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By J. Manchisi

This study has investigated the use of blast furnace slag as functional adsorbent for metal ions in acid mine drainage treatment. This opportunity has not yet been developed into a practical process partly because of limited understanding of rates and mechanisms of adsorption process and inconsistency in interpretations of adsorption data. The overall objectives were to determine the efficiency and mechanisms of sorption process of metal ions in a multiadsorbate system. We employed standard materials characterisation techniques to analyse composition, structure and surface morphology of the slag. Batch adsorption experiments were then conducted to study the mechanisms, kinetics and efficiency of metal sorption as a function of pH, phase ratio, mixing time, mass and particle sizes of slag. Both XRF and adsorption data suggested the slag to possess acid neutralising capacity. This slag is non-crystalline based on XRD pattern, has adequate porosity and pore volume comparable to similar commercial adsorbents but it has inferior pore structure, pore size distribution and BET surface area to be effective under wide applications. Metal sorption increased with decrease in slag particle diameter, decrease in initial metal concentration and increase in the mass of slag. Although slags have demonstrated to efficiently treat low concentrations of single and multiadsorbate effluents using fine particle sizes, they have limited capacity to treat multiadsorbate systems for some metal ions. This is probably due to low affinity, competitive adsorption or limitation in material?s adsorptive properties. Sorption mechanisms probably involve precipitation and ion exchange on the basis of alkaline pH and exchangeable slag surface ions. Sorption preference is proposed as Fe2+>Cu2+>>Cd2+>Co2+>Mn2+. Despite these limitations, deeper understanding of sorption behaviour of metal ions by slags for application in dilute and large volumes of effluents is necessary where precipitation and other standard techniques are either inefficient or uneconomic. Thus, this study has established that sorption capacity of slag to remove metal ions from acidic effluents is selective, limited to certain metal ions and for other ions only at low concentrations. Further adsorption studies in multiple solutes under various experimental conditions or those that can propose an economic slag activation process are needed that improves or widens adsorption window.

Aug 1, 2013

By Robert B. Parsons

"""I would be a rich man if I had a dime for every man hour spent by the bureaucracy on changing tax legislation."" Anonymous.The mind of a cynic might very well conjure thoughts about ""change for the sake of change"", given the protracted saga of federal sales tax reform in Canada. The latest chapter unfolded this summer when the Commodity Tax Review Group released its important report. Whatever sales tax changes, if any, are finally adopted will have profound effects on many aspects of doing business. The capital-intensive mining industry will not escape these effects.IntroductionThe Federal Sales Tax Review Committee, established by the Minister of Finance earlier this year, has published a report that is sharply critical of the government proposals to shift the incidence of federal sales tax from the manufacturer level to the whole sale level (sales to retailers). The Report recommends a continuance of the present manufacturer's tax, for the present, but with significant changes that would increase the tax cost on certain imports, smooth the administrative machinery and make appeals and determinations more open and equitable. For the longer term, the Report recommends a shift of the tax base to the retail level.Reform of the federal sales tax system has been under consideration for several decades. Briefly the history is as follows: 1940 Report of Rowell-Sirois Commission-proposed the eventual elimination of federal sales tax1956 Report of Federal Sales Tax Committee-proposed a shift in tax from manufacturer to wholesaler level1966 Report of Carter Commission-proposed shift to a retail tax1975 Discussion Paper on Federal Sales and Excise Taxation-concluded that retail tax conceptually best but provincial agreement/administrative problems present a major hurdle-proposed wholesale tax as best practical approach1977 Report of Commodity Tax Review Group"

Jan 1, 1983

By Nicolas Gatelier, Sophie Laurent, Thierry You

Hard-rock caverns for hydrocarbon storage are a very particular type of underground facility controlled not only by local administrative and regulatory constraints that can be very specific, but also by the possible risks of geotechnical or geomechanical failure. Each such facility throughout the world is a prototype that needs to be adapted to very different site conditions. The straight forward application of design methodologies from relatively similar fields (mines, tunnels) can be very useful, but risks holding back the scientific and technical improvements needed by an engineering industry in full development. Here we look at various case histories and at problems that have been raised where recent attempts at standardization would appear to have been ill adapted, and where storage designers, through experience and judgment, may still provide innovative engineering solutions.

