solids such as hematite, goethite or jarosite. Numerous studies in the open literature have focussed on the removal of iron from refractory gold sulfide ore (Berezowsky & Weir, 1989; Berezowsky et al., 1991) and zinc pressure leaching (Buban, 1999; Ismael, 2003), and PGM matte sulfide circuits (Dutrizac & Monhemius, 1986). Moreover, since ferric iron is a strong oxidizing agent, it has been used extensively as a leaching agent for sulfide minerals (Dreisinger, 2006). Given the outlook of challenging economic conditions, declining ore grades and increasing levels of impurities, effective iron management is going to become increasingly critical to all hydrometallurgical processes.Against this background, and considering the widespread importance of acidic iron sulfate systems throughout natural and industrial processes, it is unexpected that the knowledge of the fundamental solution chemistry of these systems contains such significant gaps, particularly at the conditions typically found in hydrometallurgical applications. Existing literature describing the measurement and modelling of solution speciation in these systems have highlighted their significant chemical complexity (Magini & Caminiti, 1977; Magini, 1979; Lee & Tavlarides, 1985; Stipp, 1990; Papangelakis et al., 1994; Gil et al., 1995; Majzlan & Myneni, 2005; Kormanyos et al., 2008; Yue et al., 2014). Partially responsible for the lack of quantitative speciation measurements is the strong tendency of ferric to hydrolyse at even low pH (Flynn, 1984), complicating the laboratory study of such systems. Moreover, the large number of aqueous species that may co-exist simultaneously makes the study of individual species and the modelling of the numerous interactions between these species extremely difficult (Dry & Bryson, 1988; Stipp, 1990; Majzlan & Myeni, 2005; Kobylin et al., 2007)."

Jan 1, 2016