Jan 1, 2015

By S. Perkins, E. Young, L. Dufour, K. McVey, L. Rolandi

This paper presents a review of plant layout considerations incorporated into recent designs of SAG/Ball mill circuits for two medium sized concentrators. The plant layouts presented and the design concepts discussed, relate to smaller SAG circuits, but can equally apply to larger milling circuits. Included are design concepts and ideas introduced by the various project teams, and the focus is on the primary factors of any layout design which are safety, constructability, operability, and capital cost.

Jan 1, 2012

By W. Yang, R. Rajasingam, K. Mohanarangam

"Copper Electrowinning (EW) is a complex electrochemical process that involves the production of LME grade copper from copper rich electrolyte. The process involves the deposition of the copper ions onto the cathode from copper rich electrolyte with the production of oxygen bubbles at the anode. The process setups up a complex flow pattern within the cell as it is subjected to varying density gradients due to the deposition process along with oxygen bubble driven flow. It is a necessity to understand and quantify the flow behaviour within these cells in order to maintain the production of highest grade copper. In fact, the oxygen bubbles originating from the process is responsible for the generation of acid mist which is a designated as a carcinogen a major health hazard around EW tank houses. Hydrodynamic assessment of the process has so far been restricted to simple mass balances and some limited numerical modelling. All the models are based on assumed boundary conditions which has not so far been verified by any real-time physical measurement. This apparent gap has led to models which could not be directly used to track process changes or troubleshoot problems in EW tank houses. In order to address this gap, CSIRO has established a full size (width and height) transparent cell capable of simulating plant operating conditions (across the range currently used). With the use of sophisticated diagnostic analytical tools and measurement techniques it was possible to study all the operating variables (current density, flow rate, temperature, etc.) independently and their effect of bubble size, bubble velocity, gas hold-up as well as acid mist generation and its size. In order to address safety concerns in tank houses around acid mist early results outlining the factors contributing to its generation as well as the effect of various barriers to mitigate acid mist is outlined below.INTRODUCTIONA significant part of today’s copper production is through hydrometallurgical route which predominantly involves leaching, Solvent eXtraction (SX) followed by ElectroWinning (EW). Producing copper using this approach have shown to be environmentally friendly (Dresher, 2001) compared to the traditional smelting process. EW is the final step in the production of LME grade copper using the hydrometallurgy route. The electro-chemical process involves the use of a lead anode (Pb-Sn-Ca) and a stainless steel cathode to produce copper sheets using the copper rich electrolyte from the SX process and with the applications of direct current to the electrodes. This electro-chemical reaction results in the deposition of copper ions on the cathode with oxygen released from the anode as a by-product. Hydrodynamically, the oxygen bubbles create a bubble driven flow within the EW tanks with the surrounding electrolyte. A direct result of this could be seen from the quality of the copper deposited on the cathode. Most of the copper plates produced from the traditional tank houses have a rough texture at its bottom one-third while the top two-thirds have a smooth finish with a finer grain structure."

Jan 1, 2016

By Dale L. McKinnon, Jean-Pierre Farant

"Dust collectors are used to reduce airborne dust levels generated during crushing at a mining operation and their adequate maintenance is required to ensure effective control of health and safety hazards associated with dusty conditions. Although the pitot traverse technique is commonly employed to balance these dust collectors, the use of an alternative-the equilibrium concentration tracer gas method-is proposed in this paper. This method, which uses sulphur hexafluoride as a tracer gas, can be used to balance airflows in dust collectors and to determine hood collection efficiency accurately and effectively. This technique also reduces some of the errors inherent to pitot tube measurements. IntroductionIndustrial dust collectors are used to reduce dust genera ted by processes like cru shin g, and these must be periodically checked and balanced to ensure continuing effective control of health and safety hazards associated with dusty conditions.To date, the pitot tub e traverse technique has been commonly used to balance air flows in dust collectors. However, this technique is both time -consuming and cumbersome. The equilibrium concentration tracer gas method, described in this paper, is proposed as a viable alternative as it is faster, more reliable, and amenable to automation. The use of tracer gases for such task s is not new. This approach has been used in a variety of mining situations to determine volumetric flow rates in underground openings, leak age through mine stoppings, the effectiveness of face ventilation, pollution migration patterns, mine air recirculation rates, and rock porosity."

Jan 1, 1986

By S. Avalos, J. M. Ortiz, W. Kracht

Semi-autogenous grinding mills are intensive energy consumers. Current models base their energy consumption inference on operational variables and feeding ore characterization. While they provide adequate design guidelines, they are not suitable for real-time energy forecasting dealing with gaps in operational dataset and up/downstream process bottlenecks. This work explores the capability of Gated Recurrent Units to learn the semi-autogenous grinding mill consumption behaviour. Gated Recurrent Units are trained to forecast different time-support consumptions under a time-series operational dataset. The results show high performance on small supports (30 minutes) to capture local variability and long-trends while larger time supports (8 hours) can only capture time-trends but not local variability. The proposed technique seems promising for further research and implementation on real mine cases since the input variables are low-cost and easy to obtain. INTRODUCTION Current changes in the Chilean energy matrix (Román-Collado, Ordoñez, & Mundaca, 2018), from fossil fuels to renewable energies, have impacted different industries and particularly the mining sector. Solar energy incorporation into greenfield/brownfield projects will help reducing costs and will lead to rethink foundational paradigms (production and processing strategies) (Pamparana et al., 2017). Also, integration of new space-time predicting tools together with automated real-time updating models are some of the main challenges in the geometallurgical framework (Ortiz et al., 2015; van den Boogaart & Tolosana-Delgado, 2018). Those contexts encourage and demand the development of tools capable of predicting the energy consumed by mining systems, being comminution the greatest energy consumer with an average close to 50% of the entire mine consumption (Cochilco, 2013). In comminution, the semi-autogenous grinding mill (SAG) represents the largest energy consumer (~10 nominal each SAG). Theoretical and empirical energy consumption models (Jnr & Morrell, 1995; Morrell, 2004; Silva & Casali, 2015) base their inferences mainly on feed/product size distributions, SAG sizing, bearing pressure, feed hardness, water addition and grinding charge level, and commonly assume steady-state and work isolated from up and downstream processes. While those techniques provide adequate design guidelines, they are not suitable to predict hourly, daily or even weekly energy consumptions on interconnected comminution circuits where upstream/downstream bottlenecks lead SAGs to operate below designed regimes. Forecasting energy consumption is required by short-term energy management, medium and long-term planning energy consumption, designing the nominal capacity of renewable energy sources, among other. Also, when models are input-sensitive and some of those input measurements are expensive and/or time consuming, model robustness suffers when real-time predictions are required.

Jan 1, 2019

By Dwayne D. Tannant

Digital photogrammetry allows rapid, remote measurement of millions of points, thus providing an unprecedented amount of spatial information. Research is being conducted to explore practical applications of digital photogrammetry for monitoring, surveying and mapping in surface mines. The performance, accuracy and operational ease of digital photogrammetry are discussed and practical aspects of conducting digital photogrammetry surveys are reviewed. Case histories from coal, diamond and limestone mines are presented.

May 1, 2006

By M. Soleimanifar

With more and more industrial construction projects implementing RFID and other sensor-based technologies on fabrication and project sites, new innovative processes are needed to help automatically read and re-position RFID tags while reducing the cost to deploy RFID infrastructure over large areas. RFID tags are being used on construction sites to help identify the location of materials, equipment and personnel to aid in finding project critical materials and equipment required to construct the industrial facility on time and on budget. This research provides a cost-effective process for reading tens of thousands of RFID tags over large project sites from outdoor laydown yards, to warehouses to the workface where the materials and tagged equipment are installed. Based on the collected RFID and sensor data, localization mechanisms determine the most recent coordinates of the tagged components. The paper will cover analysis of RFID collected data and key lessons learned from a commercial deployment of the SiteSense® system with one Alberta-based industrial contractor, JV Driver Fabricators, at an 80-Acre module, pipe spool and structural steel fabrication site.

Aug 1, 2013

By B. W. Brooks

"After an extensive period of University research and field trials, large scale reclamation of the Waite Amulet tailings discharge areas commenced in the spring of 1978. The Noranda program consists principally of sampling the complete dam to determine the vegetation potential of the various areas, addition of the required amelioration materials, and the use of good agricultural practices. This paper describes the development work that led to the establishment of the Noranda-Guelph Contract and the subsequent findings concerning the revegetation of tailings dams. Current revegetation procedures are presented. INTRODUCTIONThe Amulet Mine Ltd. was staked in 1924 and by 1930 had constructed a small 300 ton per day flotation plant. During the late twenties and early thirties, Noranda Mines Ltd. increased its equity in the company to gain a sixty percent share of this small mine. In 1933 the mine was amalgamated with another small producer, the Waite Ackerman Montgomery Mine Ltd., which was more than eighty per cent controlled by Noranda to form the Waite Amulet Mines Ltd.An interesting historical side point to the story of the Waite Ackerman Montgomery property is that a concentrator was never constructed. In fact, the first ore to go through the Horne mill of Noranda Mines Ltd., built in 1928, was not from the famous upper H and L ore bodies but custom shipments from the Waite."

Jan 1, 1981

By A. E. M. Warner, A. Vahed, P. J. Mackey

In the decade 2002 to 2012 some 6.7 million tonnes of new copper concentrate production capacity was brought on line, corresponding to 2 million tonnes of contained copper. This increase in concentrate supply necessitated the commissioning of a number of new copper smelters as well as the modernization and/or expansion of existing plants to meet the demand. This paper gives an overview of the copper extractive industry, reviews recent copper production trends and changes in the copper industry, including an examination of pyrometallurgical and hydrometallurgical technology developments. WorleyParsons has supported a number of the projects involved in these developments and this role is briefly discussed. The paper introduces a number of ideas related to possible future directions of the copper industry.

Jan 1, 2014

By X. Cao, M. Xiao, M. Jahazi

Magnesium alloys have low hardness, wear, erosion and corrosion resistance. The repair of service-damaged aerospace components made of magnesium alloys is an attractive solution in terms of time and cost saving. The feasibility of applying laser beam technology to repair ZE41A-T5 magnesium alloy sand castings in the machined surface conditions was studied using a continuous wave 4 kW Nd:YAG laser system. The influence of process parameters such as laser power, cladding speed, wire feed rate and defocusing distance on the shape, size and area of single cladding beads is discussed using a process optimization software. Sound single clad beads with good geometric characteristics were obtained using strictly controlled laser process parameters. The overall results indicate that laser surface cladding using filler wire has the potential for repairing aerospace components made of cast magnesium alloys.

Jan 1, 2006

By Michael S. Moats, Shijie Wang, Timothy Robinson

In 1987, John Schloen published a survey and analysis of copper electrorefining tank room data. Following this paper, a series of copper electrorefining surveys have been conducted and presented at each of the Copper-Cobre meetings over the past 20+ years (1991, 1995, 1999, 2003, 2007, 2010 and 2013). For each of these surveys, William Davenport has been key driving force in the collection and analysis of data. To honour Professor Davenport’s contribution to copper processing, a review of the data was conducted. Historic trends and possible future technologies are discussed.

Jan 1, 2014

By M. R. Julien

"The geomechanical behavior of rocksalt shows very distinctive features. The response of this most ductile of all low porosity rocks is dominated by inelastic processes that are strongly time- and historydependent. These characteristics must be taken into account when analyzing underground openings. Different constitutive models have been proposed and used for this purpose, and this paper presents the general formulation and applications of one of these. The SUVIC model relies on a unified approach with internal state variables producing mixed hardening to represent the inelastic behavior, which lead to specific solutions for plasticity and creep. The model equations have been implemented into a finite element code to perform numerical analyses. Simulations results are presented to show that this model captures essential aspects of rocksalt behavior under simple and complex laboratory testing conditions. Simulations are also conducted to analyze the response of underground openings. INTRODUCTIONPredicting the response of man-made excavations in rocksalt can be quite a challenge as it requires a reliable constitutive model to represent the material behavior. This softest of all low porosity rocks shows a highly non-linear inelastic behavior, very sensitive to history and rate effects (e.g. Senseny et al., 1993; Cristescu & Hunsche, 1997; Julien, 1999; Wittdke, 2014). The many deformation (micro) mechanisms acting locally in rocksalt make the construction of appropriate constitutive equations quite complex. Nonetheless, there have been significant progresses made over the last two decades or so; many of these developments have been included in a series of specialized Conferences Proceedings (Ghoreychi et al., 1996; Aubertin & Hardy, 1998; Cristescu et al., 2002; Wallner et al., 2007; Bérest et al., 2012)."

Jan 1, 2015

By I. A. Cameron, F. Ham, R. Sriram

"Planned increases in electric furnace productivity and higher matte temperatures needed for the Sudbury Smelter's S02 Abatement Plan, require an improved matte tap hole. Since startup in 1978, the matte tap holes have been incrementally improved by the addition of copper cooling blocks around the refractory tap blocks. These improvements provided a tap block life of about 100 taps per campaign.In July 1993, a prototype matte taphole was installed in Number 2 Electric Furnace to develop the technology to increase tap hole service life. The design was based on a heat transfer model of the tapping process to determine candidate refractory materials and cooler arrangements. The prototype tap hole features increased copper cooling, high conductivity refractories and extensive instrumentation. Eight trial campaigns are reviewed outlining the performance of silicon carbide and graphite refractories and typical heat loads during tapping.IntroductionFalconbridge Limited operates two 36 MYA, 6 electrode submerged arc electric furnaces in Falconbridge, Ontario. The furnaces, commissioned in 1978, smelt a partially roasted nickel-copper calcine, to produce matte for converting and slag for discard. Additional details of the smelter are available in the literature(1-4).Each furnace was equipped with two matte tap holes located in the furnace end wall. Early in the campaign, matte tap holes were identified as a weak area in the furnace which could be improved. From 1981 to 1987, incremental improvements were made to the design by the addition of water cooled copper blocks. In 1993, a prototype matte tap hole was designed and installed in Number 2 electric furnace to develop the technology to increase tap hole service life. Improved service life is required to meet planned increases in electric fWl1ace productivity and the higher matte temperature needed for the smelter's S02 Abatement Plan.This paper reviews matte tap hole development since 1978; outlines the prototype matte tap hole design, refractory selection and installation; and details the performance of the prototype tap hole during the first eight campaigns."

Jan 1, 1995

By T. Negeri, M. Boisclair, A. Bouajila

CanmetMINING has been working on process development for separation and concentration of rare earth bearing minerals from various ores. Among others, the flowsheet development for the Montviel Rare Earths/Nb deposit, located at the north end of the Abitibi region in Quebec and owned by GeoMegA Resources Inc. (GeoMegA) is now at an advanced stage. The concentrate produced by a flotation-only process at the early stage of the project accounted for higher than 90% TREO and Nb recovery in 40% mass. This concentrate was submitted to SGS Lakefield for hydrometallurgical processing. Lixiviation of the concentrate using hydrochloric acid yielded approximately 99 % REE. An overall (from ore in ground to final precipitate) REE recovery of 80% was obtained through a series of selective precipitation steps. Recently significant additional developments have been made. CanmetMINING is steadily improving the quality of concentrate produced through a simplified, more efficient flowsheet which consists of flotation, magnetic separation, and a thermal treatment procedure. The paper discusses aspects of the process that allowed obtaining 82% recovery of TREO and Nb in 16% of mass, the best result to-date.

Jan 1, 2014

By C. R. Edwards, D. R. G. Watt

"Equity Silver Mines Ltd. a member of the Placer Development group of companies operates Canada's largest silver mine near Houston in north-central British Columbia. Initially, the silver-gold-copper flotation concentrate contained excessive levels of antimony and arsenic, so a leach process was installed to remove undesirable metals and provide improved smelter terms for the leached concentrate. The leach plant which has been fully described elsewhere (1, 2, 3), was forced by deteriorating process economics to shut down in April 1984. Equipment was mothballed and alternate uses sought.The Endako Mines Division of Placer Development Limited, located some 150 kilometres east of the Equity mine site, shut down its molybdenite mining and milling facilities in the spring of 1982. Endako has continued to produce molybdic oxide (molybdenum trioxide or MTO) via intermittent roaster runs, and also a high purity, lubricant grade molybdenum disulfide in the Ultrapure Plant. With the steel industry in the doldrums, molybdenum chemicals present an alternate and growing potential for molybdenum sales. In 1982 Placer Development began testing this market. Molybdenum chemicals were produced in the United States on a toll basis using Endako MTO as process feed. The transfer of this production to Canada was being considered when Equity's leach plant shut down, and it was noted that most of the equipment and skills necessary could be provided by the leach plant. See Figure 1.A careful investigation of process requirements was completed by engineering and production staff at Equity and Endako. A provisional capital and operating cost estimate was made, and it was decided to perform a test run during July 1984. There were strong reasons to proceed with this project. A positive cash flow was expected for both Endako and Equity. Endako would have product to continue to expand in the molybdenum chemicals market with the added selling point that now the complete production process would be under direct control of Placer Development companies. Equity would further benefit since a portion of the leach plant would continue in operation thus maintaining and exercising our hydrometallurgical engineering and operating skills. Finally, Equity would have a base from which to search out other processes adaptable to the idled leach plant equipment."

Jan 1, 1986

By Debasis Deb, Ankur Narang, G. P. Raja Sekhar, Kamal C. Das

"The stability of underground structures made (especially) in jointed rock mass is of the utmost important to designers, engineers and operators. Rock bolting is generally being practised to reinforce excavation walls and roofs by minimizing the movement of rock joints. This study proposes a new analytical model for the prediction of displacements, axial load and shear stress of a fully grouted rock bolt intersected by single or multiple rock joint(s). The governing equations for rock bolt are derived based on the assumption that shear force generated by slippage along the bolt-grout interface has a linear relationship with respect to the relative displacement at the interface. The proposed model is novel compared to the existing literature in the sense that it accounts for rock kinematics as an enriched sum of a continuous part (elastic) and a discontunous (jump) part due to the presence of joint planes. The complete solution of the bolt displacement, axial load and shear stress is derived as a function of the rock displacements, and, it comprises of Heaviside and/or Dirac delta functions in the solution space due to the jump at the intersection point(s) of bolt(s) and joint(s).Our novel solution is able to predict the elastic behavior of a grouted bolt, subjected to opening of the joint planes in pull-out test and also in excavated tunnel. These two cases also serve as benchmarks for grouted rock bolts with multiple joints and can be used for validation of numerical and experimental models. Further, the solution is applied to analyze the behaviour of grouted rock bolt as well as cable bolt installed in circular tunnel, with variations in rock joint(s) opening displacement, shear stiffness in the boltgrout interface and locations of the joint planes. Results indicate that for a specified grout stiffness, the maximum axial load developed in the bolt for discontinuous distribution of rock mass displacement is significantly higher than that of the continuous distribution of rock displacement. This paper provides an analytical interpretation of bolt beaviour considering multiple joint planes with variable joint opening displacements. The results obtained via the analytical method are in line with the corresponding investigation done by other authors. Thus, our analytical treatment can be used to understand bolt behaviour in realistic situations."

Jan 1, 2015

By Greg Collins

BUCKO EXPLORATION HISTORY ??1964-Discovery ??1970?s -114 holes totaling 34,000 metres drilled -vertical shaft excavated to a depth of 300 metres (1000 Level) plus 800 metres of underground development -Exploration program cancelled due to Falconbridge economic issues ??1990?S-19 holes drilled totaling 9,600 metres ??2000 -13 hole 4,600 metre exploration program by Nuinsco Res.

May 1, 2006

By C. A. Biley

"A dedicated iron removal stage was installed at Anglo American Platinum’s Rustenburg Base Metals Refiners (RBMR) during an expansion project which began execution in 2010. The Pressure Iron Removal (PIR) process aims to precipitate iron from a nickel leach solution under medium temperature (145 °C) oxidative conditions using caustic for neutralisation. Since commissioning, the process has been robust in removing iron from the refinery but has shown significant variability in the residues produced. These residues, which are typically comprised of ferrihydrite, hematite or natrojarosite, have varying iron contents and different physical properties which have implications for their filtration and ultimate removal from the refinery. Since over 95% of nickel plated at RBMR passes through the PIR section, volumetric constraints caused by poor filtration performance directly influence nickel production and stabilisation of this process remains central to the continued ramp-up of the refinery to full nameplate capacity. This paper details the development of the PIR process and the journey from concept to implementation. Recent laboratory and plant scale tests have highlighted the importance of the initial phase formed in the autoclave for the ultimate residue requiring filtration and how the feed acid concentration is a critical control parameter. On this basis, a new caustic dosing philosophy was implemented which improved pH control in the autoclave. Further optimisation of the PIR process is on-going.INTRODUCTIONIn 2010, an expansion of Rustenburg Base Metal Refiners (RBMR) to increase nickel production from 21 to 33 ktpa began execution. The management of iron was pivotal in the ultimate configuration in the new circuit and one of the primary differences from the original circuit was the addition of a dedicated iron removal stage: Pressure Iron Removal (PIR). A significant drive for this new unit operation was to facilitate the separation of iron from other leach residues. Not only did this result in a significant decrease in the amount of leach residue but, without the constraints associated with iron precipitation during leaching, has permitted more aggressive leaching conditions and, correspondingly, greater throughput and efficiencies.However, as with many commercial implementations of even mature technologies, the journey from development to implementation has presented challenges for the continued ramp-up of the refinery to full nameplate capacity. Specifically, since all nickel bearing leach solution must pass through the PIR section prior to the nickel purification and recovery circuit, throughput difficulties in the PIR section can directly impact supply of feed to the nickel tank house. Since commissioning, the PIR autoclave has effectively removed iron from the refinery, but has shown significant variation in the solids phases produced in the autoclave. This variation presents difficulties for the filtration of the discharge slurry and represents a key throughput limitation which periodically impacts production. Additionally, the increasing production rates associated with the ramp-up of the refinery have resulted in a significant increase in the required volumetric throughput through the PIR process. This has placed even greater emphasis on improving the stability of the solid phase produced in the autoclave, ultimately targeting an easily filterable residue with high iron content."

Jan 1, 2016